diff options
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/core/Kconfig | 10 | ||||
| -rw-r--r-- | sound/core/timer.c | 225 |
2 files changed, 235 insertions, 0 deletions
diff --git a/sound/core/Kconfig b/sound/core/Kconfig index f0ba87d4e504..2c5b9f964703 100644 --- a/sound/core/Kconfig +++ b/sound/core/Kconfig @@ -242,6 +242,16 @@ 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 71a07c1662f5..7610f102360d 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -13,6 +13,8 @@ #include <linux/module.h> #include <linux/string.h> #include <linux/sched/signal.h> +#include <linux/anon_inodes.h> +#include <linux/idr.h> #include <sound/core.h> #include <sound/timer.h> #include <sound/control.h> @@ -109,6 +111,16 @@ 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 +2021,217 @@ 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_timer_uinfo *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; + + if (!utimer_info || utimer_info->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 = utimer_info->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_timer_uinfo __user *_utimer_info) +{ + struct snd_utimer *utimer; + struct snd_timer_uinfo *utimer_info __free(kfree) = NULL; + int err, timer_fd; + + 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; + + timer_fd = anon_inode_getfd(utimer->name, &snd_utimer_fops, utimer, O_RDWR | O_CLOEXEC); + if (timer_fd < 0) { + snd_utimer_free(utimer); + return timer_fd; + } + + utimer_info->fd = timer_fd; + + err = copy_to_user(_utimer_info, utimer_info, sizeof(*utimer_info)); + if (err) { + /* + * "Leak" the fd, as there is nothing we can do about it. + * It might have been closed already since anon_inode_getfd + * makes it available for userspace. + * + * We have to rely on the process exit path to do any + * necessary cleanup (e.g. releasing the file). + */ + return -EFAULT; + } + + return 0; +} + +#else + +static int snd_utimer_ioctl_create(struct file *file, + struct snd_timer_uinfo __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 +2276,8 @@ 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; } |