Re: [PATCH v5] backlight: mp3309c: Add support for MPS MP3309C

From: Conor Dooley
Date: Fri Oct 20 2023 - 11:57:02 EST

On Fri, Oct 20, 2023 at 03:54:34PM +0200, 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 <f.suligoi@xxxxxxx>
> ---
>
> v5:
> - checked and resend for updated kernel 6.6.0-rc1

Why is this v5 patch attached to a 1 patch "series" that only purports
to contain a binding patch?

Thanks,
Conor.

> v4:
> - add brightness-levels property
> - force fixed 32 brightness levels (0..31) in analog-i2c dimming mode
> - remove useless irq and reset_gpio from mp3309c_chip structure
> 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 | 7 +
> drivers/video/backlight/Kconfig | 11 +
> drivers/video/backlight/Makefile | 1 +
> drivers/video/backlight/mp3309c.c | 443 ++++++++++++++++++++++++++++++
> 4 files changed, 462 insertions(+)
> create mode 100644 drivers/video/backlight/mp3309c.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 90f13281d297..3d23b869e2aa 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -14474,6 +14474,13 @@ S: Maintained
> F: Documentation/driver-api/tty/moxa-smartio.rst
> F: drivers/tty/mxser.*
>
> +MP3309C BACKLIGHT DRIVER
> +M: Flavio Suligoi <f.suligoi@xxxxxxx>
> +L: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> +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@xxxxxxxxx>
> L: linux-media@xxxxxxxxxxxxxxx
> 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..3fe4469ef43f
> --- /dev/null
> +++ b/drivers/video/backlight/mp3309c.c
> @@ -0,0 +1,443 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Driver for MPS MP3309C White LED driver with I2C interface
> + *
> + * This driver support both analog (by I2C commands) and PWM dimming control
> + * modes.
> + *
> + * Copyright (C) 2023 ASEM Srl
> + * Author: Flavio Suligoi <f.suligoi@xxxxxxx>
> + *
> + * Based on pwm_bl.c
> + */
> +
> +#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_I2C_NUM_LEVELS 32 /* 0..31 */
> +#define ANALOG_I2C_REG_MASK 0x7c
> +
> +#define MP3309C_PWM_DEFAULT_NUM_LEVELS 256 /* 0..255 */
> +
> +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 {
> + unsigned int max_brightness;
> + unsigned int default_brightness;
> + unsigned int *levels;
> + 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;
> +};
> +
> +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 control mode
> + */
> + pwm_get_state(chip->pwmd, &pwmstate);
> + pwm_set_relative_duty_cycle(&pwmstate,
> + chip->pdata->levels[brightness],
> + chip->pdata->levels[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 (by I2C command) control 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 (fixed dimming range 0..31)
> + *
> + * 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 = 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_I2C_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_pwms, *prop_levels;
> + int length = 0;
> + int ret, i;
> + unsigned int num_levels, 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_pwms = of_find_property(node, "pwms", &length);
> + if (prop_pwms) {
> + 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);
> + }
> +
> + /*
> + * In I2C control mode the dimming levels (0..31) are fixed by the
> + * hardware, while in PWM control mode they can be chosen by the user,
> + * to allow nonlinear mappings.
> + */
> + if (pdata->dimming_mode == DIMMING_ANALOG_I2C) {
> + /*
> + * Analog (by I2C commands) control mode: fixed 0..31 brightness
> + * levels
> + */
> + num_levels = ANALOG_I2C_NUM_LEVELS;
> +
> + /* Enable GPIO used in I2C dimming mode only */
> + 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");
> + } else {
> + /*
> + * PWM control mode: check for brightness level in DT
> + */
> + prop_levels = of_find_property(node, "brightness-levels",
> + &length);
> + if (prop_levels) {
> + /* Read brightness levels from DT */
> + num_levels = length / sizeof(u32);
> + if (num_levels < 2)
> + return -EINVAL;
> + } else {
> + /* Use default brightness levels */
> + num_levels = MP3309C_PWM_DEFAULT_NUM_LEVELS;
> + }
> + }
> +
> + /* Fill brightness levels array */
> + pdata->levels = devm_kcalloc(chip->dev, num_levels,
> + sizeof(*pdata->levels), GFP_KERNEL);
> + if (!pdata->levels)
> + return -ENOMEM;
> + if (prop_levels) {
> + ret = of_property_read_u32_array(node, "brightness-levels",
> + pdata->levels,
> + num_levels);
> + if (ret < 0)
> + return ret;
> + } else {
> + for (i = 0; i < num_levels; i++)
> + pdata->levels[i] = i;
> + }
> +
> + pdata->max_brightness = num_levels - 1;
> +
> + ret = of_property_read_u32(node, "default-brightness",
> + &pdata->default_brightness);
> + if (ret)
> + pdata->default_brightness = pdata->max_brightness;
> + if (pdata->default_brightness > pdata->max_brightness) {
> + dev_err(chip->dev,
> + "default brightness exceeds max brightness\n");
> + pdata->default_brightness = pdata->max_brightness;
> + }
> +
> + /*
> + * 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@xxxxxxx>");
> +MODULE_LICENSE("GPL");
> --
> 2.34.1
>

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