ALSA: dice: implement hwdep device

Implement the hwdep locking and notification mechanisms.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

1 files changed, 203 insertions, 22 deletions

diff --git a/sound/firewire/dice.c b/sound/firewire/dice.c
index d0575a96ea70..7225878a09cc 100644
--- a/sound/firewire/dice.c
+++ b/sound/firewire/dice.c
@@ -5,6 +5,7 @@
  * Licensed under the terms of the GNU General Public License, version 2.
  */
 
+#include <linux/compat.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/firewire.h>
@@ -13,8 +14,11 @@
 #include <linux/mod_devicetable.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
 #include <sound/control.h>
 #include <sound/core.h>
+#include <sound/firewire.h>
 #include <sound/hwdep.h>
 #include <sound/initval.h>
 #include <sound/pcm.h>
@@ -233,13 +237,18 @@
 struct dice {
         struct snd_card *card;
         struct fw_unit *unit;
+        spinlock_t lock;
         struct mutex mutex;
         unsigned int global_offset;
         unsigned int rx_offset;
         struct fw_address_handler notification_handler;
         int owner_generation;
+        int dev_lock_count; /* > 0 driver, < 0 userspace */
+        bool dev_lock_changed;
         bool global_enabled;
         bool stream_running;
+        wait_queue_head_t hwdep_wait;
+        u32 notification_bits;
         struct snd_pcm_substream *pcm;
         struct fw_iso_resources resources;
         struct amdtp_out_stream stream;
@@ -259,6 +268,47 @@ static const unsigned int dice_rates[] = {
         [6] = 192000,
 };
 
+static void dice_lock_changed(struct dice *dice)
+{
+        dice->dev_lock_changed = true;
+        wake_up(&dice->hwdep_wait);
+}
+
+static int dice_try_lock(struct dice *dice)
+{
+        int err;
+
+        spin_lock_irq(&dice->lock);
+
+        if (dice->dev_lock_count < 0) {
+                err = -EBUSY;
+                goto out;
+        }
+
+        if (dice->dev_lock_count++ == 0)
+                dice_lock_changed(dice);
+        err = 0;
+
+out:
+        spin_unlock_irq(&dice->lock);
+
+        return err;
+}
+
+static void dice_unlock(struct dice *dice)
+{
+        spin_lock_irq(&dice->lock);
+
+        if (WARN_ON(dice->dev_lock_count <= 0))
+                goto out;
+
+        if (--dice->dev_lock_count == 0)
+                dice_lock_changed(dice);
+
+out:
+        spin_unlock_irq(&dice->lock);
+}
+
 static inline u64 global_address(struct dice *dice, unsigned int offset)
 {
         return DICE_PRIVATE_SPACE + dice->global_offset + offset;
@@ -496,6 +546,7 @@ static void dice_notification(struct fw_card *card, struct fw_request *request,
                               void *data, size_t length, void *callback_data)
 {
         struct dice *dice = callback_data;
+        unsigned long flags;
 
         if (tcode != TCODE_WRITE_QUADLET_REQUEST) {
                 fw_send_response(card, request, RCODE_TYPE_ERROR);
@@ -505,9 +556,11 @@ static void dice_notification(struct fw_card *card, struct fw_request *request,
                 fw_send_response(card, request, RCODE_ADDRESS_ERROR);
                 return;
         }
-        dev_dbg(&dice->unit->device,
-                "notification: %08x\n", be32_to_cpup(data));
+        spin_lock_irqsave(&dice->lock, flags);
+        dice->notification_bits |= be32_to_cpup(data);
+        spin_unlock_irqrestore(&dice->lock, flags);
         fw_send_response(card, request, RCODE_COMPLETE);
+        wake_up(&dice->hwdep_wait);
 }
 
 static int dice_open(struct snd_pcm_substream *substream)
@@ -531,26 +584,32 @@ static int dice_open(struct snd_pcm_substream *substream)
         unsigned int rate;
         int err;
 
+        err = dice_try_lock(dice);
+        if (err < 0)
+                goto error;
+
         err = snd_fw_transaction(dice->unit, TCODE_READ_QUADLET_REQUEST,
                                  global_address(dice, GLOBAL_CLOCK_SELECT),
                                  &clock_sel, 4);
         if (err < 0)
-                return err;
+                goto err_lock;
         rate = (be32_to_cpu(clock_sel) & CLOCK_RATE_MASK) >> CLOCK_RATE_SHIFT;
-        if (rate >= ARRAY_SIZE(dice_rates))
-                return -ENXIO;
+        if (rate >= ARRAY_SIZE(dice_rates)) {
+                err = -ENXIO;
+                goto err_lock;
+        }
         rate = dice_rates[rate];
 
         err = snd_fw_transaction(dice->unit, TCODE_READ_QUADLET_REQUEST,
                                  rx_address(dice, RX_NUMBER_AUDIO),
                                  &number_audio, 4);
         if (err < 0)
-                return err;
+                goto err_lock;
         err = snd_fw_transaction(dice->unit, TCODE_READ_QUADLET_REQUEST,
                                  rx_address(dice, RX_NUMBER_MIDI),
                                  &number_midi, 4);
         if (err < 0)
-                return err;
+                goto err_lock;
 
         runtime->hw = hardware;
 
@@ -568,17 +627,26 @@ static int dice_open(struct snd_pcm_substream *substream)
                                            SNDRV_PCM_HW_PARAM_PERIOD_TIME,
                                            5000, 8192000);
         if (err < 0)
-                return err;
+                goto err_lock;
 
         err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
         if (err < 0)
-                return err;
+                goto err_lock;
 
         return 0;
+
+err_lock:
+        dice_unlock(dice);
+error:
+        return err;
 }
 
 static int dice_close(struct snd_pcm_substream *substream)
 {
+        struct dice *dice = substream->private_data;
+
+        dice_unlock(dice);
+
         return 0;
 }
 
@@ -783,45 +851,156 @@ static int dice_create_pcm(struct dice *dice)
         return 0;
 }
 
-// TODO: implement these
-
 static long dice_hwdep_read(struct snd_hwdep *hwdep, char __user *buf,
                             long count, loff_t *offset)
 {
-        return -EIO;
+        struct dice *dice = hwdep->private_data;
+        DEFINE_WAIT(wait);
+        union snd_firewire_event event;
+
+        spin_lock_irq(&dice->lock);
+
+        while (!dice->dev_lock_changed && dice->notification_bits == 0) {
+                prepare_to_wait(&dice->hwdep_wait, &wait, TASK_INTERRUPTIBLE);
+                spin_unlock_irq(&dice->lock);
+                schedule();
+                finish_wait(&dice->hwdep_wait, &wait);
+                if (signal_pending(current))
+                        return -ERESTARTSYS;
+                spin_lock_irq(&dice->lock);
+        }
+
+        memset(&event, 0, sizeof(event));
+        if (dice->dev_lock_changed) {
+                event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS;
+                event.lock_status.status = dice->dev_lock_count > 0;
+                dice->dev_lock_changed = false;
+
+                count = min(count, (long)sizeof(event.lock_status));
+        } else {
+                event.dice_notification.type = SNDRV_FIREWIRE_EVENT_DICE_NOTIFICATION;
+                event.dice_notification.notification = dice->notification_bits;
+                dice->notification_bits = 0;
+
+                count = min(count, (long)sizeof(event.dice_notification));
+        }
+
+        spin_unlock_irq(&dice->lock);
+
+        if (copy_to_user(buf, &event, count))
+                return -EFAULT;
+
+        return count;
 }
 
-static int dice_hwdep_open(struct snd_hwdep *hwdep, struct file *file)
+static unsigned int dice_hwdep_poll(struct snd_hwdep *hwdep, struct file *file,
+                                    poll_table *wait)
 {
-        return -EIO;
+        struct dice *dice = hwdep->private_data;
+        unsigned int events;
+
+        poll_wait(file, &dice->hwdep_wait, wait);
+
+        spin_lock_irq(&dice->lock);
+        if (dice->dev_lock_changed || dice->notification_bits != 0)
+                events = POLLIN | POLLRDNORM;
+        else
+                events = 0;
+        spin_unlock_irq(&dice->lock);
+
+        return events;
 }
 
-static int dice_hwdep_release(struct snd_hwdep *hwdep, struct file *file)
+static int dice_hwdep_get_info(struct dice *dice, void __user *arg)
 {
+        struct fw_device *dev = fw_parent_device(dice->unit);
+        struct snd_firewire_get_info info;
+
+        memset(&info, 0, sizeof(info));
+        info.type = SNDRV_FIREWIRE_TYPE_DICE;
+        info.card = dev->card->index;
+        *(__be32 *)&info.guid[0] = cpu_to_be32(dev->config_rom[3]);
+        *(__be32 *)&info.guid[4] = cpu_to_be32(dev->config_rom[4]);
+        strlcpy(info.device_name, dev_name(&dev->device),
+                sizeof(info.device_name));
+
+        if (copy_to_user(arg, &info, sizeof(info)))
+                return -EFAULT;
+
         return 0;
 }
 
-static unsigned int dice_hwdep_poll(struct snd_hwdep *hwdep, struct file *file,
-                                    poll_table *wait)
+static int dice_hwdep_lock(struct dice *dice)
+{
+        int err;
+
+        spin_lock_irq(&dice->lock);
+
+        if (dice->dev_lock_count == 0) {
+                dice->dev_lock_count = -1;
+                err = 0;
+        } else {
+                err = -EBUSY;
+        }
+
+        spin_unlock_irq(&dice->lock);
+
+        return err;
+}
+
+static int dice_hwdep_unlock(struct dice *dice)
 {
-        return POLLERR | POLLHUP;
+        int err;
+
+        spin_lock_irq(&dice->lock);
+
+        if (dice->dev_lock_count == -1) {
+                dice->dev_lock_count = 0;
+                err = 0;
+        } else {
+                err = -EBADFD;
+        }
+
+        spin_unlock_irq(&dice->lock);
+
+        return err;
 }
 
 static int dice_hwdep_ioctl(struct snd_hwdep *hwdep, struct file *file,
                             unsigned int cmd, unsigned long arg)
 {
-        return -EIO;
+        struct dice *dice = hwdep->private_data;
+
+        switch (cmd) {
+        case SNDRV_FIREWIRE_IOCTL_GET_INFO:
+                return dice_hwdep_get_info(dice, (void __user *)arg);
+        case SNDRV_FIREWIRE_IOCTL_LOCK:
+                return dice_hwdep_lock(dice);
+        case SNDRV_FIREWIRE_IOCTL_UNLOCK:
+                return dice_hwdep_unlock(dice);
+        default:
+                return -ENOIOCTLCMD;
+        }
+}
+
+#ifdef CONFIG_COMPAT
+static int dice_hwdep_compat_ioctl(struct snd_hwdep *hwdep, struct file *file,
+                                   unsigned int cmd, unsigned long arg)
+{
+        return dice_hwdep_ioctl(hwdep, file, cmd,
+                                (unsigned long)compat_ptr(arg));
 }
+#else
+#define dice_hwdep_compat_ioctl NULL
+#endif
 
 static int dice_create_hwdep(struct dice *dice)
 {
         static const struct snd_hwdep_ops ops = {
                 .read         = dice_hwdep_read,
-                .open         = dice_hwdep_open,
-                .release      = dice_hwdep_release,
                 .poll         = dice_hwdep_poll,
                 .ioctl        = dice_hwdep_ioctl,
-                .ioctl_compat = dice_hwdep_ioctl,
+                .ioctl_compat = dice_hwdep_compat_ioctl,
         };
         struct snd_hwdep *hwdep;
         int err;
@@ -922,8 +1101,10 @@ static int dice_probe(struct fw_unit *unit, const struct ieee1394_device_id *id)
 
         dice = card->private_data;
         dice->card = card;
+        spin_lock_init(&dice->lock);
         mutex_init(&dice->mutex);
         dice->unit = unit;
+        init_waitqueue_head(&dice->hwdep_wait);
 
         err = dice_init_offsets(dice);
         if (err < 0)