[PATCH v2] ASoC: fsl_sai: Add isr to deal with error flag

[Nicolin Chen <Guangyu.Chen@freescale.com>]

It's quite cricial to clear error flags because SAI might hang if getting
FIFO underrun during playback (I haven't confirmed the same issue on Rx
overflow though).

So this patch enables those irq and adds isr() to clear the flags so as to
keep playback entirely safe.

Signed-off-by: Nicolin Chen <Guangyu.Chen@freescale.com>
---

Changelog
v2:
 * Mask the active flags only for the following handler.
 * Reset FIFO for FIFO underrun/overflow cases.
 * Enable two error flags only as default.
 * Use dev_warn for two error flags.
 * Only clear those W1C bits.

 sound/soc/fsl/fsl_sai.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++--
 sound/soc/fsl/fsl_sai.h | 15 +++++++++
 2 files changed, 97 insertions(+), 3 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index c4a4231..0bc98bb 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -23,6 +23,71 @@
 
 #include "fsl_sai.h"
 
+#define FSL_SAI_FLAGS (FSL_SAI_CSR_SEIE |\
+		       FSL_SAI_CSR_FEIE)
+
+static irqreturn_t fsl_sai_isr(int irq, void *devid)
+{
+	struct fsl_sai *sai = (struct fsl_sai *)devid;
+	struct device *dev = &sai->pdev->dev;
+	u32 xcsr, mask;
+
+	/* Only handle those what we enabled */
+	mask = (FSL_SAI_FLAGS >> FSL_SAI_CSR_xIE_SHIFT) << FSL_SAI_CSR_xF_SHIFT;
+
+	/* Tx IRQ */
+	regmap_read(sai->regmap, FSL_SAI_TCSR, &xcsr);
+	xcsr &= mask;
+
+	if (xcsr & FSL_SAI_CSR_WSF)
+		dev_dbg(dev, "isr: Start of Tx word detected\n");
+
+	if (xcsr & FSL_SAI_CSR_SEF)
+		dev_warn(dev, "isr: Tx Frame sync error detected\n");
+
+	if (xcsr & FSL_SAI_CSR_FEF) {
+		dev_warn(dev, "isr: Transmit underrun detected\n");
+		/* FIFO reset for safety */
+		xcsr |= FSL_SAI_CSR_FR;
+	}
+
+	if (xcsr & FSL_SAI_CSR_FWF)
+		dev_dbg(dev, "isr: Enabled transmit FIFO is empty\n");
+
+	if (xcsr & FSL_SAI_CSR_FRF)
+		dev_dbg(dev, "isr: Transmit FIFO watermark has been reached\n");
+
+	regmap_update_bits(sai->regmap, FSL_SAI_TCSR,
+			   FSL_SAI_CSR_xF_W_MASK | FSL_SAI_CSR_FR, xcsr);
+
+	/* Rx IRQ */
+	regmap_read(sai->regmap, FSL_SAI_RCSR, &xcsr);
+	xcsr &= mask;
+
+	if (xcsr & FSL_SAI_CSR_WSF)
+		dev_dbg(dev, "isr: Start of Rx word detected\n");
+
+	if (xcsr & FSL_SAI_CSR_SEF)
+		dev_warn(dev, "isr: Rx Frame sync error detected\n");
+
+	if (xcsr & FSL_SAI_CSR_FEF) {
+		dev_warn(dev, "isr: Receive overflow detected\n");
+		/* FIFO reset for safety */
+		xcsr |= FSL_SAI_CSR_FR;
+	}
+
+	if (xcsr & FSL_SAI_CSR_FWF)
+		dev_dbg(dev, "isr: Enabled receive FIFO is full\n");
+
+	if (xcsr & FSL_SAI_CSR_FRF)
+		dev_dbg(dev, "isr: Receive FIFO watermark has been reached\n");
+
+	regmap_update_bits(sai->regmap, FSL_SAI_RCSR,
+			   FSL_SAI_CSR_xF_W_MASK | FSL_SAI_CSR_FR, xcsr);
+
+	return IRQ_HANDLED;
+}
+
 static int fsl_sai_set_dai_sysclk_tr(struct snd_soc_dai *cpu_dai,
 		int clk_id, unsigned int freq, int fsl_dir)
 {
@@ -373,8 +438,8 @@ static int fsl_sai_dai_probe(struct snd_soc_dai *cpu_dai)
 {
 	struct fsl_sai *sai = dev_get_drvdata(cpu_dai->dev);
 
-	regmap_update_bits(sai->regmap, FSL_SAI_TCSR, 0xffffffff, 0x0);
-	regmap_update_bits(sai->regmap, FSL_SAI_RCSR, 0xffffffff, 0x0);
+	regmap_update_bits(sai->regmap, FSL_SAI_TCSR, 0xffffffff, FSL_SAI_FLAGS);
+	regmap_update_bits(sai->regmap, FSL_SAI_RCSR, 0xffffffff, FSL_SAI_FLAGS);
 	regmap_update_bits(sai->regmap, FSL_SAI_TCR1, FSL_SAI_CR1_RFW_MASK,
 			   FSL_SAI_MAXBURST_TX * 2);
 	regmap_update_bits(sai->regmap, FSL_SAI_RCR1, FSL_SAI_CR1_RFW_MASK,
@@ -490,12 +555,14 @@ static int fsl_sai_probe(struct platform_device *pdev)
 	struct fsl_sai *sai;
 	struct resource *res;
 	void __iomem *base;
-	int ret;
+	int irq, ret;
 
 	sai = devm_kzalloc(&pdev->dev, sizeof(*sai), GFP_KERNEL);
 	if (!sai)
 		return -ENOMEM;
 
+	sai->pdev = pdev;
+
 	sai->big_endian_regs = of_property_read_bool(np, "big-endian-regs");
 	if (sai->big_endian_regs)
 		fsl_sai_regmap_config.val_format_endian = REGMAP_ENDIAN_BIG;
@@ -514,6 +581,18 @@ static int fsl_sai_probe(struct platform_device *pdev)
 		return PTR_ERR(sai->regmap);
 	}
 
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "no irq for node %s\n", np->full_name);
+		return irq;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, fsl_sai_isr, 0, np->name, sai);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to claim irq %u\n", irq);
+		return ret;
+	}
+
 	sai->dma_params_rx.addr = res->start + FSL_SAI_RDR;
 	sai->dma_params_tx.addr = res->start + FSL_SAI_TDR;
 	sai->dma_params_rx.maxburst = FSL_SAI_MAXBURST_RX;
diff --git a/sound/soc/fsl/fsl_sai.h b/sound/soc/fsl/fsl_sai.h
index e432260..a264185 100644
--- a/sound/soc/fsl/fsl_sai.h
+++ b/sound/soc/fsl/fsl_sai.h
@@ -37,7 +37,21 @@
 
 /* SAI Transmit/Recieve Control Register */
 #define FSL_SAI_CSR_TERE	BIT(31)
+#define FSL_SAI_CSR_FR		BIT(25)
+#define FSL_SAI_CSR_xF_SHIFT	16
+#define FSL_SAI_CSR_xF_W_SHIFT	18
+#define FSL_SAI_CSR_xF_MASK	(0x1f << FSL_SAI_CSR_xF_SHIFT)
+#define FSL_SAI_CSR_xF_W_MASK	(0x7 << FSL_SAI_CSR_xF_W_SHIFT)
+#define FSL_SAI_CSR_WSF		BIT(20)
+#define FSL_SAI_CSR_SEF		BIT(19)
+#define FSL_SAI_CSR_FEF		BIT(18)
 #define FSL_SAI_CSR_FWF		BIT(17)
+#define FSL_SAI_CSR_FRF		BIT(16)
+#define FSL_SAI_CSR_xIE_SHIFT	8
+#define FSL_SAI_CSR_WSIE	BIT(12)
+#define FSL_SAI_CSR_SEIE	BIT(11)
+#define FSL_SAI_CSR_FEIE	BIT(10)
+#define FSL_SAI_CSR_FWIE	BIT(9)
 #define FSL_SAI_CSR_FRIE	BIT(8)
 #define FSL_SAI_CSR_FRDE	BIT(0)
 
@@ -99,6 +113,7 @@
 #define FSL_SAI_MAXBURST_RX 6
 
 struct fsl_sai {
+	struct platform_device *pdev;
 	struct regmap *regmap;
 
 	bool big_endian_regs;
-- 
1.8.4