diff options
Diffstat (limited to 'linux')
| -rw-r--r-- | linux/Documentation/video4linux/v4l2-framework.txt | 28 | ||||
| -rw-r--r-- | linux/drivers/media/video/cx18/cx18-driver.c | 2 | ||||
| -rw-r--r-- | linux/drivers/media/video/cx18/cx18-streams.c | 4 | ||||
| -rw-r--r-- | linux/drivers/media/video/ivtv/ivtv-driver.c | 2 | ||||
| -rw-r--r-- | linux/drivers/media/video/ivtv/ivtv-streams.c | 4 | ||||
| -rw-r--r-- | linux/drivers/media/video/v4l2-dev.c | 103 | ||||
| -rw-r--r-- | linux/include/media/v4l2-dev.h | 4 |
7 files changed, 112 insertions, 35 deletions
diff --git a/linux/Documentation/video4linux/v4l2-framework.txt b/linux/Documentation/video4linux/v4l2-framework.txt index cb6c7eb51..b806edaf3 100644 --- a/linux/Documentation/video4linux/v4l2-framework.txt +++ b/linux/Documentation/video4linux/v4l2-framework.txt @@ -486,17 +486,27 @@ VFL_TYPE_RADIO: radioX for radio tuners VFL_TYPE_VTX: vtxX for teletext devices (deprecated, don't use) The last argument gives you a certain amount of control over the device -kernel number used (i.e. the X in videoX). Normally you will pass -1 to -let the v4l2 framework pick the first free number. But if a driver creates -many devices, then it can be useful to have different video devices in -separate ranges. For example, video capture devices start at 0, video -output devices start at 16. - -So you can use the last argument to specify a minimum kernel number and -the v4l2 framework will try to pick the first free number that is equal +device node number used (i.e. the X in videoX). Normally you will pass -1 +to let the v4l2 framework pick the first free number. But sometimes users +want to select a specific node number. It is common that drivers allow +the user to select a specific device node number through a driver module +option. That number is then passed to this function and video_register_device +will attempt to select that device node number. If that number was already +in use, then the next free device node number will be selected and it +will send a warning to the kernel log. + +Another use-case is if a driver creates many devices. In that case it can +be useful to place different video devices in separate ranges. For example, +video capture devices start at 0, video output devices start at 16. +So you can use the last argument to specify a minimum device node number +and the v4l2 framework will try to pick the first free number that is equal or higher to what you passed. If that fails, then it will just pick the first free number. +Since in this case you do not care about a warning about not being able +to select the specified device node number, you can call the function +video_register_device_no_warn() instead. + Whenever a device node is created some attributes are also created for you. If you look in /sys/class/video4linux you see the devices. Go into e.g. video0 and you will see 'name' and 'index' attributes. The 'name' attribute @@ -513,7 +523,7 @@ After the device was successfully registered, then you can use these fields: - vfl_type: the device type passed to video_register_device. - minor: the assigned device minor number. -- num: the device kernel number (i.e. the X in videoX). +- num: the device node number (i.e. the X in videoX). - index: the device index number. If the registration failed, then you need to call video_device_release() diff --git a/linux/drivers/media/video/cx18/cx18-driver.c b/linux/drivers/media/video/cx18/cx18-driver.c index ae13a1546..ede519748 100644 --- a/linux/drivers/media/video/cx18/cx18-driver.c +++ b/linux/drivers/media/video/cx18/cx18-driver.c @@ -231,7 +231,7 @@ MODULE_PARM_DESC(enc_pcm_bufs, "Number of encoder PCM buffers\n" "\t\t\tDefault is computed from other enc_pcm_* parameters"); -MODULE_PARM_DESC(cx18_first_minor, "Set kernel number assigned to first card"); +MODULE_PARM_DESC(cx18_first_minor, "Set device node number assigned to first card"); MODULE_AUTHOR("Hans Verkuil"); MODULE_DESCRIPTION("CX23418 driver"); diff --git a/linux/drivers/media/video/cx18/cx18-streams.c b/linux/drivers/media/video/cx18/cx18-streams.c index c134927b3..dabe3fadc 100644 --- a/linux/drivers/media/video/cx18/cx18-streams.c +++ b/linux/drivers/media/video/cx18/cx18-streams.c @@ -250,9 +250,9 @@ static int cx18_reg_dev(struct cx18 *cx, int type) video_set_drvdata(s->video_dev, s); /* Register device. First try the desired minor, then any free one. */ - ret = video_register_device(s->video_dev, vfl_type, num); + ret = video_register_device_no_warn(s->video_dev, vfl_type, num); if (ret < 0) { - CX18_ERR("Couldn't register v4l2 device for %s kernel number %d\n", + CX18_ERR("Couldn't register v4l2 device for %s (device node number %d)\n", s->name, num); video_device_release(s->video_dev); s->video_dev = NULL; diff --git a/linux/drivers/media/video/ivtv/ivtv-driver.c b/linux/drivers/media/video/ivtv/ivtv-driver.c index fbb8586c5..383d401b4 100644 --- a/linux/drivers/media/video/ivtv/ivtv-driver.c +++ b/linux/drivers/media/video/ivtv/ivtv-driver.c @@ -246,7 +246,7 @@ MODULE_PARM_DESC(newi2c, "\t\t\t-1 is autodetect, 0 is off, 1 is on\n" "\t\t\tDefault is autodetect"); -MODULE_PARM_DESC(ivtv_first_minor, "Set kernel number assigned to first card"); +MODULE_PARM_DESC(ivtv_first_minor, "Set device node number assigned to first card"); MODULE_AUTHOR("Kevin Thayer, Chris Kennedy, Hans Verkuil"); MODULE_DESCRIPTION("CX23415/CX23416 driver"); diff --git a/linux/drivers/media/video/ivtv/ivtv-streams.c b/linux/drivers/media/video/ivtv/ivtv-streams.c index 15da01710..67699e3f2 100644 --- a/linux/drivers/media/video/ivtv/ivtv-streams.c +++ b/linux/drivers/media/video/ivtv/ivtv-streams.c @@ -261,8 +261,8 @@ static int ivtv_reg_dev(struct ivtv *itv, int type) video_set_drvdata(s->vdev, s); /* Register device. First try the desired minor, then any free one. */ - if (video_register_device(s->vdev, vfl_type, num)) { - IVTV_ERR("Couldn't register v4l2 device for %s kernel number %d\n", + if (video_register_device_no_warn(s->vdev, vfl_type, num)) { + IVTV_ERR("Couldn't register v4l2 device for %s (device node number %d)\n", s->name, num); video_device_release(s->vdev); s->vdev = NULL; diff --git a/linux/drivers/media/video/v4l2-dev.c b/linux/drivers/media/video/v4l2-dev.c index 9f04a8e6d..a6d761dec 100644 --- a/linux/drivers/media/video/v4l2-dev.c +++ b/linux/drivers/media/video/v4l2-dev.c @@ -86,7 +86,49 @@ static CLASS_DEVICE_ATTR(name, S_IRUGO, show_name, NULL); */ static struct video_device *video_device[VIDEO_NUM_DEVICES]; static DEFINE_MUTEX(videodev_lock); -static DECLARE_BITMAP(video_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES); +static DECLARE_BITMAP(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES); + +/* Device node utility functions */ + +/* Note: these utility functions all assume that vfl_type is in the range + [0, VFL_TYPE_MAX-1]. */ + +#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES +/* Return the bitmap corresponding to vfl_type. */ +static inline unsigned long *devnode_bits(int vfl_type) +{ + /* Any types not assigned to fixed minor ranges must be mapped to + one single bitmap for the purposes of finding a free node number + since all those unassigned types use the same minor range. */ + int idx = (vfl_type > VFL_TYPE_VTX) ? VFL_TYPE_MAX - 1 : vfl_type; + + return devnode_nums[idx]; +} +#else +/* Return the bitmap corresponding to vfl_type. */ +static inline unsigned long *devnode_bits(int vfl_type) +{ + return devnode_nums[vfl_type]; +} +#endif + +/* Mark device node number vdev->num as used */ +static inline void devnode_set(struct video_device *vdev) +{ + set_bit(vdev->num, devnode_bits(vdev->vfl_type)); +} + +/* Mark device node number vdev->num as unused */ +static inline void devnode_clear(struct video_device *vdev) +{ + clear_bit(vdev->num, devnode_bits(vdev->vfl_type)); +} + +/* Try to find a free device node number in the range [from, to> */ +static inline int devnode_find(struct video_device *vdev, int from, int to) +{ + return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from); +} struct video_device *video_device_alloc(void) { @@ -151,8 +193,8 @@ static void v4l2_device_release(struct device *cd) the release() callback. */ vdev->cdev = NULL; - /* Mark minor as free */ - clear_bit(vdev->num, video_nums[vdev->vfl_type]); + /* Mark device node number as free */ + devnode_clear(vdev); mutex_unlock(&videodev_lock); @@ -376,13 +418,16 @@ static int get_index(struct video_device *vdev) * video_register_device - register video4linux devices * @vdev: video device structure we want to register * @type: type of device to register - * @nr: which device number (0 == /dev/video0, 1 == /dev/video1, ... + * @nr: which device node number (0 == /dev/video0, 1 == /dev/video1, ... * -1 == first free) + * @warn_if_nr_in_use: warn if the desired device node number + * was already in use and another number was chosen instead. * - * The registration code assigns minor numbers based on the type - * requested. -ENFILE is returned in all the device slots for this - * category are full. If not then the minor field is set and the - * driver initialize function is called (if non %NULL). + * The registration code assigns minor numbers and device node numbers + * based on the requested type and registers the new device node with + * the kernel. + * An error is returned if no free minor or device node number could be + * found, or if the registration of the device node failed. * * Zero is returned on success. * @@ -396,7 +441,8 @@ static int get_index(struct video_device *vdev) * * %VFL_TYPE_RADIO - A radio card */ -int video_register_device(struct video_device *vdev, int type, int nr) +static int __video_register_device(struct video_device *vdev, int type, int nr, + int warn_if_nr_in_use) { int i = 0; int ret; @@ -439,7 +485,7 @@ int video_register_device(struct video_device *vdev, int type, int nr) if (vdev->v4l2_dev && vdev->v4l2_dev->dev) vdev->parent = vdev->v4l2_dev->dev; - /* Part 2: find a free minor, kernel number and device index. */ + /* Part 2: find a free minor, device node number and device index. */ #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES /* Keep the ranges for the first four types for historical * reasons. @@ -470,21 +516,22 @@ int video_register_device(struct video_device *vdev, int type, int nr) } #endif - /* Pick a minor number */ + /* Pick a device node number */ mutex_lock(&videodev_lock); - nr = find_next_zero_bit(video_nums[type], minor_cnt, nr == -1 ? 0 : nr); + nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt); if (nr == minor_cnt) - nr = find_first_zero_bit(video_nums[type], minor_cnt); + nr = devnode_find(vdev, 0, minor_cnt); if (nr == minor_cnt) { - printk(KERN_ERR "could not get a free kernel number\n"); + printk(KERN_ERR "could not get a free device node number\n"); mutex_unlock(&videodev_lock); return -ENFILE; } #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES - /* 1-on-1 mapping of kernel number to minor number */ + /* 1-on-1 mapping of device node number to minor number */ i = nr; #else - /* The kernel number and minor numbers are independent */ + /* The device node number and minor numbers are independent, so + we just find the first free minor number. */ for (i = 0; i < VIDEO_NUM_DEVICES; i++) if (video_device[i] == NULL) break; @@ -496,7 +543,8 @@ int video_register_device(struct video_device *vdev, int type, int nr) #endif vdev->minor = i + minor_offset; vdev->num = nr; - set_bit(nr, video_nums[type]); + devnode_set(vdev); + /* Should not happen since we thought this minor was free */ WARN_ON(video_device[vdev->minor] != NULL); vdev->index = get_index(vdev); @@ -538,12 +586,12 @@ int video_register_device(struct video_device *vdev, int type, int nr) #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 19) if (vdev->parent) vdev->dev.dev = vdev->parent; - sprintf(vdev->dev.class_id, "%s%d", name_base, nr); + sprintf(vdev->dev.class_id, "%s%d", name_base, vdev->num); ret = class_device_register(&vdev->dev); #else if (vdev->parent) vdev->dev.parent = vdev->parent; - dev_set_name(&vdev->dev, "%s%d", name_base, nr); + dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num); ret = device_register(&vdev->dev); #endif if (ret < 0) { @@ -570,6 +618,10 @@ int video_register_device(struct video_device *vdev, int type, int nr) reference to the device goes away. */ vdev->dev.release = v4l2_device_release; + if (nr != -1 && nr != vdev->num && warn_if_nr_in_use) + printk(KERN_WARNING "%s: requested %s%d, got %s%d\n", + __func__, name_base, nr, name_base, vdev->num); + /* Part 5: Activate this minor. The char device can now be used. */ mutex_lock(&videodev_lock); video_device[vdev->minor] = vdev; @@ -580,14 +632,25 @@ cleanup: mutex_lock(&videodev_lock); if (vdev->cdev) cdev_del(vdev->cdev); - clear_bit(vdev->num, video_nums[type]); + devnode_clear(vdev); mutex_unlock(&videodev_lock); /* Mark this video device as never having been registered. */ vdev->minor = -1; return ret; } + +int video_register_device(struct video_device *vdev, int type, int nr) +{ + return __video_register_device(vdev, type, nr, 1); +} EXPORT_SYMBOL(video_register_device); +int video_register_device_no_warn(struct video_device *vdev, int type, int nr) +{ + return __video_register_device(vdev, type, nr, 0); +} +EXPORT_SYMBOL(video_register_device_no_warn); + /** * video_unregister_device - unregister a video4linux device * @vdev: the device to unregister diff --git a/linux/include/media/v4l2-dev.h b/linux/include/media/v4l2-dev.h index 1cae97561..f813ae9c0 100644 --- a/linux/include/media/v4l2-dev.h +++ b/linux/include/media/v4l2-dev.h @@ -105,6 +105,10 @@ struct video_device Also note that vdev->minor is set to -1 if the registration failed. */ int __must_check video_register_device(struct video_device *vdev, int type, int nr); +/* Same as video_register_device, but no warning is issued if the desired + device node number was already in use. */ +int __must_check video_register_device_no_warn(struct video_device *vdev, int type, int nr); + /* Unregister video devices. Will do nothing if vdev == NULL or vdev->minor < 0. */ void video_unregister_device(struct video_device *vdev); |