From 57dcfe0eee31364771d71fe32395058de3af3fa6 Mon Sep 17 00:00:00 2001
From: Jens Arnold <amiconn@rockbox.org>
Date: Sat, 5 Jun 2010 11:48:12 +0000
Subject: Implement backlight brightness for iPod G4 greyscale and iPod
 Color/Photo.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26573 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/target/arm/ipod/backlight-4g_color.c | 39 ++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 10 deletions(-)

(limited to 'firmware/target/arm/ipod/backlight-4g_color.c')

diff --git a/firmware/target/arm/ipod/backlight-4g_color.c b/firmware/target/arm/ipod/backlight-4g_color.c
index 656bef0e17..a0e14c99e3 100644
--- a/firmware/target/arm/ipod/backlight-4g_color.c
+++ b/firmware/target/arm/ipod/backlight-4g_color.c
@@ -34,28 +34,47 @@
 #include "backlight.h"
 #include "backlight-target.h"
 
+/* Index 0 is a dummy, 1..31 are used */
+static unsigned char log_brightness[32] = {
+      0,   1,   2,   4,   6,   9,  12,  16,  20,  25,  30,  36,
+     42,  49,  56,  64,  72,  81,  90, 100, 110, 121, 132, 144,
+    156, 169, 182, 196, 210, 225, 240, 255
+};
+
+static unsigned brightness = 100;   /* 1 to 255 */
+static bool enabled = false;
+
+/* Handling B03 in _backlight_on() and _backlight_off() makes backlight go off
+ * without delay. Not doing that does a short (fixed) fade out. Opt for the
+ * latter. */
+
 void _backlight_on(void)
 {
     /* brightness full */
-    outl(0x80000000 | (0xff << 16), 0x7000a010);
-
-    /* set port b bit 3 on */
-    GPIO_SET_BITWISE(GPIOB_OUTPUT_VAL, 0x08);
+    outl(0x80000000 | (brightness << 16), 0x7000a010);
+    /* GPIO_SET_BITWISE(GPIOB_OUTPUT_VAL, 0x08); */
+    enabled = true;
 }
 
 void _backlight_off(void)
 {
-    /* fades backlight off on 4g */
-    GPO32_ENABLE &= ~0x2000000;
     outl(0x80000000, 0x7000a010);
+    /* GPIO_CLEAR_BITWISE(GPIOB_OUTPUT_VAL, 0x08); */
+    enabled = false;
+}
+
+void _backlight_set_brightness(int val)
+{
+    brightness = log_brightness[val];
+    if (enabled)
+        outl(0x80000000 | (brightness << 16), 0x7000a010);
 }
 
 bool _backlight_init(void)
 {
-    GPIOB_ENABLE |= 0x4; /* B02 enable */
-    GPIOB_ENABLE |= 0x8; /* B03 enable */
-    GPO32_ENABLE |= 0x2000000; /* D01 enable */
-    GPO32_VAL |= 0x2000000;  /* D01 =1 */
+    GPIO_SET_BITWISE(GPIOB_ENABLE, 0x0c); /* B02 and B03 enable */
+    GPIO_SET_BITWISE(GPIOB_OUTPUT_VAL, 0x08); /* B03 = 1 */
+    GPO32_ENABLE &= ~0x2000000; /* D01 disable, so pwm takes over */
     DEV_EN |= DEV_PWM;   /* PWM enable */
 
     _backlight_on();
-- 
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