1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Serial core port device driver
4 *
5 * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
6 * Author: Tony Lindgren <tony@atomide.com>
7 */
8
9#include <linux/device.h>
10#include <linux/module.h>
11#include <linux/of.h>
12#include <linux/platform_device.h>
13#include <linux/pm_runtime.h>
14#include <linux/pnp.h>
15#include <linux/property.h>
16#include <linux/serial_core.h>
17#include <linux/spinlock.h>
18
19#include "serial_base.h"
20
21#define SERIAL_PORT_AUTOSUSPEND_DELAY_MS 500
22
23/* Only considers pending TX for now. Caller must take care of locking */
24static int __serial_port_busy(struct uart_port *port)
25{
26 return !uart_tx_stopped(port) &&
27 !kfifo_is_empty(&port->state->port.xmit_fifo);
28}
29
30static int serial_port_runtime_resume(struct device *dev)
31{
32 struct serial_port_device *port_dev = to_serial_base_port_device(dev);
33 struct uart_port *port;
34 unsigned long flags;
35
36 port = port_dev->port;
37
38 if (port->flags & UPF_DEAD)
39 goto out;
40
41 /* Flush any pending TX for the port */
42 uart_port_lock_irqsave(up: port, flags: &flags);
43 if (!port_dev->tx_enabled)
44 goto unlock;
45 if (__serial_port_busy(port))
46 port->ops->start_tx(port);
47
48unlock:
49 uart_port_unlock_irqrestore(up: port, flags);
50
51out:
52 pm_runtime_mark_last_busy(dev);
53
54 return 0;
55}
56
57static int serial_port_runtime_suspend(struct device *dev)
58{
59 struct serial_port_device *port_dev = to_serial_base_port_device(dev);
60 struct uart_port *port = port_dev->port;
61 unsigned long flags;
62 bool busy;
63
64 if (port->flags & UPF_DEAD)
65 return 0;
66
67 /*
68 * Nothing to do on pm_runtime_force_suspend(), see
69 * DEFINE_RUNTIME_DEV_PM_OPS.
70 */
71 if (!pm_runtime_enabled(dev))
72 return 0;
73
74 uart_port_lock_irqsave(up: port, flags: &flags);
75 if (!port_dev->tx_enabled) {
76 uart_port_unlock_irqrestore(up: port, flags);
77 return 0;
78 }
79
80 busy = __serial_port_busy(port);
81 if (busy)
82 port->ops->start_tx(port);
83 uart_port_unlock_irqrestore(up: port, flags);
84
85 if (busy)
86 pm_runtime_mark_last_busy(dev);
87
88 return busy ? -EBUSY : 0;
89}
90
91static void serial_base_port_set_tx(struct uart_port *port,
92 struct serial_port_device *port_dev,
93 bool enabled)
94{
95 unsigned long flags;
96
97 uart_port_lock_irqsave(up: port, flags: &flags);
98 port_dev->tx_enabled = enabled;
99 uart_port_unlock_irqrestore(up: port, flags);
100}
101
102void serial_base_port_startup(struct uart_port *port)
103{
104 struct serial_port_device *port_dev = port->port_dev;
105
106 serial_base_port_set_tx(port, port_dev, enabled: true);
107}
108
109void serial_base_port_shutdown(struct uart_port *port)
110{
111 struct serial_port_device *port_dev = port->port_dev;
112
113 serial_base_port_set_tx(port, port_dev, enabled: false);
114}
115
116static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm,
117 serial_port_runtime_suspend,
118 serial_port_runtime_resume, NULL);
119
120static int serial_port_probe(struct device *dev)
121{
122 pm_runtime_enable(dev);
123 pm_runtime_set_autosuspend_delay(dev, SERIAL_PORT_AUTOSUSPEND_DELAY_MS);
124 pm_runtime_use_autosuspend(dev);
125
126 return 0;
127}
128
129static int serial_port_remove(struct device *dev)
130{
131 pm_runtime_dont_use_autosuspend(dev);
132 pm_runtime_disable(dev);
133
134 return 0;
135}
136
137/*
138 * Serial core port device init functions. Note that the physical serial
139 * port device driver may not have completed probe at this point.
140 */
141int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
142{
143 return serial_ctrl_register_port(drv, port);
144}
145EXPORT_SYMBOL(uart_add_one_port);
146
147void uart_remove_one_port(struct uart_driver *drv, struct uart_port *port)
148{
149 serial_ctrl_unregister_port(drv, port);
150}
151EXPORT_SYMBOL(uart_remove_one_port);
152
153/**
154 * __uart_read_properties - read firmware properties of the given UART port
155 * @port: corresponding port
156 * @use_defaults: apply defaults (when %true) or validate the values (when %false)
157 *
158 * The following device properties are supported:
159 * - clock-frequency (optional)
160 * - fifo-size (optional)
161 * - no-loopback-test (optional)
162 * - reg-shift (defaults may apply)
163 * - reg-offset (value may be validated)
164 * - reg-io-width (defaults may apply or value may be validated)
165 * - interrupts (OF only)
166 * - serial [alias ID] (OF only)
167 *
168 * If the port->dev is of struct platform_device type the interrupt line
169 * will be retrieved via platform_get_irq() call against that device.
170 * Otherwise it will be assigned by fwnode_irq_get() call. In both cases
171 * the index 0 of the resource is used.
172 *
173 * The caller is responsible to initialize the following fields of the @port
174 * ->dev (must be valid)
175 * ->flags
176 * ->iobase
177 * ->mapbase
178 * ->mapsize
179 * ->regshift (if @use_defaults is false)
180 * before calling this function. Alternatively the above mentioned fields
181 * may be zeroed, in such case the only ones, that have associated properties
182 * found, will be set to the respective values.
183 *
184 * If no error happened, the ->irq, ->mapbase, ->mapsize will be altered.
185 * The ->iotype is always altered.
186 *
187 * When @use_defaults is true and the respective property is not found
188 * the following values will be applied:
189 * ->regshift = 0
190 * In this case IRQ must be provided, otherwise an error will be returned.
191 *
192 * When @use_defaults is false and the respective property is found
193 * the following values will be validated:
194 * - reg-io-width (->iotype)
195 * - reg-offset (->mapsize against ->mapbase)
196 *
197 * Returns: 0 on success or negative errno on failure
198 */
199static int __uart_read_properties(struct uart_port *port, bool use_defaults)
200{
201 struct device *dev = port->dev;
202 u32 value;
203 int ret;
204
205 /* Read optional UART functional clock frequency */
206 device_property_read_u32(dev, propname: "clock-frequency", val: &port->uartclk);
207
208 /* Read the registers alignment (default: 8-bit) */
209 ret = device_property_read_u32(dev, propname: "reg-shift", val: &value);
210 if (ret)
211 port->regshift = use_defaults ? 0 : port->regshift;
212 else
213 port->regshift = value;
214
215 /* Read the registers I/O access type (default: MMIO 8-bit) */
216 ret = device_property_read_u32(dev, propname: "reg-io-width", val: &value);
217 if (ret) {
218 port->iotype = port->iobase ? UPIO_PORT : UPIO_MEM;
219 } else {
220 switch (value) {
221 case 1:
222 port->iotype = UPIO_MEM;
223 break;
224 case 2:
225 port->iotype = UPIO_MEM16;
226 break;
227 case 4:
228 port->iotype = device_is_big_endian(dev) ? UPIO_MEM32BE : UPIO_MEM32;
229 break;
230 default:
231 port->iotype = UPIO_UNKNOWN;
232 break;
233 }
234 }
235
236 if (!use_defaults && port->iotype == UPIO_UNKNOWN) {
237 dev_err(dev, "Unsupported reg-io-width (%u)\n", value);
238 return -EINVAL;
239 }
240
241 /* Read the address mapping base offset (default: no offset) */
242 ret = device_property_read_u32(dev, propname: "reg-offset", val: &value);
243 if (ret)
244 value = 0;
245
246 /* Check for shifted address mapping overflow */
247 if (!use_defaults && port->mapsize < value) {
248 dev_err(dev, "reg-offset %u exceeds region size %pa\n", value, &port->mapsize);
249 return -EINVAL;
250 }
251
252 port->mapbase += value;
253 port->mapsize -= value;
254
255 /* Read optional FIFO size */
256 device_property_read_u32(dev, propname: "fifo-size", val: &port->fifosize);
257
258 if (device_property_read_bool(dev, propname: "no-loopback-test"))
259 port->flags |= UPF_SKIP_TEST;
260
261 /* Get index of serial line, if found in DT aliases */
262 ret = of_alias_get_id(np: dev_of_node(dev), stem: "serial");
263 if (ret >= 0)
264 port->line = ret;
265
266 if (dev_is_platform(dev))
267 ret = platform_get_irq(to_platform_device(dev), 0);
268 else if (dev_is_pnp(dev)) {
269 ret = pnp_irq(to_pnp_dev(dev), bar: 0);
270 if (ret < 0)
271 ret = -ENXIO;
272 } else
273 ret = fwnode_irq_get(dev_fwnode(dev), index: 0);
274 if (ret == -EPROBE_DEFER)
275 return ret;
276 if (ret > 0)
277 port->irq = ret;
278 else if (use_defaults)
279 /* By default IRQ support is mandatory */
280 return ret;
281 else
282 port->irq = 0;
283
284 port->flags |= UPF_SHARE_IRQ;
285
286 return 0;
287}
288
289int uart_read_port_properties(struct uart_port *port)
290{
291 return __uart_read_properties(port, use_defaults: true);
292}
293EXPORT_SYMBOL_GPL(uart_read_port_properties);
294
295int uart_read_and_validate_port_properties(struct uart_port *port)
296{
297 return __uart_read_properties(port, use_defaults: false);
298}
299EXPORT_SYMBOL_GPL(uart_read_and_validate_port_properties);
300
301static struct device_driver serial_port_driver = {
302 .name = "port",
303 .suppress_bind_attrs = true,
304 .probe = serial_port_probe,
305 .remove = serial_port_remove,
306 .pm = pm_ptr(&serial_port_pm),
307};
308
309int serial_base_port_init(void)
310{
311 return serial_base_driver_register(driver: &serial_port_driver);
312}
313
314void serial_base_port_exit(void)
315{
316 serial_base_driver_unregister(driver: &serial_port_driver);
317}
318
319MODULE_AUTHOR("Tony Lindgren <tony@atomide.com>");
320MODULE_DESCRIPTION("Serial controller port driver");
321MODULE_LICENSE("GPL");
322