[PATCH v2 2/6] i2c: qcom-cci: Handle and report queue overflow/underflow interrupts

[Loic Poulain <loic.poulain@oss.qualcomm.com>]

CCI_IRQ_STATUS_0_I2C_Mx_ERROR aggregates the per-queue overflow and
underflow bits together with NACK_ERR, and all of them were
handled the same way: report -EIO and halt the queue. There was no
way to tell a NACK apart from a FIFO overflow/underflow in the logs.

Decode the individual overflow/underflow bits for each queue and
report them with dev_warn_ratelimited() as such errors are not
expected in normal operation.

Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/i2c/busses/i2c-qcom-cci.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-cci.c b/drivers/i2c/busses/i2c-qcom-cci.c
index 3304760411082b72e10e529a2bd66361e100fa06..099da0069251681cc52e351fb656bd73e78a96c9 100644
--- a/drivers/i2c/busses/i2c-qcom-cci.c
+++ b/drivers/i2c/busses/i2c-qcom-cci.c
@@ -54,10 +54,18 @@
 #define CCI_IRQ_STATUS_0			0xc0c
 #define CCI_IRQ_STATUS_0_I2C_M0_RD_DONE		BIT(0)
 #define CCI_IRQ_STATUS_0_I2C_M0_Q0_REPORT	BIT(4)
+#define CCI_IRQ_STATUS_0_I2C_M0_Q0_UNDERFLOW	BIT(5)
+#define CCI_IRQ_STATUS_0_I2C_M0_Q0_OVERFLOW	BIT(6)
 #define CCI_IRQ_STATUS_0_I2C_M0_Q1_REPORT	BIT(8)
+#define CCI_IRQ_STATUS_0_I2C_M0_Q1_UNDERFLOW	BIT(9)
+#define CCI_IRQ_STATUS_0_I2C_M0_Q1_OVERFLOW	BIT(10)
 #define CCI_IRQ_STATUS_0_I2C_M1_RD_DONE		BIT(12)
 #define CCI_IRQ_STATUS_0_I2C_M1_Q0_REPORT	BIT(16)
+#define CCI_IRQ_STATUS_0_I2C_M1_Q0_UNDERFLOW	BIT(17)
+#define CCI_IRQ_STATUS_0_I2C_M1_Q0_OVERFLOW	BIT(18)
 #define CCI_IRQ_STATUS_0_I2C_M1_Q1_REPORT	BIT(20)
+#define CCI_IRQ_STATUS_0_I2C_M1_Q1_UNDERFLOW	BIT(21)
+#define CCI_IRQ_STATUS_0_I2C_M1_Q1_OVERFLOW	BIT(22)
 #define CCI_IRQ_STATUS_0_RST_DONE_ACK		BIT(24)
 #define CCI_IRQ_STATUS_0_I2C_M0_Q0Q1_HALT_ACK	BIT(25)
 #define CCI_IRQ_STATUS_0_I2C_M1_Q0Q1_HALT_ACK	BIT(26)
@@ -190,22 +198,40 @@ static irqreturn_t cci_isr(int irq, void *dev)
 		writel(reset, cci->base + CCI_RESET_CMD);
 
 	if (unlikely(val & CCI_IRQ_STATUS_0_I2C_M0_ERROR)) {
+		cci->master[0].status = -EIO;
+
 		if (val & CCI_IRQ_STATUS_0_I2C_M0_Q0_NACK_ERR ||
 			val & CCI_IRQ_STATUS_0_I2C_M0_Q1_NACK_ERR)
 			cci->master[0].status = -ENXIO;
-		else
-			cci->master[0].status = -EIO;
+
+		if (val & CCI_IRQ_STATUS_0_I2C_M0_Q0_OVERFLOW)
+			dev_warn_ratelimited(cci->dev, "master 0 queue 0 overflow\n");
+		if (val & CCI_IRQ_STATUS_0_I2C_M0_Q0_UNDERFLOW)
+			dev_warn_ratelimited(cci->dev, "master 0 queue 0 underflow\n");
+		if (val & CCI_IRQ_STATUS_0_I2C_M0_Q1_OVERFLOW)
+			dev_warn_ratelimited(cci->dev, "master 0 queue 1 overflow\n");
+		if (val & CCI_IRQ_STATUS_0_I2C_M0_Q1_UNDERFLOW)
+			dev_warn_ratelimited(cci->dev, "master 0 queue 1 underflow\n");
 
 		writel(CCI_HALT_REQ_I2C_M0_Q0Q1, cci->base + CCI_HALT_REQ);
 		ret = IRQ_HANDLED;
 	}
 
 	if (unlikely(val & CCI_IRQ_STATUS_0_I2C_M1_ERROR)) {
+		cci->master[1].status = -EIO;
+
 		if (val & CCI_IRQ_STATUS_0_I2C_M1_Q0_NACK_ERR ||
 			val & CCI_IRQ_STATUS_0_I2C_M1_Q1_NACK_ERR)
 			cci->master[1].status = -ENXIO;
-		else
-			cci->master[1].status = -EIO;
+
+		if (val & CCI_IRQ_STATUS_0_I2C_M1_Q0_OVERFLOW)
+			dev_warn_ratelimited(cci->dev, "master 1 queue 0 overflow\n");
+		if (val & CCI_IRQ_STATUS_0_I2C_M1_Q0_UNDERFLOW)
+			dev_warn_ratelimited(cci->dev, "master 1 queue 0 underflow\n");
+		if (val & CCI_IRQ_STATUS_0_I2C_M1_Q1_OVERFLOW)
+			dev_warn_ratelimited(cci->dev, "master 1 queue 1 overflow\n");
+		if (val & CCI_IRQ_STATUS_0_I2C_M1_Q1_UNDERFLOW)
+			dev_warn_ratelimited(cci->dev, "master 1 queue 1 underflow\n");
 
 		writel(CCI_HALT_REQ_I2C_M1_Q0Q1, cci->base + CCI_HALT_REQ);
 		ret = IRQ_HANDLED;

-- 
2.34.1