docs: lp855x-driver.txt: convert to ReST and move to kernel-api

[linux-2.6-block.git] / Documentation / backlight / lp855x-driver.rst

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+
+====================
+Kernel driver lp855x
+====================
+
+Backlight driver for LP855x ICs
+
+Supported chips:
+
+       Texas Instruments LP8550, LP8551, LP8552, LP8553, LP8555, LP8556 and
+       LP8557
+
+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/lp8555/lp8556/lp8557
+
+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.
+* device_control:
+       Value of DEVICE CONTROL register.
+* initial_brightness:
+       Initial value of backlight brightness.
+* period_ns:
+       Platform specific PWM period value. unit is nano.
+       Only valid when brightness is pwm input mode.
+* size_program:
+       Total size of lp855x_rom_data.
+* rom_data:
+       List of new eeprom/eprom registers.
+
+Examples
+========
+
+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",
+       .device_control = I2C_CONFIG(LP8552),
+       .initial_brightness = INITIAL_BRT,
+       .size_program = ARRAY_SIZE(lp8552_eeprom_arr),
+       .rom_data = lp8552_eeprom_arr,
+    };
+
+2) lp8556 platform data: pwm input mode with default rom data::
+
+    static struct lp855x_platform_data lp8556_pdata = {
+       .device_control = PWM_CONFIG(LP8556),
+       .initial_brightness = INITIAL_BRT,
+       .period_ns = 1000000,
+    };