1 files changed, 64 insertions, 7 deletions

diff --git a/firmware/target/arm/imx31/gigabeat-s/backlight-imx31.c b/firmware/target/arm/imx31/gigabeat-s/backlight-imx31.c
index 1a41f0c53e..4df9be843c 100644
--- a/firmware/target/arm/imx31/gigabeat-s/backlight-imx31.c
+++ b/firmware/target/arm/imx31/gigabeat-s/backlight-imx31.c
@@ -17,17 +17,59 @@
  *
  ****************************************************************************/
 #include "config.h"
-#include "cpu.h"
 #include "system.h"
-#include "backlight-target.h"
 #include "backlight.h"
-#include "lcd.h"
-#include "power.h"
 #include "mc13783.h"
-#include "debug.h"
+#include "backlight-target.h"
+
+/* Table that uses combinations of current level and pwm fraction to get
+ * as many uniquely-visible brightness levels as possible. The lowest current
+ * level for any average current is used even though many combinations give
+ * duplicate values. Current (I) values are in mA. */
+static const struct
+{
+    unsigned char md;
+    unsigned char pwm;
+} led_md_pwm_table[] =
+{
+               /* I-level PWM(x/15) I-Avg */
+    { 0,  0 }, /*    0        0      0.0  */
+    { 1,  1 }, /*    3        1      0.2  */
+    { 1,  2 }, /*    3        2      0.4  */
+    { 1,  3 }, /*    3        3      0.6  */ 
+    { 1,  4 }, /*    3        4      0.8  */ 
+    { 1,  5 }, /*    3        5      1.0  */ 
+    { 1,  6 }, /*    3        6      1.2  */ 
+    { 1,  7 }, /*    3        7      1.4  */ 
+    { 1,  8 }, /*    3        8      1.6  */ 
+    { 1,  9 }, /*    3        9      1.8  */ 
+    { 1, 10 }, /*    3       10      2.0  */ 
+    { 1, 11 }, /*    3       11      2.2  */ 
+    { 1, 12 }, /*    3       12      2.4  */ /* default */
+    { 1, 13 }, /*    3       13      2.6  */ 
+    { 1, 14 }, /*    3       14      2.8  */ 
+    { 1, 15 }, /*    3       15      3.0  */ 
+    { 2,  9 }, /*    6        9      3.6  */ 
+    { 2, 10 }, /*    6       10      4.0  */ 
+    { 2, 11 }, /*    6       11      4.4  */ 
+    { 2, 12 }, /*    6       12      4.8  */ 
+    { 2, 13 }, /*    6       13      5.2  */ 
+    { 2, 14 }, /*    6       14      5.6  */ 
+    { 2, 15 }, /*    6       15      6.0  */ 
+    { 3, 11 }, /*    9       11      6.6  */ 
+    { 3, 12 }, /*    9       12      7.2  */ 
+    /* Anything higher is just too much   */
+};
 
 bool _backlight_init(void)
 {
+    mc13783_write(MC13783_LED_CONTROL0,
+                  MC13783_LEDEN |
+                  MC13783_LEDMDRAMPUP |
+                  MC13783_LEDMDRAMPDOWN |
+                  MC13783_BOOSTEN |
+                  MC13783_ABMODE_MONCH_LEDMD1234 |
+                  MC13783_ABREF_400MV);
     return true;
 }
 
@@ -46,6 +88,21 @@ void _backlight_off(void)
 /* Assumes that the backlight has been initialized */
 void _backlight_set_brightness(int brightness)
 {
-    (void)brightness;
-}
+    uint32_t data, md, pwm;
 
+    if ((unsigned)brightness >= ARRAYLEN(led_md_pwm_table))
+        brightness = DEFAULT_BRIGHTNESS_SETTING;
+
+    data = mc13783_read(MC13783_LED_CONTROL2);
+
+    if (data == (uint32_t)-1)
+        return;
+
+    md = led_md_pwm_table[brightness].md;
+    pwm = led_md_pwm_table[brightness].pwm;
+
+    data &= ~(MC13783_LEDMD | MC13783_LEDMDDC);
+    data |= MC13783_LEDMDw(md) | MC13783_LEDMDDCw(pwm);
+
+    mc13783_write(MC13783_LED_CONTROL2, data);
+}