leds: backlight: add PWM and Bright modes

lp8550 has PWM and Bright modes to control backlight.
remove redundant writes to device ctrl config.

Change-Id: Ida6f405fd174a87965f9d2daabbdc6b236f30245
Signed-off-by: makarand.karvekar <makarand.karvekar@motorola.com>

diff --git a/drivers/leds/leds-lp8550.c b/drivers/leds/leds-lp8550.c
index d2d5cc0b3b5287c0052b612d7729dd15b9dde92f..f99add9130cce96dea21683547e3e9fd2ade3e76 100755 (executable)
--- a/drivers/leds/leds-lp8550.c
+++ b/drivers/leds/leds-lp8550.c
@@ -41,6 +41,9 @@
 #define LP8550_TEMP_MSB                0x05
 #define LP8550_TEMP_LSB                0x06
 
+#define LP8550_BRT_MODE_PWM    0x02
+#define LP8550_BRT_MODE_BRIGHT 0x04
+
 /* EEPROM Register address */
 #define LP8550_EEPROM_CTRL     0x72
 #define LP8550_EEPROM_A0       0xa0
@@ -60,6 +63,7 @@ struct lp8550_data {
        struct lp8550_platform_data *led_pdata;
        uint8_t last_requested_brightness;
        int brightness;
+       atomic_t enabled;
 };
 
 #ifdef DEBUG
@@ -191,7 +195,7 @@ static int ld_lp8550_init_registers(struct lp8550_data *led_data)
        }
 
        if (lp8550_write_reg(led_data, LP8550_DEVICE_CTRL,
-               led_data->led_pdata->dev_ctrl_config)) {
+               (led_data->led_pdata->dev_ctrl_config | 0x01))) {
                pr_err("%s:Register initialization failed\n", __func__);
                return -EINVAL;
        }
@@ -236,13 +240,29 @@ static void lp8550_brightness_write(struct lp8550_data *led_data)
                        pr_err("%s:writing failed while setting brightness:%d\n",
                                __func__, error);
                }
+               atomic_set(&led_data->enabled, 0);
        } else {
-               if (lp8550_write_reg(led_data, LP8550_DEVICE_CTRL,
-                               led_data->led_pdata->dev_ctrl_config | 0x01)) {
-                       pr_err("%s:writing failed while setting brightness:%d\n",
+               if (!atomic_cmpxchg(&led_data->enabled, 0, 1)) {
+                       if (lp8550_write_reg(led_data, LP8550_DEVICE_CTRL,
+                               led_data->led_pdata->dev_ctrl_config | 0x01))
+                               pr_err("%s:writing failed while setting brightness:%d\n",
+                                       __func__, error);
+                       else
+                               atomic_set(&led_data->enabled, 1);
+               }
+
+               if (led_data->led_pdata->dev_ctrl_config ==
+                        LP8550_BRT_MODE_BRIGHT) {
+                       if (lp8550_write_reg(led_data, LP8550_BRIGHTNESS_CTRL,
+                                brightness))
+                               pr_err("%s:Failed to set brightness:%d\n",
                                __func__, error);
                }
-               if (lp8550_write_reg(led_data, LP8550_BRIGHTNESS_CTRL, brightness)) {
+
+               if (led_data->led_pdata->dev_ctrl_config ==
+                        LP8550_BRT_MODE_PWM) {
+                       if (lp8550_write_reg(led_data, LP8550_EEPROM_A0,
+                                brightness))
                                pr_err("%s:Failed to set brightness:%d\n",
                                __func__, error);
                }
@@ -352,8 +372,14 @@ static int ld_lp8550_probe(struct i2c_client *client,
                goto err_reg_init_failed;
        }
 
-       error = lp8550_write_reg(led_data, LP8550_BRIGHTNESS_CTRL,
+       if (led_data->led_pdata->dev_ctrl_config == LP8550_BRT_MODE_BRIGHT) {
+               error = lp8550_write_reg(led_data, LP8550_BRIGHTNESS_CTRL,
+                                pdata->power_up_brightness);
+       } else if (led_data->led_pdata->dev_ctrl_config == LP8550_BRT_MODE_PWM) {
+               error = lp8550_write_reg(led_data, LP8550_EEPROM_A0,
                                 pdata->power_up_brightness);
+       }
+
        if (error) {
                pr_err("%s:Setting power up brightness failed %d\n",
                       __func__, error);
@@ -361,6 +387,8 @@ static int ld_lp8550_probe(struct i2c_client *client,
                goto err_reg_init_failed;
        }
 
+       atomic_set(&led_data->enabled, 0);
+
        INIT_WORK(&led_data->wq, lp8550_brightness_work);
 
        error = led_classdev_register((struct device *) &client->dev,