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

From: Flavio Suligoi
Date: Mon Oct 23 2023 - 05:11:34 EST

Hi Conor,

...

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

Sorry Conor, what do you mean for "binding patch"? The cover letter of this patch or the
other patch about the dt-bindings for the mp3309c backlight ?

> Thanks,
> Conor.

Thanks,
Flavio.


>
> > 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.ya
> ml
> > +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
> >