I2C bus enters the STOP condition after the DATA_DONE interrupt is raised.
Essentially the driver should be checking the bus state before sending
the next transaction. In case the next transaction is initiated while the
bus is busy, the prior transactions stop condition is not acheived.
Add the check to make sure the bus is not busy before next transaction.
Signed-off-by: George Cherian <george.cherian@xxxxxxxxxx>
---
drivers/i2c/busses/i2c-xlp9xx.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-xlp9xx.c b/drivers/i2c/busses/i2c-xlp9xx.c
index 1f6d780..fa9d5ee 100644
--- a/drivers/i2c/busses/i2c-xlp9xx.c
+++ b/drivers/i2c/busses/i2c-xlp9xx.c
@@ -16,6 +16,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
+#include <linux/delay.h>
#define XLP9XX_I2C_DIV 0x0
#define XLP9XX_I2C_CTRL 0x1
@@ -36,6 +37,8 @@
#define XLP9XX_I2C_TIMEOUT 0X10
#define XLP9XX_I2C_GENCALLADDR 0x11
+#define XLP9XX_I2C_STATUS_BUSY BIT(0)
+
#define XLP9XX_I2C_CMD_START BIT(7)
#define XLP9XX_I2C_CMD_STOP BIT(6)
#define XLP9XX_I2C_CMD_READ BIT(5)
@@ -71,6 +74,7 @@
#define XLP9XX_I2C_HIGH_FREQ 400000
#define XLP9XX_I2C_FIFO_SIZE 0x80U
#define XLP9XX_I2C_TIMEOUT_MS 1000
+#define XLP9XX_I2C_BUSY_TIMEOUT 50
#define XLP9XX_I2C_FIFO_WCNT_MASK 0xff
#define XLP9XX_I2C_STATUS_ERRMASK (XLP9XX_I2C_INTEN_ARLOST | \
@@ -264,7 +268,8 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg,
int last_msg)
{
unsigned long timeleft;
- u32 intr_mask, cmd, val, len;
+ u32 intr_mask, cmd, val, len, status;
+ u32 busy_timeout = XLP9XX_I2C_BUSY_TIMEOUT;
priv->msg_buf = msg->buf;
priv->msg_buf_remaining = priv->msg_len = msg->len;
@@ -351,6 +356,19 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg,
return -ETIMEDOUT;
}
+ while (last_msg && busy_timeout) {
+ status = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_STATUS);
+ if ((status & XLP9XX_I2C_STATUS_BUSY) == 0)
+ break;
+
+ busy_timeout--;
+ udelay(1);
+ }
+
+ if (!busy_timeout) {
+ dev_dbg(priv->dev, "i2c bus busy for too long after transfer\n");
+ return -EIO;
+ }
/* update msg->len with actual received length */
if (msg->flags & I2C_M_RECV_LEN)
msg->len = priv->msg_len;
--
2.1.4
