ALSA: ctxfi - Use native timer interrupt on emu20k1

emu20k1 has a native timer interrupt based on the audio clock, which
is more accurate than the system timer (from the synchronization POV).
This patch adds the code to handle this with multiple streams.

The system timer is still used on emu20k2, and can be used also for
emu20k1 easily by changing USE_SYSTEM_TIMER to 1 in cttimer.c.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 417 insertions, 0 deletions

diff --git a/sound/pci/ctxfi/cttimer.c b/sound/pci/ctxfi/cttimer.c
new file mode 100644
index 000000000000..3acb26d0c4cc
--- /dev/null
+++ b/sound/pci/ctxfi/cttimer.c
@@ -0,0 +1,417 @@
+/*
+ * PCM timer handling on ctxfi
+ *
+ * This source file is released under GPL v2 license (no other versions).
+ * See the COPYING file included in the main directory of this source
+ * distribution for the license terms and conditions.
+ */
+
+#include <linux/slab.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include "ctatc.h"
+#include "cthardware.h"
+#include "cttimer.h"
+
+struct ct_timer_ops {
+        void (*init)(struct ct_timer_instance *);
+        void (*prepare)(struct ct_timer_instance *);
+        void (*start)(struct ct_timer_instance *);
+        void (*stop)(struct ct_timer_instance *);
+        void (*free_instance)(struct ct_timer_instance *);
+        void (*interrupt)(struct ct_timer *);
+        void (*free_global)(struct ct_timer *);
+};
+
+/* timer instance -- assigned to each PCM stream */
+struct ct_timer_instance {
+        spinlock_t lock;
+        struct ct_timer *timer_base;
+        struct ct_atc_pcm *apcm;
+        struct snd_pcm_substream *substream;
+        struct timer_list timer;
+        struct list_head instance_list;
+        struct list_head running_list;
+        unsigned int position;
+        unsigned int frag_count;
+        unsigned int running:1;
+        unsigned int need_update:1;
+};
+
+/* timer instance manager */
+struct ct_timer {
+        spinlock_t lock;                /* global timer lock (for xfitimer) */
+        spinlock_t list_lock;           /* lock for instance list */
+        struct ct_atc *atc;
+        struct ct_timer_ops *ops;
+        struct list_head instance_head;
+        struct list_head running_head;
+        unsigned int irq_handling:1;    /* in IRQ handling */
+        unsigned int reprogram:1;       /* need to reprogram the internval */
+        unsigned int running:1;         /* global timer running */
+};
+
+
+/*
+ * system-timer-based updates
+ */
+
+static void ct_systimer_callback(unsigned long data)
+{
+        struct ct_timer_instance *ti = (struct ct_timer_instance *)data;
+        struct snd_pcm_substream *substream = ti->substream;
+        struct snd_pcm_runtime *runtime = substream->runtime;
+        struct ct_atc_pcm *apcm = ti->apcm;
+        unsigned int period_size = runtime->period_size;
+        unsigned int buffer_size = runtime->buffer_size;
+        unsigned long flags;
+        unsigned int position, dist, interval;
+
+        position = substream->ops->pointer(substream);
+        dist = (position + buffer_size - ti->position) % buffer_size;
+        if (dist >= period_size ||
+            position / period_size != ti->position / period_size) {
+                apcm->interrupt(apcm);
+                ti->position = position;
+        }
+        /* Add extra HZ*5/1000 to avoid overrun issue when recording
+         * at 8kHz in 8-bit format or at 88kHz in 24-bit format. */
+        interval = ((period_size - (position % period_size))
+                   * HZ + (runtime->rate - 1)) / runtime->rate + HZ * 5 / 1000;
+        spin_lock_irqsave(&ti->lock, flags);
+        if (ti->running)
+                mod_timer(&ti->timer, jiffies + interval);
+        spin_unlock_irqrestore(&ti->lock, flags);
+}
+
+static void ct_systimer_init(struct ct_timer_instance *ti)
+{
+        setup_timer(&ti->timer, ct_systimer_callback,
+                    (unsigned long)ti);
+}
+
+static void ct_systimer_start(struct ct_timer_instance *ti)
+{
+        struct snd_pcm_runtime *runtime = ti->substream->runtime;
+        unsigned long flags;
+
+        spin_lock_irqsave(&ti->lock, flags);
+        ti->running = 1;
+        mod_timer(&ti->timer,
+                  jiffies + (runtime->period_size * HZ +
+                             (runtime->rate - 1)) / runtime->rate);
+        spin_unlock_irqrestore(&ti->lock, flags);
+}
+
+static void ct_systimer_stop(struct ct_timer_instance *ti)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&ti->lock, flags);
+        ti->running = 0;
+        del_timer(&ti->timer);
+        spin_unlock_irqrestore(&ti->lock, flags);
+}
+
+static void ct_systimer_prepare(struct ct_timer_instance *ti)
+{
+        ct_systimer_stop(ti);
+        try_to_del_timer_sync(&ti->timer);
+}
+
+#define ct_systimer_free        ct_systimer_prepare
+
+static struct ct_timer_ops ct_systimer_ops = {
+        .init = ct_systimer_init,
+        .free_instance = ct_systimer_free,
+        .prepare = ct_systimer_prepare,
+        .start = ct_systimer_start,
+        .stop = ct_systimer_stop,
+};
+
+
+/*
+ * Handling multiple streams using a global emu20k1 timer irq
+ */
+
+#define CT_TIMER_FREQ   48000
+#define MAX_TICKS       ((1 << 13) - 1)
+
+static void ct_xfitimer_irq_rearm(struct ct_timer *atimer, int ticks)
+{
+        struct hw *hw = atimer->atc->hw;
+        if (ticks > MAX_TICKS)
+                ticks = MAX_TICKS;
+        hw->set_timer_tick(hw, ticks);
+        if (!atimer->running)
+                hw->set_timer_irq(hw, 1);
+        atimer->running = 1;
+}
+
+static void ct_xfitimer_irq_stop(struct ct_timer *atimer)
+{
+        if (atimer->running) {
+                struct hw *hw = atimer->atc->hw;
+                hw->set_timer_irq(hw, 0);
+                hw->set_timer_tick(hw, 0);
+                atimer->running = 0;
+        }
+}
+
+/*
+ * reprogram the timer interval;
+ * checks the running instance list and determines the next timer interval.
+ * also updates the each stream position, returns the number of streams
+ * to call snd_pcm_period_elapsed() appropriately
+ *
+ * call this inside the lock and irq disabled
+ */
+static int ct_xfitimer_reprogram(struct ct_timer *atimer)
+{
+        struct ct_timer_instance *ti;
+        int min_intr = -1;
+        int updates = 0;
+
+        list_for_each_entry(ti, &atimer->running_head, running_list) {
+                struct snd_pcm_runtime *runtime;
+                unsigned int pos, diff;
+                int intr;
+                runtime = ti->substream->runtime;
+                pos = ti->substream->ops->pointer(ti->substream);
+                if (pos < ti->position)
+                        diff = runtime->buffer_size - ti->position + pos;
+                else
+                        diff = pos - ti->position;
+                ti->position = pos;
+                while (diff >= ti->frag_count) {
+                        ti->frag_count += runtime->period_size;
+                        ti->need_update = 1;
+                        updates++;
+                }
+                ti->frag_count -= diff;
+                intr = div_u64((u64)ti->frag_count * CT_TIMER_FREQ,
+                               runtime->rate);
+                if (min_intr < 0 || intr < min_intr)
+                        min_intr = intr;
+        }
+
+        if (min_intr > 0)
+                ct_xfitimer_irq_rearm(atimer, min_intr);
+        else
+                ct_xfitimer_irq_stop(atimer);
+
+        atimer->reprogram = 0; /* clear flag */
+        return updates;
+}
+
+/* look through the instance list and call period_elapsed if needed */
+static void ct_xfitimer_check_period(struct ct_timer *atimer)
+{
+        struct ct_timer_instance *ti;
+        unsigned long flags;
+
+        spin_lock_irqsave(&atimer->list_lock, flags);
+        list_for_each_entry(ti, &atimer->instance_head, instance_list) {
+                if (ti->need_update) {
+                        ti->need_update = 0;
+                        ti->apcm->interrupt(ti->apcm);
+                }
+        }
+        spin_unlock_irqrestore(&atimer->list_lock, flags);
+}
+
+/* Handle timer-interrupt */
+static void ct_xfitimer_callback(struct ct_timer *atimer)
+{
+        int update;
+        unsigned long flags;
+
+        spin_lock_irqsave(&atimer->lock, flags);
+        atimer->irq_handling = 1;
+        do {
+                update = ct_xfitimer_reprogram(atimer);
+                spin_unlock(&atimer->lock);
+                if (update)
+                        ct_xfitimer_check_period(atimer);
+                spin_lock(&atimer->lock);
+        } while (atimer->reprogram);
+        atimer->irq_handling = 0;
+        spin_unlock_irqrestore(&atimer->lock, flags);
+}
+
+static void ct_xfitimer_prepare(struct ct_timer_instance *ti)
+{
+        ti->frag_count = ti->substream->runtime->period_size;
+        ti->need_update = 0;
+}
+
+
+/* start/stop the timer */
+static void ct_xfitimer_update(struct ct_timer *atimer)
+{
+        unsigned long flags;
+        int update;
+
+        if (atimer->irq_handling) {
+                /* reached from IRQ handler; let it handle later */
+                atimer->reprogram = 1;
+                return;
+        }
+
+        spin_lock_irqsave(&atimer->lock, flags);
+        ct_xfitimer_irq_stop(atimer);
+        update = ct_xfitimer_reprogram(atimer);
+        spin_unlock_irqrestore(&atimer->lock, flags);
+        if (update)
+                ct_xfitimer_check_period(atimer);
+}
+
+static void ct_xfitimer_start(struct ct_timer_instance *ti)
+{
+        struct ct_timer *atimer = ti->timer_base;
+        unsigned long flags;
+
+        spin_lock_irqsave(&atimer->lock, flags);
+        list_add(&ti->running_list, &atimer->running_head);
+        spin_unlock_irqrestore(&atimer->lock, flags);
+        ct_xfitimer_update(atimer);
+}
+
+static void ct_xfitimer_stop(struct ct_timer_instance *ti)
+{
+        struct ct_timer *atimer = ti->timer_base;
+        unsigned long flags;
+
+        spin_lock_irqsave(&atimer->lock, flags);
+        list_del_init(&ti->running_list);
+        ti->need_update = 0;
+        spin_unlock_irqrestore(&atimer->lock, flags);
+        ct_xfitimer_update(atimer);
+}
+
+static void ct_xfitimer_free_global(struct ct_timer *atimer)
+{
+        ct_xfitimer_irq_stop(atimer);
+}
+
+static struct ct_timer_ops ct_xfitimer_ops = {
+        .prepare = ct_xfitimer_prepare,
+        .start = ct_xfitimer_start,
+        .stop = ct_xfitimer_stop,
+        .interrupt = ct_xfitimer_callback,
+        .free_global = ct_xfitimer_free_global,
+};
+
+/*
+ * timer instance
+ */
+
+struct ct_timer_instance *
+ct_timer_instance_new(struct ct_timer *atimer, struct ct_atc_pcm *apcm)
+{
+        struct ct_timer_instance *ti;
+
+        ti = kzalloc(sizeof(*ti), GFP_KERNEL);
+        if (!ti)
+                return NULL;
+        spin_lock_init(&ti->lock);
+        INIT_LIST_HEAD(&ti->instance_list);
+        INIT_LIST_HEAD(&ti->running_list);
+        ti->timer_base = atimer;
+        ti->apcm = apcm;
+        ti->substream = apcm->substream;
+        if (atimer->ops->init)
+                atimer->ops->init(ti);
+
+        spin_lock_irq(&atimer->list_lock);
+        list_add(&ti->instance_list, &atimer->instance_head);
+        spin_unlock_irq(&atimer->list_lock);
+
+        return ti;
+}
+
+void ct_timer_prepare(struct ct_timer_instance *ti)
+{
+        if (ti->timer_base->ops->prepare)
+                ti->timer_base->ops->prepare(ti);
+        ti->position = 0;
+        ti->running = 0;
+}
+
+void ct_timer_start(struct ct_timer_instance *ti)
+{
+        struct ct_timer *atimer = ti->timer_base;
+        atimer->ops->start(ti);
+}
+
+void ct_timer_stop(struct ct_timer_instance *ti)
+{
+        struct ct_timer *atimer = ti->timer_base;
+        atimer->ops->stop(ti);
+}
+
+void ct_timer_instance_free(struct ct_timer_instance *ti)
+{
+        struct ct_timer *atimer = ti->timer_base;
+
+        atimer->ops->stop(ti); /* to be sure */
+        if (atimer->ops->free_instance)
+                atimer->ops->free_instance(ti);
+
+        spin_lock_irq(&atimer->list_lock);
+        list_del(&ti->instance_list);
+        spin_unlock_irq(&atimer->list_lock);
+
+        kfree(ti);
+}
+
+/*
+ * timer manager
+ */
+
+#define USE_SYSTEM_TIMER        0
+
+static void ct_timer_interrupt(void *data, unsigned int status)
+{
+        struct ct_timer *timer = data;
+
+        /* Interval timer interrupt */
+        if ((status & IT_INT) && timer->ops->interrupt)
+                timer->ops->interrupt(timer);
+}
+
+struct ct_timer *ct_timer_new(struct ct_atc *atc)
+{
+        struct ct_timer *atimer;
+        struct hw *hw;
+
+        atimer = kzalloc(sizeof(*atimer), GFP_KERNEL);
+        if (!atimer)
+                return NULL;
+        spin_lock_init(&atimer->lock);
+        spin_lock_init(&atimer->list_lock);
+        INIT_LIST_HEAD(&atimer->instance_head);
+        INIT_LIST_HEAD(&atimer->running_head);
+        atimer->atc = atc;
+        hw = atc->hw;
+        if (!USE_SYSTEM_TIMER && hw->set_timer_irq) {
+                printk(KERN_INFO "ctxfi: Use xfi-native timer\n");
+                atimer->ops = &ct_xfitimer_ops;
+                hw->irq_callback_data = atimer;
+                hw->irq_callback = ct_timer_interrupt;
+        } else {
+                printk(KERN_INFO "ctxfi: Use system timer\n");
+                atimer->ops = &ct_systimer_ops;
+        }
+        return atimer;
+}
+
+void ct_timer_free(struct ct_timer *atimer)
+{
+        struct hw *hw = atimer->atc->hw;
+        hw->irq_callback = NULL;
+        if (atimer->ops->free_global)
+                atimer->ops->free_global(atimer);
+        kfree(atimer);
+}
+