Sansa Connect: Read HDQ battery data

Make it possible for target to provide voltage, percentage and time to
empty values. The voltage measurement is nice to have in debug menu even
if the actions are taken only based on percentage. Perform battery level
estimation based on voltage only if percentage is not available.

Use time to empty based on actual power consumption. This makes the
estimated runtime displayed in Rockbox Info to react to backlight
setting. The bq27000 updates time to empty estimate every 5.12 seconds
so it is possible to see the estimate with backlight off on the screen
if user enters Rockbox Info, activates hold switch, waits 11 seconds and
releases the hold switch.

Change-Id: Iafe3fa0fb334e3428e3a0ad05b2c020d208dc934

3 files changed, 137 insertions, 1 deletions

diff --git a/firmware/target/arm/tms320dm320/sansa-connect/avr-sansaconnect.c b/firmware/target/arm/tms320dm320/sansa-connect/avr-sansaconnect.c
index 8ebba3a8d5..ed7dab1572 100644
--- a/firmware/target/arm/tms320dm320/sansa-connect/avr-sansaconnect.c
+++ b/firmware/target/arm/tms320dm320/sansa-connect/avr-sansaconnect.c
@@ -104,8 +104,15 @@
 #define SYS_CTRL_EN_TS_THERM    0x06
 #define SYS_CTRL_FRESET         0x80
 
+/* HDQ status codes */
+#define HDQ_STATUS_OK           0x00
+#define HDQ_STATUS_NOT_READY    0x01
+#define HDQ_STATUS_TIMEOUT      0x02
+
 /* protects spi avr commands from concurrent access */
 static struct mutex avr_mtx;
+/* serializes hdq read/write and status retrieval */
+static struct mutex hdq_mtx;
 
 /* AVR thread events */
 #define INPUT_INTERRUPT          1
@@ -498,6 +505,7 @@ void avr_hid_init(void)
     IO_SERIAL1_MODE = 0x6DB;
 
     mutex_init(&avr_mtx);
+    mutex_init(&hdq_mtx);
 }
 
 int _battery_level(void)
@@ -510,6 +518,17 @@ int _battery_level(void)
     return avr_battery_level & BATTERY_LEVEL_PERCENTAGE_MASK;
 }
 
+int _battery_voltage(void)
+{
+    return avr_hid_hdq_read_short(HDQ_REG_VOLT);
+}
+
+int _battery_time(void)
+{
+    /* HDQ_REG_TTE reads as 65535 when charging */
+    return avr_hid_hdq_read_short(HDQ_REG_TTE);
+}
+
 unsigned int power_input_status(void)
 {
     if (avr_battery_status & BATTERY_STATUS_CHARGER_CONNECTED)
@@ -524,6 +543,70 @@ bool charging_state(void)
     return (avr_battery_status & BATTERY_STATUS_CHARGING) != 0;
 }
 
+static int avr_hid_hdq_read_byte_internal(uint8_t address)
+{
+    uint8_t result[2];
+
+    if (!avr_execute_command(CMD_HDQ_READ, &address, sizeof(address)))
+    {
+        return -1;
+    }
+
+    do
+    {
+        mdelay(10);
+        if (!avr_execute_command(CMD_HDQ_STATUS, result, sizeof(result)))
+        {
+            return -1;
+        }
+    }
+    while (result[0] == HDQ_STATUS_NOT_READY);
+
+    if (result[0] != HDQ_STATUS_OK)
+    {
+        logf("HDQ read %d status %d", address, result[0]);
+        return -1;
+    }
+
+    return result[1];
+}
+
+int avr_hid_hdq_read_byte(uint8_t address)
+{
+    int retry;
+    int value = -1;
+    for (retry = 0; (retry < 3) && (value < 0); retry++)
+    {
+        mutex_lock(&hdq_mtx);
+        value = avr_hid_hdq_read_byte_internal(address);
+        mutex_unlock(&hdq_mtx);
+    }
+    return value;
+}
+
+int avr_hid_hdq_read_short(uint8_t address)
+{
+    int old_hi = -1, old_lo = -1, hi = -2, lo = -2;
+    /* Keep reading until we read the same value twice.
+     * There's no atomic 16-bit value retrieval, so keep reading
+     * until we read the same value twice. HDQ registers update
+     * no more than once per 2.56 seconds so usually there will
+     * be 4 reads and sometimes 6 reads.
+     */
+    while ((old_hi != hi) || (old_lo != lo))
+    {
+        old_hi = hi;
+        old_lo = lo;
+        hi = avr_hid_hdq_read_byte(address + 1);
+        lo = avr_hid_hdq_read_byte(address);
+    }
+    if ((hi < 0) || (lo < 0))
+    {
+        return -1;
+    }
+    return (hi << 8) | lo;
+}
+
 static void avr_hid_enable_wheel(void)
 {
     uint8_t enable = 0x01;
diff --git a/firmware/target/arm/tms320dm320/sansa-connect/avr-sansaconnect.h b/firmware/target/arm/tms320dm320/sansa-connect/avr-sansaconnect.h
index baa7083760..ed23e84936 100644
--- a/firmware/target/arm/tms320dm320/sansa-connect/avr-sansaconnect.h
+++ b/firmware/target/arm/tms320dm320/sansa-connect/avr-sansaconnect.h
@@ -24,8 +24,38 @@
 
 #include "config.h"
 
+/* HDQ (bq27000) RAM registers */
+#define HDQ_REG_CTRL            0x00
+#define HDQ_REG_MODE            0x01
+#define HDQ_REG_AR              0x02
+#define HDQ_REG_ARTTE           0x04
+#define HDQ_REG_TEMP            0x06
+#define HDQ_REG_VOLT            0x08
+#define HDQ_REG_FLAGS           0x0A
+#define HDQ_REG_RSOC            0x0B
+#define HDQ_REG_NAC             0x0C
+#define HDQ_REG_CACD            0x0E
+#define HDQ_REG_CACT            0x10
+#define HDQ_REG_LMD             0x12
+#define HDQ_REG_AI              0x14
+#define HDQ_REG_TTE             0x16
+#define HDQ_REG_TTF             0x18
+#define HDQ_REG_SI              0x1A
+#define HDQ_REG_STTE            0x1C
+#define HDQ_REG_MLI             0x1E
+#define HDQ_REG_MLTTE           0x20
+#define HDQ_REG_SAE             0x22
+#define HDQ_REG_AP              0x24
+#define HDQ_REG_TTECP           0x26
+#define HDQ_REG_CYCL            0x28
+#define HDQ_REG_CYCT            0x2A
+#define HDQ_REG_CSOC            0x2C
+
 void avr_hid_init(void);
 
+int avr_hid_hdq_read_byte(uint8_t address);
+int avr_hid_hdq_read_short(uint8_t address);
+
 void avr_hid_enable_charger(void);
 
 void avr_hid_wifi_pd(int high);
diff --git a/firmware/target/arm/tms320dm320/sansa-connect/power-sansaconnect.c b/firmware/target/arm/tms320dm320/sansa-connect/power-sansaconnect.c
index ccd91c6d2f..597fb6b7e0 100644
--- a/firmware/target/arm/tms320dm320/sansa-connect/power-sansaconnect.c
+++ b/firmware/target/arm/tms320dm320/sansa-connect/power-sansaconnect.c
@@ -31,6 +31,29 @@
 #include "i2c-dm320.h"
 #include "logf.h"
 
+
+const unsigned short battery_level_dangerous[BATTERY_TYPES_COUNT] =
+{
+    3450
+};
+
+const unsigned short battery_level_shutoff[BATTERY_TYPES_COUNT] =
+{
+    3400
+};
+
+/* voltages (millivolt) of 0%, 10%, ... 100% when charging disabled */
+const unsigned short percent_to_volt_discharge[BATTERY_TYPES_COUNT][11] =
+{
+    { 3400, 3508, 3630, 3703, 3727, 3750, 3803, 3870, 3941, 4026, 4142 }
+};
+
+/* voltages (millivolt) of 0%, 10%, ... 100% when charging enabled */
+const unsigned short percent_to_volt_charge[11] =
+{
+    3540, 3788, 3860, 3890, 3916, 3956, 4016, 4085, 4164, 4180, 4190
+};
+
 /* (7-bit) address is 0x48, the LSB is read/write flag */
 #define TPS65021_ADDR (0x48 << 1)
 
@@ -54,7 +77,7 @@ void power_init(void)
 
     /* PWM mode */
     tps65021_write_reg(0x04, 0xB2);
- 
+
     /* Set core voltage to 1.5V */
     tps65021_write_reg(0x06, 0x1C);