On Wed, 24 Mar 2021 15:56:30 +0800
Hermes Zhang <chenhui.zhang@xxxxxxxx> wrote:
> From: Hermes Zhang <chenhuiz@xxxxxxxx>
>
> Introduce a new multiple GPIOs LED driver. This LED will made of
> multiple GPIOs (up to 8) and will map different brightness to different
> GPIOs states which defined in dts file.
I wonder how many boards have such LEDs.
Also if it wouldn't be better to expand the original leds-gpio driver.
Probably depends on how much larger would such expansion make the
leds-gpio driver.
> +#include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/slab.h>
Why do you include slab.h?
> +
> +#define MAX_GPIO_NUM 8
> +
> +struct multi_gpio_led_priv {
> + struct led_classdev cdev;
> +
> + struct gpio_descs *gpios;
> +
> + u8 *states;
> + int nr_states;
> +};
Use flexible array members. Allocate with
devm_kzalloc(dev, struct_size(priv, states, priv->nr_states),
GFP_KERNEL)
> +
> +
> +static void multi_gpio_led_set(struct led_classdev *led_cdev,
> + enum led_brightness value)
> +{
> + struct multi_gpio_led_priv *priv;
> + int idx;
> +
> + DECLARE_BITMAP(values, MAX_GPIO_NUM);
> +
> + priv = container_of(led_cdev, struct multi_gpio_led_priv, cdev);
> +
> + idx = (value - LED_OFF) * priv->nr_states / (LED_FULL + 1);
LED_FULL / LED_OFF are deprecated, don't use them.
> +
> + values[0] = priv->states[idx];
> +
> + gpiod_set_array_value(priv->gpios->ndescs, priv->gpios->desc,
> + priv->gpios->info, values);
> +}
> +
> +static int multi_gpio_led_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *node = dev->of_node;
> + struct multi_gpio_led_priv *priv = NULL;
> + int ret;
> + const char *state = NULL;
> + struct led_init_data init_data = {};
> +
> + priv = devm_kzalloc(dev, sizeof(struct multi_gpio_led_priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + priv->gpios = devm_gpiod_get_array(dev, "led", GPIOD_OUT_LOW);
> + if (IS_ERR(priv->gpios))
> + return PTR_ERR(priv->gpios);
> +
> + if (priv->gpios->ndescs >= MAX_GPIO_NUM) {
> + dev_err(dev, "Too many GPIOs\n");
> + return -EINVAL;
> + }
> +
> + ret = of_property_count_u8_elems(node, "led-states");
> + if (ret < 0)
> + return ret;
> +
> + priv->nr_states = ret;
> + priv->states = devm_kzalloc(dev, sizeof(*priv->states) * priv->nr_states, GFP_KERNEL);
> + if (!priv->states)
> + return -ENOMEM;
> +
> + ret = of_property_read_u8_array(node, "led-states", priv->states, priv->nr_states);
> + if (ret)
> + return ret;
> +
> + priv->cdev.max_brightness = LED_FULL;
???? max_brightness is not 255 (= LED_FULL). max_brightness must be
derived from the led-states property.
> + priv->cdev.default_trigger = of_get_property(node, "linux,default-trigger", NULL);
> + priv->cdev.brightness_set = multi_gpio_led_set;
> +
> + init_data.fwnode = of_fwnode_handle(node);
> +
> + ret = devm_led_classdev_register_ext(dev, &priv->cdev, &init_data);
> + if (ret < 0)
> + return ret;
> +
> + of_property_read_string(node, "default-state", &state);
> + if (!strcmp(state, "on"))
> + multi_gpio_led_set(&priv->cdev, LED_FULL);
> + else
> + multi_gpio_led_set(&priv->cdev, LED_OFF);
Again LED_FULL and LED_OFF...
What about default-state = "keep" ?
Hermes, do you actually have a device that controls LEDs this way? How
many brightness options do they have?
Also I think this functionality could be easily incorporated into the
existing leds-gpio driver, instead of creating new driver.
Moreover your driver can control only one LED, so it needs to be
probed multiple times for multiple LEDs. Meanwhile the leds-gpio driver
can register multiple LEDs in one probe...
Marek
