Implement PWM backlight driver for the Meizus. Update Meizu M3 bootloader to control brightness with the touch strip.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21478 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 111 insertions, 0 deletions

diff --git a/firmware/target/arm/s5l8700/backlight-meizu.c b/firmware/target/arm/s5l8700/backlight-meizu.c
new file mode 100644
index 0000000000..43cbb16a2d
--- /dev/null
+++ b/firmware/target/arm/s5l8700/backlight-meizu.c
@@ -0,0 +1,111 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2009 by Bertrik Sikken
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include <stdbool.h>
+
+#include "config.h"
+#include "backlight.h"
+#include "backlight-target.h"
+#include "system.h"
+
+/*
+    Interrupt-driven backlight driver using the PWM mode of a hardware timer.
+    
+    Backlight brightness is implemented by configuring one of the timers in
+    the SoC for PWM mode. In this mode, two interrupts are generated for each
+    cycle, one at the start of the cycle and another one sometime between the
+    first interrupt and the start of the next cycle. The backlight is switched
+    on at the first interrupt and switched off at the second interrupt. This
+    way, the position in time of the second interrupt determines the duty cycle
+    and thereby the brightness of the backlight.
+    The backlight is switched on and off by means of a GPIO pin.
+ */
+
+void INT_TIMERA(void)
+{
+    unsigned int tacon = TACON;
+    
+    /* clear interrupts */
+    TACON = tacon;
+
+    /* TA_INT1, start of PWM cycle: enable backlight */
+    if (tacon & (1 << 17)) {
+        PDAT0 |= (1 << 2);
+    }
+    
+    /* TA_INT0, disable backlight until next cycle */
+    if (tacon & (1 << 16)) {
+        PDAT0 &= ~(1 << 2);
+    }
+}
+
+void _backlight_set_brightness(int brightness)
+{
+    if (brightness == MIN_BRIGHTNESS_SETTING) {
+        /* turn backlight fully off and disable interrupt */
+        PDAT0 &= ~(1 << 2);
+        INTMSK &= ~(1 << 5);
+    }
+    else if (brightness == MAX_BRIGHTNESS_SETTING) {
+        /* turn backlight fully on and disable interrupt */
+        PDAT0 |= (1 << 2);
+        INTMSK &= ~(1 << 5);
+    }
+    else {
+        /* set PWM width and enable interrupt */
+        TADATA0 = brightness;
+        INTMSK |= (1 << 5);
+    }
+}
+
+void _backlight_on(void)
+{
+    _backlight_set_brightness(backlight_brightness);
+}
+
+void _backlight_off(void)
+{
+    _backlight_set_brightness(MIN_BRIGHTNESS_SETTING);
+}
+
+bool _backlight_init(void)
+{
+    /* enable backlight pin as GPIO */
+    PCON0 = ((PCON0 & ~(3 << 4)) | (1 << 4));
+
+    /* enable timer clock */
+    PWRCON &= ~(1 << 4);
+
+    /* configure timer */
+    TACMD = (1 << 1);   /* TA_CLR */
+    TACMD = (1 << 0);   /* TA_EN */
+    TACON = (1 << 13) | /* TA_INT1_EN */
+            (1 << 12) | /* TA_INT0_EN */
+            (1 << 11) | /* TA_START */
+            (3 << 8) |  /* TA_CS = PCLK / 64 */
+            (1 << 4);   /* TA_MODE_SEL = PWM mode */
+    TADATA1 = MAX_BRIGHTNESS_SETTING;   /* set PWM period */
+    TAPRE = 100;    /* prescaler */
+   
+    _backlight_on();
+
+    return true;
+}
+