ASoC: Add a generic dmaengine_pcm driver

This patch adds a generic dmaengine PCM driver. It builds on top of the
dmaengine PCM library and adds the missing pieces like DMA channel management,
buffer management and channel configuration. It will be able to replace the
majority of the existing platform specific dmaengine based PCM drivers.
Devicetree is used to map the DMA channels to the PCM device.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Tested-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

include/sound/dmaengine_pcm.h

@@ -72,4 +72,29 @@ void snd_dmaengine_pcm_set_config_from_dai_data(
 	const struct snd_dmaengine_dai_dma_data *dma_data,
 	struct dma_slave_config *config);
 
+/**
+ * struct snd_dmaengine_pcm_config - Configuration data for dmaengine based PCM
+ * @prepare_slave_config: Callback used to fill in the DMA slave_config for a
+ *   PCM substream. Will be called from the PCM drivers hwparams callback.
+ * @pcm_hardware: snd_pcm_hardware struct to be used for the PCM.
+ * @prealloc_buffer_size: Size of the preallocated audio buffer.
+ */
+struct snd_dmaengine_pcm_config {
+	int (*prepare_slave_config)(struct snd_pcm_substream *substream,
+			struct snd_pcm_hw_params *params,
+			struct dma_slave_config *slave_config);
+
+	const struct snd_pcm_hardware *pcm_hardware;
+	unsigned int prealloc_buffer_size;
+};
+
+int snd_dmaengine_pcm_register(struct device *dev,
+	const struct snd_dmaengine_pcm_config *config,
+	unsigned int flags);
+void snd_dmaengine_pcm_unregister(struct device *dev);
+
+int snd_dmaengine_pcm_prepare_slave_config(struct snd_pcm_substream *substream,
+	struct snd_pcm_hw_params *params,
+	struct dma_slave_config *slave_config);
+
 #endif

sound/soc/Kconfig

@@ -29,6 +29,10 @@ config SND_SOC_AC97_BUS
 config SND_SOC_DMAENGINE_PCM
 	bool
 
+config SND_SOC_GENERIC_DMAENGINE_PCM
+	bool
+	select SND_SOC_DMAENGINE_PCM
+
 # All the supported SoCs
 source "sound/soc/atmel/Kconfig"
 source "sound/soc/au1x/Kconfig"

sound/soc/Makefile

@@ -5,6 +5,10 @@ ifneq ($(CONFIG_SND_SOC_DMAENGINE_PCM),)
 snd-soc-core-objs += soc-dmaengine-pcm.o
 endif
 
+ifneq ($(CONFIG_SND_SOC_GENERIC_DMAENGINE_PCM),)
+snd-soc-core-objs += soc-generic-dmaengine-pcm.o
+endif
+
 obj-$(CONFIG_SND_SOC)	+= snd-soc-core.o
 obj-$(CONFIG_SND_SOC)	+= codecs/
 obj-$(CONFIG_SND_SOC)	+= generic/

sound/soc/soc-generic-dmaengine-pcm.c

@@ -0,0 +1,241 @@
+/*
+ *  Copyright (C) 2013, Analog Devices Inc.
+ *	Author: Lars-Peter Clausen <lars@metafoo.de>
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under  the terms of the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/dmaengine.h>
+#include <linux/slab.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <linux/dma-mapping.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+
+#include <sound/dmaengine_pcm.h>
+
+struct dmaengine_pcm {
+	struct dma_chan *chan[SNDRV_PCM_STREAM_CAPTURE + 1];
+	const struct snd_dmaengine_pcm_config *config;
+	struct snd_soc_platform platform;
+};
+
+static struct dmaengine_pcm *soc_platform_to_pcm(struct snd_soc_platform *p)
+{
+	return container_of(p, struct dmaengine_pcm, platform);
+}
+
+/**
+ * snd_dmaengine_pcm_prepare_slave_config() - Generic prepare_slave_config callback
+ * @substream: PCM substream
+ * @params: hw_params
+ * @slave_config: DMA slave config to prepare
+ *
+ * This function can be used as a generic prepare_slave_config callback for
+ * platforms which make use of the snd_dmaengine_dai_dma_data struct for their
+ * DAI DMA data. Internally the function will first call
+ * snd_hwparams_to_dma_slave_config to fill in the slave config based on the
+ * hw_params, followed by snd_dmaengine_set_config_from_dai_data to fill in the
+ * remaining fields based on the DAI DMA data.
+ */
+int snd_dmaengine_pcm_prepare_slave_config(struct snd_pcm_substream *substream,
+	struct snd_pcm_hw_params *params, struct dma_slave_config *slave_config)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_dmaengine_dai_dma_data *dma_data;
+	int ret;
+
+	dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
+
+	ret = snd_hwparams_to_dma_slave_config(substream, params, slave_config);
+	if (ret)
+		return ret;
+
+	snd_dmaengine_pcm_set_config_from_dai_data(substream, dma_data,
+		slave_config);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_prepare_slave_config);
+
+static int dmaengine_pcm_hw_params(struct snd_pcm_substream *substream,
+	struct snd_pcm_hw_params *params)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
+	struct dma_chan *chan = snd_dmaengine_pcm_get_chan(substream);
+	struct dma_slave_config slave_config;
+	int ret;
+
+	if (pcm->config->prepare_slave_config) {
+		ret = pcm->config->prepare_slave_config(substream, params,
+				&slave_config);
+		if (ret)
+			return ret;
+
+		ret = dmaengine_slave_config(chan, &slave_config);
+		if (ret)
+			return ret;
+	}
+
+	return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(params));
+}
+
+static int dmaengine_pcm_open(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
+	struct dma_chan *chan = pcm->chan[substream->stream];
+	int ret;
+
+	ret = snd_soc_set_runtime_hwparams(substream,
+				pcm->config->pcm_hardware);
+	if (ret)
+		return ret;
+
+	return snd_dmaengine_pcm_open(substream, chan);
+}
+
+static struct device *dmaengine_dma_dev(struct dmaengine_pcm *pcm,
+	struct snd_pcm_substream *substream)
+{
+	if (!pcm->chan[substream->stream])
+		return NULL;
+
+	return pcm->chan[substream->stream]->device->dev;
+}
+
+static void dmaengine_pcm_free(struct snd_pcm *pcm)
+{
+	snd_pcm_lib_preallocate_free_for_all(pcm);
+}
+
+static int dmaengine_pcm_new(struct snd_soc_pcm_runtime *rtd)
+{
+	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
+	const struct snd_dmaengine_pcm_config *config = pcm->config;
+	struct snd_pcm_substream *substream;
+	unsigned int i;
+	int ret;
+
+	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
+		substream = rtd->pcm->streams[i].substream;
+		if (!substream)
+			continue;
+
+		if (!pcm->chan[i]) {
+			dev_err(rtd->platform->dev,
+				"Missing dma channel for stream: %d\n", i);
+			ret = -EINVAL;
+			goto err_free;
+		}
+
+		ret = snd_pcm_lib_preallocate_pages(substream,
+				SNDRV_DMA_TYPE_DEV,
+				dmaengine_dma_dev(pcm, substream),
+				config->prealloc_buffer_size,
+				config->pcm_hardware->buffer_bytes_max);
+		if (ret)
+			goto err_free;
+	}
+
+	return 0;
+
+err_free:
+	dmaengine_pcm_free(rtd->pcm);
+	return ret;
+}
+
+static const struct snd_pcm_ops dmaengine_pcm_ops = {
+	.open		= dmaengine_pcm_open,
+	.close		= snd_dmaengine_pcm_close,
+	.ioctl		= snd_pcm_lib_ioctl,
+	.hw_params	= dmaengine_pcm_hw_params,
+	.hw_free	= snd_pcm_lib_free_pages,
+	.trigger	= snd_dmaengine_pcm_trigger,
+	.pointer	= snd_dmaengine_pcm_pointer,
+};
+
+static const struct snd_soc_platform_driver dmaengine_pcm_platform = {
+	.ops		= &dmaengine_pcm_ops,
+	.pcm_new	= dmaengine_pcm_new,
+	.pcm_free	= dmaengine_pcm_free,
+};
+
+static const char * const dmaengine_pcm_dma_channel_names[] = {
+	[SNDRV_PCM_STREAM_PLAYBACK] = "tx",
+	[SNDRV_PCM_STREAM_CAPTURE] = "rx",
+};
+
+/**
+ * snd_dmaengine_pcm_register - Register a dmaengine based PCM device
+ * @dev: The parent device for the PCM device
+ * @config: Platform specific PCM configuration
+ * @flags: Platform specific quirks
+ */
+int snd_dmaengine_pcm_register(struct device *dev,
+	const struct snd_dmaengine_pcm_config *config, unsigned int flags)
+{
+	struct dmaengine_pcm *pcm;
+	unsigned int i;
+
+	if (!dev->of_node)
+		return -EINVAL;
+
+	pcm = kzalloc(sizeof(*pcm), GFP_KERNEL);
+	if (!pcm)
+		return -ENOMEM;
+
+	pcm->config = config;
+
+	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
+		pcm->chan[i] = of_dma_request_slave_channel(dev->of_node,
+					dmaengine_pcm_dma_channel_names[i]);
+	}
+
+	return snd_soc_add_platform(dev, &pcm->platform,
+				&dmaengine_pcm_platform);
+}
+EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_register);
+
+/**
+ * snd_dmaengine_pcm_unregister - Removes a dmaengine based PCM device
+ * @dev: Parent device the PCM was register with
+ *
+ * Removes a dmaengine based PCM device previously registered with
+ * snd_dmaengine_pcm_register.
+ */
+void snd_dmaengine_pcm_unregister(struct device *dev)
+{
+	struct snd_soc_platform *platform;
+	struct dmaengine_pcm *pcm;
+	unsigned int i;
+
+	platform = snd_soc_lookup_platform(dev);
+	if (!platform)
+		return;
+
+	pcm = soc_platform_to_pcm(platform);
+
+	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
+		if (pcm->chan[i])
+			dma_release_channel(pcm->chan[i]);
+	}
+
+	snd_soc_remove_platform(platform);
+	kfree(pcm);
+}
+EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_unregister);
+
+MODULE_LICENSE("GPL");