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1// SPDX-License-Identifier: GPL-2.02 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>8#include <linux/tty.h>9#include <uapi/linux/serial.h>10 11#define LEDTRIG_TTY_INTERVAL 5012 13struct ledtrig_tty_data {14 struct led_classdev *led_cdev;15 struct delayed_work dwork;16 struct completion sysfs;17 const char *ttyname;18 struct tty_struct *tty;19 int rx, tx;20 bool mode_rx;21 bool mode_tx;22 bool mode_cts;23 bool mode_dsr;24 bool mode_dcd;25 bool mode_rng;26};27 28/* Indicates which state the LED should now display */29enum led_trigger_tty_state {30 TTY_LED_BLINK,31 TTY_LED_ENABLE,32 TTY_LED_DISABLE,33};34 35enum led_trigger_tty_modes {36 TRIGGER_TTY_RX = 0,37 TRIGGER_TTY_TX,38 TRIGGER_TTY_CTS,39 TRIGGER_TTY_DSR,40 TRIGGER_TTY_DCD,41 TRIGGER_TTY_RNG,42};43 44static int ledtrig_tty_wait_for_completion(struct device *dev)45{46 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);47 int ret;48 49 ret = wait_for_completion_timeout(&trigger_data->sysfs,50 msecs_to_jiffies(LEDTRIG_TTY_INTERVAL * 20));51 if (ret == 0)52 return -ETIMEDOUT;53 54 return ret;55}56 57static ssize_t ttyname_show(struct device *dev,58 struct device_attribute *attr, char *buf)59{60 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);61 ssize_t len = 0;62 int completion;63 64 reinit_completion(&trigger_data->sysfs);65 completion = ledtrig_tty_wait_for_completion(dev);66 if (completion < 0)67 return completion;68 69 if (trigger_data->ttyname)70 len = sprintf(buf, "%s\n", trigger_data->ttyname);71 72 return len;73}74 75static ssize_t ttyname_store(struct device *dev,76 struct device_attribute *attr, const char *buf,77 size_t size)78{79 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);80 char *ttyname;81 ssize_t ret = size;82 int completion;83 84 if (size > 0 && buf[size - 1] == '\n')85 size -= 1;86 87 if (size) {88 ttyname = kmemdup_nul(buf, size, GFP_KERNEL);89 if (!ttyname)90 return -ENOMEM;91 } else {92 ttyname = NULL;93 }94 95 reinit_completion(&trigger_data->sysfs);96 completion = ledtrig_tty_wait_for_completion(dev);97 if (completion < 0)98 return completion;99 100 kfree(trigger_data->ttyname);101 tty_kref_put(trigger_data->tty);102 trigger_data->tty = NULL;103 104 trigger_data->ttyname = ttyname;105 106 return ret;107}108static DEVICE_ATTR_RW(ttyname);109 110static ssize_t ledtrig_tty_attr_show(struct device *dev, char *buf,111 enum led_trigger_tty_modes attr)112{113 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);114 bool state;115 116 switch (attr) {117 case TRIGGER_TTY_RX:118 state = trigger_data->mode_rx;119 break;120 case TRIGGER_TTY_TX:121 state = trigger_data->mode_tx;122 break;123 case TRIGGER_TTY_CTS:124 state = trigger_data->mode_cts;125 break;126 case TRIGGER_TTY_DSR:127 state = trigger_data->mode_dsr;128 break;129 case TRIGGER_TTY_DCD:130 state = trigger_data->mode_dcd;131 break;132 case TRIGGER_TTY_RNG:133 state = trigger_data->mode_rng;134 break;135 }136 137 return sysfs_emit(buf, "%u\n", state);138}139 140static ssize_t ledtrig_tty_attr_store(struct device *dev, const char *buf,141 size_t size, enum led_trigger_tty_modes attr)142{143 struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);144 bool state;145 int ret;146 147 ret = kstrtobool(buf, &state);148 if (ret)149 return ret;150 151 switch (attr) {152 case TRIGGER_TTY_RX:153 trigger_data->mode_rx = state;154 break;155 case TRIGGER_TTY_TX:156 trigger_data->mode_tx = state;157 break;158 case TRIGGER_TTY_CTS:159 trigger_data->mode_cts = state;160 break;161 case TRIGGER_TTY_DSR:162 trigger_data->mode_dsr = state;163 break;164 case TRIGGER_TTY_DCD:165 trigger_data->mode_dcd = state;166 break;167 case TRIGGER_TTY_RNG:168 trigger_data->mode_rng = state;169 break;170 }171 172 return size;173}174 175#define DEFINE_TTY_TRIGGER(trigger_name, trigger) \176 static ssize_t trigger_name##_show(struct device *dev, \177 struct device_attribute *attr, char *buf) \178 { \179 return ledtrig_tty_attr_show(dev, buf, trigger); \180 } \181 static ssize_t trigger_name##_store(struct device *dev, \182 struct device_attribute *attr, const char *buf, size_t size) \183 { \184 return ledtrig_tty_attr_store(dev, buf, size, trigger); \185 } \186 static DEVICE_ATTR_RW(trigger_name)187 188DEFINE_TTY_TRIGGER(rx, TRIGGER_TTY_RX);189DEFINE_TTY_TRIGGER(tx, TRIGGER_TTY_TX);190DEFINE_TTY_TRIGGER(cts, TRIGGER_TTY_CTS);191DEFINE_TTY_TRIGGER(dsr, TRIGGER_TTY_DSR);192DEFINE_TTY_TRIGGER(dcd, TRIGGER_TTY_DCD);193DEFINE_TTY_TRIGGER(rng, TRIGGER_TTY_RNG);194 195static void ledtrig_tty_work(struct work_struct *work)196{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;201 bool invert = false;202 int status;203 int ret;204 205 if (!trigger_data->ttyname)206 goto out;207 208 /* try to get the tty corresponding to $ttyname */209 if (!trigger_data->tty) {210 dev_t devno;211 struct tty_struct *tty;212 int ret;213 214 ret = tty_dev_name_to_number(trigger_data->ttyname, &devno);215 if (ret < 0)216 /*217 * A device with this name might appear later, so keep218 * retrying.219 */220 goto out;221 222 tty = tty_kopen_shared(devno);223 if (IS_ERR(tty) || !tty)224 /* What to do? retry or abort */225 goto out;226 227 trigger_data->tty = tty;228 }229 230 status = tty_get_tiocm(trigger_data->tty);231 if (status > 0) {232 if (trigger_data->mode_cts) {233 if (status & TIOCM_CTS)234 state = TTY_LED_ENABLE;235 }236 237 if (trigger_data->mode_dsr) {238 if (status & TIOCM_DSR)239 state = TTY_LED_ENABLE;240 }241 242 if (trigger_data->mode_dcd) {243 if (status & TIOCM_CAR)244 state = TTY_LED_ENABLE;245 }246 247 if (trigger_data->mode_rng) {248 if (status & TIOCM_RNG)249 state = TTY_LED_ENABLE;250 }251 }252 253 /*254 * The evaluation of rx/tx must be done after the evaluation255 * of TIOCM_*, because rx/tx has priority.256 */257 if (trigger_data->mode_rx || trigger_data->mode_tx) {258 struct serial_icounter_struct icount;259 260 ret = tty_get_icount(trigger_data->tty, &icount);261 if (ret)262 goto out;263 264 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;268 }269 270 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;274 }275 }276 277out:278 switch (state) {279 case TTY_LED_BLINK:280 led_blink_set_oneshot(trigger_data->led_cdev, &interval,281 &interval, invert);282 break;283 case TTY_LED_ENABLE:284 led_set_brightness(trigger_data->led_cdev,285 trigger_data->led_cdev->blink_brightness);286 break;287 case TTY_LED_DISABLE:288 fallthrough;289 default:290 led_set_brightness(trigger_data->led_cdev, LED_OFF);291 break;292 }293 294 complete_all(&trigger_data->sysfs);295 schedule_delayed_work(&trigger_data->dwork,296 msecs_to_jiffies(LEDTRIG_TTY_INTERVAL * 2));297}298 299static struct attribute *ledtrig_tty_attrs[] = {300 &dev_attr_ttyname.attr,301 &dev_attr_rx.attr,302 &dev_attr_tx.attr,303 &dev_attr_cts.attr,304 &dev_attr_dsr.attr,305 &dev_attr_dcd.attr,306 &dev_attr_rng.attr,307 NULL308};309ATTRIBUTE_GROUPS(ledtrig_tty);310 311static int ledtrig_tty_activate(struct led_classdev *led_cdev)312{313 struct ledtrig_tty_data *trigger_data;314 315 trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);316 if (!trigger_data)317 return -ENOMEM;318 319 /* Enable default rx/tx mode */320 trigger_data->mode_rx = true;321 trigger_data->mode_tx = true;322 323 led_set_trigger_data(led_cdev, trigger_data);324 325 INIT_DELAYED_WORK(&trigger_data->dwork, ledtrig_tty_work);326 trigger_data->led_cdev = led_cdev;327 init_completion(&trigger_data->sysfs);328 329 schedule_delayed_work(&trigger_data->dwork, 0);330 331 return 0;332}333 334static void ledtrig_tty_deactivate(struct led_classdev *led_cdev)335{336 struct ledtrig_tty_data *trigger_data = led_get_trigger_data(led_cdev);337 338 cancel_delayed_work_sync(&trigger_data->dwork);339 340 kfree(trigger_data->ttyname);341 tty_kref_put(trigger_data->tty);342 trigger_data->tty = NULL;343 344 kfree(trigger_data);345}346 347static struct led_trigger ledtrig_tty = {348 .name = "tty",349 .activate = ledtrig_tty_activate,350 .deactivate = ledtrig_tty_deactivate,351 .groups = ledtrig_tty_groups,352};353module_led_trigger(ledtrig_tty);354 355MODULE_AUTHOR("Uwe Kleine-König <u.kleine-koenig@pengutronix.de>");356MODULE_DESCRIPTION("UART LED trigger");357MODULE_LICENSE("GPL v2");358