[PATCH 1/2] uio: add resource managed devm_uio_register_device() function

[PATCH 1/2] uio: add resource managed devm_uio_register_device() function

[Alexandru Ardelean]

This change adds a resource managed equivalent of uio_register_device().
Not adding devm_uio_unregister_device(), since the intent is to discourage
it's usage. Having such a function may allow some bad driver designs. Most
users of devm_*register*() functions rarely use the unregister equivalents.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
 drivers/uio/uio.c          | 38 ++++++++++++++++++++++++++++++++++++++
 include/linux/uio_driver.h |  9 +++++++++
 2 files changed, 47 insertions(+)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index a57698985f9c..6e725c6c6256 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -996,6 +996,44 @@ int __uio_register_device(struct module *owner,
 }
 EXPORT_SYMBOL_GPL(__uio_register_device);
 
+static void devm_uio_unregister_device(struct device *dev, void *res)
+{
+	uio_unregister_device(*(struct uio_info **)res);
+}
+
+/**
+ * devm_uio_register_device - Resource managed uio_register_device()
+ * @owner:	module that creates the new device
+ * @parent:	parent device
+ * @info:	UIO device capabilities
+ *
+ * returns zero on success or a negative error code.
+ */
+int __devm_uio_register_device(struct module *owner,
+			       struct device *parent,
+			       struct uio_info *info)
+{
+	struct uio_info **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_uio_unregister_device, sizeof(*ptr),
+			   GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	*ptr = info;
+	ret = __uio_register_device(owner, parent, info);
+	if (ret) {
+		devres_free(ptr);
+		return ret;
+	}
+
+	devres_add(parent, ptr);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__devm_uio_register_device);
+
 /**
  * uio_unregister_device - unregister a industrial IO device
  * @info:	UIO device capabilities
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 01081c4726c0..c5a306bd458c 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -123,6 +123,15 @@ extern int __must_check
 extern void uio_unregister_device(struct uio_info *info);
 extern void uio_event_notify(struct uio_info *info);
 
+extern int __must_check
+	__devm_uio_register_device(struct module *owner,
+				   struct device *parent,
+				   struct uio_info *info);
+
+/* use a define to avoid include chaining to get THIS_MODULE */
+#define devm_uio_register_device(parent, info) \
+	__devm_uio_register_device(THIS_MODULE, parent, info)
+
 /* defines for uio_info->irq */
 #define UIO_IRQ_CUSTOM	-1
 #define UIO_IRQ_NONE	0
-- 
2.20.1

[PATCH 2/2] uio: uio_pdrv_genirq: use new devm_uio_register_device() function

[Alexandru Ardelean]

This change makes use of the new devm_uio_register_device() initializer.
This cleans up the exit path quite nicely, and removes the remove function
of the driver.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
 drivers/uio/uio_pdrv_genirq.c | 34 ++++++++++++++--------------------
 1 file changed, 14 insertions(+), 20 deletions(-)

diff --git a/drivers/uio/uio_pdrv_genirq.c b/drivers/uio/uio_pdrv_genirq.c
index fc25ce90da3b..ae319ef3a832 100644
--- a/drivers/uio/uio_pdrv_genirq.c
+++ b/drivers/uio/uio_pdrv_genirq.c
@@ -99,6 +99,13 @@ static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
 	return 0;
 }
 
+static void uio_pdrv_genirq_cleanup(void *data)
+{
+	struct device *dev = data;
+
+	pm_runtime_disable(dev);
+}
+
 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
 {
 	struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
@@ -213,28 +220,16 @@ static int uio_pdrv_genirq_probe(struct platform_device *pdev)
 	 */
 	pm_runtime_enable(&pdev->dev);
 
-	ret = uio_register_device(&pdev->dev, priv->uioinfo);
-	if (ret) {
-		dev_err(&pdev->dev, "unable to register uio device\n");
-		pm_runtime_disable(&pdev->dev);
+	ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup,
+				       &pdev->dev);
+	if (ret)
 		return ret;
-	}
-
-	platform_set_drvdata(pdev, priv);
-	return 0;
-}
-
-static int uio_pdrv_genirq_remove(struct platform_device *pdev)
-{
-	struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 
-	uio_unregister_device(priv->uioinfo);
-	pm_runtime_disable(&pdev->dev);
-
-	priv->uioinfo->handler = NULL;
-	priv->uioinfo->irqcontrol = NULL;
+	ret = devm_uio_register_device(&pdev->dev, priv->uioinfo);
+	if (ret)
+		dev_err(&pdev->dev, "unable to register uio device\n");
 
-	return 0;
+	return ret;
 }
 
 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
@@ -271,7 +266,6 @@ MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
 
 static struct platform_driver uio_pdrv_genirq = {
 	.probe = uio_pdrv_genirq_probe,
-	.remove = uio_pdrv_genirq_remove,
 	.driver = {
 		.name = DRIVER_NAME,
 		.pm = &uio_pdrv_genirq_dev_pm_ops,
-- 
2.20.1