add the ADC driver for the Gigabeat

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11089 a1c6a512-1295-4272-9138-f99709370657

firmware/SOURCES

@@ -301,6 +301,7 @@ target/arm/gigabeat/meg-fx/power-meg-fx.c
 target/arm/gigabeat/meg-fx/usb-meg-fx.c
 target/arm/gigabeat/meg-fx/lcd-meg-fx.c
 target/arm/gigabeat/meg-fx/sc606-meg-fx.c
+target/arm/gigabeat/meg-fx/adc-meg-fx.c
 #endif
 #endif
 

firmware/target/arm/gigabeat/meg-fx/adc-meg-fx.c

@@ -0,0 +1,78 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2006 by Wade Brown
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "cpu.h"
+#include "adc-target.h"
+
+
+void adc_init(void) {
+  /* Turn on the ADC PCLK */
+  CLKCON |= (1<<15);
+
+  /* Set channel 0, normal mode, disable "start by read" */
+  ADCCON &= ~(0x3F);
+
+  /* No start delay.  Use nromal conversion mode. */
+  ADCDLY |= 0x1;
+
+  /* Set and enable the prescaler */
+  ADCCON = (ADCCON & ~(0xff<<6)) | (0x19<<6);
+  ADCCON |= (1<<14);
+}
+
+unsigned short adc_read(int channel) {
+  int i;
+
+  /* Set the channel */
+  ADCCON = (ADCCON & ~(0x7<<3)) | (channel<<3);
+
+  /* Start the conversion process */
+  ADCCON |= 0x1;
+
+  /* Wait for a low Enable_start */
+  i = 20000;
+  while(i > 0) {
+    if(ADCCON & 0x1) {
+      i--;
+    }
+    else {
+      break;
+    }
+  }
+  if(i == 0) {
+    /* Ran out of time */
+    return(0);
+  }
+
+  /* Wait for high End_of_Conversion */
+  i = 20000;
+  while(i > 0) {
+    if(ADCCON & (1<<15)) { 	
+      break;
+    }
+    else {
+      i--;
+    }
+  }
+  if(i == 0) {
+    /* Ran out of time */
+    return(0);
+  }
+
+  return(ADCDAT0 & 0x3ff);
+}