From b12c69bac7a02ea161ebc02ce7323e82bebe7b23 Mon Sep 17 00:00:00 2001
From: Michael Sevakis <jethead71@rockbox.org>
Date: Sun, 13 Apr 2008 20:03:08 +0000
Subject: ADC driver for Gigabeat S - a bit on the general side for now. Needs
 to have scales set properly (what physical value a reading represents isn't
 clear from the docs or I'm just lazy atm). Throw-in a _bunch_ more reg
 defines for the PMIC. Show all 16 raw channels values in debug menu.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17100 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/target/arm/imx31/gigabeat-s/adc-imx31.c | 103 ++++++++++++++++++-----
 1 file changed, 81 insertions(+), 22 deletions(-)

(limited to 'firmware/target/arm/imx31/gigabeat-s/adc-imx31.c')

diff --git a/firmware/target/arm/imx31/gigabeat-s/adc-imx31.c b/firmware/target/arm/imx31/gigabeat-s/adc-imx31.c
index 1fd2247ef1..b1b79a7989 100644
--- a/firmware/target/arm/imx31/gigabeat-s/adc-imx31.c
+++ b/firmware/target/arm/imx31/gigabeat-s/adc-imx31.c
@@ -7,7 +7,7 @@
  *                     \/            \/     \/    \/            \/
  * $Id$
  *
- * Copyright (C) 2006 by Wade Brown
+ * Copyright (C) 2008 by Michael Sevakis
  *
  * 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.
@@ -16,37 +16,96 @@
  * KIND, either express or implied.
  *
  ****************************************************************************/
-#include "cpu.h"
+#include "config.h"
+#include "system.h"
+#include "mc13783.h"
 #include "adc-target.h"
 #include "kernel.h"
 
-/* prototypes */
-static unsigned short __adc_read(int channel);
-static void adc_tick(void);
-
-void adc_init(void) 
+/* Do this so we may read all channels in a single SPI message */
+static const unsigned char reg_array[NUM_ADC_CHANNELS/2] =
 {
-}
+    MC13783_ADC2,
+    MC13783_ADC2,
+    MC13783_ADC2,
+    MC13783_ADC2,
+    MC13783_ADC2,
+    MC13783_ADC2,
+    MC13783_ADC2,
+    MC13783_ADC2,
+};
 
-/* Called to get the recent ADC reading */
-inline unsigned short adc_read(int channel)
+static uint32_t channels[2][NUM_ADC_CHANNELS/2];
+static struct wakeup adc_wake;
+static struct mutex adc_mtx;
+static long last_adc_read[2]; /* One for each input group */
+
+/* Read 10-bit ADC channel */
+unsigned short adc_read(int channel)
 {
-    (void)channel;
-    return 0;
+    uint32_t data;
+    int input_select;
+
+    if ((unsigned)channel >= NUM_ADC_CHANNELS)
+        return ADC_READ_ERROR;
+
+    mutex_lock(&adc_mtx);
+
+    input_select = channel >> 3;
+
+    /* Limit the traffic through here */
+    if (TIME_AFTER(current_tick, last_adc_read[input_select]))
+    {
+        /* Keep enable, start conversion, increment from channel 0,
+         * increment from channel 4 */
+        uint32_t adc1 = MC13783_ADEN | MC13783_ASC | MC13783_ADA1w(0) |
+                        MC13783_ADA2w(4);
+
+        if (input_select == 1)
+            adc1 |= MC13783_ADSEL; /* 2nd set of inputs */
+
+        /* Start conversion */
+        mc13783_write(MC13783_ADC1, adc1);
+
+        /* Wait for done signal */
+        wakeup_wait(&adc_wake, TIMEOUT_BLOCK);
+
+        /* Read all 8 channels that are converted - two channels in each
+         * word. */
+        mc13783_read_regset(reg_array, channels[input_select],
+                            NUM_ADC_CHANNELS/2);
+
+        last_adc_read[input_select] = current_tick;
+    }
+
+    data = channels[input_select][channel & 7];
+
+    mutex_unlock(&adc_mtx);
+
+    /* Extract the bitfield depending on even or odd channel number */
+    return (channel & 1) ? MC13783_ADD2r(data) : MC13783_ADD1r(data);
 }
 
-/** 
-  * Read the ADC by polling
-  * @param channel The ADC channel to read
-  * @return 10bit reading from ADC channel or ADC_READ_ERROR if timeout
-  */
-static unsigned short __adc_read(int channel) 
+/* Called when conversion is complete */
+void adc_done(void)
 {
-    (void)channel;
-    return 0;
+    wakeup_signal(&adc_wake);
 }
 
-/* add this to the tick so that the ADC converts are done in the background */
-static void adc_tick(void)
+void adc_init(void) 
 {
+    wakeup_init(&adc_wake);
+    mutex_init(&adc_mtx);
+
+    /* Init so first reads get data */
+    last_adc_read[0] = last_adc_read[1] = current_tick-1;
+
+    /* Enable increment-by-read, thermistor */
+    mc13783_write(MC13783_ADC0, MC13783_ADINC2 | MC13783_ADINC1 |
+                  MC13783_RTHEN);
+    /* Enable ADC, set multi-channel mode */
+    mc13783_write(MC13783_ADC1, MC13783_ADEN);
+    /* Enable the ADCDONE interrupt - notifications are dispatched by
+     * event handler. */
+    mc13783_clear(MC13783_INTERRUPT_MASK0, MC13783_ADCDONE);
 }
-- 
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