[PATCH v2 0/2] LED: Add fault state handling to LP5860 LED

[PATCH v2 0/2] LED: Add fault state handling to LP5860 LED

[Steffen Trumtrar]

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
---
Changes in v2:
- make some functions/defines clearer
- minor newline cleanups
- split sysfs patch into own patch
- fix scope of some variables
- Link to v1: https://lore.kernel.org/r/20260129-v6-19-topic-ti-lp5860-fault-v1-1-49c812dc06da@pengutronix.de

---
Steffen Trumtrar (2):
      led: lp5860: expose fault state via sysfs
      leds: lp5860: detect and report fault state

 Documentation/ABI/testing/sysfs-class-spi-lp5860 |  49 ++++++++
 drivers/leds/rgb/leds-lp5860-core.c              | 143 +++++++++++++++++++++++
 include/linux/platform_data/leds-lp5860.h        |  19 ++-
 3 files changed, 208 insertions(+), 3 deletions(-)
---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20260129-v6-19-topic-ti-lp5860-fault-c8bd1f59fc3f
prerequisite-message-id: <20260309-v6-14-topic-ti-lp5860-v7-1-b1ed6c6a47ce@pengutronix.de>
prerequisite-patch-id: 45e295aab0d3ea7d92bf71596f8b0e18e8621ac0

Best regards,
-- 
Steffen Trumtrar <s.trumtrar@pengutronix.de>

[PATCH v2 1/2] led: lp5860: expose fault state via sysfs

[Steffen Trumtrar]

Return the fault state to the userspase via sysfs and allow to reset it.

The LP5860 has a global fault state, that just indicates that a short or
open fault was detected on any LED. This is exposed via 'fault_state'.

The 'fault_state_open' exposes the LED name and channel where an open
condition was detected.

The 'fault_state_short' exposes the LED name and channel where a short
condition was detected.

To: Mark Brown <broonie@kernel.org>
Cc: linux-spi@vger.kernel.org
Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
---
 Documentation/ABI/testing/sysfs-class-spi-lp5860 | 49 ++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-class-spi-lp5860 b/Documentation/ABI/testing/sysfs-class-spi-lp5860
new file mode 100644
index 0000000000000..31082bd78f51e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-spi-lp5860
@@ -0,0 +1,49 @@
+What:           /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state
+Date:           March 2026
+KernelVersion:  7.0
+Contact:        Steffen Trumtrar <kernel@pengutronix.de>
+Description:
+	Contains and sets the global fault state:
+
+	* 3: Open and short detected
+	* 2: Open detected
+	* 1: Short detected
+
+	Can be cleared by writing the corresponding value back to fault_state.
+
+	Example usage::
+
+		## Read
+		# cat /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state
+		2
+
+		## Write
+		# echo 2 > /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state
+
+What:           /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state_open
+Date:           March 2026
+KernelVersion:  7.0
+Contact:        Steffen Trumtrar <kernel@pengutronix.de>
+Description:
+	Contains all LEDs and channels where an open condition was detected.
+	The format is ledname:channel.
+
+	Example usage::
+
+		## Read
+		# cat /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state_open
+		rgb1:0 rgb2:4
+
+What:           /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state_short
+Date:           March 2026
+KernelVersion:  7.0
+Contact:        Steffen Trumtrar <kernel@pengutronix.de>
+Description:
+	Contains all LEDs and channels where a short condition was detected.
+	The format is ledname:channel.
+
+	Example usage::
+
+		## Read
+		# cat /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state_short
+		rgb1:0 rgb2:4

-- 
2.51.0

Re: [PATCH v2 1/2] led: lp5860: expose fault state via sysfs

[Lee Jones]

On Wed, 11 Mar 2026, Steffen Trumtrar wrote:

> Return the fault state to the userspase via sysfs and allow to reset it.

"userspace" is misspelled here and in the subject line.

> 
> The LP5860 has a global fault state, that just indicates that a short or
> open fault was detected on any LED. This is exposed via 'fault_state'.
> 
> The 'fault_state_open' exposes the LED name and channel where an open
> condition was detected.
> 
> The 'fault_state_short' exposes the LED name and channel where a short
> condition was detected.
> 
> To: Mark Brown <broonie@kernel.org>
> Cc: linux-spi@vger.kernel.org

These should be below the --- marker.

> Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> ---
>  Documentation/ABI/testing/sysfs-class-spi-lp5860 | 49 ++++++++++++++++++++++++

You're the first write driver documentation like this.

That has to tell you something.

>  1 file changed, 49 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-spi-lp5860 b/Documentation/ABI/testing/sysfs-class-spi-lp5860
> new file mode 100644
> index 0000000000000..31082bd78f51e
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-spi-lp5860
> @@ -0,0 +1,49 @@
> +What:           /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state

I believe this path is incorrect. Attributes for an SPI slave device should
be under `/sys/bus/spi/devices/spi<bus>.<dev>/`, not under the master
device's class directory.

> +Date:           March 2026
> +KernelVersion:  7.0
> +Contact:        Steffen Trumtrar <kernel@pengutronix.de>

This is different to your sign-off address.

> +Description:
> +	Contains and sets the global fault state:
> +
> +	* 3: Open and short detected
> +	* 2: Open detected
> +	* 1: Short detected

Exposing a raw bitmask like this is not a good ABI. The sysfs convention is
"one value per file". It would be better to have separate read-only files
like `fault_short` and `fault_open` which would contain "1" if a fault is
active and "0" otherwise.

> +
> +	Can be cleared by writing the corresponding value back to fault_state.

This "write back what you read" mechanism is non-standard and racy. A
better approach is to provide a separate write-only `fault_clear` file, or
allow writing '0' to the individual fault files to clear them.

> +
> +	Example usage::
> +
> +		## Read
> +		# cat /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state
> +		2
> +
> +		## Write
> +		# echo 2 > /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state
> +
> +What:           /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state_open
> +Date:           March 2026
> +KernelVersion:  7.0
> +Contact:        Steffen Trumtrar <kernel@pengutronix.de>
> +Description:
> +	Contains all LEDs and channels where an open condition was detected.

I'm also really confused by the cross-over here.

Are we documenting SPI behaviour or LED?

> +	The format is ledname:channel.
> +
> +	Example usage::
> +
> +		## Read
> +		# cat /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state_open
> +		rgb1:0 rgb2:4
> +
> +What:           /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state_short
> +Date:           March 2026
> +KernelVersion:  7.0
> +Contact:        Steffen Trumtrar <kernel@pengutronix.de>
> +Description:
> +	Contains all LEDs and channels where a short condition was detected.
> +	The format is ledname:channel.
> +
> +	Example usage::
> +
> +		## Read
> +		# cat /sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fault_state_short
> +		rgb1:0 rgb2:4
> 
> -- 
> 2.51.0
> 

-- 
Lee Jones [李琼斯]