backlight: lp855x_bl: support new LP8557 device

LP8557 is one of LP855x family device, but it has different register map
and initialization process.  To support this device, device specific
configuration is done through the lp855x_device_config structure.

Few register definitions are fixed for better readability.
  BRIGHTNESS_CTRL -> LP855X_BRIGHTNESS_CTRL
  DEVICE_CTRL     -> LP855X_DEVICE_CTRL
  EEPROM_START    -> LP855X_EEPROM_START
  EEPROM_END      -> LP855X_EEPROM_END
  EPROM_START     -> LP8556_EPROM_START
  EPROM_END       -> LP8556_EPROM_END

And LP8557 register definitions are added.  New register function,
lp855x_update_bit() is added.

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Acked-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, 73 insertions, 16 deletions

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index a942a2488480..be27b551473f 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -381,7 +381,7 @@ config BACKLIGHT_LP855X
         tristate "Backlight driver for TI LP855X"
         depends on BACKLIGHT_CLASS_DEVICE && I2C
         help
-          This supports TI LP8550, LP8551, LP8552, LP8553 and LP8556
+          This supports TI LP8550, LP8551, LP8552, LP8553, LP8556 and LP8557
           backlight driver.
 
 config BACKLIGHT_OT200
diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
index 050cfbb53667..edd2041b1527 100644
--- a/drivers/video/backlight/lp855x_bl.c
+++ b/drivers/video/backlight/lp855x_bl.c
@@ -17,13 +17,23 @@
 #include <linux/platform_data/lp855x.h>
 #include <linux/pwm.h>
 
-/* Registers */
-#define BRIGHTNESS_CTRL         0x00
-#define DEVICE_CTRL             0x01
-#define EEPROM_START            0xA0
-#define EEPROM_END              0xA7
-#define EPROM_START             0xA0
-#define EPROM_END               0xAF
+/* LP8550/1/2/3/6 Registers */
+#define LP855X_BRIGHTNESS_CTRL          0x00
+#define LP855X_DEVICE_CTRL              0x01
+#define LP855X_EEPROM_START             0xA0
+#define LP855X_EEPROM_END               0xA7
+#define LP8556_EPROM_START              0xA0
+#define LP8556_EPROM_END                0xAF
+
+/* LP8557 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 LP8557_EPROM_START              0x10
+#define LP8557_EPROM_END                0x1E
 
 #define BUF_SIZE                20
 #define DEFAULT_BL_NAME         "lcd-backlight"
@@ -75,6 +85,24 @@ static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
         return i2c_smbus_write_byte_data(lp->client, reg, data);
 }
 
+static int lp855x_update_bit(struct lp855x *lp, u8 reg, u8 mask, u8 data)
+{
+        int ret;
+        u8 tmp;
+
+        ret = i2c_smbus_read_byte_data(lp->client, reg);
+        if (ret < 0) {
+                dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+                return ret;
+        }
+
+        tmp = (u8)ret;
+        tmp &= ~mask;
+        tmp |= data & mask;
+
+        return lp855x_write_byte(lp, reg, tmp);
+}
+
 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
 {
         u8 start, end;
@@ -84,12 +112,16 @@ static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
         case LP8551:
         case LP8552:
         case LP8553:
-                start = EEPROM_START;
-                end = EEPROM_END;
+                start = LP855X_EEPROM_START;
+                end = LP855X_EEPROM_END;
                 break;
         case LP8556:
-                start = EPROM_START;
-                end = EPROM_END;
+                start = LP8556_EPROM_START;
+                end = LP8556_EPROM_END;
+                break;
+        case LP8557:
+                start = LP8557_EPROM_START;
+                end = LP8557_EPROM_END;
                 break;
         default:
                 return false;
@@ -98,9 +130,30 @@ static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
         return (addr >= start && addr <= end);
 }
 
+static int lp8557_bl_off(struct lp855x *lp)
+{
+        /* BL_ON = 0 before updating EPROM settings */
+        return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
+                                LP8557_BL_OFF);
+}
+
+static int lp8557_bl_on(struct lp855x *lp)
+{
+        /* BL_ON = 1 after updating EPROM settings */
+        return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
+                                LP8557_BL_ON);
+}
+
 static struct lp855x_device_config lp855x_dev_cfg = {
-        .reg_brightness = BRIGHTNESS_CTRL,
-        .reg_devicectrl = DEVICE_CTRL,
+        .reg_brightness = LP855X_BRIGHTNESS_CTRL,
+        .reg_devicectrl = LP855X_DEVICE_CTRL,
+};
+
+static struct lp855x_device_config lp8557_dev_cfg = {
+        .reg_brightness = LP8557_BRIGHTNESS_CTRL,
+        .reg_devicectrl = LP8557_CONFIG,
+        .pre_init_device = lp8557_bl_off,
+        .post_init_device = lp8557_bl_on,
 };
 
 /*
@@ -123,6 +176,9 @@ static int lp855x_configure(struct lp855x *lp)
         case LP8550 ... LP8556:
                 lp->cfg = &lp855x_dev_cfg;
                 break;
+        case LP8557:
+                lp->cfg = &lp8557_dev_cfg;
+                break;
         default:
                 return -EINVAL;
         }
@@ -210,7 +266,7 @@ static int lp855x_bl_update_status(struct backlight_device *bl)
 
         } else if (mode == REGISTER_BASED) {
                 u8 val = bl->props.brightness;
-                lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
+                lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
         }
 
         return 0;
@@ -224,7 +280,7 @@ static int lp855x_bl_get_brightness(struct backlight_device *bl)
         if (mode == REGISTER_BASED) {
                 u8 val = 0;
 
-                lp855x_read_byte(lp, BRIGHTNESS_CTRL, &val);
+                lp855x_read_byte(lp, lp->cfg->reg_brightness, &val);
                 bl->props.brightness = val;
         }
 
@@ -376,6 +432,7 @@ static const struct i2c_device_id lp855x_ids[] = {
         {"lp8552", LP8552},
         {"lp8553", LP8553},
         {"lp8556", LP8556},
+        {"lp8557", LP8557},
         { }
 };
 MODULE_DEVICE_TABLE(i2c, lp855x_ids);