[PATCH v3 6/6] i2c: iproc: handle rx fifo full interrupt

[Rayagonda Kokatanur]

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.kokata...@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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