[PATCH 13/13] ASoC: ti: davinci-i2s: Opitonally drive DX pin during capture streams
From: Bastien Curutchet
Date: Fri Mar 15 2024 - 07:31:00 EST
The McBSP's DX pin that outputs serial data during playback streams can
be used during capture streams to repeatedly output a chosen pattern.
For instance, this can be useful to drive an active-low signal during
captures (by choosing <0> as output pattern).
Enable this behaviour when the device-tree property 'ti,drive-dx' is
present. DX pin is driven with the provided pattern every time a
capture stream is launched.
This property is not compatible with classic playback stream so
davinci_i2s_trigger() returns an error if a playback stream is started
while 'ti,drive-dx' flag is present.
This has been tested on a board designed of a DAVINCI/OMAP-L138 where
the DX pin is linked to the chip select pin of the converters of the
capture side.
Signed-off-by: Bastien Curutchet <bastien.curutchet@xxxxxxxxxxx>
---
sound/soc/ti/davinci-i2s.c | 74 ++++++++++++++++++++++++++++++++------
1 file changed, 63 insertions(+), 11 deletions(-)
diff --git a/sound/soc/ti/davinci-i2s.c b/sound/soc/ti/davinci-i2s.c
index 13e349e7a6ec..e289a84bdd6a 100644
--- a/sound/soc/ti/davinci-i2s.c
+++ b/sound/soc/ti/davinci-i2s.c
@@ -101,6 +101,9 @@
#define DAVINCI_MCBSP_PCR_FSRM (1 << 10)
#define DAVINCI_MCBSP_PCR_FSXM (1 << 11)
+#define PLAYBACK_CLOCK 1
+#define CAPTURE_CLOCK 0
+
enum {
DAVINCI_MCBSP_WORD_8 = 0,
DAVINCI_MCBSP_WORD_12,
@@ -164,6 +167,8 @@ struct davinci_mcbsp_dev {
bool sync_err;
bool free_run;
+ bool drive_dx;
+ u32 dx_val;
};
static inline void davinci_mcbsp_write_reg(struct davinci_mcbsp_dev *dev,
@@ -187,6 +192,19 @@ static void toggle_clock(struct davinci_mcbsp_dev *dev, int playback)
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, dev->pcr);
}
+static int davinci_drive_dx(struct davinci_mcbsp_dev *dev)
+{
+ unsigned int spcr;
+
+ davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_DXR_REG, dev->dx_val);
+
+ spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
+ spcr |= DAVINCI_MCBSP_SPCR_XRST;
+ davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
+
+ return 0;
+}
+
static void davinci_mcbsp_start(struct davinci_mcbsp_dev *dev,
struct snd_pcm_substream *substream)
{
@@ -194,6 +212,9 @@ static void davinci_mcbsp_start(struct davinci_mcbsp_dev *dev,
u32 spcr;
u32 mask = playback ? DAVINCI_MCBSP_SPCR_XRST : DAVINCI_MCBSP_SPCR_RRST;
+ if (!playback && dev->drive_dx)
+ davinci_drive_dx(dev);
+
/* Enable transmitter or receiver */
spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
spcr |= mask;
@@ -212,9 +233,17 @@ static void davinci_mcbsp_stop(struct davinci_mcbsp_dev *dev, int playback)
/* Reset transmitter/receiver and sample rate/frame sync generators */
spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
spcr &= ~(DAVINCI_MCBSP_SPCR_GRST | DAVINCI_MCBSP_SPCR_FRST);
- spcr &= playback ? ~DAVINCI_MCBSP_SPCR_XRST : ~DAVINCI_MCBSP_SPCR_RRST;
- davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
- toggle_clock(dev, playback);
+
+ if (!playback) {
+ spcr &= ~DAVINCI_MCBSP_SPCR_RRST;
+ davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
+ toggle_clock(dev, CAPTURE_CLOCK);
+ }
+ if (playback || dev->drive_dx) {
+ spcr &= ~DAVINCI_MCBSP_SPCR_XRST;
+ davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
+ toggle_clock(dev, PLAYBACK_CLOCK);
+ }
}
static int davinci_i2s_tdm_word_length(int tdm_slot_width)
@@ -408,6 +437,10 @@ static int davinci_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
}
if (inv_fs == true)
pcr ^= (DAVINCI_MCBSP_PCR_FSXP | DAVINCI_MCBSP_PCR_FSRP);
+
+ if (dev->drive_dx)
+ pcr |= DAVINCI_MCBSP_PCR_CLKRP;
+
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SRGR_REG, srgr);
dev->pcr = pcr;
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, pcr);
@@ -562,6 +595,9 @@ static int davinci_i2s_hw_params(struct snd_pcm_substream *substream,
xcr |= DAVINCI_MCBSP_XCR_XDATDLY(1);
}
+ if (dev->drive_dx)
+ xcr |= DAVINCI_MCBSP_XCR_XDATDLY(2);
+
if (params_channels(params) == 2) {
element_cnt = 2;
if (double_fmt[fmt] && dev->enable_channel_combine) {
@@ -611,9 +647,9 @@ static int davinci_i2s_hw_params(struct snd_pcm_substream *substream,
xcr |= DAVINCI_MCBSP_XCR_XWDLEN1(mcbsp_word_length) |
DAVINCI_MCBSP_XCR_XWDLEN2(mcbsp_word_length);
- if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK || dev->drive_dx)
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_XCR_REG, xcr);
- else
+ if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_RCR_REG, rcr);
pr_debug("%s - %d srgr=%X\n", __func__, __LINE__, srgr);
@@ -628,16 +664,21 @@ static int davinci_i2s_prepare(struct snd_pcm_substream *substream,
struct davinci_mcbsp_dev *dev = snd_soc_dai_get_drvdata(dai);
int playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
u32 spcr;
- u32 mask = playback ? DAVINCI_MCBSP_SPCR_XRST : DAVINCI_MCBSP_SPCR_RRST;
davinci_mcbsp_stop(dev, playback);
spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
- if (spcr & mask) {
+ if (spcr & DAVINCI_MCBSP_SPCR_XRST) {
/* start off disabled */
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG,
- spcr & ~mask);
- toggle_clock(dev, playback);
+ spcr & ~DAVINCI_MCBSP_SPCR_XRST);
+ toggle_clock(dev, PLAYBACK_CLOCK);
+ }
+ if (spcr & DAVINCI_MCBSP_SPCR_RRST) {
+ /* start off disabled */
+ davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG,
+ spcr & ~DAVINCI_MCBSP_SPCR_RRST);
+ toggle_clock(dev, CAPTURE_CLOCK);
}
if (dev->pcr & (DAVINCI_MCBSP_PCR_FSXM | DAVINCI_MCBSP_PCR_FSRM |
DAVINCI_MCBSP_PCR_CLKXM | DAVINCI_MCBSP_PCR_CLKRM)) {
@@ -646,7 +687,7 @@ static int davinci_i2s_prepare(struct snd_pcm_substream *substream,
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
}
- if (playback) {
+ if (playback || dev->drive_dx) {
/* Enable the transmitter */
spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
spcr |= DAVINCI_MCBSP_SPCR_XRST;
@@ -659,7 +700,7 @@ static int davinci_i2s_prepare(struct snd_pcm_substream *substream,
spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
spcr &= ~DAVINCI_MCBSP_SPCR_XRST;
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
- toggle_clock(dev, playback);
+ toggle_clock(dev, PLAYBACK_CLOCK);
}
return 0;
@@ -672,6 +713,11 @@ static int davinci_i2s_trigger(struct snd_pcm_substream *substream, int cmd,
int ret = 0;
int playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
+ if (playback && dev->drive_dx) {
+ dev_err(dev->dev, "Playback is not allowed when drive-cs flag is set\n");
+ return -EINVAL;
+ }
+
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
case SNDRV_PCM_TRIGGER_RESUME:
@@ -779,6 +825,12 @@ static int davinci_i2s_probe(struct platform_device *pdev)
dev->free_run = !of_property_read_bool(pdev->dev.of_node, "ti,disable-free-run");
dev->sync_err = of_property_read_bool(pdev->dev.of_node, "ti,enable-sync-err");
+ dev->drive_dx = false;
+ ret = of_property_read_u32(pdev->dev.of_node, "ti,drive-dx", &dev->dx_val);
+ if (ret && ret != -EINVAL)
+ return ret;
+ if (!ret)
+ dev->drive_dx = true;
/* setup DMA, first TX, then RX */
dma_data = &dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK];
--
2.43.2