[PATCH 1/2] UIO: add device clock support

[Daniel Mack <daniel@caiaq.de>]

Add a pointer to a 'struct clk' to uio_info. Drivers can set
this pointer if a clock is needed, and the UIO core will care
to enable and disable it upon device open and release.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Hans J. Koch <hjk@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
---
 drivers/uio/uio.c          |   15 ++++++++++++++-
 include/linux/uio_driver.h |    2 ++
 2 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 03efb06..6ba95cf 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -479,6 +479,12 @@ static int uio_open(struct inode *inode, struct file *filep)
 	listener->event_count = atomic_read(&idev->event);
 	filep->private_data = listener;
 
+	if (idev->info->clk) {
+		ret = clk_enable(idev->info->clk);
+		if (ret)
+			goto err_clkenable;
+	}
+
 	if (idev->info->open) {
 		ret = idev->info->open(idev->info, inode);
 		if (ret)
@@ -486,6 +492,7 @@ static int uio_open(struct inode *inode, struct file *filep)
 	}
 	return 0;
 
+err_clkenable:
 err_infoopen:
 	kfree(listener);
 
@@ -510,8 +517,14 @@ static int uio_release(struct inode *inode, struct file *filep)
 	struct uio_listener *listener = filep->private_data;
 	struct uio_device *idev = listener->dev;
 
-	if (idev->info->release)
+	if (idev->info->release) {
 		ret = idev->info->release(idev->info, inode);
+		if (ret)
+			dev_err(idev->dev, "release() failed (%d)\n", ret);
+	}
+
+	if (idev->info->clk)
+		clk_disable(idev->info->clk);
 
 	module_put(idev->owner);
 	kfree(listener);
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 5dcc9ff..6bc0e7e 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/interrupt.h>
+#include <linux/clk.h>
 
 struct uio_map;
 
@@ -87,6 +88,7 @@ struct uio_info {
 	long			irq;
 	unsigned long		irq_flags;
 	void			*priv;
+	struct clk		*clk;
 	irqreturn_t (*handler)(int irq, struct uio_info *dev_info);
 	int (*mmap)(struct uio_info *info, struct vm_area_struct *vma);
 	int (*open)(struct uio_info *info, struct inode *inode);
-- 
1.6.3.1