From adbd2969e6e6fd584d46ef60a3fa40bf878d7e00 Mon Sep 17 00:00:00 2001
From: Cástor Muñoz <cmvidal@gmail.com>
Date: Fri, 12 Aug 2016 02:37:45 +0200
Subject: iPod Classic: ADC updates

Add code to read USB D+/D- and accessory ADCs, it is shown in HW
debug menu, might be useful in future for RB and/or the bootloader
to identify external USB chargers.

Change-Id: Ia48ca5e06bb7ddc52bb55abedde6734653ce8dba
---
 firmware/target/arm/s5l8702/ipod6g/adc-ipod6g.c | 84 ++++++++++++++++++++++++-
 1 file changed, 81 insertions(+), 3 deletions(-)

(limited to 'firmware/target/arm/s5l8702/ipod6g/adc-ipod6g.c')

diff --git a/firmware/target/arm/s5l8702/ipod6g/adc-ipod6g.c b/firmware/target/arm/s5l8702/ipod6g/adc-ipod6g.c
index 201af5ee00..fbe5ef805e 100644
--- a/firmware/target/arm/s5l8702/ipod6g/adc-ipod6g.c
+++ b/firmware/target/arm/s5l8702/ipod6g/adc-ipod6g.c
@@ -18,7 +18,7 @@
  * KIND, either express or implied.
  *
  ****************************************************************************/
- 
+
 #include "config.h"
 
 #include "inttypes.h"
@@ -28,12 +28,90 @@
 #include "pmu-target.h"
 #include "kernel.h"
 
+
+/* MS_TO_TICKS converts a milisecond time period into the
+ * corresponding amount of ticks. If the time period cannot
+ * be accurately measured in ticks it will round up.
+ */
+#define MS_PER_HZ (1000/HZ)
+#define MS_TO_TICKS(x) (((x)+MS_PER_HZ-1)/MS_PER_HZ)
+
+static const struct pmu_adc_channel adc_channels[] =
+{
+    [ADC_BATTERY] =
+    {
+        .name = "Battery",
+        .adcc1 = PCF5063X_ADCC1_MUX_BATSNS_SUBTR
+               | PCF5063X_ADCC1_AVERAGE_4
+               | PCF5063X_ADCC1_RES_10BIT,
+    },
+
+    [ADC_USBDATA] =
+    {
+        .name = "USB D+/D-",
+        .adcc1 = PCF5063X_ADCC1_MUX_ADCIN2_RES
+               | PCF5063X_ADCC1_AVERAGE_16
+               | PCF5063X_ADCC1_RES_10BIT,
+        .adcc3 = PCF5063X_ADCC3_RES_DIV_THREE,
+    },
+
+    [ADC_ACCESSORY] =
+    {
+        .name = "Accessory",
+        .adcc1 = PCF5063X_ADCC1_MUX_ADCIN1
+               | PCF5063X_ADCC1_AVERAGE_16
+               | PCF5063X_ADCC1_RES_10BIT,
+        .adcc2 = PCF5063X_ADCC2_RATIO_ADCIN1
+               | PCF5063X_ADCC2_RATIOSETTL_10US,
+        .adcc3 = PCF5063X_ADCC3_ACCSW_EN,
+        .bias_dly = MS_TO_TICKS(50),
+    },
+};
+
+const char *adc_name(int channel)
+{
+    return adc_channels[channel].name;
+}
+
+unsigned short adc_read_millivolts(int channel)
+{
+    const struct pmu_adc_channel *ch = &adc_channels[channel];
+    return pmu_adc_raw2mv(ch, pmu_read_adc(ch));
+}
+
+/* Returns battery voltage [millivolts] */
+unsigned int adc_read_battery_voltage(void)
+{
+    return adc_read_millivolts(ADC_BATTERY);
+}
+
+/* Returns USB D+/D- voltage from ADC [millivolts] */
+unsigned int adc_read_usbdata_voltage(bool dp)
+{
+    unsigned int mvolts;
+    int gpio = dp ? 0xb0300 : 0xb0200; /* select D+/D- */
+    GPIOCMD = gpio | 0xf; /* route to ADCIN2 */
+    mvolts = adc_read_millivolts(ADC_USBDATA);
+    GPIOCMD = gpio | 0xe; /* unroute */
+    return mvolts;
+}
+
+/* Returns resistor connected to "Accessory identify" pin [ohms] */
+#define IAP_DEVICE_RESISTOR 100000  /* ohms */
+int adc_read_accessory_resistor(void)
+{
+    int raw = pmu_read_adc(&adc_channels[ADC_ACCESSORY]);
+    return (1023-raw) ? raw * IAP_DEVICE_RESISTOR / (1023-raw)
+                      : -1 /* open circuit */;
+}
+
+
+/* API functions */
 unsigned short adc_read(int channel)
 {
-    return pmu_read_adc(channel);
+    return pmu_read_adc(&adc_channels[channel]);
 }
 
 void adc_init(void)
 {
 }
-
-- 
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