iio: dht11: Add locking

Make sure that the read function is not interrupted...

Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Harald Geyer <harald@ccbib.org>
Reviewed-by: Sanjeev Sharma <sanjeev_sharma@mentor.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
index f546ecae90f15295808f80ab3a18c7830780b533..7717f5c3395bc9288f0bfd9abf739b17365d0491 100644 (file)
--- a/drivers/iio/humidity/dht11.c
+++ b/drivers/iio/humidity/dht11.c
@@ -29,6 +29,7 @@
 #include <linux/wait.h>
 #include <linux/bitops.h>
 #include <linux/completion.h>
+#include <linux/mutex.h>
 #include <linux/delay.h>
 #include <linux/gpio.h>
 #include <linux/of_gpio.h>
@@ -57,6 +58,7 @@ struct dht11 {
        int                             irq;
 
        struct completion               completion;
+       struct mutex                    lock;
 
        s64                             timestamp;
        int                             temperature;
@@ -145,6 +147,7 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
        struct dht11 *dht11 = iio_priv(iio_dev);
        int ret;
 
+       mutex_lock(&dht11->lock);
        if (dht11->timestamp + DHT11_DATA_VALID_TIME < iio_get_time_ns()) {
                reinit_completion(&dht11->completion);
 
@@ -185,6 +188,7 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
                ret = -EINVAL;
 err:
        dht11->num_edges = -1;
+       mutex_unlock(&dht11->lock);
        return ret;
 }
 
@@ -268,6 +272,7 @@ static int dht11_probe(struct platform_device *pdev)
        platform_set_drvdata(pdev, iio);
 
        init_completion(&dht11->completion);
+       mutex_init(&dht11->lock);
        iio->name = pdev->name;
        iio->dev.parent = &pdev->dev;
        iio->info = &dht11_iio_info;