diff mbox series

[v3,2/2] backlight: mp3309c: Add support for MPS MP3309C

Message ID 20230925122609.78849-2-f.suligoi@asem.it
State New
Headers show
Series None | expand

Commit Message

Flavio Suligoi Sept. 25, 2023, 12:26 p.m. UTC
The Monolithic Power (MPS) MP3309C is a WLED step-up converter, featuring a
programmable switching frequency to optimize efficiency.
The brightness can be controlled either by I2C commands (called "analog"
mode) or by a PWM input signal (PWM mode).
This driver supports both modes.

For DT configuration details, please refer to:
- Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml

The datasheet is available at:
- https://www.monolithicpower.com/en/mp3309c.html

Signed-off-by: Flavio Suligoi <f.suligoi@asem.it>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
---

v3:
 - fix SPDX obsolete spelling
 - in mp3309c_bl_update_status, change from msleep_interruptible() to msleep()
   and improve the related comment
v2:
 - fix dependecies in Kconfig
 - fix Kconfig MP3309C entry order
 - remove switch-on-delay-ms property
 - remove optional gpio property to reset external devices
 - remove dimming-mode property (the analog-i2c dimming mode is the default; the
   presence of the pwms property, in DT, selects automatically the pwm dimming
   mode)
 - substitute three boolean properties, used for the overvoltage-protection
   values, with a single enum property
 - drop simple tracing messages
 - use dev_err_probe() in probe function
 - change device name from mp3309c_bl to the simple mp3309c
 - remove shutdown function
v1:
 - first version

 MAINTAINERS                       |   6 +
 drivers/video/backlight/Kconfig   |  11 +
 drivers/video/backlight/Makefile  |   1 +
 drivers/video/backlight/mp3309c.c | 398 ++++++++++++++++++++++++++++++
 4 files changed, 416 insertions(+)
 create mode 100644 drivers/video/backlight/mp3309c.c

Comments

Daniel Thompson Sept. 26, 2023, 1:10 p.m. UTC | #1
On Mon, Sep 25, 2023 at 02:26:09PM +0200, Flavio Suligoi wrote:
> diff --git a/drivers/video/backlight/mp3309c.c b/drivers/video/backlight/mp3309c.c
> new file mode 100644
> index 000000000000..923ac7f7b291
> --- /dev/null
> +++ b/drivers/video/backlight/mp3309c.c
> @@ -0,0 +1,398 @@
> ...
> +static int mp3309c_bl_update_status(struct backlight_device *bl)
> +{
> +	struct mp3309c_chip *chip = bl_get_data(bl);
> +	int brightness = backlight_get_brightness(bl);
> +	struct pwm_state pwmstate;
> +	unsigned int analog_val, bits_val;
> +	int i, ret;
> +
> +	if (chip->pdata->dimming_mode == DIMMING_PWM) {
> +		/*
> +		 * PWM dimming mode
> +		 */
> +		pwm_get_state(chip->pwmd, &pwmstate);
> +		pwm_set_relative_duty_cycle(&pwmstate, brightness,
> +					    chip->pdata->max_brightness);
> +		pwmstate.enabled = true;
> +		ret = pwm_apply_state(chip->pwmd, &pwmstate);
> +		if (ret)
> +			return ret;
> +
> +		switch (chip->pdata->status) {
> +		case FIRST_POWER_ON:
> +		case BACKLIGHT_OFF:
> +			/*
> +			 * After 20ms of low pwm signal level, the chip turns
> +			   off automatically. In this case, before enabling the
> +			   chip again, we must wait about 10ms for pwm signal to
> +			   stabilize.
> +			 */
> +			if (brightness > 0) {
> +				msleep(10);
> +				mp3309c_enable_device(chip);
> +				chip->pdata->status = BACKLIGHT_ON;
> +			} else {
> +				chip->pdata->status = BACKLIGHT_OFF;
> +			}
> +			break;
> +		case BACKLIGHT_ON:
> +			if (brightness == 0)
> +				chip->pdata->status = BACKLIGHT_OFF;
> +			break;
> +		}
> +	} else {
> +		/*
> +		 * Analog dimming (by I2C command) dimming mode
> +		 *
> +		 * The first time, before setting brightness, we must enable the
> +		 * device
> +		 */
> +		if (chip->pdata->status == FIRST_POWER_ON)
> +			mp3309c_enable_device(chip);
> +
> +		/*
> +		 * Dimming mode I2C command
> +		 *
> +		 * The 5 bits of the dimming analog value D4..D0 is allocated
> +		 * in the I2C register #0, in the following way:
> +		 *
> +		 *     +--+--+--+--+--+--+--+--+
> +		 *     |EN|D0|D1|D2|D3|D4|XX|XX|
> +		 *     +--+--+--+--+--+--+--+--+
> +		 */
> +		analog_val = DIV_ROUND_UP(ANALOG_MAX_VAL * brightness,
> +					  chip->pdata->max_brightness);

Sorry to only notice after sharing a Reviewed-by:[1] but...

Scaling brightness here isn't right. When running in I2C dimming mode then
max_brightness *must* be 31 or lower, meaning the value in brightness can
be applied directly to the hardware without scaling.

Quoting the DT binding docs about how max-brightness should be
interpretted:

  Normally the maximum brightness is determined by the hardware and this
  property is not required. This property is used to put a software
  limit on the brightness apart from what the driver says, as it could
  happen that a LED can be made so bright that it gets damaged or causes
  damage due to restrictions in a specific system, such as mounting
  conditions.


Daniel.


[1] I remember checking if this code could overflow the field but I was
    so distracted by that I ended up missing the obvious!
Flavio Suligoi Oct. 3, 2023, 9:45 a.m. UTC | #2
Hi Daniel,

...

> > +static int mp3309c_bl_update_status(struct backlight_device *bl) {
> > +	struct mp3309c_chip *chip = bl_get_data(bl);
> > +	int brightness = backlight_get_brightness(bl);
> > +	struct pwm_state pwmstate;
> > +	unsigned int analog_val, bits_val;
> > +	int i, ret;
> > +
> > +	if (chip->pdata->dimming_mode == DIMMING_PWM) {
> > +		/*
> > +		 * PWM dimming mode
> > +		 */
> > +		pwm_get_state(chip->pwmd, &pwmstate);
> > +		pwm_set_relative_duty_cycle(&pwmstate, brightness,
> > +					    chip->pdata->max_brightness);
> > +		pwmstate.enabled = true;
> > +		ret = pwm_apply_state(chip->pwmd, &pwmstate);
> > +		if (ret)
> > +			return ret;
> > +
> > +		switch (chip->pdata->status) {
> > +		case FIRST_POWER_ON:
> > +		case BACKLIGHT_OFF:
> > +			/*
> > +			 * After 20ms of low pwm signal level, the chip turns
> > +			   off automatically. In this case, before enabling the
> > +			   chip again, we must wait about 10ms for pwm signal
> to
> > +			   stabilize.
> > +			 */
> > +			if (brightness > 0) {
> > +				msleep(10);
> > +				mp3309c_enable_device(chip);
> > +				chip->pdata->status = BACKLIGHT_ON;
> > +			} else {
> > +				chip->pdata->status = BACKLIGHT_OFF;
> > +			}
> > +			break;
> > +		case BACKLIGHT_ON:
> > +			if (brightness == 0)
> > +				chip->pdata->status = BACKLIGHT_OFF;
> > +			break;
> > +		}
> > +	} else {
> > +		/*
> > +		 * Analog dimming (by I2C command) dimming mode
> > +		 *
> > +		 * The first time, before setting brightness, we must enable the
> > +		 * device
> > +		 */
> > +		if (chip->pdata->status == FIRST_POWER_ON)
> > +			mp3309c_enable_device(chip);
> > +
> > +		/*
> > +		 * Dimming mode I2C command
> > +		 *
> > +		 * The 5 bits of the dimming analog value D4..D0 is allocated
> > +		 * in the I2C register #0, in the following way:
> > +		 *
> > +		 *     +--+--+--+--+--+--+--+--+
> > +		 *     |EN|D0|D1|D2|D3|D4|XX|XX|
> > +		 *     +--+--+--+--+--+--+--+--+
> > +		 */
> > +		analog_val = DIV_ROUND_UP(ANALOG_MAX_VAL *
> brightness,
> > +					  chip->pdata->max_brightness);
> 
> Sorry to only notice after sharing a Reviewed-by:[1] but...
> 
> Scaling brightness here isn't right. When running in I2C dimming mode then
> max_brightness *must* be 31 or lower, meaning the value in brightness can
> be applied directly to the hardware without scaling.

ok, right; max brightness is 31, fixed

> 
> Quoting the DT binding docs about how max-brightness should be
> interpretted:
> 
>   Normally the maximum brightness is determined by the hardware and this
>   property is not required. This property is used to put a software
>   limit on the brightness apart from what the driver says, as it could
>   happen that a LED can be made so bright that it gets damaged or causes
>   damage due to restrictions in a specific system, such as mounting
>   conditions.
> 

ok

> 
> Daniel.
> 
> 
> [1] I remember checking if this code could overflow the field but I was
>     so distracted by that I ended up missing the obvious!

Thanks and best regards,
Flavio
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 3be1bdfe8ecc..f779df433af1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14333,6 +14333,12 @@  S:	Maintained
 F:	Documentation/driver-api/tty/moxa-smartio.rst
 F:	drivers/tty/mxser.*
 
+MP3309C BACKLIGHT DRIVER
+M:	Flavio Suligoi <f.suligoi@asem.it>
+S:	Maintained
+F:	Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
+F:	drivers/video/backlight/mp3309c.c
+
 MR800 AVERMEDIA USB FM RADIO DRIVER
 M:	Alexey Klimov <klimov.linux@gmail.com>
 L:	linux-media@vger.kernel.org
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 51387b1ef012..1144a54a35c0 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -402,6 +402,17 @@  config BACKLIGHT_LP8788
 	help
 	  This supports TI LP8788 backlight driver.
 
+config BACKLIGHT_MP3309C
+	tristate "Backlight Driver for MPS MP3309C"
+	depends on I2C && PWM
+	select REGMAP_I2C
+	help
+	  This supports MPS MP3309C backlight WLED driver in both PWM and
+	  analog/I2C dimming modes.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called mp3309c.
+
 config BACKLIGHT_PANDORA
 	tristate "Backlight driver for Pandora console"
 	depends on TWL4030_CORE
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index f72e1c3c59e9..1af583de665b 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -44,6 +44,7 @@  obj-$(CONFIG_BACKLIGHT_LP855X)		+= lp855x_bl.o
 obj-$(CONFIG_BACKLIGHT_LP8788)		+= lp8788_bl.o
 obj-$(CONFIG_BACKLIGHT_LV5207LP)	+= lv5207lp.o
 obj-$(CONFIG_BACKLIGHT_MAX8925)		+= max8925_bl.o
+obj-$(CONFIG_BACKLIGHT_MP3309C)		+= mp3309c.o
 obj-$(CONFIG_BACKLIGHT_MT6370)		+= mt6370-backlight.o
 obj-$(CONFIG_BACKLIGHT_OMAP1)		+= omap1_bl.o
 obj-$(CONFIG_BACKLIGHT_PANDORA)		+= pandora_bl.o
diff --git a/drivers/video/backlight/mp3309c.c b/drivers/video/backlight/mp3309c.c
new file mode 100644
index 000000000000..923ac7f7b291
--- /dev/null
+++ b/drivers/video/backlight/mp3309c.c
@@ -0,0 +1,398 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for MPS MP3309C White LED driver with I2C interface
+ *
+ * Copyright (C) 2023 ASEM Srl
+ * Author: Flavio Suligoi <f.suligoi@asem.it>
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+
+#define REG_I2C_0	0x00
+#define REG_I2C_1	0x01
+
+#define REG_I2C_0_EN	0x80
+#define REG_I2C_0_D0	0x40
+#define REG_I2C_0_D1	0x20
+#define REG_I2C_0_D2	0x10
+#define REG_I2C_0_D3	0x08
+#define REG_I2C_0_D4	0x04
+#define REG_I2C_0_RSRV1	0x02
+#define REG_I2C_0_RSRV2	0x01
+
+#define REG_I2C_1_RSRV1	0x80
+#define REG_I2C_1_DIMS	0x40
+#define REG_I2C_1_SYNC	0x20
+#define REG_I2C_1_OVP0	0x10
+#define REG_I2C_1_OVP1	0x08
+#define REG_I2C_1_VOS	0x04
+#define REG_I2C_1_LEDO	0x02
+#define REG_I2C_1_OTP	0x01
+
+#define ANALOG_MAX_VAL	31
+#define ANALOG_REG_MASK 0x7c
+
+enum mp3309c_status_value {
+	FIRST_POWER_ON,
+	BACKLIGHT_OFF,
+	BACKLIGHT_ON,
+};
+
+enum mp3309c_dimming_mode_value {
+	DIMMING_PWM,
+	DIMMING_ANALOG_I2C,
+};
+
+struct mp3309c_platform_data {
+	u32 max_brightness;
+	u32 default_brightness;
+	u8  dimming_mode;
+	u8  over_voltage_protection;
+	bool sync_mode;
+	u8 status;
+};
+
+struct mp3309c_chip {
+	struct device *dev;
+	struct mp3309c_platform_data *pdata;
+	struct backlight_device *bl;
+	struct gpio_desc *enable_gpio;
+	struct regmap *regmap;
+	struct pwm_device *pwmd;
+	int irq;
+	struct gpio_desc *reset_gpio;
+};
+
+static const struct regmap_config mp3309c_regmap = {
+	.name = "mp3309c_regmap",
+	.reg_bits = 8,
+	.reg_stride = 1,
+	.val_bits = 8,
+	.max_register = REG_I2C_1,
+};
+
+static int mp3309c_enable_device(struct mp3309c_chip *chip)
+{
+	u8 reg_val;
+	int ret;
+
+	/* I2C register #0 - Device enable */
+	ret = regmap_update_bits(chip->regmap, REG_I2C_0, REG_I2C_0_EN,
+				 REG_I2C_0_EN);
+	if (ret)
+		return ret;
+
+	/*
+	 * I2C register #1 - Set working mode:
+	 *  - set one of the two dimming mode:
+	 *    - PWM dimming using an external PWM dimming signal
+	 *    - analog dimming using I2C commands
+	 *  - enable/disable synchronous mode
+	 *  - set overvoltage protection (OVP)
+	 */
+	reg_val = 0x00;
+	if (chip->pdata->dimming_mode == DIMMING_PWM)
+		reg_val |= REG_I2C_1_DIMS;
+	if (chip->pdata->sync_mode)
+		reg_val |= REG_I2C_1_SYNC;
+	reg_val |= chip->pdata->over_voltage_protection;
+	ret = regmap_write(chip->regmap, REG_I2C_1, reg_val);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int mp3309c_bl_update_status(struct backlight_device *bl)
+{
+	struct mp3309c_chip *chip = bl_get_data(bl);
+	int brightness = backlight_get_brightness(bl);
+	struct pwm_state pwmstate;
+	unsigned int analog_val, bits_val;
+	int i, ret;
+
+	if (chip->pdata->dimming_mode == DIMMING_PWM) {
+		/*
+		 * PWM dimming mode
+		 */
+		pwm_get_state(chip->pwmd, &pwmstate);
+		pwm_set_relative_duty_cycle(&pwmstate, brightness,
+					    chip->pdata->max_brightness);
+		pwmstate.enabled = true;
+		ret = pwm_apply_state(chip->pwmd, &pwmstate);
+		if (ret)
+			return ret;
+
+		switch (chip->pdata->status) {
+		case FIRST_POWER_ON:
+		case BACKLIGHT_OFF:
+			/*
+			 * After 20ms of low pwm signal level, the chip turns
+			   off automatically. In this case, before enabling the
+			   chip again, we must wait about 10ms for pwm signal to
+			   stabilize.
+			 */
+			if (brightness > 0) {
+				msleep(10);
+				mp3309c_enable_device(chip);
+				chip->pdata->status = BACKLIGHT_ON;
+			} else {
+				chip->pdata->status = BACKLIGHT_OFF;
+			}
+			break;
+		case BACKLIGHT_ON:
+			if (brightness == 0)
+				chip->pdata->status = BACKLIGHT_OFF;
+			break;
+		}
+	} else {
+		/*
+		 * Analog dimming (by I2C command) dimming mode
+		 *
+		 * The first time, before setting brightness, we must enable the
+		 * device
+		 */
+		if (chip->pdata->status == FIRST_POWER_ON)
+			mp3309c_enable_device(chip);
+
+		/*
+		 * Dimming mode I2C command
+		 *
+		 * The 5 bits of the dimming analog value D4..D0 is allocated
+		 * in the I2C register #0, in the following way:
+		 *
+		 *     +--+--+--+--+--+--+--+--+
+		 *     |EN|D0|D1|D2|D3|D4|XX|XX|
+		 *     +--+--+--+--+--+--+--+--+
+		 */
+		analog_val = DIV_ROUND_UP(ANALOG_MAX_VAL * brightness,
+					  chip->pdata->max_brightness);
+		bits_val = 0;
+		for (i = 0; i <= 5; i++)
+			bits_val += ((analog_val >> i) & 0x01) << (6 - i);
+		ret = regmap_update_bits(chip->regmap, REG_I2C_0,
+					 ANALOG_REG_MASK, bits_val);
+		if (ret)
+			return ret;
+
+		if (brightness > 0)
+			chip->pdata->status = BACKLIGHT_ON;
+		else
+			chip->pdata->status = BACKLIGHT_OFF;
+	}
+
+	return 0;
+}
+
+static const struct backlight_ops mp3309c_bl_ops = {
+	.update_status = mp3309c_bl_update_status,
+};
+
+static int pm3309c_parse_dt_node(struct mp3309c_chip *chip,
+				 struct mp3309c_platform_data *pdata)
+{
+	struct device_node *node = chip->dev->of_node;
+	struct property *prop;
+	int length, ret;
+	unsigned int tmp_value;
+
+	if (!node) {
+		dev_err(chip->dev, "failed to get DT node\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * Dimming mode: the MP3309C provides two dimming control mode:
+	 *
+	 * - PWM mode
+	 * - Analog by I2C control mode (default)
+	 *
+	 * I2C control mode is assumed as default but, if the pwms property is
+	 * found in the backlight node, the mode switches to PWM mode.
+	 */
+	pdata->dimming_mode = DIMMING_ANALOG_I2C;
+	prop = of_find_property(node, "pwms", &length);
+	if (prop) {
+		chip->pwmd = devm_pwm_get(chip->dev, NULL);
+		if (IS_ERR(chip->pwmd))
+			return dev_err_probe(chip->dev, PTR_ERR(chip->pwmd),
+					     "error getting pwm data\n");
+		pdata->dimming_mode = DIMMING_PWM;
+		pwm_apply_args(chip->pwmd);
+	}
+
+	/* Dimming steps (levels): 0 .. max_brightness */
+	ret = of_property_read_u32(node, "max-brightness",
+				   &pdata->max_brightness);
+	if (ret < 0) {
+		dev_err(chip->dev, "failed to get max-brightness from DT\n");
+		return ret;
+	}
+
+	/* Default brightness at startup */
+	ret = of_property_read_u32(node, "default-brightness",
+				   &pdata->default_brightness);
+	if (ret < 0) {
+		dev_err(chip->dev,
+			"failed to get default-brightness from DT\n");
+		return ret;
+	}
+
+	/* Enable GPIO used in I2C dimming mode */
+	if (pdata->dimming_mode == DIMMING_ANALOG_I2C) {
+		chip->enable_gpio = devm_gpiod_get(chip->dev, "enable",
+						   GPIOD_OUT_HIGH);
+		if (IS_ERR(chip->enable_gpio))
+			return dev_err_probe(chip->dev, PTR_ERR(chip->enable_gpio),
+					     "error getting enable gpio\n");
+	}
+
+	/*
+	 * Over-voltage protection (OVP)
+	 *
+	 * This (optional) property values are:
+	 *
+	 *  - 13.5V
+	 *  - 24V
+	 *  - 35.5V (hardware default setting)
+	 *
+	 * If missing, the default value for OVP is 35.5V
+	 */
+	pdata->over_voltage_protection = REG_I2C_1_OVP1;
+	if (!of_property_read_u32(node, "mps,overvoltage-protection-microvolt",
+				  &tmp_value)) {
+		switch (tmp_value) {
+		case 13500000:
+			pdata->over_voltage_protection = 0x00;
+			break;
+		case 24000000:
+			pdata->over_voltage_protection = REG_I2C_1_OVP0;
+			break;
+		case 35500000:
+			pdata->over_voltage_protection = REG_I2C_1_OVP1;
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	/* Synchronous (default) and non-synchronous mode */
+	pdata->sync_mode = true;
+	if (of_property_read_bool(node, "mps,no-sync-mode"))
+		pdata->sync_mode = false;
+
+	return 0;
+}
+
+static int mp3309c_probe(struct i2c_client *client)
+{
+	struct mp3309c_platform_data *pdata = dev_get_platdata(&client->dev);
+	struct mp3309c_chip *chip;
+	struct backlight_properties props;
+	struct pwm_state pwmstate;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(&client->dev, "failed to check i2c functionality\n");
+		return -EOPNOTSUPP;
+	}
+
+	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->dev = &client->dev;
+
+	chip->regmap = devm_regmap_init_i2c(client, &mp3309c_regmap);
+	if (IS_ERR(chip->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(chip->regmap),
+				     "failed to allocate register map\n");
+
+	i2c_set_clientdata(client, chip);
+
+	if (!pdata) {
+		pdata = devm_kzalloc(chip->dev, sizeof(*pdata), GFP_KERNEL);
+		if (!pdata)
+			return -ENOMEM;
+
+		ret = pm3309c_parse_dt_node(chip, pdata);
+		if (ret)
+			return ret;
+	}
+	chip->pdata = pdata;
+
+	/* Backlight properties */
+	props.brightness = pdata->default_brightness;
+	props.max_brightness = pdata->max_brightness;
+	props.scale = BACKLIGHT_SCALE_LINEAR;
+	props.type = BACKLIGHT_RAW;
+	props.power = FB_BLANK_UNBLANK;
+	props.fb_blank = FB_BLANK_UNBLANK;
+	chip->bl = devm_backlight_device_register(chip->dev, "mp3309c",
+						  chip->dev, chip, &mp3309c_bl_ops,
+						  &props);
+	if (IS_ERR(chip->bl))
+		return dev_err_probe(chip->dev, PTR_ERR(chip->bl),
+				     "error registering backlight device\n");
+
+	/* In PWM dimming mode, enable pwm device */
+	if (chip->pdata->dimming_mode == DIMMING_PWM) {
+		pwm_init_state(chip->pwmd, &pwmstate);
+		pwm_set_relative_duty_cycle(&pwmstate,
+					    chip->pdata->default_brightness,
+					    chip->pdata->max_brightness);
+		pwmstate.enabled = true;
+		ret = pwm_apply_state(chip->pwmd, &pwmstate);
+		if (ret)
+			return dev_err_probe(chip->dev, ret,
+					     "error setting pwm device\n");
+	}
+
+	chip->pdata->status = FIRST_POWER_ON;
+	backlight_update_status(chip->bl);
+
+	return 0;
+}
+
+static void mp3309c_remove(struct i2c_client *client)
+{
+	struct mp3309c_chip *chip = i2c_get_clientdata(client);
+	struct backlight_device *bl = chip->bl;
+
+	bl->props.power = FB_BLANK_POWERDOWN;
+	bl->props.brightness = 0;
+	backlight_update_status(chip->bl);
+}
+
+static const struct of_device_id mp3309c_match_table[] = {
+	{ .compatible = "mps,mp3309c", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, mp3309c_match_table);
+
+static const struct i2c_device_id mp3309c_id[] = {
+	{ "mp3309c", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mp3309c_id);
+
+static struct i2c_driver mp3309c_i2c_driver = {
+	.driver	= {
+			.name		= KBUILD_MODNAME,
+			.of_match_table	= mp3309c_match_table,
+	},
+	.probe		= mp3309c_probe,
+	.remove		= mp3309c_remove,
+	.id_table	= mp3309c_id,
+};
+
+module_i2c_driver(mp3309c_i2c_driver);
+
+MODULE_DESCRIPTION("Backlight Driver for MPS MP3309C");
+MODULE_AUTHOR("Flavio Suligoi <f.suligoi@asem.it>");
+MODULE_LICENSE("GPL");