ASoC: dwc: Add PIO PCM extension

A PCM extension was added to I2S driver so that audio
samples are transferred using PIO mode.

The PCM supports two channels @ 16 or 32 bits with rates
32k, 44.1k and 48k.

Although the mainline I2S driver uses ALSA DMA engine the
I2S controller can be built without DMA support, therefore
this is the reason why this extension was added.

Signed-off-by: Jose Abreu <[email protected]>
Cc: Carlos Palminha <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Alexey Brodkin <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: joabreu

sound/soc/dwc/Kconfig

@@ -7,4 +7,13 @@ config SND_DESIGNWARE_I2S
 	 Synopsys desigwnware I2S device. The device supports upto
 	 maximum of 8 channels each for play and record.
 
+config SND_DESIGNWARE_PCM
+	tristate "PCM PIO extension for I2S driver"
+	depends on SND_DESIGNWARE_I2S
+	help
+	 Say Y, M or N if you want to add a custom ALSA extension that registers
+	 a PCM and uses PIO to transfer data.
+
+	 This functionality is specially suited for I2S devices that don't have
+	 DMA support.
 

sound/soc/dwc/Makefile

@@ -1,3 +1,4 @@
 # SYNOPSYS Platform Support
 obj-$(CONFIG_SND_DESIGNWARE_I2S) += designware_i2s.o
+obj-$(CONFIG_SND_DESIGNWARE_PCM) += designware_pcm.o
 

sound/soc/dwc/designware_i2s.c

@@ -24,90 +24,7 @@
 #include <sound/pcm_params.h>
 #include <sound/soc.h>
 #include <sound/dmaengine_pcm.h>
-
-/* common register for all channel */
-#define IER		0x000
-#define IRER		0x004
-#define ITER		0x008
-#define CER		0x00C
-#define CCR		0x010
-#define RXFFR		0x014
-#define TXFFR		0x018
-
-/* I2STxRxRegisters for all channels */
-#define LRBR_LTHR(x)	(0x40 * x + 0x020)
-#define RRBR_RTHR(x)	(0x40 * x + 0x024)
-#define RER(x)		(0x40 * x + 0x028)
-#define TER(x)		(0x40 * x + 0x02C)
-#define RCR(x)		(0x40 * x + 0x030)
-#define TCR(x)		(0x40 * x + 0x034)
-#define ISR(x)		(0x40 * x + 0x038)
-#define IMR(x)		(0x40 * x + 0x03C)
-#define ROR(x)		(0x40 * x + 0x040)
-#define TOR(x)		(0x40 * x + 0x044)
-#define RFCR(x)		(0x40 * x + 0x048)
-#define TFCR(x)		(0x40 * x + 0x04C)
-#define RFF(x)		(0x40 * x + 0x050)
-#define TFF(x)		(0x40 * x + 0x054)
-
-/* I2SCOMPRegisters */
-#define I2S_COMP_PARAM_2	0x01F0
-#define I2S_COMP_PARAM_1	0x01F4
-#define I2S_COMP_VERSION	0x01F8
-#define I2S_COMP_TYPE		0x01FC
-
-/*
- * Component parameter register fields - define the I2S block's
- * configuration.
- */
-#define	COMP1_TX_WORDSIZE_3(r)	(((r) & GENMASK(27, 25)) >> 25)
-#define	COMP1_TX_WORDSIZE_2(r)	(((r) & GENMASK(24, 22)) >> 22)
-#define	COMP1_TX_WORDSIZE_1(r)	(((r) & GENMASK(21, 19)) >> 19)
-#define	COMP1_TX_WORDSIZE_0(r)	(((r) & GENMASK(18, 16)) >> 16)
-#define	COMP1_TX_CHANNELS(r)	(((r) & GENMASK(10, 9)) >> 9)
-#define	COMP1_RX_CHANNELS(r)	(((r) & GENMASK(8, 7)) >> 7)
-#define	COMP1_RX_ENABLED(r)	(((r) & BIT(6)) >> 6)
-#define	COMP1_TX_ENABLED(r)	(((r) & BIT(5)) >> 5)
-#define	COMP1_MODE_EN(r)	(((r) & BIT(4)) >> 4)
-#define	COMP1_FIFO_DEPTH_GLOBAL(r)	(((r) & GENMASK(3, 2)) >> 2)
-#define	COMP1_APB_DATA_WIDTH(r)	(((r) & GENMASK(1, 0)) >> 0)
-
-#define	COMP2_RX_WORDSIZE_3(r)	(((r) & GENMASK(12, 10)) >> 10)
-#define	COMP2_RX_WORDSIZE_2(r)	(((r) & GENMASK(9, 7)) >> 7)
-#define	COMP2_RX_WORDSIZE_1(r)	(((r) & GENMASK(5, 3)) >> 3)
-#define	COMP2_RX_WORDSIZE_0(r)	(((r) & GENMASK(2, 0)) >> 0)
-
-/* Number of entries in WORDSIZE and DATA_WIDTH parameter registers */
-#define	COMP_MAX_WORDSIZE	(1 << 3)
-#define	COMP_MAX_DATA_WIDTH	(1 << 2)
-
-#define MAX_CHANNEL_NUM		8
-#define MIN_CHANNEL_NUM		2
-
-union dw_i2s_snd_dma_data {
-	struct i2s_dma_data pd;
-	struct snd_dmaengine_dai_dma_data dt;
-};
-
-struct dw_i2s_dev {
-	void __iomem *i2s_base;
-	struct clk *clk;
-	int active;
-	unsigned int capability;
-	unsigned int quirks;
-	unsigned int i2s_reg_comp1;
-	unsigned int i2s_reg_comp2;
-	struct device *dev;
-	u32 ccr;
-	u32 xfer_resolution;
-	u32 fifo_th;
-
-	/* data related to DMA transfers b/w i2s and DMAC */
-	union dw_i2s_snd_dma_data play_dma_data;
-	union dw_i2s_snd_dma_data capture_dma_data;
-	struct i2s_clk_config_data config;
-	int (*i2s_clk_cfg)(struct i2s_clk_config_data *config);
-};
+#include "local.h"
 
 static inline void i2s_write_reg(void __iomem *io_base, int reg, u32 val)
 {
@@ -181,6 +98,52 @@ static inline void i2s_enable_irqs(struct dw_i2s_dev *dev, u32 stream,
 	}
 }
 
+static irqreturn_t i2s_irq_handler(int irq, void *dev_id)
+{
+	struct dw_i2s_dev *dev = dev_id;
+	bool irq_valid = false;
+	u32 isr[4];
+	int i;
+
+	for (i = 0; i < 4; i++)
+		isr[i] = i2s_read_reg(dev->i2s_base, ISR(i));
+
+	i2s_clear_irqs(dev, SNDRV_PCM_STREAM_PLAYBACK);
+	i2s_clear_irqs(dev, SNDRV_PCM_STREAM_CAPTURE);
+
+	for (i = 0; i < 4; i++) {
+		/*
+		 * Check if TX fifo is empty. If empty fill FIFO with samples
+		 * NOTE: Only two channels supported
+		 */
+		if ((isr[i] & ISR_TXFE) && (i == 0) && dev->use_pio) {
+			dw_pcm_push_tx(dev);
+			irq_valid = true;
+		}
+
+		/* Data available. Record mode not supported in PIO mode */
+		if (isr[i] & ISR_RXDA)
+			irq_valid = true;
+
+		/* Error Handling: TX */
+		if (isr[i] & ISR_TXFO) {
+			dev_err(dev->dev, "TX overrun (ch_id=%d)\n", i);
+			irq_valid = true;
+		}
+
+		/* Error Handling: TX */
+		if (isr[i] & ISR_RXFO) {
+			dev_err(dev->dev, "RX overrun (ch_id=%d)\n", i);
+			irq_valid = true;
+		}
+	}
+
+	if (irq_valid)
+		return IRQ_HANDLED;
+	else
+		return IRQ_NONE;
+}
+
 static void i2s_start(struct dw_i2s_dev *dev,
 		      struct snd_pcm_substream *substream)
 {
@@ -640,7 +603,7 @@ static int dw_i2s_probe(struct platform_device *pdev)
 	const struct i2s_platform_data *pdata = pdev->dev.platform_data;
 	struct dw_i2s_dev *dev;
 	struct resource *res;
-	int ret;
+	int ret, irq;
 	struct snd_soc_dai_driver *dw_i2s_dai;
 	const char *clk_id;
 
@@ -665,6 +628,16 @@ static int dw_i2s_probe(struct platform_device *pdev)
 
 	dev->dev = &pdev->dev;
 
+	irq = platform_get_irq(pdev, 0);
+	if (irq >= 0) {
+		ret = devm_request_irq(&pdev->dev, irq, i2s_irq_handler, 0,
+				pdev->name, dev);
+		if (ret < 0) {
+			dev_err(&pdev->dev, "failed to request irq\n");
+			return ret;
+		}
+	}
+
 	dev->i2s_reg_comp1 = I2S_COMP_PARAM_1;
 	dev->i2s_reg_comp2 = I2S_COMP_PARAM_2;
 	if (pdata) {
@@ -711,12 +684,24 @@ static int dw_i2s_probe(struct platform_device *pdev)
 
 	if (!pdata) {
 		ret = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL, 0);
-		if (ret) {
+		if (ret == -EPROBE_DEFER) {
+			dev_err(&pdev->dev,
+				"failed to register PCM, deferring probe\n");
+			return ret;
+		} else if (ret) {
 			dev_err(&pdev->dev,
-				"Could not register PCM: %d\n", ret);
-			goto err_clk_disable;
+				"Could not register DMA PCM: %d\n"
+				"falling back to PIO mode\n", ret);
+			ret = dw_pcm_register(pdev);
+			if (ret) {
+				dev_err(&pdev->dev,
+					"Could not register PIO PCM: %d\n",
+					ret);
+				goto err_clk_disable;
+			}
 		}
 	}
+
 	pm_runtime_enable(&pdev->dev);
 	return 0;