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

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

Hi Oleh,

On 9/5/19 8:17 AM, Oleh Kravchenko wrote:
> 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.

It should reflect the kernel version in which the ABI is supposed to
appear.

>>> +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. 

Yes, I see now that we probably have a bug in repeat_store()
in drivers/leds/trigger/ledtrig-pattern.c.. It assumes that we have
already some pattern tuples defined and works properly only then.

It is not prepared for a case when we want to set repeat count
before defining the pattern and attempts to immediately start
pattern via pattern_trig_start_pattern(), which returns error
when no proper pattern is defined.

To fix that we could perhaps attempt to (re)start pattern in
repeat_store() only if data->npatterns > 0. It would be even
consequent with what we have there already few lines above
where led_cdev->pattern_clear(led_cdev) is guarded similarly.

>>
>> 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?

You're wasting them anyway due to alignment. If you really
cared about that you could add __packed modifier
to the struct definition but I don't think it makes
big difference in this case.

>>
>>> +
>>> +		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
> 

-- 
Best regards,
Jacek Anaszewski