[alsa-devel] [RFC PATCH 20/34] ASoC: sun8i-codec: Support 8/20/24-bit word sizes

Samuel Holland
2020-02-17T06:56:05Z

The codec hardware natively supports 8, 16, 20, and 24-bit word sizes.
However, it only supports slot widths that are a multiple of 16 bits.
So we can only support the 20-bit and 24-bit formats that are padded to
32 bits. This doesn't cost anything, because the DMA controller on the
CPU side only supports power-of-two byte sizes anyway.

S8, S16_LE, and S24_LE were tested using a modified version of the
sun4i-i2s driver as the CPU end of the DAI link. S20_LE was not tested
due to poor userspace support; it should work the same.

In 8 bit mono mode, the computed BCLK/LRCK divider will be less than the
minimum value 16. This is fine; there will just be padding after the
data bits, similar to how S20_LE and S24_LE always have padding.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---
sound/soc/sunxi/sun8i-codec.c | 47 ++++++++++++++++++++++++-----------
1 file changed, 32 insertions(+), 15 deletions(-)

diff --git a/sound/soc/sunxi/sun8i-codec.c b/sound/soc/sunxi/sun8i-codec.c
index 2df899daec67..b915e62fa005 100644
--- a/sound/soc/sunxi/sun8i-codec.c
+++ b/sound/soc/sunxi/sun8i-codec.c
@@ -45,7 +45,6 @@
#define SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV 9
#define SUN8I_AIF1CLK_CTRL_AIF1_LRCK_DIV 6
#define SUN8I_AIF1CLK_CTRL_AIF1_WORD_SIZ 4
-#define SUN8I_AIF1CLK_CTRL_AIF1_WORD_SIZ_16 (1 << 4)
#define SUN8I_AIF1CLK_CTRL_AIF1_DATA_FMT 2
#define SUN8I_AIF1CLK_CTRL_AIF1_MONO_PCM 1
#define SUN8I_AIF1_ADCDAT_CTRL 0x044
@@ -87,6 +86,10 @@
#define SUN8I_AIF1CLK_CTRL_AIF1_WORD_SIZ_MASK GENMASK(5, 4)
#define SUN8I_AIF1CLK_CTRL_AIF1_DATA_FMT_MASK GENMASK(3, 2)

+#define SUN8I_AIF_PCM_FMTS (SNDRV_PCM_FMTBIT_S8|\
+ SNDRV_PCM_FMTBIT_S16_LE|\
+ SNDRV_PCM_FMTBIT_S20_LE|\
+ SNDRV_PCM_FMTBIT_S24_LE)
#define SUN8I_AIF_PCM_RATES (SNDRV_PCM_RATE_8000_48000|\
SNDRV_PCM_RATE_96000|\
SNDRV_PCM_RATE_192000|\
@@ -307,7 +310,9 @@ static int sun8i_codec_get_lrck_div(unsigned int channels,
{
unsigned int div = word_size * channels;

- if (div < 16 || div > 256)
+ if (div < 16)
+ div = 16;
+ if (div > 256)
return -EINVAL;

return ilog2(div) - 4;
@@ -318,27 +323,19 @@ static int sun8i_codec_hw_params(struct snd_pcm_substream *substream,
struct snd_soc_dai *dai)
{
struct sun8i_codec *scodec = snd_soc_component_get_drvdata(dai->component);
+ unsigned int slot_width = params_physical_width(params);
unsigned int channels = params_channels(params);
int sample_rate, lrck_div;
u8 bclk_div;
u32 value;

- /*
- * The CPU DAI handles only a sample of 16 bits. Configure the
- * codec to handle this type of sample resolution.
- */
- regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
- SUN8I_AIF1CLK_CTRL_AIF1_WORD_SIZ_MASK,
- SUN8I_AIF1CLK_CTRL_AIF1_WORD_SIZ_16);
-
bclk_div = sun8i_codec_get_bclk_div(scodec, params_rate(params),
- channels, 16);
+ channels, slot_width);
regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV_MASK,
bclk_div << SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV);

- lrck_div = sun8i_codec_get_lrck_div(channels,
- params_physical_width(params));
+ lrck_div = sun8i_codec_get_lrck_div(channels, slot_width);
if (lrck_div < 0)
return lrck_div;

@@ -346,6 +343,26 @@ static int sun8i_codec_hw_params(struct snd_pcm_substream *substream,
SUN8I_AIF1CLK_CTRL_AIF1_LRCK_DIV_MASK,
lrck_div << SUN8I_AIF1CLK_CTRL_AIF1_LRCK_DIV);

+ switch (params_width(params)) {
+ case 8:
+ value = 0x0;
+ break;
+ case 16:
+ value = 0x1;
+ break;
+ case 20:
+ value = 0x2;
+ break;
+ case 24:
+ value = 0x3;
+ break;
+ default:
+ return -EINVAL;
+ }
+ regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
+ SUN8I_AIF1CLK_CTRL_AIF1_WORD_SIZ_MASK,
+ value << SUN8I_AIF1CLK_CTRL_AIF1_WORD_SIZ);
+
value = channels == 1;
regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
BIT(SUN8I_AIF1CLK_CTRL_AIF1_MONO_PCM),
@@ -533,7 +550,7 @@ static struct snd_soc_dai_driver sun8i_codec_dai = {
.channels_min = 1,
.channels_max = 2,
.rates = SUN8I_AIF_PCM_RATES,
- .formats = SNDRV_PCM_FMTBIT_S16_LE,
+ .formats = SUN8I_AIF_PCM_FMTS,
},
/* capture capabilities */
.capture = {
@@ -541,7 +558,7 @@ static struct snd_soc_dai_driver sun8i_codec_dai = {
.channels_min = 1,
.channels_max = 2,
.rates = SUN8I_AIF_PCM_RATES,
- .formats = SNDRV_PCM_FMTBIT_S16_LE,
+ .formats = SUN8I_AIF_PCM_FMTS,
.sig_bits = 24,
},
/* pcm operations */