[Letux-kernel] [PATCH] drivers: led: is31fl319x: 6/9-channel light effect led driver

Jacek Anaszewski j.anaszewski at samsung.com
Tue Apr 19 11:14:23 CEST 2016


Hi Nikolaus,

Thanks for the patch. Please refer to my remarks in the code.

On 04/18/2016 08:43 PM, H. Nikolaus Schaller wrote:
> This is a driver for the Integrated Silicon Solution Inc. LED driver
> chips IS31FL3196 and IS31FL3199. They can drive up to 6 or 9
> LEDs.
>
> Each LED is individually controllable in brightness (through pwm)
> in 256 steps so that RGB LEDs can show any of ca. 16 Mio colors.
>
> The maximum current of the LEDs can be programmed and limited to
> 5 .. 40mA through a device tree property.
>
> The chip is connected through I2C and can have one of 4 addresses (0x64 .. 0x67)
> depending on how the AD pin is connected. The address is defined by the
> reg property as usual.
>
> The chip also has a shutdown input which could be connected to a GPIO,
> but this driver uses software shutdown if all LEDs are inactivated.
>
> The chip also has breathing and audio features which are not supported
> by this driver.
>
> This driver was developed and tested on OMAP5 based Pyra handheld prototype.
>
> Signed-off-by: H. Nikolaus Schaller <hns at goldelico.com>
> ---
>   .../devicetree/bindings/leds/is31fl319x.txt        |  41 +++
>   drivers/leds/Kconfig                               |   8 +
>   drivers/leds/Makefile                              |   1 +
>   drivers/leds/leds-is31fl319x.c                     | 406 +++++++++++++++++++++
>   include/linux/leds-is31fl319x.h                    |  24 ++
>   5 files changed, 480 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/leds/is31fl319x.txt
>   create mode 100644 drivers/leds/leds-is31fl319x.c
>   create mode 100644 include/linux/leds-is31fl319x.h
>
> diff --git a/Documentation/devicetree/bindings/leds/is31fl319x.txt b/Documentation/devicetree/bindings/leds/is31fl319x.txt
> new file mode 100644
> index 0000000..d13c7ca
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/is31fl319x.txt
> @@ -0,0 +1,41 @@
> +LEDs connected to is31fl319x RGB LED controller chip
> +
> +Required properties:
> +- compatible : should be : "issi,is31fl3196" or "issi,is31fl3199".

s/should be :/Should be/

> +- #address-cells: must be 1
> +- #size-cells: must be 0

s/must/Must/

Please begin the property description with a capital letter,
and also end it with a dot.
This remark applies also to the other properties.

> +- reg: 0x64, 0x65, 0x66, 0x67.
> +
> +Optional properties:
> +- max-current-ma:	maximum led current (5..40 mA, default 20 mA)

There is leds-max-microamp property for this -
see Documentation/devicetree/bindings/leds/common.txt.
I'd rephrase this as follows:

- led-max-microamp: See Documentation/devicetree/bindings/leds/common.txt.
         Valid values: 50000 - 400000, step by (?) (rounded {up|down})
         Default: 20000

> +- audio-gain-db:	audio gain selection (0..21 dB. default 0 dB)

Please follow the aforementioned "Valid values" pattern.
It would also be nice to have more informative description on the
purpose of this property.

> +- breathing & audio:	not implemented

There is no point in documenting unused properties.

> +
> +Each led is represented as a sub-node of the issi,is31fl319x device.
> +
> +LED sub-node properties:
> +- label : (optional) see Documentation/devicetree/bindings/leds/common.txt
> +- reg : number of LED line (0 to 5 or 0 to 8 - not all need to be present)
> +- linux,default-trigger : (optional)
> +   see Documentation/devicetree/bindings/leds/common.txt
> +
> +Examples:
> +
> +fancy_leds: is31fl3196 at 65 {
> +	compatible = "issi,is31fl319x";
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +	reg = <0x65>;
> +
> +	led0: red-aux at 0 {
> +		label = "red:aux";
> +		reg = <0>;
> +	};
> +
> +	led1: green-power at 4 {
> +		label = "green:power";
> +		reg = <4>;
> +		linux,default-trigger = "default-on";
> +	};
> +};

Generally I prefer to have DT bindings documentation in a separate
patch.

> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 2251478..f099bcb 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -491,6 +491,14 @@ config LEDS_ASIC3
>   	  cannot be used. This driver supports hardware blinking with an on+off
>   	  period from 62ms to 125s. Say Y to enable LEDs on the HP iPAQ hx4700.
>
> +config LEDS_IS31FL319X
> +	tristate "LED Support for IS31FL319x I2C chip"
> +	depends on LEDS_CLASS && I2C
> +	help
> +	  This option enables support for LEDs connected to IS31FL3196
> +	  or IS31FL3199 LED driver chips accessed via the I2C bus.
> +	  Driver support brightness control and hardware-assisted blinking.
> +
>   config LEDS_TCA6507
>   	tristate "LED Support for TCA6507 I2C chip"
>   	depends on LEDS_CLASS && I2C
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index cb2013d..eee3010 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_LEDS_TCA6507)		+= leds-tca6507.o
>   obj-$(CONFIG_LEDS_TLC591XX)		+= leds-tlc591xx.o
>   obj-$(CONFIG_LEDS_CLEVO_MAIL)		+= leds-clevo-mail.o
>   obj-$(CONFIG_LEDS_IPAQ_MICRO)		+= leds-ipaq-micro.o
> +obj-$(CONFIG_LEDS_IS31FL319X)		+= leds-is31fl319x.o
>   obj-$(CONFIG_LEDS_HP6XX)		+= leds-hp6xx.o
>   obj-$(CONFIG_LEDS_OT200)		+= leds-ot200.o
>   obj-$(CONFIG_LEDS_FSG)			+= leds-fsg.o
> diff --git a/drivers/leds/leds-is31fl319x.c b/drivers/leds/leds-is31fl319x.c
> new file mode 100644
> index 0000000..e211c46
> --- /dev/null
> +++ b/drivers/leds/leds-is31fl319x.c
> @@ -0,0 +1,406 @@
> +/*
> + * Copyright 2015 Golden Delcious Computers
> + *
> + * Author: Nikolaus Schaller <hns at goldelico.com>
> + *
> + * Based on leds-tca6507.c
> + *
> + * This file is subject to the terms and conditions of version 2 of
> + * the GNU General Public License.  See the file COPYING in the main
> + * directory of this archive for more details.
> + *
> + * LED driver for the IS31FL3196/99 to drive 6 or 9 light effect LEDs.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/leds.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/workqueue.h>
> +#include <linux/leds-is31fl319x.h>
> +#include <linux/of.h>

Please keep include directives in an alphabetical order.

> +
> +/* register numbers */
> +#define IS31FL319X_SHUTDOWN	0x00
> +#define IS31FL319X_CTRL1	0x01
> +#define IS31FL319X_CTRL2	0x02
> +#define IS31FL319X_CONFIG1	0x03
> +#define IS31FL319X_CONFIG2	0x04
> +#define IS31FL319X_RAMP_MODE	0x05
> +#define IS31FL319X_BREATH_MASK	0x06
> +#define IS31FL319X_PWM1		0x07
> +#define IS31FL319X_PWM2		0x08
> +#define IS31FL319X_PWM3		0x09
> +#define IS31FL319X_PWM4		0x0a
> +#define IS31FL319X_PWM5		0x0b
> +#define IS31FL319X_PWM6		0x0c
> +#define IS31FL319X_PWM7		0x0d
> +#define IS31FL319X_PWM8		0x0e
> +#define IS31FL319X_PWM9		0x0f
> +#define IS31FL319X_DATA_UPDATE	0x10
> +#define IS31FL319X_T0_1		0x11
> +#define IS31FL319X_T0_2		0x12
> +#define IS31FL319X_T0_3		0x13
> +#define IS31FL319X_T0_4		0x14
> +#define IS31FL319X_T0_5		0x15
> +#define IS31FL319X_T0_6		0x16
> +#define IS31FL319X_T0_7		0x17
> +#define IS31FL319X_T0_8		0x18
> +#define IS31FL319X_T0_9		0x19
> +#define IS31FL319X_T123_1	0x1a
> +#define IS31FL319X_T123_2	0x1b
> +#define IS31FL319X_T123_3	0x1c
> +#define IS31FL319X_T4_1		0x1d
> +#define IS31FL319X_T4_2		0x1e
> +#define IS31FL319X_T4_3		0x1f
> +#define IS31FL319X_T4_4		0x20
> +#define IS31FL319X_T4_5		0x21
> +#define IS31FL319X_T4_6		0x22
> +#define IS31FL319X_T4_7		0x23
> +#define IS31FL319X_T4_8		0x24
> +#define IS31FL319X_T4_9		0x25
> +#define IS31FL319X_TIME_UPDATE	0x26
> +
> +#define	IS31FL319X_REG_CNT	(IS31FL319X_TIME_UPDATE + 1)
> +
> +#define NUM_LEDS 9	/* max for 3199 chip */
> +
> +struct is31fl319x_chip {
> +	struct i2c_client	*client;
> +	struct work_struct	work;
> +	bool			work_scheduled;
> +	spinlock_t		lock;
> +	u8			reg_file[IS31FL319X_REG_CNT];
> +
> +	struct is31fl319x_led {
> +		struct is31fl319x_chip	*chip;
> +		struct led_classdev	led_cdev;
> +	} leds[NUM_LEDS];
> +};
> +
> +static const struct i2c_device_id is31fl319x_id[] = {
> +	{ "is31fl3196", 6 },
> +	{ "is31fl3196", 9 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, is31fl319x_id);
> +
> +
> +static int is31fl319x_write(struct is31fl319x_chip *is31, u8 reg, u8 byte)
> +{
> +	struct i2c_client *cl = is31->client;
> +
> +	if (reg >= IS31FL319X_REG_CNT)
> +		return -EIO;
> +	is31->reg_file[reg] = byte;	/* save in cache */
> +	dev_dbg(&is31->client->dev, "write %02x to reg %02x\n", byte, reg);
> +	return i2c_smbus_write_byte_data(cl, reg, byte);
> +}
> +
> +static int is31fl319x_read(struct is31fl319x_chip *is31, u8 reg)
> +{
> +	if (reg >= IS31FL319X_REG_CNT)
> +		return -EIO;
> +	return is31->reg_file[reg];	/* read crom cache (can't read chip) */
> +}
> +
> +static void is31fl319x_work(struct work_struct *work)
> +{
> +	struct is31fl319x_chip *is31 = container_of(work,
> +						    struct is31fl319x_chip,
> +						    work);
> +	unsigned long flags;
> +	int i;
> +	u8 ctrl1, ctrl2;
> +
> +	dev_dbg(&is31->client->dev, "work called\n");
> +
> +	spin_lock_irqsave(&is31->lock, flags);
> +	/* make subsequent changes run another schedule_work */
> +	is31->work_scheduled = false;
> +	spin_unlock_irqrestore(&is31->lock, flags);
> +
> +	dev_dbg(&is31->client->dev, "write to chip\n");
> +
> +	ctrl1 = 0;
> +	ctrl2 = 0;
> +
> +	for (i = 0; i < NUM_LEDS; i++) {
> +		struct led_classdev *led = &is31->leds[i].led_cdev;
> +		bool on;
> +
> +		if (!is31->leds[i].led_cdev.name)
> +			continue;
> +
> +		dev_dbg(&is31->client->dev, "set brightness %u for led %u\n",
> +					    led->brightness, i);
> +
> +		/* update brightness register */
> +		is31fl319x_write(is31, IS31FL319X_PWM1 + i, led->brightness);
> +
> +		/* update output enable bits */
> +		on = led->brightness > LED_OFF;

It's more common to achieve the same in the following way:

                 on = !!led->brightness;

> +		if (i < 3)
> +			ctrl1 |= on << i;	/* 0..2 => bit 0..2 */
> +		else if (i < 6)
> +			ctrl1 |= on << (i+1);	/* 3..5 => bit 4..6 */
> +		else
> +			ctrl2 |= on << (i-6);	/* 6..8 => bit 0..2 */
> +	}

Why are you iterating over all sub-LEDs? One LED class device should
control single sub-LED/iout.

> +
> +	/* check if any PWM is enabled or all outputs are now off */
> +	if (ctrl1 > 0 || ctrl2 > 0) {
> +		dev_dbg(&is31->client->dev, "power up\n");
> +		is31fl319x_write(is31, IS31FL319X_CTRL1, ctrl1);
> +		is31fl319x_write(is31, IS31FL319X_CTRL2, ctrl2);
> +		/* update PWMs */
> +		is31fl319x_write(is31, IS31FL319X_DATA_UPDATE, 0x00);
> +		/* enable chip from shut down */
> +		is31fl319x_write(is31, IS31FL319X_SHUTDOWN, 0x01);
> +	} else {
> +		dev_dbg(&is31->client->dev, "power down\n");
> +		/* shut down */
> +		is31fl319x_write(is31, IS31FL319X_SHUTDOWN, 0x00);
> +	}
> +
> +	dev_dbg(&is31->client->dev, "work done\n");
> +
> +}
> +
> +/* NOTE: this may be called from within irq context, e.g. led_trigger_event */
> +
> +static int is31fl319x_brightness_get(struct led_classdev *led_cdev)
> +{
> +	struct is31fl319x_led *led = container_of(led_cdev,
> +						  struct is31fl319x_led,
> +						  led_cdev);
> +	struct is31fl319x_chip *is31 = led->chip;
> +
> +	/* read PWM register */
> +	return is31fl319x_read(is31, IS31FL319X_PWM1 + (led - is31->leds));
> +}
> +
> +static void is31fl319x_brightness_set(struct led_classdev *led_cdev,
> +				   enum led_brightness brightness)
> +{
> +	struct is31fl319x_led *led = container_of(led_cdev,
> +						  struct is31fl319x_led,
> +						  led_cdev);
> +	struct is31fl319x_chip *is31 = led->chip;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&is31->lock, flags);
> +
> +	if (brightness != is31fl319x_brightness_get(led_cdev)) {

Current brightness is cached in led_cdev->brightness.

> +		if (!is31->work_scheduled) {
> +			schedule_work(&is31->work);
> +			is31->work_scheduled = true;
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&is31->lock, flags);
> +}
> +
> +static int is31fl319x_blink_set(struct led_classdev *led_cdev,
> +			     unsigned long *delay_on,
> +			     unsigned long *delay_off)
> +{
> +	/* use software blink */
> +	return 1;
> +}

This function is useless, please remove it.

> +#ifdef CONFIG_OF

Please provide only version for CONFIG_OF defined case and just fail
probing if of_node is NULL.

> +static struct is31fl319x_platform_data *
> +is31fl319x_led_dt_init(struct i2c_client *client, int num_leds)

Please rename it to is31fl319x_parse_dt.

> +{
> +	struct device_node *np = client->dev.of_node, *child;
> +	struct is31fl319x_platform_data *pdata;
> +	struct led_info *is31_leds;
> +	int count;
> +
> +	count = of_get_child_count(np);
> +	dev_dbg(&client->dev, "child count %d\n", count);
> +	if (!count || count > NUM_LEDS)
> +		return ERR_PTR(-ENODEV);
> +
> +	is31_leds = devm_kzalloc(&client->dev,
> +			sizeof(struct led_info) * NUM_LEDS, GFP_KERNEL);
> +	if (!is31_leds)
> +		return ERR_PTR(-ENOMEM);
> +
> +	for_each_child_of_node(np, child) {
> +		struct led_info led;
> +		u32 reg;
> +		int ret;
> +
> +		led.name =
> +			of_get_property(child, "label", NULL) ? : child->name;
> +		led.default_trigger =
> +			of_get_property(child, "linux,default-trigger", NULL);
> +		led.flags = 0;
> +		ret = of_property_read_u32(child, "reg", &reg);
> +		dev_dbg(&client->dev, "name = %s reg = %d\n", led.name, reg);
> +		if (ret != 0 || reg < 0 || reg >= num_leds)
> +			continue;
> +
> +		if (is31_leds[reg].name)
> +			dev_err(&client->dev, "duplicate led line %d for %s -> %s\n",
> +				reg, is31_leds[reg].name, led.name);
> +		is31_leds[reg] = led;
> +	}
> +	pdata = devm_kzalloc(&client->dev,
> +			sizeof(struct is31fl319x_platform_data), GFP_KERNEL);
> +	if (!pdata)
> +		return ERR_PTR(-ENOMEM);
> +
> +	pdata->leds.leds = is31_leds;
> +	return pdata;
> +}
> +
> +static const struct of_device_id of_is31fl319x_leds_match[] = {
> +	{ .compatible = "issi,is31fl3196", (void *) 6 },
> +	{ .compatible = "issi,is31fl3199", (void *) 9 },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, of_is31fl319x_leds_match);
> +
> +#else
> +static struct is31fl319x_platform_data *
> +is31fl319x_led_dt_init(struct i2c_client *client)
> +{
> +	return ERR_PTR(-ENODEV);
> +}
> +
> +#endif
> +
> +static int is31fl319x_probe(struct i2c_client *client,
> +		const struct i2c_device_id *id)
> +{
> +	struct is31fl319x_chip *is31;
> +	struct i2c_adapter *adapter;
> +	struct is31fl319x_platform_data *pdata;
> +	int err;
> +	int i = 0;
> +
> +	adapter = to_i2c_adapter(client->dev.parent);
> +	pdata = dev_get_platdata(&client->dev);
> +
> +	dev_dbg(&client->dev, "probe\n");
> +
> +	dev_dbg(&client->dev, "NUM_LEDS = %d num_leds = %d\n",
> +		NUM_LEDS, (int) id->driver_data);

I believe this is stray debug logging.

> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
> +		return -EIO;
> +
> +	if (!pdata) {
> +		pdata = is31fl319x_led_dt_init(client, (int) id->driver_data);
> +		if (IS_ERR(pdata)) {
> +			dev_err(&client->dev, "DT led error %d\n",

s/DT led error/DT parsing error/

> +				(int) PTR_ERR(pdata));
> +			return PTR_ERR(pdata);
> +		}
> +	}
> +	is31 = devm_kzalloc(&client->dev, sizeof(*is31), GFP_KERNEL);
> +	if (!is31)
> +		return -ENOMEM;
> +
> +	is31->client = client;
> +	INIT_WORK(&is31->work, is31fl319x_work);
> +	spin_lock_init(&is31->lock);
> +	i2c_set_clientdata(client, is31);
> +
> +	/* check for reply from chip (we can't read any registers) */
> +	err = is31fl319x_write(is31, IS31FL319X_SHUTDOWN, 0x01);
> +	if (err < 0) {
> +		dev_err(&client->dev, "no response from chip write: err = %d\n",
> +			err);
> +		return -EPROBE_DEFER;	/* does not answer (yet) */

When can it happen? Does the chip have a long booting time or so?

> +	}
> +
> +	for (i = 0; i < NUM_LEDS; i++) {
> +		struct is31fl319x_led *l = is31->leds + i;
> +
> +		l->chip = is31;
> +		if (pdata->leds.leds[i].name && !pdata->leds.leds[i].flags) {
> +			l->led_cdev.name = pdata->leds.leds[i].name;
> +			l->led_cdev.default_trigger
> +				= pdata->leds.leds[i].default_trigger;
> +			l->led_cdev.brightness_set = is31fl319x_brightness_set;
> +			l->led_cdev.blink_set = is31fl319x_blink_set;
> +			err = led_classdev_register(&client->dev,
> +						    &l->led_cdev);
> +			if (err < 0)
> +				goto exit;
> +		}
> +	}
> +
> +	if (client->dev.of_node) {
> +		u32 val;
> +		u8 config2 = 0;
> +
> +		if (of_property_read_u32(client->dev.of_node, "max-current-ma",
> +					 &val)) {
> +			if (val > 40)
> +				val = 40;
> +			if (val < 5)
> +				val = 5;
> +			config2 |= (((64 - val) / 5) & 0x7) << 4; /* CS */
> +		}
> +		if (of_property_read_u32(client->dev.of_node, "audio-gain-db",
> +					 &val)) {
> +			if (val > 21)
> +				val = 21;
> +			config2 |= val / 3; /* AGS */
> +		}
> +		if (config2)
> +			is31fl319x_write(is31, IS31FL319X_CONFIG2, config2);
> +	}

Could you move the contents of this condition to is31fl319x_led_dt_init?

> +
> +	schedule_work(&is31->work);	/* first update */
> +
> +	dev_dbg(&client->dev, "probed\n");
> +	return 0;
> +exit:
> +	dev_err(&client->dev, "led error %d\n", err);
> +
> +	while (i--) {
> +		if (is31->leds[i].led_cdev.name)
> +			led_classdev_unregister(&is31->leds[i].led_cdev);
> +	}
> +	return err;
> +}
> +
> +static int is31fl319x_remove(struct i2c_client *client)
> +{
> +	int i;
> +	struct is31fl319x_chip *is31 = i2c_get_clientdata(client);
> +	struct is31fl319x_led *is31_leds = is31->leds;
> +
> +	for (i = 0; i < NUM_LEDS; i++) {
> +		if (is31_leds[i].led_cdev.name)
> +			led_classdev_unregister(&is31_leds[i].led_cdev);
> +	}
> +
> +	cancel_work_sync(&is31->work);
> +
> +	return 0;
> +}
> +
> +static struct i2c_driver is31fl319x_driver = {
> +	.driver   = {
> +		.name    = "leds-is31fl319x",
> +		.of_match_table = of_match_ptr(of_is31fl319x_leds_match),
> +	},
> +	.probe    = is31fl319x_probe,
> +	.remove   = is31fl319x_remove,
> +	.id_table = is31fl319x_id,
> +};
> +
> +module_i2c_driver(is31fl319x_driver);
> +
> +MODULE_AUTHOR("H. Nikolaus Schaller <hns at goldelico.com>");
> +MODULE_DESCRIPTION("IS31FL319X LED driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/leds-is31fl319x.h b/include/linux/leds-is31fl319x.h
> new file mode 100644
> index 0000000..5f55abf
> --- /dev/null
> +++ b/include/linux/leds-is31fl319x.h
> @@ -0,0 +1,24 @@
> +/*
> + * IS31FL3196 LED chip driver.
> + *
> + * Copyright (C) 2015 H. Nikolaus Schaller <hns at goldelico.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * General Public License for more details.
> + */
> +
> +#ifndef __LINUX_IS31FL319X_H
> +#define __LINUX_IS31FL319X_H
> +#include <linux/leds.h>
> +
> +struct is31fl319x_platform_data {
> +	struct led_platform_data leds;
> +};

We don't use led_platform_data for new drivers.
Device Tree has become a standard.
Effectively this header is not needed, please drop it.

> +#endif /* __LINUX_IS31FL319X_H */
>


-- 
Best regards,
Jacek Anaszewski


More information about the Letux-kernel mailing list