uio: add resource managed devm_uio_register_device() function

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>
Link: https://lore.kernel.org/r/20200306161853.25368-1-alexandru.ardelean@analog.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index a576989..6e725c6 100644 (file)
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -996,6 +996,44 @@ err_device_create:
 }
 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 461db05..54bf6b1 100644 (file)
--- 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