linux-kernel - [PATCH v2 02/15] [media] lirc_dev: allow bufferless driver registration

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Date:	Fri, 01 Jul 2016 17:01:25 +0900
From:	Andi Shyti <andi.shyti@...sung.com>
To:	Mauro Carvalho Chehab <mchehab@....samsung.com>
Cc:	Joe Perches <joe@...ches.com>, Sean Young <sean@...s.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	Andi Shyti <andi.shyti@...sung.com>,
	Andi Shyti <andi@...zian.org>
Subject: [PATCH v2 02/15] [media] lirc_dev: allow bufferless driver registration

Some drivers don't necessarily need to have a FIFO managed buffer
for their transfers. Drivers now should call
lirc_register_bufferless_driver in order to handle the buffer
themselves.

The function works exaclty like lirc_register_driver except of
the buffer allocation.

Signed-off-by: Andi Shyti <andi.shyti@...sung.com>
---
 drivers/media/rc/lirc_dev.c | 44 ++++++++++++++++++++++++++++++++++----------
 include/media/lirc_dev.h    | 12 ++++++++++++
 2 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/drivers/media/rc/lirc_dev.c b/drivers/media/rc/lirc_dev.c
index 5716978..fa562a3 100644
--- a/drivers/media/rc/lirc_dev.c
+++ b/drivers/media/rc/lirc_dev.c
@@ -205,12 +205,14 @@ err_out:
 
 static int lirc_allocate_buffer(struct irctl *ir)
 {
-	int err;
+	int err = 0;
 	int bytes_in_key;
 	unsigned int chunk_size;
 	unsigned int buffer_size;
 	struct lirc_driver *d = &ir->d;
 
+	mutex_lock(&lirc_dev_lock);
+
 	bytes_in_key = BITS_TO_LONGS(d->code_length) +
 						(d->code_length % 8 ? 1 : 0);
 	buffer_size = d->buffer_size ? d->buffer_size : BUFLEN / bytes_in_key;
@@ -220,21 +222,26 @@ static int lirc_allocate_buffer(struct irctl *ir)
 		ir->buf = d->rbuf;
 	} else {
 		ir->buf = kmalloc(sizeof(struct lirc_buffer), GFP_KERNEL);
-		if (!ir->buf)
-			return -ENOMEM;
+		if (!ir->buf) {
+			err = -ENOMEM;
+			goto out;
+		}
 
 		err = lirc_buffer_init(ir->buf, chunk_size, buffer_size);
 		if (err) {
 			kfree(ir->buf);
-			return err;
+			goto out;
 		}
 	}
 	ir->chunk_size = ir->buf->chunk_size;
 
-	return 0;
+out:
+	mutex_unlock(&lirc_dev_lock);
+
+	return err;
 }
 
-int lirc_register_driver(struct lirc_driver *d)
+static int lirc_allocate_driver(struct lirc_driver *d)
 {
 	struct irctl *ir;
 	int minor;
@@ -342,10 +349,6 @@ int lirc_register_driver(struct lirc_driver *d)
 	/* some safety check 8-) */
 	d->name[sizeof(d->name)-1] = '\0';
 
-	err = lirc_allocate_buffer(ir);
-	if (err)
-		goto out_lock;
-
 	if (d->features == 0)
 		d->features = LIRC_CAN_REC_LIRCCODE;
 
@@ -385,8 +388,29 @@ out_lock:
 out:
 	return err;
 }
+
+int lirc_register_driver(struct lirc_driver *d)
+{
+	int err, minor;
+
+	minor = lirc_allocate_driver(d);
+	if (minor < 0)
+		return minor;
+
+	err = lirc_allocate_buffer(irctls[minor]);
+	if (err)
+		lirc_unregister_driver(minor);
+
+	return err ? err : minor;
+}
 EXPORT_SYMBOL(lirc_register_driver);
 
+int lirc_register_bufferless_driver(struct lirc_driver *d)
+{
+	return lirc_allocate_driver(d);
+}
+EXPORT_SYMBOL(lirc_register_bufferless_driver);
+
 int lirc_unregister_driver(int minor)
 {
 	struct irctl *ir;
diff --git a/include/media/lirc_dev.h b/include/media/lirc_dev.h
index 0ab59a5..8bed57a 100644
--- a/include/media/lirc_dev.h
+++ b/include/media/lirc_dev.h
@@ -214,6 +214,18 @@ struct lirc_driver {
  */
 extern int lirc_register_driver(struct lirc_driver *d);
 
+/* int lirc_register_bufferless_driver - allocates a lirc bufferless driver
+ * @d: reference to the lirc_driver to initialize
+ *
+ * The difference between lirc_register_driver and
+ * lirc_register_bufferless_driver is that the latter doesn't allocate any
+ * buffer, which means that the driver using the lirc_driver should take care of
+ * it by itself.
+ *
+ * returns 0 on success or a the negative errno number in case of failure.
+ */
+extern int lirc_register_bufferless_driver(struct lirc_driver *d);
+
 /* returns negative value on error or 0 if success
 */
 extern int lirc_unregister_driver(int minor);
-- 
2.8.1