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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136// SPDX-License-Identifier: GPL-2.0/* * media-dev-allocator.c - Media Controller Device Allocator API * * Copyright (c) 2019 Shuah Khan <shuah@kernel.org> * * 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/kref.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/usb.h>
#include <media/media-device.h>#include <media/media-dev-allocator.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 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: releasing Media Device\n", __func__);
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, const char *module_name, struct module *owner){ struct media_device_instance *mdi;
list_for_each_entry(mdi, &media_device_list, list) { if (mdi->mdev.dev != dev) continue;
kref_get(&mdi->refcount);
/* get module reference for the media_device owner */ if (owner != mdi->owner && !try_module_get(mdi->owner)) dev_err(dev, "%s: module %s get owner reference error\n", __func__, module_name); else dev_dbg(dev, "%s: module %s got owner reference\n", __func__, module_name); return &mdi->mdev; }
mdi = kzalloc_obj(*mdi); if (!mdi) return NULL;
mdi->owner = owner; kref_init(&mdi->refcount); list_add_tail(&mdi->list, &media_device_list);
dev_dbg(dev, "%s: Allocated media device for owner %s\n", __func__, module_name); return &mdi->mdev;}
struct media_device *media_device_usb_allocate(struct usb_device *udev, const char *module_name, struct module *owner){ struct media_device *mdev;
mutex_lock(&media_device_lock); mdev = __media_device_get(&udev->dev, module_name, owner); 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); return mdev;}EXPORT_SYMBOL_GPL(media_device_usb_allocate);
void media_device_delete(struct media_device *mdev, const char *module_name, struct module *owner){ struct media_device_instance *mdi = to_media_device_instance(mdev);
mutex_lock(&media_device_lock); /* put module reference for the media_device owner */ if (mdi->owner != owner) { module_put(mdi->owner); dev_dbg(mdi->mdev.dev, "%s: module %s put owner module reference\n", __func__, module_name); } mutex_unlock(&media_device_lock); kref_put(&mdi->refcount, media_device_instance_release);}EXPORT_SYMBOL_GPL(media_device_delete);