bq20z75: Add support for external notification

Adding support for external power change notification. One problem found
is that there is a lag time before the sensor will return a new status.
To ensure that we only fire off the power_supply_changed event when the
status returned from the sensor is actually different, we delay sending
the the notification, and instead poll on it looking for a change. The
amount of time to poll is configurable via platform data.

Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

diff --git a/drivers/power/bq20z75.c b/drivers/power/bq20z75.c
index 506585e..e1adc0e 100644 (file)
--- a/drivers/power/bq20z75.c
+++ b/drivers/power/bq20z75.c
@@ -152,6 +152,10 @@ struct bq20z75_info {
        bool                            gpio_detect;
        bool                            enable_detection;
        int                             irq;
+       int                             last_state;
+       int                             poll_time;
+       struct delayed_work             work;
+       int                             ignore_changes;
 };
 
 static int bq20z75_read_word_data(struct i2c_client *client, u8 address)
@@ -279,6 +283,7 @@ static int bq20z75_get_battery_property(struct i2c_client *client,
        int reg_offset, enum power_supply_property psp,
        union power_supply_propval *val)
 {
+       struct bq20z75_info *bq20z75_device = i2c_get_clientdata(client);
        s32 ret;
 
        ret = bq20z75_read_word_data(client,
@@ -293,15 +298,24 @@ static int bq20z75_get_battery_property(struct i2c_client *client,
        if (ret >= bq20z75_data[reg_offset].min_value &&
            ret <= bq20z75_data[reg_offset].max_value) {
                val->intval = ret;
-               if (psp == POWER_SUPPLY_PROP_STATUS) {
-                       if (ret & BATTERY_FULL_CHARGED)
-                               val->intval = POWER_SUPPLY_STATUS_FULL;
-                       else if (ret & BATTERY_FULL_DISCHARGED)
-                               val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
-                       else if (ret & BATTERY_DISCHARGING)
-                               val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
-                       else
-                               val->intval = POWER_SUPPLY_STATUS_CHARGING;
+               if (psp != POWER_SUPPLY_PROP_STATUS)
+                       return 0;
+
+               if (ret & BATTERY_FULL_CHARGED)
+                       val->intval = POWER_SUPPLY_STATUS_FULL;
+               else if (ret & BATTERY_FULL_DISCHARGED)
+                       val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
+               else if (ret & BATTERY_DISCHARGING)
+                       val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
+               else
+                       val->intval = POWER_SUPPLY_STATUS_CHARGING;
+
+               if (bq20z75_device->poll_time == 0)
+                       bq20z75_device->last_state = val->intval;
+               else if (bq20z75_device->last_state != val->intval) {
+                       cancel_delayed_work_sync(&bq20z75_device->work);
+                       power_supply_changed(&bq20z75_device->power_supply);
+                       bq20z75_device->poll_time = 0;
                }
        } else {
                if (psp == POWER_SUPPLY_PROP_STATUS)
@@ -545,6 +559,60 @@ static irqreturn_t bq20z75_irq(int irq, void *devid)
        return IRQ_HANDLED;
 }
 
+static void bq20z75_external_power_changed(struct power_supply *psy)
+{
+       struct bq20z75_info *bq20z75_device;
+
+       bq20z75_device = container_of(psy, struct bq20z75_info, power_supply);
+
+       if (bq20z75_device->ignore_changes > 0) {
+               bq20z75_device->ignore_changes--;
+               return;
+       }
+
+       /* cancel outstanding work */
+       cancel_delayed_work_sync(&bq20z75_device->work);
+
+       schedule_delayed_work(&bq20z75_device->work, HZ);
+       bq20z75_device->poll_time = bq20z75_device->pdata->poll_retry_count;
+}
+
+static void bq20z75_delayed_work(struct work_struct *work)
+{
+       struct bq20z75_info *bq20z75_device;
+       s32 ret;
+
+       bq20z75_device = container_of(work, struct bq20z75_info, work.work);
+
+       ret = bq20z75_read_word_data(bq20z75_device->client,
+                                    bq20z75_data[REG_STATUS].addr);
+       /* if the read failed, give up on this work */
+       if (ret < 0) {
+               bq20z75_device->poll_time = 0;
+               return;
+       }
+
+       if (ret & BATTERY_FULL_CHARGED)
+               ret = POWER_SUPPLY_STATUS_FULL;
+       else if (ret & BATTERY_FULL_DISCHARGED)
+               ret = POWER_SUPPLY_STATUS_NOT_CHARGING;
+       else if (ret & BATTERY_DISCHARGING)
+               ret = POWER_SUPPLY_STATUS_DISCHARGING;
+       else
+               ret = POWER_SUPPLY_STATUS_CHARGING;
+
+       if (bq20z75_device->last_state != ret) {
+               bq20z75_device->poll_time = 0;
+               power_supply_changed(&bq20z75_device->power_supply);
+               return;
+       }
+       if (bq20z75_device->poll_time > 0) {
+               schedule_delayed_work(&bq20z75_device->work, HZ);
+               bq20z75_device->poll_time--;
+               return;
+       }
+}
+
 static int __devinit bq20z75_probe(struct i2c_client *client,
        const struct i2c_device_id *id)
 {
@@ -566,6 +634,13 @@ static int __devinit bq20z75_probe(struct i2c_client *client,
        bq20z75_device->power_supply.num_properties =
                ARRAY_SIZE(bq20z75_properties);
        bq20z75_device->power_supply.get_property = bq20z75_get_property;
+       /* ignore first notification of external change, it is generated
+        * from the power_supply_register call back
+        */
+       bq20z75_device->ignore_changes = 1;
+       bq20z75_device->last_state = POWER_SUPPLY_STATUS_UNKNOWN;
+       bq20z75_device->power_supply.external_power_changed =
+               bq20z75_external_power_changed;
 
        if (pdata) {
                bq20z75_device->gpio_detect =
@@ -625,6 +700,8 @@ skip_gpio:
        dev_info(&client->dev,
                "%s: battery gas gauge device registered\n", client->name);
 
+       INIT_DELAYED_WORK(&bq20z75_device->work, bq20z75_delayed_work);
+
        return 0;
 
 exit_psupply:
@@ -648,6 +725,9 @@ static int __devexit bq20z75_remove(struct i2c_client *client)
                gpio_free(bq20z75_device->pdata->battery_detect);
 
        power_supply_unregister(&bq20z75_device->power_supply);
+
+       cancel_delayed_work_sync(&bq20z75_device->work);
+
        kfree(bq20z75_device);
        bq20z75_device = NULL;
 
@@ -661,6 +741,9 @@ static int bq20z75_suspend(struct i2c_client *client,
        struct bq20z75_info *bq20z75_device = i2c_get_clientdata(client);
        s32 ret;
 
+       if (bq20z75_device->poll_time > 0)
+               cancel_delayed_work_sync(&bq20z75_device->work);
+
        /* write to manufacturer access with sleep command */
        ret = bq20z75_write_word_data(client,
                bq20z75_data[REG_MANUFACTURER_DATA].addr,

diff --git a/include/linux/power/bq20z75.h b/include/linux/power/bq20z75.h
index b0843b6..1398eb0 100644 (file)
--- a/include/linux/power/bq20z75.h
+++ b/include/linux/power/bq20z75.h
@@ -29,11 +29,14 @@
  * @battery_detect:            GPIO which is used to detect battery presence
  * @battery_detect_present:    gpio state when battery is present (0 / 1)
  * @i2c_retry_count:           # of times to retry on i2c IO failure
+ * @poll_retry_count:          # of times to retry looking for new status after
+ *                             external change notification
  */
 struct bq20z75_platform_data {
        int battery_detect;
        int battery_detect_present;
        int i2c_retry_count;
+       int poll_retry_count;
 };
 
 #endif