backlight: new backlight driver for LP855x devices

[karo-tx-linux.git] / Documentation / backlight / lp855x-driver.txt

diff --git a/Documentation/backlight/lp855x-driver.txt b/Documentation/backlight/lp855x-driver.txt
new file mode 100644 (file)
index 0000000..f5e4caa
--- /dev/null
+++ b/Documentation/backlight/lp855x-driver.txt
@@ -0,0 +1,78 @@
+Kernel driver lp855x
+====================
+
+Backlight driver for LP855x ICs
+
+Supported chips:
+       Texas Instruments LP8550, LP8551, LP8552, LP8553 and LP8556
+
+Author: Milo(Woogyom) Kim <milo.kim@ti.com>
+
+Description
+-----------
+
+* Brightness control
+
+Brightness can be controlled by the pwm input or the i2c command.
+The lp855x driver supports both cases.
+
+* Device attributes
+
+1) bl_ctl_mode
+Backlight control mode.
+Value : pwm based or register based
+
+2) chip_id
+The lp855x chip id.
+Value : lp8550/lp8551/lp8552/lp8553/lp8556
+
+Platform data for lp855x
+------------------------
+
+For supporting platform specific data, the lp855x platform data can be used.
+
+* name : Backlight driver name. If it is not defined, default name is set.
+* mode : Brightness control mode. PWM or register based.
+* device_control : Value of DEVICE CONTROL register.
+* initial_brightness : Initial value of backlight brightness.
+* pwm_data : Platform specific pwm generation functions.
+            Only valid when brightness is pwm input mode.
+            Functions should be implemented by PWM driver.
+            - pwm_set_intensity() : set duty of PWM
+            - pwm_get_intensity() : get current duty of PWM
+* load_new_rom_data :
+       0 : use default configuration data
+       1 : update values of eeprom or eprom registers on loading driver
+* size_program : Total size of lp855x_rom_data.
+* rom_data : List of new eeprom/eprom registers.
+
+example 1) lp8552 platform data : i2c register mode with new eeprom data
+
+#define EEPROM_A5_ADDR 0xA5
+#define EEPROM_A5_VAL  0x4f    /* EN_VSYNC=0 */
+
+static struct lp855x_rom_data lp8552_eeprom_arr[] = {
+       {EEPROM_A5_ADDR, EEPROM_A5_VAL},
+};
+
+static struct lp855x_platform_data lp8552_pdata = {
+       .name = "lcd-bl",
+       .mode = REGISTER_BASED,
+       .device_control = I2C_CONFIG(LP8552),
+       .initial_brightness = INITIAL_BRT,
+       .load_new_rom_data = 1,
+       .size_program = ARRAY_SIZE(lp8552_eeprom_arr),
+       .rom_data = lp8552_eeprom_arr,
+};
+
+example 2) lp8556 platform data : pwm input mode with default rom data
+
+static struct lp855x_platform_data lp8556_pdata = {
+       .mode = PWM_BASED,
+       .device_control = PWM_CONFIG(LP8556),
+       .initial_brightness = INITIAL_BRT,
+       .pwm_data = {
+                    .pwm_set_intensity = platform_pwm_set_intensity,
+                    .pwm_get_intensity = platform_pwm_get_intensity,
+                    },
+};