ASoC: Add support for BCM2835

This driver adds support for digital audio (I2S)
for the BCM2835 SoC that is used by the
Raspberry Pi. External audio codecs can be
connected to the Raspberry Pi via P5 header.

It relies on cyclic DMA engine support for BCM2835.

Signed-off-by Florian Meier <[email protected]>

sound/soc/bcm/Kconfig new file +6 -0

+	select SND_SOC_GENERIC_DMAENGINE_PCM
+	select REGMAP_MMIO
+	help
+	  Say Y or M if you want to add support for codecs attached to
+	  the BCM2835 I2S interface. You will also need
+	  to select the audio interfaces to support below.

sound/soc/bcm/Kconfig new file +30 -0

+static void bcm2835_i2s_clear_fifos(struct bcm2835_i2s_dev *dev,
+				    bool tx, bool rx)
+{
+	int timeout = 1000;
+	uint32_t syncval;
+	uint32_t csreg;
+	uint32_t i2s_active_state;
+	uint32_t clkreg;
+	uint32_t clk_active_state;
+	uint32_t off;
+	uint32_t clr;
+
+	off =  tx ? BCM2835_I2S_TXON : 0;
+	off |= rx ? BCM2835_I2S_RXON : 0;
+
+	clr =  tx ? BCM2835_I2S_TXCLR : 0;
+	clr |= rx ? BCM2835_I2S_RXCLR : 0;
+
+	/* Backup the current state */
+	regmap_read(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, &csreg);
+	i2s_active_state = csreg & (BCM2835_I2S_RXON | BCM2835_I2S_TXON);
+
+	regmap_read(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG, &clkreg);
+	clk_active_state = clkreg & BCM2835_CLK_ENAB;
+
+	/* Start clock if not running */
+	if (!clk_active_state) {
+		regmap_update_bits(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG,
+			BCM2835_CLK_PASSWD_MASK | BCM2835_CLK_ENAB,
+			BCM2835_CLK_PASSWD | BCM2835_CLK_ENAB);

sound/soc/bcm/Kconfig new file +34 -0

+
+	/* Wait for 2 PCM clock cycles */
+
+	/*
+	 * Toggle the SYNC flag - after 2 PCM clock cycles it can be read back
+	 * FIXME: This does not seem to work for slave mode!
+	 */
+	regmap_read(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, &syncval);
+	syncval &= BCM2835_I2S_SYNC;
+
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG,
+			BCM2835_I2S_SYNC, ~syncval);
+
+	/* Wait for the SYNC flag changing it's state */
+	while (timeout > 0) {
+		timeout--;
+
+		regmap_read(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, &csreg);
+		if ((csreg & BCM2835_I2S_SYNC) != syncval)
+			break;
+	}
+
+	if (timeout <= 0)
+		dev_err(dev->dev, "I2S SYNC error!\n");
+
+	/* Stop clock if it was not running before */
+	if (!clk_active_state)
+		bcm2835_i2s_stop_clock(dev);
+
+	/* Restore I2S state */
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG,
+			BCM2835_I2S_RXON | BCM2835_I2S_TXON, i2s_active_state);
+}
+

sound/soc/bcm/Kconfig new file +4 -0

+
+	return 0;
+}
+

sound/soc/bcm/Kconfig new file +24 -0

+
+static int bcm2835_i2s_probe(struct platform_device *pdev)
+{
+	struct bcm2835_i2s_dev *dev;
+	int i;
+	int ret;
+	struct regmap *regmap[2];
+	struct resource *mem[2];
+
+	/* request both ioareas */
+	for (i = 0; i <= 1; i++) {
+		void __iomem *base;
+
+		mem[i] = platform_get_resource(pdev, IORESOURCE_MEM, i);
+		if (!mem[i]) {
+			dev_err(&pdev->dev, "I2S probe: Memory resource could not be found.\n");
+			return -ENODEV;
+		}
+
+		base = devm_ioremap_resource(&pdev->dev, mem[i]);
+		if (!base) {
+			dev_err(&pdev->dev, "I2S probe: ioremap failed.\n");
+			return -ENOMEM;
+		}

sound/soc/bcm/Kconfig new file +33 -0

+			   GFP_KERNEL);
+	if (!dev) {
+		dev_err(&pdev->dev, "I2S probe: kzalloc failed.\n");
+		return -ENOMEM;
+	}
+
+	dev->i2s_regmap = regmap[0];
+	dev->clk_regmap = regmap[1];
+
+	/* Set the DMA address */
+	dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK].addr =
+		(dma_addr_t)mem[0]->start + BCM2835_I2S_FIFO_A_REG
+					  + BCM2835_VCMMU_SHIFT;
+
+	dev->dma_data[SNDRV_PCM_STREAM_CAPTURE].addr =
+		(dma_addr_t)mem[0]->start + BCM2835_I2S_FIFO_A_REG
+					  + BCM2835_VCMMU_SHIFT;
+
+	/* Store the pdev */
+	dev->dev = &pdev->dev;
+	dev_set_drvdata(&pdev->dev, dev);
+
+	ret = snd_soc_register_component(&pdev->dev,
+			&bcm2835_i2s_component, &bcm2835_i2s_dai, 1);
+
+	if (ret) {
+		dev_err(&pdev->dev, "Could not register DAI: %d\n", ret);
+		ret = -ENOMEM;
+		return ret;
+	}
+
+	ret = bcm2835_pcm_platform_register(&pdev->dev);
+	if (ret) {

sound/soc/bcm/Kconfig new file +2 -0

+	{},
+};

sound/soc/bcm/Kconfig new file +2 -0

+}
+EXPORT_SYMBOL_GPL(bcm2835_pcm_platform_register);