linux-kernel - [PATCH 1/3] iio: adc: ti_am335x_adc: alloc channels via devm

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Date:   Tue, 28 Apr 2020 14:14:28 +0300
From:   Alexandru Ardelean <alexandru.ardelean@...log.com>
To:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <jic23@...nel.org>, <rachna@...com>, <mugunthanvnm@...com>,
        <vigneshr@...com>, <afd@...com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>
Subject: [PATCH 1/3] iio: adc: ti_am335x_adc: alloc channels via devm_kcalloc()

This change attaches the life-cycle of the channels array to the parent
device object that is attached to the IIO device.
This way we can remove from the cleanup code, the explicit
tiadc_channels_remove() which simply does a kfree() on the channels array.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
---

The reason I'm targetting this driver, is because it's among the few
places where 'indio_dev->buffer' is accessed directly in the driver, and
that makes it difficult to think of a sane-backwards-compatible way to
do multiple IIO buffers.

 drivers/iio/adc/ti_am335x_adc.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index 9d984f2a8ba7..d932fe383a24 100644
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -428,7 +428,8 @@ static const char * const chan_name_ain[] = {
 	"AIN7",
 };
 
-static int tiadc_channel_init(struct iio_dev *indio_dev, int channels)
+static int tiadc_channel_init(struct device *dev, struct iio_dev *indio_dev,
+			      int channels)
 {
 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
 	struct iio_chan_spec *chan_array;
@@ -436,7 +437,8 @@ static int tiadc_channel_init(struct iio_dev *indio_dev, int channels)
 	int i;
 
 	indio_dev->num_channels = channels;
-	chan_array = kcalloc(channels, sizeof(*chan_array), GFP_KERNEL);
+	chan_array = devm_kcalloc(dev, channels, sizeof(*chan_array),
+				  GFP_KERNEL);
 	if (chan_array == NULL)
 		return -ENOMEM;
 
@@ -459,11 +461,6 @@ static int tiadc_channel_init(struct iio_dev *indio_dev, int channels)
 	return 0;
 }
 
-static void tiadc_channels_remove(struct iio_dev *indio_dev)
-{
-	kfree(indio_dev->channels);
-}
-
 static int tiadc_read_raw(struct iio_dev *indio_dev,
 		struct iio_chan_spec const *chan,
 		int *val, int *val2, long mask)
@@ -635,7 +632,7 @@ static int tiadc_probe(struct platform_device *pdev)
 	tiadc_writel(adc_dev, REG_FIFO1THR, FIFO1_THRESHOLD);
 	mutex_init(&adc_dev->fifo1_lock);
 
-	err = tiadc_channel_init(indio_dev, adc_dev->channels);
+	err = tiadc_channel_init(&pdev->dev, indio_dev, adc_dev->channels);
 	if (err < 0)
 		return err;
 
@@ -666,7 +663,6 @@ static int tiadc_probe(struct platform_device *pdev)
 err_buffer_unregister:
 	tiadc_iio_buffered_hardware_remove(indio_dev);
 err_free_channels:
-	tiadc_channels_remove(indio_dev);
 	return err;
 }
 
@@ -684,7 +680,6 @@ static int tiadc_remove(struct platform_device *pdev)
 	}
 	iio_device_unregister(indio_dev);
 	tiadc_iio_buffered_hardware_remove(indio_dev);
-	tiadc_channels_remove(indio_dev);
 
 	step_en = get_adc_step_mask(adc_dev);
 	am335x_tsc_se_clr(adc_dev->mfd_tscadc, step_en);
-- 
2.17.1