[PATCH v3 5/8] iio: adc: ti-adc128s052: Simplify using guard(mutex)

Matti Vaittinen
2025-04-07T11:36:42Z

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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>

---
Revision history:
v2 =>
- No changes
v1 => v2:
- Protect the shared message data
- Add message data protection to the mutex doc
- Reword the commit message
---
drivers/iio/adc/ti-adc128s052.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
index d90a5caa028f..fa0099356be7 100644
--- 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;