diff mbox series

[v3,3/4] ALSA: timer: Introduce virtual userspace-driven timers

Message ID 20240806125243.449959-4-ivan.orlov0322@gmail.com
State Superseded
Headers show
Series [v3,1/4] ALSA: aloop: Allow using global timers | expand

Commit Message

Ivan Orlov Aug. 6, 2024, 12:52 p.m. UTC
Implement two ioctl calls in order to support virtual userspace-driven
ALSA timers.

The first ioctl is SNDRV_TIMER_IOCTL_CREATE, which gets the
snd_utimer_info struct as a parameter and returns a file descriptor of
a virtual timer. It also updates the `id` field of the snd_utimer_info
struct, which provides a unique identifier for the timer (basically,
the subdevice number which can be used when creating timer instances).

This patch also introduces a tiny id allocator for the userspace-driven
timers, which guarantees that we don't have more than 128 of them in the
system.

Another ioctl is SNDRV_TIMER_IOCTL_TRIGGER, which allows us to trigger
the virtual timer (and calls snd_timer_interrupt for the timer under
the hood), causing all of the timer instances binded to this timer to
execute their callbacks.

The maximum amount of ticks available for the timer is 1 for the sake of
simplification of the userspace API. 'start', 'stop', 'open' and 'close'
callbacks for the userspace-driven timers are empty since we don't
really do any hardware initialization here.

Suggested-by: Axel Holzinger <aholzinger@gmx.de>
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
---
V1 -> V2:
- Add missing kfree for the utimer name in snd_utimer_free
- Remove extra newline in sound core Kconfig
- Use IDA allocator API to allocate utimer ids
- Use kasprintf for the timer name instead of kzalloc + sprintf
V2 -> V3:
- Use __u64 instead of snd_pcm_uframes_t in snd_utimer_info struct
- Add 16 reserved bytes to snd_utimer_info struct just in case we decide
to add some other fields to this struct
- Bump the timer protocol version in SNDRV_TIMER_VERSION to 2.0.8
- Make the 'snd_utimer_ids' variable static
- Add sanity checks to the 'snd_utimer_create' function: 0-check for
period size and frame rate, overflow and 0- checks for resolution
- Use automatic cleanup in 'snd_utimer_ioctl_create'
- Return -ENOTTY instead of -EINVAL from ioctl if userspace-driven
timers are disabled

 include/uapi/sound/asound.h |  20 +++-
 sound/core/Kconfig          |  10 ++
 sound/core/timer.c          | 221 ++++++++++++++++++++++++++++++++++++
 3 files changed, 250 insertions(+), 1 deletion(-)

Comments

kernel test robot Aug. 8, 2024, 9:22 a.m. UTC | #1
Hi Ivan,

kernel test robot noticed the following build errors:

[auto build test ERROR on tiwai-sound/for-next]
[also build test ERROR on tiwai-sound/for-linus linus/master v6.11-rc2 next-20240808]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Ivan-Orlov/ALSA-aloop-Allow-using-global-timers/20240806-210332
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git for-next
patch link:    https://lore.kernel.org/r/20240806125243.449959-4-ivan.orlov0322%40gmail.com
patch subject: [PATCH v3 3/4] ALSA: timer: Introduce virtual userspace-driven timers
config: arm-randconfig-r064-20240807 (https://download.01.org/0day-ci/archive/20240808/202408081612.hvfwzVlB-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240808/202408081612.hvfwzVlB-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408081612.hvfwzVlB-lkp@intel.com/

All errors (new ones prefixed by >>):

   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_usb_submit_wmt_recv_urb':
   drivers/bluetooth/btmtk.c:531:(.text+0x6c2): undefined reference to `usb_alloc_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:537:(.text+0x6e6): undefined reference to `usb_free_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:561:(.text+0x750): undefined reference to `usb_anchor_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:562:(.text+0x75a): undefined reference to `usb_submit_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:567:(.text+0x796): undefined reference to `usb_unanchor_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:570:(.text+0x7a0): undefined reference to `usb_free_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_submit_intr_urb':
   drivers/bluetooth/btmtk.c:1174:(.text+0x80e): undefined reference to `usb_alloc_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:1181:(.text+0x83a): undefined reference to `usb_free_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:1195:(.text+0x8c4): undefined reference to `usb_anchor_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:1197:(.text+0x8cc): undefined reference to `usb_submit_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:1202:(.text+0x908): undefined reference to `usb_unanchor_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:1205:(.text+0x912): undefined reference to `usb_free_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_usb_suspend':
   drivers/bluetooth/btmtk.c:1265:(.text+0x988): undefined reference to `usb_kill_anchored_urbs'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_intr_complete':
   drivers/bluetooth/btmtk.c:1145:(.text+0xbf2): undefined reference to `usb_anchor_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:1147:(.text+0xbfc): undefined reference to `usb_submit_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:1157:(.text+0xc48): undefined reference to `usb_unanchor_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `__set_mtk_intr_interface':
   drivers/bluetooth/btmtk.c:991:(.text+0xcf4): undefined reference to `usb_set_interface'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_usb_isointf_init':
   drivers/bluetooth/btmtk.c:1224:(.text+0xd30): undefined reference to `usb_kill_anchored_urbs'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_usb_hci_wmt_sync':
   drivers/bluetooth/btmtk.c:610:(.text+0xf26): undefined reference to `usb_autopm_get_interface'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:618:(.text+0xf54): undefined reference to `usb_autopm_put_interface'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:625:(.text+0xf7e): undefined reference to `usb_autopm_put_interface'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_usb_reg_read':
   drivers/bluetooth/btmtk.c:790:(.text+0x1248): undefined reference to `usb_control_msg'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_usb_uhw_reg_write':
   drivers/bluetooth/btmtk.c:738:(.text+0x12e0): undefined reference to `usb_control_msg'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_usb_uhw_reg_read':
   drivers/bluetooth/btmtk.c:761:(.text+0x1374): undefined reference to `usb_control_msg'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_usb_recv_acl':
   drivers/bluetooth/btmtk.c:946:(.text+0x1e06): undefined reference to `usb_disable_autosuspend'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `btmtk_usb_wmt_recv':
   drivers/bluetooth/btmtk.c:508:(.text+0x1e72): undefined reference to `usb_anchor_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:509:(.text+0x1e7c): undefined reference to `usb_submit_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.c:518:(.text+0x1ec0): undefined reference to `usb_unanchor_urb'
   arm-linux-gnueabi-ld: drivers/bluetooth/btmtk.o: in function `alloc_mtk_intr_urb':
   drivers/bluetooth/btmtk.c:1037:(.text+0x1fc8): undefined reference to `usb_alloc_urb'
   arm-linux-gnueabi-ld: sound/core/timer.o: in function `snd_utimer_create':
>> sound/core/timer.c:2127:(.text+0x255c): undefined reference to `__aeabi_uldivmod'


vim +2127 sound/core/timer.c

  2112	
  2113	static int snd_utimer_create(struct snd_utimer_info *utimer_info,
  2114				     struct snd_utimer **r_utimer)
  2115	{
  2116		struct snd_utimer *utimer;
  2117		struct snd_timer *timer;
  2118		struct snd_timer_id tid;
  2119		int utimer_id;
  2120		int err = 0;
  2121		u64 resolution;
  2122	
  2123		if (!utimer_info || utimer_info->frame_rate == 0 || utimer_info->period_size == 0)
  2124			return -EINVAL;
  2125	
  2126		/* Let's check that we won't get an overflow in the resolution */
> 2127		if (NANO / utimer_info->frame_rate > U64_MAX / utimer_info->period_size)
  2128			return -EINVAL;
  2129	
  2130		resolution = NANO / utimer_info->frame_rate * utimer_info->period_size;
  2131	
  2132		if (resolution == 0)
  2133			return -EINVAL;
  2134	
  2135		utimer = kzalloc(sizeof(*utimer), GFP_KERNEL);
  2136		if (!utimer)
  2137			return -ENOMEM;
  2138	
  2139		/* We hold the ioctl lock here so we won't get a race condition when allocating id */
  2140		utimer_id = snd_utimer_take_id();
  2141		if (utimer_id < 0) {
  2142			err = utimer_id;
  2143			goto err_take_id;
  2144		}
  2145	
  2146		utimer->name = kasprintf(GFP_KERNEL, "snd-utimer%d", utimer_id);
  2147		if (!utimer->name) {
  2148			err = -ENOMEM;
  2149			goto err_get_name;
  2150		}
  2151	
  2152		utimer->id = utimer_id;
  2153	
  2154		tid.dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION;
  2155		tid.dev_class = SNDRV_TIMER_CLASS_GLOBAL;
  2156		tid.card = -1;
  2157		tid.device = SNDRV_TIMER_GLOBAL_UDRIVEN;
  2158		tid.subdevice = utimer_id;
  2159	
  2160		err = snd_timer_new(NULL, utimer->name, &tid, &timer);
  2161		if (err < 0) {
  2162			pr_err("Can't create userspace-driven timer\n");
  2163			goto err_timer_new;
  2164		}
  2165	
  2166		timer->module = THIS_MODULE;
  2167		timer->hw = timer_hw;
  2168		timer->hw.resolution = resolution;
  2169		timer->hw.ticks = 1;
  2170		timer->max_instances = MAX_SLAVE_INSTANCES;
  2171	
  2172		utimer->timer = timer;
  2173	
  2174		err = snd_timer_global_register(timer);
  2175		if (err < 0) {
  2176			pr_err("Can't register a userspace-driven timer\n");
  2177			goto err_timer_reg;
  2178		}
  2179	
  2180		*r_utimer = utimer;
  2181		return 0;
  2182	
  2183	err_timer_reg:
  2184		snd_timer_free(timer);
  2185	err_timer_new:
  2186		kfree(utimer->name);
  2187	err_get_name:
  2188		snd_utimer_put_id(utimer);
  2189	err_take_id:
  2190		kfree(utimer);
  2191	
  2192		return err;
  2193	}
  2194
diff mbox series

Patch

diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index 8bf7e8a0eb6f..cdd9cf8f71c1 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -869,7 +869,7 @@  struct snd_ump_block_info {
  *  Timer section - /dev/snd/timer
  */
 
-#define SNDRV_TIMER_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 7)
+#define SNDRV_TIMER_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 8)
 
 enum {
 	SNDRV_TIMER_CLASS_NONE = -1,
@@ -894,6 +894,7 @@  enum {
 #define SNDRV_TIMER_GLOBAL_RTC		1	/* unused */
 #define SNDRV_TIMER_GLOBAL_HPET		2
 #define SNDRV_TIMER_GLOBAL_HRTIMER	3
+#define SNDRV_TIMER_GLOBAL_UDRIVEN	4
 
 /* info flags */
 #define SNDRV_TIMER_FLG_SLAVE		(1<<0)	/* cannot be controlled */
@@ -974,6 +975,21 @@  struct snd_timer_status {
 };
 #endif
 
+/*
+ * This structure describes the userspace-driven timer. Such timers are purely virtual,
+ * and can only be triggered from software (for instance, by userspace application).
+ */
+struct snd_utimer_info {
+	/*
+	 * To pretend being a normal timer, we need to know the frame rate and
+	 * the period size in frames.
+	 */
+	__u64 frame_rate;
+	__u64 period_size;
+	unsigned int id;
+	unsigned char reserved[16];
+};
+
 #define SNDRV_TIMER_IOCTL_PVERSION	_IOR('T', 0x00, int)
 #define SNDRV_TIMER_IOCTL_NEXT_DEVICE	_IOWR('T', 0x01, struct snd_timer_id)
 #define SNDRV_TIMER_IOCTL_TREAD_OLD	_IOW('T', 0x02, int)
@@ -990,6 +1006,8 @@  struct snd_timer_status {
 #define SNDRV_TIMER_IOCTL_CONTINUE	_IO('T', 0xa2)
 #define SNDRV_TIMER_IOCTL_PAUSE		_IO('T', 0xa3)
 #define SNDRV_TIMER_IOCTL_TREAD64	_IOW('T', 0xa4, int)
+#define SNDRV_TIMER_IOCTL_CREATE	_IOWR('T', 0xa5, struct snd_utimer_info)
+#define SNDRV_TIMER_IOCTL_TRIGGER	_IO('T', 0xa6)
 
 #if __BITS_PER_LONG == 64
 #define SNDRV_TIMER_IOCTL_TREAD SNDRV_TIMER_IOCTL_TREAD_OLD
diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index b970a1734647..670b26cf3065 100644
--- a/sound/core/Kconfig
+++ b/sound/core/Kconfig
@@ -251,6 +251,16 @@  config SND_JACK_INJECTION_DEBUG
 	  Say Y if you are debugging via jack injection interface.
 	  If unsure select "N".
 
+config SND_UTIMER
+	bool "Enable support for userspace-controlled virtual timers"
+	depends on SND_TIMER
+	help
+	  Say Y to enable the support of userspace-controlled timers. These
+	  timers are purely virtual, and they are supposed to be triggered
+	  from userspace. They could be quite useful when synchronizing the
+	  sound timing with userspace applications (for instance, when sending
+	  data through snd-aloop).
+
 config SND_VMASTER
 	bool
 
diff --git a/sound/core/timer.c b/sound/core/timer.c
index d104adc75a8b..dabb925625f1 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -13,6 +13,9 @@ 
 #include <linux/module.h>
 #include <linux/string.h>
 #include <linux/sched/signal.h>
+#include <linux/anon_inodes.h>
+#include <linux/idr.h>
+#include <linux/units.h>
 #include <sound/core.h>
 #include <sound/timer.h>
 #include <sound/control.h>
@@ -109,6 +112,16 @@  struct snd_timer_status64 {
 	unsigned char reserved[64];	/* reserved */
 };
 
+#ifdef CONFIG_SND_UTIMER
+#define SNDRV_UTIMERS_MAX_COUNT 128
+/* Internal data structure for keeping the state of the userspace-driven timer */
+struct snd_utimer {
+	char *name;
+	struct snd_timer *timer;
+	unsigned int id;
+};
+#endif
+
 #define SNDRV_TIMER_IOCTL_STATUS64	_IOR('T', 0x14, struct snd_timer_status64)
 
 /* list of timers */
@@ -2009,6 +2022,212 @@  enum {
 	SNDRV_TIMER_IOCTL_PAUSE_OLD = _IO('T', 0x23),
 };
 
+#ifdef CONFIG_SND_UTIMER
+/*
+ * Since userspace-driven timers are passed to userspace, we need to have an identifier
+ * which will allow us to use them (basically, the subdevice number of udriven timer).
+ */
+static DEFINE_IDA(snd_utimer_ids);
+
+static void snd_utimer_put_id(struct snd_utimer *utimer)
+{
+	int timer_id = utimer->id;
+
+	snd_BUG_ON(timer_id < 0 || timer_id >= SNDRV_UTIMERS_MAX_COUNT);
+	ida_free(&snd_utimer_ids, timer_id);
+}
+
+static int snd_utimer_take_id(void)
+{
+	return ida_alloc_max(&snd_utimer_ids, SNDRV_UTIMERS_MAX_COUNT - 1, GFP_KERNEL);
+}
+
+static void snd_utimer_free(struct snd_utimer *utimer)
+{
+	snd_timer_free(utimer->timer);
+	snd_utimer_put_id(utimer);
+	kfree(utimer->name);
+	kfree(utimer);
+}
+
+static int snd_utimer_release(struct inode *inode, struct file *file)
+{
+	struct snd_utimer *utimer = (struct snd_utimer *)file->private_data;
+
+	snd_utimer_free(utimer);
+	return 0;
+}
+
+static int snd_utimer_trigger(struct file *file)
+{
+	struct snd_utimer *utimer = (struct snd_utimer *)file->private_data;
+
+	snd_timer_interrupt(utimer->timer, utimer->timer->sticks);
+	return 0;
+}
+
+static long snd_utimer_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
+{
+	switch (ioctl) {
+	case SNDRV_TIMER_IOCTL_TRIGGER:
+		return snd_utimer_trigger(file);
+	}
+
+	return -ENOTTY;
+}
+
+static const struct file_operations snd_utimer_fops = {
+	.llseek = noop_llseek,
+	.release = snd_utimer_release,
+	.unlocked_ioctl = snd_utimer_ioctl,
+};
+
+static int snd_utimer_start(struct snd_timer *t)
+{
+	return 0;
+}
+
+static int snd_utimer_stop(struct snd_timer *t)
+{
+	return 0;
+}
+
+static int snd_utimer_open(struct snd_timer *t)
+{
+	return 0;
+}
+
+static int snd_utimer_close(struct snd_timer *t)
+{
+	return 0;
+}
+
+static const struct snd_timer_hardware timer_hw = {
+	.flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_WORK,
+	.open = snd_utimer_open,
+	.close = snd_utimer_close,
+	.start = snd_utimer_start,
+	.stop = snd_utimer_stop,
+};
+
+static int snd_utimer_create(struct snd_utimer_info *utimer_info,
+			     struct snd_utimer **r_utimer)
+{
+	struct snd_utimer *utimer;
+	struct snd_timer *timer;
+	struct snd_timer_id tid;
+	int utimer_id;
+	int err = 0;
+	u64 resolution;
+
+	if (!utimer_info || utimer_info->frame_rate == 0 || utimer_info->period_size == 0)
+		return -EINVAL;
+
+	/* Let's check that we won't get an overflow in the resolution */
+	if (NANO / utimer_info->frame_rate > U64_MAX / utimer_info->period_size)
+		return -EINVAL;
+
+	resolution = NANO / utimer_info->frame_rate * utimer_info->period_size;
+
+	if (resolution == 0)
+		return -EINVAL;
+
+	utimer = kzalloc(sizeof(*utimer), GFP_KERNEL);
+	if (!utimer)
+		return -ENOMEM;
+
+	/* We hold the ioctl lock here so we won't get a race condition when allocating id */
+	utimer_id = snd_utimer_take_id();
+	if (utimer_id < 0) {
+		err = utimer_id;
+		goto err_take_id;
+	}
+
+	utimer->name = kasprintf(GFP_KERNEL, "snd-utimer%d", utimer_id);
+	if (!utimer->name) {
+		err = -ENOMEM;
+		goto err_get_name;
+	}
+
+	utimer->id = utimer_id;
+
+	tid.dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION;
+	tid.dev_class = SNDRV_TIMER_CLASS_GLOBAL;
+	tid.card = -1;
+	tid.device = SNDRV_TIMER_GLOBAL_UDRIVEN;
+	tid.subdevice = utimer_id;
+
+	err = snd_timer_new(NULL, utimer->name, &tid, &timer);
+	if (err < 0) {
+		pr_err("Can't create userspace-driven timer\n");
+		goto err_timer_new;
+	}
+
+	timer->module = THIS_MODULE;
+	timer->hw = timer_hw;
+	timer->hw.resolution = resolution;
+	timer->hw.ticks = 1;
+	timer->max_instances = MAX_SLAVE_INSTANCES;
+
+	utimer->timer = timer;
+
+	err = snd_timer_global_register(timer);
+	if (err < 0) {
+		pr_err("Can't register a userspace-driven timer\n");
+		goto err_timer_reg;
+	}
+
+	*r_utimer = utimer;
+	return 0;
+
+err_timer_reg:
+	snd_timer_free(timer);
+err_timer_new:
+	kfree(utimer->name);
+err_get_name:
+	snd_utimer_put_id(utimer);
+err_take_id:
+	kfree(utimer);
+
+	return err;
+}
+
+static int snd_utimer_ioctl_create(struct file *file,
+				   struct snd_utimer_info __user *_utimer_info)
+{
+	struct snd_utimer *utimer;
+	struct snd_utimer_info *utimer_info __free(kfree) = NULL;
+	int err;
+
+	utimer_info = memdup_user(_utimer_info, sizeof(*utimer_info));
+	if (IS_ERR(utimer_info))
+		return PTR_ERR(no_free_ptr(utimer_info));
+
+	err = snd_utimer_create(utimer_info, &utimer);
+	if (err < 0)
+		return err;
+
+	utimer_info->id = utimer->id;
+
+	err = copy_to_user(_utimer_info, utimer_info, sizeof(*utimer_info));
+	if (err) {
+		snd_utimer_free(utimer);
+		return -EFAULT;
+	}
+
+	return anon_inode_getfd(utimer->name, &snd_utimer_fops, utimer, O_RDWR | O_CLOEXEC);
+}
+
+#else
+
+static int snd_utimer_ioctl_create(struct file *file,
+				   struct snd_utimer_info __user *_utimer_info)
+{
+	return -ENOTTY;
+}
+
+#endif
+
 static long __snd_timer_user_ioctl(struct file *file, unsigned int cmd,
 				 unsigned long arg, bool compat)
 {
@@ -2053,6 +2272,8 @@  static long __snd_timer_user_ioctl(struct file *file, unsigned int cmd,
 	case SNDRV_TIMER_IOCTL_PAUSE:
 	case SNDRV_TIMER_IOCTL_PAUSE_OLD:
 		return snd_timer_user_pause(file);
+	case SNDRV_TIMER_IOCTL_CREATE:
+		return snd_utimer_ioctl_create(file, argp);
 	}
 	return -ENOTTY;
 }