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 <[e-mail]>
Signed-off-by: Jingoo Han <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/backlight/lp855x-driver.txt

···
 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 <[e-mail]>
 
···
 
 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
 ------------------------

Documentation/devicetree/bindings/video/backlight/lp855x.txt

···
 
 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.
 
···
   - rom-val: Register value to be updated (u8)
 
 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 {

drivers/video/backlight/Kconfig

···
 	tristate "Backlight driver for TI LP855X"
 	depends on BACKLIGHT_CLASS_DEVICE && I2C
 	help
-	  This supports TI LP8550, LP8551, LP8552, LP8553, LP8556 and LP8557
-	  backlight driver.
+	  This supports TI LP8550, LP8551, LP8552, LP8553, LP8555, LP8556 and
+	  LP8557 backlight driver.
 
 config BACKLIGHT_LP8788
 	tristate "Backlight driver for TI LP8788 MFD"

drivers/video/backlight/lp855x_bl.c

···
 #define LP8556_EPROM_START		0xA0
 #define LP8556_EPROM_END		0xAF
 
-/* LP8557 Registers */
+/* LP8555/7 Registers */
 #define LP8557_BL_CMD			0x00
 #define LP8557_BL_MASK			0x01
 #define LP8557_BL_ON			0x01
 #define LP8557_BL_OFF			0x00
 #define LP8557_BRIGHTNESS_CTRL		0x04
 #define LP8557_CONFIG			0x10
+#define LP8555_EPROM_START		0x10
+#define LP8555_EPROM_END		0x7A
 #define LP8557_EPROM_START		0x10
 #define LP8557_EPROM_END		0x1E
 
···
 		start = LP8556_EPROM_START;
 		end = LP8556_EPROM_END;
 		break;
+	case LP8555:
+		start = LP8555_EPROM_START;
+		end = LP8555_EPROM_END;
+		break;
 	case LP8557:
 		start = LP8557_EPROM_START;
 		end = LP8557_EPROM_END;
···
 	struct lp855x_platform_data *pd = lp->pdata;
 
 	switch (lp->chip_id) {
-	case LP8550 ... LP8556:
+	case LP8550:
+	case LP8551:
+	case LP8552:
+	case LP8553:
+	case LP8556:
 		lp->cfg = &lp855x_dev_cfg;
 		break;
+	case LP8555:
 	case LP8557:
 		lp->cfg = &lp8557_dev_cfg;
 		break;
···
 	{ .compatible = "ti,lp8551", },
 	{ .compatible = "ti,lp8552", },
 	{ .compatible = "ti,lp8553", },
+	{ .compatible = "ti,lp8555", },
 	{ .compatible = "ti,lp8556", },
 	{ .compatible = "ti,lp8557", },
 	{ }
···
 	{"lp8551", LP8551},
 	{"lp8552", LP8552},
 	{"lp8553", LP8553},
+	{"lp8555", LP8555},
 	{"lp8556", LP8556},
 	{"lp8557", LP8557},
 	{ }

include/linux/platform_data/lp855x.h

···
 #define LP8553_PWM_CONFIG	LP8550_PWM_CONFIG
 #define LP8553_I2C_CONFIG	LP8550_I2C_CONFIG
 
+/* CONFIG register - LP8555 */
+#define LP8555_PWM_STANDBY	BIT(7)
+#define LP8555_PWM_FILTER	BIT(6)
+#define LP8555_RELOAD_EPROM	BIT(3)	/* use it if EPROMs should be reset
+					   when the backlight turns on */
+#define LP8555_OFF_OPENLEDS	BIT(2)
+#define LP8555_PWM_CONFIG	LP8555_PWM_ONLY
+#define LP8555_I2C_CONFIG	LP8555_I2C_ONLY
+#define LP8555_COMB1_CONFIG	LP8555_COMBINED1
+#define LP8555_COMB2_CONFIG	LP8555_COMBINED2
+
 /* DEVICE CONTROL register - LP8556 */
 #define LP8556_PWM_CONFIG	(LP8556_PWM_ONLY << BRT_MODE_SHFT)
 #define LP8556_COMB1_CONFIG	(LP8556_COMBINED1 << BRT_MODE_SHFT)
···
 	LP8551,
 	LP8552,
 	LP8553,
+	LP8555,
 	LP8556,
 	LP8557,
 };
···
 enum lp8553_brighntess_source {
 	LP8553_PWM_ONLY = LP8550_PWM_ONLY,
 	LP8553_I2C_ONLY = LP8550_I2C_ONLY,
+};
+
+enum lp8555_brightness_source {
+	LP8555_PWM_ONLY,
+	LP8555_I2C_ONLY,
+	LP8555_COMBINED1,	/* Brightness register with shaped PWM */
+	LP8555_COMBINED2,	/* PWM with shaped brightness register */
 };
 
 enum lp8556_brightness_source {