[PATCH] i2c: bcm283x: fix ending of transfer in case of NACK

[Daniel Brát]

Fixes an issue where the driver in case of NACK error would not properly
terminate the tranfer, resulting in BSC not sending the STOP condition
until just before the next xfer.

Signed-off-by: Daniel Brát <danek.brat at gmail.com>
---
 drivers/i2c/busses/i2c-bcm283x.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bcm283x.c b/drivers/i2c/busses/i2c-bcm283x.c
index 097f73d983..fdba3b91bd 100644
--- a/drivers/i2c/busses/i2c-bcm283x.c
+++ b/drivers/i2c/busses/i2c-bcm283x.c
@@ -147,7 +147,7 @@ static int bcm283x_i2c_msg_xfer(struct bcm283x_i2c *bcm_i2c,
 
 		if (ret) {
 			dev_err(dev, "timeout: 10bit read initilization\n");
-			return ret;
+			goto out;
 		}
 		if (reg_s & BSC_S_ERR)
 			goto nack;
@@ -178,7 +178,7 @@ static int bcm283x_i2c_msg_xfer(struct bcm283x_i2c *bcm_i2c,
 
 			if (ret) {
 				dev_err(dev, "timeout: waiting for data in FIFO\n");
-				return ret;
+				goto out;
 			}
 			if (reg_s & BSC_S_ERR)
 				goto nack;
@@ -197,7 +197,7 @@ static int bcm283x_i2c_msg_xfer(struct bcm283x_i2c *bcm_i2c,
 
 			if (ret) {
 				dev_err(dev, "timeout: waiting for space in FIFO\n");
-				return ret;
+				goto out;
 			}
 			if (reg_s & BSC_S_ERR)
 				goto nack;
@@ -216,16 +216,23 @@ static int bcm283x_i2c_msg_xfer(struct bcm283x_i2c *bcm_i2c,
 
 	if (ret) {
 		dev_err(dev, "timeout: waiting for transfer to end\n");
-		return ret;
+		goto out;
 	}
 	if (reg_s & BSC_S_ERR)
 		goto nack;
-	writel(BSC_S_DONE | BSC_S_ERR | BSC_S_CLKT, &bcm_i2c->regs->s);
-	writel(BSC_C_CLEAR1 | BSC_C_I2CEN, &bcm_i2c->regs->c);
-	return 0;
+	goto out;
 nack:
 	dev_dbg(dev, "device with addr %x didn't ACK\n", msg->addr);
-	return -EREMOTEIO;
+	writel(BSC_S_ERR, &bcm_i2c->regs->s);
+	timeout = calc_byte_timeout_us(bcm_i2c->bitrate);
+	// Wait for end of transfer so BSC has time to send STOP condition
+	readl_poll_timeout(&bcm_i2c->regs->s, reg_s, ~reg_s & BSC_S_TA, timeout);
+	ret = -EREMOTEIO;
+out:
+	// Return to default state for next xfer
+	writel(BSC_S_DONE | BSC_S_ERR | BSC_S_CLKT, &bcm_i2c->regs->s);
+	writel(BSC_C_CLEAR1 | BSC_C_I2CEN, &bcm_i2c->regs->c);
+	return ret;
 }
 
 static int bcm283x_i2c_xfer(struct i2c_adapter *adapter,
-- 
2.37.0