backlight: new backlight driver for LP855x devices
THis driver supports TI LP8550/LP8551/LP8552/LP8553/LP8556 backlight
devices.
The brightness can be controlled by the I2C or PWM input. The lp855x
driver provides both modes. For the PWM control, pwm-specific functions
can be defined in the platform data. And some information can be read
via the sysfs(lp855x device attributes).
For details, please refer to Documentation/backlight/lp855x-driver.txt.
[axel.lin@gmail.com: add missing mutex_unlock in lp855x_read_byte() error path]
[axel.lin@gmail.com: check platform data in lp855x_probe()]
[axel.lin@gmail.com: small cleanups]
[dan.carpenter@oracle.com: silence a compiler warning]
[axel.lin@gmail.com: use id->driver_data to differentiate lp855x chips]
[akpm@linux-foundation.org: simplify boolean return expression]
Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/backlight/lp855x-driver.txt b/Documentation/backlight/lp855x-driver.txt
new file mode 100644
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,
+ },
+};