1 files changed, 124 insertions, 53 deletions

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index 0419f5284609..b9f0fff4e723 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -58,11 +58,13 @@
 #define IE_M_RX_FIFO_FULL_SHIFT      31
 #define IE_M_RX_THLD_SHIFT           30
 #define IE_M_START_BUSY_SHIFT        28
+#define IE_M_TX_UNDERRUN_SHIFT       27
 
 #define IS_OFFSET                    0x3c
 #define IS_M_RX_FIFO_FULL_SHIFT      31
 #define IS_M_RX_THLD_SHIFT           30
 #define IS_M_START_BUSY_SHIFT        28
+#define IS_M_TX_UNDERRUN_SHIFT       27
 
 #define M_TX_OFFSET                  0x40
 #define M_TX_WR_STATUS_SHIFT         31
@@ -76,7 +78,7 @@
 #define M_RX_DATA_SHIFT              0
 #define M_RX_DATA_MASK               0xff
 
-#define I2C_TIMEOUT_MESC             100
+#define I2C_TIMEOUT_MSEC             50000
 #define M_TX_RX_FIFO_SIZE            64
 
 enum bus_speed_index {
@@ -95,12 +97,17 @@ struct bcm_iproc_i2c_dev {
 
 	struct completion done;
 	int xfer_is_done;
+
+	struct i2c_msg *msg;
+
+	/* bytes that have been transferred */
+	unsigned int tx_bytes;
 };
 
 /*
  * Can be expanded in the future if more interrupt status bits are utilized
  */
-#define ISR_MASK (1 << IS_M_START_BUSY_SHIFT)
+#define ISR_MASK (BIT(IS_M_START_BUSY_SHIFT) | BIT(IS_M_TX_UNDERRUN_SHIFT))
 
 static irqreturn_t bcm_iproc_i2c_isr(int irq, void *data)
 {
@@ -112,13 +119,95 @@ static irqreturn_t bcm_iproc_i2c_isr(int irq, void *data)
 	if (!status)
 		return IRQ_NONE;
 
+	/* TX FIFO is empty and we have more data to send */
+	if (status & BIT(IS_M_TX_UNDERRUN_SHIFT)) {
+		struct i2c_msg *msg = iproc_i2c->msg;
+		unsigned int tx_bytes = msg->len - iproc_i2c->tx_bytes;
+		unsigned int i;
+		u32 val;
+
+		/* can only fill up to the FIFO size */
+		tx_bytes = min_t(unsigned int, tx_bytes, M_TX_RX_FIFO_SIZE);
+		for (i = 0; i < tx_bytes; i++) {
+			/* start from where we left over */
+			unsigned int idx = iproc_i2c->tx_bytes + i;
+
+			val = msg->buf[idx];
+
+			/* mark the last byte */
+			if (idx == msg->len - 1) {
+				u32 tmp;
+
+				val |= BIT(M_TX_WR_STATUS_SHIFT);
+
+				/*
+				 * Since this is the last byte, we should
+				 * now disable TX FIFO underrun interrupt
+				 */
+				tmp = readl(iproc_i2c->base + IE_OFFSET);
+				tmp &= ~BIT(IE_M_TX_UNDERRUN_SHIFT);
+				writel(tmp, iproc_i2c->base + IE_OFFSET);
+			}
+
+			/* load data into TX FIFO */
+			writel(val, iproc_i2c->base + M_TX_OFFSET);
+		}
+		/* update number of transferred bytes */
+		iproc_i2c->tx_bytes += tx_bytes;
+	}
+
+	if (status & BIT(IS_M_START_BUSY_SHIFT)) {
+		iproc_i2c->xfer_is_done = 1;
+		complete_all(&iproc_i2c->done);
+	}
+
 	writel(status, iproc_i2c->base + IS_OFFSET);
-	iproc_i2c->xfer_is_done = 1;
-	complete_all(&iproc_i2c->done);
 
 	return IRQ_HANDLED;
 }
 
+static int bcm_iproc_i2c_init(struct bcm_iproc_i2c_dev *iproc_i2c)
+{
+	u32 val;
+
+	/* put controller in reset */
+	val = readl(iproc_i2c->base + CFG_OFFSET);
+	val |= 1 << CFG_RESET_SHIFT;
+	val &= ~(1 << CFG_EN_SHIFT);
+	writel(val, iproc_i2c->base + CFG_OFFSET);
+
+	/* wait 100 usec per spec */
+	udelay(100);
+
+	/* bring controller out of reset */
+	val &= ~(1 << CFG_RESET_SHIFT);
+	writel(val, iproc_i2c->base + CFG_OFFSET);
+
+	/* flush TX/RX FIFOs and set RX FIFO threshold to zero */
+	val = (1 << M_FIFO_RX_FLUSH_SHIFT) | (1 << M_FIFO_TX_FLUSH_SHIFT);
+	writel(val, iproc_i2c->base + M_FIFO_CTRL_OFFSET);
+	/* disable all interrupts */
+	writel(0, iproc_i2c->base + IE_OFFSET);
+
+	/* clear all pending interrupts */
+	writel(0xffffffff, iproc_i2c->base + IS_OFFSET);
+
+	return 0;
+}
+
+static void bcm_iproc_i2c_enable_disable(struct bcm_iproc_i2c_dev *iproc_i2c,
+					 bool enable)
+{
+	u32 val;
+
+	val = readl(iproc_i2c->base + CFG_OFFSET);
+	if (enable)
+		val |= BIT(CFG_EN_SHIFT);
+	else
+		val &= ~BIT(CFG_EN_SHIFT);
+	writel(val, iproc_i2c->base + CFG_OFFSET);
+}
+
 static int bcm_iproc_i2c_check_status(struct bcm_iproc_i2c_dev *iproc_i2c,
 				      struct i2c_msg *msg)
 {
@@ -149,6 +238,12 @@ static int bcm_iproc_i2c_check_status(struct bcm_iproc_i2c_dev *iproc_i2c,
 
 	default:
 		dev_dbg(iproc_i2c->device, "unknown error code=%d\n", val);
+
+		/* re-initialize i2c for recovery */
+		bcm_iproc_i2c_enable_disable(iproc_i2c, false);
+		bcm_iproc_i2c_init(iproc_i2c);
+		bcm_iproc_i2c_enable_disable(iproc_i2c, true);
+
 		return -EIO;
 	}
 }
@@ -159,7 +254,8 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
 	int ret, i;
 	u8 addr;
 	u32 val;
-	unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT_MESC);
+	unsigned int tx_bytes;
+	unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT_MSEC);
 
 	/* check if bus is busy */
 	if (!!(readl(iproc_i2c->base + M_CMD_OFFSET) &
@@ -168,13 +264,20 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
 		return -EBUSY;
 	}
 
+	iproc_i2c->msg = msg;
+
 	/* format and load slave address into the TX FIFO */
 	addr = msg->addr << 1 | (msg->flags & I2C_M_RD ? 1 : 0);
 	writel(addr, iproc_i2c->base + M_TX_OFFSET);
 
-	/* for a write transaction, load data into the TX FIFO */
+	/*
+	 * For a write transaction, load data into the TX FIFO. Only allow
+	 * loading up to TX FIFO size - 1 bytes of data since the first byte
+	 * has been used up by the slave address
+	 */
+	tx_bytes = min_t(unsigned int, msg->len, M_TX_RX_FIFO_SIZE - 1);
 	if (!(msg->flags & I2C_M_RD)) {
-		for (i = 0; i < msg->len; i++) {
+		for (i = 0; i < tx_bytes; i++) {
 			val = msg->buf[i];
 
 			/* mark the last byte */
@@ -183,6 +286,7 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
 
 			writel(val, iproc_i2c->base + M_TX_OFFSET);
 		}
+		iproc_i2c->tx_bytes = tx_bytes;
 	}
 
 	/* mark as incomplete before starting the transaction */
@@ -194,13 +298,24 @@ static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
 	 * transaction is done, i.e., the internal start_busy bit, transitions
 	 * from 1 to 0.
 	 */
-	writel(1 << IE_M_START_BUSY_SHIFT, iproc_i2c->base + IE_OFFSET);
+	val = BIT(IE_M_START_BUSY_SHIFT);
+
+	/*
+	 * If TX data size is larger than the TX FIFO, need to enable TX
+	 * underrun interrupt, which will be triggerred when the TX FIFO is
+	 * empty. When that happens we can then pump more data into the FIFO
+	 */
+	if (!(msg->flags & I2C_M_RD) &&
+	    msg->len > iproc_i2c->tx_bytes)
+		val |= BIT(IE_M_TX_UNDERRUN_SHIFT);
+
+	writel(val, iproc_i2c->base + IE_OFFSET);
 
 	/*
 	 * Now we can activate the transfer. For a read operation, specify the
 	 * number of bytes to read
 	 */
-	val = 1 << M_CMD_START_BUSY_SHIFT;
+	val = BIT(M_CMD_START_BUSY_SHIFT);
 	if (msg->flags & I2C_M_RD) {
 		val |= (M_CMD_PROTOCOL_BLK_RD << M_CMD_PROTOCOL_SHIFT) |
 		       (msg->len << M_CMD_RD_CNT_SHIFT);
@@ -283,7 +398,6 @@ static const struct i2c_algorithm bcm_iproc_algo = {
 static struct i2c_adapter_quirks bcm_iproc_i2c_quirks = {
 	/* need to reserve one byte in the FIFO for the slave address */
 	.max_read_len = M_TX_RX_FIFO_SIZE - 1,
-	.max_write_len = M_TX_RX_FIFO_SIZE - 1,
 };
 
 static int bcm_iproc_i2c_cfg_speed(struct bcm_iproc_i2c_dev *iproc_i2c)
@@ -321,49 +435,6 @@ static int bcm_iproc_i2c_cfg_speed(struct bcm_iproc_i2c_dev *iproc_i2c)
 	return 0;
 }
 
-static int bcm_iproc_i2c_init(struct bcm_iproc_i2c_dev *iproc_i2c)
-{
-	u32 val;
-
-	/* put controller in reset */
-	val = readl(iproc_i2c->base + CFG_OFFSET);
-	val |= 1 << CFG_RESET_SHIFT;
-	val &= ~(1 << CFG_EN_SHIFT);
-	writel(val, iproc_i2c->base + CFG_OFFSET);
-
-	/* wait 100 usec per spec */
-	udelay(100);
-
-	/* bring controller out of reset */
-	val &= ~(1 << CFG_RESET_SHIFT);
-	writel(val, iproc_i2c->base + CFG_OFFSET);
-
-	/* flush TX/RX FIFOs and set RX FIFO threshold to zero */
-	val = (1 << M_FIFO_RX_FLUSH_SHIFT) | (1 << M_FIFO_TX_FLUSH_SHIFT);
-	writel(val, iproc_i2c->base + M_FIFO_CTRL_OFFSET);
-
-	/* disable all interrupts */
-	writel(0, iproc_i2c->base + IE_OFFSET);
-
-	/* clear all pending interrupts */
-	writel(0xffffffff, iproc_i2c->base + IS_OFFSET);
-
-	return 0;
-}
-
-static void bcm_iproc_i2c_enable_disable(struct bcm_iproc_i2c_dev *iproc_i2c,
-					 bool enable)
-{
-	u32 val;
-
-	val = readl(iproc_i2c->base + CFG_OFFSET);
-	if (enable)
-		val |= BIT(CFG_EN_SHIFT);
-	else
-		val &= ~BIT(CFG_EN_SHIFT);
-	writel(val, iproc_i2c->base + CFG_OFFSET);
-}
-
 static int bcm_iproc_i2c_probe(struct platform_device *pdev)
 {
 	int irq, ret = 0;