iio: adc: ti-adc128s052: Simplify using guard(mutex)

Error path in ADC reading function can be slighly simplified using the
guard(mutex).

Use guard(mutex) and document the mutex purpose.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://patch.msgid.link/c4262cbf55748d505a74249d2bf46d7c3594d838.1744022065.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
index d90a5ca..fa00993 100644 (file)
--- a/drivers/iio/adc/ti-adc128s052.c
+++ b/drivers/iio/adc/ti-adc128s052.c
@@ -9,6 +9,7 @@
  * https://www.ti.com/lit/ds/symlink/adc124s021.pdf
  */
 
+#include <linux/cleanup.h>
 #include <linux/err.h>
 #include <linux/iio/iio.h>
 #include <linux/mod_devicetable.h>
@@ -26,6 +27,10 @@ struct adc128 {
        struct spi_device *spi;
 
        struct regulator *reg;
+       /*
+        * Serialize the SPI 'write-channel + read data' accesses and protect
+        * the shared buffer.
+        */
        struct mutex lock;
 
        union {
@@ -38,19 +43,16 @@ static int adc128_adc_conversion(struct adc128 *adc, u8 channel)
 {
        int ret;
 
-       mutex_lock(&adc->lock);
+       guard(mutex)(&adc->lock);
 
        adc->buffer[0] = channel << 3;
        adc->buffer[1] = 0;
 
        ret = spi_write(adc->spi, &adc->buffer, sizeof(adc->buffer));
-       if (ret < 0) {
-               mutex_unlock(&adc->lock);
+       if (ret < 0)
                return ret;
-       }
 
        ret = spi_read(adc->spi, &adc->buffer16, sizeof(adc->buffer16));
-       mutex_unlock(&adc->lock);
        if (ret < 0)
                return ret;