1// SPDX-License-Identifier: GPL-2.0
2/*
3 * PCIe Native PME support
4 *
5 * Copyright (C) 2007 - 2009 Intel Corp
6 * Copyright (C) 2007 - 2009 Shaohua Li <shaohua.li@intel.com>
7 * Copyright (C) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
8 */
9
10#define dev_fmt(fmt) "PME: " fmt
11
12#include <linux/bitfield.h>
13#include <linux/pci.h>
14#include <linux/kernel.h>
15#include <linux/errno.h>
16#include <linux/slab.h>
17#include <linux/init.h>
18#include <linux/interrupt.h>
19#include <linux/device.h>
20#include <linux/pm_runtime.h>
21
22#include "../pci.h"
23#include "portdrv.h"
24
25/*
26 * If this switch is set, MSI will not be used for PCIe PME signaling. This
27 * causes the PCIe port driver to use INTx interrupts only, but it turns out
28 * that using MSI for PCIe PME signaling doesn't play well with PCIe PME-based
29 * wake-up from system sleep states.
30 */
31bool pcie_pme_msi_disabled;
32
33static int __init pcie_pme_setup(char *str)
34{
35 if (!strncmp(str, "nomsi", 5))
36 pcie_pme_msi_disabled = true;
37
38 return 1;
39}
40__setup("pcie_pme=", pcie_pme_setup);
41
42struct pcie_pme_service_data {
43 spinlock_t lock;
44 struct pcie_device *srv;
45 struct work_struct work;
46 bool noirq; /* If set, keep the PME interrupt disabled. */
47};
48
49/**
50 * pcie_pme_interrupt_enable - Enable/disable PCIe PME interrupt generation.
51 * @dev: PCIe root port or event collector.
52 * @enable: Enable or disable the interrupt.
53 */
54void pcie_pme_interrupt_enable(struct pci_dev *dev, bool enable)
55{
56 if (enable)
57 pcie_capability_set_word(dev, PCI_EXP_RTCTL,
58 PCI_EXP_RTCTL_PMEIE);
59 else
60 pcie_capability_clear_word(dev, PCI_EXP_RTCTL,
61 PCI_EXP_RTCTL_PMEIE);
62}
63
64/**
65 * pcie_pme_walk_bus - Scan a PCI bus for devices asserting PME#.
66 * @bus: PCI bus to scan.
67 *
68 * Scan given PCI bus and all buses under it for devices asserting PME#.
69 */
70static bool pcie_pme_walk_bus(struct pci_bus *bus)
71{
72 struct pci_dev *dev;
73 bool ret = false;
74
75 list_for_each_entry(dev, &bus->devices, bus_list) {
76 /* Skip PCIe devices in case we started from a root port. */
77 if (!pci_is_pcie(dev) && pci_check_pme_status(dev)) {
78 if (dev->pme_poll)
79 dev->pme_poll = false;
80
81 pci_wakeup_event(dev);
82 pm_request_resume(dev: &dev->dev);
83 ret = true;
84 }
85
86 if (dev->subordinate && pcie_pme_walk_bus(bus: dev->subordinate))
87 ret = true;
88 }
89
90 return ret;
91}
92
93/**
94 * pcie_pme_from_pci_bridge - Check if PCIe-PCI bridge generated a PME.
95 * @bus: Secondary bus of the bridge.
96 * @devfn: Device/function number to check.
97 *
98 * PME from PCI devices under a PCIe-PCI bridge may be converted to an in-band
99 * PCIe PME message. In such that case the bridge should use the Requester ID
100 * of device/function number 0 on its secondary bus.
101 */
102static bool pcie_pme_from_pci_bridge(struct pci_bus *bus, u8 devfn)
103{
104 struct pci_dev *dev;
105 bool found = false;
106
107 if (devfn)
108 return false;
109
110 dev = pci_dev_get(dev: bus->self);
111 if (!dev)
112 return false;
113
114 if (pci_is_pcie(dev) && pci_pcie_type(dev) == PCI_EXP_TYPE_PCI_BRIDGE) {
115 down_read(sem: &pci_bus_sem);
116 if (pcie_pme_walk_bus(bus))
117 found = true;
118 up_read(sem: &pci_bus_sem);
119 }
120
121 pci_dev_put(dev);
122 return found;
123}
124
125/**
126 * pcie_pme_handle_request - Find device that generated PME and handle it.
127 * @port: Root port or event collector that generated the PME interrupt.
128 * @req_id: PCIe Requester ID of the device that generated the PME.
129 */
130static void pcie_pme_handle_request(struct pci_dev *port, u16 req_id)
131{
132 u8 busnr = req_id >> 8, devfn = req_id & 0xff;
133 struct pci_bus *bus;
134 struct pci_dev *dev;
135 bool found = false;
136
137 /* First, check if the PME is from the root port itself. */
138 if (port->devfn == devfn && port->bus->number == busnr) {
139 if (port->pme_poll)
140 port->pme_poll = false;
141
142 if (pci_check_pme_status(dev: port)) {
143 pm_request_resume(dev: &port->dev);
144 found = true;
145 } else {
146 /*
147 * Apparently, the root port generated the PME on behalf
148 * of a non-PCIe device downstream. If this is done by
149 * a root port, the Requester ID field in its status
150 * register may contain either the root port's, or the
151 * source device's information (PCI Express Base
152 * Specification, Rev. 2.0, Section 6.1.9).
153 */
154 down_read(sem: &pci_bus_sem);
155 found = pcie_pme_walk_bus(bus: port->subordinate);
156 up_read(sem: &pci_bus_sem);
157 }
158 goto out;
159 }
160
161 /* Second, find the bus the source device is on. */
162 bus = pci_find_bus(domain: pci_domain_nr(bus: port->bus), busnr);
163 if (!bus)
164 goto out;
165
166 /* Next, check if the PME is from a PCIe-PCI bridge. */
167 found = pcie_pme_from_pci_bridge(bus, devfn);
168 if (found)
169 goto out;
170
171 /* Finally, try to find the PME source on the bus. */
172 down_read(sem: &pci_bus_sem);
173 list_for_each_entry(dev, &bus->devices, bus_list) {
174 pci_dev_get(dev);
175 if (dev->devfn == devfn) {
176 found = true;
177 break;
178 }
179 pci_dev_put(dev);
180 }
181 up_read(sem: &pci_bus_sem);
182
183 if (found) {
184 /* The device is there, but we have to check its PME status. */
185 found = pci_check_pme_status(dev);
186 if (found) {
187 if (dev->pme_poll)
188 dev->pme_poll = false;
189
190 pci_wakeup_event(dev);
191 pm_request_resume(dev: &dev->dev);
192 }
193 pci_dev_put(dev);
194 } else if (devfn) {
195 /*
196 * The device is not there, but we can still try to recover by
197 * assuming that the PME was reported by a PCIe-PCI bridge that
198 * used devfn different from zero.
199 */
200 pci_info(port, "interrupt generated for non-existent device %02x:%02x.%d\n",
201 busnr, PCI_SLOT(devfn), PCI_FUNC(devfn));
202 found = pcie_pme_from_pci_bridge(bus, devfn: 0);
203 }
204
205 out:
206 if (!found)
207 pci_info(port, "Spurious native interrupt!\n");
208}
209
210/**
211 * pcie_pme_work_fn - Work handler for PCIe PME interrupt.
212 * @work: Work structure giving access to service data.
213 */
214static void pcie_pme_work_fn(struct work_struct *work)
215{
216 struct pcie_pme_service_data *data =
217 container_of(work, struct pcie_pme_service_data, work);
218 struct pci_dev *port = data->srv->port;
219 u32 rtsta;
220
221 spin_lock_irq(lock: &data->lock);
222
223 for (;;) {
224 if (data->noirq)
225 break;
226
227 pcie_capability_read_dword(dev: port, PCI_EXP_RTSTA, val: &rtsta);
228 if (PCI_POSSIBLE_ERROR(rtsta))
229 break;
230
231 if (rtsta & PCI_EXP_RTSTA_PME) {
232 /*
233 * Clear PME status of the port. If there are other
234 * pending PMEs, the status will be set again.
235 */
236 pcie_clear_root_pme_status(dev: port);
237
238 spin_unlock_irq(lock: &data->lock);
239 pcie_pme_handle_request(port,
240 FIELD_GET(PCI_EXP_RTSTA_PME_RQ_ID, rtsta));
241 spin_lock_irq(lock: &data->lock);
242
243 continue;
244 }
245
246 /* No need to loop if there are no more PMEs pending. */
247 if (!(rtsta & PCI_EXP_RTSTA_PENDING))
248 break;
249
250 spin_unlock_irq(lock: &data->lock);
251 cpu_relax();
252 spin_lock_irq(lock: &data->lock);
253 }
254
255 if (!data->noirq)
256 pcie_pme_interrupt_enable(dev: port, enable: true);
257
258 spin_unlock_irq(lock: &data->lock);
259}
260
261/**
262 * pcie_pme_irq - Interrupt handler for PCIe root port PME interrupt.
263 * @irq: Interrupt vector.
264 * @context: Interrupt context pointer.
265 */
266static irqreturn_t pcie_pme_irq(int irq, void *context)
267{
268 struct pci_dev *port;
269 struct pcie_pme_service_data *data;
270 u32 rtsta;
271 unsigned long flags;
272
273 port = ((struct pcie_device *)context)->port;
274 data = get_service_data(dev: (struct pcie_device *)context);
275
276 spin_lock_irqsave(&data->lock, flags);
277 pcie_capability_read_dword(dev: port, PCI_EXP_RTSTA, val: &rtsta);
278
279 if (PCI_POSSIBLE_ERROR(rtsta) || !(rtsta & PCI_EXP_RTSTA_PME)) {
280 spin_unlock_irqrestore(lock: &data->lock, flags);
281 return IRQ_NONE;
282 }
283
284 pcie_pme_interrupt_enable(dev: port, enable: false);
285 spin_unlock_irqrestore(lock: &data->lock, flags);
286
287 /* We don't use pm_wq, because it's freezable. */
288 schedule_work(work: &data->work);
289
290 return IRQ_HANDLED;
291}
292
293/**
294 * pcie_pme_can_wakeup - Set the wakeup capability flag.
295 * @dev: PCI device to handle.
296 * @ign: Ignored.
297 */
298static int pcie_pme_can_wakeup(struct pci_dev *dev, void *ign)
299{
300 device_set_wakeup_capable(dev: &dev->dev, capable: true);
301 return 0;
302}
303
304/**
305 * pcie_pme_mark_devices - Set the wakeup flag for devices below a port.
306 * @port: PCIe root port or event collector to handle.
307 *
308 * For each device below given root port, including the port itself (or for each
309 * root complex integrated endpoint if @port is a root complex event collector)
310 * set the flag indicating that it can signal run-time wake-up events.
311 */
312static void pcie_pme_mark_devices(struct pci_dev *port)
313{
314 pcie_pme_can_wakeup(dev: port, NULL);
315
316 if (pci_pcie_type(dev: port) == PCI_EXP_TYPE_RC_EC)
317 pcie_walk_rcec(rcec: port, cb: pcie_pme_can_wakeup, NULL);
318 else if (port->subordinate)
319 pci_walk_bus(top: port->subordinate, cb: pcie_pme_can_wakeup, NULL);
320}
321
322/**
323 * pcie_pme_probe - Initialize PCIe PME service for given root port.
324 * @srv: PCIe service to initialize.
325 */
326static int pcie_pme_probe(struct pcie_device *srv)
327{
328 struct pci_dev *port = srv->port;
329 struct pcie_pme_service_data *data;
330 int type = pci_pcie_type(dev: port);
331 int ret;
332
333 /* Limit to Root Ports or Root Complex Event Collectors */
334 if (type != PCI_EXP_TYPE_RC_EC &&
335 type != PCI_EXP_TYPE_ROOT_PORT)
336 return -ENODEV;
337
338 data = kzalloc(sizeof(*data), GFP_KERNEL);
339 if (!data)
340 return -ENOMEM;
341
342 spin_lock_init(&data->lock);
343 INIT_WORK(&data->work, pcie_pme_work_fn);
344 data->srv = srv;
345 set_service_data(dev: srv, data);
346
347 pcie_pme_interrupt_enable(dev: port, enable: false);
348 pcie_clear_root_pme_status(dev: port);
349
350 ret = request_irq(irq: srv->irq, handler: pcie_pme_irq, IRQF_SHARED, name: "PCIe PME", dev: srv);
351 if (ret) {
352 kfree(objp: data);
353 return ret;
354 }
355
356 pci_info(port, "Signaling with IRQ %d\n", srv->irq);
357
358 pcie_pme_mark_devices(port);
359 pcie_pme_interrupt_enable(dev: port, enable: true);
360 return 0;
361}
362
363static bool pcie_pme_check_wakeup(struct pci_bus *bus)
364{
365 struct pci_dev *dev;
366
367 if (!bus)
368 return false;
369
370 list_for_each_entry(dev, &bus->devices, bus_list)
371 if (device_may_wakeup(dev: &dev->dev)
372 || pcie_pme_check_wakeup(bus: dev->subordinate))
373 return true;
374
375 return false;
376}
377
378static void pcie_pme_disable_interrupt(struct pci_dev *port,
379 struct pcie_pme_service_data *data)
380{
381 spin_lock_irq(lock: &data->lock);
382 pcie_pme_interrupt_enable(dev: port, enable: false);
383 pcie_clear_root_pme_status(dev: port);
384 data->noirq = true;
385 spin_unlock_irq(lock: &data->lock);
386}
387
388/**
389 * pcie_pme_suspend - Suspend PCIe PME service device.
390 * @srv: PCIe service device to suspend.
391 */
392static int pcie_pme_suspend(struct pcie_device *srv)
393{
394 struct pcie_pme_service_data *data = get_service_data(dev: srv);
395 struct pci_dev *port = srv->port;
396 bool wakeup;
397 int ret;
398
399 if (device_may_wakeup(dev: &port->dev)) {
400 wakeup = true;
401 } else {
402 down_read(sem: &pci_bus_sem);
403 wakeup = pcie_pme_check_wakeup(bus: port->subordinate);
404 up_read(sem: &pci_bus_sem);
405 }
406 if (wakeup) {
407 ret = enable_irq_wake(irq: srv->irq);
408 if (!ret)
409 return 0;
410 }
411
412 pcie_pme_disable_interrupt(port, data);
413
414 synchronize_irq(irq: srv->irq);
415
416 return 0;
417}
418
419/**
420 * pcie_pme_resume - Resume PCIe PME service device.
421 * @srv: PCIe service device to resume.
422 */
423static int pcie_pme_resume(struct pcie_device *srv)
424{
425 struct pcie_pme_service_data *data = get_service_data(dev: srv);
426
427 spin_lock_irq(lock: &data->lock);
428 if (data->noirq) {
429 struct pci_dev *port = srv->port;
430
431 pcie_clear_root_pme_status(dev: port);
432 pcie_pme_interrupt_enable(dev: port, enable: true);
433 data->noirq = false;
434 } else {
435 disable_irq_wake(irq: srv->irq);
436 }
437 spin_unlock_irq(lock: &data->lock);
438
439 return 0;
440}
441
442/**
443 * pcie_pme_remove - Prepare PCIe PME service device for removal.
444 * @srv: PCIe service device to remove.
445 */
446static void pcie_pme_remove(struct pcie_device *srv)
447{
448 struct pcie_pme_service_data *data = get_service_data(dev: srv);
449
450 pcie_pme_disable_interrupt(port: srv->port, data);
451 free_irq(srv->irq, srv);
452 cancel_work_sync(work: &data->work);
453 kfree(objp: data);
454}
455
456static struct pcie_port_service_driver pcie_pme_driver = {
457 .name = "pcie_pme",
458 .port_type = PCIE_ANY_PORT,
459 .service = PCIE_PORT_SERVICE_PME,
460
461 .probe = pcie_pme_probe,
462 .suspend = pcie_pme_suspend,
463 .resume = pcie_pme_resume,
464 .remove = pcie_pme_remove,
465};
466
467/**
468 * pcie_pme_init - Register the PCIe PME service driver.
469 */
470int __init pcie_pme_init(void)
471{
472 return pcie_port_service_register(new: &pcie_pme_driver);
473}
474