ALSA - hda: Add support for link audio time reporting
authorGuneshwor Singh <guneshwor.o.singh@intel.com>
Thu, 4 Aug 2016 10:16:04 +0000 (15:46 +0530)
committerTakashi Iwai <tiwai@suse.de>
Tue, 9 Aug 2016 06:53:56 +0000 (08:53 +0200)
The HDA controller from SKL onwards support additional timestamp
reporting of the link time. The link time is read from HW
registers and converted to audio values.

Signed-off-by: Guneshwor Singh <guneshwor.o.singh@intel.com>
Signed-off-by: Hardik T Shah <hardik.t.shah@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
sound/pci/hda/hda_controller.c

index 1567fe209e01e733346636c894f7f57238c113a5..2ad3b447483f0fb97cae1f401ef7cf5e02068644 100644 (file)
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
+
+#ifdef CONFIG_X86
+/* for art-tsc conversion */
+#include <asm/tsc.h>
+#endif
+
 #include <sound/core.h>
 #include <sound/initval.h>
 #include "hda_controller.h"
@@ -337,12 +343,173 @@ static snd_pcm_uframes_t azx_pcm_pointer(struct snd_pcm_substream *substream)
                               azx_get_position(chip, azx_dev));
 }
 
+/*
+ * azx_scale64: Scale base by mult/div while not overflowing sanely
+ *
+ * Derived from scale64_check_overflow in kernel/time/timekeeping.c
+ *
+ * The tmestamps for a 48Khz stream can overflow after (2^64/10^9)/48K which
+ * is about 384307 ie ~4.5 days.
+ *
+ * This scales the calculation so that overflow will happen but after 2^64 /
+ * 48000 secs, which is pretty large!
+ *
+ * In caln below:
+ *     base may overflow, but since there isn’t any additional division
+ *     performed on base it’s OK
+ *     rem can’t overflow because both are 32-bit values
+ */
+
+#ifdef CONFIG_X86
+static u64 azx_scale64(u64 base, u32 num, u32 den)
+{
+       u64 rem;
+
+       rem = do_div(base, den);
+
+       base *= num;
+       rem *= num;
+
+       do_div(rem, den);
+
+       return base + rem;
+}
+
+static int azx_get_sync_time(ktime_t *device,
+               struct system_counterval_t *system, void *ctx)
+{
+       struct snd_pcm_substream *substream = ctx;
+       struct azx_dev *azx_dev = get_azx_dev(substream);
+       struct azx_pcm *apcm = snd_pcm_substream_chip(substream);
+       struct azx *chip = apcm->chip;
+       struct snd_pcm_runtime *runtime;
+       u64 ll_counter, ll_counter_l, ll_counter_h;
+       u64 tsc_counter, tsc_counter_l, tsc_counter_h;
+       u32 wallclk_ctr, wallclk_cycles;
+       bool direction;
+       u32 dma_select;
+       u32 timeout = 200;
+       u32 retry_count = 0;
+
+       runtime = substream->runtime;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               direction = 1;
+       else
+               direction = 0;
+
+       /* 0th stream tag is not used, so DMA ch 0 is for 1st stream tag */
+       do {
+               timeout = 100;
+               dma_select = (direction << GTSCC_CDMAS_DMA_DIR_SHIFT) |
+                                       (azx_dev->core.stream_tag - 1);
+               snd_hdac_chip_writel(azx_bus(chip), GTSCC, dma_select);
+
+               /* Enable the capture */
+               snd_hdac_chip_updatel(azx_bus(chip), GTSCC, 0, GTSCC_TSCCI_MASK);
+
+               while (timeout) {
+                       if (snd_hdac_chip_readl(azx_bus(chip), GTSCC) &
+                                               GTSCC_TSCCD_MASK)
+                               break;
+
+                       timeout--;
+               }
+
+               if (!timeout) {
+                       dev_err(chip->card->dev, "GTSCC capture Timedout!\n");
+                       return -EIO;
+               }
+
+               /* Read wall clock counter */
+               wallclk_ctr = snd_hdac_chip_readl(azx_bus(chip), WALFCC);
+
+               /* Read TSC counter */
+               tsc_counter_l = snd_hdac_chip_readl(azx_bus(chip), TSCCL);
+               tsc_counter_h = snd_hdac_chip_readl(azx_bus(chip), TSCCU);
+
+               /* Read Link counter */
+               ll_counter_l = snd_hdac_chip_readl(azx_bus(chip), LLPCL);
+               ll_counter_h = snd_hdac_chip_readl(azx_bus(chip), LLPCU);
+
+               /* Ack: registers read done */
+               snd_hdac_chip_writel(azx_bus(chip), GTSCC, GTSCC_TSCCD_SHIFT);
+
+               tsc_counter = (tsc_counter_h << TSCCU_CCU_SHIFT) |
+                                               tsc_counter_l;
+
+               ll_counter = (ll_counter_h << LLPC_CCU_SHIFT) | ll_counter_l;
+               wallclk_cycles = wallclk_ctr & WALFCC_CIF_MASK;
+
+               /*
+                * An error occurs near frame "rollover". The clocks in
+                * frame value indicates whether this error may have
+                * occurred. Here we use the value of 10 i.e.,
+                * HDA_MAX_CYCLE_OFFSET
+                */
+               if (wallclk_cycles < HDA_MAX_CYCLE_VALUE - HDA_MAX_CYCLE_OFFSET
+                                       && wallclk_cycles > HDA_MAX_CYCLE_OFFSET)
+                       break;
+
+               /*
+                * Sleep before we read again, else we may again get
+                * value near to MAX_CYCLE. Try to sleep for different
+                * amount of time so we dont hit the same number again
+                */
+               udelay(retry_count++);
+
+       } while (retry_count != HDA_MAX_CYCLE_READ_RETRY);
+
+       if (retry_count == HDA_MAX_CYCLE_READ_RETRY) {
+               dev_err_ratelimited(chip->card->dev,
+                       "Error in WALFCC cycle count\n");
+               return -EIO;
+       }
+
+       *device = ns_to_ktime(azx_scale64(ll_counter,
+                               NSEC_PER_SEC, runtime->rate));
+       *device = ktime_add_ns(*device, (wallclk_cycles * NSEC_PER_SEC) /
+                              ((HDA_MAX_CYCLE_VALUE + 1) * runtime->rate));
+
+       *system = convert_art_to_tsc(tsc_counter);
+
+       return 0;
+}
+
+#else
+static int azx_get_sync_time(ktime_t *device,
+               struct system_counterval_t *system, void *ctx)
+{
+       return -ENXIO;
+}
+#endif
+
+static int azx_get_crosststamp(struct snd_pcm_substream *substream,
+                             struct system_device_crosststamp *xtstamp)
+{
+       return get_device_system_crosststamp(azx_get_sync_time,
+                                       substream, NULL, xtstamp);
+}
+
+static inline bool is_link_time_supported(struct snd_pcm_runtime *runtime,
+                               struct snd_pcm_audio_tstamp_config *ts)
+{
+       if (runtime->hw.info & SNDRV_PCM_INFO_HAS_LINK_SYNCHRONIZED_ATIME)
+               if (ts->type_requested == SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_SYNCHRONIZED)
+                       return true;
+
+       return false;
+}
+
 static int azx_get_time_info(struct snd_pcm_substream *substream,
                        struct timespec *system_ts, struct timespec *audio_ts,
                        struct snd_pcm_audio_tstamp_config *audio_tstamp_config,
                        struct snd_pcm_audio_tstamp_report *audio_tstamp_report)
 {
        struct azx_dev *azx_dev = get_azx_dev(substream);
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       struct system_device_crosststamp xtstamp;
+       int ret;
        u64 nsec;
 
        if ((substream->runtime->hw.info & SNDRV_PCM_INFO_HAS_LINK_ATIME) &&
@@ -361,8 +528,37 @@ static int azx_get_time_info(struct snd_pcm_substream *substream,
                audio_tstamp_report->accuracy_report = 1; /* rest of structure is valid */
                audio_tstamp_report->accuracy = 42; /* 24 MHz WallClock == 42ns resolution */
 
-       } else
+       } else if (is_link_time_supported(runtime, audio_tstamp_config)) {
+
+               ret = azx_get_crosststamp(substream, &xtstamp);
+               if (ret)
+                       return ret;
+
+               switch (runtime->tstamp_type) {
+               case SNDRV_PCM_TSTAMP_TYPE_MONOTONIC:
+                       return -EINVAL;
+
+               case SNDRV_PCM_TSTAMP_TYPE_MONOTONIC_RAW:
+                       *system_ts = ktime_to_timespec(xtstamp.sys_monoraw);
+                       break;
+
+               default:
+                       *system_ts = ktime_to_timespec(xtstamp.sys_realtime);
+                       break;
+
+               }
+
+               *audio_ts = ktime_to_timespec(xtstamp.device);
+
+               audio_tstamp_report->actual_type =
+                       SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_SYNCHRONIZED;
+               audio_tstamp_report->accuracy_report = 1;
+               /* 24 MHz WallClock == 42ns resolution */
+               audio_tstamp_report->accuracy = 42;
+
+       } else {
                audio_tstamp_report->actual_type = SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT;
+       }
 
        return 0;
 }