[PATCH 6/8] iio: adc: stm32-dfsdm: add support for scan mode

[Fabrice Gasnier]

In order to support multiple channels in buffer mode, add support for scan
mode. This is precursor patch to ease support of triggered buffer mode.
Currently, only audio uses buffer mode: Regular continuous conversions
with a single channel (per filter).
DFSDM hardware supports scan mode (only) with injected conversions.
Conversions can be launched by software (JSWSTART), trigger or
synchronously with filter 0 (e.g. JSYNC). Continuous conversion mode isn't
available for injected.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
---
 drivers/iio/adc/stm32-dfsdm-adc.c | 182 +++++++++++++++++++++++++++++---------
 1 file changed, 142 insertions(+), 40 deletions(-)

diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
index b491424..4ead6bf 100644
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -40,7 +40,8 @@
 
 /* Filter configuration */
 #define DFSDM_CR1_CFG_MASK (DFSDM_CR1_RCH_MASK | DFSDM_CR1_RCONT_MASK | \
-			    DFSDM_CR1_RSYNC_MASK)
+			    DFSDM_CR1_RSYNC_MASK | DFSDM_CR1_JSYNC_MASK | \
+			    DFSDM_CR1_JSCAN_MASK)
 
 enum sd_converter_type {
 	DFSDM_AUDIO,
@@ -58,6 +59,8 @@ struct stm32_dfsdm_adc {
 	struct stm32_dfsdm *dfsdm;
 	const struct stm32_dfsdm_dev_data *dev_data;
 	unsigned int fl_id;
+	unsigned int nconv;
+	unsigned long smask;
 
 	/* ADC specific */
 	unsigned int oversamp;
@@ -204,19 +207,39 @@ static int stm32_dfsdm_set_osrs(struct stm32_dfsdm_filter *fl,
 	return 0;
 }
 
-static int stm32_dfsdm_start_channel(struct stm32_dfsdm *dfsdm,
-				     unsigned int ch_id)
+static int stm32_dfsdm_start_channel(struct stm32_dfsdm_adc *adc)
 {
-	return regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(ch_id),
-				  DFSDM_CHCFGR1_CHEN_MASK,
-				  DFSDM_CHCFGR1_CHEN(1));
+	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct regmap *regmap = adc->dfsdm->regmap;
+	const struct iio_chan_spec *chan;
+	unsigned int bit;
+	int ret;
+
+	for_each_set_bit(bit, &adc->smask, sizeof(adc->smask) * BITS_PER_BYTE) {
+		chan = indio_dev->channels + bit;
+		ret = regmap_update_bits(regmap, DFSDM_CHCFGR1(chan->channel),
+					 DFSDM_CHCFGR1_CHEN_MASK,
+					 DFSDM_CHCFGR1_CHEN(1));
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
 }
 
-static void stm32_dfsdm_stop_channel(struct stm32_dfsdm *dfsdm,
-				     unsigned int ch_id)
+static void stm32_dfsdm_stop_channel(struct stm32_dfsdm_adc *adc)
 {
-	regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(ch_id),
-			   DFSDM_CHCFGR1_CHEN_MASK, DFSDM_CHCFGR1_CHEN(0));
+	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct regmap *regmap = adc->dfsdm->regmap;
+	const struct iio_chan_spec *chan;
+	unsigned int bit;
+
+	for_each_set_bit(bit, &adc->smask, sizeof(adc->smask) * BITS_PER_BYTE) {
+		chan = indio_dev->channels + bit;
+		regmap_update_bits(regmap, DFSDM_CHCFGR1(chan->channel),
+				   DFSDM_CHCFGR1_CHEN_MASK,
+				   DFSDM_CHCFGR1_CHEN(0));
+	}
 }
 
 static int stm32_dfsdm_chan_configure(struct stm32_dfsdm *dfsdm,
@@ -241,9 +264,10 @@ static int stm32_dfsdm_chan_configure(struct stm32_dfsdm *dfsdm,
 				  DFSDM_CHCFGR1_CHINSEL(ch->alt_si));
 }
 
-static int stm32_dfsdm_start_filter(struct stm32_dfsdm *dfsdm,
+static int stm32_dfsdm_start_filter(struct stm32_dfsdm_adc *adc,
 				    unsigned int fl_id)
 {
+	struct stm32_dfsdm *dfsdm = adc->dfsdm;
 	int ret;
 
 	/* Enable filter */
@@ -252,7 +276,11 @@ static int stm32_dfsdm_start_filter(struct stm32_dfsdm *dfsdm,
 	if (ret < 0)
 		return ret;
 
-	/* Start conversion */
+	/* Nothing more to do for injected (scan mode/triggered) conversions */
+	if (adc->nconv > 1)
+		return 0;
+
+	/* Software start (single or continuous) regular conversion */
 	return regmap_update_bits(dfsdm->regmap, DFSDM_CR1(fl_id),
 				  DFSDM_CR1_RSWSTART_MASK,
 				  DFSDM_CR1_RSWSTART(1));
@@ -267,12 +295,14 @@ static void stm32_dfsdm_stop_filter(struct stm32_dfsdm *dfsdm,
 }
 
 static int stm32_dfsdm_filter_configure(struct stm32_dfsdm_adc *adc,
-					unsigned int fl_id, unsigned int ch_id)
+					unsigned int fl_id)
 {
 	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
 	struct regmap *regmap = adc->dfsdm->regmap;
 	struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[fl_id];
 	u32 cr1;
+	const struct iio_chan_spec *chan;
+	unsigned int bit, jchg = 0;
 	int ret;
 
 	/* Average integrator oversampling */
@@ -292,14 +322,59 @@ static int stm32_dfsdm_filter_configure(struct stm32_dfsdm_adc *adc,
 	if (ret)
 		return ret;
 
-	/* No scan mode supported for the moment */
-	cr1 = DFSDM_CR1_RCH(ch_id);
+	/*
+	 * DFSDM modes configuration W.R.T audio/iio type modes
+	 * ----------------------------------------------------------------
+	 * Modes         | regular |  regular     | injected | injected   |
+	 *               |         |  continuous  |          | + scan     |
+	 * --------------|---------|--------------|----------|------------|
+	 * single conv   |    x    |              |          |            |
+	 * (1 chan)      |         |              |          |            |
+	 * --------------|---------|--------------|----------|------------|
+	 * 1 Audio chan	 |         | sample freq  |          |            |
+	 *               |         | or sync_mode |          |            |
+	 * --------------|---------|--------------|----------|------------|
+	 * 1 IIO chan	 |         | sample freq  | trigger  |            |
+	 *               |         | or sync_mode |          |            |
+	 * --------------|---------|--------------|----------|------------|
+	 * 2+ IIO chans  |         |              |          | trigger or |
+	 *               |         |              |          | sync_mode  |
+	 * ----------------------------------------------------------------
+	 */
+	if (adc->nconv == 1) {
+		bit = __ffs(adc->smask);
+		chan = indio_dev->channels + bit;
 
-	/* Continuous conversions triggered by SPI clock in buffer mode */
-	if (indio_dev->currentmode & INDIO_BUFFER_SOFTWARE)
-		cr1 |= DFSDM_CR1_RCONT(1);
+		/* Use regular conversion for single channel without trigger */
+		cr1 = DFSDM_CR1_RCH(chan->channel);
 
-	cr1 |= DFSDM_CR1_RSYNC(fl->sync_mode);
+		/* Continuous conversions triggered by SPI clk in buffer mode */
+		if (indio_dev->currentmode & INDIO_BUFFER_SOFTWARE)
+			cr1 |= DFSDM_CR1_RCONT(1);
+
+		cr1 |= DFSDM_CR1_RSYNC(fl->sync_mode);
+	} else {
+		/* Use injected conversion for multiple channels */
+		for_each_set_bit(bit, &adc->smask,
+				 sizeof(adc->smask) * BITS_PER_BYTE) {
+			chan = indio_dev->channels + bit;
+			jchg |= BIT(chan->channel);
+		}
+		ret = regmap_write(regmap, DFSDM_JCHGR(fl_id), jchg);
+		if (ret < 0)
+			return ret;
+
+		/* Use scan mode for multiple channels */
+		cr1 = DFSDM_CR1_JSCAN(1);
+
+		/*
+		 * Continuous conversions not supported in injected mode:
+		 * - use conversions in sync with filter 0
+		 */
+		if (!fl->sync_mode)
+			return -EINVAL;
+		cr1 |= DFSDM_CR1_JSYNC(fl->sync_mode);
+	}
 
 	return regmap_update_bits(regmap, DFSDM_CR1(fl_id), DFSDM_CR1_CFG_MASK,
 				  cr1);
@@ -428,21 +503,20 @@ static ssize_t dfsdm_adc_audio_set_spiclk(struct iio_dev *indio_dev,
 	return len;
 }
 
-static int stm32_dfsdm_start_conv(struct stm32_dfsdm_adc *adc,
-				  const struct iio_chan_spec *chan)
+static int stm32_dfsdm_start_conv(struct stm32_dfsdm_adc *adc)
 {
 	struct regmap *regmap = adc->dfsdm->regmap;
 	int ret;
 
-	ret = stm32_dfsdm_start_channel(adc->dfsdm, chan->channel);
+	ret = stm32_dfsdm_start_channel(adc);
 	if (ret < 0)
 		return ret;
 
-	ret = stm32_dfsdm_filter_configure(adc, adc->fl_id, chan->channel);
+	ret = stm32_dfsdm_filter_configure(adc, adc->fl_id);
 	if (ret < 0)
 		goto stop_channels;
 
-	ret = stm32_dfsdm_start_filter(adc->dfsdm, adc->fl_id);
+	ret = stm32_dfsdm_start_filter(adc, adc->fl_id);
 	if (ret < 0)
 		goto filter_unconfigure;
 
@@ -452,13 +526,12 @@ static int stm32_dfsdm_start_conv(struct stm32_dfsdm_adc *adc,
 	regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
 			   DFSDM_CR1_CFG_MASK, 0);
 stop_channels:
-	stm32_dfsdm_stop_channel(adc->dfsdm, chan->channel);
+	stm32_dfsdm_stop_channel(adc);
 
 	return ret;
 }
 
-static void stm32_dfsdm_stop_conv(struct stm32_dfsdm_adc *adc,
-				  const struct iio_chan_spec *chan)
+static void stm32_dfsdm_stop_conv(struct stm32_dfsdm_adc *adc)
 {
 	struct regmap *regmap = adc->dfsdm->regmap;
 
@@ -467,7 +540,7 @@ static void stm32_dfsdm_stop_conv(struct stm32_dfsdm_adc *adc,
 	regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
 			   DFSDM_CR1_CFG_MASK, 0);
 
-	stm32_dfsdm_stop_channel(adc->dfsdm, chan->channel);
+	stm32_dfsdm_stop_channel(adc);
 }
 
 static int stm32_dfsdm_set_watermark(struct iio_dev *indio_dev,
@@ -557,8 +630,7 @@ static int stm32_dfsdm_adc_dma_start(struct iio_dev *indio_dev)
 {
 	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
 	struct dma_slave_config config = {
-		.src_addr = (dma_addr_t)adc->dfsdm->phys_base +
-			DFSDM_RDATAR(adc->fl_id),
+		.src_addr = (dma_addr_t)adc->dfsdm->phys_base,
 		.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
 	};
 	struct dma_async_tx_descriptor *desc;
@@ -571,6 +643,10 @@ static int stm32_dfsdm_adc_dma_start(struct iio_dev *indio_dev)
 	dev_dbg(&indio_dev->dev, "%s size=%d watermark=%d\n", __func__,
 		adc->buf_sz, adc->buf_sz / 2);
 
+	if (adc->nconv == 1)
+		config.src_addr += DFSDM_RDATAR(adc->fl_id);
+	else
+		config.src_addr += DFSDM_JDATAR(adc->fl_id);
 	ret = dmaengine_slave_config(adc->dma_chan, &config);
 	if (ret)
 		return ret;
@@ -595,9 +671,20 @@ static int stm32_dfsdm_adc_dma_start(struct iio_dev *indio_dev)
 	/* Issue pending DMA requests */
 	dma_async_issue_pending(adc->dma_chan);
 
-	/* Enable DMA transfer*/
-	ret = regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR1(adc->fl_id),
-				 DFSDM_CR1_RDMAEN_MASK, DFSDM_CR1_RDMAEN_MASK);
+	if (adc->nconv == 1) {
+		/* Enable regular DMA transfer*/
+		ret = regmap_update_bits(adc->dfsdm->regmap,
+					 DFSDM_CR1(adc->fl_id),
+					 DFSDM_CR1_RDMAEN_MASK,
+					 DFSDM_CR1_RDMAEN_MASK);
+	} else {
+		/* Enable injected DMA transfer*/
+		ret = regmap_update_bits(adc->dfsdm->regmap,
+					 DFSDM_CR1(adc->fl_id),
+					 DFSDM_CR1_JDMAEN_MASK,
+					 DFSDM_CR1_JDMAEN_MASK);
+	}
+
 	if (ret < 0)
 		goto err_stop_dma;
 
@@ -617,14 +704,26 @@ static void stm32_dfsdm_adc_dma_stop(struct iio_dev *indio_dev)
 		return;
 
 	regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR1(adc->fl_id),
-			   DFSDM_CR1_RDMAEN_MASK, 0);
+			   DFSDM_CR1_RDMAEN_MASK | DFSDM_CR1_JDMAEN_MASK, 0);
 	dmaengine_terminate_all(adc->dma_chan);
 }
 
+static int stm32_dfsdm_update_scan_mode(struct iio_dev *indio_dev,
+					const unsigned long *scan_mask)
+{
+	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
+
+	adc->nconv = bitmap_weight(scan_mask, indio_dev->masklength);
+	adc->smask = *scan_mask;
+
+	dev_dbg(&indio_dev->dev, "nconv=%d mask=%lx\n", adc->nconv, *scan_mask);
+
+	return 0;
+}
+
 static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
 {
 	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
-	const struct iio_chan_spec *chan = &indio_dev->channels[0];
 	int ret;
 
 	/* Reset adc buffer index */
@@ -646,7 +745,7 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
 		goto stop_dfsdm;
 	}
 
-	ret = stm32_dfsdm_start_conv(adc, chan);
+	ret = stm32_dfsdm_start_conv(adc);
 	if (ret) {
 		dev_err(&indio_dev->dev, "Can't start conversion\n");
 		goto err_stop_dma;
@@ -668,9 +767,8 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
 static int stm32_dfsdm_predisable(struct iio_dev *indio_dev)
 {
 	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
-	const struct iio_chan_spec *chan = &indio_dev->channels[0];
 
-	stm32_dfsdm_stop_conv(adc, chan);
+	stm32_dfsdm_stop_conv(adc);
 
 	stm32_dfsdm_adc_dma_stop(indio_dev);
 
@@ -756,7 +854,9 @@ static int stm32_dfsdm_single_conv(struct iio_dev *indio_dev,
 	if (ret < 0)
 		goto stop_dfsdm;
 
-	ret = stm32_dfsdm_start_conv(adc, chan);
+	adc->nconv = 1;
+	adc->smask = BIT(chan->scan_index);
+	ret = stm32_dfsdm_start_conv(adc);
 	if (ret < 0) {
 		regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR2(adc->fl_id),
 				   DFSDM_CR2_REOCIE_MASK, DFSDM_CR2_REOCIE(0));
@@ -777,7 +877,7 @@ static int stm32_dfsdm_single_conv(struct iio_dev *indio_dev,
 	else
 		ret = IIO_VAL_INT;
 
-	stm32_dfsdm_stop_conv(adc, chan);
+	stm32_dfsdm_stop_conv(adc);
 
 stop_dfsdm:
 	stm32_dfsdm_stop_dfsdm(adc->dfsdm);
@@ -882,11 +982,13 @@ static const struct iio_info stm32_dfsdm_info_audio = {
 	.hwfifo_set_watermark = stm32_dfsdm_set_watermark,
 	.read_raw = stm32_dfsdm_read_raw,
 	.write_raw = stm32_dfsdm_write_raw,
+	.update_scan_mode = stm32_dfsdm_update_scan_mode,
 };
 
 static const struct iio_info stm32_dfsdm_info_adc = {
 	.read_raw = stm32_dfsdm_read_raw,
 	.write_raw = stm32_dfsdm_write_raw,
+	.update_scan_mode = stm32_dfsdm_update_scan_mode,
 };
 
 static irqreturn_t stm32_dfsdm_irq(int irq, void *arg)
-- 
2.7.4