jz4740-battery: Protect against concurrent battery readings

We can not handle more then one ADC request at a time to the battery.
The patch adds a mutex around the ADC read code to ensure this.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: stable@kernel.org
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

diff --git a/drivers/power/jz4740-battery.c b/drivers/power/jz4740-battery.c
index a8108a7..2bbe04a 100644 (file)
--- a/drivers/power/jz4740-battery.c
+++ b/drivers/power/jz4740-battery.c
@@ -47,6 +47,8 @@ struct jz_battery {
 
        struct power_supply battery;
        struct delayed_work work;
+
+       struct mutex lock;
 };
 
 static inline struct jz_battery *psy_to_jz_battery(struct power_supply *psy)
@@ -68,6 +70,8 @@ static long jz_battery_read_voltage(struct jz_battery *battery)
        unsigned long val;
        long voltage;
 
+       mutex_lock(&battery->lock);
+
        INIT_COMPLETION(battery->read_completion);
 
        enable_irq(battery->irq);
@@ -91,6 +95,8 @@ static long jz_battery_read_voltage(struct jz_battery *battery)
        battery->cell->disable(battery->pdev);
        disable_irq(battery->irq);
 
+       mutex_unlock(&battery->lock);
+
        return voltage;
 }
 
@@ -291,6 +297,7 @@ static int __devinit jz_battery_probe(struct platform_device *pdev)
        jz_battery->pdev = pdev;
 
        init_completion(&jz_battery->read_completion);
+       mutex_init(&jz_battery->lock);
 
        INIT_DELAYED_WORK(&jz_battery->work, jz_battery_work);