Message-id: <578DEA62.2010204@samsung.com>
Date:	Tue, 19 Jul 2016 10:52:50 +0200
From:	Jacek Anaszewski <j.anaszewski@...sung.com>
To:	"H. Nikolaus Schaller" <hns@...delico.com>
Cc:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Richard Purdie <rpurdie@...ys.net>, drivshin.allworx@...il.com,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-leds@...r.kernel.org, kernel@...a-handheld.com,
	marek@...delico.com, letux-kernel@...nphoenux.org,
	Andrey Utkin <andrey_utkin@...tmail.com>
Subject: Re: [PATCH v4 1/2] led: is31fl319x: 1/3/6/9-channel light effect led
 driver

Hi Nikolaus,

Thanks for the updated patch. I have one remark below.

On 07/19/2016 10:03 AM, 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@...delico.com>
> Signed-off-by: Andrey Utkin <andrey_utkin@...tmail.com>
> ---
>   drivers/leds/Kconfig           |  12 ++
>   drivers/leds/Makefile          |   1 +
>   drivers/leds/leds-is31fl319x.c | 442 +++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 455 insertions(+)
>   create mode 100644 drivers/leds/leds-is31fl319x.c
>
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 5ae2834..6439a7d 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -570,6 +570,18 @@ 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
> +	select REGMAP_I2C
> +	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.
> +
> +	  This driver can also be built as a module. If so the module will be
> +	  called leds-is31fl319x.
> +
>   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..268a23d
> --- /dev/null
> +++ b/drivers/leds/leds-is31fl319x.c
> @@ -0,0 +1,442 @@
> +/*
> + * Copyright 2015-16 Golden Delicious Computers
> + *
> + * Author: Nikolaus Schaller <hns@...delico.com>
> + *
> + * 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 IS31FL319{0,1,3,6,9} 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/of_device.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_PWM(channel) (0x07 + channel)
> +#define IS31FL319X_DATA_UPDATE  0x10
> +#define IS31FL319X_T0(channel)  (0x11 + channel)
> +#define IS31FL319X_T123_1       0x1a
> +#define IS31FL319X_T123_2       0x1b
> +#define IS31FL319X_T123_3       0x1c
> +#define IS31FL319X_T4(channel)  (0x1d + channel)
> +#define IS31FL319X_TIME_UPDATE  0x26
> +#define IS31FL319X_RESET        0xff
> +
> +#define IS31FL319X_REG_CNT      (IS31FL319X_RESET + 1)
> +
> +/* Shift of CS (Current Setting) in CONFIG2 register */
> +#define IS31FL319X_CONFIG2_CS_SHIFT 4
> +#define IS31FL319X_CONFIG2_CS_MASK  0x7
> +
> +#define IS31FL319X_MAX_LEDS 9
> +
> +#define IS31FL319X_CURRENT_MIN ((u32)5000)
> +#define IS31FL319X_CURRENT_MAX ((u32)40000)
> +#define IS31FL319X_CURRENT_STEP ((u32)5000)
> +#define IS31FL319X_CURRENT_DEFAULT ((u32)20000)
> +
> +#define IS31FL319X_AUDIO_GAIN_DB_MAX ((u32)21)
> +
> +/*
> + * regmap is used as a cache of chip's register space,
> + * to avoid reading back brightness values from chip,
> + * which is known to hang.
> + */
> +struct is31fl319x_chip {
> +	const struct is31fl319x_chipdef *cdef;
> +	struct i2c_client               *client;
> +	struct regmap                   *regmap;
> +	struct mutex                    lock;
> +	u32                             audio_gain_db;
> +
> +	struct is31fl319x_led {
> +		struct is31fl319x_chip  *chip;
> +		struct led_classdev     cdev;
> +		u32                     max_microamp;
> +		bool                    configured;
> +	} leds[IS31FL319X_MAX_LEDS];
> +};
> +
> +struct is31fl319x_chipdef {
> +	int num_leds;
> +};
> +
> +static const struct is31fl319x_chipdef is31fl3190_cdef = {
> +	.num_leds = 1,
> +};
> +
> +static const struct is31fl319x_chipdef is31fl3193_cdef = {
> +	.num_leds = 3,
> +};
> +
> +static const struct is31fl319x_chipdef is31fl3196_cdef = {
> +	.num_leds = 6,
> +};
> +
> +static const struct is31fl319x_chipdef is31fl3199_cdef = {
> +	.num_leds = 9,
> +};
> +
> +static const struct of_device_id of_is31fl319x_match[] = {
> +	{ .compatible = "issi,is31fl3190", .data = &is31fl3190_cdef, },
> +	{ .compatible = "issi,is31fl3191", .data = &is31fl3190_cdef, },
> +	{ .compatible = "issi,is31fl3193", .data = &is31fl3193_cdef, },
> +	{ .compatible = "issi,is31fl3196", .data = &is31fl3196_cdef, },
> +	{ .compatible = "issi,is31fl3199", .data = &is31fl3199_cdef, },
> +	{ .compatible = "si-en,sn3199",    .data = &is31fl3199_cdef, },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, of_is31fl319x_match);
> +
> +static int is31fl319x_brightness_set(struct led_classdev *cdev,
> +				     enum led_brightness brightness)
> +{
> +	struct is31fl319x_led *led = container_of(cdev, struct is31fl319x_led,
> +						  cdev);
> +	struct is31fl319x_chip *is31 = led->chip;
> +	int chan = led - is31->leds;
> +	int ret;
> +	int i;
> +	u8 ctrl1 = 0, ctrl2 = 0;
> +
> +	dev_dbg(&is31->client->dev, "%s %d: %d\n", __func__, chan, brightness);
> +
> +	mutex_lock(&is31->lock);
> +
> +	/* update PWM register */
> +	ret = regmap_write(is31->regmap, IS31FL319X_PWM(chan), brightness);
> +	if (ret < 0)
> +		goto out;
> +
> +	/* read current brightness of all PWM channels */
> +	for (i = 0; i < is31->cdef->num_leds; i++) {
> +		unsigned int pwm_value;
> +		bool on;
> +
> +		/*
> +		 * since neither cdev nor the chip can provide
> +		 * the current setting, we read from the regmap cache
> +		 */
> +
> +		ret = regmap_read(is31->regmap, IS31FL319X_PWM(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);
> +	}
> +
> +out:
> +	mutex_unlock(&is31->lock);
> +
> +	return ret;
> +}
> +
> +static int is31fl319x_parse_child_dt(const struct device *dev,
> +				     const struct device_node *child,
> +				     struct is31fl319x_led *led)
> +{
> +	struct led_classdev *cdev = &led->cdev;
> +	int ret;
> +
> +	if (of_property_read_string(child, "label", &cdev->name))
> +		cdev->name = child->name;
> +
> +	ret = of_property_read_string(child, "linux,default-trigger",
> +				      &cdev->default_trigger);
> +	if (ret < 0 && ret != -EINVAL) /* is optional */
> +		return ret;
> +
> +	led->max_microamp = IS31FL319X_CURRENT_DEFAULT;
> +	ret = of_property_read_u32(child, "led-max-microamp",
> +				   &led->max_microamp);
> +	if (!ret) {
> +		if (led->max_microamp < IS31FL319X_CURRENT_MIN)
> +			return -EINVAL;	/* not supported */
> +		led->max_microamp = min(led->max_microamp,
> +					  IS31FL319X_CURRENT_MAX);
> +	}
> +
> +	return 0;
> +}
> +
> +static int is31fl319x_parse_dt(struct device *dev,
> +			       struct is31fl319x_chip *is31)
> +{
> +	struct device_node *np = dev->of_node, *child;
> +	const struct of_device_id *of_dev_id;
> +	int count;
> +	int ret;
> +
> +	if (!np)
> +		return -ENODEV;
> +
> +	of_dev_id = of_match_device(of_is31fl319x_match, dev);
> +	if (!of_dev_id) {
> +		dev_err(dev, "Failed to match device with supported chips\n");
> +		return -EINVAL;
> +	}
> +
> +	is31->cdef = of_dev_id->data;
> +
> +	count = of_get_child_count(np);
> +
> +	dev_dbg(dev, "probe %s with %d leds defined in DT\n",
> +		of_dev_id->compatible, count);
> +
> +	if (!count || count > is31->cdef->num_leds) {
> +		dev_err(dev, "Number of leds defined must be between 1 and %u\n",
> +			is31->cdef->num_leds);
> +		return -ENODEV;
> +	}
> +
> +	for_each_child_of_node(np, child) {
> +		struct is31fl319x_led *led;
> +		u32 reg;
> +
> +		ret = of_property_read_u32(child, "reg", &reg);
> +		if (ret) {
> +			dev_err(dev, "Failed to read led 'reg' property\n");
> +			goto put_child_node;
> +		}
> +
> +		if (reg < 1 || reg > is31->cdef->num_leds) {
> +			dev_err(dev, "invalid led reg %u\n", reg);
> +			ret = -EINVAL;
> +			goto put_child_node;
> +		}
> +
> +		led = &is31->leds[reg - 1];
> +
> +		if (led->configured) {
> +			dev_err(dev, "led %u is already configured\n", reg);
> +			ret = -EINVAL;
> +			goto put_child_node;
> +		}
> +
> +		ret = is31fl319x_parse_child_dt(dev, child, led);
> +		if (ret) {
> +			dev_err(dev, "led %u DT parsing failed\n", reg);
> +			goto put_child_node;
> +		}
> +
> +		led->configured = true;
> +	}
> +
> +	is31->audio_gain_db = 0;
> +	ret = of_property_read_u32(np, "audio-gain-db", &is31->audio_gain_db);
> +	if (!ret) {
> +		is31->audio_gain_db = min(is31->audio_gain_db,
> +					  IS31FL319X_AUDIO_GAIN_DB_MAX);
> +		is31->audio_gain_db -= is31->audio_gain_db % 3;
> +	}
> +
> +	return 0;
> +
> +put_child_node:
> +	of_node_put(child);
> +	return ret;
> +}
> +
> +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;
> +	}
> +}
> +
> +static const struct reg_default is31fl319x_reg_defaults[] = {
> +	{ IS31FL319X_CONFIG1, 0x00},
> +	{ IS31FL319X_CONFIG2, 0x00},
> +	{ IS31FL319X_PWM(0), 0x00},
> +	{ IS31FL319X_PWM(1), 0x00},
> +	{ IS31FL319X_PWM(2), 0x00},
> +	{ IS31FL319X_PWM(3), 0x00},
> +	{ IS31FL319X_PWM(4), 0x00},
> +	{ IS31FL319X_PWM(5), 0x00},
> +	{ IS31FL319X_PWM(6), 0x00},
> +	{ IS31FL319X_PWM(7), 0x00},
> +	{ IS31FL319X_PWM(8), 0x00},
> +};
> +
> +static 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,
> +	.reg_defaults = is31fl319x_reg_defaults,
> +	.num_reg_defaults = ARRAY_SIZE(is31fl319x_reg_defaults),
> +};
> +
> +static int is31fl319x_microamp_to_cs(struct device *dev, u32 microamp)
> +{ /* round down to nearest supported value (range check done by caller) */
> +	u32 step = microamp / IS31FL319X_CURRENT_STEP;
> +
> +	return (12 - step) & IS31FL319X_CONFIG2_CS_MASK; /* CS encoding */
> +}
> +
> +static int is31fl319x_probe(struct i2c_client *client,
> +			    const struct i2c_device_id *id)
> +{
> +	struct is31fl319x_chip *is31;
> +	struct device *dev = &client->dev;
> +	struct i2c_adapter *adapter = to_i2c_adapter(dev->parent);
> +	int err;
> +	int i = 0;
> +	u32 aggregated_led_microamp = IS31FL319X_CURRENT_MAX;
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
> +		return -EIO;
> +
> +	is31 = devm_kzalloc(&client->dev, sizeof(*is31), GFP_KERNEL);
> +	if (!is31)
> +		return -ENOMEM;
> +
> +	mutex_init(&is31->lock);
> +
> +	err = is31fl319x_parse_dt(&client->dev, is31);
> +	if (err)
> +		goto free_mutex;
> +
> +	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");
> +		err = PTR_ERR(is31->regmap);
> +		goto free_mutex;
> +	}
> +
> +	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);
> +	if (err < 0) {
> +		dev_err(&client->dev, "no response from chip write: err = %d\n",
> +			err);
> +		err = -EIO; /* does not answer */
> +		goto free_mutex;
> +	}
> +
> +	/*
> +	 * Kernel conventions require per-LED led-max-microamp property.
> +	 * But the chip does not allow to limit individual LEDs.
> +	 * So we take minimum from all subnodes for safety of hardware.
> +	 */
> +	for (i = 0; i < is31->cdef->num_leds; i++)
> +		if (is31->leds[i].configured &&
> +		    is31->leds[i].max_microamp < aggregated_led_microamp)
> +			aggregated_led_microamp = is31->leds[i].max_microamp;
> +
> +	regmap_write(is31->regmap, IS31FL319X_CONFIG2,
> +		     is31fl319x_microamp_to_cs(dev, aggregated_led_microamp) <<
> +		     IS31FL319X_CONFIG2_CS_SHIFT | is31->audio_gain_db / 3);

The third argument looks to complex. Please add a macro for
calculating CONFIG2 register value basing on the aggregated_led_microamp
value.

I'd also add brackets to improve readability.

> +
> +	for (i = 0; i < is31->cdef->num_leds; i++) {
> +		struct is31fl319x_led *led = &is31->leds[i];
> +
> +		if (!led->configured)
> +			continue;
> +
> +		led->chip = is31;
> +		led->cdev.brightness_set_blocking = is31fl319x_brightness_set;
> +
> +		err = devm_led_classdev_register(&client->dev, &led->cdev);
> +		if (err < 0)
> +			goto free_mutex;
> +	}
> +
> +	return 0;
> +
> +free_mutex:
> +	mutex_destroy(&is31->lock);
> +	return err;
> +}
> +
> +static int is31fl319x_remove(struct i2c_client *client)
> +{
> +	struct is31fl319x_chip *is31 = i2c_get_clientdata(client);
> +
> +	mutex_destroy(&is31->lock);
> +	return 0;
> +}
> +
> +/*
> + * i2c-core (and modalias) requires that id_table be properly filled,
> + * even though it is not used for DeviceTree based instantiation.
> + */
> +static const struct i2c_device_id is31fl319x_id[] = {
> +	{ "is31fl3190" },
> +	{ "is31fl3191" },
> +	{ "is31fl3193" },
> +	{ "is31fl3196" },
> +	{ "is31fl3199" },
> +	{ "sn3199" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(i2c, is31fl319x_id);
> +
> +static struct i2c_driver is31fl319x_driver = {
> +	.driver   = {
> +		.name           = "leds-is31fl319x",
> +		.of_match_table = of_match_ptr(of_is31fl319x_match),
> +	},
> +	.probe    = is31fl319x_probe,
> +	.remove   = is31fl319x_remove,
> +	.id_table = is31fl319x_id,
> +};
> +
> +module_i2c_driver(is31fl319x_driver);
> +
> +MODULE_AUTHOR("H. Nikolaus Schaller <hns@...delico.com>");
> +MODULE_AUTHOR("Andrey Utkin <andrey_utkin@...tmail.com>");
> +MODULE_DESCRIPTION("IS31FL319X LED driver");
> +MODULE_LICENSE("GPL v2");
>


-- 
Best regards,
Jacek Anaszewski

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