ASoC: stm32: add DFSDM DAI support

Add driver to handle DAI interface for PDM microphones connected
to Digital Filter for Sigma Delta Modulators IP.

Signed-off-by: Arnaud Pouliquen <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/stm/Kconfig

···
 	help
 	  Say Y if you want to enable S/PDIF capture for STM32
 
+config SND_SOC_STM32_DFSDM
+	tristate "SoC Audio support for STM32 DFSDM"
+	depends on (ARCH_STM32 && OF && STM32_DFSDM_ADC) || COMPILE_TEST
+	depends on SND_SOC
+	select SND_SOC_GENERIC_DMAENGINE_PCM
+	select SND_SOC_DMIC
+	select IIO_BUFFER_CB
+	help
+	  Select this option to enable the STM32 Digital Filter
+	  for Sigma Delta Modulators (DFSDM) driver used
+	  in various STM32 series for digital microphone capture.
 endmenu

sound/soc/stm/Makefile

···
 # SPDIFRX
 snd-soc-stm32-spdifrx-objs := stm32_spdifrx.o
 obj-$(CONFIG_SND_SOC_STM32_SPDIFRX) += snd-soc-stm32-spdifrx.o
+
+#DFSDM
+obj-$(CONFIG_SND_SOC_STM32_DFSDM) += stm32_adfsdm.o

sound/soc/stm/stm32_adfsdm.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file is part of STM32 DFSDM ASoC DAI driver
+ *
+ * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
+ * Authors: Arnaud Pouliquen <[e-mail]>
+ *          Olivier Moysan <[e-mail]>
+ */
+
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/consumer.h>
+#include <linux/iio/adc/stm32-dfsdm-adc.h>
+
+#include <sound/pcm.h>
+#include <sound/soc.h>
+
+#define STM32_ADFSDM_DRV_NAME "stm32-adfsdm"
+
+#define DFSDM_MAX_PERIOD_SIZE	(PAGE_SIZE / 2)
+#define DFSDM_MAX_PERIODS	6
+
+struct stm32_adfsdm_priv {
+	struct snd_soc_dai_driver dai_drv;
+	struct snd_pcm_substream *substream;
+	struct device *dev;
+
+	/* IIO */
+	struct iio_channel *iio_ch;
+	struct iio_cb_buffer *iio_cb;
+	bool iio_active;
+
+	/* PCM buffer */
+	unsigned char *pcm_buff;
+	unsigned int pos;
+};
+
+static const struct snd_pcm_hardware stm32_adfsdm_pcm_hw = {
+	.info = SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER |
+	    SNDRV_PCM_INFO_PAUSE,
+	.formats = SNDRV_PCM_FMTBIT_S32_LE,
+
+	.rate_min = 8000,
+	.rate_max = 32000,
+
+	.channels_min = 1,
+	.channels_max = 1,
+
+	.periods_min = 2,
+	.periods_max = DFSDM_MAX_PERIODS,
+
+	.period_bytes_max = DFSDM_MAX_PERIOD_SIZE,
+	.buffer_bytes_max = DFSDM_MAX_PERIODS * DFSDM_MAX_PERIOD_SIZE
+};
+
+static void stm32_adfsdm_shutdown(struct snd_pcm_substream *substream,
+				  struct snd_soc_dai *dai)
+{
+	struct stm32_adfsdm_priv *priv = snd_soc_dai_get_drvdata(dai);
+
+	if (priv->iio_active) {
+		iio_channel_stop_all_cb(priv->iio_cb);
+		priv->iio_active = false;
+	}
+}
+
+static int stm32_adfsdm_dai_prepare(struct snd_pcm_substream *substream,
+				    struct snd_soc_dai *dai)
+{
+	struct stm32_adfsdm_priv *priv = snd_soc_dai_get_drvdata(dai);
+	int ret;
+
+	ret = iio_write_channel_attribute(priv->iio_ch,
+					  substream->runtime->rate, 0,
+					  IIO_CHAN_INFO_SAMP_FREQ);
+	if (ret < 0) {
+		dev_err(dai->dev, "%s: Failed to set %d sampling rate\n",
+			__func__, substream->runtime->rate);
+		return ret;
+	}
+
+	if (!priv->iio_active) {
+		ret = iio_channel_start_all_cb(priv->iio_cb);
+		if (!ret)
+			priv->iio_active = true;
+		else
+			dev_err(dai->dev, "%s: IIO channel start failed (%d)\n",
+				__func__, ret);
+	}
+
+	return ret;
+}
+
+static int stm32_adfsdm_set_sysclk(struct snd_soc_dai *dai, int clk_id,
+				   unsigned int freq, int dir)
+{
+	struct stm32_adfsdm_priv *priv = snd_soc_dai_get_drvdata(dai);
+	ssize_t size;
+	char str_freq[10];
+
+	dev_dbg(dai->dev, "%s: Enter for freq %d\n", __func__, freq);
+
+	/* Set IIO frequency if CODEC is master as clock comes from SPI_IN */
+
+	snprintf(str_freq, sizeof(str_freq), "%d\n", freq);
+	size = iio_write_channel_ext_info(priv->iio_ch, "spi_clk_freq",
+					  str_freq, sizeof(str_freq));
+	if (size != sizeof(str_freq)) {
+		dev_err(dai->dev, "%s: Failed to set SPI clock\n",
+			__func__);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static const struct snd_soc_dai_ops stm32_adfsdm_dai_ops = {
+	.shutdown = stm32_adfsdm_shutdown,
+	.prepare = stm32_adfsdm_dai_prepare,
+	.set_sysclk = stm32_adfsdm_set_sysclk,
+};
+
+static const struct snd_soc_dai_driver stm32_adfsdm_dai = {
+	.capture = {
+		    .channels_min = 1,
+		    .channels_max = 1,
+		    .formats = SNDRV_PCM_FMTBIT_S32_LE,
+		    .rates = (SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_16000 |
+			      SNDRV_PCM_RATE_32000),
+		    },
+	.ops = &stm32_adfsdm_dai_ops,
+};
+
+static const struct snd_soc_component_driver stm32_adfsdm_dai_component = {
+	.name = "stm32_dfsdm_audio",
+};
+
+static int stm32_afsdm_pcm_cb(const void *data, size_t size, void *private)
+{
+	struct stm32_adfsdm_priv *priv = private;
+	struct snd_soc_pcm_runtime *rtd = priv->substream->private_data;
+	u8 *pcm_buff = priv->pcm_buff;
+	u8 *src_buff = (u8 *)data;
+	unsigned int buff_size = snd_pcm_lib_buffer_bytes(priv->substream);
+	unsigned int period_size = snd_pcm_lib_period_bytes(priv->substream);
+	unsigned int old_pos = priv->pos;
+	unsigned int cur_size = size;
+
+	dev_dbg(rtd->dev, "%s: buff_add :%p, pos = %d, size = %zu\n",
+		__func__, &pcm_buff[priv->pos], priv->pos, size);
+
+	if ((priv->pos + size) > buff_size) {
+		memcpy(&pcm_buff[priv->pos], src_buff, buff_size - priv->pos);
+		cur_size -= buff_size - priv->pos;
+		priv->pos = 0;
+	}
+
+	memcpy(&pcm_buff[priv->pos], &src_buff[size - cur_size], cur_size);
+	priv->pos = (priv->pos + cur_size) % buff_size;
+
+	if (cur_size != size || (old_pos && (old_pos % period_size < size)))
+		snd_pcm_period_elapsed(priv->substream);
+
+	return 0;
+}
+
+static int stm32_adfsdm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct stm32_adfsdm_priv *priv =
+		snd_soc_dai_get_drvdata(rtd->cpu_dai);
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+		priv->pos = 0;
+		return stm32_dfsdm_get_buff_cb(priv->iio_ch->indio_dev,
+					       stm32_afsdm_pcm_cb, priv);
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+	case SNDRV_PCM_TRIGGER_STOP:
+		return stm32_dfsdm_release_buff_cb(priv->iio_ch->indio_dev);
+	}
+
+	return -EINVAL;
+}
+
+static int stm32_adfsdm_pcm_open(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct stm32_adfsdm_priv *priv = snd_soc_dai_get_drvdata(rtd->cpu_dai);
+	int ret;
+
+	ret =  snd_soc_set_runtime_hwparams(substream, &stm32_adfsdm_pcm_hw);
+	if (!ret)
+		priv->substream = substream;
+
+	return ret;
+}
+
+static int stm32_adfsdm_pcm_close(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct stm32_adfsdm_priv *priv =
+		snd_soc_dai_get_drvdata(rtd->cpu_dai);
+
+	snd_pcm_lib_free_pages(substream);
+	priv->substream = NULL;
+
+	return 0;
+}
+
+static snd_pcm_uframes_t stm32_adfsdm_pcm_pointer(
+					    struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct stm32_adfsdm_priv *priv =
+		snd_soc_dai_get_drvdata(rtd->cpu_dai);
+
+	return bytes_to_frames(substream->runtime, priv->pos);
+}
+
+static int stm32_adfsdm_pcm_hw_params(struct snd_pcm_substream *substream,
+				      struct snd_pcm_hw_params *params)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct stm32_adfsdm_priv *priv =
+		snd_soc_dai_get_drvdata(rtd->cpu_dai);
+	int ret;
+
+	ret =  snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(params));
+	if (ret < 0)
+		return ret;
+	priv->pcm_buff = substream->runtime->dma_area;
+
+	return iio_channel_cb_set_buffer_watermark(priv->iio_cb,
+						   params_period_size(params));
+}
+
+static int stm32_adfsdm_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+	snd_pcm_lib_free_pages(substream);
+
+	return 0;
+}
+
+static struct snd_pcm_ops stm32_adfsdm_pcm_ops = {
+	.open		= stm32_adfsdm_pcm_open,
+	.close		= stm32_adfsdm_pcm_close,
+	.hw_params	= stm32_adfsdm_pcm_hw_params,
+	.hw_free	= stm32_adfsdm_pcm_hw_free,
+	.trigger	= stm32_adfsdm_trigger,
+	.pointer	= stm32_adfsdm_pcm_pointer,
+};
+
+static int stm32_adfsdm_pcm_new(struct snd_soc_pcm_runtime *rtd)
+{
+	struct snd_pcm *pcm = rtd->pcm;
+	struct stm32_adfsdm_priv *priv =
+		snd_soc_dai_get_drvdata(rtd->cpu_dai);
+	unsigned int size = DFSDM_MAX_PERIODS * DFSDM_MAX_PERIOD_SIZE;
+
+	return snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
+						     priv->dev, size, size);
+}
+
+static void stm32_adfsdm_pcm_free(struct snd_pcm *pcm)
+{
+	struct snd_pcm_substream *substream;
+	struct snd_soc_pcm_runtime *rtd;
+	struct stm32_adfsdm_priv *priv;
+
+	substream = pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream;
+	if (substream) {
+		rtd = substream->private_data;
+		priv = snd_soc_dai_get_drvdata(rtd->cpu_dai);
+
+		snd_pcm_lib_preallocate_free_for_all(pcm);
+	}
+}
+
+static struct snd_soc_platform_driver stm32_adfsdm_soc_platform = {
+	.ops		= &stm32_adfsdm_pcm_ops,
+	.pcm_new	= stm32_adfsdm_pcm_new,
+	.pcm_free	= stm32_adfsdm_pcm_free,
+};
+
+static const struct of_device_id stm32_adfsdm_of_match[] = {
+	{.compatible = "st,stm32h7-dfsdm-dai"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, stm32_adfsdm_of_match);
+
+static int stm32_adfsdm_probe(struct platform_device *pdev)
+{
+	struct stm32_adfsdm_priv *priv;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = &pdev->dev;
+	priv->dai_drv = stm32_adfsdm_dai;
+
+	dev_set_drvdata(&pdev->dev, priv);
+
+	ret = devm_snd_soc_register_component(&pdev->dev,
+					      &stm32_adfsdm_dai_component,
+					      &priv->dai_drv, 1);
+	if (ret < 0)
+		return ret;
+
+	/* Associate iio channel */
+	priv->iio_ch  = devm_iio_channel_get_all(&pdev->dev);
+	if (IS_ERR(priv->iio_ch))
+		return PTR_ERR(priv->iio_ch);
+
+	priv->iio_cb = iio_channel_get_all_cb(&pdev->dev, NULL, NULL);
+	if (IS_ERR(priv->iio_cb))
+		return PTR_ERR(priv->iio_ch);
+
+	ret = devm_snd_soc_register_platform(&pdev->dev,
+					     &stm32_adfsdm_soc_platform);
+	if (ret < 0)
+		dev_err(&pdev->dev, "%s: Failed to register PCM platform\n",
+			__func__);
+
+	return ret;
+}
+
+static struct platform_driver stm32_adfsdm_driver = {
+	.driver = {
+		   .name = STM32_ADFSDM_DRV_NAME,
+		   .of_match_table = stm32_adfsdm_of_match,
+		   },
+	.probe = stm32_adfsdm_probe,
+};
+
+module_platform_driver(stm32_adfsdm_driver);
+
+MODULE_DESCRIPTION("stm32 DFSDM DAI driver");
+MODULE_AUTHOR("Arnaud Pouliquen <[e-mail]>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" STM32_ADFSDM_DRV_NAME);