[PATCH v2 0/6] fix iproc driver to handle master read request

[PATCH v2 0/6] fix iproc driver to handle master read request

[Rayagonda Kokatanur]

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This series of patches adds the following,
- Handle master abort error
- Fix support for single/multi byte master read request with/without
repeated start.
- Handle rx fifo full interrupt
- Fix typo

Changes from V1:
--Address review comments from Ray Jui,
  Remove fixes tag

Rayagonda Kokatanur (6):
  i2c: iproc: handle Master aborted error
  i2c: iproc: handle only slave interrupts which are enabled
  i2c: iproc: update slave isr mask (ISR_MASK_SLAVE)
  i2c: iproc: fix typo in slave_isr function
  i2c: iproc: handle master read request
  i2c: iproc: handle rx fifo full interrupt

 drivers/i2c/busses/i2c-bcm-iproc.c | 254 +++++++++++++++++++++++------
 1 file changed, 200 insertions(+), 54 deletions(-)

-- 
2.17.1


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[PATCH v2 1/6] i2c: iproc: handle Master aborted error

[Rayagonda Kokatanur]

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Handle Master aborted error by flushing tx and rx fifo
and reinitializing the hw.

Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
---
 drivers/i2c/busses/i2c-bcm-iproc.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index d8295b1c379d..834a98caeada 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -93,6 +93,7 @@
 #define S_CMD_STATUS_MASK            0x07
 #define S_CMD_STATUS_SUCCESS         0x0
 #define S_CMD_STATUS_TIMEOUT         0x5
+#define S_CMD_STATUS_MASTER_ABORT    0x7
 
 #define IE_OFFSET                    0x38
 #define IE_M_RX_FIFO_FULL_SHIFT      31
@@ -311,9 +312,10 @@ static void bcm_iproc_i2c_check_slave_status(
 		return;
 
 	val = (val >> S_CMD_STATUS_SHIFT) & S_CMD_STATUS_MASK;
-	if (val == S_CMD_STATUS_TIMEOUT) {
-		dev_err(iproc_i2c->device, "slave random stretch time timeout\n");
-
+	if (val == S_CMD_STATUS_TIMEOUT || val == S_CMD_STATUS_MASTER_ABORT) {
+		dev_err(iproc_i2c->device, (val == S_CMD_STATUS_TIMEOUT) ?
+			"slave random stretch time timeout\n" :
+			"Master aborted read transaction\n");
 		/* re-initialize i2c for recovery */
 		bcm_iproc_i2c_enable_disable(iproc_i2c, false);
 		bcm_iproc_i2c_slave_init(iproc_i2c, true);
-- 
2.17.1


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[PATCH v2 2/6] i2c: iproc: handle only slave interrupts which are enabled

[Rayagonda Kokatanur]

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Handle only slave interrupts which are enabled.

The IS_OFFSET register contains the interrupt status bits which will be
set regardless of the enabling of the corresponding interrupt condition.
One must therefore look at both IS_OFFSET and IE_OFFSET to determine
whether an interrupt condition is set and enabled.

Fixes: c245d94ed106 ("i2c: iproc: Add multi byte read-write support for slave mode")
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
---
 drivers/i2c/busses/i2c-bcm-iproc.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index 834a98caeada..b54f5130d246 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -507,12 +507,17 @@ static void bcm_iproc_i2c_process_m_event(struct bcm_iproc_i2c_dev *iproc_i2c,
 static irqreturn_t bcm_iproc_i2c_isr(int irq, void *data)
 {
 	struct bcm_iproc_i2c_dev *iproc_i2c = data;
-	u32 status = iproc_i2c_rd_reg(iproc_i2c, IS_OFFSET);
+	u32 slave_status;
+	u32 status;
 	bool ret;
-	u32 sl_status = status & ISR_MASK_SLAVE;
 
-	if (sl_status) {
-		ret = bcm_iproc_i2c_slave_isr(iproc_i2c, sl_status);
+	status = iproc_i2c_rd_reg(iproc_i2c, IS_OFFSET);
+	/* process only slave interrupt which are enabled */
+	slave_status = status & iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET) &
+		       ISR_MASK_SLAVE;
+
+	if (slave_status) {
+		ret = bcm_iproc_i2c_slave_isr(iproc_i2c, slave_status);
 		if (ret)
 			return IRQ_HANDLED;
 		else
-- 
2.17.1


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[PATCH v2 3/6] i2c: iproc: update slave isr mask (ISR_MASK_SLAVE)

[Rayagonda Kokatanur]

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Update slave isr mask (ISR_MASK_SLAVE) to include remaining
two slave interrupts.

Fixes: c245d94ed106 ("i2c: iproc: Add multi byte read-write support for slave mode")
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
---
 drivers/i2c/busses/i2c-bcm-iproc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index b54f5130d246..cd687696bf0b 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -216,7 +216,8 @@ struct bcm_iproc_i2c_dev {
 
 #define ISR_MASK_SLAVE (BIT(IS_S_START_BUSY_SHIFT)\
 		| BIT(IS_S_RX_EVENT_SHIFT) | BIT(IS_S_RD_EVENT_SHIFT)\
-		| BIT(IS_S_TX_UNDERRUN_SHIFT))
+		| BIT(IS_S_TX_UNDERRUN_SHIFT) | BIT(IS_S_RX_FIFO_FULL_SHIFT)\
+		| BIT(IS_S_RX_THLD_SHIFT))
 
 static int bcm_iproc_i2c_reg_slave(struct i2c_client *slave);
 static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave);
-- 
2.17.1


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[PATCH v2 4/6] i2c: iproc: fix typo in slave_isr function

[Rayagonda Kokatanur]

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Fix typo in bcm_iproc_i2c_slave_isr().

Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
---
 drivers/i2c/busses/i2c-bcm-iproc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index cd687696bf0b..7a235f9f5884 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -382,7 +382,7 @@ static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c,
 	if (status & BIT(IS_S_START_BUSY_SHIFT)) {
 		i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, &value);
 		/*
-		 * Enable interrupt for TX FIFO becomes empty and
+		 * Disable interrupt for TX FIFO becomes empty and
 		 * less than PKT_LENGTH bytes were output on the SMBUS
 		 */
 		val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
-- 
2.17.1


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[PATCH v2 5/6] i2c: iproc: handle master read request

[Rayagonda Kokatanur]

[-- Attachment #1.1: Type: text/plain, Size: 10059 bytes --]

Handle single or multi byte master read request with or without
repeated start.

Fixes: c245d94ed106 ("i2c: iproc: Add multi byte read-write support for slave mode")
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
---
 drivers/i2c/busses/i2c-bcm-iproc.c | 215 +++++++++++++++++++++++------
 1 file changed, 170 insertions(+), 45 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index 7a235f9f5884..22e04055b447 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -160,6 +160,11 @@
 
 #define IE_S_ALL_INTERRUPT_SHIFT     21
 #define IE_S_ALL_INTERRUPT_MASK      0x3f
+/*
+ * It takes ~18us to reading 10bytes of data, hence to keep tasklet
+ * running for less time, max slave read per tasklet is set to 10 bytes.
+ */
+#define MAX_SLAVE_RX_PER_INT         10
 
 enum i2c_slave_read_status {
 	I2C_SLAVE_RX_FIFO_EMPTY = 0,
@@ -206,8 +211,18 @@ struct bcm_iproc_i2c_dev {
 	/* bytes that have been read */
 	unsigned int rx_bytes;
 	unsigned int thld_bytes;
+
+	bool slave_rx_only;
+	bool rx_start_rcvd;
+	bool slave_read_complete;
+	u32 tx_underrun;
+	u32 slave_int_mask;
+	struct tasklet_struct slave_rx_tasklet;
 };
 
+/* tasklet to process slave rx data */
+static void slave_rx_tasklet_fn(unsigned long);
+
 /*
  * Can be expanded in the future if more interrupt status bits are utilized
  */
@@ -261,6 +276,7 @@ static void bcm_iproc_i2c_slave_init(
 {
 	u32 val;
 
+	iproc_i2c->tx_underrun = 0;
 	if (need_reset) {
 		/* put controller in reset */
 		val = iproc_i2c_rd_reg(iproc_i2c, CFG_OFFSET);
@@ -297,8 +313,11 @@ static void bcm_iproc_i2c_slave_init(
 
 	/* Enable interrupt register to indicate a valid byte in receive fifo */
 	val = BIT(IE_S_RX_EVENT_SHIFT);
+	/* Enable interrupt register to indicate a Master read transaction */
+	val |= BIT(IE_S_RD_EVENT_SHIFT);
 	/* Enable interrupt register for the Slave BUSY command */
 	val |= BIT(IE_S_START_BUSY_SHIFT);
+	iproc_i2c->slave_int_mask = val;
 	iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
 }
 
@@ -324,76 +343,176 @@ static void bcm_iproc_i2c_check_slave_status(
 	}
 }
 
-static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c,
-				    u32 status)
+static void bcm_iproc_i2c_slave_read(struct bcm_iproc_i2c_dev *iproc_i2c)
 {
+	u8 rx_data, rx_status;
+	u32 rx_bytes = 0;
 	u32 val;
-	u8 value, rx_status;
 
-	/* Slave RX byte receive */
-	if (status & BIT(IS_S_RX_EVENT_SHIFT)) {
+	while (rx_bytes < MAX_SLAVE_RX_PER_INT) {
 		val = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET);
 		rx_status = (val >> S_RX_STATUS_SHIFT) & S_RX_STATUS_MASK;
-		if (rx_status == I2C_SLAVE_RX_START) {
-			/* Start of SMBUS for Master write */
-			i2c_slave_event(iproc_i2c->slave,
-					I2C_SLAVE_WRITE_REQUESTED, &value);
+		rx_data = ((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK);
 
-			val = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET);
-			value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK);
+		if (rx_status == I2C_SLAVE_RX_START) {
+			/* Start of SMBUS Master write */
 			i2c_slave_event(iproc_i2c->slave,
-					I2C_SLAVE_WRITE_RECEIVED, &value);
-		} else if (status & BIT(IS_S_RD_EVENT_SHIFT)) {
-			/* Start of SMBUS for Master Read */
+					I2C_SLAVE_WRITE_REQUESTED, &rx_data);
+			iproc_i2c->rx_start_rcvd = true;
+			iproc_i2c->slave_read_complete = false;
+		} else if (rx_status == I2C_SLAVE_RX_DATA &&
+			   iproc_i2c->rx_start_rcvd) {
+			/* Middle of SMBUS Master write */
 			i2c_slave_event(iproc_i2c->slave,
-					I2C_SLAVE_READ_REQUESTED, &value);
-			iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value);
+					I2C_SLAVE_WRITE_RECEIVED, &rx_data);
+		} else if (rx_status == I2C_SLAVE_RX_END &&
+			   iproc_i2c->rx_start_rcvd) {
+			/* End of SMBUS Master write */
+			if (iproc_i2c->slave_rx_only)
+				i2c_slave_event(iproc_i2c->slave,
+						I2C_SLAVE_WRITE_RECEIVED,
+						&rx_data);
+
+			i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP,
+					&rx_data);
+		} else if (rx_status == I2C_SLAVE_RX_FIFO_EMPTY) {
+			iproc_i2c->rx_start_rcvd = false;
+			iproc_i2c->slave_read_complete = true;
+			break;
+		}
 
-			val = BIT(S_CMD_START_BUSY_SHIFT);
-			iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val);
+		rx_bytes++;
+	}
+}
 
-			/*
-			 * Enable interrupt for TX FIFO becomes empty and
-			 * less than PKT_LENGTH bytes were output on the SMBUS
-			 */
-			val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
-			val |= BIT(IE_S_TX_UNDERRUN_SHIFT);
-			iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
-		} else {
-			/* Master write other than start */
-			value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK);
+static void slave_rx_tasklet_fn(unsigned long data)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = (struct bcm_iproc_i2c_dev *)data;
+	u32 int_clr;
+
+	bcm_iproc_i2c_slave_read(iproc_i2c);
+
+	/* clear pending IS_S_RX_EVENT_SHIFT interrupt */
+	int_clr = BIT(IS_S_RX_EVENT_SHIFT);
+
+	if (!iproc_i2c->slave_rx_only && iproc_i2c->slave_read_complete) {
+		/*
+		 * In case of single byte master-read request,
+		 * IS_S_TX_UNDERRUN_SHIFT event is generated before
+		 * IS_S_START_BUSY_SHIFT event. Hence start slave data send
+		 * from first IS_S_TX_UNDERRUN_SHIFT event.
+		 *
+		 * This means don't send any data from slave when
+		 * IS_S_RD_EVENT_SHIFT event is generated else it will increment
+		 * eeprom or other backend slave driver read pointer twice.
+		 */
+		iproc_i2c->tx_underrun = 0;
+		iproc_i2c->slave_int_mask |= BIT(IE_S_TX_UNDERRUN_SHIFT);
+
+		/* clear IS_S_RD_EVENT_SHIFT interrupt */
+		int_clr |= BIT(IS_S_RD_EVENT_SHIFT);
+	}
+
+	/* clear slave interrupt */
+	iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, int_clr);
+	/* enable slave interrupts */
+	iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, iproc_i2c->slave_int_mask);
+}
+
+static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c,
+				    u32 status)
+{
+	u32 val;
+	u8 value;
+
+	/*
+	 * Slave events in case of master-write, master-write-read and,
+	 * master-read
+	 *
+	 * Master-write     : only IS_S_RX_EVENT_SHIFT event
+	 * Master-write-read: both IS_S_RX_EVENT_SHIFT and IS_S_RD_EVENT_SHIFT
+	 *                    events
+	 * Master-read      : both IS_S_RX_EVENT_SHIFT and IS_S_RD_EVENT_SHIFT
+	 *                    events or only IS_S_RD_EVENT_SHIFT
+	 */
+	if (status & BIT(IS_S_RX_EVENT_SHIFT) ||
+	    status & BIT(IS_S_RD_EVENT_SHIFT)) {
+		/* disable slave interrupts */
+		val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
+		val &= ~iproc_i2c->slave_int_mask;
+		iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
+
+		if (status & BIT(IS_S_RD_EVENT_SHIFT))
+			/* Master-write-read request */
+			iproc_i2c->slave_rx_only = false;
+		else
+			/* Master-write request only */
+			iproc_i2c->slave_rx_only = true;
+
+		/* schedule tasklet to read data later */
+		tasklet_schedule(&iproc_i2c->slave_rx_tasklet);
+
+		/* clear only IS_S_RX_EVENT_SHIFT interrupt */
+		iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET,
+				 BIT(IS_S_RX_EVENT_SHIFT));
+	}
+
+	if (status & BIT(IS_S_TX_UNDERRUN_SHIFT)) {
+		iproc_i2c->tx_underrun++;
+		if (iproc_i2c->tx_underrun == 1)
+			/* Start of SMBUS for Master Read */
 			i2c_slave_event(iproc_i2c->slave,
-					I2C_SLAVE_WRITE_RECEIVED, &value);
-			if (rx_status == I2C_SLAVE_RX_END)
-				i2c_slave_event(iproc_i2c->slave,
-						I2C_SLAVE_STOP, &value);
-		}
-	} else if (status & BIT(IS_S_TX_UNDERRUN_SHIFT)) {
-		/* Master read other than start */
-		i2c_slave_event(iproc_i2c->slave,
-				I2C_SLAVE_READ_PROCESSED, &value);
+					I2C_SLAVE_READ_REQUESTED,
+					&value);
+		else
+			/* Master read other than start */
+			i2c_slave_event(iproc_i2c->slave,
+					I2C_SLAVE_READ_PROCESSED,
+					&value);
 
 		iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value);
+		/* start transfer */
 		val = BIT(S_CMD_START_BUSY_SHIFT);
 		iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val);
+
+		/* clear interrupt */
+		iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET,
+				 BIT(IS_S_TX_UNDERRUN_SHIFT));
 	}
 
-	/* Stop */
+	/* Stop received from master in case of master read transaction */
 	if (status & BIT(IS_S_START_BUSY_SHIFT)) {
-		i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, &value);
 		/*
 		 * Disable interrupt for TX FIFO becomes empty and
 		 * less than PKT_LENGTH bytes were output on the SMBUS
 		 */
-		val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
-		val &= ~BIT(IE_S_TX_UNDERRUN_SHIFT);
-		iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
+		iproc_i2c->slave_int_mask &= ~BIT(IE_S_TX_UNDERRUN_SHIFT);
+		iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET,
+				 iproc_i2c->slave_int_mask);
+
+		/* End of SMBUS for Master Read */
+		val = BIT(S_TX_WR_STATUS_SHIFT);
+		iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, val);
+
+		val = BIT(S_CMD_START_BUSY_SHIFT);
+		iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val);
+
+		/* flush TX FIFOs */
+		val = iproc_i2c_rd_reg(iproc_i2c, S_FIFO_CTRL_OFFSET);
+		val |= (BIT(S_FIFO_TX_FLUSH_SHIFT));
+		iproc_i2c_wr_reg(iproc_i2c, S_FIFO_CTRL_OFFSET, val);
+
+		i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, &value);
+
+		/* clear interrupt */
+		iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET,
+				 BIT(IS_S_START_BUSY_SHIFT));
 	}
 
-	/* clear interrupt status */
-	iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, status);
+	/* check slave transmit status only if slave is transmitting */
+	if (!iproc_i2c->slave_rx_only)
+		bcm_iproc_i2c_check_slave_status(iproc_i2c);
 
-	bcm_iproc_i2c_check_slave_status(iproc_i2c);
 	return true;
 }
 
@@ -1074,6 +1193,10 @@ static int bcm_iproc_i2c_reg_slave(struct i2c_client *slave)
 		return -EAFNOSUPPORT;
 
 	iproc_i2c->slave = slave;
+
+	tasklet_init(&iproc_i2c->slave_rx_tasklet, slave_rx_tasklet_fn,
+		     (unsigned long)iproc_i2c);
+
 	bcm_iproc_i2c_slave_init(iproc_i2c, false);
 	return 0;
 }
@@ -1094,6 +1217,8 @@ static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave)
 			IE_S_ALL_INTERRUPT_SHIFT);
 	iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, tmp);
 
+	tasklet_kill(&iproc_i2c->slave_rx_tasklet);
+
 	/* Erase the slave address programmed */
 	tmp = iproc_i2c_rd_reg(iproc_i2c, S_CFG_SMBUS_ADDR_OFFSET);
 	tmp &= ~BIT(S_CFG_EN_NIC_SMB_ADDR3_SHIFT);
-- 
2.17.1


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[PATCH v2 6/6] i2c: iproc: handle rx fifo full interrupt

[Rayagonda Kokatanur]

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Add code to handle IS_S_RX_FIFO_FULL_SHIFT interrupt to support
master write request with >= 64 bytes.

Iproc has a slave rx fifo size of 64 bytes.
Rx fifo full interrupt (IS_S_RX_FIFO_FULL_SHIFT) will be generated
when RX fifo becomes full. This can happen if master issues write
request of more than 64 bytes.

Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
---
 drivers/i2c/busses/i2c-bcm-iproc.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index 22e04055b447..cceaf69279a9 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -313,6 +313,8 @@ static void bcm_iproc_i2c_slave_init(
 
 	/* Enable interrupt register to indicate a valid byte in receive fifo */
 	val = BIT(IE_S_RX_EVENT_SHIFT);
+	/* Enable interrupt register to indicate Slave Rx FIFO Full */
+	val |= BIT(IE_S_RX_FIFO_FULL_SHIFT);
 	/* Enable interrupt register to indicate a Master read transaction */
 	val |= BIT(IE_S_RD_EVENT_SHIFT);
 	/* Enable interrupt register for the Slave BUSY command */
@@ -434,9 +436,15 @@ static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c,
 	 *                    events
 	 * Master-read      : both IS_S_RX_EVENT_SHIFT and IS_S_RD_EVENT_SHIFT
 	 *                    events or only IS_S_RD_EVENT_SHIFT
+	 *
+	 * iproc has a slave rx fifo size of 64 bytes. Rx fifo full interrupt
+	 * (IS_S_RX_FIFO_FULL_SHIFT) will be generated when RX fifo becomes
+	 * full. This can happen if Master issues write requests of more than
+	 * 64 bytes.
 	 */
 	if (status & BIT(IS_S_RX_EVENT_SHIFT) ||
-	    status & BIT(IS_S_RD_EVENT_SHIFT)) {
+	    status & BIT(IS_S_RD_EVENT_SHIFT) ||
+	    status & BIT(IS_S_RX_FIFO_FULL_SHIFT)) {
 		/* disable slave interrupts */
 		val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
 		val &= ~iproc_i2c->slave_int_mask;
@@ -452,9 +460,14 @@ static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c,
 		/* schedule tasklet to read data later */
 		tasklet_schedule(&iproc_i2c->slave_rx_tasklet);
 
-		/* clear only IS_S_RX_EVENT_SHIFT interrupt */
-		iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET,
-				 BIT(IS_S_RX_EVENT_SHIFT));
+		/*
+		 * clear only IS_S_RX_EVENT_SHIFT and
+		 * IS_S_RX_FIFO_FULL_SHIFT interrupt.
+		 */
+		val = BIT(IS_S_RX_EVENT_SHIFT);
+		if (status & BIT(IS_S_RX_FIFO_FULL_SHIFT))
+			val |= BIT(IS_S_RX_FIFO_FULL_SHIFT);
+		iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, val);
 	}
 
 	if (status & BIT(IS_S_TX_UNDERRUN_SHIFT)) {
-- 
2.17.1


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