[PATCH v5 3/3] iio: adc: ingenic-adc: use guard()() and scoped_guard() to handle synchronisation

[Felipe Ribeiro de Souza <felipers@ime.usp.br>]

Replace mutex_lock() and mutex_unlock() calls with guard()() in
functions ingenic_adc_set_adcmd(), ingenic_adc_set_config(),
ingenic_adc_enable(), ingenic_adc_capture(), and with scoped_guard()
in function ingenic_adc_read_chan_info_raw().

This removes the need to call the unlock function, as the lock is
automatically released when the function return or the scope exits
for any other case.

Signed-off-by: Felipe Ribeiro de Souza <felipers@ime.usp.br>
Co-developed-by: Lucas Ivars Cadima Ciziks <lucas@ciziks.com>
Signed-off-by: Lucas Ivars Cadima Ciziks <lucas@ciziks.com>

---
v2:
  - Adjust order of #include.
  - Replace guard() in ingenic_adc_read_chan_info_raw() by scoped_guard()
    to preserve original behavior.
v3:
  - Split out ingenic_adc_read_chan_info_raw() logic to helper function.
v4:
  - Adjust code style for better readability.
v5:
  - Rename ingenic_adc_enable_unlocked() to __ingenic_adc_enable() and
    ingenic_adc_read_chan_locked() to __ingenic_adc_read_chan() to keep
    the convention about the locked functions name.
  - Move the mutex lock back to ingenic_adc_read_chan_info_raw().
---
 drivers/iio/adc/ingenic-adc.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/iio/adc/ingenic-adc.c b/drivers/iio/adc/ingenic-adc.c
index 91e3ea6615942..414f69acab7b3 100644
--- a/drivers/iio/adc/ingenic-adc.c
+++ b/drivers/iio/adc/ingenic-adc.c
@@ -7,6 +7,8 @@
  */
 
 #include <dt-bindings/iio/adc/ingenic,adc.h>
+
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/iio.h>
@@ -115,7 +117,7 @@ static void ingenic_adc_set_adcmd(struct iio_dev *iio_dev, unsigned long mask)
 {
 	struct ingenic_adc *adc = iio_priv(iio_dev);
 
-	mutex_lock(&adc->lock);
+	guard(mutex)(&adc->lock);
 
 	/* Init ADCMD */
 	readl(adc->base + JZ_ADC_REG_ADCMD);
@@ -162,8 +164,6 @@ static void ingenic_adc_set_adcmd(struct iio_dev *iio_dev, unsigned long mask)
 
 	/* We're done */
 	writel(0, adc->base + JZ_ADC_REG_ADCMD);
-
-	mutex_unlock(&adc->lock);
 }
 
 static void ingenic_adc_set_config(struct ingenic_adc *adc,
@@ -172,13 +172,11 @@ static void ingenic_adc_set_config(struct ingenic_adc *adc,
 {
 	uint32_t cfg;
 
-	mutex_lock(&adc->lock);
+	guard(mutex)(&adc->lock);
 
 	cfg = readl(adc->base + JZ_ADC_REG_CFG) & ~mask;
 	cfg |= val;
 	writel(cfg, adc->base + JZ_ADC_REG_CFG);
-
-	mutex_unlock(&adc->lock);
 }
 
 static void __ingenic_adc_enable(struct ingenic_adc *adc, int engine,
@@ -200,9 +198,8 @@ static void ingenic_adc_enable(struct ingenic_adc *adc,
 			       int engine,
 			       bool enabled)
 {
-	mutex_lock(&adc->lock);
+	guard(mutex)(&adc->lock);
 	__ingenic_adc_enable(adc, engine, enabled);
-	mutex_unlock(&adc->lock);
 }
 
 static int ingenic_adc_capture(struct ingenic_adc *adc,
@@ -217,7 +214,7 @@ static int ingenic_adc_capture(struct ingenic_adc *adc,
 	 * probably due to the switch of VREF. We must keep the lock here to
 	 * avoid races with the buffer enable/disable functions.
 	 */
-	mutex_lock(&adc->lock);
+	guard(mutex)(&adc->lock);
 	cfg = readl(adc->base + JZ_ADC_REG_CFG);
 	writel(cfg & ~JZ_ADC_REG_CFG_CMD_SEL, adc->base + JZ_ADC_REG_CFG);
 
@@ -228,7 +225,6 @@ static int ingenic_adc_capture(struct ingenic_adc *adc,
 		__ingenic_adc_enable(adc, engine, false);
 
 	writel(cfg, adc->base + JZ_ADC_REG_CFG);
-	mutex_unlock(&adc->lock);
 
 	return ret;
 }
@@ -681,9 +677,8 @@ static int ingenic_adc_read_chan_info_raw(struct iio_dev *iio_dev,
 	}
 
 	/* We cannot sample the aux channels in parallel. */
-	mutex_lock(&adc->aux_lock);
-	ret = __ingenic_adc_read_chan(adc, chan, val);
-	mutex_unlock(&adc->aux_lock);
+	scoped_guard(mutex, &adc->aux_lock)
+		ret = __ingenic_adc_read_chan(adc, chan, val);
 
 	clk_disable(adc->clk);
 
-- 
2.43.0