[PATCH v3] davinci-mcasp: Add support for multichannel playback

[Michal Bachraty <michal.bachraty@streamunlimited.com>]

Davinci McASP has support for I2S multichannel playback.
For I2S playback/receive, each serializer is capable to play 2 channels
(L/R) audio data.Serializer function (Playback-receive-none) is configured
in DT, depending on hardware specification. It is possible to play less
channels than configured in DT. For that purpose,only specific number of
active serializers are enabled. McASP FIFO need to have DMA transfer Bcnt
set to number of enabled serializers, otherwise no data are transfered to
McASP and Alsa generates "DMA/IRQ playback write error (DMA or IRQ trouble?)"
error. For TDM mode, McASP is capable to play or receive 32 channels for one
serializer. McAsp has support for max 16 serializer, therefore max channels
is 32 * 8.

Signed-off-by: Michal Bachraty <michal.bachraty@streamunlimited.com>
---
 sound/soc/davinci/davinci-mcasp.c |   66 ++++++++++++++++++++++++++++++++-----
 sound/soc/davinci/davinci-pcm.c   |   16 +++++----
 sound/soc/davinci/davinci-pcm.h   |    1 +
 3 files changed, 68 insertions(+), 15 deletions(-)

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index d2ca682..0a1af1a 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -235,6 +235,10 @@
 #define DISMOD		(val)(val<<2)
 #define TXSTATE		BIT(4)
 #define RXSTATE		BIT(5)
+#define SRMOD_MASK	3
+#define SRMOD_INACTIVE	0
+#define SRMOD_TX	1
+#define SRMOD_RX	2
 
 /*
  * DAVINCI_MCASP_LBCTL_REG - Loop Back Control Register Bits
@@ -657,12 +661,15 @@ static int davinci_config_channel_size(struct davinci_audio_dev *dev,
 	return 0;
 }
 
-static void davinci_hw_common_param(struct davinci_audio_dev *dev, int stream)
+static int davinci_hw_common_param(struct davinci_audio_dev *dev, int stream,
+				    int channels)
 {
 	int i;
 	u8 tx_ser = 0;
 	u8 rx_ser = 0;
-
+	u8 ser;
+	u8 slots = dev->tdm_slots;
+	u8 max_active_serializers = (channels + slots - 1) / slots;
 	/* Default configuration */
 	mcasp_set_bits(dev->base + DAVINCI_MCASP_PWREMUMGT_REG, MCASP_SOFT);
 
@@ -680,16 +687,42 @@ static void davinci_hw_common_param(struct davinci_audio_dev *dev, int stream)
 	}
 
 	for (i = 0; i < dev->num_serializer; i++) {
+		if (dev->serial_dir[i] == TX_MODE)
+			tx_ser++;
+		if (dev->serial_dir[i] == RX_MODE)
+			rx_ser++;
+	}
+
+	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
+		ser = tx_ser;
+	else
+		ser = rx_ser;
+
+	if (ser < max_active_serializers) {
+		dev_warn(dev->dev, "stream has more channels (%d) than are "
+			"enabled in mcasp (%d)\n", channels, ser * slots);
+		return -EINVAL;
+	}
+
+	tx_ser = 0;
+	rx_ser = 0;
+
+	for (i = 0; i < dev->num_serializer; i++) {
 		mcasp_set_bits(dev->base + DAVINCI_MCASP_XRSRCTL_REG(i),
 					dev->serial_dir[i]);
-		if (dev->serial_dir[i] == TX_MODE) {
+		if (dev->serial_dir[i] == TX_MODE &&
+					tx_ser < max_active_serializers) {
 			mcasp_set_bits(dev->base + DAVINCI_MCASP_PDIR_REG,
 					AXR(i));
 			tx_ser++;
-		} else if (dev->serial_dir[i] == RX_MODE) {
+		} else if (dev->serial_dir[i] == RX_MODE &&
+					rx_ser < max_active_serializers) {
 			mcasp_clr_bits(dev->base + DAVINCI_MCASP_PDIR_REG,
 					AXR(i));
 			rx_ser++;
+		} else {
+			mcasp_mod_bits(dev->base + DAVINCI_MCASP_XRSRCTL_REG(i),
+					SRMOD_INACTIVE, SRMOD_MASK);
 		}
 	}
 
@@ -729,6 +762,8 @@ static void davinci_hw_common_param(struct davinci_audio_dev *dev, int stream)
 				((dev->rxnumevt * rx_ser) << 8), NUMEVT_MASK);
 		}
 	}
+
+	return 0;
 }
 
 static void davinci_hw_param(struct davinci_audio_dev *dev, int stream)
@@ -812,8 +847,14 @@ static int davinci_mcasp_hw_params(struct snd_pcm_substream *substream,
 					&dev->dma_params[substream->stream];
 	int word_length;
 	u8 fifo_level;
+	u8 slots = dev->tdm_slots;
+	int channels;
+	struct snd_interval *pcm_channels = hw_param_interval(params,
+					SNDRV_PCM_HW_PARAM_CHANNELS);
+	channels = pcm_channels->min;
 
-	davinci_hw_common_param(dev, substream->stream);
+	if (davinci_hw_common_param(dev, substream->stream, channels) == -EINVAL)
+		return -EINVAL;
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 		fifo_level = dev->txnumevt;
 	else
@@ -862,6 +903,7 @@ static int davinci_mcasp_hw_params(struct snd_pcm_substream *substream,
 		dma_params->acnt = dma_params->data_type;
 
 	dma_params->fifo_level = fifo_level;
+	dma_params->active_serializers = (channels + slots - 1) / slots;
 	davinci_config_channel_size(dev, word_length);
 
 	return 0;
@@ -936,13 +978,13 @@ static struct snd_soc_dai_driver davinci_mcasp_dai[] = {
 		.name		= "davinci-mcasp.0",
 		.playback	= {
 			.channels_min	= 2,
-			.channels_max 	= 2,
+			.channels_max	= 32 * 16,
 			.rates 		= DAVINCI_MCASP_RATES,
 			.formats	= DAVINCI_MCASP_PCM_FMTS,
 		},
 		.capture 	= {
 			.channels_min 	= 2,
-			.channels_max 	= 2,
+			.channels_max	= 32 * 16,
 			.rates 		= DAVINCI_MCASP_RATES,
 			.formats	= DAVINCI_MCASP_PCM_FMTS,
 		},
@@ -1015,8 +1057,16 @@ static struct snd_platform_data *davinci_mcasp_set_pdata_from_of(
 		pdata->op_mode = val;
 
 	ret = of_property_read_u32(np, "tdm-slots", &val);
-	if (ret >= 0)
+	if (ret >= 0) {
+		if (val < 2 || val > 32) {
+			dev_err(&pdev->dev,
+				"tdm-slots must be in rage [2-32]\n");
+			ret = -EINVAL;
+			goto nodata;
+		}
+
 		pdata->tdm_slots = val;
+	}
 
 	ret = of_property_read_u32(np, "num-serializer", &val);
 	if (ret >= 0)
diff --git a/sound/soc/davinci/davinci-pcm.c b/sound/soc/davinci/davinci-pcm.c
index bb57552..3af8b50 100644
--- a/sound/soc/davinci/davinci-pcm.c
+++ b/sound/soc/davinci/davinci-pcm.c
@@ -182,6 +182,7 @@ static void davinci_pcm_enqueue_dma(struct snd_pcm_substream *substream)
 	unsigned short acnt;
 	unsigned int count;
 	unsigned int fifo_level;
+	unsigned char serializers = prtd->params->active_serializers;
 
 	period_size = snd_pcm_lib_period_bytes(substream);
 	dma_offset = prtd->period * period_size;
@@ -195,14 +196,14 @@ static void davinci_pcm_enqueue_dma(struct snd_pcm_substream *substream)
 	data_type = prtd->params->data_type;
 	count = period_size / data_type;
 	if (fifo_level)
-		count /= fifo_level;
+		count /= fifo_level * serializers;
 
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		src = dma_pos;
 		dst = prtd->params->dma_addr;
 		src_bidx = data_type;
-		dst_bidx = 0;
-		src_cidx = data_type * fifo_level;
+		dst_bidx = 4;
+		src_cidx = data_type * fifo_level * serializers;
 		dst_cidx = 0;
 	} else {
 		src = prtd->params->dma_addr;
@@ -210,7 +211,7 @@ static void davinci_pcm_enqueue_dma(struct snd_pcm_substream *substream)
 		src_bidx = 0;
 		dst_bidx = data_type;
 		src_cidx = 0;
-		dst_cidx = data_type * fifo_level;
+		dst_cidx = data_type * fifo_level * serializers;
 	}
 
 	acnt = prtd->params->acnt;
@@ -224,9 +225,10 @@ static void davinci_pcm_enqueue_dma(struct snd_pcm_substream *substream)
 		edma_set_transfer_params(prtd->asp_link[0], acnt, count, 1, 0,
 							ASYNC);
 	else
-		edma_set_transfer_params(prtd->asp_link[0], acnt, fifo_level,
-							count, fifo_level,
-							ABSYNC);
+		edma_set_transfer_params(prtd->asp_link[0], acnt,
+						fifo_level * serializers,
+						count, fifo_level * serializers,
+						ABSYNC);
 }
 
 static void davinci_pcm_dma_irq(unsigned link, u16 ch_status, void *data)
diff --git a/sound/soc/davinci/davinci-pcm.h b/sound/soc/davinci/davinci-pcm.h
index fbb710c..0d84d32 100644
--- a/sound/soc/davinci/davinci-pcm.h
+++ b/sound/soc/davinci/davinci-pcm.h
@@ -27,6 +27,7 @@ struct davinci_pcm_dma_params {
 	unsigned char data_type;	/* xfer data type */
 	unsigned char convert_mono_stereo;
 	unsigned int fifo_level;
+	unsigned char active_serializers; /* num. of active audio serializers */
 };
 
 int davinci_soc_platform_register(struct device *dev);
-- 
1.7.9.5