Sorry for the duplicates. Replying to catch bounced emails on the original patch emails from git send-email
On 11/16/2016 07:29 AM, Shuah Khan wrote:
Media Device Allocator API to allows multiple drivers share a media device. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released.
Signed-off-by: Shuah Khan shuahkh@osg.samsung.com Reviewed-by: Hans Verkuil hans.verkuil@cisco.com
Changes since v3:
- Fixed undefined reference to `__media_device_usb_init compile error when CONFIG_USB is disabled.
- Fixed kernel paging error when accessing /dev/mediaX after rmmod of the module that owns the media_device. The fix bumps the reference count for the owner when second driver comes along to share the media_device. If au0828 owns the media_device, then snd_usb_audio will bump the refcount for au0828, so it won't get deleted and vice versa.
drivers/media/Makefile | 3 +- drivers/media/media-dev-allocator.c | 146 ++++++++++++++++++++++++++++++++++++ include/media/media-dev-allocator.h | 87 +++++++++++++++++++++ 3 files changed, 235 insertions(+), 1 deletion(-) create mode 100644 drivers/media/media-dev-allocator.c create mode 100644 include/media/media-dev-allocator.h
diff --git a/drivers/media/Makefile b/drivers/media/Makefile index 0deaa93..7c0701d 100644 --- a/drivers/media/Makefile +++ b/drivers/media/Makefile @@ -6,7 +6,8 @@ ifeq ($(CONFIG_MEDIA_CEC_EDID),y) obj-$(CONFIG_MEDIA_SUPPORT) += cec-edid.o endif
-media-objs := media-device.o media-devnode.o media-entity.o +media-objs := media-device.o media-devnode.o media-entity.o \
media-dev-allocator.o
# # I2C drivers should come before other drivers, otherwise they'll fail diff --git a/drivers/media/media-dev-allocator.c b/drivers/media/media-dev-allocator.c new file mode 100644 index 0000000..014a317 --- /dev/null +++ b/drivers/media/media-dev-allocator.c @@ -0,0 +1,146 @@ +/*
- media-dev-allocator.c - Media Controller Device Allocator API
- Copyright (c) 2016 Shuah Khan shuahkh@osg.samsung.com
- Copyright (c) 2016 Samsung Electronics Co., Ltd.
- This file is released under the GPLv2.
- Credits: Suggested by Laurent Pinchart laurent.pinchart@ideasonboard.com
- */
+/*
- This file adds a global refcounted Media Controller Device Instance API.
- A system wide global media device list is managed and each media device
- includes a kref count. The last put on the media device releases the media
- device instance.
- */
+#include <linux/slab.h> +#include <linux/kref.h> +#include <linux/usb.h> +#include <linux/module.h> +#include <media/media-device.h>
+static LIST_HEAD(media_device_list); +static DEFINE_MUTEX(media_device_lock);
+struct media_device_instance {
- struct media_device mdev;
- struct module *owner;
- struct list_head list;
- struct device *dev;
- struct kref refcount;
+};
+static inline struct media_device_instance * +to_media_device_instance(struct media_device *mdev) +{
- return container_of(mdev, struct media_device_instance, mdev);
+}
+static void media_device_instance_release(struct kref *kref) +{
- struct media_device_instance *mdi =
container_of(kref, struct media_device_instance, refcount);
- dev_dbg(mdi->mdev.dev, "%s: mdev=%p\n", __func__, &mdi->mdev);
- mutex_lock(&media_device_lock);
- media_device_unregister(&mdi->mdev);
- media_device_cleanup(&mdi->mdev);
- list_del(&mdi->list);
- mutex_unlock(&media_device_lock);
- kfree(mdi);
+}
+/* Callers should hold media_device_lock when calling this function */ +static struct media_device *__media_device_get(struct device *dev,
char *module_name)
+{
- struct media_device_instance *mdi;
- list_for_each_entry(mdi, &media_device_list, list) {
if (mdi->dev == dev) {
kref_get(&mdi->refcount);
/* get module reference for the media_device owner */
if (find_module(module_name) != mdi->owner &&
!try_module_get(mdi->owner))
dev_err(dev, "%s: try_module_get() error\n",
__func__);
dev_dbg(dev, "%s: get mdev=%p module_name %s\n",
__func__, &mdi->mdev, module_name);
return &mdi->mdev;
}
- }
- mdi = kzalloc(sizeof(*mdi), GFP_KERNEL);
- if (!mdi)
return NULL;
- mdi->dev = dev;
- mdi->owner = find_module(module_name);
- kref_init(&mdi->refcount);
- list_add_tail(&mdi->list, &media_device_list);
- dev_dbg(dev, "%s: alloc mdev=%p module_name %s\n", __func__,
&mdi->mdev, module_name);
- return &mdi->mdev;
+}
+#if IS_ENABLED(CONFIG_USB) +struct media_device *media_device_usb_allocate(struct usb_device *udev,
char *module_name)
+{
- struct media_device *mdev;
- if (!module_name) {
dev_err(&udev->dev, "%s Module Name is null\n", __func__);
return ERR_PTR(-EINVAL);
- }
- mutex_lock(&media_device_lock);
- mdev = __media_device_get(&udev->dev, module_name);
- if (!mdev) {
mutex_unlock(&media_device_lock);
return ERR_PTR(-ENOMEM);
- }
- /* check if media device is already initialized */
- if (!mdev->dev)
__media_device_usb_init(mdev, udev, udev->product,
module_name);
- mutex_unlock(&media_device_lock);
- dev_dbg(&udev->dev, "%s\n", __func__);
- return mdev;
+} +EXPORT_SYMBOL_GPL(media_device_usb_allocate); +#endif
+void media_device_delete(struct media_device *mdev, char *module_name) +{
- struct media_device_instance *mdi = to_media_device_instance(mdev);
- if (!module_name) {
dev_err(mdi->mdev.dev, "%s Module Name is null\n", __func__);
return;
- }
- dev_dbg(mdi->mdev.dev, "%s: mdev=%p module_name %s\n",
__func__, &mdi->mdev, module_name);
- mutex_lock(&media_device_lock);
- /* put module reference if media_device owner is not THIS_MODULE */
- if (mdi->owner != find_module(module_name)) {
module_put(mdi->owner);
dev_dbg(mdi->mdev.dev,
"%s decremented owner module reference\n", __func__);
- }
- mutex_unlock(&media_device_lock);
- kref_put(&mdi->refcount, media_device_instance_release);
+} +EXPORT_SYMBOL_GPL(media_device_delete); diff --git a/include/media/media-dev-allocator.h b/include/media/media-dev-allocator.h new file mode 100644 index 0000000..45c437d --- /dev/null +++ b/include/media/media-dev-allocator.h @@ -0,0 +1,87 @@ +/*
- media-dev-allocator.h - Media Controller Device Allocator API
- Copyright (c) 2016 Shuah Khan shuahkh@osg.samsung.com
- Copyright (c) 2016 Samsung Electronics Co., Ltd.
- This file is released under the GPLv2.
- Credits: Suggested by Laurent Pinchart laurent.pinchart@ideasonboard.com
- */
+/*
- This file adds a global ref-counted Media Controller Device Instance API.
- A system wide global media device list is managed and each media device
- includes a kref count. The last put on the media device releases the media
- device instance.
- */
+#ifndef _MEDIA_DEV_ALLOCTOR_H +#define _MEDIA_DEV_ALLOCTOR_H
+struct usb_device;
+#ifdef CONFIG_MEDIA_CONTROLLER +/**
- DOC: Media Controller Device Allocator API
- When media device belongs to more than one driver, the shared media device
- is allocated with the shared struct device as the key for look ups.
- Shared media device should stay in registered state until the last driver
- unregisters it. In addition, media device should be released when all the
- references are released. Each driver gets a reference to the media device
- during probe, when it allocates the media device. If media device is already
- allocated, allocate API bumps up the refcount and return the existing media
- device. Driver puts the reference back from its disconnect routine when it
- calls media_device_delete().
- Media device is unregistered and cleaned up from the kref put handler to
- ensure that the media device stays in registered state until the last driver
- unregisters the media device.
- Driver Usage:
- Drivers should use the media-core routines to get register reference and
- call media_device_delete() routine to make sure the shared media device
- delete is handled correctly.
- driver probe:
- Call media_device_usb_allocate() to allocate or get a reference
- Call media_device_register(), if media devnode isn't registered
- driver disconnect:
- Call media_device_delete() to free the media_device. Free'ing is
- handled by the put handler.
- */
+/**
- media_device_usb_allocate() - Allocate and return media device
- @udev - struct usb_device pointer
- @module_name
- This interface should be called to allocate a media device when multiple
- drivers share usb_device and the media device. This interface allocates
- media device and calls media_device_usb_init() to initialize it.
- */
+struct media_device *media_device_usb_allocate(struct usb_device *udev,
char *module_name);
+/**
- media_device_delete() - Release media device. Calls kref_put().
- @mdev - struct media_device pointer
- @module_name
- This interface should be called to put Media Device Instance kref.
- */
+void media_device_delete(struct media_device *mdev, char *driver_name); +#else +static inline struct media_device *media_device_usb_allocate(
struct usb_device *udev, char *driver_name)
{ return NULL; }
+static inline void media_device_delete(
struct media_device *mdev, char *module_name) { }
+#endif /* CONFIG_MEDIA_CONTROLLER */ +#endif