pm2301-charger: Wake device on register access

When USB  Dedicated or Standard host chargers are plugged into
the device, chargealg attempts to disable the PM2301 AC charger,
However, disabling PM2301 was failing because of it being in
runtime suepend mode & LPN pin being low.

Signed-off-by: Rupesh Kumar <rupesh.kumar@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Marcus COOPER <marcus.xm.cooper@stericsson.com>
Reviewed-by: Philippe LANGLAIS <philippe.langlais@stericsson.com>

drivers/power/pm2301_charger.c

@@ -128,43 +128,33 @@ static void clear_lpn_pin(struct pm2xxx_charger *pm2)
 static int pm2xxx_reg_read(struct pm2xxx_charger *pm2, int reg, u8 *val)
 {
 	int ret;
-	/*
-	 * When AC adaptor is unplugged, the host
-	 * must put LPN high to be able to
-	 * communicate by I2C with PM2301
-	 * and receive I2C "acknowledge" from PM2301.
-	 */
-	mutex_lock(&pm2->lock);
+
+	/* wake up the device */
+	pm_runtime_get_sync(pm2->dev);
 
 	ret = i2c_smbus_read_i2c_block_data(pm2->config.pm2xxx_i2c, reg,
 				1, val);
 	if (ret < 0)
 		dev_err(pm2->dev, "Error reading register at 0x%x\n", reg);
 	else
 		ret = 0;
-	mutex_unlock(&pm2->lock);
 
 	return ret;
 }
 
 static int pm2xxx_reg_write(struct pm2xxx_charger *pm2, int reg, u8 val)
 {
 	int ret;
-	/*
-	 * When AC adaptor is unplugged, the host
-	 * must put LPN high to be able to
-	 * communicate by I2C with PM2301
-	 * and receive I2C "acknowledge" from PM2301.
-	 */
-	mutex_lock(&pm2->lock);
+
+	/* wake up the device */
+	pm_runtime_get_sync(pm2->dev);
 
 	ret = i2c_smbus_write_i2c_block_data(pm2->config.pm2xxx_i2c, reg,
 				1, &val);
 	if (ret < 0)
 		dev_err(pm2->dev, "Error writing register at 0x%x\n", reg);
 	else
 		ret = 0;
-	mutex_unlock(&pm2->lock);
 
 	return ret;
 }