[PATCH v4 1/3] ASoC: atmel_ssc_dai: if not provided, default to sensible dividers

Peter Rosin
2016-11-15T18:38:13Z

When this driver masters BCLK and/or LRCLK, and noone has stated
differently, assume that all the bits of a frame are used.

This relieves the cpu dai users from the duty to fill in the dividers for
the common case.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
sound/soc/atmel/atmel_ssc_dai.c | 83 +++++++++++++++++++++++++++++++++++++----
sound/soc/atmel/atmel_ssc_dai.h | 1 +
2 files changed, 77 insertions(+), 7 deletions(-)

diff --git a/sound/soc/atmel/atmel_ssc_dai.c b/sound/soc/atmel/atmel_ssc_dai.c
index 16e459aedffe..a1e2c5682dcd 100644
--- a/sound/soc/atmel/atmel_ssc_dai.c
+++ b/sound/soc/atmel/atmel_ssc_dai.c
@@ -380,6 +380,7 @@ static void atmel_ssc_shutdown(struct snd_pcm_substream *substream,
ssc_writel(ssc_p->ssc->regs, CR, SSC_BIT(CR_SWRST));
/* Clear the SSC dividers */
ssc_p->cmr_div = ssc_p->tcmr_period = ssc_p->rcmr_period = 0;
+ ssc_p->forced_divider = 0;
}
spin_unlock_irq(&ssc_p->lock);

@@ -426,14 +427,17 @@ static int atmel_ssc_set_dai_clkdiv(struct snd_soc_dai *cpu_dai,
else
if (div != ssc_p->cmr_div)
return -EBUSY;
+ ssc_p->forced_divider |= BIT(ATMEL_SSC_CMR_DIV);
break;

case ATMEL_SSC_TCMR_PERIOD:
ssc_p->tcmr_period = div;
+ ssc_p->forced_divider |= BIT(ATMEL_SSC_TCMR_PERIOD);
break;

case ATMEL_SSC_RCMR_PERIOD:
ssc_p->rcmr_period = div;
+ ssc_p->forced_divider |= BIT(ATMEL_SSC_RCMR_PERIOD);
break;

default:
@@ -443,6 +447,28 @@ static int atmel_ssc_set_dai_clkdiv(struct snd_soc_dai *cpu_dai,
return 0;
}

+/* Is the cpu-dai master of the frame clock? */
+static int atmel_ssc_cfs(struct atmel_ssc_info *ssc_p)
+{
+ switch (ssc_p->daifmt & SND_SOC_DAIFMT_MASTER_MASK) {
+ case SND_SOC_DAIFMT_CBM_CFS:
+ case SND_SOC_DAIFMT_CBS_CFS:
+ return 1;
+ }
+ return 0;
+}
+
+/* Is the cpu-dai master of the bit clock? */
+static int atmel_ssc_cbs(struct atmel_ssc_info *ssc_p)
+{
+ switch (ssc_p->daifmt & SND_SOC_DAIFMT_MASTER_MASK) {
+ case SND_SOC_DAIFMT_CBS_CFM:
+ case SND_SOC_DAIFMT_CBS_CFS:
+ return 1;
+ }
+ return 0;
+}
+
/*
* Configure the SSC.
*/
@@ -459,6 +485,9 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
u32 tfmr, rfmr, tcmr, rcmr;
int ret;
int fslen, fslen_ext;
+ u32 cmr_div;
+ u32 tcmr_period;
+ u32 rcmr_period;

/*
* Currently, there is only one set of dma params for
@@ -470,6 +499,46 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
else
dir = 1;

+ /*
+ * If the cpu dai should provide BCLK, but noone has provided the
+ * divider needed for that to work, fall back to something sensible.
+ */
+ cmr_div = ssc_p->cmr_div;
+ if (!(ssc_p->forced_divider & BIT(ATMEL_SSC_CMR_DIV)) &&
+ atmel_ssc_cbs(ssc_p)) {
+ int bclk_rate = snd_soc_params_to_bclk(params);
+
+ if (bclk_rate < 0) {
+ dev_err(dai->dev, "unable to calculate cmr_div: %d\n",
+ bclk_rate);
+ return bclk_rate;
+ }
+
+ cmr_div = DIV_ROUND_CLOSEST(ssc_p->mck_rate, 2 * bclk_rate);
+ }
+
+ /*
+ * If the cpu dai should provide LRCLK, but noone has provided the
+ * dividers needed for that to work, fall back to something sensible.
+ */
+ tcmr_period = ssc_p->tcmr_period;
+ rcmr_period = ssc_p->rcmr_period;
+ if (atmel_ssc_cfs(ssc_p)) {
+ int frame_size = snd_soc_params_to_frame_size(params);
+
+ if (frame_size < 0) {
+ dev_err(dai->dev,
+ "unable to calculate tx/rx cmr_period: %d\n",
+ frame_size);
+ return frame_size;
+ }
+
+ if (!(ssc_p->forced_divider & BIT(ATMEL_SSC_TCMR_PERIOD)))
+ tcmr_period = frame_size / 2 - 1;
+ if (!(ssc_p->forced_divider & BIT(ATMEL_SSC_RCMR_PERIOD)))
+ rcmr_period = frame_size / 2 - 1;
+ }
+
dma_params = ssc_p->dma_params[dir];

channels = params_channels(params);
@@ -524,7 +593,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
fslen_ext = (bits - 1) / 16;
fslen = (bits - 1) % 16;

- rcmr = SSC_BF(RCMR_PERIOD, ssc_p->rcmr_period)
+ rcmr = SSC_BF(RCMR_PERIOD, rcmr_period)
| SSC_BF(RCMR_STTDLY, START_DELAY)
| SSC_BF(RCMR_START, SSC_START_FALLING_RF)
| SSC_BF(RCMR_CKI, SSC_CKI_RISING)
@@ -540,7 +609,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
| SSC_BF(RFMR_LOOP, 0)
| SSC_BF(RFMR_DATLEN, (bits - 1));

- tcmr = SSC_BF(TCMR_PERIOD, ssc_p->tcmr_period)
+ tcmr = SSC_BF(TCMR_PERIOD, tcmr_period)
| SSC_BF(TCMR_STTDLY, START_DELAY)
| SSC_BF(TCMR_START, SSC_START_FALLING_RF)
| SSC_BF(TCMR_CKI, SSC_CKI_FALLING)
@@ -606,7 +675,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
fslen_ext = (bits - 1) / 16;
fslen = (bits - 1) % 16;

- rcmr = SSC_BF(RCMR_PERIOD, ssc_p->rcmr_period)
+ rcmr = SSC_BF(RCMR_PERIOD, rcmr_period)
| SSC_BF(RCMR_STTDLY, START_DELAY)
| SSC_BF(RCMR_START, SSC_START_FALLING_RF)
| SSC_BF(RCMR_CKI, SSC_CKI_RISING)
@@ -623,7 +692,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
| SSC_BF(RFMR_LOOP, 0)
| SSC_BF(RFMR_DATLEN, (bits - 1));

- tcmr = SSC_BF(TCMR_PERIOD, ssc_p->tcmr_period)
+ tcmr = SSC_BF(TCMR_PERIOD, tcmr_period)
| SSC_BF(TCMR_STTDLY, START_DELAY)
| SSC_BF(TCMR_START, SSC_START_FALLING_RF)
| SSC_BF(TCMR_CKI, SSC_CKI_FALLING)
@@ -650,7 +719,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
* MCK divider, and the BCLK signal is output
* on the SSC TK line.
*/
- rcmr = SSC_BF(RCMR_PERIOD, ssc_p->rcmr_period)
+ rcmr = SSC_BF(RCMR_PERIOD, rcmr_period)
| SSC_BF(RCMR_STTDLY, 1)
| SSC_BF(RCMR_START, SSC_START_RISING_RF)
| SSC_BF(RCMR_CKI, SSC_CKI_RISING)
@@ -665,7 +734,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
| SSC_BF(RFMR_LOOP, 0)
| SSC_BF(RFMR_DATLEN, (bits - 1));

- tcmr = SSC_BF(TCMR_PERIOD, ssc_p->tcmr_period)
+ tcmr = SSC_BF(TCMR_PERIOD, tcmr_period)
| SSC_BF(TCMR_STTDLY, 1)
| SSC_BF(TCMR_START, SSC_START_RISING_RF)
| SSC_BF(TCMR_CKI, SSC_CKI_FALLING)
@@ -760,7 +829,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
}

/* set SSC clock mode register */
- ssc_writel(ssc_p->ssc->regs, CMR, ssc_p->cmr_div);
+ ssc_writel(ssc_p->ssc->regs, CMR, cmr_div);

/* set receive clock mode and format */
ssc_writel(ssc_p->ssc->regs, RCMR, rcmr);
diff --git a/sound/soc/atmel/atmel_ssc_dai.h b/sound/soc/atmel/atmel_ssc_dai.h
index 80b153857a88..75194f582131 100644
--- a/sound/soc/atmel/atmel_ssc_dai.h
+++ b/sound/soc/atmel/atmel_ssc_dai.h
@@ -113,6 +113,7 @@ struct atmel_ssc_info {
unsigned short cmr_div;
unsigned short tcmr_period;
unsigned short rcmr_period;
+ unsigned int forced_divider;
struct atmel_pcm_dma_params *dma_params[2];
struct atmel_ssc_state ssc_state;
unsigned long mck_rate;
--
2.1.4