power: ds2781: Perform sanity check on capacity

When the factory is installing the batteries, it is inadvertently causing
some batteries to reset their fuel gauge to 0%.  Add a sanity check to
reset the capacity to a reasonable value if this condition is detected.

Change-Id: I4bc2d4e778763fd36be66ba9adb2efd371b2c7e1
Signed-off-by: Greg Meiste <w30289@motorola.com>

diff --git a/drivers/power/ds2781_battery.c b/drivers/power/ds2781_battery.c
index 155e028de3acb81a5fc64ff823726817f2c23893..5432a7085ff276aadbcb5ce0d83c249dcd658871 100644 (file)
--- a/drivers/power/ds2781_battery.c
+++ b/drivers/power/ds2781_battery.c
@@ -17,6 +17,7 @@
 
 #include <linux/android_alarm.h>
 #include <linux/debugfs.h>
+#include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/gpio.h>
 #include <linux/init.h>
@@ -62,6 +63,15 @@ struct battery_status {
 
 #define TEMP_HOT       450 /* 45.0 degrees Celcius */
 
+/* On power up, a sanity check is performed on the reported capacity. If the
+ * capacity is less than THRES_PERCENT, but the battery voltage is above
+ * THRES_BATT (when battery powered) or THRES_CHRG (when on a charger), the
+ * ACR will be reset to a reasonable value.
+ */
+#define THRES_PERCENT   5
+#define THRES_BATT      7500000
+#define THRES_CHRG      7750000
+
 #define BATTERY_LOG_MAX 1024
 #define BATTERY_LOG_MASK (BATTERY_LOG_MAX - 1)
 
@@ -202,15 +212,19 @@ static int ds2781_battery_read_status(struct ds2781_device_info *di)
        int ret;
        int start;
        int count;
+       char first_time;
+       struct battery_status *s = &di->status;
 
        /* The first time we read the entire contents of SRAM/EEPROM,
         * but after that we just read the interesting bits that change. */
        if (di->raw[DS2781_REG_RSNSP] == 0x00) {
                start = DS2781_REG_STATUS;
                count = DS2781_DATA_SIZE - start;
+               first_time = 1;
        } else {
                start = DS2781_REG_STATUS;
                count = DS2781_REG_AGE_SCALAR - start + 1;
+               first_time = 0;
        }
 
        ret = w1_ds2781_read(di->w1_dev, di->raw + start, start, count);
@@ -220,18 +234,23 @@ static int ds2781_battery_read_status(struct ds2781_device_info *di)
                return 1;
        }
 
-       mutex_lock(&di->status_lock);
-       ds2781_parse_data(di->raw, &di->status);
+       ds2781_parse_data(di->raw, s);
 
-       if (battery_log_en)
-               pr_info("batt: %3d%%, %d mV, %d mA (%d avg), %d.%d C, %d mAh\n",
-                       di->status.percentage,
-                       di->status.voltage_uV / 1000,
-                       di->status.current_uA / 1000,
-                       di->status.current_avg_uA / 1000,
-                       di->status.temp_C / 10, di->status.temp_C % 10,
-                       di->status.charge_uAh / 1000);
-       mutex_unlock(&di->status_lock);
+       if (first_time && (s->percentage < THRES_PERCENT) &&
+           (s->voltage_uV > (s->charge_source ? THRES_CHRG : THRES_BATT))) {
+               dev_err(di->dev, "Battery capacity is obviously wrong\n");
+               dev_err(di->dev, "Reset ACR registers to ~1300mAh\n");
+
+               di->raw[DS2781_REG_ACCUMULATE_CURR_MSB] = 0x08;
+               di->raw[DS2781_REG_ACCUMULATE_CURR_LSB] = 0x25;
+               w1_ds2781_write(di->w1_dev,
+                               di->raw + DS2781_REG_ACCUMULATE_CURR_MSB,
+                               DS2781_REG_ACCUMULATE_CURR_MSB, 2);
+
+               /* Give time for registers to update, then read again */
+               msleep(450);
+               return ds2781_battery_read_status(di);
+       }
 
        return 0;
 }
@@ -306,8 +325,19 @@ static void ds2781_battery_update_status(struct ds2781_device_info *di)
        u8 last_level;
        last_level = di->status.percentage;
 
+       mutex_lock(&di->status_lock);
        ds2781_battery_read_status(di);
 
+       if (battery_log_en)
+               pr_info("batt: %3d%%, %d mV, %d mA (%d avg), %d.%d C, %d mAh\n",
+                       di->status.percentage,
+                       di->status.voltage_uV / 1000,
+                       di->status.current_uA / 1000,
+                       di->status.current_avg_uA / 1000,
+                       di->status.temp_C / 10, di->status.temp_C % 10,
+                       di->status.charge_uAh / 1000);
+       mutex_unlock(&di->status_lock);
+
        if ((last_level != di->status.percentage) ||
            (di->status.temp_C >= TEMP_HOT))
                power_supply_changed(&di->bat);