i2c-core-base.c source code [Linux/drivers/i2c/i2c-core-base.c]

1	// SPDX-License-Identifier: GPL-2.0-or-later
2	/*
3	* Linux I2C core
4	*
5	* Copyright (C) 1995-99 Simon G. Vogl
6	* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>
7	* Mux support by Rodolfo Giometti <giometti@enneenne.com> and
8	* Michael Lawnick <michael.lawnick.ext@nsn.com>
9	*
10	* Copyright (C) 2013-2017 Wolfram Sang <wsa@kernel.org>
11	*/
12
13	#define pr_fmt(fmt) "i2c-core: " fmt
14
15	#include <dt-bindings/i2c/i2c.h>
16	#include <linux/acpi.h>
17	#include <linux/clk/clk-conf.h>
18	#include <linux/completion.h>
19	#include <linux/debugfs.h>
20	#include <linux/delay.h>
21	#include <linux/err.h>
22	#include <linux/errno.h>
23	#include <linux/gpio/consumer.h>
24	#include <linux/i2c.h>
25	#include <linux/i2c-smbus.h>
26	#include <linux/idr.h>
27	#include <linux/init.h>
28	#include <linux/interrupt.h>
29	#include <linux/irq.h>
30	#include <linux/jump_label.h>
31	#include <linux/kernel.h>
32	#include <linux/module.h>
33	#include <linux/mutex.h>
34	#include <linux/of_device.h>
35	#include <linux/of.h>
36	#include <linux/pinctrl/consumer.h>
37	#include <linux/pinctrl/devinfo.h>
38	#include <linux/pm_domain.h>
39	#include <linux/pm_runtime.h>
40	#include <linux/pm_wakeirq.h>
41	#include <linux/property.h>
42	#include <linux/rwsem.h>
43	#include <linux/slab.h>
44	#include <linux/string_choices.h>
45
46	#include "i2c-core.h"
47
48	#define CREATE_TRACE_POINTS
49	#include <trace/events/i2c.h>
50
51	#define I2C_ADDR_OFFSET_TEN_BIT 0xa000
52	#define I2C_ADDR_OFFSET_SLAVE 0x1000
53
54	#define I2C_ADDR_7BITS_MAX 0x77
55	#define I2C_ADDR_7BITS_COUNT (I2C_ADDR_7BITS_MAX + 1)
56
57	#define I2C_ADDR_DEVICE_ID 0x7c
58
59	/*
60	* core_lock protects i2c_adapter_idr, and guarantees that device detection,
61	* deletion of detected devices are serialized
62	*/
63	static DEFINE_MUTEX(core_lock);
64	static DEFINE_IDR(i2c_adapter_idr);
65
66	static int i2c_detect(struct i2c_adapter adapter, struct* i2c_driver *driver);
67
68	static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key);
69	static bool is_registered;
70
71	static struct dentry *i2c_debugfs_root;
72
73	int i2c_transfer_trace_reg(void)
74	{
75	static_branch_inc(&i2c_trace_msg_key);
76	return `0`;
77	}
78
79	void i2c_transfer_trace_unreg(void)
80	{
81	static_branch_dec(&i2c_trace_msg_key);
82	}
83
84	const char *i2c_freq_mode_string(u32 bus_freq_hz)
85	{
86	switch (bus_freq_hz) {
87	case I2C_MAX_STANDARD_MODE_FREQ:
88	return "Standard Mode (100 kHz)";
89	case I2C_MAX_FAST_MODE_FREQ:
90	return "Fast Mode (400 kHz)";
91	case I2C_MAX_FAST_MODE_PLUS_FREQ:
92	return "Fast Mode Plus (1.0 MHz)";
93	case I2C_MAX_TURBO_MODE_FREQ:
94	return "Turbo Mode (1.4 MHz)";
95	case I2C_MAX_HIGH_SPEED_MODE_FREQ:
96	return "High Speed Mode (3.4 MHz)";
97	case I2C_MAX_ULTRA_FAST_MODE_FREQ:
98	return "Ultra Fast Mode (5.0 MHz)";
99	default:
100	return "Unknown Mode";
101	}
102	}
103	EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
104
105	const struct i2c_device_id i2c_match_id(const* struct i2c_device_id *id,
106	const struct i2c_client *client)
107	{
108	if (!(id && client))
109	return NULL;
110
111	while (id->name[`0`]) {
112	if (strcmp(client->name, id->name) == `0`)
113	return id;
114	id++;
115	}
116	return NULL;
117	}
118	EXPORT_SYMBOL_GPL(i2c_match_id);
119
120	const void i2c_get_match_data(const* struct i2c_client *client)
121	{
122	struct i2c_driver *driver = to_i2c_driver(client->dev.driver);
123	const struct i2c_device_id *match;
124	const void *data;
125
126	data = device_get_match_data(dev: &client->dev);
127	if (!data) {
128	match = i2c_match_id(driver->id_table, client);
129	if (!match)
130	return NULL;
131
132	data = (const void *)match->driver_data;
133	}
134
135	return data;
136	}
137	EXPORT_SYMBOL(i2c_get_match_data);
138
139	static int i2c_device_match(struct device dev, const* struct device_driver *drv)
140	{
141	struct i2c_client *client = i2c_verify_client(dev);
142	const struct i2c_driver *driver;
143
144
145	/ Attempt an OF style match /
146	if (i2c_of_match_device(matches: drv->of_match_table, client))
147	return `1`;
148
149	/ Then ACPI style match /
150	if (acpi_driver_match_device(dev, drv))
151	return `1`;
152
153	driver = to_i2c_driver(drv);
154
155	/ Finally an I2C match /
156	if (i2c_match_id(driver->id_table, client))
157	return `1`;
158
159	return `0`;
160	}
161
162	static int i2c_device_uevent(const struct device dev, struct* kobj_uevent_env *env)
163	{
164	const struct i2c_client *client = to_i2c_client(dev);
165	int rc;
166
167	rc = of_device_uevent_modalias(dev, env);
168	if (rc != -ENODEV)
169	return rc;
170
171	rc = acpi_device_uevent_modalias(dev, env);
172	if (rc != -ENODEV)
173	return rc;
174
175	return add_uevent_var(env, format: "MODALIAS=%s%s", I2C_MODULE_PREFIX, client->name);
176	}
177
178	/ i2c bus recovery routines /
179	static int get_scl_gpio_value(struct i2c_adapter *adap)
180	{
181	return gpiod_get_value_cansleep(desc: adap->bus_recovery_info->scl_gpiod);
182	}
183
184	static void set_scl_gpio_value(struct i2c_adapter adap, int* val)
185	{
186	gpiod_set_value_cansleep(desc: adap->bus_recovery_info->scl_gpiod, value: val);
187	}
188
189	static int get_sda_gpio_value(struct i2c_adapter *adap)
190	{
191	return gpiod_get_value_cansleep(desc: adap->bus_recovery_info->sda_gpiod);
192	}
193
194	static void set_sda_gpio_value(struct i2c_adapter adap, int* val)
195	{
196	gpiod_set_value_cansleep(desc: adap->bus_recovery_info->sda_gpiod, value: val);
197	}
198
199	static int i2c_generic_bus_free(struct i2c_adapter *adap)
200	{
201	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
202	int ret = -EOPNOTSUPP;
203
204	if (bri->get_bus_free)
205	ret = bri->get_bus_free(adap);
206	else if (bri->get_sda)
207	ret = bri->get_sda(adap);
208
209	if (ret < `0`)
210	return ret;
211
212	return ret ? `0` : -EBUSY;
213	}
214
215	/*
216	* We are generating clock pulses. ndelay() determines durating of clk pulses.
217	* We will generate clock with rate 100 KHz and so duration of both clock levels
218	* is: delay in ns = (10^6 / 100) / 2
219	*/
220	#define RECOVERY_NDELAY 5000
221	#define RECOVERY_CLK_CNT 9
222
223	int i2c_generic_scl_recovery(struct i2c_adapter *adap)
224	{
225	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
226	int i = `0`, scl = `1`, ret = `0`;
227
228	if (bri->prepare_recovery)
229	bri->prepare_recovery(adap);
230	if (bri->pinctrl)
231	pinctrl_select_state(p: bri->pinctrl, s: bri->pins_gpio);
232
233	/*
234	* If we can set SDA, we will always create a STOP to ensure additional
235	* pulses will do no harm. This is achieved by letting SDA follow SCL
236	* half a cycle later. Check the 'incomplete_write_byte' fault injector
237	* for details. Note that we must honour tsu:sto, 4us, but lets use 5us
238	* here for simplicity.
239	*/
240	bri->set_scl(adap, scl);
241	ndelay(RECOVERY_NDELAY);
242	if (bri->set_sda)
243	bri->set_sda(adap, scl);
244	ndelay(RECOVERY_NDELAY / `2`);
245
246	/*
247	* By this time SCL is high, as we need to give 9 falling-rising edges
248	*/
249	while (i++ < RECOVERY_CLK_CNT * `2`) {
250	if (scl) {
251	/ SCL shouldn't be low here /
252	if (!bri->get_scl(adap)) {
253	dev_err(&adap->dev,
254	"SCL is stuck low, exit recovery\n");
255	ret = -EBUSY;
256	break;
257	}
258	}
259
260	scl = !scl;
261	bri->set_scl(adap, scl);
262	/ Creating STOP again, see above /
263	if (scl) {
264	/ Honour minimum tsu:sto /
265	ndelay(RECOVERY_NDELAY);
266	} else {
267	/ Honour minimum tf and thd:dat /
268	ndelay(RECOVERY_NDELAY / `2`);
269	}
270	if (bri->set_sda)
271	bri->set_sda(adap, scl);
272	ndelay(RECOVERY_NDELAY / `2`);
273
274	if (scl) {
275	ret = i2c_generic_bus_free(adap);
276	if (ret == `0`)
277	break;
278	}
279	}
280
281	/ If we can't check bus status, assume recovery worked /
282	if (ret == -EOPNOTSUPP)
283	ret = `0`;
284
285	if (bri->unprepare_recovery)
286	bri->unprepare_recovery(adap);
287	if (bri->pinctrl)
288	pinctrl_select_state(p: bri->pinctrl, s: bri->pins_default);
289
290	return ret;
291	}
292	EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
293
294	int i2c_recover_bus(struct i2c_adapter *adap)
295	{
296	if (!adap->bus_recovery_info)
297	return -EBUSY;
298
299	dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
300	return adap->bus_recovery_info->recover_bus(adap);
301	}
302	EXPORT_SYMBOL_GPL(i2c_recover_bus);
303
304	static void i2c_gpio_init_pinctrl_recovery(struct i2c_adapter *adap)
305	{
306	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
307	struct device *dev = &adap->dev;
308	struct pinctrl *p = bri->pinctrl ?: dev_pinctrl(dev: dev->parent);
309
310	bri->pinctrl = p;
311
312	/*
313	* we can't change states without pinctrl, so remove the states if
314	* populated
315	*/
316	if (!p) {
317	bri->pins_default = NULL;
318	bri->pins_gpio = NULL;
319	return;
320	}
321
322	if (!bri->pins_default) {
323	bri->pins_default = pinctrl_lookup_state(p,
324	PINCTRL_STATE_DEFAULT);
325	if (IS_ERR(ptr: bri->pins_default)) {
326	dev_dbg(dev, PINCTRL_STATE_DEFAULT " state not found for GPIO recovery\n");
327	bri->pins_default = NULL;
328	}
329	}
330	if (!bri->pins_gpio) {
331	bri->pins_gpio = pinctrl_lookup_state(p, name: "gpio");
332	if (IS_ERR(ptr: bri->pins_gpio))
333	bri->pins_gpio = pinctrl_lookup_state(p, name: "recovery");
334
335	if (IS_ERR(ptr: bri->pins_gpio)) {
336	dev_dbg(dev, "no gpio or recovery state found for GPIO recovery\n");
337	bri->pins_gpio = NULL;
338	}
339	}
340
341	/ for pinctrl state changes, we need all the information /
342	if (bri->pins_default && bri->pins_gpio) {
343	dev_info(dev, "using pinctrl states for GPIO recovery");
344	} else {
345	bri->pinctrl = NULL;
346	bri->pins_default = NULL;
347	bri->pins_gpio = NULL;
348	}
349	}
350
351	static int i2c_gpio_init_generic_recovery(struct i2c_adapter *adap)
352	{
353	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
354	struct device *dev = &adap->dev;
355	struct gpio_desc *gpiod;
356	int ret = `0`;
357
358	/*
359	* don't touch the recovery information if the driver is not using
360	* generic SCL recovery
361	*/
362	if (bri->recover_bus && bri->recover_bus != i2c_generic_scl_recovery)
363	return `0`;
364
365	/*
366	* pins might be taken as GPIO, so we should inform pinctrl about
367	* this and move the state to GPIO
368	*/
369	if (bri->pinctrl)
370	pinctrl_select_state(p: bri->pinctrl, s: bri->pins_gpio);
371
372	/*
373	* if there is incomplete or no recovery information, see if generic
374	* GPIO recovery is available
375	*/
376	if (!bri->scl_gpiod) {
377	gpiod = devm_gpiod_get(dev, con_id: "scl", flags: GPIOD_OUT_HIGH_OPEN_DRAIN);
378	if (PTR_ERR(ptr: gpiod) == -EPROBE_DEFER) {
379	ret = -EPROBE_DEFER;
380	goto cleanup_pinctrl_state;
381	}
382	if (!IS_ERR(ptr: gpiod)) {
383	bri->scl_gpiod = gpiod;
384	bri->recover_bus = i2c_generic_scl_recovery;
385	dev_info(dev, "using generic GPIOs for recovery\n");
386	}
387	}
388
389	/ SDA GPIOD line is optional, so we care about DEFER only /
390	if (!bri->sda_gpiod) {
391	/*
392	* We have SCL. Pull SCL low and wait a bit so that SDA glitches
393	* have no effect.
394	*/
395	gpiod_direction_output(desc: bri->scl_gpiod, value: `0`);
396	udelay(usec: `10`);
397	gpiod = devm_gpiod_get(dev, con_id: "sda", flags: GPIOD_IN);
398
399	/ Wait a bit in case of a SDA glitch, and then release SCL. /
400	udelay(usec: `10`);
401	gpiod_direction_output(desc: bri->scl_gpiod, value: `1`);
402
403	if (PTR_ERR(ptr: gpiod) == -EPROBE_DEFER) {
404	ret = -EPROBE_DEFER;
405	goto cleanup_pinctrl_state;
406	}
407	if (!IS_ERR(ptr: gpiod))
408	bri->sda_gpiod = gpiod;
409	}
410
411	cleanup_pinctrl_state:
412	/ change the state of the pins back to their default state /
413	if (bri->pinctrl)
414	pinctrl_select_state(p: bri->pinctrl, s: bri->pins_default);
415
416	return ret;
417	}
418
419	static int i2c_gpio_init_recovery(struct i2c_adapter *adap)
420	{
421	i2c_gpio_init_pinctrl_recovery(adap);
422	return i2c_gpio_init_generic_recovery(adap);
423	}
424
425	static int i2c_init_recovery(struct i2c_adapter *adap)
426	{
427	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
428	bool is_error_level = true;
429	char *err_str;
430
431	if (!bri)
432	return `0`;
433
434	if (i2c_gpio_init_recovery(adap) == -EPROBE_DEFER)
435	return -EPROBE_DEFER;
436
437	if (!bri->recover_bus) {
438	err_str = "no suitable method provided";
439	is_error_level = false;
440	goto err;
441	}
442
443	if (bri->scl_gpiod && bri->recover_bus == i2c_generic_scl_recovery) {
444	bri->get_scl = get_scl_gpio_value;
445	bri->set_scl = set_scl_gpio_value;
446	if (bri->sda_gpiod) {
447	bri->get_sda = get_sda_gpio_value;
448	/ FIXME: add proper flag instead of '0' once available /
449	if (gpiod_get_direction(desc: bri->sda_gpiod) == `0`)
450	bri->set_sda = set_sda_gpio_value;
451	}
452	} else if (bri->recover_bus == i2c_generic_scl_recovery) {
453	/ Generic SCL recovery /
454	if (!bri->set_scl \|\| !bri->get_scl) {
455	err_str = "no {get\|set}_scl() found";
456	goto err;
457	}
458	if (!bri->set_sda && !bri->get_sda) {
459	err_str = "either get_sda() or set_sda() needed";
460	goto err;
461	}
462	}
463
464	return `0`;
465	err:
466	if (is_error_level)
467	dev_err(&adap->dev, "Not using recovery: %s\n", err_str);
468	else
469	dev_dbg(&adap->dev, "Not using recovery: %s\n", err_str);
470	adap->bus_recovery_info = NULL;
471
472	return -EINVAL;
473	}
474
475	static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
476	{
477	struct i2c_adapter *adap = client->adapter;
478	unsigned int irq;
479
480	if (!adap->host_notify_domain)
481	return -ENXIO;
482
483	if (client->flags & I2C_CLIENT_TEN)
484	return -EINVAL;
485
486	irq = irq_create_mapping(domain: adap->host_notify_domain, hwirq: client->addr);
487
488	return irq > `0` ? irq : -ENXIO;
489	}
490
491	static int i2c_device_probe(struct device *dev)
492	{
493	struct fwnode_handle *fwnode = dev_fwnode(dev);
494	struct i2c_client *client = i2c_verify_client(dev);
495	struct i2c_driver *driver;
496	bool do_power_on;
497	int status;
498
499	if (!client)
500	return `0`;
501
502	client->irq = client->init_irq;
503
504	if (!client->irq) {
505	int irq = -ENOENT;
506
507	if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
508	dev_dbg(dev, "Using Host Notify IRQ\n");
509	/ Keep adapter active when Host Notify is required /
510	pm_runtime_get_sync(dev: &client->adapter->dev);
511	irq = i2c_smbus_host_notify_to_irq(client);
512	} else if (is_of_node(fwnode)) {
513	irq = fwnode_irq_get_byname(fwnode, name: "irq");
514	if (irq == -EINVAL \|\| irq == -ENODATA)
515	irq = fwnode_irq_get(fwnode, index: `0`);
516	} else if (is_acpi_device_node(fwnode)) {
517	bool wake_capable;
518
519	irq = i2c_acpi_get_irq(client, wake_capable: &wake_capable);
520	if (irq > `0` && wake_capable)
521	client->flags \|= I2C_CLIENT_WAKE;
522	}
523	if (irq == -EPROBE_DEFER) {
524	status = dev_err_probe(dev, err: irq, fmt: "can't get irq\n");
525	goto put_sync_adapter;
526	}
527
528	if (irq < `0`)
529	irq = `0`;
530
531	client->irq = irq;
532	}
533
534	driver = to_i2c_driver(dev->driver);
535
536	/*
537	* An I2C ID table is not mandatory, if and only if, a suitable OF
538	* or ACPI ID table is supplied for the probing device.
539	*/
540	if (!driver->id_table &&
541	!acpi_driver_match_device(dev, drv: dev->driver) &&
542	!i2c_of_match_device(matches: dev->driver->of_match_table, client)) {
543	status = -ENODEV;
544	goto put_sync_adapter;
545	}
546
547	if (client->flags & I2C_CLIENT_WAKE) {
548	int wakeirq;
549
550	wakeirq = fwnode_irq_get_byname(fwnode, name: "wakeup");
551	if (wakeirq == -EPROBE_DEFER) {
552	status = dev_err_probe(dev, err: wakeirq, fmt: "can't get wakeirq\n");
553	goto put_sync_adapter;
554	}
555
556	device_init_wakeup(dev: &client->dev, enable: true);
557
558	if (wakeirq > `0` && wakeirq != client->irq)
559	status = dev_pm_set_dedicated_wake_irq(dev, irq: wakeirq);
560	else if (client->irq > `0`)
561	status = dev_pm_set_wake_irq(dev, irq: client->irq);
562	else
563	status = `0`;
564
565	if (status)
566	dev_warn(&client->dev, "failed to set up wakeup irq\n");
567	}
568
569	dev_dbg(dev, "probe\n");
570
571	status = of_clk_set_defaults(node: to_of_node(fwnode), clk_supplier: false);
572	if (status < `0`)
573	goto err_clear_wakeup_irq;
574
575	do_power_on = !i2c_acpi_waive_d0_probe(dev);
576	status = dev_pm_domain_attach(dev: &client->dev, PD_FLAG_DETACH_POWER_OFF \|
577	(do_power_on ? PD_FLAG_ATTACH_POWER_ON : `0`));
578	if (status)
579	goto err_clear_wakeup_irq;
580
581	client->devres_group_id = devres_open_group(dev: &client->dev, NULL,
582	GFP_KERNEL);
583	if (!client->devres_group_id) {
584	status = -ENOMEM;
585	goto err_clear_wakeup_irq;
586	}
587
588	client->debugfs = debugfs_create_dir(name: dev_name(dev: &client->dev),
589	parent: client->adapter->debugfs);
590
591	if (driver->probe)
592	status = driver->probe(client);
593	else
594	status = -EINVAL;
595
596	/*
597	* Note that we are not closing the devres group opened above so
598	* even resources that were attached to the device after probe is
599	* run are released when i2c_device_remove() is executed. This is
600	* needed as some drivers would allocate additional resources,
601	* for example when updating firmware.
602	*/
603
604	if (status)
605	goto err_release_driver_resources;
606
607	return `0`;
608
609	err_release_driver_resources:
610	debugfs_remove_recursive(dentry: client->debugfs);
611	devres_release_group(dev: &client->dev, id: client->devres_group_id);
612	err_clear_wakeup_irq:
613	dev_pm_clear_wake_irq(dev: &client->dev);
614	device_init_wakeup(dev: &client->dev, enable: false);
615	put_sync_adapter:
616	if (client->flags & I2C_CLIENT_HOST_NOTIFY)
617	pm_runtime_put_sync(dev: &client->adapter->dev);
618
619	return status;
620	}
621
622	static void i2c_device_remove(struct device *dev)
623	{
624	struct i2c_client *client = to_i2c_client(dev);
625	struct i2c_driver *driver;
626
627	driver = to_i2c_driver(dev->driver);
628	if (driver->remove) {
629	dev_dbg(dev, "remove\n");
630
631	driver->remove(client);
632	}
633
634	debugfs_remove_recursive(dentry: client->debugfs);
635
636	devres_release_group(dev: &client->dev, id: client->devres_group_id);
637
638	dev_pm_clear_wake_irq(dev: &client->dev);
639	device_init_wakeup(dev: &client->dev, enable: false);
640
641	client->irq = `0`;
642	if (client->flags & I2C_CLIENT_HOST_NOTIFY)
643	pm_runtime_put(dev: &client->adapter->dev);
644	}
645
646	static void i2c_device_shutdown(struct device *dev)
647	{
648	struct i2c_client *client = i2c_verify_client(dev);
649	struct i2c_driver *driver;
650
651	if (!client \|\| !dev->driver)
652	return;
653	driver = to_i2c_driver(dev->driver);
654	if (driver->shutdown)
655	driver->shutdown(client);
656	else if (client->irq > `0`)
657	disable_irq(irq: client->irq);
658	}
659
660	static void i2c_client_dev_release(struct device *dev)
661	{
662	kfree(to_i2c_client(dev));
663	}
664
665	static ssize_t
666	name_show(struct device dev, struct* device_attribute attr, char* *buf)
667	{
668	return sprintf(buf, fmt: "%s\n", dev->type == &i2c_client_type ?
669	to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
670	}
671	static DEVICE_ATTR_RO(name);
672
673	static ssize_t
674	modalias_show(struct device dev, struct* device_attribute attr, char* *buf)
675	{
676	struct i2c_client *client = to_i2c_client(dev);
677	int len;
678
679	len = of_device_modalias(dev, str: buf, PAGE_SIZE);
680	if (len != -ENODEV)
681	return len;
682
683	len = acpi_device_modalias(dev, buf, PAGE_SIZE - `1`);
684	if (len != -ENODEV)
685	return len;
686
687	return sprintf(buf, fmt: "%s%s\n", I2C_MODULE_PREFIX, client->name);
688	}
689	static DEVICE_ATTR_RO(modalias);
690
691	static struct attribute *i2c_dev_attrs[] = {
692	&dev_attr_name.attr,
693	/ modalias helps coldplug: modprobe $(cat .../modalias) /
694	&dev_attr_modalias.attr,
695	NULL
696	};
697	ATTRIBUTE_GROUPS(i2c_dev);
698
699	const struct bus_type i2c_bus_type = {
700	.name = "i2c",
701	.match = i2c_device_match,
702	.probe = i2c_device_probe,
703	.remove = i2c_device_remove,
704	.shutdown = i2c_device_shutdown,
705	};
706	EXPORT_SYMBOL_GPL(i2c_bus_type);
707
708	const struct device_type i2c_client_type = {
709	.groups = i2c_dev_groups,
710	.uevent = i2c_device_uevent,
711	.release = i2c_client_dev_release,
712	};
713	EXPORT_SYMBOL_GPL(i2c_client_type);
714
715
716	/**
717	* i2c_verify_client - return parameter as i2c_client, or NULL
718	* @dev: device, probably from some driver model iterator
719	*
720	* When traversing the driver model tree, perhaps using driver model
721	* iterators like @device_for_each_child(), you can't assume very much
722	* about the nodes you find. Use this function to avoid oopses caused
723	* by wrongly treating some non-I2C device as an i2c_client.
724	*/
725	struct i2c_client i2c_verify_client(struct* device *dev)
726	{
727	return (dev->type == &i2c_client_type)
728	? to_i2c_client(dev)
729	: NULL;
730	}
731	EXPORT_SYMBOL(i2c_verify_client);
732
733
734	/ Return a unique address which takes the flags of the client into account /
735	static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client)
736	{
737	unsigned short addr = client->addr;
738
739	/ For some client flags, add an arbitrary offset to avoid collisions /
740	if (client->flags & I2C_CLIENT_TEN)
741	addr \|= I2C_ADDR_OFFSET_TEN_BIT;
742
743	if (client->flags & I2C_CLIENT_SLAVE)
744	addr \|= I2C_ADDR_OFFSET_SLAVE;
745
746	return addr;
747	}
748
749	/ This is a permissive address validity check, I2C address map constraints*
750	* are purposely not enforced, except for the general call address. */
751	static int i2c_check_addr_validity(unsigned int addr, unsigned short flags)
752	{
753	if (flags & I2C_CLIENT_TEN) {
754	/ 10-bit address, all values are valid /
755	if (addr > `0x3ff`)
756	return -EINVAL;
757	} else {
758	/ 7-bit address, reject the general call address /
759	if (addr == `0x00` \|\| addr > `0x7f`)
760	return -EINVAL;
761	}
762	return `0`;
763	}
764
765	/ And this is a strict address validity check, used when probing. If a*
766	* device uses a reserved address, then it shouldn't be probed. 7-bit
767	* addressing is assumed, 10-bit address devices are rare and should be
768	* explicitly enumerated. */
769	int i2c_check_7bit_addr_validity_strict(unsigned short addr)
770	{
771	/*
772	* Reserved addresses per I2C specification:
773	* 0x00 General call address / START byte
774	* 0x01 CBUS address
775	* 0x02 Reserved for different bus format
776	* 0x03 Reserved for future purposes
777	* 0x04-0x07 Hs-mode master code
778	* 0x78-0x7b 10-bit slave addressing
779	* 0x7c-0x7f Reserved for future purposes
780	*/
781	if (addr < `0x08` \|\| addr > `0x77`)
782	return -EINVAL;
783	return `0`;
784	}
785
786	static int __i2c_check_addr_busy(struct device dev, void* *addrp)
787	{
788	struct i2c_client *client = i2c_verify_client(dev);
789	int addr = (int* *)addrp;
790
791	if (client && i2c_encode_flags_to_addr(client) == addr)
792	return -EBUSY;
793	return `0`;
794	}
795
796	/ walk up mux tree /
797	static int i2c_check_mux_parents(struct i2c_adapter adapter, int* addr)
798	{
799	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
800	int result;
801
802	result = device_for_each_child(parent: &adapter->dev, data: &addr,
803	fn: __i2c_check_addr_busy);
804
805	if (!result && parent)
806	result = i2c_check_mux_parents(adapter: parent, addr);
807
808	return result;
809	}
810
811	/ recurse down mux tree /
812	static int i2c_check_mux_children(struct device dev, void* *addrp)
813	{
814	int result;
815
816	if (dev->type == &i2c_adapter_type)
817	result = device_for_each_child(parent: dev, data: addrp,
818	fn: i2c_check_mux_children);
819	else
820	result = __i2c_check_addr_busy(dev, addrp);
821
822	return result;
823	}
824
825	static int i2c_check_addr_busy(struct i2c_adapter adapter, int* addr)
826	{
827	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
828	int result = `0`;
829
830	if (parent)
831	result = i2c_check_mux_parents(adapter: parent, addr);
832
833	if (!result)
834	result = device_for_each_child(parent: &adapter->dev, data: &addr,
835	fn: i2c_check_mux_children);
836
837	return result;
838	}
839
840	/**
841	* i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment
842	* @adapter: Target I2C bus segment
843	* @flags: I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT
844	* locks only this branch in the adapter tree
845	*/
846	static void i2c_adapter_lock_bus(struct i2c_adapter *adapter,
847	unsigned int flags)
848	{
849	rt_mutex_lock_nested(&adapter->bus_lock, i2c_adapter_depth(adapter));
850	}
851
852	/**
853	* i2c_adapter_trylock_bus - Try to get exclusive access to an I2C bus segment
854	* @adapter: Target I2C bus segment
855	* @flags: I2C_LOCK_ROOT_ADAPTER trylocks the root i2c adapter, I2C_LOCK_SEGMENT
856	* trylocks only this branch in the adapter tree
857	*/
858	static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter,
859	unsigned int flags)
860	{
861	return rt_mutex_trylock(lock: &adapter->bus_lock);
862	}
863
864	/**
865	* i2c_adapter_unlock_bus - Release exclusive access to an I2C bus segment
866	* @adapter: Target I2C bus segment
867	* @flags: I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENT
868	* unlocks only this branch in the adapter tree
869	*/
870	static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter,
871	unsigned int flags)
872	{
873	rt_mutex_unlock(lock: &adapter->bus_lock);
874	}
875
876	static void i2c_dev_set_name(struct i2c_adapter *adap,
877	struct i2c_client *client,
878	struct i2c_board_info const *info)
879	{
880	struct acpi_device *adev = ACPI_COMPANION(&client->dev);
881
882	if (info && info->dev_name) {
883	dev_set_name(dev: &client->dev, name: "i2c-%s", info->dev_name);
884	return;
885	}
886
887	if (adev) {
888	dev_set_name(dev: &client->dev, name: "i2c-%s", acpi_dev_name(adev));
889	return;
890	}
891
892	dev_set_name(dev: &client->dev, name: "%d-%04x", i2c_adapter_id(adap),
893	i2c_encode_flags_to_addr(client));
894	}
895
896	int i2c_dev_irq_from_resources(const struct resource *resources,
897	unsigned int num_resources)
898	{
899	struct irq_data *irqd;
900	int i;
901
902	for (i = `0`; i < num_resources; i++) {
903	const struct resource *r = &resources[i];
904
905	if (resource_type(res: r) != IORESOURCE_IRQ)
906	continue;
907
908	if (r->flags & IORESOURCE_BITS) {
909	irqd = irq_get_irq_data(irq: r->start);
910	if (!irqd)
911	break;
912
913	irqd_set_trigger_type(d: irqd, type: r->flags & IORESOURCE_BITS);
914	}
915
916	return r->start;
917	}
918
919	return `0`;
920	}
921
922	/*
923	* Serialize device instantiation in case it can be instantiated explicitly
924	* and by auto-detection
925	*/
926	static int i2c_lock_addr(struct i2c_adapter adap, unsigned* short addr,
927	unsigned short flags)
928	{
929	if (!(flags & I2C_CLIENT_TEN) &&
930	test_and_set_bit(nr: addr, addr: adap->addrs_in_instantiation))
931	return -EBUSY;
932
933	return `0`;
934	}
935
936	static void i2c_unlock_addr(struct i2c_adapter adap, unsigned* short addr,
937	unsigned short flags)
938	{
939	if (!(flags & I2C_CLIENT_TEN))
940	clear_bit(nr: addr, addr: adap->addrs_in_instantiation);
941	}
942
943	/**
944	* i2c_new_client_device - instantiate an i2c device
945	* @adap: the adapter managing the device
946	* @info: describes one I2C device; bus_num is ignored
947	* Context: can sleep
948	*
949	* Create an i2c device. Binding is handled through driver model
950	* probe()/remove() methods. A driver may be bound to this device when we
951	* return from this function, or any later moment (e.g. maybe hotplugging will
952	* load the driver module). This call is not appropriate for use by mainboard
953	* initialization logic, which usually runs during an arch_initcall() long
954	* before any i2c_adapter could exist.
955	*
956	* This returns the new i2c client, which may be saved for later use with
957	* i2c_unregister_device(); or an ERR_PTR to describe the error.
958	*/
959	struct i2c_client *
960	i2c_new_client_device(struct i2c_adapter adap, struct* i2c_board_info const *info)
961	{
962	struct fwnode_handle *fwnode = info->fwnode;
963	struct i2c_client *client;
964	bool need_put = false;
965	int status;
966
967	client = kzalloc(sizeof *client, GFP_KERNEL);
968	if (!client)
969	return ERR_PTR(error: -ENOMEM);
970
971	client->adapter = adap;
972
973	client->dev.platform_data = info->platform_data;
974	client->flags = info->flags;
975	client->addr = info->addr;
976
977	client->init_irq = info->irq;
978	if (!client->init_irq)
979	client->init_irq = i2c_dev_irq_from_resources(resources: info->resources,
980	num_resources: info->num_resources);
981
982	strscpy(client->name, info->type, sizeof(client->name));
983
984	status = i2c_check_addr_validity(addr: client->addr, flags: client->flags);
985	if (status) {
986	dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
987	client->flags & I2C_CLIENT_TEN ? `10` : `7`, client->addr);
988	goto out_err_silent;
989	}
990
991	status = i2c_lock_addr(adap, addr: client->addr, flags: client->flags);
992	if (status)
993	goto out_err_silent;
994
995	/ Check for address business /
996	status = i2c_check_addr_busy(adapter: adap, addr: i2c_encode_flags_to_addr(client));
997	if (status)
998	goto out_err;
999
1000	client->dev.parent = &client->adapter->dev;
1001	client->dev.bus = &i2c_bus_type;
1002	client->dev.type = &i2c_client_type;
1003
1004	device_enable_async_suspend(dev: &client->dev);
1005
1006	device_set_node(dev: &client->dev, fwnode: fwnode_handle_get(fwnode));
1007
1008	if (info->swnode) {
1009	status = device_add_software_node(dev: &client->dev, node: info->swnode);
1010	if (status) {
1011	dev_err(&adap->dev,
1012	"Failed to add software node to client %s: %d\n",
1013	client->name, status);
1014	goto out_err_put_fwnode;
1015	}
1016	}
1017
1018	i2c_dev_set_name(adap, client, info);
1019	status = device_register(dev: &client->dev);
1020	if (status)
1021	goto out_remove_swnode;
1022
1023	dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
1024	client->name, dev_name(&client->dev));
1025
1026	i2c_unlock_addr(adap, addr: client->addr, flags: client->flags);
1027
1028	return client;
1029
1030	out_remove_swnode:
1031	device_remove_software_node(dev: &client->dev);
1032	need_put = true;
1033	out_err_put_fwnode:
1034	fwnode_handle_put(fwnode);
1035	out_err:
1036	dev_err(&adap->dev,
1037	"Failed to register i2c client %s at 0x%02x (%d)\n",
1038	client->name, client->addr, status);
1039	i2c_unlock_addr(adap, addr: client->addr, flags: client->flags);
1040	out_err_silent:
1041	if (need_put)
1042	put_device(dev: &client->dev);
1043	else
1044	kfree(objp: client);
1045	return ERR_PTR(error: status);
1046	}
1047	EXPORT_SYMBOL_GPL(i2c_new_client_device);
1048
1049	/**
1050	* i2c_unregister_device - reverse effect of i2c_new_*_device()
1051	* @client: value returned from i2c_new_*_device()
1052	* Context: can sleep
1053	*/
1054	void i2c_unregister_device(struct i2c_client *client)
1055	{
1056	struct fwnode_handle *fwnode;
1057
1058	if (IS_ERR_OR_NULL(ptr: client))
1059	return;
1060
1061	fwnode = dev_fwnode(&client->dev);
1062	if (is_of_node(fwnode))
1063	of_node_clear_flag(n: to_of_node(fwnode), OF_POPULATED);
1064	else if (is_acpi_device_node(fwnode))
1065	acpi_device_clear_enumerated(to_acpi_device_node(fwnode));
1066
1067	/*
1068	* If the primary fwnode is a software node it is free-ed by
1069	* device_remove_software_node() below, avoid double-free.
1070	*/
1071	if (!is_software_node(fwnode))
1072	fwnode_handle_put(fwnode);
1073
1074	device_remove_software_node(dev: &client->dev);
1075	device_unregister(dev: &client->dev);
1076	}
1077	EXPORT_SYMBOL_GPL(i2c_unregister_device);
1078
1079	/**
1080	* i2c_find_device_by_fwnode() - find an i2c_client for the fwnode
1081	* @fwnode: &struct fwnode_handle corresponding to the &struct i2c_client
1082	*
1083	* Look up and return the &struct i2c_client corresponding to the @fwnode.
1084	* If no client can be found, or @fwnode is NULL, this returns NULL.
1085	*
1086	* The user must call put_device(&client->dev) once done with the i2c client.
1087	*/
1088	struct i2c_client i2c_find_device_by_fwnode(struct* fwnode_handle *fwnode)
1089	{
1090	struct i2c_client *client;
1091	struct device *dev;
1092
1093	if (!fwnode)
1094	return NULL;
1095
1096	dev = bus_find_device_by_fwnode(bus: &i2c_bus_type, fwnode);
1097	if (!dev)
1098	return NULL;
1099
1100	client = i2c_verify_client(dev);
1101	if (!client)
1102	put_device(dev);
1103
1104	return client;
1105	}
1106	EXPORT_SYMBOL(i2c_find_device_by_fwnode);
1107
1108
1109	static const struct i2c_device_id dummy_id[] = {
1110	{ "dummy", },
1111	{ .name: "smbus_host_notify", },
1112	{ }
1113	};
1114
1115	static int dummy_probe(struct i2c_client *client)
1116	{
1117	return `0`;
1118	}
1119
1120	static struct i2c_driver dummy_driver = {
1121	.driver.name = "dummy",
1122	.probe = dummy_probe,
1123	.id_table = dummy_id,
1124	};
1125
1126	/**
1127	* i2c_new_dummy_device - return a new i2c device bound to a dummy driver
1128	* @adapter: the adapter managing the device
1129	* @address: seven bit address to be used
1130	* Context: can sleep
1131	*
1132	* This returns an I2C client bound to the "dummy" driver, intended for use
1133	* with devices that consume multiple addresses. Examples of such chips
1134	* include various EEPROMS (like 24c04 and 24c08 models).
1135	*
1136	* These dummy devices have two main uses. First, most I2C and SMBus calls
1137	* except i2c_transfer() need a client handle; the dummy will be that handle.
1138	* And second, this prevents the specified address from being bound to a
1139	* different driver.
1140	*
1141	* This returns the new i2c client, which should be saved for later use with
1142	* i2c_unregister_device(); or an ERR_PTR to describe the error.
1143	*/
1144	struct i2c_client i2c_new_dummy_device(struct* i2c_adapter *adapter, u16 address)
1145	{
1146	struct i2c_board_info info = {
1147	I2C_BOARD_INFO("dummy", address),
1148	};
1149
1150	return i2c_new_client_device(adapter, &info);
1151	}
1152	EXPORT_SYMBOL_GPL(i2c_new_dummy_device);
1153
1154	static void devm_i2c_release_dummy(void *client)
1155	{
1156	i2c_unregister_device(client);
1157	}
1158
1159	/**
1160	* devm_i2c_new_dummy_device - return a new i2c device bound to a dummy driver
1161	* @dev: device the managed resource is bound to
1162	* @adapter: the adapter managing the device
1163	* @address: seven bit address to be used
1164	* Context: can sleep
1165	*
1166	* This is the device-managed version of @i2c_new_dummy_device. It returns the
1167	* new i2c client or an ERR_PTR in case of an error.
1168	*/
1169	struct i2c_client devm_i2c_new_dummy_device(struct* device *dev,
1170	struct i2c_adapter *adapter,
1171	u16 address)
1172	{
1173	struct i2c_client *client;
1174	int ret;
1175
1176	client = i2c_new_dummy_device(adapter, address);
1177	if (IS_ERR(ptr: client))
1178	return client;
1179
1180	ret = devm_add_action_or_reset(dev, devm_i2c_release_dummy, client);
1181	if (ret)
1182	return ERR_PTR(error: ret);
1183
1184	return client;
1185	}
1186	EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device);
1187
1188	/**
1189	* i2c_new_ancillary_device - Helper to get the instantiated secondary address
1190	* and create the associated device
1191	* @client: Handle to the primary client
1192	* @name: Handle to specify which secondary address to get
1193	* @default_addr: Used as a fallback if no secondary address was specified
1194	* Context: can sleep
1195	*
1196	* I2C clients can be composed of multiple I2C slaves bound together in a single
1197	* component. The I2C client driver then binds to the master I2C slave and needs
1198	* to create I2C dummy clients to communicate with all the other slaves.
1199	*
1200	* This function creates and returns an I2C dummy client whose I2C address is
1201	* retrieved from the platform firmware based on the given slave name. If no
1202	* address is specified by the firmware default_addr is used.
1203	*
1204	* On DT-based platforms the address is retrieved from the "reg" property entry
1205	* cell whose "reg-names" value matches the slave name.
1206	*
1207	* This returns the new i2c client, which should be saved for later use with
1208	* i2c_unregister_device(); or an ERR_PTR to describe the error.
1209	*/
1210	struct i2c_client i2c_new_ancillary_device(struct* i2c_client *client,
1211	const char *name,
1212	u16 default_addr)
1213	{
1214	struct device_node *np = client->dev.of_node;
1215	u32 addr = default_addr;
1216	int i;
1217
1218	i = of_property_match_string(np, propname: "reg-names", string: name);
1219	if (i >= `0`)
1220	of_property_read_u32_index(np, propname: "reg", index: i, out_value: &addr);
1221
1222	dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr);
1223	return i2c_new_dummy_device(client->adapter, addr);
1224	}
1225	EXPORT_SYMBOL_GPL(i2c_new_ancillary_device);
1226
1227	/ ------------------------------------------------------------------------- /
1228
1229	/ I2C bus adapters -- one roots each I2C or SMBUS segment /
1230
1231	static void i2c_adapter_dev_release(struct device *dev)
1232	{
1233	struct i2c_adapter *adap = to_i2c_adapter(dev);
1234	complete(&adap->dev_released);
1235	}
1236
1237	unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
1238	{
1239	unsigned int depth = `0`;
1240	struct device *parent;
1241
1242	for (parent = adapter->dev.parent; parent; parent = parent->parent)
1243	if (parent->type == &i2c_adapter_type)
1244	depth++;
1245
1246	WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES,
1247	"adapter depth exceeds lockdep subclass limit\n");
1248
1249	return depth;
1250	}
1251	EXPORT_SYMBOL_GPL(i2c_adapter_depth);
1252
1253	/*
1254	* Let users instantiate I2C devices through sysfs. This can be used when
1255	* platform initialization code doesn't contain the proper data for
1256	* whatever reason. Also useful for drivers that do device detection and
1257	* detection fails, either because the device uses an unexpected address,
1258	* or this is a compatible device with different ID register values.
1259	*
1260	* Parameter checking may look overzealous, but we really don't want
1261	* the user to provide incorrect parameters.
1262	*/
1263	static ssize_t
1264	new_device_store(struct device dev, struct* device_attribute *attr,
1265	const char *buf, size_t count)
1266	{
1267	struct i2c_adapter *adap = to_i2c_adapter(dev);
1268	struct i2c_board_info info;
1269	struct i2c_client *client;
1270	char *blank, end;
1271	int res;
1272
1273	memset(s: &info, c: `0`, n: sizeof(struct i2c_board_info));
1274
1275	blank = strchr(buf, `' '`);
1276	if (!blank) {
1277	dev_err(dev, "%s: Missing parameters\n", "new_device");
1278	return -EINVAL;
1279	}
1280	if (blank - buf > I2C_NAME_SIZE - `1`) {
1281	dev_err(dev, "%s: Invalid device name\n", "new_device");
1282	return -EINVAL;
1283	}
1284	memcpy(to: info.type, from: buf, len: blank - buf);
1285
1286	/ Parse remaining parameters, reject extra parameters /
1287	res = sscanf(++blank, "%hi%c", &info.addr, &end);
1288	if (res < `1`) {
1289	dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
1290	return -EINVAL;
1291	}
1292	if (res > `1` && end != `'\n'`) {
1293	dev_err(dev, "%s: Extra parameters\n", "new_device");
1294	return -EINVAL;
1295	}
1296
1297	if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) {
1298	info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT;
1299	info.flags \|= I2C_CLIENT_TEN;
1300	}
1301
1302	if (info.addr & I2C_ADDR_OFFSET_SLAVE) {
1303	info.addr &= ~I2C_ADDR_OFFSET_SLAVE;
1304	info.flags \|= I2C_CLIENT_SLAVE;
1305	}
1306
1307	client = i2c_new_client_device(adap, &info);
1308	if (IS_ERR(ptr: client))
1309	return PTR_ERR(ptr: client);
1310
1311	/ Keep track of the added device /
1312	mutex_lock(lock: &adap->userspace_clients_lock);
1313	list_add_tail(new: &client->detected, head: &adap->userspace_clients);
1314	mutex_unlock(lock: &adap->userspace_clients_lock);
1315	dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
1316	info.type, info.addr);
1317
1318	return count;
1319	}
1320	static DEVICE_ATTR_WO(new_device);
1321
1322	/*
1323	* And of course let the users delete the devices they instantiated, if
1324	* they got it wrong. This interface can only be used to delete devices
1325	* instantiated by i2c_sysfs_new_device above. This guarantees that we
1326	* don't delete devices to which some kernel code still has references.
1327	*
1328	* Parameter checking may look overzealous, but we really don't want
1329	* the user to delete the wrong device.
1330	*/
1331	static ssize_t
1332	delete_device_store(struct device dev, struct* device_attribute *attr,
1333	const char *buf, size_t count)
1334	{
1335	struct i2c_adapter *adap = to_i2c_adapter(dev);
1336	struct i2c_client client, next;
1337	unsigned short addr;
1338	char end;
1339	int res;
1340
1341	/ Parse parameters, reject extra parameters /
1342	res = sscanf(buf, "%hi%c", &addr, &end);
1343	if (res < `1`) {
1344	dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
1345	return -EINVAL;
1346	}
1347	if (res > `1` && end != `'\n'`) {
1348	dev_err(dev, "%s: Extra parameters\n", "delete_device");
1349	return -EINVAL;
1350	}
1351
1352	/ Make sure the device was added through sysfs /
1353	res = -ENOENT;
1354	mutex_lock_nested(&adap->userspace_clients_lock,
1355	i2c_adapter_depth(adap));
1356	list_for_each_entry_safe(client, next, &adap->userspace_clients,
1357	detected) {
1358	if (i2c_encode_flags_to_addr(client) == addr) {
1359	dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
1360	"delete_device", client->name, client->addr);
1361
1362	list_del(entry: &client->detected);
1363	i2c_unregister_device(client);
1364	res = count;
1365	break;
1366	}
1367	}
1368	mutex_unlock(lock: &adap->userspace_clients_lock);
1369
1370	if (res < `0`)
1371	dev_err(dev, "%s: Can't find device in list\n",
1372	"delete_device");
1373	return res;
1374	}
1375	static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
1376	delete_device_store);
1377
1378	static struct attribute *i2c_adapter_attrs[] = {
1379	&dev_attr_name.attr,
1380	&dev_attr_new_device.attr,
1381	&dev_attr_delete_device.attr,
1382	NULL
1383	};
1384	ATTRIBUTE_GROUPS(i2c_adapter);
1385
1386	const struct device_type i2c_adapter_type = {
1387	.groups = i2c_adapter_groups,
1388	.release = i2c_adapter_dev_release,
1389	};
1390	EXPORT_SYMBOL_GPL(i2c_adapter_type);
1391
1392	/**
1393	* i2c_verify_adapter - return parameter as i2c_adapter or NULL
1394	* @dev: device, probably from some driver model iterator
1395	*
1396	* When traversing the driver model tree, perhaps using driver model
1397	* iterators like @device_for_each_child(), you can't assume very much
1398	* about the nodes you find. Use this function to avoid oopses caused
1399	* by wrongly treating some non-I2C device as an i2c_adapter.
1400	*/
1401	struct i2c_adapter i2c_verify_adapter(struct* device *dev)
1402	{
1403	return (dev->type == &i2c_adapter_type)
1404	? to_i2c_adapter(dev)
1405	: NULL;
1406	}
1407	EXPORT_SYMBOL(i2c_verify_adapter);
1408
1409	static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
1410	{
1411	struct i2c_devinfo *devinfo;
1412
1413	down_read(sem: &__i2c_board_lock);
1414	list_for_each_entry(devinfo, &__i2c_board_list, list) {
1415	if (devinfo->busnum == adapter->nr &&
1416	IS_ERR(ptr: i2c_new_client_device(adapter, &devinfo->board_info)))
1417	dev_err(&adapter->dev,
1418	"Can't create device at 0x%02x\n",
1419	devinfo->board_info.addr);
1420	}
1421	up_read(sem: &__i2c_board_lock);
1422	}
1423
1424	static int i2c_do_add_adapter(struct i2c_driver *driver,
1425	struct i2c_adapter *adap)
1426	{
1427	/ Detect supported devices on that bus, and instantiate them /
1428	i2c_detect(adapter: adap, driver);
1429
1430	return `0`;
1431	}
1432
1433	static int __process_new_adapter(struct device_driver d, void* *data)
1434	{
1435	return i2c_do_add_adapter(to_i2c_driver(d), adap: data);
1436	}
1437
1438	static const struct i2c_lock_operations i2c_adapter_lock_ops = {
1439	.lock_bus = i2c_adapter_lock_bus,
1440	.trylock_bus = i2c_adapter_trylock_bus,
1441	.unlock_bus = i2c_adapter_unlock_bus,
1442	};
1443
1444	static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap)
1445	{
1446	struct irq_domain *domain = adap->host_notify_domain;
1447	irq_hw_number_t hwirq;
1448
1449	if (!domain)
1450	return;
1451
1452	for (hwirq = `0` ; hwirq < I2C_ADDR_7BITS_COUNT ; hwirq++)
1453	irq_dispose_mapping(virq: irq_find_mapping(domain, hwirq));
1454
1455	irq_domain_remove(domain);
1456	adap->host_notify_domain = NULL;
1457	}
1458
1459	static int i2c_host_notify_irq_map(struct irq_domain *h,
1460	unsigned int virq,
1461	irq_hw_number_t hw_irq_num)
1462	{
1463	irq_set_chip_and_handler(irq: virq, chip: &dummy_irq_chip, handle: handle_simple_irq);
1464
1465	return `0`;
1466	}
1467
1468	static const struct irq_domain_ops i2c_host_notify_irq_ops = {
1469	.map = i2c_host_notify_irq_map,
1470	};
1471
1472	static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap)
1473	{
1474	struct irq_domain *domain;
1475
1476	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY))
1477	return `0`;
1478
1479	domain = irq_domain_create_linear(fwnode: adap->dev.parent->fwnode,
1480	I2C_ADDR_7BITS_COUNT,
1481	ops: &i2c_host_notify_irq_ops, host_data: adap);
1482	if (!domain)
1483	return -ENOMEM;
1484
1485	adap->host_notify_domain = domain;
1486
1487	return `0`;
1488	}
1489
1490	/**
1491	* i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct
1492	* I2C client.
1493	* @adap: the adapter
1494	* @addr: the I2C address of the notifying device
1495	* Context: can't sleep
1496	*
1497	* Helper function to be called from an I2C bus driver's interrupt
1498	* handler. It will schedule the Host Notify IRQ.
1499	*/
1500	int i2c_handle_smbus_host_notify(struct i2c_adapter adap, unsigned* short addr)
1501	{
1502	int irq;
1503
1504	if (!adap)
1505	return -EINVAL;
1506
1507	dev_dbg(&adap->dev, "Detected HostNotify from address 0x%02x", addr);
1508
1509	irq = irq_find_mapping(domain: adap->host_notify_domain, hwirq: addr);
1510	if (irq <= `0`)
1511	return -ENXIO;
1512
1513	generic_handle_irq_safe(irq);
1514
1515	return `0`;
1516	}
1517	EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify);
1518
1519	static int i2c_register_adapter(struct i2c_adapter *adap)
1520	{
1521	int res = -EINVAL;
1522
1523	/ Can't register until after driver model init /
1524	if (WARN_ON(!is_registered)) {
1525	res = -EAGAIN;
1526	goto out_list;
1527	}
1528
1529	/ Sanity checks /
1530	if (WARN(!adap->name[`0`], "i2c adapter has no name"))
1531	goto out_list;
1532
1533	if (!adap->algo) {
1534	pr_err("adapter '%s': no algo supplied!\n", adap->name);
1535	goto out_list;
1536	}
1537
1538	if (!adap->lock_ops)
1539	adap->lock_ops = &i2c_adapter_lock_ops;
1540
1541	adap->locked_flags = `0`;
1542	rt_mutex_init(&adap->bus_lock);
1543	rt_mutex_init(&adap->mux_lock);
1544	mutex_init(&adap->userspace_clients_lock);
1545	INIT_LIST_HEAD(list: &adap->userspace_clients);
1546
1547	/ Set default timeout to 1 second if not already set /
1548	if (adap->timeout == `0`)
1549	adap->timeout = HZ;
1550
1551	/ register soft irqs for Host Notify /
1552	res = i2c_setup_host_notify_irq_domain(adap);
1553	if (res) {
1554	pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n",
1555	adap->name, res);
1556	goto out_list;
1557	}
1558
1559	dev_set_name(dev: &adap->dev, name: "i2c-%d", adap->nr);
1560	adap->dev.bus = &i2c_bus_type;
1561	adap->dev.type = &i2c_adapter_type;
1562	device_initialize(dev: &adap->dev);
1563
1564	/*
1565	* This adapter can be used as a parent immediately after device_add(),
1566	* setup runtime-pm (especially ignore-children) before hand.
1567	*/
1568	device_enable_async_suspend(dev: &adap->dev);
1569	pm_runtime_no_callbacks(dev: &adap->dev);
1570	pm_suspend_ignore_children(dev: &adap->dev, enable: true);
1571	pm_runtime_enable(dev: &adap->dev);
1572
1573	res = device_add(dev: &adap->dev);
1574	if (res) {
1575	pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
1576	put_device(dev: &adap->dev);
1577	goto out_list;
1578	}
1579
1580	adap->debugfs = debugfs_create_dir(name: dev_name(dev: &adap->dev), parent: i2c_debugfs_root);
1581
1582	res = i2c_setup_smbus_alert(adap);
1583	if (res)
1584	goto out_reg;
1585
1586	res = i2c_init_recovery(adap);
1587	if (res == -EPROBE_DEFER)
1588	goto out_reg;
1589
1590	dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
1591
1592	/ create pre-declared device nodes /
1593	of_i2c_register_devices(adap);
1594	i2c_acpi_install_space_handler(adapter: adap);
1595	i2c_acpi_register_devices(adap);
1596
1597	if (adap->nr < __i2c_first_dynamic_bus_num)
1598	i2c_scan_static_board_info(adapter: adap);
1599
1600	/ Notify drivers /
1601	mutex_lock(lock: &core_lock);
1602	bus_for_each_drv(bus: &i2c_bus_type, NULL, data: adap, fn: __process_new_adapter);
1603	mutex_unlock(lock: &core_lock);
1604
1605	return `0`;
1606
1607	out_reg:
1608	debugfs_remove_recursive(dentry: adap->debugfs);
1609	init_completion(x: &adap->dev_released);
1610	device_unregister(dev: &adap->dev);
1611	wait_for_completion(&adap->dev_released);
1612	out_list:
1613	mutex_lock(lock: &core_lock);
1614	idr_remove(&i2c_adapter_idr, id: adap->nr);
1615	mutex_unlock(lock: &core_lock);
1616	return res;
1617	}
1618
1619	/**
1620	* __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
1621	* @adap: the adapter to register (with adap->nr initialized)
1622	* Context: can sleep
1623	*
1624	* See i2c_add_numbered_adapter() for details.
1625	*/
1626	static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
1627	{
1628	int id;
1629
1630	mutex_lock(lock: &core_lock);
1631	id = idr_alloc(&i2c_adapter_idr, ptr: adap, start: adap->nr, end: adap->nr + `1`, GFP_KERNEL);
1632	mutex_unlock(lock: &core_lock);
1633	if (WARN(id < `0`, "couldn't get idr"))
1634	return id == -ENOSPC ? -EBUSY : id;
1635
1636	return i2c_register_adapter(adap);
1637	}
1638
1639	/**
1640	* i2c_add_adapter - declare i2c adapter, use dynamic bus number
1641	* @adapter: the adapter to add
1642	* Context: can sleep
1643	*
1644	* This routine is used to declare an I2C adapter when its bus number
1645	* doesn't matter or when its bus number is specified by an dt alias.
1646	* Examples of bases when the bus number doesn't matter: I2C adapters
1647	* dynamically added by USB links or PCI plugin cards.
1648	*
1649	* When this returns zero, a new bus number was allocated and stored
1650	* in adap->nr, and the specified adapter became available for clients.
1651	* Otherwise, a negative errno value is returned.
1652	*/
1653	int i2c_add_adapter(struct i2c_adapter *adapter)
1654	{
1655	struct device *dev = &adapter->dev;
1656	int id;
1657
1658	id = of_alias_get_id(np: dev->of_node, stem: "i2c");
1659	if (id >= `0`) {
1660	adapter->nr = id;
1661	return __i2c_add_numbered_adapter(adap: adapter);
1662	}
1663
1664	mutex_lock(lock: &core_lock);
1665	id = idr_alloc(&i2c_adapter_idr, ptr: adapter,
1666	start: __i2c_first_dynamic_bus_num, end: `0`, GFP_KERNEL);
1667	mutex_unlock(lock: &core_lock);
1668	if (WARN(id < `0`, "couldn't get idr"))
1669	return id;
1670
1671	adapter->nr = id;
1672
1673	return i2c_register_adapter(adap: adapter);
1674	}
1675	EXPORT_SYMBOL(i2c_add_adapter);
1676
1677	/**
1678	* i2c_add_numbered_adapter - declare i2c adapter, use static bus number
1679	* @adap: the adapter to register (with adap->nr initialized)
1680	* Context: can sleep
1681	*
1682	* This routine is used to declare an I2C adapter when its bus number
1683	* matters. For example, use it for I2C adapters from system-on-chip CPUs,
1684	* or otherwise built in to the system's mainboard, and where i2c_board_info
1685	* is used to properly configure I2C devices.
1686	*
1687	* If the requested bus number is set to -1, then this function will behave
1688	* identically to i2c_add_adapter, and will dynamically assign a bus number.
1689	*
1690	* If no devices have pre-been declared for this bus, then be sure to
1691	* register the adapter before any dynamically allocated ones. Otherwise
1692	* the required bus ID may not be available.
1693	*
1694	* When this returns zero, the specified adapter became available for
1695	* clients using the bus number provided in adap->nr. Also, the table
1696	* of I2C devices pre-declared using i2c_register_board_info() is scanned,
1697	* and the appropriate driver model device nodes are created. Otherwise, a
1698	* negative errno value is returned.
1699	*/
1700	int i2c_add_numbered_adapter(struct i2c_adapter *adap)
1701	{
1702	if (adap->nr == -`1`) / -1 means dynamically assign bus id /
1703	return i2c_add_adapter(adap);
1704
1705	return __i2c_add_numbered_adapter(adap);
1706	}
1707	EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
1708
1709	static void i2c_do_del_adapter(struct i2c_driver *driver,
1710	struct i2c_adapter *adapter)
1711	{
1712	struct i2c_client client, _n;
1713
1714	/ Remove the devices we created ourselves as the result of hardware*
1715	* probing (using a driver's detect method) */
1716	list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1717	if (client->adapter == adapter) {
1718	dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1719	client->name, client->addr);
1720	list_del(entry: &client->detected);
1721	i2c_unregister_device(client);
1722	}
1723	}
1724	}
1725
1726	static int __unregister_client(struct device dev, void* *dummy)
1727	{
1728	struct i2c_client *client = i2c_verify_client(dev);
1729	if (client && strcmp(client->name, "dummy"))
1730	i2c_unregister_device(client);
1731	return `0`;
1732	}
1733
1734	static int __unregister_dummy(struct device dev, void* *dummy)
1735	{
1736	struct i2c_client *client = i2c_verify_client(dev);
1737	i2c_unregister_device(client);
1738	return `0`;
1739	}
1740
1741	static int __process_removed_adapter(struct device_driver d, void* *data)
1742	{
1743	i2c_do_del_adapter(to_i2c_driver(d), adapter: data);
1744	return `0`;
1745	}
1746
1747	/**
1748	* i2c_del_adapter - unregister I2C adapter
1749	* @adap: the adapter being unregistered
1750	* Context: can sleep
1751	*
1752	* This unregisters an I2C adapter which was previously registered
1753	* by @i2c_add_adapter or @i2c_add_numbered_adapter.
1754	*/
1755	void i2c_del_adapter(struct i2c_adapter *adap)
1756	{
1757	struct i2c_adapter *found;
1758	struct i2c_client client, next;
1759
1760	/ First make sure that this adapter was ever added /
1761	mutex_lock(lock: &core_lock);
1762	found = idr_find(&i2c_adapter_idr, id: adap->nr);
1763	mutex_unlock(lock: &core_lock);
1764	if (found != adap) {
1765	pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
1766	return;
1767	}
1768
1769	i2c_acpi_remove_space_handler(adapter: adap);
1770	/ Tell drivers about this removal /
1771	mutex_lock(lock: &core_lock);
1772	bus_for_each_drv(bus: &i2c_bus_type, NULL, data: adap,
1773	fn: __process_removed_adapter);
1774	mutex_unlock(lock: &core_lock);
1775
1776	/ Remove devices instantiated from sysfs /
1777	mutex_lock_nested(&adap->userspace_clients_lock,
1778	i2c_adapter_depth(adap));
1779	list_for_each_entry_safe(client, next, &adap->userspace_clients,
1780	detected) {
1781	dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1782	client->addr);
1783	list_del(entry: &client->detected);
1784	i2c_unregister_device(client);
1785	}
1786	mutex_unlock(lock: &adap->userspace_clients_lock);
1787
1788	/ Detach any active clients. This can't fail, thus we do not*
1789	* check the returned value. This is a two-pass process, because
1790	* we can't remove the dummy devices during the first pass: they
1791	* could have been instantiated by real devices wishing to clean
1792	* them up properly, so we give them a chance to do that first. */
1793	device_for_each_child(parent: &adap->dev, NULL, fn: __unregister_client);
1794	device_for_each_child(parent: &adap->dev, NULL, fn: __unregister_dummy);
1795
1796	/ device name is gone after device_unregister /
1797	dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1798
1799	pm_runtime_disable(dev: &adap->dev);
1800
1801	i2c_host_notify_irq_teardown(adap);
1802
1803	debugfs_remove_recursive(dentry: adap->debugfs);
1804
1805	/ wait until all references to the device are gone*
1806	*
1807	* FIXME: This is old code and should ideally be replaced by an
1808	* alternative which results in decoupling the lifetime of the struct
1809	* device from the i2c_adapter, like spi or netdev do. Any solution
1810	* should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled!
1811	*/
1812	init_completion(x: &adap->dev_released);
1813	device_unregister(dev: &adap->dev);
1814	wait_for_completion(&adap->dev_released);
1815
1816	/ free bus id /
1817	mutex_lock(lock: &core_lock);
1818	idr_remove(&i2c_adapter_idr, id: adap->nr);
1819	mutex_unlock(lock: &core_lock);
1820
1821	/ Clear the device structure in case this adapter is ever going to be*
1822	added again /*
1823	memset(s: &adap->dev, c: `0`, n: sizeof(adap->dev));
1824	}
1825	EXPORT_SYMBOL(i2c_del_adapter);
1826
1827	static void devm_i2c_del_adapter(void *adapter)
1828	{
1829	i2c_del_adapter(adapter);
1830	}
1831
1832	/**
1833	* devm_i2c_add_adapter - device-managed variant of i2c_add_adapter()
1834	* @dev: managing device for adding this I2C adapter
1835	* @adapter: the adapter to add
1836	* Context: can sleep
1837	*
1838	* Add adapter with dynamic bus number, same with i2c_add_adapter()
1839	* but the adapter will be auto deleted on driver detach.
1840	*/
1841	int devm_i2c_add_adapter(struct device dev, struct* i2c_adapter *adapter)
1842	{
1843	int ret;
1844
1845	ret = i2c_add_adapter(adapter);
1846	if (ret)
1847	return ret;
1848
1849	return devm_add_action_or_reset(dev, devm_i2c_del_adapter, adapter);
1850	}
1851	EXPORT_SYMBOL_GPL(devm_i2c_add_adapter);
1852
1853	static int i2c_dev_or_parent_fwnode_match(struct device dev, const* void *data)
1854	{
1855	if (dev_fwnode(dev) == data)
1856	return `1`;
1857
1858	if (dev->parent && dev_fwnode(dev->parent) == data)
1859	return `1`;
1860
1861	return `0`;
1862	}
1863
1864	/**
1865	* i2c_find_adapter_by_fwnode() - find an i2c_adapter for the fwnode
1866	* @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter
1867	*
1868	* Look up and return the &struct i2c_adapter corresponding to the @fwnode.
1869	* If no adapter can be found, or @fwnode is NULL, this returns NULL.
1870	*
1871	* The user must call put_device(&adapter->dev) once done with the i2c adapter.
1872	*/
1873	struct i2c_adapter i2c_find_adapter_by_fwnode(struct* fwnode_handle *fwnode)
1874	{
1875	struct i2c_adapter *adapter;
1876	struct device *dev;
1877
1878	if (!fwnode)
1879	return NULL;
1880
1881	dev = bus_find_device(bus: &i2c_bus_type, NULL, data: fwnode,
1882	match: i2c_dev_or_parent_fwnode_match);
1883	if (!dev)
1884	return NULL;
1885
1886	adapter = i2c_verify_adapter(dev);
1887	if (!adapter)
1888	put_device(dev);
1889
1890	return adapter;
1891	}
1892	EXPORT_SYMBOL(i2c_find_adapter_by_fwnode);
1893
1894	/**
1895	* i2c_get_adapter_by_fwnode() - find an i2c_adapter for the fwnode
1896	* @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter
1897	*
1898	* Look up and return the &struct i2c_adapter corresponding to the @fwnode,
1899	* and increment the adapter module's use count. If no adapter can be found,
1900	* or @fwnode is NULL, this returns NULL.
1901	*
1902	* The user must call i2c_put_adapter(adapter) once done with the i2c adapter.
1903	* Note that this is different from i2c_find_adapter_by_node().
1904	*/
1905	struct i2c_adapter i2c_get_adapter_by_fwnode(struct* fwnode_handle *fwnode)
1906	{
1907	struct i2c_adapter *adapter;
1908
1909	adapter = i2c_find_adapter_by_fwnode(fwnode);
1910	if (!adapter)
1911	return NULL;
1912
1913	if (!try_module_get(module: adapter->owner)) {
1914	put_device(dev: &adapter->dev);
1915	adapter = NULL;
1916	}
1917
1918	return adapter;
1919	}
1920	EXPORT_SYMBOL(i2c_get_adapter_by_fwnode);
1921
1922	static void i2c_parse_timing(struct device dev, char* prop_name, u32 cur_val_p,
1923	u32 def_val, bool use_def)
1924	{
1925	int ret;
1926
1927	ret = device_property_read_u32(dev, propname: prop_name, val: cur_val_p);
1928	if (ret && use_def)
1929	*cur_val_p = def_val;
1930
1931	dev_dbg(dev, "%s: %u\n", prop_name, *cur_val_p);
1932	}
1933
1934	/**
1935	* i2c_parse_fw_timings - get I2C related timing parameters from firmware
1936	* @dev: The device to scan for I2C timing properties
1937	* @t: the i2c_timings struct to be filled with values
1938	* @use_defaults: bool to use sane defaults derived from the I2C specification
1939	* when properties are not found, otherwise don't update
1940	*
1941	* Scan the device for the generic I2C properties describing timing parameters
1942	* for the signal and fill the given struct with the results. If a property was
1943	* not found and use_defaults was true, then maximum timings are assumed which
1944	* are derived from the I2C specification. If use_defaults is not used, the
1945	* results will be as before, so drivers can apply their own defaults before
1946	* calling this helper. The latter is mainly intended for avoiding regressions
1947	* of existing drivers which want to switch to this function. New drivers
1948	* almost always should use the defaults.
1949	*/
1950	void i2c_parse_fw_timings(struct device dev, struct* i2c_timings *t, bool use_defaults)
1951	{
1952	bool u = use_defaults;
1953	u32 d;
1954
1955	i2c_parse_timing(dev, prop_name: "clock-frequency", cur_val_p: &t->bus_freq_hz,
1956	I2C_MAX_STANDARD_MODE_FREQ, use_def: u);
1957
1958	d = t->bus_freq_hz <= I2C_MAX_STANDARD_MODE_FREQ ? `1000` :
1959	t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? `300` : `120`;
1960	i2c_parse_timing(dev, prop_name: "i2c-scl-rising-time-ns", cur_val_p: &t->scl_rise_ns, def_val: d, use_def: u);
1961
1962	d = t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? `300` : `120`;
1963	i2c_parse_timing(dev, prop_name: "i2c-scl-falling-time-ns", cur_val_p: &t->scl_fall_ns, def_val: d, use_def: u);
1964
1965	i2c_parse_timing(dev, prop_name: "i2c-scl-internal-delay-ns",
1966	cur_val_p: &t->scl_int_delay_ns, def_val: `0`, use_def: u);
1967	i2c_parse_timing(dev, prop_name: "i2c-sda-falling-time-ns", cur_val_p: &t->sda_fall_ns,
1968	def_val: t->scl_fall_ns, use_def: u);
1969	i2c_parse_timing(dev, prop_name: "i2c-sda-hold-time-ns", cur_val_p: &t->sda_hold_ns, def_val: `0`, use_def: u);
1970	i2c_parse_timing(dev, prop_name: "i2c-digital-filter-width-ns",
1971	cur_val_p: &t->digital_filter_width_ns, def_val: `0`, use_def: u);
1972	i2c_parse_timing(dev, prop_name: "i2c-analog-filter-cutoff-frequency",
1973	cur_val_p: &t->analog_filter_cutoff_freq_hz, def_val: `0`, use_def: u);
1974	}
1975	EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
1976
1977	/ ------------------------------------------------------------------------- /
1978
1979	int i2c_for_each_dev(void data, int* (fn)(struct* device dev, void* *data))
1980	{
1981	int res;
1982
1983	mutex_lock(lock: &core_lock);
1984	res = bus_for_each_dev(bus: &i2c_bus_type, NULL, data, fn);
1985	mutex_unlock(lock: &core_lock);
1986
1987	return res;
1988	}
1989	EXPORT_SYMBOL_GPL(i2c_for_each_dev);
1990
1991	static int __process_new_driver(struct device dev, void* *data)
1992	{
1993	if (dev->type != &i2c_adapter_type)
1994	return `0`;
1995	return i2c_do_add_adapter(driver: data, to_i2c_adapter(dev));
1996	}
1997
1998	/*
1999	* An i2c_driver is used with one or more i2c_client (device) nodes to access
2000	* i2c slave chips, on a bus instance associated with some i2c_adapter.
2001	*/
2002
2003	int i2c_register_driver(struct module owner, struct* i2c_driver *driver)
2004	{
2005	int res;
2006
2007	/ Can't register until after driver model init /
2008	if (WARN_ON(!is_registered))
2009	return -EAGAIN;
2010
2011	/ add the driver to the list of i2c drivers in the driver core /
2012	driver->driver.owner = owner;
2013	driver->driver.bus = &i2c_bus_type;
2014	INIT_LIST_HEAD(list: &driver->clients);
2015
2016	/ When registration returns, the driver core*
2017	* will have called probe() for all matching-but-unbound devices.
2018	*/
2019	res = driver_register(drv: &driver->driver);
2020	if (res)
2021	return res;
2022
2023	pr_debug("driver [%s] registered\n", driver->driver.name);
2024
2025	/ Walk the adapters that are already present /
2026	i2c_for_each_dev(driver, __process_new_driver);
2027
2028	return `0`;
2029	}
2030	EXPORT_SYMBOL(i2c_register_driver);
2031
2032	static int __process_removed_driver(struct device dev, void* *data)
2033	{
2034	if (dev->type == &i2c_adapter_type)
2035	i2c_do_del_adapter(driver: data, to_i2c_adapter(dev));
2036	return `0`;
2037	}
2038
2039	/**
2040	* i2c_del_driver - unregister I2C driver
2041	* @driver: the driver being unregistered
2042	* Context: can sleep
2043	*/
2044	void i2c_del_driver(struct i2c_driver *driver)
2045	{
2046	i2c_for_each_dev(driver, __process_removed_driver);
2047
2048	driver_unregister(drv: &driver->driver);
2049	pr_debug("driver [%s] unregistered\n", driver->driver.name);
2050	}
2051	EXPORT_SYMBOL(i2c_del_driver);
2052
2053	/ ------------------------------------------------------------------------- /
2054
2055	struct i2c_cmd_arg {
2056	unsigned cmd;
2057	void *arg;
2058	};
2059
2060	static int i2c_cmd(struct device dev, void* *_arg)
2061	{
2062	struct i2c_client *client = i2c_verify_client(dev);
2063	struct i2c_cmd_arg *arg = _arg;
2064	struct i2c_driver *driver;
2065
2066	if (!client \|\| !client->dev.driver)
2067	return `0`;
2068
2069	driver = to_i2c_driver(client->dev.driver);
2070	if (driver->command)
2071	driver->command(client, arg->cmd, arg->arg);
2072	return `0`;
2073	}
2074
2075	void i2c_clients_command(struct i2c_adapter adap, unsigned* int cmd, void *arg)
2076	{
2077	struct i2c_cmd_arg cmd_arg;
2078
2079	cmd_arg.cmd = cmd;
2080	cmd_arg.arg = arg;
2081	device_for_each_child(parent: &adap->dev, data: &cmd_arg, fn: i2c_cmd);
2082	}
2083	EXPORT_SYMBOL(i2c_clients_command);
2084
2085	static int __init i2c_init(void)
2086	{
2087	int retval;
2088
2089	retval = of_alias_get_highest_id(stem: "i2c");
2090
2091	down_write(sem: &__i2c_board_lock);
2092	if (retval >= __i2c_first_dynamic_bus_num)
2093	__i2c_first_dynamic_bus_num = retval + `1`;
2094	up_write(sem: &__i2c_board_lock);
2095
2096	retval = bus_register(bus: &i2c_bus_type);
2097	if (retval)
2098	return retval;
2099
2100	is_registered = true;
2101
2102	i2c_debugfs_root = debugfs_create_dir(name: "i2c", NULL);
2103
2104	retval = i2c_add_driver(&dummy_driver);
2105	if (retval)
2106	goto class_err;
2107
2108	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2109	WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier));
2110	if (IS_ENABLED(CONFIG_ACPI))
2111	WARN_ON(acpi_reconfig_notifier_register(&i2c_acpi_notifier));
2112
2113	return `0`;
2114
2115	class_err:
2116	is_registered = false;
2117	bus_unregister(bus: &i2c_bus_type);
2118	return retval;
2119	}
2120
2121	static void __exit i2c_exit(void)
2122	{
2123	if (IS_ENABLED(CONFIG_ACPI))
2124	WARN_ON(acpi_reconfig_notifier_unregister(&i2c_acpi_notifier));
2125	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2126	WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier));
2127	i2c_del_driver(&dummy_driver);
2128	debugfs_remove_recursive(dentry: i2c_debugfs_root);
2129	bus_unregister(bus: &i2c_bus_type);
2130	tracepoint_synchronize_unregister();
2131	}
2132
2133	/ We must initialize early, because some subsystems register i2c drivers*
2134	* in subsys_initcall() code, but are linked (and initialized) before i2c.
2135	*/
2136	postcore_initcall(i2c_init);
2137	module_exit(i2c_exit);
2138
2139	/ ----------------------------------------------------*
2140	* the functional interface to the i2c busses.
2141	* ----------------------------------------------------
2142	*/
2143
2144	/ Check if val is exceeding the quirk IFF quirk is non 0 /
2145	#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
2146
2147	static int i2c_quirk_error(struct i2c_adapter adap, struct* i2c_msg msg, char* *err_msg)
2148	{
2149	dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
2150	err_msg, msg->addr, msg->len,
2151	str_read_write(msg->flags & I2C_M_RD));
2152	return -EOPNOTSUPP;
2153	}
2154
2155	static int i2c_check_for_quirks(struct i2c_adapter adap, struct* i2c_msg msgs, int* num)
2156	{
2157	const struct i2c_adapter_quirks *q = adap->quirks;
2158	int max_num = q->max_num_msgs, i;
2159	bool do_len_check = true;
2160
2161	if (q->flags & I2C_AQ_COMB) {
2162	max_num = `2`;
2163
2164	/ special checks for combined messages /
2165	if (num == `2`) {
2166	if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[`0`].flags & I2C_M_RD)
2167	return i2c_quirk_error(adap, msg: &msgs[`0`], err_msg: "1st comb msg must be write");
2168
2169	if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[`1`].flags & I2C_M_RD))
2170	return i2c_quirk_error(adap, msg: &msgs[`1`], err_msg: "2nd comb msg must be read");
2171
2172	if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[`0`].addr != msgs[`1`].addr)
2173	return i2c_quirk_error(adap, msg: &msgs[`0`], err_msg: "comb msg only to same addr");
2174
2175	if (i2c_quirk_exceeded(msgs[`0`].len, q->max_comb_1st_msg_len))
2176	return i2c_quirk_error(adap, msg: &msgs[`0`], err_msg: "msg too long");
2177
2178	if (i2c_quirk_exceeded(msgs[`1`].len, q->max_comb_2nd_msg_len))
2179	return i2c_quirk_error(adap, msg: &msgs[`1`], err_msg: "msg too long");
2180
2181	do_len_check = false;
2182	}
2183	}
2184
2185	if (i2c_quirk_exceeded(num, max_num))
2186	return i2c_quirk_error(adap, msg: &msgs[`0`], err_msg: "too many messages");
2187
2188	for (i = `0`; i < num; i++) {
2189	u16 len = msgs[i].len;
2190
2191	if (msgs[i].flags & I2C_M_RD) {
2192	if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
2193	return i2c_quirk_error(adap, msg: &msgs[i], err_msg: "msg too long");
2194
2195	if (q->flags & I2C_AQ_NO_ZERO_LEN_READ && len == `0`)
2196	return i2c_quirk_error(adap, msg: &msgs[i], err_msg: "no zero length");
2197	} else {
2198	if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
2199	return i2c_quirk_error(adap, msg: &msgs[i], err_msg: "msg too long");
2200
2201	if (q->flags & I2C_AQ_NO_ZERO_LEN_WRITE && len == `0`)
2202	return i2c_quirk_error(adap, msg: &msgs[i], err_msg: "no zero length");
2203	}
2204	}
2205
2206	return `0`;
2207	}
2208
2209	/**
2210	* __i2c_transfer - unlocked flavor of i2c_transfer
2211	* @adap: Handle to I2C bus
2212	* @msgs: One or more messages to execute before STOP is issued to
2213	* terminate the operation; each message begins with a START.
2214	* @num: Number of messages to be executed.
2215	*
2216	* Returns negative errno, else the number of messages executed.
2217	*
2218	* Adapter lock must be held when calling this function. No debug logging
2219	* takes place.
2220	*/
2221	int __i2c_transfer(struct i2c_adapter adap, struct* i2c_msg msgs, int* num)
2222	{
2223	unsigned long orig_jiffies;
2224	int ret, try;
2225
2226	if (!adap->algo->master_xfer) {
2227	dev_dbg(&adap->dev, "I2C level transfers not supported\n");
2228	return -EOPNOTSUPP;
2229	}
2230
2231	if (WARN_ON(!msgs \|\| num < `1`))
2232	return -EINVAL;
2233
2234	ret = __i2c_check_suspended(adap);
2235	if (ret)
2236	return ret;
2237
2238	if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
2239	return -EOPNOTSUPP;
2240
2241	/*
2242	* i2c_trace_msg_key gets enabled when tracepoint i2c_transfer gets
2243	* enabled. This is an efficient way of keeping the for-loop from
2244	* being executed when not needed.
2245	*/
2246	if (static_branch_unlikely(&i2c_trace_msg_key)) {
2247	int i;
2248	for (i = `0`; i < num; i++)
2249	if (msgs[i].flags & I2C_M_RD)
2250	trace_i2c_read(adap, msg: &msgs[i], num: i);
2251	else
2252	trace_i2c_write(adap, msg: &msgs[i], num: i);
2253	}
2254
2255	/ Retry automatically on arbitration loss /
2256	orig_jiffies = jiffies;
2257	for (ret = `0`, try = `0`; try <= adap->retries; try++) {
2258	if (i2c_in_atomic_xfer_mode() && adap->algo->master_xfer_atomic)
2259	ret = adap->algo->master_xfer_atomic(adap, msgs, num);
2260	else
2261	ret = adap->algo->master_xfer(adap, msgs, num);
2262
2263	if (ret != -EAGAIN)
2264	break;
2265	if (time_after(jiffies, orig_jiffies + adap->timeout))
2266	break;
2267	}
2268
2269	if (static_branch_unlikely(&i2c_trace_msg_key)) {
2270	int i;
2271	for (i = `0`; i < ret; i++)
2272	if (msgs[i].flags & I2C_M_RD)
2273	trace_i2c_reply(adap, msg: &msgs[i], num: i);
2274	trace_i2c_result(adap, num, ret);
2275	}
2276
2277	return ret;
2278	}
2279	EXPORT_SYMBOL(__i2c_transfer);
2280
2281	/**
2282	* i2c_transfer - execute a single or combined I2C message
2283	* @adap: Handle to I2C bus
2284	* @msgs: One or more messages to execute before STOP is issued to
2285	* terminate the operation; each message begins with a START.
2286	* @num: Number of messages to be executed.
2287	*
2288	* Returns negative errno, else the number of messages executed.
2289	*
2290	* Note that there is no requirement that each message be sent to
2291	* the same slave address, although that is the most common model.
2292	*/
2293	int i2c_transfer(struct i2c_adapter adap, struct* i2c_msg msgs, int* num)
2294	{
2295	int ret;
2296
2297	/ REVISIT the fault reporting model here is weak:*
2298	*
2299	* - When we get an error after receiving N bytes from a slave,
2300	* there is no way to report "N".
2301	*
2302	* - When we get a NAK after transmitting N bytes to a slave,
2303	* there is no way to report "N" ... or to let the master
2304	* continue executing the rest of this combined message, if
2305	* that's the appropriate response.
2306	*
2307	* - When for example "num" is two and we successfully complete
2308	* the first message but get an error part way through the
2309	* second, it's unclear whether that should be reported as
2310	* one (discarding status on the second message) or errno
2311	* (discarding status on the first one).
2312	*/
2313	ret = __i2c_lock_bus_helper(adap);
2314	if (ret)
2315	return ret;
2316
2317	ret = __i2c_transfer(adap, msgs, num);
2318	i2c_unlock_bus(adapter: adap, I2C_LOCK_SEGMENT);
2319
2320	return ret;
2321	}
2322	EXPORT_SYMBOL(i2c_transfer);
2323
2324	/**
2325	* i2c_transfer_buffer_flags - issue a single I2C message transferring data
2326	* to/from a buffer
2327	* @client: Handle to slave device
2328	* @buf: Where the data is stored
2329	* @count: How many bytes to transfer, must be less than 64k since msg.len is u16
2330	* @flags: The flags to be used for the message, e.g. I2C_M_RD for reads
2331	*
2332	* Returns negative errno, or else the number of bytes transferred.
2333	*/
2334	int i2c_transfer_buffer_flags(const struct i2c_client client, char* *buf,
2335	int count, u16 flags)
2336	{
2337	int ret;
2338	struct i2c_msg msg = {
2339	.addr = client->addr,
2340	.flags = flags \| (client->flags & I2C_M_TEN),
2341	.len = count,
2342	.buf = buf,
2343	};
2344
2345	ret = i2c_transfer(client->adapter, &msg, `1`);
2346
2347	/*
2348	* If everything went ok (i.e. 1 msg transferred), return #bytes
2349	* transferred, else error code.
2350	*/
2351	return (ret == `1`) ? count : ret;
2352	}
2353	EXPORT_SYMBOL(i2c_transfer_buffer_flags);
2354
2355	/**
2356	* i2c_get_device_id - get manufacturer, part id and die revision of a device
2357	* @client: The device to query
2358	* @id: The queried information
2359	*
2360	* Returns negative errno on error, zero on success.
2361	*/
2362	int i2c_get_device_id(const struct i2c_client *client,
2363	struct i2c_device_identity *id)
2364	{
2365	struct i2c_adapter *adap = client->adapter;
2366	union i2c_smbus_data raw_id;
2367	int ret;
2368
2369	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
2370	return -EOPNOTSUPP;
2371
2372	raw_id.block[`0`] = `3`;
2373	ret = i2c_smbus_xfer(adapter: adap, I2C_ADDR_DEVICE_ID, flags: `0`,
2374	I2C_SMBUS_READ, command: client->addr << `1`,
2375	I2C_SMBUS_I2C_BLOCK_DATA, data: &raw_id);
2376	if (ret)
2377	return ret;
2378
2379	id->manufacturer_id = (raw_id.block[`1`] << `4`) \| (raw_id.block[`2`] >> `4`);
2380	id->part_id = ((raw_id.block[`2`] & `0xf`) << `5`) \| (raw_id.block[`3`] >> `3`);
2381	id->die_revision = raw_id.block[`3`] & `0x7`;
2382	return `0`;
2383	}
2384	EXPORT_SYMBOL_GPL(i2c_get_device_id);
2385
2386	/**
2387	* i2c_client_get_device_id - get the driver match table entry of a device
2388	* @client: the device to query. The device must be bound to a driver
2389	*
2390	* Returns a pointer to the matching entry if found, NULL otherwise.
2391	*/
2392	const struct i2c_device_id i2c_client_get_device_id(const* struct i2c_client *client)
2393	{
2394	const struct i2c_driver *drv = to_i2c_driver(client->dev.driver);
2395
2396	return i2c_match_id(drv->id_table, client);
2397	}
2398	EXPORT_SYMBOL_GPL(i2c_client_get_device_id);
2399
2400	/ ----------------------------------------------------*
2401	* the i2c address scanning function
2402	* Will not work for 10-bit addresses!
2403	* ----------------------------------------------------
2404	*/
2405
2406	/*
2407	* Legacy default probe function, mostly relevant for SMBus. The default
2408	* probe method is a quick write, but it is known to corrupt the 24RF08
2409	* EEPROMs due to a state machine bug, and could also irreversibly
2410	* write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
2411	* we use a short byte read instead. Also, some bus drivers don't implement
2412	* quick write, so we fallback to a byte read in that case too.
2413	* On x86, there is another special case for FSC hardware monitoring chips,
2414	* which want regular byte reads (address 0x73.) Fortunately, these are the
2415	* only known chips using this I2C address on PC hardware.
2416	* Returns 1 if probe succeeded, 0 if not.
2417	*/
2418	static int i2c_default_probe(struct i2c_adapter adap, unsigned* short addr)
2419	{
2420	int err;
2421	union i2c_smbus_data dummy;
2422
2423	#ifdef CONFIG_X86
2424	if (addr == `0x73` && (adap->class & I2C_CLASS_HWMON)
2425	&& i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
2426	err = i2c_smbus_xfer(adapter: adap, addr, flags: `0`, I2C_SMBUS_READ, command: `0`,
2427	I2C_SMBUS_BYTE_DATA, data: &dummy);
2428	else
2429	#endif
2430	if (!((addr & ~`0x07`) == `0x30` \|\| (addr & ~`0x0f`) == `0x50`)
2431	&& i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
2432	err = i2c_smbus_xfer(adapter: adap, addr, flags: `0`, I2C_SMBUS_WRITE, command: `0`,
2433	I2C_SMBUS_QUICK, NULL);
2434	else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
2435	err = i2c_smbus_xfer(adapter: adap, addr, flags: `0`, I2C_SMBUS_READ, command: `0`,
2436	I2C_SMBUS_BYTE, data: &dummy);
2437	else {
2438	dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
2439	addr);
2440	err = -EOPNOTSUPP;
2441	}
2442
2443	return err >= `0`;
2444	}
2445
2446	static int i2c_detect_address(struct i2c_client *temp_client,
2447	struct i2c_driver *driver)
2448	{
2449	struct i2c_board_info info;
2450	struct i2c_adapter *adapter = temp_client->adapter;
2451	int addr = temp_client->addr;
2452	int err;
2453
2454	/ Make sure the address is valid /
2455	err = i2c_check_7bit_addr_validity_strict(addr);
2456	if (err) {
2457	dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
2458	addr);
2459	return err;
2460	}
2461
2462	/ Skip if already in use (7 bit, no need to encode flags) /
2463	if (i2c_check_addr_busy(adapter, addr))
2464	return `0`;
2465
2466	/ Make sure there is something at this address /
2467	if (!i2c_default_probe(adap: adapter, addr))
2468	return `0`;
2469
2470	/ Finally call the custom detection function /
2471	memset(s: &info, c: `0`, n: sizeof(struct i2c_board_info));
2472	info.addr = addr;
2473	err = driver->detect(temp_client, &info);
2474	if (err) {
2475	/ -ENODEV is returned if the detection fails. We catch it*
2476	here as this isn't an error. /*
2477	return err == -ENODEV ? `0` : err;
2478	}
2479
2480	/ Consistency check /
2481	if (info.type[`0`] == `'\0'`) {
2482	dev_err(&adapter->dev,
2483	"%s detection function provided no name for 0x%x\n",
2484	driver->driver.name, addr);
2485	} else {
2486	struct i2c_client *client;
2487
2488	/ Detection succeeded, instantiate the device /
2489	if (adapter->class & I2C_CLASS_DEPRECATED)
2490	dev_warn(&adapter->dev,
2491	"This adapter will soon drop class based instantiation of devices. "
2492	"Please make sure client 0x%02x gets instantiated by other means. "
2493	"Check 'Documentation/i2c/instantiating-devices.rst' for details.\n",
2494	info.addr);
2495
2496	dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
2497	info.type, info.addr);
2498	client = i2c_new_client_device(adapter, &info);
2499	if (!IS_ERR(ptr: client))
2500	list_add_tail(new: &client->detected, head: &driver->clients);
2501	else
2502	dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
2503	info.type, info.addr);
2504	}
2505	return `0`;
2506	}
2507
2508	static int i2c_detect(struct i2c_adapter adapter, struct* i2c_driver *driver)
2509	{
2510	const unsigned short *address_list;
2511	struct i2c_client *temp_client;
2512	int i, err = `0`;
2513
2514	address_list = driver->address_list;
2515	if (!driver->detect \|\| !address_list)
2516	return `0`;
2517
2518	/ Warn that the adapter lost class based instantiation /
2519	if (adapter->class == I2C_CLASS_DEPRECATED) {
2520	dev_dbg(&adapter->dev,
2521	"This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. "
2522	"If you need it, check 'Documentation/i2c/instantiating-devices.rst' for alternatives.\n",
2523	driver->driver.name);
2524	return `0`;
2525	}
2526
2527	/ Stop here if the classes do not match /
2528	if (!(adapter->class & driver->class))
2529	return `0`;
2530
2531	/ Set up a temporary client to help detect callback /
2532	temp_client = kzalloc(sizeof(*temp_client), GFP_KERNEL);
2533	if (!temp_client)
2534	return -ENOMEM;
2535
2536	temp_client->adapter = adapter;
2537
2538	for (i = `0`; address_list[i] != I2C_CLIENT_END; i += `1`) {
2539	dev_dbg(&adapter->dev,
2540	"found normal entry for adapter %d, addr 0x%02x\n",
2541	i2c_adapter_id(adapter), address_list[i]);
2542	temp_client->addr = address_list[i];
2543	err = i2c_detect_address(temp_client, driver);
2544	if (unlikely(err))
2545	break;
2546	}
2547
2548	kfree(objp: temp_client);
2549
2550	return err;
2551	}
2552
2553	int i2c_probe_func_quick_read(struct i2c_adapter adap, unsigned* short addr)
2554	{
2555	return i2c_smbus_xfer(adapter: adap, addr, flags: `0`, I2C_SMBUS_READ, command: `0`,
2556	I2C_SMBUS_QUICK, NULL) >= `0`;
2557	}
2558	EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
2559
2560	struct i2c_client *
2561	i2c_new_scanned_device(struct i2c_adapter *adap,
2562	struct i2c_board_info *info,
2563	unsigned short const *addr_list,
2564	int (probe)(struct* i2c_adapter adap, unsigned* short addr))
2565	{
2566	int i;
2567
2568	if (!probe)
2569	probe = i2c_default_probe;
2570
2571	for (i = `0`; addr_list[i] != I2C_CLIENT_END; i++) {
2572	/ Check address validity /
2573	if (i2c_check_7bit_addr_validity_strict(addr: addr_list[i]) < `0`) {
2574	dev_warn(&adap->dev, "Invalid 7-bit address 0x%02x\n",
2575	addr_list[i]);
2576	continue;
2577	}
2578
2579	/ Check address availability (7 bit, no need to encode flags) /
2580	if (i2c_check_addr_busy(adapter: adap, addr: addr_list[i])) {
2581	dev_dbg(&adap->dev,
2582	"Address 0x%02x already in use, not probing\n",
2583	addr_list[i]);
2584	continue;
2585	}
2586
2587	/ Test address responsiveness /
2588	if (probe(adap, addr_list[i]))
2589	break;
2590	}
2591
2592	if (addr_list[i] == I2C_CLIENT_END) {
2593	dev_dbg(&adap->dev, "Probing failed, no device found\n");
2594	return ERR_PTR(error: -ENODEV);
2595	}
2596
2597	info->addr = addr_list[i];
2598	return i2c_new_client_device(adap, info);
2599	}
2600	EXPORT_SYMBOL_GPL(i2c_new_scanned_device);
2601
2602	struct i2c_adapter i2c_get_adapter(int* nr)
2603	{
2604	struct i2c_adapter *adapter;
2605
2606	mutex_lock(lock: &core_lock);
2607	adapter = idr_find(&i2c_adapter_idr, id: nr);
2608	if (!adapter)
2609	goto exit;
2610
2611	if (try_module_get(module: adapter->owner))
2612	get_device(dev: &adapter->dev);
2613	else
2614	adapter = NULL;
2615
2616	exit:
2617	mutex_unlock(lock: &core_lock);
2618	return adapter;
2619	}
2620	EXPORT_SYMBOL(i2c_get_adapter);
2621
2622	void i2c_put_adapter(struct i2c_adapter *adap)
2623	{
2624	if (!adap)
2625	return;
2626
2627	module_put(module: adap->owner);
2628	/ Should be last, otherwise we risk use-after-free with 'adap' /
2629	put_device(dev: &adap->dev);
2630	}
2631	EXPORT_SYMBOL(i2c_put_adapter);
2632
2633	/**
2634	* i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg
2635	* @msg: the message to be checked
2636	* @threshold: the minimum number of bytes for which using DMA makes sense.
2637	* Should at least be 1.
2638	*
2639	* Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.
2640	* Or a valid pointer to be used with DMA. After use, release it by
2641	* calling i2c_put_dma_safe_msg_buf().
2642	*
2643	* This function must only be called from process context!
2644	*/
2645	u8 i2c_get_dma_safe_msg_buf(struct* i2c_msg msg, unsigned* int threshold)
2646	{
2647	/ also skip 0-length msgs for bogus thresholds of 0 /
2648	if (!threshold)
2649	pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n",
2650	msg->addr);
2651	if (msg->len < threshold \|\| msg->len == `0`)
2652	return NULL;
2653
2654	if (msg->flags & I2C_M_DMA_SAFE)
2655	return msg->buf;
2656
2657	pr_debug("using bounce buffer for addr=0x%02x, len=%d\n",
2658	msg->addr, msg->len);
2659
2660	if (msg->flags & I2C_M_RD)
2661	return kzalloc(msg->len, GFP_KERNEL);
2662	else
2663	return kmemdup(msg->buf, msg->len, GFP_KERNEL);
2664	}
2665	EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf);
2666
2667	/**
2668	* i2c_put_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg
2669	* @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL.
2670	* @msg: the message which the buffer corresponds to
2671	* @xferred: bool saying if the message was transferred
2672	*/
2673	void i2c_put_dma_safe_msg_buf(u8 buf, struct* i2c_msg *msg, bool xferred)
2674	{
2675	if (!buf \|\| buf == msg->buf)
2676	return;
2677
2678	if (xferred && msg->flags & I2C_M_RD)
2679	memcpy(to: msg->buf, from: buf, len: msg->len);
2680
2681	kfree(objp: buf);
2682	}
2683	EXPORT_SYMBOL_GPL(i2c_put_dma_safe_msg_buf);
2684
2685	MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2686	MODULE_DESCRIPTION("I2C-Bus main module");
2687	MODULE_LICENSE("GPL");
2688

Browse the source code of Linux/drivers/i2c/i2c-core-base.c