[Letux-kernel] [PATCH v2 1/2] drivers: led: is31fl319x: 1/3/6/9-channel light effect led driver

Jacek Anaszewski j.anaszewski at samsung.com
Thu Jul 7 10:47:07 CEST 2016


Hi Nikolaus,

Thanks for the updated version. Some comments below.

On 07/06/2016 12:02 PM, H. Nikolaus Schaller wrote:
> This is a driver for the Integrated Silicon Solution Inc. LED driver
> chips series IS31FL319x. They can drive 1, 3, 6  or up to 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
> in the range 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 fully
> supported by this driver.
>
> Tested-on: OMAP5 based Pyra handheld prototype.
> Signed-off-by: H. Nikolaus Schaller <hns at goldelico.com>
> ---
>   drivers/leds/Kconfig           |   8 +
>   drivers/leds/Makefile          |   1 +
>   drivers/leds/leds-is31fl319x.c | 354 +++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 363 insertions(+)
>   create mode 100644 drivers/leds/leds-is31fl319x.c
>
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 5ae2834..65b1045 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -570,6 +570,14 @@ config LEDS_SEAD3
>   	  This driver can also be built as a module. If so the module
>   	  will be called leds-sead3.
>
> +config LEDS_IS31FL319X
> +	tristate "LED Support for ISSI IS31FL319x I2C LED controller family"
> +	depends on LEDS_CLASS && I2C && OF
> +	help
> +	  This option enables support for LEDs connected to ISSI IS31FL319x
> +	  fancy LED driver chips accessed via the I2C bus.
> +	  Driver supports individual PWM brightness control for each channel.
> +
>   config LEDS_IS31FL32XX
>   	tristate "LED support for ISSI IS31FL32XX I2C LED controller family"
>   	depends on LEDS_CLASS && I2C && OF
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index cb2013d..b6ce9f9 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -66,6 +66,7 @@ obj-$(CONFIG_LEDS_MENF21BMC)		+= leds-menf21bmc.o
>   obj-$(CONFIG_LEDS_KTD2692)		+= leds-ktd2692.o
>   obj-$(CONFIG_LEDS_POWERNV)		+= leds-powernv.o
>   obj-$(CONFIG_LEDS_SEAD3)		+= leds-sead3.o
> +obj-$(CONFIG_LEDS_IS31FL319X)		+= leds-is31fl319x.o
>   obj-$(CONFIG_LEDS_IS31FL32XX)		+= leds-is31fl32xx.o
>
>   # LED SPI Drivers
> diff --git a/drivers/leds/leds-is31fl319x.c b/drivers/leds/leds-is31fl319x.c
> new file mode 100644
> index 0000000..bbf8850
> --- /dev/null
> +++ b/drivers/leds/leds-is31fl319x.c
> @@ -0,0 +1,354 @@
> +/*
> + * Copyright 2015-16 Golden Delicious 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 IS31FL3191/3/6/99 to drive 1, 3, 6 or 9 light
> + * effect LEDs.
> + *
> + */
> +
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +
> +/* 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_RESET	0xff
> +
> +#define IS31FL319X_REG_CNT	(IS31FL319X_RESET + 1)
> +
> +#define NUM_LEDS 9	/* max for 3199 chip */
> +
> +struct is31fl319x_chip {
> +	struct i2c_client	*client;
> +	struct regmap		*regmap;
> +
> +	struct is31fl319x_led {
> +		struct is31fl319x_chip	*chip;
> +		struct led_classdev	led_cdev;
> +	} leds[NUM_LEDS];
> +};
> +
> +static const struct i2c_device_id is31fl319x_id[] = {
> +	{ "is31fl3190", 1 },
> +	{ "is31fl3191", 1 },
> +	{ "is31fl3193", 3 },
> +	{ "is31fl3196", 6 },
> +	{ "is31fl3199", 9 },
> +	{ "sn3199", 9 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, is31fl319x_id);
> +
> +static int 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;
> +	int ret;
> +
> +	int i;
> +	u8 ctrl1, ctrl2;

You can initialize these variables here.

> +
> +	dev_dbg(&is31->client->dev, "%s %d: %d\n", __func__, (led - is31->leds),
> +		brightness);
> +
> +	/* update PWM register */
> +	ret = regmap_write(is31->regmap, IS31FL319X_PWM1 + (led - is31->leds),
> +			   brightness);
> +	if (ret < 0)
> +		return ret;
> +
> +	ctrl1 = 0;
> +	ctrl2 = 0;

And remove above two lines.

> +
> +	/* read current brightness of all PWM channels */
> +	for (i = 0; i < NUM_LEDS; i++) {
> +		unsigned int pwm_value;
> +		bool on;
> +
> +		/*
> +		 * since neither led_cdev nor the chip can provide
> +		 * the current setting, we read from the regmap cache
> +		 */
> +
> +		ret = regmap_read(is31->regmap, IS31FL319X_PWM1 + i,
> +				  &pwm_value);
 > +
> +		dev_dbg(&is31->client->dev, "%s read %d: ret=%d: %d\n",
> +			__func__, i, ret, pwm_value);
> +		on = ret >= 0 && pwm_value > LED_OFF;
> +
> +		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 */
> +	}
 > +
> +
> +	if (ctrl1 > 0 || ctrl2 > 0) {
> +		dev_dbg(&is31->client->dev, "power up %02x %02x\n",
> +			ctrl1, ctrl2);
> +		regmap_write(is31->regmap, IS31FL319X_CTRL1, ctrl1);
> +		regmap_write(is31->regmap, IS31FL319X_CTRL2, ctrl2);
> +		/* update PWMs */
> +		regmap_write(is31->regmap, IS31FL319X_DATA_UPDATE, 0x00);
> +		/* enable chip from shut down */
> +		ret = regmap_write(is31->regmap, IS31FL319X_SHUTDOWN, 0x01);
> +	} else {
> +		dev_dbg(&is31->client->dev, "power down\n");
> +		/* shut down (no need to clear CTRL1/2) */
> +		ret = regmap_write(is31->regmap, IS31FL319X_SHUTDOWN, 0x00);
> +	}

You need a mutex protection in this function, so as to prevent other
processes from jumping in in the middle of setting up a brightness,
which requires writing several registers.

> +	return ret;
> +}
> +
> +static struct led_info *
> +is31fl319x_parse_dt(struct i2c_client *client, int num_leds)
> +{
> +	struct device_node *np = client->dev.of_node, *child;
> +	struct led_info *is31_leds;
> +	int count;
> +
> +	if (!np)
> +		return ERR_PTR(-ENODEV);
> +
> +	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;

Using this local variable adds too much noise here.
I suggest avoiding the use of struct led_info. It is semantically
inconsistent in the context of DT parsing, since you don't have
any flags to parse.

> +		u32 reg;
> +		int ret;
> +
> +		led.name = NULL;
> +		ret = of_property_read_string(child, "label", &led.name);
> +		if (ret < 0 && ret != -EINVAL)	/* is optional */
> +			return ERR_PTR(ret);

You could assign the name directly to related struct led_classdev
property. Moreover, if label is not present the child node name
should be used for LED class device name. Please refer to the other
drivers and common LED bindings.

> +		led.default_trigger = NULL;
> +		ret = of_property_read_string(child, "linux,default-trigger",
> +			&led.default_trigger);

Here also please assign the trigger directly to struct led_classdev.

> +		if (ret < 0 && ret != -EINVAL)	/* is optional */
> +			return ERR_PTR(ret);
> +		led.flags = 0;
> +		ret = of_property_read_u32(child, "reg", &reg);
> +		dev_dbg(&client->dev, "name = %s reg = %d\n", led.name, reg);
> +		reg -= 1;	/* index 0 is at reg = 1 */
> +		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;
> +	}
> +
> +	return is31_leds;
> +}
> +
> +static const struct of_device_id of_is31fl319x_leds_match[] = {
> +	{ .compatible = "issi,is31fl3190", (void *) 1 },
> +	{ .compatible = "issi,is31fl3191", (void *) 1 },
> +	{ .compatible = "issi,is31fl3193", (void *) 3 },
> +	{ .compatible = "issi,is31fl3196", (void *) 6 },
> +	{ .compatible = "issi,is31fl3199", (void *) 9 },
> +	{ .compatible = "si-en,sn3199", (void *) 9 },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, of_is31fl319x_leds_match);
> +
> +static bool is31fl319x_readable_reg(struct device *dev, unsigned int reg)
> +{ /* we have no readable registers */
> +	return false;
> +}
> +
> +static bool is31fl319x_volatile_reg(struct device *dev, unsigned int reg)
> +{ /* volatile registers are not cached */
> +	switch (reg) {
> +	case IS31FL319X_DATA_UPDATE:
> +	case IS31FL319X_TIME_UPDATE:
> +	case IS31FL319X_RESET:
> +		return true;	/* always write-through */
> +	default:
> +		return false;
> +	}
> +}
> +
> +struct regmap_config regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = IS31FL319X_REG_CNT,
> +	.cache_type = REGCACHE_FLAT,
> +	.readable_reg = is31fl319x_readable_reg,
> +	.volatile_reg = is31fl319x_volatile_reg,
> +};
> +
> +static int is31fl319x_probe(struct i2c_client *client,
> +		const struct i2c_device_id *id)
> +{
> +	struct is31fl319x_chip *is31;
> +	struct i2c_adapter *adapter;
> +	struct led_info *leds;
> +	int err;
> +	int i = 0;
> +
> +	adapter = to_i2c_adapter(client->dev.parent);
> +
> +	dev_dbg(&client->dev, "probe IS31FL319x for num_leds = %d\n",
> +		(int) id->driver_data);
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
> +		return -EIO;
> +
> +	leds = is31fl319x_parse_dt(client, (int) id->driver_data);
> +	if (IS_ERR(leds)) {
> +		dev_err(&client->dev, "DT parsing error %d\n",
> +			(int) PTR_ERR(leds));
> +		return PTR_ERR(leds);
> +	}
> +
> +	is31 = devm_kzalloc(&client->dev, sizeof(*is31), GFP_KERNEL);
> +	if (!is31)
> +		return -ENOMEM;
> +
> +	is31->client = client;
> +	is31->regmap = devm_regmap_init_i2c(client, &regmap_config);
> +	if (IS_ERR(is31->regmap)) {
> +		dev_err(&client->dev, "failed to allocate register map\n");
> +		return PTR_ERR(is31->regmap);
> +	}
> +
> +	i2c_set_clientdata(client, is31);
> +
> +	/* check for write-reply from chip (we can't read any registers) */
> +	err = regmap_write(is31->regmap, IS31FL319X_RESET, 0x00);

Doesn't powering the device up result in loading registers with default
values?

> +	if (err < 0) {
> +		dev_err(&client->dev, "no response from chip write: err = %d\n",
> +			err);
> +		return -EIO;	/* does not answer */
> +	}
> +
> +	/* initialize chip and regmap so that we never try to read from i2c */

You can initialize default register values without writing them,
by using regmap's reg_defaults property.

> +	regmap_write(is31->regmap, IS31FL319X_CTRL1, 0x00);
> +	regmap_write(is31->regmap, IS31FL319X_CTRL2, 0x00);
> +	for (i = 0; i < NUM_LEDS; i++)
> +		regmap_write(is31->regmap, IS31FL319X_PWM1 + i, 0x00);
> +
> +	if (client->dev.of_node) {
> +		u32 val;
> +		u8 config2 = 0;
> +
> +		if (of_property_read_u32(client->dev.of_node,
> +					 "led-max-microamp", &val)) {

of_property_read_u32 returns 0 on success.

led-max-microamp needs to be defined per each sub-LED (child node).
The greatest value should be used for setting CS bit field of CTRL2
register, and max_brightness values of the LEDs with lower max microamp
value should be limited accordingly.

Moreover, this is still DT parsing and should find its place in
is31fl319x_parse_dt().

> +			if (val > 40000)
> +				val = 40000;
> +			if (val < 5000)
> +				val = 5000;
> +			config2 |= (((64000 - val) / 5000) & 0x7) << 4; /* CS */
> +		}
> +		if (of_property_read_u32(client->dev.of_node, "audio-gain-db",
> +					 &val)) {

Please move this to is31fl319x_parse_dt().

> +			if (val > 21)
> +				val = 21;
> +			config2 |= val / 3; /* AGS */
> +		}
> +		regmap_write(is31->regmap, IS31FL319X_CONFIG2, config2);
> +	}
> +
> +	for (i = 0; i < NUM_LEDS; i++) {
> +		struct is31fl319x_led *l = is31->leds + i;
> +
> +		l->chip = is31;
> +		if (leds[i].name && !leds[i].flags) {
> +			l->led_cdev.name = leds[i].name;
> +			l->led_cdev.default_trigger
> +				= leds[i].default_trigger;
> +			l->led_cdev.brightness_set_blocking
> +				= is31fl319x_brightness_set;
> +			/* NOTE: is31fl319x_brightness_set will be called
> +			 * immediately after register() before we return
> +			 */

Who will call it? I believe that this is true only if default-on
trigger is registered.

> +			err = devm_led_classdev_register(&client->dev,
> +						    &l->led_cdev);
> +			if (err < 0)
> +				return err;
> +		}
> +	}
> +
> +	dev_dbg(&client->dev, "probed\n");

Please remove this debug log. You can verify it by checking presence of
the device in the sysfs.

> +	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,
> +	.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");
>


-- 
Best regards,
Jacek Anaszewski


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