linux-kernel - [PATCH v12 4/8] iio: buffer-dmaengine: add dev-managed calls for buffer alloc

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Date:   Sun, 22 Mar 2020 19:53:21 +0200
From:   Alexandru Ardelean <alexandru.ardelean@...log.com>
To:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>
CC:     <jic23@...nel.org>, <robh+dt@...nel.org>, <Laszlo.Nagy@...log.com>,
        <Andrei.Grozav@...log.com>, <Michael.Hennerich@...log.com>,
        <Istvan.Csomortani@...log.com>, <Adrian.Costina@...log.com>,
        <Dragos.Bogdan@...log.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>
Subject: [PATCH v12 4/8] iio: buffer-dmaengine: add dev-managed calls for buffer alloc

Currently, when using a 'iio_dmaengine_buffer_alloc()', an matching call to
'iio_dmaengine_buffer_free()' must be made.

With this change, this can be avoided by using
'devm_iio_dmaengine_buffer_alloc()'. The buffer will get free'd via the
device's devres handling.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
---
 .../buffer/industrialio-buffer-dmaengine.c    | 39 +++++++++++++++++++
 include/linux/iio/buffer-dmaengine.h          |  3 ++
 2 files changed, 42 insertions(+)

diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
index 94da3b1ca3a2..6dedf12b69a4 100644
--- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c
+++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
@@ -229,6 +229,45 @@ void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
 }
 EXPORT_SYMBOL_GPL(iio_dmaengine_buffer_free);
 
+static void __devm_iio_dmaengine_buffer_free(struct device *dev, void *res)
+{
+	iio_dmaengine_buffer_free(*(struct iio_buffer **)res);
+}
+
+/**
+ * devm_iio_dmaengine_buffer_alloc() - Resource-managed iio_dmaengine_buffer_alloc()
+ * @dev: Parent device for the buffer
+ * @channel: DMA channel name, typically "rx".
+ *
+ * This allocates a new IIO buffer which internally uses the DMAengine framework
+ * to perform its transfers. The parent device will be used to request the DMA
+ * channel.
+ *
+ * The buffer will be automatically de-allocated once the device gets destroyed.
+ */
+struct iio_buffer *devm_iio_dmaengine_buffer_alloc(struct device *dev,
+	const char *channel)
+{
+	struct iio_buffer **bufferp, *buffer;
+
+	bufferp = devres_alloc(__devm_iio_dmaengine_buffer_free,
+			       sizeof(*bufferp), GFP_KERNEL);
+	if (!bufferp)
+		return ERR_PTR(-ENOMEM);
+
+	buffer = iio_dmaengine_buffer_alloc(dev, channel);
+	if (IS_ERR(buffer)) {
+		devres_free(bufferp);
+		return buffer;
+	}
+
+	*bufferp = buffer;
+	devres_add(dev, bufferp);
+
+	return buffer;
+}
+EXPORT_SYMBOL_GPL(devm_iio_dmaengine_buffer_alloc);
+
 MODULE_AUTHOR("Lars-Peter Clausen <lars@...afoo.de>");
 MODULE_DESCRIPTION("DMA buffer for the IIO framework");
 MODULE_LICENSE("GPL");
diff --git a/include/linux/iio/buffer-dmaengine.h b/include/linux/iio/buffer-dmaengine.h
index b3a57444a886..0e503db71289 100644
--- a/include/linux/iio/buffer-dmaengine.h
+++ b/include/linux/iio/buffer-dmaengine.h
@@ -14,4 +14,7 @@ struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
 	const char *channel);
 void iio_dmaengine_buffer_free(struct iio_buffer *buffer);
 
+struct iio_buffer *devm_iio_dmaengine_buffer_alloc(struct device *dev,
+						   const char *channel);
+
 #endif
-- 
2.17.1