[PATCH v4 1/2] dt-bindings: leds: Add binding for spi-byte LED.

[PATCH v4 1/2] dt-bindings: leds: Add binding for spi-byte LED.

[oss]

From: Christian Mauderer <oss@c-mauderer.de>

This patch adds the binding documentation for a simple SPI based LED
controller which use only one byte for setting the brightness.

Signed-off-by: Christian Mauderer <oss@c-mauderer.de>
---

Changes compared to v3:
- rename binding to ubnt,acb-spi-led
- rewrite description to fit the new binding
- remove off-value and max-value - now determined depending on the compatible
  string
- add 'default-state'

Changes compared to v2:
- None

Changes compared to v1:
- rename ubnt-spi to leds-spi-byte
- rename "ubnt-spi,off_bright" and "ubnt-spi,max_bright" to
  "leds-spi-byte,off-value" and "leds-spi-byte,max-value" and mark them required
- rename led-controller node to "led-controller"
- extend description
- remove SPI controller
- use "white:status" for the example label

 .../bindings/leds/leds-spi-byte.txt           | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-spi-byte.txt

diff --git a/Documentation/devicetree/bindings/leds/leds-spi-byte.txt b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
new file mode 100644
index 000000000000..28b6b2d9091e
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
@@ -0,0 +1,44 @@
+* Single Byte SPI LED Device Driver.
+
+The driver can be used for controllers with a very simple SPI protocol:
+- one LED is controlled by a single byte on MOSI
+- the value of the byte gives the brightness between two values (lowest to
+  highest)
+- no return value is necessary (no MISO signal)
+
+The value for lowest and highest brightness is dependent on the device and
+therefore on the compatible string.
+
+Depending on the compatible string some special functions (like hardware
+accelerated blinking) might can be supported too.
+
+The driver currently only supports one LED. The properties of the LED are
+configured in a sub-node in the device node.
+
+Required properties:
+- compatible: should be one of
+   * "ubnt,acb-spi-led"		microcontroller (SONiX 8F26E611LA) based device
+				used for example in Ubiquiti airCube ISP
+
+Property rules described in Documentation/devicetree/bindings/spi/spi-bus.txt
+apply.
+
+LED sub-node properties:
+- label:
+	see Documentation/devicetree/bindings/leds/common.txt
+- default-state:
+	see Documentation/devicetree/bindings/leds/common.txt
+	Only "on" and "off" are supported.
+
+Example:
+
+led-controller@0 {
+	compatible = "ubnt,acb-spi-led";
+	reg = <0>;
+	spi-max-frequency = <100000>;
+
+	led {
+		label = "white:status";
+		default-state = "on";
+	};
+};
-- 
2.21.0

[PATCH v4 2/2] leds: spi-byte: add single byte SPI LED driver

[oss]

From: Christian Mauderer <oss@c-mauderer.de>

This driver adds support for simple SPI based LED controller which use
only one byte for setting the brightness.

Signed-off-by: Christian Mauderer <oss@c-mauderer.de>
---

Changes compared to v3:
- remove led_classdev_unregister - not longer necessary due to
  devm_led_classdev_register
- move off_value and max_value to chipdef structure
- reduce intermediate local variables during open firmware parsing
- destroy mutex if devm_led_classdev_register went wrong
- add 'default-state'

Changes compared to v2:
- use "if (ret)" instead of "if (ret != 0)"
- don't initialize ldev-fields with zero
- use devm_led_classdev_register instead of led_classdev_register
- check for error instead of good case with the last if in spi_byte_probe

Changes compared to v1:
- rename ubnt-spi to leds-spi-byte
- rework probe to get all parameters before allocating anything -> error checks
  all collected together and initializing all fields of the device structure is
  more obvious
- fix some unsteady indentations during variable declaration
- rework comment with protocol explanation
- handle case of off_bright > max_bright
- fix spelling in commit message
- mutex_destroy in remove
- change label to use either use the given one without a prefix or a default one

 drivers/leds/Kconfig         |  10 +++
 drivers/leds/Makefile        |   1 +
 drivers/leds/leds-spi-byte.c | 161 +++++++++++++++++++++++++++++++++++
 3 files changed, 172 insertions(+)
 create mode 100644 drivers/leds/leds-spi-byte.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index a72f97fca57b..b6235e7e1482 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -766,6 +766,16 @@ config LEDS_NIC78BX
 	  To compile this driver as a module, choose M here: the module
 	  will be called leds-nic78bx.
 
+config LEDS_SPI_BYTE
+	tristate "LED support for SPI LED controller with a single byte"
+	depends on LEDS_CLASS
+	depends on SPI
+	depends on OF
+	help
+	  This option enables support for LED controller which use a single byte
+	  for controlling the brightness. Currently the following controller is
+	  supported: Ubiquiti airCube ISP microcontroller based LED controller.
+
 comment "LED Triggers"
 source "drivers/leds/trigger/Kconfig"
 
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 4c1b0054f379..1786d7e2c236 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -75,6 +75,7 @@ obj-$(CONFIG_LEDS_PM8058)		+= leds-pm8058.o
 obj-$(CONFIG_LEDS_MLXCPLD)		+= leds-mlxcpld.o
 obj-$(CONFIG_LEDS_MLXREG)		+= leds-mlxreg.o
 obj-$(CONFIG_LEDS_NIC78BX)		+= leds-nic78bx.o
+obj-$(CONFIG_LEDS_SPI_BYTE)		+= leds-spi-byte.o
 obj-$(CONFIG_LEDS_MT6323)		+= leds-mt6323.o
 obj-$(CONFIG_LEDS_LM3692X)		+= leds-lm3692x.o
 obj-$(CONFIG_LEDS_SC27XX_BLTC)		+= leds-sc27xx-bltc.o
diff --git a/drivers/leds/leds-spi-byte.c b/drivers/leds/leds-spi-byte.c
new file mode 100644
index 000000000000..b231b563b7bb
--- /dev/null
+++ b/drivers/leds/leds-spi-byte.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Christian Mauderer <oss@c-mauderer.de>
+
+/*
+ * The driver supports controllers with a very simple SPI protocol:
+ * - one LED is controlled by a single byte on MOSI
+ * - the value of the byte gives the brightness between two values (lowest to
+ *   highest)
+ * - no return value is necessary (no MISO signal)
+ *
+ * The value for minimum and maximum brightness depends on the device
+ * (compatible string).
+ *
+ * Supported devices:
+ * - "ubnt,acb-spi-led": Microcontroller (SONiX 8F26E611LA) based device used
+ *   for example in Ubiquiti airCube ISP. Reverse engineered protocol for this
+ *   controller:
+ *   * Higher two bits set a mode. Lower six bits are a parameter.
+ *   * Mode: 00 -> set brightness between 0x00 (min) and 0x3F (max)
+ *   * Mode: 01 -> pulsing pattern (min -> max -> min) with an interval. From
+ *     some tests, the period is about (50ms + 102ms * parameter). There is a
+ *     slightly different pattern starting from 0x10 (longer gap between the
+ *     pulses) but the time still follows that calculation.
+ *   * Mode: 10 -> same as 01 but with only a ramp from min to max. Again a
+ *     slight jump in the pattern at 0x10.
+ *   * Mode: 11 -> blinking (off -> 25% -> off -> 25% -> ...) with a period of
+ *     (105ms * parameter)
+ *   NOTE: This driver currently only supports mode 00.
+ */
+
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+#include <linux/mutex.h>
+#include <uapi/linux/uleds.h>
+
+struct spi_byte_chipdef {
+	/* SPI byte that will be send to switch the LED off */
+	u8	off_value;
+	/* SPI byte that will be send to switch the LED to maximum brightness */
+	u8	max_value;
+};
+
+struct spi_byte_led {
+	struct led_classdev		ldev;
+	struct spi_device		*spi;
+	char				name[LED_MAX_NAME_SIZE];
+	struct mutex			mutex;
+	const struct spi_byte_chipdef	*cdef;
+};
+
+static const struct spi_byte_chipdef ubnt_acb_spi_led_cdef = {
+	.off_value = 0x0,
+	.max_value = 0x3F,
+};
+
+static const struct of_device_id spi_byte_dt_ids[] = {
+	{ .compatible = "ubnt,acb-spi-led", .data = &ubnt_acb_spi_led_cdef },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, spi_byte_dt_ids);
+
+static int spi_byte_brightness_set_blocking(struct led_classdev *dev,
+					    enum led_brightness brightness)
+{
+	struct spi_byte_led *led = container_of(dev, struct spi_byte_led, ldev);
+	u8 value;
+	int ret;
+
+	value = (u8) brightness + led->cdef->off_value;
+
+	mutex_lock(&led->mutex);
+	ret = spi_write(led->spi, &value, sizeof(value));
+	mutex_unlock(&led->mutex);
+
+	return ret;
+}
+
+static int spi_byte_probe(struct spi_device *spi)
+{
+	const struct of_device_id *of_dev_id;
+	struct device_node *child;
+	struct device *dev = &spi->dev;
+	struct spi_byte_led *led;
+	const char *name = "leds-spi-byte::";
+	const char *state;
+	int ret;
+
+	of_dev_id = of_match_device(spi_byte_dt_ids, dev);
+	if (!of_dev_id)
+		return -EINVAL;
+
+	if (of_get_child_count(dev->of_node) != 1) {
+		dev_err(dev, "Device must have exactly one LED sub-node.");
+		return -EINVAL;
+	}
+	child = of_get_next_child(dev->of_node, NULL);
+
+	led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
+	if (!led)
+		return -ENOMEM;
+
+	of_property_read_string(child, "label", &name);
+	strlcpy(led->name, name, sizeof(led->name));
+	led->spi = spi;
+	mutex_init(&led->mutex);
+	led->cdef = of_dev_id->data;
+	led->ldev.name = led->name;
+	led->ldev.brightness = LED_OFF;
+	led->ldev.max_brightness = led->cdef->max_value - led->cdef->off_value;
+	led->ldev.brightness_set_blocking = spi_byte_brightness_set_blocking;
+
+	state = of_get_property(child, "default-state", NULL);
+	if (state) {
+		if (!strcmp(state, "on")) {
+			led->ldev.brightness = led->ldev.max_brightness;
+		} else if (strcmp(state, "off")) {
+			/* all other cases except "off" */
+			dev_err(dev, "default-state can only be 'on' or 'off'");
+			return -EINVAL;
+		}
+	}
+	spi_byte_brightness_set_blocking(&led->ldev,
+					 led->ldev.brightness);
+
+	ret = devm_led_classdev_register(&spi->dev, &led->ldev);
+	if (ret) {
+		mutex_destroy(&led->mutex);
+		return ret;
+	}
+	spi_set_drvdata(spi, led);
+
+	return 0;
+}
+
+static int spi_byte_remove(struct spi_device *spi)
+{
+	struct spi_byte_led	*led = spi_get_drvdata(spi);
+
+	mutex_destroy(&led->mutex);
+
+	return 0;
+}
+
+static struct spi_driver spi_byte_driver = {
+	.probe		= spi_byte_probe,
+	.remove		= spi_byte_remove,
+	.driver = {
+		.name		= KBUILD_MODNAME,
+		.of_match_table	= spi_byte_dt_ids,
+	},
+};
+
+module_spi_driver(spi_byte_driver);
+
+MODULE_AUTHOR("Christian Mauderer <oss@c-mauderer.de>");
+MODULE_DESCRIPTION("single byte SPI LED driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("spi:leds-spi-byte");
-- 
2.21.0

Re: [PATCH v4 1/2] dt-bindings: leds: Add binding for spi-byte LED.

[Rob Herring]

On Mon, 13 May 2019 21:33:06 +0200, oss@c-mauderer.de wrote:
> From: Christian Mauderer <oss@c-mauderer.de>
> 
> This patch adds the binding documentation for a simple SPI based LED
> controller which use only one byte for setting the brightness.
> 
> Signed-off-by: Christian Mauderer <oss@c-mauderer.de>
> ---
> 
> Changes compared to v3:
> - rename binding to ubnt,acb-spi-led
> - rewrite description to fit the new binding
> - remove off-value and max-value - now determined depending on the compatible
>   string
> - add 'default-state'
> 
> Changes compared to v2:
> - None
> 
> Changes compared to v1:
> - rename ubnt-spi to leds-spi-byte
> - rename "ubnt-spi,off_bright" and "ubnt-spi,max_bright" to
>   "leds-spi-byte,off-value" and "leds-spi-byte,max-value" and mark them required
> - rename led-controller node to "led-controller"
> - extend description
> - remove SPI controller
> - use "white:status" for the example label
> 
>  .../bindings/leds/leds-spi-byte.txt           | 44 +++++++++++++++++++
>  1 file changed, 44 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/leds-spi-byte.txt
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v4 1/2] dt-bindings: leds: Add binding for spi-byte LED.

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 1275 bytes --]

Hi!

> From: Christian Mauderer <oss@c-mauderer.de>
> 
> This patch adds the binding documentation for a simple SPI based LED
> controller which use only one byte for setting the brightness.
> 
> Signed-off-by: Christian Mauderer <oss@c-mauderer.de>
> ---

> diff --git a/Documentation/devicetree/bindings/leds/leds-spi-byte.txt b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
> new file mode 100644
> index 000000000000..28b6b2d9091e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
> @@ -0,0 +1,44 @@
> +* Single Byte SPI LED Device Driver.

> +The driver can be used for controllers with a very simple SPI protocol:
> +- one LED is controlled by a single byte on MOSI
> +- the value of the byte gives the brightness between two values (lowest to
> +  highest)
> +- no return value is necessary (no MISO signal)

I'd expect this file to be named acb-spi-led.txt, or something, and
talk about that u-controller, not its device driver -- as devicetree
binding describes hardware, not driver.

But you already have an ack from rob, so...
									Pavel
									
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: [PATCH v4 2/2] leds: spi-byte: add single byte SPI LED driver

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 468 bytes --]

On Mon 2019-05-13 21:33:07, oss@c-mauderer.de wrote:
> From: Christian Mauderer <oss@c-mauderer.de>
> 
> This driver adds support for simple SPI based LED controller which use
> only one byte for setting the brightness.
> 
> Signed-off-by: Christian Mauderer <oss@c-mauderer.de>

Acked-by: Pavel Machek <pavel@ucw.cz>

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: [PATCH v4 1/2] dt-bindings: leds: Add binding for spi-byte LED.

[Christian Mauderer]

On 19/05/2019 23:25, Pavel Machek wrote:
> Hi!
> 
>> From: Christian Mauderer <oss@c-mauderer.de>
>>
>> This patch adds the binding documentation for a simple SPI based LED
>> controller which use only one byte for setting the brightness.
>>
>> Signed-off-by: Christian Mauderer <oss@c-mauderer.de>
>> ---
> 
>> diff --git a/Documentation/devicetree/bindings/leds/leds-spi-byte.txt b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
>> new file mode 100644
>> index 000000000000..28b6b2d9091e
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
>> @@ -0,0 +1,44 @@
>> +* Single Byte SPI LED Device Driver.
> 
>> +The driver can be used for controllers with a very simple SPI protocol:
>> +- one LED is controlled by a single byte on MOSI
>> +- the value of the byte gives the brightness between two values (lowest to
>> +  highest)
>> +- no return value is necessary (no MISO signal)
> 
> I'd expect this file to be named acb-spi-led.txt, or something, and
> talk about that u-controller, not its device driver -- as devicetree
> binding describes hardware, not driver.
> 
> But you already have an ack from rob, so...
> 									Pavel
> 									

So basically it would have been better to move the description that I
added to the c-file as "supported devices" in the device tree file?

With both commits already acked: Rob and Pavel: Should I change that?

If you both say yes, I would rename the file in the binding like
suggested and move the detailed protocol description from the driver to
the binding.

Best regards

Christian

Re: [PATCH v4 1/2] dt-bindings: leds: Add binding for spi-byte LED.

[Jacek Anaszewski]

Hi Christian,

On 5/20/19 7:19 PM, Christian Mauderer wrote:
> On 19/05/2019 23:25, Pavel Machek wrote:
>> Hi!
>>
>>> From: Christian Mauderer <oss@c-mauderer.de>
>>>
>>> This patch adds the binding documentation for a simple SPI based LED
>>> controller which use only one byte for setting the brightness.
>>>
>>> Signed-off-by: Christian Mauderer <oss@c-mauderer.de>
>>> ---
>>
>>> diff --git a/Documentation/devicetree/bindings/leds/leds-spi-byte.txt b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
>>> new file mode 100644
>>> index 000000000000..28b6b2d9091e
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
>>> @@ -0,0 +1,44 @@
>>> +* Single Byte SPI LED Device Driver.
>>
>>> +The driver can be used for controllers with a very simple SPI protocol:
>>> +- one LED is controlled by a single byte on MOSI
>>> +- the value of the byte gives the brightness between two values (lowest to
>>> +  highest)
>>> +- no return value is necessary (no MISO signal)
>>
>> I'd expect this file to be named acb-spi-led.txt, or something, and
>> talk about that u-controller, not its device driver -- as devicetree
>> binding describes hardware, not driver.
>>
>> But you already have an ack from rob, so...
>> 									Pavel
>> 									
> 
> So basically it would have been better to move the description that I
> added to the c-file as "supported devices" in the device tree file?
> 
> With both commits already acked: Rob and Pavel: Should I change that?
> 
> If you both say yes, I would rename the file in the binding like
> suggested and move the detailed protocol description from the driver to
> the binding.

Let's not ramble on it. It is good as is.

Patch set applied to the for-next branch of linux-leds.git.

Thank you for your work.

-- 
Best regards,
Jacek Anaszewski

Re: [PATCH v4 1/2] dt-bindings: leds: Add binding for spi-byte LED.

[Christian Mauderer]

Hello Jacek, Pavel, Rob, Dan and everyone who I might have missed,

thanks for the great feedback, the patience while reviewing my patches
and for accepting it.

Although it needed a longer discussion than I expected (partially due to
my rush creating new versions at the beginning) it was a quite positive
experience and I'm quite ready to repeat it if some other opportunity
arises.

Best regards

Christian

On 20/05/2019 22:15, Jacek Anaszewski wrote:
> Hi Christian,
> 
> On 5/20/19 7:19 PM, Christian Mauderer wrote:
>> On 19/05/2019 23:25, Pavel Machek wrote:
>>> Hi!
>>>
>>>> From: Christian Mauderer <oss@c-mauderer.de>
>>>>
>>>> This patch adds the binding documentation for a simple SPI based LED
>>>> controller which use only one byte for setting the brightness.
>>>>
>>>> Signed-off-by: Christian Mauderer <oss@c-mauderer.de>
>>>> ---
>>>
>>>> diff --git
>>>> a/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
>>>> b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
>>>> new file mode 100644
>>>> index 000000000000..28b6b2d9091e
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/leds/leds-spi-byte.txt
>>>> @@ -0,0 +1,44 @@
>>>> +* Single Byte SPI LED Device Driver.
>>>
>>>> +The driver can be used for controllers with a very simple SPI
>>>> protocol:
>>>> +- one LED is controlled by a single byte on MOSI
>>>> +- the value of the byte gives the brightness between two values
>>>> (lowest to
>>>> +� highest)
>>>> +- no return value is necessary (no MISO signal)
>>>
>>> I'd expect this file to be named acb-spi-led.txt, or something, and
>>> talk about that u-controller, not its device driver -- as devicetree
>>> binding describes hardware, not driver.
>>>
>>> But you already have an ack from rob, so...
>>> ����������������������������������� Pavel
>>> �����������������������������������
>>
>> So basically it would have been better to move the description that I
>> added to the c-file as "supported devices" in the device tree file?
>>
>> With both commits already acked: Rob and Pavel: Should I change that?
>>
>> If you both say yes, I would rename the file in the binding like
>> suggested and move the detailed protocol description from the driver to
>> the binding.
> 
> Let's not ramble on it. It is good as is.
> 
> Patch set applied to the for-next branch of linux-leds.git.
> 
> Thank you for your work.
>