On Mon, Dec 01, 2025 at 12:53:21PM +0100, Maud Spierings via B4 Relay wrote:
> From: Maud Spierings <[email protected]>
>
> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> with integrated boost controller.
>
> Signed-off-by: Maud Spierings <[email protected]>
> <snip>
> +static int max25014_check_errors(struct max25014 *maxim)
> +{
> + uint32_t val;
> + uint8_t i;
> + int ret;
> +
> + ret = regmap_read(maxim->regmap, MAX25014_OPEN, &val);
> + if (ret)
> + return ret;
> + if (val) {
> + dev_err(&maxim->client->dev, "Open led strings detected on:\n");
> + for (i = 0; i < 4; i++) {
> + if (val & 1 << i)
> + dev_err(&maxim->client->dev, "string %d\n", i +
> 1);
> + }
> + return -EIO;
> + }
> +
> + ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
> + if (ret)
> + return ret;
> + if (val) {
> + dev_err(&maxim->client->dev, "Short to ground detected on:\n");
> + for (i = 0; i < 4; i++) {
> + if (val & 1 << i)
> + dev_err(&maxim->client->dev, "string %d\n", i +
> 1);
> + }
> + return -EIO;
> + }
> +
> + ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
Shouldn't this be MAX25014_SHORT_LED?
> + if (ret)
> + return ret;
> + if (val) {
> + dev_err(&maxim->client->dev, "Shorted led detected on:\n");
> + for (i = 0; i < 4; i++) {
> + if (val & 1 << i)
> + dev_err(&maxim->client->dev, "string %d\n", i +
> 1);
> + }
> + return -EIO;
> + }
> +
> + ret = regmap_read(maxim->regmap, MAX25014_DIAG, &val);
> + if (ret)
> + return ret;
> + /*
> + * The HW_RST bit always starts at 1 after power up.
> + * It is reset on first read, does not indicate an error.
> + */
> + if (val && val != MAX25014_DIAG_HW_RST) {
> + if (val & MAX25014_DIAG_OT)
> + dev_err(&maxim->client->dev,
> + "Overtemperature shutdown\n");
> + if (val & MAX25014_DIAG_OTW)
> + dev_err(&maxim->client->dev,
> + "Chip is getting too hot (>125C)\n");
> + if (val & MAX25014_DIAG_BSTOV)
> + dev_err(&maxim->client->dev,
> + "Boost converter overvoltage\n");
> + if (val & MAX25014_DIAG_BSTUV)
> + dev_err(&maxim->client->dev,
> + "Boost converter undervoltage\n");
> + if (val & MAX25014_DIAG_IREFOOR)
> + dev_err(&maxim->client->dev, "IREF out of range\n");
> + return -EIO;
> + }
> + return 0;
> +}
> +
> +/*
> + * 1. disable unused strings
> + * 2. set dim mode
> + * 3. set setting register
> + * 4. enable the backlight
> + */
> +static int max25014_configure(struct max25014 *maxim, int initial_state)
> +{
> + uint32_t val;
> + int ret;
> +
> + /*
> + * Strings can only be disabled when MAX25014_ISET_ENA == 0, check if
> + * it needs to be changed at all to prevent the backlight flashing when
> + * it is configured correctly by the bootloader
> + */
Attach the comment to the if statement rather than the read.
> + ret = regmap_read(maxim->regmap, MAX25014_DISABLE, &val);
> + if (ret)
> + return ret;
> +
> + if (!((val & MAX25014_DISABLE_DIS_MASK) == maxim->strings_mask)) {
> + if (initial_state == BACKLIGHT_POWER_ON) {
> + ret = regmap_write(maxim->regmap, MAX25014_ISET, 0);
> + if (ret)
> + return ret;
> + }
> + ret = regmap_write(maxim->regmap, MAX25014_DISABLE,
> maxim->strings_mask);
> + if (ret)
> + return ret;
> + }
> +
> + ret = regmap_write(maxim->regmap, MAX25014_IMODE, MAX25014_IMODE_HDIM);
> + if (ret)
> + return ret;
> +
> + ret = regmap_read(maxim->regmap, MAX25014_SETTING, &val);
> + if (ret)
> + return ret;
> +
> + ret = regmap_write(maxim->regmap, MAX25014_SETTING,
> + val & ~MAX25014_SETTING_FPWM);
> + if (ret)
> + return ret;
> +
> + ret = regmap_write(maxim->regmap, MAX25014_ISET,
> + maxim->iset | MAX25014_ISET_ENA |
> + MAX25014_ISET_PSEN);
> + return ret;
> +}
> +
> +static int max25014_update_status(struct backlight_device *bl_dev)
> +{
> + struct max25014 *maxim = bl_get_data(bl_dev);
> + uint32_t reg;
> + int ret;
> +
> + if (backlight_is_blank(maxim->bl))
> + bl_dev->props.brightness = 0;
This isn't right. Why would you change the backlight level just because
it is currently blanked (and sorry I missed this one last time).
> +
> + reg = TON_STEP * bl_dev->props.brightness;
The correct way to honour blanking is just go call
backlight_get_brightness() instead of reading the property directly.
> +
> + /*
> + * 18 bit number lowest, 2 bits in first register,
> + * next lowest 8 in the L register, next 8 in the H register
> + * Seemingly setting the strength of only one string controls all of
> + * them, individual settings don't affect the outcome.
> + */
> +
> + ret = regmap_write(maxim->regmap, MAX25014_TON_1_4_LSB, reg &
> 0b00000011);
> + if (ret != 0)
> + return ret;
> + ret = regmap_write(maxim->regmap, MAX25014_TON1L, (reg >> 2) &
> 0b11111111);
> + if (ret != 0)
> + return ret;
> + return regmap_write(maxim->regmap, MAX25014_TON1H, (reg >> 10) &
> 0b11111111);
> +}
> +
> +static const struct backlight_ops max25014_bl_ops = {
> + .options = BL_CORE_SUSPENDRESUME,
> + .update_status = max25014_update_status,
> +};
> +
> +static int max25014_parse_dt(struct max25014 *maxim,
> + uint32_t *initial_brightness)
> +{
> + struct device *dev = &maxim->client->dev;
> + struct device_node *node = dev->of_node;
> + struct fwnode_handle *child;
> + uint32_t strings[4];
> + int res, i;
> +
> + if (!node)
> + return dev_err_probe(dev, -EINVAL, "no platform data\n");
> +
> + child = device_get_next_child_node(dev, NULL);
> + if (child) {
> + res = fwnode_property_count_u32(child, "led-sources");
> + if (res > 0) {
> + fwnode_property_read_u32_array(child, "led-sources",
> + strings, res);
> +
> + /* set all strings as disabled, then enable those in
> led-sources*/
> + maxim->strings_mask = 0xf;
> + for (i = 0; i < res; i++) {
> + if (strings[i] <= 4)
> + maxim->strings_mask &= ~BIT(strings[i]);
> + }
> + }
> +
> + fwnode_property_read_u32(child, "default-brightness",
> + initial_brightness);
> +
> + fwnode_handle_put(child);
> + }
> +
> + maxim->iset = MAX25014_ISET_DEFAULT_100;
> + of_property_read_u32(node, "maxim,iset", &maxim->iset);
> +
> + if (maxim->iset > 15)
> + return dev_err_probe(dev, -EINVAL,
> + "Invalid iset, should be a value from
> 0-15, entered was %d\n",
> + maxim->iset);
> +
> + if (*initial_brightness > 100)
> + return dev_err_probe(dev, -EINVAL,
> + "Invalid initial brightness, should be a
> value from 0-100, entered was %d\n",
> + *initial_brightness);
> +
> + return 0;
> +}
> +
> +static int max25014_probe(struct i2c_client *cl)
> +{
> + const struct i2c_device_id *id = i2c_client_get_device_id(cl);
> + struct backlight_properties props;
> + uint32_t initial_brightness = 50;
> + struct backlight_device *bl;
> + struct max25014 *maxim;
> + int ret;
> +
> + maxim = devm_kzalloc(&cl->dev, sizeof(struct max25014), GFP_KERNEL);
> + if (!maxim)
> + return -ENOMEM;
> +
> + maxim->client = cl;
> +
> + ret = max25014_parse_dt(maxim, &initial_brightness);
> + if (ret)
> + return ret;
> +
> + maxim->vin = devm_regulator_get(&maxim->client->dev, "power");
> + if (IS_ERR(maxim->vin)) {
> + return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->vin),
> + "failed to get power-supply");
> + }
> +
> + ret = regulator_enable(maxim->vin);
> + if (ret)
> + return dev_err_probe(&maxim->client->dev, ret,
> + "failed to enable power-supply\n");
Can this use devm_regulator_get_enable()?
> +
> + maxim->enable = devm_gpiod_get_optional(&maxim->client->dev, "enable",
> + GPIOD_OUT_HIGH);
> + if (IS_ERR(maxim->enable)) {
> + ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->enable),
> + "failed to get enable gpio\n");
> + goto disable_vin;
> + }
> +
> + /* Datasheet Electrical Characteristics tSTARTUP 2ms */
> + fsleep(2000);
> +
> + maxim->regmap = devm_regmap_init_i2c(cl, &max25014_regmap_config);
> + if (IS_ERR(maxim->regmap)) {
> + ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->regmap),
> + "failed to initialize the i2c regmap\n");
> + goto disable_full;
> + }
> +
> + i2c_set_clientdata(cl, maxim);
> +
> + ret = max25014_check_errors(maxim);
> + if (ret) { /* error is already reported in the above function */
> + goto disable_full;
> + }
> +
> + ret = max25014_initial_power_state(maxim);
> + if (ret < 0) {
> + dev_err_probe(&maxim->client->dev, ret, "Could not get enabled
> state\n");
> + goto disable_full;
> + }
> +
> + memset(&props, 0, sizeof(struct backlight_properties));
> + props.type = BACKLIGHT_PLATFORM;
> + props.max_brightness = MAX_BRIGHTNESS;
> + props.brightness = initial_brightness;
> + props.scale = BACKLIGHT_SCALE_LINEAR;
> + props.power = ret;
> +
> + ret = max25014_configure(maxim, ret);
> + if (ret) {
> + dev_err_probe(&maxim->client->dev, ret, "device config error");
> + goto disable_full;
> + }
> +
> + bl = devm_backlight_device_register(&maxim->client->dev, id->name,
> + &maxim->client->dev, maxim,
> + &max25014_bl_ops, &props);
> + if (IS_ERR(bl)) {
> + ret = dev_err_probe(&maxim->client->dev, PTR_ERR(bl),
> + "failed to register backlight\n");
> + goto disable_full;
> + }
> +
> + maxim->bl = bl;
> +
> + backlight_update_status(maxim->bl);
> +
> + return 0;
> +
> +disable_full:
> + gpiod_set_value_cansleep(maxim->enable, 0);
Why is this needed? It was only ever set by devm_gpiod_get_optional().
> +disable_vin:
> + regulator_disable(maxim->vin);
This is also not needed if you use devm_regulator_get_enable().
> + return ret;
> +}
Daniel.
