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 <[email protected]>
---
MAINTAINERS | 6 +
drivers/video/backlight/Kconfig | 13 +
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/mp3309c_bl.c | 491 +++++++++++++++++++++++++++
4 files changed, 511 insertions(+)
create mode 100644 drivers/video/backlight/mp3309c_bl.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 3be1bdfe8ecc..895c56ff4f1e 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 <[email protected]>
+S: Maintained
+F: Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
+F: drivers/video/backlight/mp3309c_bl.c
+
MR800 AVERMEDIA USB FM RADIO DRIVER
M: Alexey Klimov <[email protected]>
L: [email protected]
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 51387b1ef012..65d0ac9f611d 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -389,6 +389,19 @@ config BACKLIGHT_LM3639
help
This supports TI LM3639 Backlight + 1.5A Flash LED Driver
+config BACKLIGHT_MP3309C
+ tristate "Backlight Driver for MPS MP3309C"
+ depends on I2C
+ select REGMAP_I2C
+ select NEW_LEDS
+ select LEDS_CLASS
+ 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_bl.
+
config BACKLIGHT_LP855X
tristate "Backlight driver for TI LP855X"
depends on I2C && PWM
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index f72e1c3c59e9..c42c5bccc5ac 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-$(CONFIG_BACKLIGHT_MP3309C) += mp3309c_bl.o
obj-$(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_bl.c b/drivers/video/backlight/mp3309c_bl.c
new file mode 100644
index 000000000000..7cb7a542ceca
--- /dev/null
+++ b/drivers/video/backlight/mp3309c_bl.c
@@ -0,0 +1,491 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for MPS MP3309C White LED driver with I2C interface
+ *
+ * Copyright (C) 2023 ASEM Srl
+ * Author: Flavio Suligoi <[email protected]>
+ */
+
+#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>
+#include <linux/workqueue.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 backlight_status {
+ FIRST_POWER_ON,
+ BACKLIGHT_OFF,
+ BACKLIGHT_ON,
+};
+
+enum dimming_mode_value {
+ DIMMING_PWM,
+ DIMMING_ANALOG_I2C,
+};
+
+struct mp3309c_platform_data {
+ u32 max_brightness;
+ u32 brightness;
+ u32 switch_on_delay_ms;
+ u32 switch_off_delay_ms;
+ u32 reset_on_delay_ms;
+ u32 reset_on_length_ms;
+ u8 dimming_mode;
+ u8 reset_pulse_enable;
+ u8 over_voltage_protection;
+
+ unsigned int 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;
+
+ struct delayed_work enable_work;
+ struct delayed_work reset_gpio_work;
+ 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 pm3309c_parse_dt_node(struct mp3309c_chip *chip,
+ struct mp3309c_platform_data *pdata)
+{
+ struct device_node *node = chip->dev->of_node;
+ const char *tmp_string;
+ int ret;
+
+ if (!node) {
+ dev_err(chip->dev, "failed to get DT node\n");
+ return -ENODEV;
+ }
+
+ /*
+ * Dimming mode: the MP3309C provides two dimming methods:
+ *
+ * - PWM mode
+ * - Analog by I2C control mode
+ */
+ ret = of_property_read_string(node, "mps,dimming-mode", &tmp_string);
+ if (ret < 0) {
+ dev_err(chip->dev, "missed dimming-mode in DT\n");
+ return ret;
+ }
+ if (!strcmp(tmp_string, "pwm")) {
+ dev_info(chip->dev, "dimming method: PWM\n");
+ pdata->dimming_mode = DIMMING_PWM;
+ }
+ if (!strcmp(tmp_string, "analog-i2c")) {
+ dev_info(chip->dev, "dimming method: analog by I2C commands\n");
+ pdata->dimming_mode = DIMMING_ANALOG_I2C;
+ }
+
+ /* PWM 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->brightness);
+ if (ret < 0) {
+ dev_err(chip->dev,
+ "failed to get default-brightness from DT\n");
+ return ret;
+ }
+
+ /*
+ * Optional backlight switch-on/off delay
+ *
+ * Note: set 10ms as minimal value for switch-on delay, to stabilize
+ * video data
+ */
+ pdata->switch_on_delay_ms = 50;
+ of_property_read_u32(node, "mps,switch-on-delay-ms",
+ &pdata->switch_on_delay_ms);
+ if (pdata->switch_on_delay_ms < 10) {
+ pdata->switch_on_delay_ms = 10;
+ dev_warn(chip->dev,
+ "switch-on-delay-ms set to 10ms as minimal value\n");
+ }
+ pdata->switch_off_delay_ms = 0;
+ of_property_read_u32(node, "mps,switch-off-delay-ms",
+ &pdata->switch_off_delay_ms);
+
+ /*
+ * Reset: GPIO, initial delay and pulse length
+ *
+ * Use this optional GPIO to reset an external device (LCD panel, video
+ * FPGA, etc) when the backlight is switched on
+ */
+ pdata->reset_pulse_enable = 0;
+ chip->reset_gpio = devm_gpiod_get_optional(chip->dev, "mps,reset",
+ GPIOD_OUT_LOW);
+ if (IS_ERR(chip->reset_gpio)) {
+ ret = PTR_ERR(chip->reset_gpio);
+ dev_err(chip->dev, "error acquiring reset gpio: %d\n", ret);
+ return ret;
+ }
+ if (chip->reset_gpio) {
+ pdata->reset_pulse_enable = 1;
+
+ pdata->reset_on_delay_ms = 10;
+ of_property_read_u32(node, "mps,reset-on-delay-ms",
+ &pdata->reset_on_delay_ms);
+ pdata->reset_on_length_ms = 10;
+ of_property_read_u32(node, "mps,reset-on-length-ms",
+ &pdata->reset_on_length_ms);
+ }
+
+ /*
+ * Over-voltage protection (OVP)
+ *
+ * These (optional) properties are:
+ *
+ * - overvoltage-protection-13v --> OVP point set to 13.5V
+ * - overvoltage-protection-24v --> OVP point set to 24V
+ * - overvoltage-protection-35v --> OVP point set to 35.5V
+ *
+ * If not chosen, the hw default value for OVP is 35.5V
+ */
+ pdata->over_voltage_protection = REG_I2C_1_OVP1;
+ if (of_property_read_bool(node, "mps,overvoltage-protection-13v"))
+ pdata->over_voltage_protection = 0x00;
+ if (of_property_read_bool(node, "mps,overvoltage-protection-24v"))
+ pdata->over_voltage_protection = REG_I2C_1_OVP0;
+ if (of_property_read_bool(node, "mps,overvoltage-protection-35v"))
+ pdata->over_voltage_protection = REG_I2C_1_OVP1;
+
+ return 0;
+}
+
+static int mp3309c_enable_device(struct mp3309c_chip *chip)
+{
+ u8 reg_val = 0; /* Configuration for analog by I2C commands */
+ 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 synchronous mode (fixed for now)
+ * - set overvoltage protection (OVP)
+ */
+ if (chip->pdata->dimming_mode == DIMMING_PWM)
+ reg_val = REG_I2C_1_DIMS;
+ ret = regmap_write(chip->regmap, REG_I2C_1, reg_val | REG_I2C_1_SYNC |
+ chip->pdata->over_voltage_protection);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+/* For delayed backlight enabled */
+static void mp3309c_enable(struct work_struct *work)
+{
+ struct mp3309c_chip *chip = container_of(work, struct mp3309c_chip,
+ enable_work.work);
+ if (mp3309c_enable_device(chip))
+ dev_err(chip->dev, "failed writing I2C register\n");
+}
+
+static void mp3309c_reset_gpio(struct work_struct *work)
+{
+ struct mp3309c_chip *chip = container_of(work, struct mp3309c_chip,
+ reset_gpio_work.work);
+
+ if (chip->reset_gpio) {
+ gpiod_set_value_cansleep(chip->reset_gpio, 0);
+ usleep_range(100, 150);
+ gpiod_set_value_cansleep(chip->reset_gpio, 1);
+ usleep_range(chip->pdata->reset_on_length_ms * 1000,
+ (chip->pdata->reset_on_length_ms * 1000) + 100);
+ gpiod_set_value_cansleep(chip->reset_gpio, 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_init_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;
+ } else {
+ /*
+ * Analog dimming mode by I2C commands
+ *
+ * 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) {
+ switch (chip->pdata->status) {
+ case FIRST_POWER_ON:
+ /*
+ * Only for the first time, wait for the optional
+ * switch-on delay and then enable the device.
+ * Otherwise enable the backlight immediately.
+ */
+ schedule_delayed_work(&chip->enable_work,
+ msecs_to_jiffies(chip->pdata->switch_on_delay_ms));
+ /*
+ * Optional external device GPIO reset, with
+ * delay pulse length
+ */
+ if (chip->pdata->reset_pulse_enable)
+ schedule_delayed_work(&chip->reset_gpio_work,
+ msecs_to_jiffies(chip->pdata->reset_on_delay_ms));
+ break;
+ case BACKLIGHT_OFF:
+ /* Enable the backlight immediately */
+ if (chip->pdata->reset_pulse_enable)
+ cancel_delayed_work(&chip->reset_gpio_work);
+ mp3309c_enable_device(chip);
+ break;
+ }
+
+ chip->pdata->status = BACKLIGHT_ON;
+ } else {
+ /* Wait for the optional switch-off delay */
+ if (chip->pdata->switch_off_delay_ms > 0) {
+ usleep_range(chip->pdata->switch_off_delay_ms * 1000,
+ (chip->pdata->switch_off_delay_ms + 1) *
+ 1000);
+ }
+
+ chip->pdata->status = BACKLIGHT_OFF;
+ }
+
+ return 0;
+}
+
+static const struct backlight_ops mp3309c_bl_ops = {
+ .update_status = mp3309c_bl_update_status,
+};
+
+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;
+ 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(struct mp3309c_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)) {
+ ret = PTR_ERR(chip->regmap);
+ dev_err(&client->dev, "failed to allocate register map\n");
+ return ret;
+ }
+
+ i2c_set_clientdata(client, chip);
+
+ if (!pdata) {
+ pdata = devm_kzalloc(chip->dev,
+ sizeof(struct mp3309c_platform_data),
+ GFP_KERNEL);
+ if (!pdata)
+ return -ENOMEM;
+
+ ret = pm3309c_parse_dt_node(chip, pdata);
+ if (ret) {
+ dev_err(&client->dev, "failed parsing DT node\n");
+ return ret;
+ }
+ }
+ chip->pdata = pdata;
+
+ chip->enable_gpio = devm_gpiod_get_optional(&client->dev, "enable",
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(chip->enable_gpio)) {
+ ret = PTR_ERR(chip->enable_gpio);
+ return ret;
+ }
+
+ /* Backlight */
+ props.type = BACKLIGHT_RAW;
+ props.brightness = pdata->brightness;
+ props.max_brightness = pdata->max_brightness;
+ props.scale = BACKLIGHT_SCALE_LINEAR;
+ chip->bl =
+ devm_backlight_device_register(chip->dev, "mp3309c_bl",
+ chip->dev, chip, &mp3309c_bl_ops,
+ &props);
+ if (IS_ERR(chip->bl)) {
+ dev_err(&client->dev, "failed registering backlight\n");
+ return PTR_ERR(chip->bl);
+ }
+ pdata->status = FIRST_POWER_ON;
+
+ /* Enable PWM, if required */
+ if (pdata->dimming_mode == DIMMING_PWM) {
+ chip->pwmd = devm_pwm_get(chip->dev, NULL);
+ if (IS_ERR(chip->pwmd)) {
+ dev_err(&client->dev, "failed getting pwm device\n");
+ return PTR_ERR(chip->pwmd);
+ }
+ pwm_apply_args(chip->pwmd);
+ }
+
+ /*
+ * Workqueue for delayed backlight enabling
+ */
+ INIT_DELAYED_WORK(&chip->enable_work, mp3309c_enable);
+
+ /*
+ * Workqueue for (optional) external device GPIO reset
+ */
+ if (pdata->reset_pulse_enable) {
+ dev_info(&client->dev, "reset pulse enabled\n");
+ INIT_DELAYED_WORK(&chip->reset_gpio_work, mp3309c_reset_gpio);
+ }
+
+ dev_info(&client->dev, "MP3309C backlight initialized");
+ return 0;
+}
+
+static int mp3309c_backlight_switch_off(struct pwm_device *pwmd)
+{
+ struct pwm_state pwmstate;
+
+ /* Switch-off the backlight */
+ pwm_get_state(pwmd, &pwmstate);
+ pwmstate.duty_cycle = 0;
+ pwmstate.enabled = false;
+ pwm_apply_state(pwmd, &pwmstate);
+
+ return 0;
+}
+
+static void mp3309c_remove(struct i2c_client *client)
+{
+ struct mp3309c_chip *chip = i2c_get_clientdata(client);
+
+ if (chip->pdata->dimming_mode == DIMMING_PWM)
+ mp3309c_backlight_switch_off(chip->pwmd);
+ if (chip->pdata->reset_pulse_enable)
+ cancel_delayed_work(&chip->reset_gpio_work);
+}
+
+static void mp3309c_shutdown(struct i2c_client *client)
+{
+ struct mp3309c_chip *chip = i2c_get_clientdata(client);
+
+ if (chip->pdata->dimming_mode == DIMMING_PWM)
+ mp3309c_backlight_switch_off(chip->pwmd);
+}
+
+static const struct of_device_id mp3309c_match_table[] = {
+ { .compatible = "mps,mp3309c-backlight", },
+ { },
+};
+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 = "mp3309c-backlight",
+ .of_match_table = mp3309c_match_table,
+ },
+ .probe = mp3309c_probe,
+ .remove = mp3309c_remove,
+ .shutdown = mp3309c_shutdown,
+ .id_table = mp3309c_id,
+};
+
+module_i2c_driver(mp3309c_i2c_driver);
+
+MODULE_DESCRIPTION("Backlight Driver for MPS MP3309C");
+MODULE_AUTHOR("Flavio Suligoi <[email protected]>");
+MODULE_LICENSE("GPL");
--
2.34.1
On 29/08/2023 12:15, Flavio Suligoi wrote:
> 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 <[email protected]>
> ---
> MAINTAINERS | 6 +
> drivers/video/backlight/Kconfig | 13 +
> drivers/video/backlight/Makefile | 1 +
> drivers/video/backlight/mp3309c_bl.c | 491 +++++++++++++++++++++++++++
> 4 files changed, 511 insertions(+)
> create mode 100644 drivers/video/backlight/mp3309c_bl.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3be1bdfe8ecc..895c56ff4f1e 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 <[email protected]>
> +S: Maintained
> +F: Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> +F: drivers/video/backlight/mp3309c_bl.c
> +
> MR800 AVERMEDIA USB FM RADIO DRIVER
> M: Alexey Klimov <[email protected]>
> L: [email protected]
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 51387b1ef012..65d0ac9f611d 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -389,6 +389,19 @@ config BACKLIGHT_LM3639
> help
> This supports TI LM3639 Backlight + 1.5A Flash LED Driver
>
> +config BACKLIGHT_MP3309C
Why is this placed between LM and LP entries? Keep things ordered.
> + tristate "Backlight Driver for MPS MP3309C"
> + depends on I2C
> + select REGMAP_I2C
> + select NEW_LEDS
> + select LEDS_CLASS
> + 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_bl.
> +
> config BACKLIGHT_LP855X
> tristate "Backlight driver for TI LP855X"
> depends on I2C && PWM
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index f72e1c3c59e9..c42c5bccc5ac 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-$(CONFIG_BACKLIGHT_MP3309C) += mp3309c_bl.o
> obj-$(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_bl.c b/drivers/video/backlight/mp3309c_bl.c
> new file mode 100644
> index 000000000000..7cb7a542ceca
> --- /dev/null
> +++ b/drivers/video/backlight/mp3309c_bl.c
> @@ -0,0 +1,491 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Driver for MPS MP3309C White LED driver with I2C interface
> + *
> + * Copyright (C) 2023 ASEM Srl
> + * Author: Flavio Suligoi <[email protected]>
> + */
> +
> +#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>
> +#include <linux/workqueue.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 backlight_status {
> + FIRST_POWER_ON,
> + BACKLIGHT_OFF,
> + BACKLIGHT_ON,
> +};
> +
> +enum dimming_mode_value {
> + DIMMING_PWM,
> + DIMMING_ANALOG_I2C,
> +};
> +
> +struct mp3309c_platform_data {
> + u32 max_brightness;
> + u32 brightness;
> + u32 switch_on_delay_ms;
> + u32 switch_off_delay_ms;
> + u32 reset_on_delay_ms;
> + u32 reset_on_length_ms;
> + u8 dimming_mode;
> + u8 reset_pulse_enable;
> + u8 over_voltage_protection;
> +
> + unsigned int 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;
> +
> + struct delayed_work enable_work;
> + struct delayed_work reset_gpio_work;
> + 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 pm3309c_parse_dt_node(struct mp3309c_chip *chip,
> + struct mp3309c_platform_data *pdata)
This should be just before probe function. It is part of probe path.
> +{
> + struct device_node *node = chip->dev->of_node;
> + const char *tmp_string;
> + int ret;
> +
> + if (!node) {
> + dev_err(chip->dev, "failed to get DT node\n");
> + return -ENODEV;
> + }
> +
> + /*
> + * Dimming mode: the MP3309C provides two dimming methods:
> + *
> + * - PWM mode
> + * - Analog by I2C control mode
> + */
> + ret = of_property_read_string(node, "mps,dimming-mode", &tmp_string);
> + if (ret < 0) {
> + dev_err(chip->dev, "missed dimming-mode in DT\n");
> + return ret;
> + }
> + if (!strcmp(tmp_string, "pwm")) {
> + dev_info(chip->dev, "dimming method: PWM\n");
Drop
> + pdata->dimming_mode = DIMMING_PWM;
> + }
> + if (!strcmp(tmp_string, "analog-i2c")) {
> + dev_info(chip->dev, "dimming method: analog by I2C commands\n");
Drop
> + pdata->dimming_mode = DIMMING_ANALOG_I2C;
> + }
> +
> + /* PWM 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->brightness);
> + if (ret < 0) {
> + dev_err(chip->dev,
> + "failed to get default-brightness from DT\n");
> + return ret;
> + }
> +
> + /*
> + * Optional backlight switch-on/off delay
> + *
> + * Note: set 10ms as minimal value for switch-on delay, to stabilize
> + * video data
> + */
> + pdata->switch_on_delay_ms = 50;
> + of_property_read_u32(node, "mps,switch-on-delay-ms",
> + &pdata->switch_on_delay_ms);
> + if (pdata->switch_on_delay_ms < 10) {
> + pdata->switch_on_delay_ms = 10;
You miss constraints in the bindings.
> + dev_warn(chip->dev,
> + "switch-on-delay-ms set to 10ms as minimal value\n");
> + }
> + pdata->switch_off_delay_ms = 0;
> + of_property_read_u32(node, "mps,switch-off-delay-ms",
> + &pdata->switch_off_delay_ms);
> +
> + /*
> + * Reset: GPIO, initial delay and pulse length
> + *
> + * Use this optional GPIO to reset an external device (LCD panel, video
> + * FPGA, etc) when the backlight is switched on
> + */
> + pdata->reset_pulse_enable = 0;
> + chip->reset_gpio = devm_gpiod_get_optional(chip->dev, "mps,reset",
> + GPIOD_OUT_LOW);
> + if (IS_ERR(chip->reset_gpio)) {
> + ret = PTR_ERR(chip->reset_gpio);
> + dev_err(chip->dev, "error acquiring reset gpio: %d\n", ret);
> + return ret;
return dev_err_probe()
> + }
> + if (chip->reset_gpio) {
> + pdata->reset_pulse_enable = 1;
> +
> + pdata->reset_on_delay_ms = 10;
> + of_property_read_u32(node, "mps,reset-on-delay-ms",
> + &pdata->reset_on_delay_ms);
> + pdata->reset_on_length_ms = 10;
> + of_property_read_u32(node, "mps,reset-on-length-ms",
> + &pdata->reset_on_length_ms);
> + }
> +
> + /*
> + * Over-voltage protection (OVP)
> + *
> + * These (optional) properties are:
> + *
> + * - overvoltage-protection-13v --> OVP point set to 13.5V
> + * - overvoltage-protection-24v --> OVP point set to 24V
> + * - overvoltage-protection-35v --> OVP point set to 35.5V
> + *
> + * If not chosen, the hw default value for OVP is 35.5V
> + */
> + pdata->over_voltage_protection = REG_I2C_1_OVP1;
> + if (of_property_read_bool(node, "mps,overvoltage-protection-13v"))
> + pdata->over_voltage_protection = 0x00;
> + if (of_property_read_bool(node, "mps,overvoltage-protection-24v"))
> + pdata->over_voltage_protection = REG_I2C_1_OVP0;
> + if (of_property_read_bool(node, "mps,overvoltage-protection-35v"))
> + pdata->over_voltage_protection = REG_I2C_1_OVP1;
> +
> + return 0;
> +}
> +
...
> +
> +static const struct backlight_ops mp3309c_bl_ops = {
> + .update_status = mp3309c_bl_update_status,
> +};
> +
> +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;
> + 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(struct mp3309c_chip),
sizeof(*)
> + GFP_KERNEL);
> + if (!chip)
> + return -ENOMEM;
> + chip->dev = &client->dev;
> +
> + chip->regmap = devm_regmap_init_i2c(client, &mp3309c_regmap);
> + if (IS_ERR(chip->regmap)) {
> + ret = PTR_ERR(chip->regmap);
> + dev_err(&client->dev, "failed to allocate register map\n");
Are you sure regmap allocation should be followed by error message?
Allocations must not... so if this is not allocation, then syntax is:
return dev_err_probe()
> + return ret;
> + }
> +
> + i2c_set_clientdata(client, chip);
> +
> + if (!pdata) {
> + pdata = devm_kzalloc(chip->dev,
> + sizeof(struct mp3309c_platform_data),
sizeof(*)
> + GFP_KERNEL);
> + if (!pdata)
> + return -ENOMEM;
> +
> + ret = pm3309c_parse_dt_node(chip, pdata);
> + if (ret) {
> + dev_err(&client->dev, "failed parsing DT node\n");
Why do you print errors multiple times? parse_dt_node already does it.
> + return ret;
> + }
> + }
> + chip->pdata = pdata;
> +
> + chip->enable_gpio = devm_gpiod_get_optional(&client->dev, "enable",
> + GPIOD_OUT_HIGH);
> + if (IS_ERR(chip->enable_gpio)) {
> + ret = PTR_ERR(chip->enable_gpio);
> + return ret;
return dev_err_probe()
> + }
> +
> + /* Backlight */
> + props.type = BACKLIGHT_RAW;
> + props.brightness = pdata->brightness;
> + props.max_brightness = pdata->max_brightness;
> + props.scale = BACKLIGHT_SCALE_LINEAR;
> + chip->bl =
> + devm_backlight_device_register(chip->dev, "mp3309c_bl",
> + chip->dev, chip, &mp3309c_bl_ops,
> + &props);
> + if (IS_ERR(chip->bl)) {
> + dev_err(&client->dev, "failed registering backlight\n");
> + return PTR_ERR(chip->bl);
return dev_err_probe()
> + }
> + pdata->status = FIRST_POWER_ON;
> +
> + /* Enable PWM, if required */
> + if (pdata->dimming_mode == DIMMING_PWM) {
> + chip->pwmd = devm_pwm_get(chip->dev, NULL);
> + if (IS_ERR(chip->pwmd)) {
> + dev_err(&client->dev, "failed getting pwm device\n");
> + return PTR_ERR(chip->pwmd);
return dev_err_probe()
> + }
> + pwm_apply_args(chip->pwmd);
> + }
> +
> + /*
> + * Workqueue for delayed backlight enabling
> + */
> + INIT_DELAYED_WORK(&chip->enable_work, mp3309c_enable);
> +
> + /*
> + * Workqueue for (optional) external device GPIO reset
> + */
> + if (pdata->reset_pulse_enable) {
> + dev_info(&client->dev, "reset pulse enabled\n");
Drop, not really helpful.
> + INIT_DELAYED_WORK(&chip->reset_gpio_work, mp3309c_reset_gpio);
> + }
> +
> + dev_info(&client->dev, "MP3309C backlight initialized");
Drop simple tracing messages.
> + return 0;
> +}
> +
> +static int mp3309c_backlight_switch_off(struct pwm_device *pwmd)
> +{
> + struct pwm_state pwmstate;
> +
> + /* Switch-off the backlight */
> + pwm_get_state(pwmd, &pwmstate);
> + pwmstate.duty_cycle = 0;
> + pwmstate.enabled = false;
> + pwm_apply_state(pwmd, &pwmstate);
> +
> + return 0;
> +}
> +
> +static void mp3309c_remove(struct i2c_client *client)
> +{
> + struct mp3309c_chip *chip = i2c_get_clientdata(client);
> +
> + if (chip->pdata->dimming_mode == DIMMING_PWM)
> + mp3309c_backlight_switch_off(chip->pwmd);
> + if (chip->pdata->reset_pulse_enable)
> + cancel_delayed_work(&chip->reset_gpio_work);
> +}
> +
> +static void mp3309c_shutdown(struct i2c_client *client)
> +{
> + struct mp3309c_chip *chip = i2c_get_clientdata(client);
> +
> + if (chip->pdata->dimming_mode == DIMMING_PWM)
> + mp3309c_backlight_switch_off(chip->pwmd);
Why do you need shutdown function?
> +}
> +
> +static const struct of_device_id mp3309c_match_table[] = {
> + { .compatible = "mps,mp3309c-backlight", },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, mp3309c_match_table);
> +
Best regards,
Krzysztof