[alsa-devel] [PATCH] ASoC - Add support for upto 16 channels on OMAP MCBSP

[Liam Girdwood]

From: Graeme Gregory <gg at slimlogic.co.uk>

This patch increases the number of supported audio channels from 4
to 16 and was sponsored by Shotspotter inc.

Signed-off-by: Graeme Gregory <gg at slimlogic.co.uk>
Signed-off-by: Liam Girdwood <lrg at slimlogic.co.uk>
---
 sound/soc/omap/omap-mcbsp.c |   71 +++++++++++++++++++++++++++++-------------
 1 files changed, 49 insertions(+), 22 deletions(-)

diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c
index 3341f49..290ef2f 100644
--- a/sound/soc/omap/omap-mcbsp.c
+++ b/sound/soc/omap/omap-mcbsp.c
@@ -49,6 +49,8 @@ struct omap_mcbsp_data {
 	 */
 	int				active;
 	int				configured;
+	unsigned int			in_freq;
+	int				clk_div;
 };
 
 #define to_mcbsp(priv)	container_of((priv), struct omap_mcbsp_data, bus_id)
@@ -257,7 +259,7 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 	int dma, bus_id = mcbsp_data->bus_id, id = cpu_dai->id;
 	int wlen, channels, wpf, sync_mode = OMAP_DMA_SYNC_ELEMENT;
 	unsigned long port;
-	unsigned int format;
+	unsigned int format, frame_size, div;
 
 	if (cpu_class_is_omap1()) {
 		dma = omap1_dma_reqs[bus_id][substream->stream];
@@ -294,27 +296,23 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 
 	format = mcbsp_data->fmt & SND_SOC_DAIFMT_FORMAT_MASK;
 	wpf = channels = params_channels(params);
-	switch (channels) {
-	case 2:
-		if (format == SND_SOC_DAIFMT_I2S) {
-			/* Use dual-phase frames */
-			regs->rcr2	|= RPHASE;
-			regs->xcr2	|= XPHASE;
-			/* Set 1 word per (McBSP) frame for phase1 and phase2 */
-			wpf--;
-			regs->rcr2	|= RFRLEN2(wpf - 1);
-			regs->xcr2	|= XFRLEN2(wpf - 1);
-		}
-	case 1:
-	case 4:
+	if (channels == 2 && format == SND_SOC_DAIFMT_I2S) {
+		/* Use dual-phase frames */
+		regs->rcr2	|= RPHASE;
+		regs->xcr2	|= XPHASE;
+		/* Set 1 word per (McBSP) frame for phase1 and phase2 */
+		wpf--;
+		regs->rcr2	|= RFRLEN2(wpf - 1);
+		regs->xcr2	|= XFRLEN2(wpf - 1);
 		/* Set word per (McBSP) frame for phase1 */
 		regs->rcr1	|= RFRLEN1(wpf - 1);
 		regs->xcr1	|= XFRLEN1(wpf - 1);
-		break;
-	default:
+	} else if (channels > 0 && channels < 17) {
+		regs->rcr1	|= RFRLEN1(wpf - 1);
+		regs->xcr1	|= XFRLEN1(wpf - 1);
+	} else
 		/* Unsupported number of channels */
 		return -EINVAL;
-	}
 
 	switch (params_format(params)) {
 	case SNDRV_PCM_FORMAT_S16_LE:
@@ -330,6 +328,34 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 		return -EINVAL;
 	}
 
+	/* Default div to 1 if it wasn't set by machine driver, otherwise
+	 * use set div as the maximum clock value
+	 */
+	div = mcbsp_data->clk_div ? mcbsp_data->clk_div : 1;
+
+	/* calc best frame size for rate and clock divider */
+	do {
+		frame_size = (mcbsp_data->in_freq / div) / params_rate(params);
+		pr_debug("freq %d, rate %d, frame size %d, div %d\n",
+				mcbsp_data->in_freq, params_rate(params), frame_size, div);
+
+		if (frame_size > 256)
+			div++;
+	} while (frame_size > 256);
+
+	/* Check we can fit the requested number of channels into our
+	 * calculated frame size
+	 */
+	if ((channels * wlen) > frame_size) {
+		printk(KERN_ERR
+			"OMAP-MCBSP: cannot fit channels in frame size\n");
+		return -EINVAL;
+	}
+
+	/* Set the actual clkdiv to use for this samplerate */
+	regs->srgr1 &= ~CLKGDV(0xFF);
+	regs->srgr1 |= CLKGDV(div - 1);
+
 	/* Set FS period and length in terms of bit clock periods */
 	switch (format) {
 	case SND_SOC_DAIFMT_I2S:
@@ -338,7 +364,7 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 		break;
 	case SND_SOC_DAIFMT_DSP_A:
 	case SND_SOC_DAIFMT_DSP_B:
-		regs->srgr2	|= FPER(wlen * channels - 1);
+		regs->srgr2	|= FPER(frame_size - 1);
 		regs->srgr1	|= FWID(0);
 		break;
 	}
@@ -449,12 +475,11 @@ static int omap_mcbsp_dai_set_clkdiv(struct snd_soc_dai *cpu_dai,
 				     int div_id, int div)
 {
 	struct omap_mcbsp_data *mcbsp_data = to_mcbsp(cpu_dai->private_data);
-	struct omap_mcbsp_reg_cfg *regs = &mcbsp_data->regs;
 
 	if (div_id != OMAP_MCBSP_CLKGDV)
 		return -ENODEV;
 
-	regs->srgr1	|= CLKGDV(div - 1);
+	mcbsp_data->clk_div = div;
 
 	return 0;
 }
@@ -554,6 +579,8 @@ static int omap_mcbsp_dai_set_dai_sysclk(struct snd_soc_dai *cpu_dai,
 	struct omap_mcbsp_reg_cfg *regs = &mcbsp_data->regs;
 	int err = 0;
 
+	mcbsp_data->in_freq = freq;
+
 	switch (clk_id) {
 	case OMAP_MCBSP_SYSCLK_CLK:
 		regs->srgr2	|= CLKSM;
@@ -598,13 +625,13 @@ static struct snd_soc_dai_ops omap_mcbsp_dai_ops = {
 	.id = (link_id),					\
 	.playback = {						\
 		.channels_min = 1,				\
-		.channels_max = 4,				\
+		.channels_max = 16,				\
 		.rates = OMAP_MCBSP_RATES,			\
 		.formats = SNDRV_PCM_FMTBIT_S16_LE,		\
 	},							\
 	.capture = {						\
 		.channels_min = 1,				\
-		.channels_max = 4,				\
+		.channels_max = 16,				\
 		.rates = OMAP_MCBSP_RATES,			\
 		.formats = SNDRV_PCM_FMTBIT_S16_LE,		\
 	},							\
-- 
1.6.3.3