From: Guneshwor Singh guneshwor.o.singh@intel.com
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 --- sound/pci/hda/hda_controller.c | 198 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 197 insertions(+), 1 deletion(-)
diff --git a/sound/pci/hda/hda_controller.c b/sound/pci/hda/hda_controller.c index 1567fe209e01..2ad3b447483f 100644 --- a/sound/pci/hda/hda_controller.c +++ b/sound/pci/hda/hda_controller.c @@ -27,6 +27,12 @@ #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; }