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Subject: Re: [PATCH v5 2/2] leds: add LED driver for EL15203000 board
From:   Oleh Kravchenko <oleg@kaa.org.ua>
In-Reply-To: <371b2ecd-034d-dd64-d47b-b7fcc99bedba@gmail.com>
Date:   Thu, 5 Sep 2019 09:17:53 +0300
Cc:     devicetree@vger.kernel.org, linux-leds@vger.kernel.org
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References: <20190830224619.15728-1-oleg@kaa.org.ua>
 <20190830224619.15728-2-oleg@kaa.org.ua>
 <371b2ecd-034d-dd64-d47b-b7fcc99bedba@gmail.com>
To:     Jacek Anaszewski <jacek.anaszewski@gmail.com>
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Hello Jacek,
Few question from my side just for better understanding :)

> 5 вер. 2019 р. о 12:23 дп Jacek Anaszewski <jacek.anaszewski@gmail.com> написав(ла):
> 
> 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.

Here should month of patch creation or when it will be reviewed? :)
Because I sent in 31 August.

> 
>> +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.

Ok, then we have bug in led pattern trigger.
echo -1 > /…/repeat doesn’t work as expected and return error.
So if I tried to change repeat from sysfs, it will never be -1 again. 

> 
> 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.

No problem.

> 
> 
>> +		led = &priv->leds[i];
> 
> You can increment 'i' here, it is not used below and you will save one
> LOC:
> 
> 		led = &priv->leds[i++];

Agree.

> 
>> +
>> +		init_data.fwnode = child;
> 
> Please move it to where it will be needed. i.e. one line above
> devm_led_classdev_register_ext().

Will do.

> 
>> +
>> +		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.

For this device/driver reg value is just one byte
You are ok to waste 3 bytes for every EL15203000 LED?

> 
>> +
>> +		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