Re: [PATCH 1/2] leds: tlc5928: Driver for the TI 16 Channel spi LED driver

[Christophe JAILLET <christophe.jaillet@wanadoo.fr>]

Le 26/03/2025 à 16:35, Corentin Guillevic a écrit :
> The TLC59928 is an SPI-connected bus controlled 16-channel LED driver.
> A single 16-bit register handles the whole LEDs. Following a write, a
> latch GPIO applies the new LED configuration. An "enable" GPIO (blank
> in the TLC59928 datasheet) turns off the whole LEDs when active/high.
> 
> This driver is able to handle a daisy-chain case, so when several
> TLC59928 controllers are connected in serie.
> 
> Signed-off-by: Corentin Guillevic <corentin.guillevic@smile.fr>
> ---

...

> +static int
> +tlc5928_set_ledout(struct tlc5928_led *led, bool val)
> +{
> +	struct tlc5928_chip *chip;
> +	struct tlc5928_chip *chip_owner = led->chip;
> +	struct tlc5928_priv *priv = chip_owner->priv;
> +	int ret;
> +
> +	mutex_lock(&priv->lock);
> +
> +	if (val)
> +		chip_owner->leds_state |= (1 << led->led_no);
> +	else
> +		chip_owner->leds_state &= ~(1 << led->led_no);
> +
> +	list_for_each_entry_reverse(chip, &priv->chips_list, list) {
> +		u16 leds_state = cpu_to_be16(chip->leds_state);
> +
> +		ret = spi_write(priv->spi, &(leds_state), sizeof(leds_state));
> +
> +		if (ret)

Missing unlock.
Or use guard()?

> +			return ret;
> +	}
> +
> +	gpiod_set_value(priv->latch_gpio, 0);
> +	udelay(1);
> +	gpiod_set_value(priv->latch_gpio, 1);
> +
> +	mutex_unlock(&priv->lock);
> +
> +	return 0;
> +}
> +
> +static int
> +tlc5928_brightness_set(struct led_classdev *led_cdev,
> +			enum led_brightness brightness)
> +{
> +	struct tlc5928_led *led = ldev_to_led(led_cdev);
> +
> +	/* TLC5928 only allows on/off, no brightness */
> +	return tlc5928_set_ledout(led, !!brightness);
> +}
> +
> +static const struct of_device_id of_tlc5928_leds_match[] __maybe_unused = {
> +	{ .compatible = "ti,tlc5928" },
> +	{},

Unneeded trailing ,

> +};
> +MODULE_DEVICE_TABLE(of, of_tlc5928_leds_match);
> +
> +static int tlc5928_probe_chip_dt(struct device *dev, struct device_node *node,
> +		struct tlc5928_chip *chip)
> +{
> +	struct device_node *child;
> +	int count, err, reg;
> +
> +	count = of_get_available_child_count(node);
> +	if (!count)
> +		return -EINVAL;
> +
> +	chip->leds_state = 0;
> +
> +	for_each_available_child_of_node(node, child) {

for_each_available_child_of_node_scoped()?

> +		struct tlc5928_led *led;
> +		struct led_init_data init_data = {};
> +
> +		init_data.fwnode = of_fwnode_handle(child);
> +
> +		err = of_property_read_u32(child, "reg", &reg);
> +		if (err) {
> +			dev_err(dev, "%pOF: failed to read reg\n", child);
> +			of_node_put(child);
> +			return err;
> +		}
> +
> +		if (reg < 0 || reg >= TLC5928_MAX_LEDS ||
> +				chip->leds[reg].active) {
> +			of_node_put(child);
> +			return -EINVAL;
> +		}
> +
> +		led = &chip->leds[reg];
> +
> +		led->active = true;
> +		led->chip = chip;
> +		led->led_no = reg;
> +		led->ldev.brightness_set_blocking = tlc5928_brightness_set;
> +		err = devm_led_classdev_register_ext(dev, &led->ldev,
> +							 &init_data);
> +		if (err < 0) {
> +			of_node_put(child);
> +			dev_err(dev, "Failed to register LED for node %pfw\n",
> +				init_data.fwnode);
> +			return err;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int tlc5928_probe(struct spi_device *spi)
> +{
> +	struct device_node *node, *child;
> +	struct device *dev = &spi->dev;
> +	struct list_head *pos;
> +	struct tlc5928_chip *chip;
> +	struct tlc5928_priv *priv;
> +	int count, err, i;
> +
> +	node = dev_of_node(dev);
> +	if (!node)
> +		return -ENODEV;
> +
> +	count = of_get_available_child_count(node);
> +	if (!count)
> +		return -EINVAL;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->spi = spi;
> +	priv->latch_gpio = devm_gpiod_get(dev, "latch", GPIOD_OUT_HIGH);
> +	if (IS_ERR(priv->latch_gpio))
> +		return dev_err_probe(dev, PTR_ERR(priv->latch_gpio),
> +				     "Failed to get latch GPIO\n");
> +
> +	mutex_init(&priv->lock);

Maybe:
err = devm_mutex_init(...);
if (err)
	return err;

?

> +	INIT_LIST_HEAD(&priv->chips_list);
> +
> +	i = 0;
> +	for_each_available_child_of_node(node, child) {
> +		chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
> +		if (!chip)
> +			return -ENOMEM;
> +
> +		list_add_tail(&chip->list, &priv->chips_list);
> +		chip->priv = priv;
> +		chip->enable_gpio = devm_gpiod_get_index_optional(dev, "enable", i,
> +				GPIOD_OUT_HIGH);
> +		if (IS_ERR(chip->enable_gpio)) {
> +			dev_err(dev, "Error getting enable GPIO %i property: %ld\n", i,
> +					PTR_ERR(chip->enable_gpio));
> +			return PTR_ERR(chip->enable_gpio);
> +		}
> +
> +		err = tlc5928_probe_chip_dt(dev, child, chip);
> +		if (err)
> +			return err;
> +
> +		i++;
> +	}
> +
> +	list_for_each(pos, &priv->chips_list) {

list_for_each_entry()?

> +		chip = container_of(pos, struct tlc5928_chip, list);
> +		if (chip->enable_gpio)
> +			gpiod_set_value(chip->enable_gpio, 0);
> +	}
> +
> +	spi_set_drvdata(spi, priv);
> +
> +	return 0;
> +}
> +
> +static int tlc5928_remove(struct spi_device *spi)
> +{
> +	struct list_head *pos;
> +	struct tlc5928_priv *priv = spi_get_drvdata(spi);
> +	int i;
> +
> +	list_for_each(pos, &priv->chips_list) {

list_for_each_entry()?

> +		struct tlc5928_chip *chip = container_of(pos, struct tlc5928_chip,
> +				list);
> +
> +		for (i = 0; i < TLC5928_MAX_LEDS; i++) {
> +			if (chip->leds[i].active)
> +				devm_led_classdev_unregister(&spi->dev,
> +					     &chip->leds[i].ldev);

Why is it needed?
devm_led_classdev_register_ext() was used.

> +		}
> +
> +		if (chip->enable_gpio) {
> +			gpiod_set_value(chip->enable_gpio, 1);
> +			gpiod_put(chip->enable_gpio);

Why is it needed?
devm_gpiod_get_index_optional() was used.

> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct spi_device_id tlc5928_id[] = {
> +	{ "tlc5928" },
> +	{},

Unneeded trailing ,

> +};
> +MODULE_DEVICE_TABLE(spi, tlc5928_id);

...

CJ