backlight: lp855x_bl: support new LP8555 device

LP8555 is one of the LP855x family devices.

This device needs pre_init_device() and post_init_device() driver
structure.  It's same as LP8557, so the device configuration code is
shared with LP8557.  Backlight outputs are generated from dual DC-DC boost
converters.  It's configurable EPROM settings which are defined in the
platform data.

Driver documentation and device tree bindings are updated.

Signed-off-by: Milo Kim <milo.kim@ti.com>
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 31 insertions, 3 deletions

diff --git a/Documentation/backlight/lp855x-driver.txt b/Documentation/backlight/lp855x-driver.txt
index 1c732f0c6758..01bce243d3d7 100644
--- a/Documentation/backlight/lp855x-driver.txt
+++ b/Documentation/backlight/lp855x-driver.txt
@@ -4,7 +4,8 @@ Kernel driver lp855x
 Backlight driver for LP855x ICs
 
 Supported chips:
-        Texas Instruments LP8550, LP8551, LP8552, LP8553, LP8556 and LP8557
+        Texas Instruments LP8550, LP8551, LP8552, LP8553, LP8555, LP8556 and
+        LP8557
 
 Author: Milo(Woogyom) Kim <milo.kim@ti.com>
 
@@ -24,7 +25,7 @@ Value : pwm based or register based
 
 2) chip_id
 The lp855x chip id.
-Value : lp8550/lp8551/lp8552/lp8553/lp8556/lp8557
+Value : lp8550/lp8551/lp8552/lp8553/lp8555/lp8556/lp8557
 
 Platform data for lp855x
 ------------------------
diff --git a/Documentation/devicetree/bindings/video/backlight/lp855x.txt b/Documentation/devicetree/bindings/video/backlight/lp855x.txt
index 1482103d288f..96e83a56048e 100644
--- a/Documentation/devicetree/bindings/video/backlight/lp855x.txt
+++ b/Documentation/devicetree/bindings/video/backlight/lp855x.txt
@@ -2,7 +2,7 @@ lp855x bindings
 
 Required properties:
   - compatible: "ti,lp8550", "ti,lp8551", "ti,lp8552", "ti,lp8553",
-                "ti,lp8556", "ti,lp8557"
+                "ti,lp8555", "ti,lp8556", "ti,lp8557"
   - reg: I2C slave address (u8)
   - dev-ctrl: Value of DEVICE CONTROL register (u8). It depends on the device.
 
@@ -15,6 +15,33 @@ Optional properties:
 
 Example:
 
+        /* LP8555 */
+        backlight@2c {
+                compatible = "ti,lp8555";
+                reg = <0x2c>;
+
+                dev-ctrl = /bits/ 8 <0x00>;
+                pwm-period = <10000>;
+
+                /* 4V OV, 4 output LED0 string enabled */
+                rom_14h {
+                        rom-addr = /bits/ 8 <0x14>;
+                        rom-val = /bits/ 8 <0xcf>;
+                };
+
+                /* Heavy smoothing, 24ms ramp time step */
+                rom_15h {
+                        rom-addr = /bits/ 8 <0x15>;
+                        rom-val = /bits/ 8 <0xc7>;
+                };
+
+                /* 4 output LED1 string enabled */
+                rom_19h {
+                        rom-addr = /bits/ 8 <0x19>;
+                        rom-val = /bits/ 8 <0x0f>;
+                };
+        };
+
         /* LP8556 */
         backlight@2c {
                 compatible = "ti,lp8556";