diff options
Diffstat (limited to 'drivers/leds/trigger/ledtrig-tty.c')
| -rw-r--r-- | drivers/leds/trigger/ledtrig-tty.c | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/drivers/leds/trigger/ledtrig-tty.c b/drivers/leds/trigger/ledtrig-tty.c new file mode 100644 index 000000000000..8cf1485e8165 --- /dev/null +++ b/drivers/leds/trigger/ledtrig-tty.c @@ -0,0 +1,357 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/completion.h> +#include <linux/delay.h> +#include <linux/leds.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/tty.h> +#include <uapi/linux/serial.h> + +#define LEDTRIG_TTY_INTERVAL 50 + +struct ledtrig_tty_data { + struct led_classdev *led_cdev; + struct delayed_work dwork; + struct completion sysfs; + const char *ttyname; + struct tty_struct *tty; + int rx, tx; + bool mode_rx; + bool mode_tx; + bool mode_cts; + bool mode_dsr; + bool mode_dcd; + bool mode_rng; +}; + +/* Indicates which state the LED should now display */ +enum led_trigger_tty_state { + TTY_LED_BLINK, + TTY_LED_ENABLE, + TTY_LED_DISABLE, +}; + +enum led_trigger_tty_modes { + TRIGGER_TTY_RX = 0, + TRIGGER_TTY_TX, + TRIGGER_TTY_CTS, + TRIGGER_TTY_DSR, + TRIGGER_TTY_DCD, + TRIGGER_TTY_RNG, +}; + +static int ledtrig_tty_wait_for_completion(struct device *dev) +{ + struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev); + int ret; + + ret = wait_for_completion_timeout(&trigger_data->sysfs, + msecs_to_jiffies(LEDTRIG_TTY_INTERVAL * 20)); + if (ret == 0) + return -ETIMEDOUT; + + return ret; +} + +static ssize_t ttyname_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev); + ssize_t len = 0; + int completion; + + reinit_completion(&trigger_data->sysfs); + completion = ledtrig_tty_wait_for_completion(dev); + if (completion < 0) + return completion; + + if (trigger_data->ttyname) + len = sprintf(buf, "%s\n", trigger_data->ttyname); + + return len; +} + +static ssize_t ttyname_store(struct device *dev, + struct device_attribute *attr, const char *buf, + size_t size) +{ + struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev); + char *ttyname; + ssize_t ret = size; + int completion; + + if (size > 0 && buf[size - 1] == '\n') + size -= 1; + + if (size) { + ttyname = kmemdup_nul(buf, size, GFP_KERNEL); + if (!ttyname) + return -ENOMEM; + } else { + ttyname = NULL; + } + + reinit_completion(&trigger_data->sysfs); + completion = ledtrig_tty_wait_for_completion(dev); + if (completion < 0) + return completion; + + kfree(trigger_data->ttyname); + tty_kref_put(trigger_data->tty); + trigger_data->tty = NULL; + + trigger_data->ttyname = ttyname; + + return ret; +} +static DEVICE_ATTR_RW(ttyname); + +static ssize_t ledtrig_tty_attr_show(struct device *dev, char *buf, + enum led_trigger_tty_modes attr) +{ + struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev); + bool state; + + switch (attr) { + case TRIGGER_TTY_RX: + state = trigger_data->mode_rx; + break; + case TRIGGER_TTY_TX: + state = trigger_data->mode_tx; + break; + case TRIGGER_TTY_CTS: + state = trigger_data->mode_cts; + break; + case TRIGGER_TTY_DSR: + state = trigger_data->mode_dsr; + break; + case TRIGGER_TTY_DCD: + state = trigger_data->mode_dcd; + break; + case TRIGGER_TTY_RNG: + state = trigger_data->mode_rng; + break; + } + + return sysfs_emit(buf, "%u\n", state); +} + +static ssize_t ledtrig_tty_attr_store(struct device *dev, const char *buf, + size_t size, enum led_trigger_tty_modes attr) +{ + struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev); + bool state; + int ret; + + ret = kstrtobool(buf, &state); + if (ret) + return ret; + + switch (attr) { + case TRIGGER_TTY_RX: + trigger_data->mode_rx = state; + break; + case TRIGGER_TTY_TX: + trigger_data->mode_tx = state; + break; + case TRIGGER_TTY_CTS: + trigger_data->mode_cts = state; + break; + case TRIGGER_TTY_DSR: + trigger_data->mode_dsr = state; + break; + case TRIGGER_TTY_DCD: + trigger_data->mode_dcd = state; + break; + case TRIGGER_TTY_RNG: + trigger_data->mode_rng = state; + break; + } + + return size; +} + +#define DEFINE_TTY_TRIGGER(trigger_name, trigger) \ + static ssize_t trigger_name##_show(struct device *dev, \ + struct device_attribute *attr, char *buf) \ + { \ + return ledtrig_tty_attr_show(dev, buf, trigger); \ + } \ + static ssize_t trigger_name##_store(struct device *dev, \ + struct device_attribute *attr, const char *buf, size_t size) \ + { \ + return ledtrig_tty_attr_store(dev, buf, size, trigger); \ + } \ + static DEVICE_ATTR_RW(trigger_name) + +DEFINE_TTY_TRIGGER(rx, TRIGGER_TTY_RX); +DEFINE_TTY_TRIGGER(tx, TRIGGER_TTY_TX); +DEFINE_TTY_TRIGGER(cts, TRIGGER_TTY_CTS); +DEFINE_TTY_TRIGGER(dsr, TRIGGER_TTY_DSR); +DEFINE_TTY_TRIGGER(dcd, TRIGGER_TTY_DCD); +DEFINE_TTY_TRIGGER(rng, TRIGGER_TTY_RNG); + +static void ledtrig_tty_work(struct work_struct *work) +{ + struct ledtrig_tty_data *trigger_data = + container_of(work, struct ledtrig_tty_data, dwork.work); + enum led_trigger_tty_state state = TTY_LED_DISABLE; + unsigned long interval = LEDTRIG_TTY_INTERVAL; + bool invert = false; + int status; + int ret; + + if (!trigger_data->ttyname) + goto out; + + /* try to get the tty corresponding to $ttyname */ + if (!trigger_data->tty) { + dev_t devno; + struct tty_struct *tty; + int ret; + + ret = tty_dev_name_to_number(trigger_data->ttyname, &devno); + if (ret < 0) + /* + * A device with this name might appear later, so keep + * retrying. + */ + goto out; + + tty = tty_kopen_shared(devno); + if (IS_ERR(tty) || !tty) + /* What to do? retry or abort */ + goto out; + + trigger_data->tty = tty; + } + + status = tty_get_tiocm(trigger_data->tty); + if (status > 0) { + if (trigger_data->mode_cts) { + if (status & TIOCM_CTS) + state = TTY_LED_ENABLE; + } + + if (trigger_data->mode_dsr) { + if (status & TIOCM_DSR) + state = TTY_LED_ENABLE; + } + + if (trigger_data->mode_dcd) { + if (status & TIOCM_CAR) + state = TTY_LED_ENABLE; + } + + if (trigger_data->mode_rng) { + if (status & TIOCM_RNG) + state = TTY_LED_ENABLE; + } + } + + /* + * The evaluation of rx/tx must be done after the evaluation + * of TIOCM_*, because rx/tx has priority. + */ + if (trigger_data->mode_rx || trigger_data->mode_tx) { + struct serial_icounter_struct icount; + + ret = tty_get_icount(trigger_data->tty, &icount); + if (ret) + goto out; + + if (trigger_data->mode_tx && (icount.tx != trigger_data->tx)) { + trigger_data->tx = icount.tx; + invert = state == TTY_LED_ENABLE; + state = TTY_LED_BLINK; + } + + if (trigger_data->mode_rx && (icount.rx != trigger_data->rx)) { + trigger_data->rx = icount.rx; + invert = state == TTY_LED_ENABLE; + state = TTY_LED_BLINK; + } + } + +out: + switch (state) { + case TTY_LED_BLINK: + led_blink_set_oneshot(trigger_data->led_cdev, &interval, + &interval, invert); + break; + case TTY_LED_ENABLE: + led_set_brightness(trigger_data->led_cdev, + trigger_data->led_cdev->blink_brightness); + break; + case TTY_LED_DISABLE: + fallthrough; + default: + led_set_brightness(trigger_data->led_cdev, LED_OFF); + break; + } + + complete_all(&trigger_data->sysfs); + schedule_delayed_work(&trigger_data->dwork, + msecs_to_jiffies(LEDTRIG_TTY_INTERVAL * 2)); +} + +static struct attribute *ledtrig_tty_attrs[] = { + &dev_attr_ttyname.attr, + &dev_attr_rx.attr, + &dev_attr_tx.attr, + &dev_attr_cts.attr, + &dev_attr_dsr.attr, + &dev_attr_dcd.attr, + &dev_attr_rng.attr, + NULL +}; +ATTRIBUTE_GROUPS(ledtrig_tty); + +static int ledtrig_tty_activate(struct led_classdev *led_cdev) +{ + struct ledtrig_tty_data *trigger_data; + + trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL); + if (!trigger_data) + return -ENOMEM; + + /* Enable default rx/tx mode */ + trigger_data->mode_rx = true; + trigger_data->mode_tx = true; + + led_set_trigger_data(led_cdev, trigger_data); + + INIT_DELAYED_WORK(&trigger_data->dwork, ledtrig_tty_work); + trigger_data->led_cdev = led_cdev; + init_completion(&trigger_data->sysfs); + + schedule_delayed_work(&trigger_data->dwork, 0); + + return 0; +} + +static void ledtrig_tty_deactivate(struct led_classdev *led_cdev) +{ + struct ledtrig_tty_data *trigger_data = led_get_trigger_data(led_cdev); + + cancel_delayed_work_sync(&trigger_data->dwork); + + kfree(trigger_data->ttyname); + tty_kref_put(trigger_data->tty); + trigger_data->tty = NULL; + + kfree(trigger_data); +} + +static struct led_trigger ledtrig_tty = { + .name = "tty", + .activate = ledtrig_tty_activate, + .deactivate = ledtrig_tty_deactivate, + .groups = ledtrig_tty_groups, +}; +module_led_trigger(ledtrig_tty); + +MODULE_AUTHOR("Uwe Kleine-König <u.kleine-koenig@pengutronix.de>"); +MODULE_DESCRIPTION("UART LED trigger"); +MODULE_LICENSE("GPL v2"); |