1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/completion.h>
4 #include <linux/delay.h>
5 #include <linux/leds.h>
6 #include <linux/module.h>
7 #include <linux/slab.h>
9 #include <uapi/linux/serial.h>
11 #define LEDTRIG_TTY_INTERVAL 50
13 struct ledtrig_tty_data {
14 struct led_classdev *led_cdev;
15 struct delayed_work dwork;
16 struct completion sysfs;
18 struct tty_struct *tty;
28 /* Indicates which state the LED should now display */
29 enum led_trigger_tty_state {
35 enum led_trigger_tty_modes {
44 static int ledtrig_tty_wait_for_completion(struct device *dev)
46 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
49 ret = wait_for_completion_timeout(&trigger_data->sysfs,
50 msecs_to_jiffies(LEDTRIG_TTY_INTERVAL * 20));
57 static ssize_t ttyname_show(struct device *dev,
58 struct device_attribute *attr, char *buf)
60 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
64 reinit_completion(&trigger_data->sysfs);
65 completion = ledtrig_tty_wait_for_completion(dev);
69 if (trigger_data->ttyname)
70 len = sprintf(buf, "%s\n", trigger_data->ttyname);
75 static ssize_t ttyname_store(struct device *dev,
76 struct device_attribute *attr, const char *buf,
79 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
84 if (size > 0 && buf[size - 1] == '\n')
88 ttyname = kmemdup_nul(buf, size, GFP_KERNEL);
95 reinit_completion(&trigger_data->sysfs);
96 completion = ledtrig_tty_wait_for_completion(dev);
100 kfree(trigger_data->ttyname);
101 tty_kref_put(trigger_data->tty);
102 trigger_data->tty = NULL;
104 trigger_data->ttyname = ttyname;
108 static DEVICE_ATTR_RW(ttyname);
110 static ssize_t ledtrig_tty_attr_show(struct device *dev, char *buf,
111 enum led_trigger_tty_modes attr)
113 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
118 state = trigger_data->mode_rx;
121 state = trigger_data->mode_tx;
123 case TRIGGER_TTY_CTS:
124 state = trigger_data->mode_cts;
126 case TRIGGER_TTY_DSR:
127 state = trigger_data->mode_dsr;
129 case TRIGGER_TTY_DCD:
130 state = trigger_data->mode_dcd;
132 case TRIGGER_TTY_RNG:
133 state = trigger_data->mode_rng;
137 return sysfs_emit(buf, "%u\n", state);
140 static ssize_t ledtrig_tty_attr_store(struct device *dev, const char *buf,
141 size_t size, enum led_trigger_tty_modes attr)
143 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
147 ret = kstrtobool(buf, &state);
153 trigger_data->mode_rx = state;
156 trigger_data->mode_tx = state;
158 case TRIGGER_TTY_CTS:
159 trigger_data->mode_cts = state;
161 case TRIGGER_TTY_DSR:
162 trigger_data->mode_dsr = state;
164 case TRIGGER_TTY_DCD:
165 trigger_data->mode_dcd = state;
167 case TRIGGER_TTY_RNG:
168 trigger_data->mode_rng = state;
175 #define DEFINE_TTY_TRIGGER(trigger_name, trigger) \
176 static ssize_t trigger_name##_show(struct device *dev, \
177 struct device_attribute *attr, char *buf) \
179 return ledtrig_tty_attr_show(dev, buf, trigger); \
181 static ssize_t trigger_name##_store(struct device *dev, \
182 struct device_attribute *attr, const char *buf, size_t size) \
184 return ledtrig_tty_attr_store(dev, buf, size, trigger); \
186 static DEVICE_ATTR_RW(trigger_name)
188 DEFINE_TTY_TRIGGER(rx, TRIGGER_TTY_RX);
189 DEFINE_TTY_TRIGGER(tx, TRIGGER_TTY_TX);
190 DEFINE_TTY_TRIGGER(cts, TRIGGER_TTY_CTS);
191 DEFINE_TTY_TRIGGER(dsr, TRIGGER_TTY_DSR);
192 DEFINE_TTY_TRIGGER(dcd, TRIGGER_TTY_DCD);
193 DEFINE_TTY_TRIGGER(rng, TRIGGER_TTY_RNG);
195 static void ledtrig_tty_work(struct work_struct *work)
197 struct ledtrig_tty_data *trigger_data =
198 container_of(work, struct ledtrig_tty_data, dwork.work);
199 enum led_trigger_tty_state state = TTY_LED_DISABLE;
200 unsigned long interval = LEDTRIG_TTY_INTERVAL;
205 if (!trigger_data->ttyname)
208 /* try to get the tty corresponding to $ttyname */
209 if (!trigger_data->tty) {
211 struct tty_struct *tty;
214 ret = tty_dev_name_to_number(trigger_data->ttyname, &devno);
217 * A device with this name might appear later, so keep
222 tty = tty_kopen_shared(devno);
223 if (IS_ERR(tty) || !tty)
224 /* What to do? retry or abort */
227 trigger_data->tty = tty;
230 status = tty_get_tiocm(trigger_data->tty);
232 if (trigger_data->mode_cts) {
233 if (status & TIOCM_CTS)
234 state = TTY_LED_ENABLE;
237 if (trigger_data->mode_dsr) {
238 if (status & TIOCM_DSR)
239 state = TTY_LED_ENABLE;
242 if (trigger_data->mode_dcd) {
243 if (status & TIOCM_CAR)
244 state = TTY_LED_ENABLE;
247 if (trigger_data->mode_rng) {
248 if (status & TIOCM_RNG)
249 state = TTY_LED_ENABLE;
254 * The evaluation of rx/tx must be done after the evaluation
255 * of TIOCM_*, because rx/tx has priority.
257 if (trigger_data->mode_rx || trigger_data->mode_tx) {
258 struct serial_icounter_struct icount;
260 ret = tty_get_icount(trigger_data->tty, &icount);
264 if (trigger_data->mode_tx && (icount.tx != trigger_data->tx)) {
265 trigger_data->tx = icount.tx;
266 invert = state == TTY_LED_ENABLE;
267 state = TTY_LED_BLINK;
270 if (trigger_data->mode_rx && (icount.rx != trigger_data->rx)) {
271 trigger_data->rx = icount.rx;
272 invert = state == TTY_LED_ENABLE;
273 state = TTY_LED_BLINK;
280 led_blink_set_oneshot(trigger_data->led_cdev, &interval,
284 led_set_brightness(trigger_data->led_cdev,
285 trigger_data->led_cdev->blink_brightness);
287 case TTY_LED_DISABLE:
290 led_set_brightness(trigger_data->led_cdev, LED_OFF);
294 complete_all(&trigger_data->sysfs);
295 schedule_delayed_work(&trigger_data->dwork,
296 msecs_to_jiffies(LEDTRIG_TTY_INTERVAL * 2));
299 static struct attribute *ledtrig_tty_attrs[] = {
300 &dev_attr_ttyname.attr,
309 ATTRIBUTE_GROUPS(ledtrig_tty);
311 static int ledtrig_tty_activate(struct led_classdev *led_cdev)
313 struct ledtrig_tty_data *trigger_data;
315 trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
319 /* Enable default rx/tx mode */
320 trigger_data->mode_rx = true;
321 trigger_data->mode_tx = true;
323 led_set_trigger_data(led_cdev, trigger_data);
325 INIT_DELAYED_WORK(&trigger_data->dwork, ledtrig_tty_work);
326 trigger_data->led_cdev = led_cdev;
327 init_completion(&trigger_data->sysfs);
329 schedule_delayed_work(&trigger_data->dwork, 0);
334 static void ledtrig_tty_deactivate(struct led_classdev *led_cdev)
336 struct ledtrig_tty_data *trigger_data = led_get_trigger_data(led_cdev);
338 cancel_delayed_work_sync(&trigger_data->dwork);
340 kfree(trigger_data->ttyname);
341 tty_kref_put(trigger_data->tty);
342 trigger_data->tty = NULL;
347 static struct led_trigger ledtrig_tty = {
349 .activate = ledtrig_tty_activate,
350 .deactivate = ledtrig_tty_deactivate,
351 .groups = ledtrig_tty_groups,
353 module_led_trigger(ledtrig_tty);
355 MODULE_AUTHOR("Uwe Kleine-König <u.kleine-koenig@pengutronix.de>");
356 MODULE_DESCRIPTION("UART LED trigger");
357 MODULE_LICENSE("GPL v2");