[Patch v9 0/4] ledtrig-tty: add additional tty state evaluation

[Patch v9 0/4] ledtrig-tty: add additional tty state evaluation

[Florian Eckert]

Changes in v9:
==============
- As requested, I have removed the memory leak fix patch from the previous
  patch series v8 and have send this patch directly to the stable
  mailinglist [10].
- I also have removed the not needed wait for completion code path on
  sysfs attr store and show, for the new configuration options, as
  requested by greg k-h [11].
- Patch v8 3/6 dropped, because the change is not correct as mentiond
  by greg k-h [12] and this part of the code will be removed anyway
  in this patch series.
- Update naming of the function ledtrig_tty_waitforcompletion() to
  ledtrig_tty_wait_for_completion() which match better with the API call
  function wait_for_completion_timeout().

Thanks to all reviewers for the suggestions for improvement :+1: of this
patch set.

Links:
[10] https://lore.kernel.org/stable/2023112718-profane-dipped-a9a8@gregkh/T/#m6b36fde65a0ddacbe1fc94a14778a304775b2e79
[11] https://lore.kernel.org/linux-leds/2023112334-unquote-robust-15b8@gregkh/
[12] https://lore.kernel.org/linux-leds/2023112300-registrar-preface-2225@gregkh/

Changes in v8:
==============
v8: https://lore.kernel.org/linux-leds/20231109085038.371977-1-fe@dev.tdt.de/
- As requested by greg k-h [6], I have send the patch 2/7 of this series
  about the memory leak also to stable.vger.kernel.org [7]. This has
  already received a 'Reviewed-by' from Uwe [8].
- As requested by Maarten, I have adopted his suggestion to invert the LED
  blink, so that I do not have to save the 'state' in the tty data
  struct [9].

Links:
[6] https://lore.kernel.org/linux-leds/20231106123415.3365732-1-fe@dev.tdt.de/T/#me43be56f4063082e7b47858773ea8067a3846466
[7] https://lore.kernel.org/stable/20231106144914.bflq2jxejdxs6zjb@pengutronix.de/T/#t
[8] https://lore.kernel.org/stable/20231106144914.bflq2jxejdxs6zjb@pengutronix.de/T/#m78a946889e4722903b2a79e3a465d8da0ca16333
[9] https://lore.kernel.org/linux-leds/20231106123415.3365732-1-fe@dev.tdt.de/T/#m43df92b665f613fe0af7d5d003a3804404f1c494

Changes in v7:
==============
v7: https://lore.kernel.org/linux-leds/20231106123415.3365732-1-fe@dev.tdt.de/
- Patch 1/7 is no longer included from the previous patch set v6, as it has
  already been merged into the master branch [5].
- As requested by Maarten, I have added a 'Fixes:' tag to patch 2/6 of
  this patch set, so that this commit should also be backported to the
  stable branches, as it is a memory leak.
- As requested by Maarten, I added an invert flag on LED blink, so that
  the LED blinks in the correct order.
  * LED was 'on' in the previous round, then it should first go 'off' and
    then 'on' again when it should blink (data has been transferred).
  * LED was 'off' in the previous round, then it should first go 'on' and
    then 'off' again when it should blink (data has been transferred).

Links:
[5] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/tty/tty_io.c?h=next-20231106&id=838eb763c3e939a8de8d4c55a17ddcce737685c1

Changes in v6:
==============
v6: https://lore.kernel.org/linux-leds/20231030100447.63477-1-fe@dev.tdt.de/
This is a paritial rewrite of the changes to make the function for
setting the tty evaluation configurable. This change was requested and
comment by Greg K-H at the last review [1]. The main changes are.
- Split the changes into smaller commits to make reviewing easier.
- Use a completion to sync the sysfs and the delay scheduler work on
  shared variables.
- Adding the base-commit to this overview, that reviewer know which base
  commit I am using.
  Base branch is:
  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Patch [1/7]:
  This patch is already included in the tty branch [2], but it is still
  included in this patchsset, so that the following patches of the
  base-commit branch could be applied correctly.
Patch [2/7]:
  Add a new helper function tty_get_tiocm(). This got already a
  'Acked-by: Greg Kroah-Hartman' [3] and is not changed.
Patch [3/7]:
  Add missing of freeing an allocated ttyname buffer on trigger
  deactivation. This is a memory leak fix patch and should also be
  backported to the 'stable' branches.
Patch [4/7]:
  As requested by greg k-h this is more a 'dev_warn' instead of a
  'dev_info'. This could also be backported to the 'stable' branches if
  needed.
Patch [5/7]:
  Use a completion to sync for sysfs read/write and the delay scheduler
  work. I hope I am using the completion correctly. I wasn't sure if I
  should secure the sysfs read and write access at the same time via a
  mutex. With this change, the work is also not stopped as it was before
  when no ttyname was set via sysfs. A tty should always be set when this
  trigger is used. And is therefore not a problem from my point of view.
Patch [6/7]:
  Make rx tx activitate configurable. In the previous implementation,
  there was still the ttytrigger flag variable. This flag variable was
  replaced by individual variables in the data struct. Now these variables
  can be accessed without masking. The commit was rebased and cleaned up
  to use the completion implementation.
Patch [7/7]:
  Adding additional trigger line state sources. The commit was also
  rebased and cleaned up to use the completion implementation.

Changes in v5:
==============
v5: https://lore.kernel.org/linux-leds/20231023094205.2706812-1-fe@dev.tdt.de/
- Update commit message as request by greg k-h, to make the commit
  message more generic and not focusing on my use case [2].
- Removing PATCH v4 1/3 from previous set. This has been already applied
  to tty-testing [3] by greg k-h.
- As requested by greq k-h. I have also made the following changes to
  PATCH v4 3/3 [4].
  * Add a comment to the enum that this is already used for bit
    evaluation and sysfs read and write.
  * Renaming the variable 'unsigned long mode' to
    'unsigned long ttytrigger' in the ledtrig_tty_data structure to make
    it clearer that the selected triggers are stored there.
  * Using sysfs_emit() function to dump the requestd ttytrigger to
    userland.
  * Also using the kstrtobool() function to write the selected
    ttytrigger via the sysfs. This values are booleans.
- I also removed the function ledtrig_tty_evaluate() from my last
  patchses PATCH v4 3/3 [4]. The new API tty_get_tiocm() function
  is only called once now and checked for each ttytrigger bit.
  Previously this function was called for each bit, which is not
  necessary.

Links:
[2] https://lore.kernel.org/linux-leds/2023102115-stock-scrambled-f7d5@gregkh/
[3] https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git/commit/?h=tty-testing&id=838eb763c3e939a8de8d4c55a17ddcce737685c1
[4] https://lore.kernel.org/linux-leds/20231019112809.881730-4-fe@dev.tdt.de/

Changes in v4:
==============
v4: https://lore.kernel.org/linux-leds/20231019112809.881730-1-fe@dev.tdt.de/
- Merging patch 3/4 into patch number 4/4 from previous series, because
  it fixes a problem that does not exist upstream. This was a note from
  the build robot regarding my change that I added with previous series.
  This change was never upstream and therefore this is not relevant.
- Update the commit message of patch 1/3 of this series, that this
  commit
  also changes the 'ndashes' to simple dashes. There were no changes, so
  I add the 'Reviewed-by' that the commit received before.
- With this patchset version I have reworked my implementation for the
  evaluation of the additional line state, so that this changes becomes
  smaller. As basis I have used the staged commits from Christian Marangi
  that makes this changes to the netdev trigger. This has already been
  applied to 'for-leds-next-next' by Lee Jones. I adapted this to the
  tty trigger.
  Convert device attr to macro:
  https://git.kernel.org/pub/scm/linux/kernel/git/lee/leds.git/commit/drivers/leds/trigger?h=for-leds-next-next&id=509412749002f4bac4c29f2012fff90c08d8afca
  Unify sysfs and state handling:
  https://git.kernel.org/pub/scm/linux/kernel/git/lee/leds.git/commit/drivers/leds/trigger?h=for-leds-next-next&id=0fd93ac8582627bee9a3c824489f302dff722881

Changes in v3:
==============
v3: https://lore.kernel.org/linux-leds/20231016071332.597654-1-fe@dev.tdt.de/
- Add missing 'kernel test robot' information to the commit message.
- Additional information added to the commit message

Changes in v2:
==============
v2: https://lore.kernel.org/linux-leds/20230928132632.200263-1-fe@dev.tdt.de/
- rename new function from tty_get_mget() to tty_get_tiocm() as
  requested by 'Jiri Slaby'.
- As suggested by 'Jiri Slaby', fixed tabs in function documentation
  throughout the file '/drivers/tty/tty_io.c' in a separate commit.
- Move the variable definition to the top in function
  'ledtrig_tty_work()'.
  This was reported by the 'kernel test robot' after my change in v1.
- Also set the 'max_brightness' to 'blink_brightness' if no
  'blink_brightness' was set. This fixes a problem at startup when the
  brightness is still set to 0 and only 'line_*' is evaluated. I looked
  in the netdev trigger and that's exactly how it's done there.

Changes in v1:
==============
v1: https://lore.kernel.org/linux-leds/20230926093607.59536-1-fe@dev.tdt.de/
This is a follow-up patchset, based on the mailing list discussion from
March 2023 based on the old patchset v8 [1]. I have changed, the LED
trigger handling via the sysfs interfaces as suggested by Uwe
Kleine-König.
Links:
[1] https://lore.kernel.org/linux-leds/20230306094113.273988-1-fe@dev.tdt.de/

*** BLURB HERE ***

Florian Eckert (4):
  tty: add new helper function tty_get_tiocm
  leds: ledtrig-tty: replace mutex with completion
  leds: ledtrig-tty: make rx tx activitate configurable
  leds: ledtrig-tty: add additional line state evaluation

 .../ABI/testing/sysfs-class-led-trigger-tty   |  56 ++++
 drivers/leds/trigger/ledtrig-tty.c            | 243 +++++++++++++++---
 drivers/tty/tty_io.c                          |  28 +-
 include/linux/tty.h                           |   1 +
 4 files changed, 285 insertions(+), 43 deletions(-)


base-commit: 2cc14f52aeb78ce3f29677c2de1f06c0e91471ab
-- 
2.30.2

[Patch v9 1/4] tty: add new helper function tty_get_tiocm

[Florian Eckert]

There is no in-kernel function to get the status register of a tty device
like the TIOCMGET ioctl returns to userspace. Create a new function,
tty_get_tiocm(), to obtain the status register that other portions of the
kernel can call if they need this information, and move the existing
internal tty_tiocmget() function to use this interface.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Florian Eckert <fe@dev.tdt.de>
---
 drivers/tty/tty_io.c | 28 ++++++++++++++++++++++------
 include/linux/tty.h  |  1 +
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 06414e43e0b5..e2e93404133e 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2498,6 +2498,24 @@ static int send_break(struct tty_struct *tty, unsigned int duration)
 	return retval;
 }
 
+/**
+ * tty_get_tiocm - get tiocm status register
+ * @tty: tty device
+ *
+ * Obtain the modem status bits from the tty driver if the feature
+ * is supported.
+ */
+int tty_get_tiocm(struct tty_struct *tty)
+{
+	int retval = -ENOTTY;
+
+	if (tty->ops->tiocmget)
+		retval = tty->ops->tiocmget(tty);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(tty_get_tiocm);
+
 /**
  * tty_tiocmget - get modem status
  * @tty: tty device
@@ -2510,14 +2528,12 @@ static int send_break(struct tty_struct *tty, unsigned int duration)
  */
 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
 {
-	int retval = -ENOTTY;
+	int retval;
 
-	if (tty->ops->tiocmget) {
-		retval = tty->ops->tiocmget(tty);
+	retval = tty_get_tiocm(tty);
+	if (retval >= 0)
+		retval = put_user(retval, p);
 
-		if (retval >= 0)
-			retval = put_user(retval, p);
-	}
 	return retval;
 }
 
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 4b6340ac2af2..d219a11e3fe0 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -419,6 +419,7 @@ bool tty_unthrottle_safe(struct tty_struct *tty);
 int tty_do_resize(struct tty_struct *tty, struct winsize *ws);
 int tty_get_icount(struct tty_struct *tty,
 		struct serial_icounter_struct *icount);
+int tty_get_tiocm(struct tty_struct *tty);
 int is_current_pgrp_orphaned(void);
 void tty_hangup(struct tty_struct *tty);
 void tty_vhangup(struct tty_struct *tty);
-- 
2.30.2

[Patch v9 2/4] leds: ledtrig-tty: replace mutex with completion

[Florian Eckert]

With this commit, the mutex handling is replaced by the completion
handling. When handling mutex, it must always be ensured that the held
mutex is also released again. This is more error-prone should the number
of code paths increase.

This is a preparatory commit to make the trigger more configurable via
additional sysfs parameters. With this change, the worker always runs and
is no longer stopped if no ttyname is set.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>
---
 drivers/leds/trigger/ledtrig-tty.c | 59 +++++++++++++++---------------
 1 file changed, 30 insertions(+), 29 deletions(-)

diff --git a/drivers/leds/trigger/ledtrig-tty.c b/drivers/leds/trigger/ledtrig-tty.c
index 8ae0d2d284af..0d73bec1529f 100644
--- a/drivers/leds/trigger/ledtrig-tty.c
+++ b/drivers/leds/trigger/ledtrig-tty.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
+#include <linux/completion.h>
 #include <linux/delay.h>
 #include <linux/leds.h>
 #include <linux/module.h>
@@ -12,15 +13,23 @@
 struct ledtrig_tty_data {
 	struct led_classdev *led_cdev;
 	struct delayed_work dwork;
-	struct mutex mutex;
+	struct completion sysfs;
 	const char *ttyname;
 	struct tty_struct *tty;
 	int rx, tx;
 };
 
-static void ledtrig_tty_restart(struct ledtrig_tty_data *trigger_data)
+static int ledtrig_tty_wait_for_completion(struct device *dev)
 {
-	schedule_delayed_work(&trigger_data->dwork, 0);
+	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,
@@ -28,14 +37,16 @@ static ssize_t ttyname_show(struct device *dev,
 {
 	struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
 	ssize_t len = 0;
+	int completion;
 
-	mutex_lock(&trigger_data->mutex);
+	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);
 
-	mutex_unlock(&trigger_data->mutex);
-
 	return len;
 }
 
@@ -46,7 +57,7 @@ static ssize_t ttyname_store(struct device *dev,
 	struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
 	char *ttyname;
 	ssize_t ret = size;
-	bool running;
+	int completion;
 
 	if (size > 0 && buf[size - 1] == '\n')
 		size -= 1;
@@ -59,9 +70,10 @@ static ssize_t ttyname_store(struct device *dev,
 		ttyname = NULL;
 	}
 
-	mutex_lock(&trigger_data->mutex);
-
-	running = trigger_data->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);
@@ -69,11 +81,6 @@ static ssize_t ttyname_store(struct device *dev,
 
 	trigger_data->ttyname = ttyname;
 
-	mutex_unlock(&trigger_data->mutex);
-
-	if (ttyname && !running)
-		ledtrig_tty_restart(trigger_data);
-
 	return ret;
 }
 static DEVICE_ATTR_RW(ttyname);
@@ -85,13 +92,8 @@ static void ledtrig_tty_work(struct work_struct *work)
 	struct serial_icounter_struct icount;
 	int ret;
 
-	mutex_lock(&trigger_data->mutex);
-
-	if (!trigger_data->ttyname) {
-		/* exit without rescheduling */
-		mutex_unlock(&trigger_data->mutex);
-		return;
-	}
+	if (!trigger_data->ttyname)
+		goto out;
 
 	/* try to get the tty corresponding to $ttyname */
 	if (!trigger_data->tty) {
@@ -116,11 +118,8 @@ static void ledtrig_tty_work(struct work_struct *work)
 	}
 
 	ret = tty_get_icount(trigger_data->tty, &icount);
-	if (ret) {
-		dev_info(trigger_data->tty->dev, "Failed to get icount, stopped polling\n");
-		mutex_unlock(&trigger_data->mutex);
-		return;
-	}
+	if (ret)
+		goto out;
 
 	if (icount.rx != trigger_data->rx ||
 	    icount.tx != trigger_data->tx) {
@@ -134,7 +133,7 @@ static void ledtrig_tty_work(struct work_struct *work)
 	}
 
 out:
-	mutex_unlock(&trigger_data->mutex);
+	complete_all(&trigger_data->sysfs);
 	schedule_delayed_work(&trigger_data->dwork,
 			      msecs_to_jiffies(LEDTRIG_TTY_INTERVAL * 2));
 }
@@ -157,7 +156,9 @@ static int ledtrig_tty_activate(struct led_classdev *led_cdev)
 
 	INIT_DELAYED_WORK(&trigger_data->dwork, ledtrig_tty_work);
 	trigger_data->led_cdev = led_cdev;
-	mutex_init(&trigger_data->mutex);
+	init_completion(&trigger_data->sysfs);
+
+	schedule_delayed_work(&trigger_data->dwork, 0);
 
 	return 0;
 }
-- 
2.30.2

[Patch v9 3/4] leds: ledtrig-tty: make rx tx activitate configurable

[Florian Eckert]

Until now, the LED blinks when data is sent via the tty (rx/tx).
This is not configurable.

This change adds the possibility to make the indication for the direction
of the transmitted data independently controllable via the new rx and
tx sysfs entries.

- rx:
  Signal reception (rx) of data on the named tty device.
  If set to 0, the LED will not blink on reception.
  If set to 1 (default), the LED will blink on reception.

- tx:
  Signal transmission (tx) of data on the named tty device.
  If set to 0, the LED will not blink on transmission.
  If set to 1 (default), the LED will blink on transmission.

This new sysfs entry are on by default. Thus the trigger behaves as
before this change.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>
---
 .../ABI/testing/sysfs-class-led-trigger-tty   |  16 +++
 drivers/leds/trigger/ledtrig-tty.c            | 114 ++++++++++++++++--
 2 files changed, 119 insertions(+), 11 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-tty b/Documentation/ABI/testing/sysfs-class-led-trigger-tty
index 2bf6b24e781b..504dece151b8 100644
--- a/Documentation/ABI/testing/sysfs-class-led-trigger-tty
+++ b/Documentation/ABI/testing/sysfs-class-led-trigger-tty
@@ -4,3 +4,19 @@ KernelVersion:	5.10
 Contact:	linux-leds@vger.kernel.org
 Description:
 		Specifies the tty device name of the triggering tty
+
+What:		/sys/class/leds/<led>/rx
+Date:		February 2024
+KernelVersion:	6.8
+Description:
+		Signal reception (rx) of data on the named tty device.
+		If set to 0, the LED will not blink on reception.
+		If set to 1 (default), the LED will blink on reception.
+
+What:		/sys/class/leds/<led>/tx
+Date:		February 2024
+KernelVersion:	6.8
+Description:
+		Signal transmission (tx) of data on the named tty device.
+		If set to 0, the LED will not blink on transmission.
+		If set to 1 (default), the LED will blink on transmission.
diff --git a/drivers/leds/trigger/ledtrig-tty.c b/drivers/leds/trigger/ledtrig-tty.c
index 0d73bec1529f..ee6d01ecb309 100644
--- a/drivers/leds/trigger/ledtrig-tty.c
+++ b/drivers/leds/trigger/ledtrig-tty.c
@@ -17,6 +17,19 @@ struct ledtrig_tty_data {
 	const char *ttyname;
 	struct tty_struct *tty;
 	int rx, tx;
+	bool mode_rx;
+	bool mode_tx;
+};
+
+/* Indicates which state the LED should now display */
+enum led_trigger_tty_state {
+	TTY_LED_BLINK,
+	TTY_LED_DISABLE,
+};
+
+enum led_trigger_tty_modes {
+	TRIGGER_TTY_RX = 0,
+	TRIGGER_TTY_TX,
 };
 
 static int ledtrig_tty_wait_for_completion(struct device *dev)
@@ -85,11 +98,69 @@ static ssize_t ttyname_store(struct device *dev,
 }
 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;
+	}
+
+	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;
+	}
+
+	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);
+
 static void ledtrig_tty_work(struct work_struct *work)
 {
 	struct ledtrig_tty_data *trigger_data =
 		container_of(work, struct ledtrig_tty_data, dwork.work);
-	struct serial_icounter_struct icount;
+	enum led_trigger_tty_state state = TTY_LED_DISABLE;
+	unsigned long interval = LEDTRIG_TTY_INTERVAL;
 	int ret;
 
 	if (!trigger_data->ttyname)
@@ -117,22 +188,37 @@ static void ledtrig_tty_work(struct work_struct *work)
 		trigger_data->tty = tty;
 	}
 
-	ret = tty_get_icount(trigger_data->tty, &icount);
-	if (ret)
-		goto out;
+	if (trigger_data->mode_rx || trigger_data->mode_tx) {
+		struct serial_icounter_struct icount;
 
-	if (icount.rx != trigger_data->rx ||
-	    icount.tx != trigger_data->tx) {
-		unsigned long interval = LEDTRIG_TTY_INTERVAL;
+		ret = tty_get_icount(trigger_data->tty, &icount);
+		if (ret)
+			goto out;
 
-		led_blink_set_oneshot(trigger_data->led_cdev, &interval,
-				      &interval, 0);
+		if (trigger_data->mode_tx && (icount.tx != trigger_data->tx)) {
+			trigger_data->tx = icount.tx;
+			state = TTY_LED_BLINK;
+		}
 
-		trigger_data->rx = icount.rx;
-		trigger_data->tx = icount.tx;
+		if (trigger_data->mode_rx && (icount.rx != trigger_data->rx)) {
+			trigger_data->rx = icount.rx;
+			state = TTY_LED_BLINK;
+		}
 	}
 
 out:
+	switch (state) {
+	case TTY_LED_BLINK:
+		led_blink_set_oneshot(trigger_data->led_cdev, &interval,
+				&interval, 0);
+		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));
@@ -140,6 +226,8 @@ static void ledtrig_tty_work(struct work_struct *work)
 
 static struct attribute *ledtrig_tty_attrs[] = {
 	&dev_attr_ttyname.attr,
+	&dev_attr_rx.attr,
+	&dev_attr_tx.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(ledtrig_tty);
@@ -152,6 +240,10 @@ static int ledtrig_tty_activate(struct led_classdev *led_cdev)
 	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);
-- 
2.30.2

[Patch v9 4/4] leds: ledtrig-tty: add additional line state evaluation

[Florian Eckert]

The serial tty interface also supports additional input signals, that
can also be evaluated within this trigger. This change is adding the
following additional input sources, which could be controlled
via the '/sys/class/<leds>/' sysfs interface.

Explanation:
DCE = Data Communication Equipment (Modem)
DTE = Data Terminal Equipment (Computer)

- cts:
  DCE is ready to accept data from the DTE (CTS = Clear To Send). If
  the line state is detected, the LED is switched on.
  If set to 0 (default), the LED will not evaluate CTS.
  If set to 1, the LED will evaluate CTS.

- dsr:
  DCE is ready to receive and send data (DSR = Data Set Ready). If the
  line state is detected, the LED is switched on.
  If set to 0 (default), the LED will not evaluate DSR.
  If set to 1, the LED will evaluate DSR.

- dcd:
  DTE is receiving a carrier from the DCE (DCD = Data Carrier Detect).
  If the line state is detected, the LED is switched on.
  If set to 0 (default), the LED will not evaluate DCD.
  If set to 1, the LED will evaluate DCD.

- rng:
  DCE has detected an incoming ring signal on the telephone line
  (RNG = Ring Indicator). If the line state is detected, the LED is
  switched on.
  If set to 0 (default), the LED will not evaluate RNG.
  If set to 1, the LED will evaluate RNG.

Also add an invert flag on LED blink, so that the LED blinks in the
correct order.

* If one off the new enabled input signals are evaluatet as 'enabled',
  and data are transmitted, then the LED should first blink 'off' and
  then 'on' (invert).
* If all the new enabled input signals are evaluatet as 'disabled',
  and data are transmitted, then the LED should first blink 'on' and
  then 'off'.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>
Reviewed-by: Maarten Brock <m.brock@vanmierlo.com>
---
 .../ABI/testing/sysfs-class-led-trigger-tty   | 40 ++++++++++
 drivers/leds/trigger/ledtrig-tty.c            | 78 ++++++++++++++++++-
 2 files changed, 117 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-tty b/Documentation/ABI/testing/sysfs-class-led-trigger-tty
index 504dece151b8..30cef9ac0f49 100644
--- a/Documentation/ABI/testing/sysfs-class-led-trigger-tty
+++ b/Documentation/ABI/testing/sysfs-class-led-trigger-tty
@@ -20,3 +20,43 @@ Description:
 		Signal transmission (tx) of data on the named tty device.
 		If set to 0, the LED will not blink on transmission.
 		If set to 1 (default), the LED will blink on transmission.
+
+What:		/sys/class/leds/<led>/cts
+Date:		February 2024
+KernelVersion:	6.8
+Description:
+		CTS = Clear To Send
+		DCE is ready to accept data from the DTE.
+		If the line state is detected, the LED is switched on.
+		If set to 0 (default), the LED will not evaluate CTS.
+		If set to 1, the LED will evaluate CTS.
+
+What:		/sys/class/leds/<led>/dsr
+Date:		February 2024
+KernelVersion:	6.8
+Description:
+		DSR = Data Set Ready
+		DCE is ready to receive and send data.
+		If the line state is detected, the LED is switched on.
+		If set to 0 (default), the LED will not evaluate DSR.
+		If set to 1, the LED will evaluate DSR.
+
+What:		/sys/class/leds/<led>/dcd
+Date:		February 2024
+KernelVersion:	6.8
+Description:
+		DCD = Data Carrier Detect
+		DTE is receiving a carrier from the DCE.
+		If the line state is detected, the LED is switched on.
+		If set to 0 (default), the LED will not evaluate CAR (DCD).
+		If set to 1, the LED will evaluate CAR (DCD).
+
+What:		/sys/class/leds/<led>/rng
+Date:		February 2024
+KernelVersion:	6.8
+Description:
+		RNG = Ring Indicator
+		DCE has detected an incoming ring signal on the telephone
+		line. If the line state is detected, the LED is switched on.
+		If set to 0 (default), the LED will not evaluate RNG.
+		If set to 1, the LED will evaluate RNG.
diff --git a/drivers/leds/trigger/ledtrig-tty.c b/drivers/leds/trigger/ledtrig-tty.c
index ee6d01ecb309..e30926424c48 100644
--- a/drivers/leds/trigger/ledtrig-tty.c
+++ b/drivers/leds/trigger/ledtrig-tty.c
@@ -19,17 +19,26 @@ struct ledtrig_tty_data {
 	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)
@@ -111,6 +120,18 @@ static ssize_t ledtrig_tty_attr_show(struct device *dev, char *buf,
 	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);
@@ -134,6 +155,18 @@ static ssize_t ledtrig_tty_attr_store(struct device *dev, const char *buf,
 	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;
@@ -154,6 +187,10 @@ static ssize_t ledtrig_tty_attr_store(struct device *dev, const char *buf,
 
 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)
 {
@@ -161,6 +198,8 @@ static void ledtrig_tty_work(struct work_struct *work)
 		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)
@@ -188,6 +227,33 @@ static void ledtrig_tty_work(struct work_struct *work)
 		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;
 
@@ -197,11 +263,13 @@ static void ledtrig_tty_work(struct work_struct *work)
 
 		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;
 		}
 	}
@@ -210,7 +278,11 @@ static void ledtrig_tty_work(struct work_struct *work)
 	switch (state) {
 	case TTY_LED_BLINK:
 		led_blink_set_oneshot(trigger_data->led_cdev, &interval,
-				&interval, 0);
+				&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;
@@ -228,6 +300,10 @@ 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);
-- 
2.30.2

Re: [Patch v9 0/4] ledtrig-tty: add additional tty state evaluation

[Greg KH]

On Mon, Nov 27, 2023 at 12:03:07PM +0100, Florian Eckert wrote:
> Changes in v9:
> ==============
> - As requested, I have removed the memory leak fix patch from the previous
>   patch series v8 and have send this patch directly to the stable
>   mailinglist [10].
> - I also have removed the not needed wait for completion code path on
>   sysfs attr store and show, for the new configuration options, as
>   requested by greg k-h [11].
> - Patch v8 3/6 dropped, because the change is not correct as mentiond
>   by greg k-h [12] and this part of the code will be removed anyway
>   in this patch series.
> - Update naming of the function ledtrig_tty_waitforcompletion() to
>   ledtrig_tty_wait_for_completion() which match better with the API call
>   function wait_for_completion_timeout().
> 
> Thanks to all reviewers for the suggestions for improvement :+1: of this
> patch set.

Nice work, thanks for sticking with it:

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [Patch v9 0/4] ledtrig-tty: add additional tty state evaluation

[Lee Jones]

On Mon, 27 Nov 2023 12:03:07 +0100, Florian Eckert wrote:
> Changes in v9:
> ==============
> - As requested, I have removed the memory leak fix patch from the previous
>   patch series v8 and have send this patch directly to the stable
>   mailinglist [10].
> - I also have removed the not needed wait for completion code path on
>   sysfs attr store and show, for the new configuration options, as
>   requested by greg k-h [11].
> - Patch v8 3/6 dropped, because the change is not correct as mentiond
>   by greg k-h [12] and this part of the code will be removed anyway
>   in this patch series.
> - Update naming of the function ledtrig_tty_waitforcompletion() to
>   ledtrig_tty_wait_for_completion() which match better with the API call
>   function wait_for_completion_timeout().
> 
> [...]

Applied, thanks!

[1/4] tty: add new helper function tty_get_tiocm
      commit: 5d11a4709f552fa139c2439fead05daeb064a6f4
[2/4] leds: ledtrig-tty: replace mutex with completion
      commit: 50744fe65a4c8b78eff9a4b70825dd7c768f9f69
[3/4] leds: ledtrig-tty: make rx tx activitate configurable
      commit: 8e7b857c0eafdc49ff0e63e9252ed0273b9efdbd
[4/4] leds: ledtrig-tty: add additional line state evaluation
      commit: 7f5a46671b2253989b2674407d624f1fcc77d60f

--
Lee Jones [李琼斯]