Linux Back Light driver

/linux/drvices/leds/leds-lm3530.c

1、prob

static int lm3530_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct lm3530_platform_data *pdata = dev_get_platdata(&client->dev);
struct lm3530_data *drvdata;
int err = 0;

if (pdata == NULL) {
dev_err(&client->dev, "platform data required\n");
return -ENODEV;
}

/* BL mode */
if (pdata->mode > LM3530_BL_MODE_PWM) {
dev_err(&client->dev, "Illegal Mode request\n");
return -EINVAL;
}

if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
dev_err(&client->dev, "I2C_FUNC_I2C not supported\n");
return -EIO;
}

drvdata = devm_kzalloc(&client->dev, sizeof(struct lm3530_data),
GFP_KERNEL);
if (drvdata == NULL)
return -ENOMEM;

drvdata->mode = pdata->mode;
drvdata->client = client;
drvdata->pdata = pdata;
drvdata->brightness = LED_OFF;
drvdata->enable = false;
drvdata->led_dev.name = LM3530_LED_DEV;
drvdata->led_dev.brightness_set = lm3530_brightness_set;
drvdata->led_dev.max_brightness = MAX_BRIGHTNESS;

i2c_set_clientdata(client, drvdata);

drvdata->regulator = devm_regulator_get(&client->dev, "vin");
if (IS_ERR(drvdata->regulator)) {
dev_err(&client->dev, "regulator get failed\n");
err = PTR_ERR(drvdata->regulator);
drvdata->regulator = NULL;
return err;
}

if (drvdata->pdata->brt_val) {
err = lm3530_init_registers(drvdata);
if (err < 0) {
dev_err(&client->dev,
"Register Init failed: %d\n", err);
return err;
}
}
err = led_classdev_register(&client->dev, &drvdata->led_dev);
if (err < 0) {
dev_err(&client->dev, "Register led class failed: %d\n", err);
return err;
}

err = device_create_file(drvdata->led_dev.dev, &dev_attr_mode);
if (err < 0) {
dev_err(&client->dev, "File device creation failed: %d\n", err);
err = -ENODEV;
goto err_create_file;
}

return 0;

err_create_file:
led_classdev_unregister(&drvdata->led_dev);
return err;
}

2、brightness_set

static void lm3530_brightness_set(struct led_classdev *led_cdev,
enum led_brightness brt_val)
{
int err;
struct lm3530_data *drvdata =
container_of(led_cdev, struct lm3530_data, led_dev);
struct lm3530_platform_data *pdata = drvdata->pdata;
struct lm3530_pwm_data *pwm = &pdata->pwm_data;
u8 max_brightness = led_cdev->max_brightness;

switch (drvdata->mode) {
case LM3530_BL_MODE_MANUAL:

if (!drvdata->enable) {
err = lm3530_init_registers(drvdata);
if (err) {
dev_err(&drvdata->client->dev,
"Register Init failed: %d\n", err);
break;
}
}

/* set the brightness in brightness control register*/
err = i2c_smbus_write_byte_data(drvdata->client,
LM3530_BRT_CTRL_REG, brt_val);
if (err)
dev_err(&drvdata->client->dev,
"Unable to set brightness: %d\n", err);
else
drvdata->brightness = brt_val;

if (brt_val == 0)
lm3530_led_disable(drvdata);
break;
case LM3530_BL_MODE_ALS:
break;
case LM3530_BL_MODE_PWM:
if (pwm->pwm_set_intensity)
pwm->pwm_set_intensity(brt_val, max_brightness);
break;
default:
break;
}
}

/linux/drvices/leds/leds-class.c

3、led_classdev_register

/**
* led_classdev_register - register a new object of led_classdev class.
* @parent: The device to register.
* @led_cdev: the led_classdev structure for this device.
*/
int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
{
led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
"%s", led_cdev->name);
if (IS_ERR(led_cdev->dev))
return PTR_ERR(led_cdev->dev);

#ifdef CONFIG_LEDS_TRIGGERS
init_rwsem(&led_cdev->trigger_lock);
#endif
/* add to the list of leds */
down_write(&leds_list_lock);
list_add_tail(&led_cdev->node, &leds_list);
up_write(&leds_list_lock);

if (!led_cdev->max_brightness)
led_cdev->max_brightness = LED_FULL;

led_update_brightness(led_cdev);

INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);

init_timer(&led_cdev->blink_timer);
led_cdev->blink_timer.function = led_timer_function;
led_cdev->blink_timer.data = (unsigned long)led_cdev;

#ifdef CONFIG_LEDS_TRIGGERS
led_trigger_set_default(led_cdev);
#endif

dev_dbg(parent, "Registered led device: %s\n",
led_cdev->name);

return 0;
}
EXPORT_SYMBOL_GPL(led_classdev_register);