Merge branch 'pandora-27-omap1' into rev2

[pandora-kernel.git] / drivers / video / backlight / twl4030_pwm0_bl.c

diff --git a/drivers/video/backlight/twl4030_pwm0_bl.c b/drivers/video/backlight/twl4030_pwm0_bl.c
index 2f15541..6904685 100644 (file)
--- a/drivers/video/backlight/twl4030_pwm0_bl.c
+++ b/drivers/video/backlight/twl4030_pwm0_bl.c
@@ -1,7 +1,9 @@
 /*
- * Backlight driver for TWL4030 PWM0.
+ * Backlight driver for TWL4030 PWM0 -> TPS61161 combo.
  * Based on pwm_bl.c
  *
+ * Author: Gražvydas Ignotas <notasas@gmail.com>
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -10,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/platform_device.h>
+#include <linux/delay.h>
 #include <linux/fb.h>
 #include <linux/backlight.h>
 #include <linux/i2c/twl4030.h>
@@ -21,11 +24,32 @@
 #define TWL_INTBR_GPBR1        0x0c
 #define TWL_INTBR_PMBR1        0x0d
 
+#define PWM0_CLK_ENABLE        1
+#define PWM0_ENABLE    4
+
+/* range accepted by hardware */
+#define MIN_VALUE 9
+#define MAX_VALUE 63
+#define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
+
 static int old_brightness;
 
+static void pwm0_disable(void)
+{
+       u8 r;
+
+       /* first disable PWM0 output, then clock */
+       twl4030_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
+       r &= ~PWM0_ENABLE;
+       twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+       r &= ~PWM0_CLK_ENABLE;
+       twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+}
+
 static int pwm0_backlight_update_status(struct backlight_device *bl)
 {
        int brightness = bl->props.brightness;
+       u8 r;
 
        if (bl->props.power != FB_BLANK_UNBLANK)
                brightness = 0;
@@ -35,31 +59,37 @@ static int pwm0_backlight_update_status(struct backlight_device *bl)
                brightness = 0;
        */
 
-       if ((unsigned)brightness > 57)
-               brightness = 57;
+       if ((unsigned int)brightness > MAX_USER_VALUE)
+               brightness = MAX_USER_VALUE;
 
        if (brightness == 0) {
-               if (old_brightness != 0) {
-                       /* set OFF time to max,
-                        * then disable PWM0 output and clock */
-                       twl4030_i2c_write_u8(TWL4030_MODULE_PWM0, 0x3f,
-                                               TWL_PWM0_OFF);
-                       /* 0x49 0x91 */
-                       twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, 0x01,
-                                               TWL_INTBR_GPBR1);
-                       twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, 0x00,
-                                               TWL_INTBR_GPBR1);
-               }
+               if (old_brightness != 0)
+                       pwm0_disable();
 
                goto done;
        }
 
-       if (old_brightness == 0)
-               /* turn PWM0 output and clock on */
-               twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, 0x05,
-                                       TWL_INTBR_GPBR1);
+       if (old_brightness == 0) {
+               /* set PWM duty cycle to max. TPS61161 seems to use this
+                * to calibrate it's PWM sensitivity when it starts. */
+               twl4030_i2c_write_u8(TWL4030_MODULE_PWM0, MAX_VALUE,
+                                       TWL_PWM0_OFF);
+
+               /* first enable clock, then PWM0 out */
+               twl4030_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
+               r &= ~PWM0_ENABLE;
+               r |= PWM0_CLK_ENABLE;
+               twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+               r |= PWM0_ENABLE;
+               twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+
+               /* TI made it very easy to enable digital control, so easy that
+                * it often triggers unintentionally and disabes PWM control,
+                * so wait until 1 wire mode detection window ends. */
+               udelay(2000);
+       }
 
-       twl4030_i2c_write_u8(TWL4030_MODULE_PWM0, 6 + brightness,
+       twl4030_i2c_write_u8(TWL4030_MODULE_PWM0, MIN_VALUE + brightness,
                                TWL_PWM0_OFF);
 
 done:
@@ -80,6 +110,7 @@ static struct backlight_ops pwm0_backlight_ops = {
 static int pwm0_backlight_probe(struct platform_device *pdev)
 {
        struct backlight_device *bl;
+       u8 r;
 
        bl = backlight_device_register(pdev->name, &pdev->dev,
                        NULL, &pwm0_backlight_ops);
@@ -88,14 +119,18 @@ static int pwm0_backlight_probe(struct platform_device *pdev)
                return PTR_ERR(bl);
        }
 
-       twl4030_i2c_write_u8(TWL4030_MODULE_PWM0, 0x81, TWL_PWM0_ON);
+       /* 64 cycle period, ON position 0 */
+       twl4030_i2c_write_u8(TWL4030_MODULE_PWM0, 0x80, TWL_PWM0_ON);
 
-       bl->props.max_brightness = 57;
-       bl->props.brightness = 57;
+       bl->props.max_brightness = MAX_USER_VALUE;
+       bl->props.brightness = MAX_USER_VALUE;
        backlight_update_status(bl);
 
        /* enable PWM function in pin mux (i2c addr 0x49 0x92) */
-       twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, 0x04, TWL_INTBR_PMBR1);
+       twl4030_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
+       r &= ~0x0c;
+       r |= 0x04;
+       twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
 
        return 0;
 }
@@ -111,9 +146,7 @@ static int pwm0_backlight_remove(struct platform_device *pdev)
 static int pwm0_backlight_suspend(struct platform_device *pdev,
                                 pm_message_t state)
 {
-       /* turn PWM0 off */
-       twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, 0x01, TWL_INTBR_GPBR1);
-       twl4030_i2c_write_u8(TWL4030_MODULE_INTBR, 0x00, TWL_INTBR_GPBR1);
+       pwm0_disable();
        old_brightness = 0;
 
        return 0;