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@bootlin.com --- 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];