ASoC: Add support for the Analog Devices AXI-SPDIF driver

This patch adds a ASoC driver for the AXI-SPDIF softcore. The core implements a
simple SPDIF transmitter and is used on some Analog Devices' reference designs
for various FPGA platforms. For now the driver only support the PL330 as the the
DMA controller.

The driver uses the generic PCM dmaengine driver for its PCM. The only
restriction is that we need to set the SND_DMAENGINE_PCM_FLAG_NO_RESIDUE flag as
the dmaengine driver for the DMA core (PL330) that is used with this core has no
residue reporting capabilities yet. This will be fixed in the future though.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/adi/Kconfig

@@ -11,3 +11,11 @@ config SND_SOC_ADI_AXI_I2S
 	select REGMAP_MMIO
 	help
 	  ASoC driver for the Analog Devices AXI-I2S softcore peripheral.
+
+config SND_SOC_ADI_AXI_SPDIF
+	tristate "AXI-SPDIF support"
+	depends on SND_SOC_ADI
+	select SND_SOC_GENERIC_DMAENGINE_PCM
+	select REGMAP_MMIO
+	help
+	  ASoC driver for the Analog Devices AXI-SPDIF softcore peripheral.

sound/soc/adi/Makefile

 snd-soc-adi-axi-i2s-objs := axi-i2s.o
+snd-soc-adi-axi-spdif-objs := axi-spdif.o
 
 obj-$(CONFIG_SND_SOC_ADI_AXI_I2S) += snd-soc-adi-axi-i2s.o
+obj-$(CONFIG_SND_SOC_ADI_AXI_SPDIF) += snd-soc-adi-axi-spdif.o

sound/soc/adi/axi-spdif.c

+/*
+ * Copyright (C) 2012-2013, Analog Devices Inc.
+ * Author: Lars-Peter Clausen <lars@metafoo.de>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/clk.h>
+#include <linux/regmap.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/initval.h>
+#include <sound/dmaengine_pcm.h>
+
+#define AXI_SPDIF_REG_CTRL	0x0
+#define AXI_SPDIF_REG_STAT	0x4
+#define AXI_SPDIF_REG_TX_FIFO	0xc
+
+#define AXI_SPDIF_CTRL_TXDATA BIT(1)
+#define AXI_SPDIF_CTRL_TXEN BIT(0)
+#define AXI_SPDIF_CTRL_CLKDIV_OFFSET 8
+#define AXI_SPDIF_CTRL_CLKDIV_MASK (0xff << 8)
+
+#define AXI_SPDIF_FREQ_44100	(0x0 << 6)
+#define AXI_SPDIF_FREQ_48000	(0x1 << 6)
+#define AXI_SPDIF_FREQ_32000	(0x2 << 6)
+#define AXI_SPDIF_FREQ_NA	(0x3 << 6)
+
+struct axi_spdif {
+	struct regmap *regmap;
+	struct clk *clk;
+	struct clk *clk_ref;
+
+	struct snd_dmaengine_dai_dma_data dma_data;
+
+	struct snd_ratnum ratnum;
+	struct snd_pcm_hw_constraint_ratnums rate_constraints;
+};
+
+static int axi_spdif_trigger(struct snd_pcm_substream *substream, int cmd,
+	struct snd_soc_dai *dai)
+{
+	struct axi_spdif *spdif = snd_soc_dai_get_drvdata(dai);
+	unsigned int val;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		val = AXI_SPDIF_CTRL_TXDATA;
+		break;
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		val = 0;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	regmap_update_bits(spdif->regmap, AXI_SPDIF_REG_CTRL,
+		AXI_SPDIF_CTRL_TXDATA, val);
+
+	return 0;
+}
+
+static int axi_spdif_hw_params(struct snd_pcm_substream *substream,
+	struct snd_pcm_hw_params *params, struct snd_soc_dai *dai)
+{
+	struct axi_spdif *spdif = snd_soc_dai_get_drvdata(dai);
+	unsigned int rate = params_rate(params);
+	unsigned int clkdiv, stat;
+
+	switch (params_rate(params)) {
+	case 32000:
+		stat = AXI_SPDIF_FREQ_32000;
+		break;
+	case 44100:
+		stat = AXI_SPDIF_FREQ_44100;
+		break;
+	case 48000:
+		stat = AXI_SPDIF_FREQ_48000;
+		break;
+	default:
+		stat = AXI_SPDIF_FREQ_NA;
+		break;
+	}
+
+	clkdiv = DIV_ROUND_CLOSEST(clk_get_rate(spdif->clk_ref),
+			rate * 64 * 2) - 1;
+	clkdiv <<= AXI_SPDIF_CTRL_CLKDIV_OFFSET;
+
+	regmap_write(spdif->regmap, AXI_SPDIF_REG_STAT, stat);
+	regmap_update_bits(spdif->regmap, AXI_SPDIF_REG_CTRL,
+		AXI_SPDIF_CTRL_CLKDIV_MASK, clkdiv);
+
+	return 0;
+}
+
+static int axi_spdif_dai_probe(struct snd_soc_dai *dai)
+{
+	struct axi_spdif *spdif = snd_soc_dai_get_drvdata(dai);
+
+	snd_soc_dai_init_dma_data(dai, &spdif->dma_data, NULL);
+
+	return 0;
+}
+
+static int axi_spdif_startup(struct snd_pcm_substream *substream,
+	struct snd_soc_dai *dai)
+{
+	struct axi_spdif *spdif = snd_soc_dai_get_drvdata(dai);
+	int ret;
+
+	ret = snd_pcm_hw_constraint_ratnums(substream->runtime, 0,
+			   SNDRV_PCM_HW_PARAM_RATE,
+			   &spdif->rate_constraints);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(spdif->clk_ref);
+	if (ret)
+		return ret;
+
+	regmap_update_bits(spdif->regmap, AXI_SPDIF_REG_CTRL,
+		AXI_SPDIF_CTRL_TXEN, AXI_SPDIF_CTRL_TXEN);
+
+	return 0;
+}
+
+static void axi_spdif_shutdown(struct snd_pcm_substream *substream,
+	struct snd_soc_dai *dai)
+{
+	struct axi_spdif *spdif = snd_soc_dai_get_drvdata(dai);
+
+	regmap_update_bits(spdif->regmap, AXI_SPDIF_REG_CTRL,
+		AXI_SPDIF_CTRL_TXEN, 0);
+
+	clk_disable_unprepare(spdif->clk_ref);
+}
+
+static const struct snd_soc_dai_ops axi_spdif_dai_ops = {
+	.startup = axi_spdif_startup,
+	.shutdown = axi_spdif_shutdown,
+	.trigger = axi_spdif_trigger,
+	.hw_params = axi_spdif_hw_params,
+};
+
+static struct snd_soc_dai_driver axi_spdif_dai = {
+	.probe = axi_spdif_dai_probe,
+	.playback = {
+		.channels_min = 2,
+		.channels_max = 2,
+		.rates = SNDRV_PCM_RATE_KNOT,
+		.formats = SNDRV_PCM_FMTBIT_S16_LE,
+	},
+	.ops = &axi_spdif_dai_ops,
+};
+
+static const struct snd_soc_component_driver axi_spdif_component = {
+	.name = "axi-spdif",
+};
+
+static const struct regmap_config axi_spdif_regmap_config = {
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.max_register = AXI_SPDIF_REG_STAT,
+};
+
+static int axi_spdif_probe(struct platform_device *pdev)
+{
+	struct axi_spdif *spdif;
+	struct resource *res;
+	void __iomem *base;
+	int ret;
+
+	spdif = devm_kzalloc(&pdev->dev, sizeof(*spdif), GFP_KERNEL);
+	if (!spdif)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, spdif);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_request_and_ioremap(&pdev->dev, res);
+	if (!base)
+		return -EBUSY;
+
+	spdif->regmap = devm_regmap_init_mmio(&pdev->dev, base,
+					    &axi_spdif_regmap_config);
+	if (IS_ERR(spdif->regmap))
+		return PTR_ERR(spdif->regmap);
+
+	spdif->clk = devm_clk_get(&pdev->dev, "axi");
+	if (IS_ERR(spdif->clk))
+		return PTR_ERR(spdif->clk);
+
+	spdif->clk_ref = devm_clk_get(&pdev->dev, "ref");
+	if (IS_ERR(spdif->clk_ref))
+		return PTR_ERR(spdif->clk_ref);
+
+	ret = clk_prepare_enable(spdif->clk);
+	if (ret)
+		return ret;
+
+	spdif->dma_data.addr = res->start + AXI_SPDIF_REG_TX_FIFO;
+	spdif->dma_data.addr_width = 4;
+	spdif->dma_data.maxburst = 1;
+
+	spdif->ratnum.num = clk_get_rate(spdif->clk_ref) / 128;
+	spdif->ratnum.den_step = 1;
+	spdif->ratnum.den_min = 1;
+	spdif->ratnum.den_max = 64;
+
+	spdif->rate_constraints.rats = &spdif->ratnum;
+	spdif->rate_constraints.nrats = 1;
+
+	ret = devm_snd_soc_register_component(&pdev->dev, &axi_spdif_component,
+					 &axi_spdif_dai, 1);
+	if (ret)
+		goto err_clk_disable;
+
+	ret = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL,
+			SND_DMAENGINE_PCM_FLAG_NO_RESIDUE);
+	if (ret)
+		goto err_clk_disable;
+
+	return 0;
+
+err_clk_disable:
+	clk_disable_unprepare(spdif->clk);
+	return ret;
+}
+
+static int axi_spdif_dev_remove(struct platform_device *pdev)
+{
+	struct axi_spdif *spdif = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(spdif->clk);
+
+	return 0;
+}
+
+static const struct of_device_id axi_spdif_of_match[] = {
+	{ .compatible = "adi,axi-spdif-tx-1.00.a", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, axi_spdif_of_match);
+
+static struct platform_driver axi_spdif_driver = {
+	.driver = {
+		.name = "axi-spdif",
+		.owner = THIS_MODULE,
+		.of_match_table = axi_spdif_of_match,
+	},
+	.probe = axi_spdif_probe,
+	.remove = axi_spdif_dev_remove,
+};
+module_platform_driver(axi_spdif_driver);
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_DESCRIPTION("AXI SPDIF driver");
+MODULE_LICENSE("GPL");