Re: [PATCH v5 2/2] leds: add LED driver for EL15203000 board

[Jacek Anaszewski <jacek.anaszewski@gmail.com>]

Hi Oleh,

Thank you for the updated set.

Now it looks really good. Just few minor issues left.

And side note - please address the patches also to maintainers,
not only to the list.

On 8/31/19 12:46 AM, Oleh Kravchenko wrote:
> This patch adds a LED class driver for the RGB LEDs found on
> the Crane Merchandising System EL15203000 LEDs board
> (aka RED LEDs board).
> 
> Signed-off-by: Oleh Kravchenko <oleg@kaa.org.ua>
> ---
>  .../testing/sysfs-class-led-driver-el15203000 |  22 ++
>  drivers/leds/Kconfig                          |  13 +
>  drivers/leds/Makefile                         |   1 +
>  drivers/leds/leds-el15203000.c                | 362 ++++++++++++++++++
>  4 files changed, 398 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-led-driver-el15203000
>  create mode 100644 drivers/leds/leds-el15203000.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-led-driver-el15203000 b/Documentation/ABI/testing/sysfs-class-led-driver-el15203000
> new file mode 100644
> index 000000000000..767763409125
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-led-driver-el15203000
> @@ -0,0 +1,22 @@
> +What:		/sys/class/leds/<led>/hw_pattern
> +Date:		August 2019
> +KernelVersion:	5.3

Now it will be September and 5.5. It is late even for 5.4.

> +Description:
> +		Specify a hardware pattern for the EL15203000 LED.
> +		The LEDs board supports only predefined patterns by firmware
> +		for specific LEDs.
> +
> +		Breathing mode for Screen frame light tube:
> +		"0 4000 1 4000"
> +
> +		Cascade mode for Pipe LED:
> +		"1 800 2 800 4 800 8 800 16 800"
> +
> +		Inverted cascade mode for Pipe LED:
> +		"30 800 29 800 27 800 23 800 15 800"
> +
> +		Bounce mode for Pipe LED:
> +		"1 800 2 800 4 800 8 800 16 800 16 800 8 800 4 800 2 800 1 800"
> +
> +		Inverted bounce mode for Pipe LED:
> +		"30 800 29 800 27 800 23 800 15 800 15 800 23 800 27 800 29 800 30 800"
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 1988de1d64c0..6e7703fd03d0 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -132,6 +132,19 @@ config LEDS_CR0014114
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called leds-cr0014114.
>  
> +config LEDS_EL15203000
> +	tristate "LED Support for Crane EL15203000"
> +	depends on LEDS_CLASS
> +	depends on SPI
> +	depends on OF
> +	help
> +	  This option enables support for EL15203000 LED Board
> +	  (aka RED LED board) which is widely used in coffee vending
> +	  machines produced by Crane Merchandising Systems.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called leds-el15203000.
> +
>  config LEDS_LM3530
>  	tristate "LCD Backlight driver for LM3530"
>  	depends on LEDS_CLASS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 41fb073a39c1..2da39e896ce8 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -89,6 +89,7 @@ obj-$(CONFIG_LEDS_LM36274)		+= leds-lm36274.o
>  # LED SPI Drivers
>  obj-$(CONFIG_LEDS_CR0014114)		+= leds-cr0014114.o
>  obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
> +obj-$(CONFIG_LEDS_EL15203000)		+= leds-el15203000.o
>  
>  # LED Userspace Drivers
>  obj-$(CONFIG_LEDS_USER)			+= uleds.o
> diff --git a/drivers/leds/leds-el15203000.c b/drivers/leds/leds-el15203000.c
> new file mode 100644
> index 000000000000..9de81dee3618
> --- /dev/null
> +++ b/drivers/leds/leds-el15203000.c
> @@ -0,0 +1,362 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2019 Crane Merchandising Systems. All rights reserved.
> +// Copyright (C) 2019 Oleh Kravchenko <oleg@kaa.org.ua>
> +
> +#include <linux/delay.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/spi/spi.h>
> +
> +/*
> + * EL15203000 SPI protocol description:
> + * +-----+---------+
> + * | LED | COMMAND |
> + * +-----+---------+
> + * |  1  |    1    |
> + * +-----+---------+
> + * (*) LEDs MCU board expects 20 msec delay per byte.
> + *
> + * LEDs:
> + * +----------+--------------+-------------------------------------------+
> + * |    ID    |     NAME     |         DESCRIPTION                       |
> + * +----------+--------------+-------------------------------------------+
> + * | 'P' 0x50 |     Pipe     | Consists from 5 LEDs, controlled by board |
> + * +----------+--------------+-------------------------------------------+
> + * | 'S' 0x53 | Screen frame | Light tube around the screen              |
> + * +----------+--------------+-------------------------------------------+
> + * | 'V' 0x56 | Vending area | Highlights a cup of coffee                |
> + * +----------+--------------+-------------------------------------------+
> + *
> + * COMMAND:
> + * +----------+-----------------+--------------+--------------+
> + * |  VALUES  |       PIPE      | SCREEN FRAME | VENDING AREA |
> + * +----------+-----------------+--------------+--------------+
> + * | '0' 0x30 |                      Off                      |
> + * +----------+-----------------------------------------------+
> + * | '1' 0x31 |                      On                       |
> + * +----------+-----------------+--------------+--------------+
> + * | '2' 0x32 |     Cascade     |   Breathing  |
> + * +----------+-----------------+--------------+
> + * | '3' 0x33 | Inverse cascade |
> + * +----------+-----------------+
> + * | '4' 0x34 |     Bounce      |
> + * +----------+-----------------+
> + * | '5' 0x35 | Inverse bounce  |
> + * +----------+-----------------+
> + */
> +
> +/* EL15203000 default settings */
> +#define EL_FW_DELAY_USEC	20000ul
> +#define EL_PATTERN_DELAY_MSEC	800u
> +#define EL_PATTERN_LEN		10u
> +#define EL_PATTERN_HALF_LEN	(EL_PATTERN_LEN / 2)
> +
> +enum el15203000_command {
> +	/* for all LEDs */
> +	EL_OFF			= '0',
> +	EL_ON			= '1',
> +
> +	/* for Screen LED */
> +	EL_SCREEN_BREATHING	= '2',
> +
> +	/* for Pipe LED */
> +	EL_PIPE_CASCADE		= '2',
> +	EL_PIPE_INV_CASCADE	= '3',
> +	EL_PIPE_BOUNCE		= '4',
> +	EL_PIPE_INV_BOUNCE	= '5',
> +};
> +
> +struct el15203000_led {
> +	struct el15203000	*priv;
> +	struct led_classdev	ldev;
> +	u8			reg;
> +};
> +
> +struct el15203000 {
> +	struct device		*dev;
> +	struct mutex		lock;
> +	struct spi_device	*spi;
> +	unsigned long		delay;
> +	size_t			count;
> +	struct el15203000_led	leds[];
> +};
> +
> +static int el15203000_cmd(struct el15203000_led *led, u8 brightness)
> +{
> +	int		ret;
> +	u8		cmd[2];
> +	size_t		i;
> +
> +	mutex_lock(&led->priv->lock);
> +
> +	dev_dbg(led->priv->dev, "Set brightness of 0x%02x(%c) to 0x%02x(%c)",
> +		led->reg, led->reg, brightness, brightness);
> +
> +	/* to avoid SPI mistiming with firmware we should wait some time */
> +	if (time_after(led->priv->delay, jiffies)) {
> +		dev_dbg(led->priv->dev, "Wait %luus to sync",
> +			EL_FW_DELAY_USEC);
> +
> +		usleep_range(EL_FW_DELAY_USEC,
> +			     EL_FW_DELAY_USEC + 1);
> +	}
> +
> +	cmd[0] = led->reg;
> +	cmd[1] = brightness;
> +
> +	for (i = 0; i < ARRAY_SIZE(cmd); i++) {
> +		if (i)
> +			usleep_range(EL_FW_DELAY_USEC,
> +				     EL_FW_DELAY_USEC + 1);
> +
> +		ret = spi_write(led->priv->spi, &cmd[i], sizeof(cmd[i]));
> +		if (ret) {
> +			dev_err(led->priv->dev,
> +				"spi_write() error %d", ret);
> +			break;
> +		}
> +	}
> +
> +	led->priv->delay = jiffies + usecs_to_jiffies(EL_FW_DELAY_USEC);
> +
> +	mutex_unlock(&led->priv->lock);
> +
> +	return ret;
> +}
> +
> +static int el15203000_set_blocking(struct led_classdev *ldev,
> +				   enum led_brightness brightness)
> +{
> +	struct el15203000_led	*led = container_of(ldev,
> +						    struct el15203000_led,
> +						    ldev);
> +
> +	return el15203000_cmd(led, brightness == LED_OFF ? EL_OFF : EL_ON);
> +}
> +
> +static int el15203000_pattern_set_S(struct led_classdev *ldev,
> +				    struct led_pattern *pattern,
> +				    u32 len, int repeat)
> +{
> +	struct el15203000_led	*led = container_of(ldev,
> +						    struct el15203000_led,
> +						    ldev);
> +
> +	if (repeat > 0 || len != 2 ||
> +	    pattern[0].delta_t != 4000 || pattern[0].brightness != 0 ||
> +	    pattern[1].delta_t != 4000 || pattern[1].brightness != 1)
> +		return -EINVAL;
> +
> +	dev_dbg(led->priv->dev, "Breathing mode for 0x%02x(%c)",
> +		led->reg, led->reg);
> +
> +	return el15203000_cmd(led, EL_SCREEN_BREATHING);
> +}
> +
> +static bool is_cascade(const struct led_pattern *pattern, u32 len,
> +		       bool inv, bool right)
> +{
> +	int val, t;
> +	u32 i;
> +
> +	if (len != EL_PATTERN_HALF_LEN)
> +		return false;
> +
> +	val = right ? BIT(4) : BIT(0);
> +
> +	for (i = 0; i < len; i++) {
> +		t = inv ? ~val & GENMASK(4, 0) : val;
> +
> +		if (pattern[i].delta_t != EL_PATTERN_DELAY_MSEC ||
> +		    pattern[i].brightness != t)
> +			return false;
> +
> +		val = right ? val >> 1 : val << 1;
> +	}

Nice!

> +
> +	return true;
> +}
> +
> +static bool is_bounce(const struct led_pattern *pattern, u32 len, bool inv)
> +{
> +	if (len != EL_PATTERN_LEN)
> +		return false;
> +
> +	return is_cascade(pattern, EL_PATTERN_HALF_LEN, inv, false) &&
> +	       is_cascade(pattern +  EL_PATTERN_HALF_LEN,
> +			  EL_PATTERN_HALF_LEN, inv, true);
> +}
> +
> +static int el15203000_pattern_set_P(struct led_classdev *ldev,
> +				    struct led_pattern *pattern,
> +				    u32 len, int repeat)
> +{
> +	struct el15203000_led	*led = container_of(ldev,
> +						    struct el15203000_led,
> +						    ldev);
> +
> +	if (repeat > 0)

This is wrong. Repeat has to be -1 or > 0. If all patterns supported
by your device are infinite, then you should expect here -1.

Either way this needs to be covered in the ABI documentation too.

> +		return -EINVAL;
> +
> +	if (is_cascade(pattern, len, false, false)) {
> +		dev_dbg(led->priv->dev, "Cascade mode for 0x%02x(%c)",
> +			led->reg, led->reg);
> +
> +		return el15203000_cmd(led, EL_PIPE_CASCADE);
> +	} else if (is_cascade(pattern, len, true, false)) {
> +		dev_dbg(led->priv->dev, "Inverse cascade mode for 0x%02x(%c)",
> +			led->reg, led->reg);
> +
> +		return el15203000_cmd(led, EL_PIPE_INV_CASCADE);
> +	} else if (is_bounce(pattern, len, false)) {
> +		dev_dbg(led->priv->dev, "Bounce mode for 0x%02x(%c)",
> +			led->reg, led->reg);
> +
> +		return el15203000_cmd(led, EL_PIPE_BOUNCE);
> +	} else if (is_bounce(pattern, len, true)) {
> +		dev_dbg(led->priv->dev, "Inverse bounce mode for 0x%02x(%c)",
> +			led->reg, led->reg);
> +
> +		return el15203000_cmd(led, EL_PIPE_INV_BOUNCE);
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int el15203000_pattern_clear(struct led_classdev *ldev)
> +{
> +	struct el15203000_led	*led = container_of(ldev,
> +						    struct el15203000_led,
> +						    ldev);
> +
> +	return el15203000_cmd(led, EL_OFF);
> +}
> +
> +static int el15203000_probe_dt(struct el15203000 *priv)
> +{
> +	size_t			i = 0;
> +	struct el15203000_led	*led;
> +	struct fwnode_handle	*child;
> +	int			ret;
> +	u32			reg;
> +	struct led_init_data	init_data = {};
> +
> +	device_for_each_child_node(priv->dev, child) {

Please move above init_data initialization here.


> +		led = &priv->leds[i];

You can increment 'i' here, it is not used below and you will save one
LOC:

		led = &priv->leds[i++];

> +
> +		init_data.fwnode = child;

Please move it to where it will be needed. i.e. one line above
devm_led_classdev_register_ext().

> +
> +		ret = fwnode_property_read_u32(child, "reg", &reg);
> +		if (ret) {
> +			dev_err(priv->dev, "LED without ID number");
> +			fwnode_handle_put(child);
> +
> +			return ret;
> +		}
> +
> +		if (reg > U8_MAX) {
> +			dev_err(priv->dev, "LED value %d is invalid", reg);
> +			fwnode_handle_put(child);
> +
> +			return -EINVAL;
> +		}
> +
> +		led->reg = reg;

I'd just pass &led->reg directly to fwnode_property_read_u32().
Then you'll be able to drop local reg variable.

> +
> +		fwnode_property_read_string(child, "linux,default-trigger",
> +					    &led->ldev.default_trigger);
> +
> +		led->priv			  = priv;
> +		led->ldev.max_brightness	  = LED_ON;
> +		led->ldev.brightness_set_blocking = el15203000_set_blocking;
> +
> +		if (reg == 'S') {
> +			led->ldev.pattern_set	= el15203000_pattern_set_S;
> +			led->ldev.pattern_clear	= el15203000_pattern_clear;
> +		} else if (reg == 'P') {
> +			led->ldev.pattern_set	= el15203000_pattern_set_P;
> +			led->ldev.pattern_clear	= el15203000_pattern_clear;
> +		}
> +
> +		ret = devm_led_classdev_register_ext(priv->dev, &led->ldev,
> +						     &init_data);
> +		if (ret) {
> +			dev_err(priv->dev,
> +				"failed to register LED device %s, err %d",
> +				led->ldev.name, ret);
> +			fwnode_handle_put(child);
> +
> +			return ret;
> +		}
> +
> +		i++;
> +	}
> +
> +	return ret;
> +}
> +
> +static int el15203000_probe(struct spi_device *spi)
> +{
> +	struct el15203000	*priv;
> +	size_t			count;
> +	int			ret;
> +
> +	count = device_get_child_node_count(&spi->dev);
> +	if (!count) {
> +		dev_err(&spi->dev, "LEDs are not defined in device tree!");
> +		return -ENODEV;
> +	}
> +
> +	priv = devm_kzalloc(&spi->dev, struct_size(priv, leds, count),
> +			    GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	mutex_init(&priv->lock);
> +	priv->count	= count;
> +	priv->dev	= &spi->dev;
> +	priv->spi	= spi;
> +	priv->delay	= jiffies -
> +			  usecs_to_jiffies(EL_FW_DELAY_USEC);
> +
> +	ret = el15203000_probe_dt(priv);
> +	if (ret)
> +		return ret;
> +
> +	spi_set_drvdata(spi, priv);
> +
> +	return 0;
> +}
> +
> +static int el15203000_remove(struct spi_device *spi)
> +{
> +	struct el15203000 *priv = spi_get_drvdata(spi);
> +
> +	mutex_destroy(&priv->lock);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id el15203000_dt_ids[] = {
> +	{ .compatible = "crane,el15203000", },
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(of, el15203000_dt_ids);
> +
> +static struct spi_driver el15203000_driver = {
> +	.probe		= el15203000_probe,
> +	.remove		= el15203000_remove,
> +	.driver = {
> +		.name		= KBUILD_MODNAME,
> +		.of_match_table	= el15203000_dt_ids,
> +	},
> +};
> +
> +module_spi_driver(el15203000_driver);
> +
> +MODULE_AUTHOR("Oleh Kravchenko <oleg@kaa.org.ua>");
> +MODULE_DESCRIPTION("el15203000 LED driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("spi:el15203000");
> 

-- 
Best regards,
Jacek Anaszewski