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 */
__serial_port_busy(struct uart_port * port)24 static 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
serial_port_runtime_resume(struct device * dev)30 static 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(port, &flags);
43 if (!port_dev->tx_enabled)
44 goto unlock;
45 if (__serial_port_busy(port))
46 port->ops->start_tx(port);
47
48 unlock:
49 uart_port_unlock_irqrestore(port, flags);
50
51 out:
52 pm_runtime_mark_last_busy(dev);
53
54 return 0;
55 }
56
serial_port_runtime_suspend(struct device * dev)57 static 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(port, &flags);
75 if (!port_dev->tx_enabled) {
76 uart_port_unlock_irqrestore(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(port, flags);
84
85 if (busy)
86 pm_runtime_mark_last_busy(dev);
87
88 return busy ? -EBUSY : 0;
89 }
90
serial_base_port_set_tx(struct uart_port * port,struct serial_port_device * port_dev,bool enabled)91 static 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(port, &flags);
98 port_dev->tx_enabled = enabled;
99 uart_port_unlock_irqrestore(port, flags);
100 }
101
serial_base_port_startup(struct uart_port * port)102 void 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, true);
107 }
108
serial_base_port_shutdown(struct uart_port * port)109 void 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, false);
114 }
115
116 static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm,
117 serial_port_runtime_suspend,
118 serial_port_runtime_resume, NULL);
119
serial_port_probe(struct device * dev)120 static 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
serial_port_remove(struct device * dev)129 static 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 */
uart_add_one_port(struct uart_driver * drv,struct uart_port * port)141 int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
142 {
143 return serial_ctrl_register_port(drv, port);
144 }
145 EXPORT_SYMBOL(uart_add_one_port);
146
uart_remove_one_port(struct uart_driver * drv,struct uart_port * port)147 void uart_remove_one_port(struct uart_driver *drv, struct uart_port *port)
148 {
149 serial_ctrl_unregister_port(drv, port);
150 }
151 EXPORT_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 * ->mapbase
177 * ->mapsize
178 * ->regshift (if @use_defaults is false)
179 * before calling this function. Alternatively the above mentioned fields
180 * may be zeroed, in such case the only ones, that have associated properties
181 * found, will be set to the respective values.
182 *
183 * If no error happened, the ->irq, ->mapbase, ->mapsize will be altered.
184 * The ->iotype is always altered.
185 *
186 * When @use_defaults is true and the respective property is not found
187 * the following values will be applied:
188 * ->regshift = 0
189 * In this case IRQ must be provided, otherwise an error will be returned.
190 *
191 * When @use_defaults is false and the respective property is found
192 * the following values will be validated:
193 * - reg-io-width (->iotype)
194 * - reg-offset (->mapsize against ->mapbase)
195 *
196 * Returns: 0 on success or negative errno on failure
197 */
__uart_read_properties(struct uart_port * port,bool use_defaults)198 static int __uart_read_properties(struct uart_port *port, bool use_defaults)
199 {
200 struct device *dev = port->dev;
201 u32 value;
202 int ret;
203
204 /* Read optional UART functional clock frequency */
205 device_property_read_u32(dev, "clock-frequency", &port->uartclk);
206
207 /* Read the registers alignment (default: 8-bit) */
208 ret = device_property_read_u32(dev, "reg-shift", &value);
209 if (ret)
210 port->regshift = use_defaults ? 0 : port->regshift;
211 else
212 port->regshift = value;
213
214 /* Read the registers I/O access type (default: MMIO 8-bit) */
215 ret = device_property_read_u32(dev, "reg-io-width", &value);
216 if (ret) {
217 port->iotype = UPIO_MEM;
218 } else {
219 switch (value) {
220 case 1:
221 port->iotype = UPIO_MEM;
222 break;
223 case 2:
224 port->iotype = UPIO_MEM16;
225 break;
226 case 4:
227 port->iotype = device_is_big_endian(dev) ? UPIO_MEM32BE : UPIO_MEM32;
228 break;
229 default:
230 if (!use_defaults) {
231 dev_err(dev, "Unsupported reg-io-width (%u)\n", value);
232 return -EINVAL;
233 }
234 port->iotype = UPIO_UNKNOWN;
235 break;
236 }
237 }
238
239 /* Read the address mapping base offset (default: no offset) */
240 ret = device_property_read_u32(dev, "reg-offset", &value);
241 if (ret)
242 value = 0;
243
244 /* Check for shifted address mapping overflow */
245 if (!use_defaults && port->mapsize < value) {
246 dev_err(dev, "reg-offset %u exceeds region size %pa\n", value, &port->mapsize);
247 return -EINVAL;
248 }
249
250 port->mapbase += value;
251 port->mapsize -= value;
252
253 /* Read optional FIFO size */
254 device_property_read_u32(dev, "fifo-size", &port->fifosize);
255
256 if (device_property_read_bool(dev, "no-loopback-test"))
257 port->flags |= UPF_SKIP_TEST;
258
259 /* Get index of serial line, if found in DT aliases */
260 ret = of_alias_get_id(dev_of_node(dev), "serial");
261 if (ret >= 0)
262 port->line = ret;
263
264 if (dev_is_platform(dev))
265 ret = platform_get_irq(to_platform_device(dev), 0);
266 else if (dev_is_pnp(dev)) {
267 ret = pnp_irq(to_pnp_dev(dev), 0);
268 if (ret < 0)
269 ret = -ENXIO;
270 } else
271 ret = fwnode_irq_get(dev_fwnode(dev), 0);
272 if (ret == -EPROBE_DEFER)
273 return ret;
274 if (ret > 0)
275 port->irq = ret;
276 else if (use_defaults)
277 /* By default IRQ support is mandatory */
278 return ret;
279 else
280 port->irq = 0;
281
282 port->flags |= UPF_SHARE_IRQ;
283
284 return 0;
285 }
286
uart_read_port_properties(struct uart_port * port)287 int uart_read_port_properties(struct uart_port *port)
288 {
289 return __uart_read_properties(port, true);
290 }
291 EXPORT_SYMBOL_GPL(uart_read_port_properties);
292
uart_read_and_validate_port_properties(struct uart_port * port)293 int uart_read_and_validate_port_properties(struct uart_port *port)
294 {
295 return __uart_read_properties(port, false);
296 }
297 EXPORT_SYMBOL_GPL(uart_read_and_validate_port_properties);
298
299 static struct device_driver serial_port_driver = {
300 .name = "port",
301 .suppress_bind_attrs = true,
302 .probe = serial_port_probe,
303 .remove = serial_port_remove,
304 .pm = pm_ptr(&serial_port_pm),
305 };
306
serial_base_port_init(void)307 int serial_base_port_init(void)
308 {
309 return serial_base_driver_register(&serial_port_driver);
310 }
311
serial_base_port_exit(void)312 void serial_base_port_exit(void)
313 {
314 serial_base_driver_unregister(&serial_port_driver);
315 }
316
317 MODULE_AUTHOR("Tony Lindgren <tony@atomide.com>");
318 MODULE_DESCRIPTION("Serial controller port driver");
319 MODULE_LICENSE("GPL");
320