[U-Boot] [PATCH 24/41] imx: lpi2c: fix clock issue when NACK detected

[Peng Fan]

From: Gao Pan <pandy.gao at nxp.com>

For LPI2C IP, NACK is detected by the rising edge of the ninth clock.
In current uboot driver, once NACK is detected, it will reset and then
disable LPI2C master. As a result, we can never see the falling edge
of the ninth clock.

Signed-off-by: Gao Pan <pandy.gao at nxp.com>
Signed-off-by: Peng Fan <peng.fan at nxp.com>
Cc: Heiko Schocher <hs at denx.de>
---
 drivers/i2c/imx_lpi2c.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/imx_lpi2c.c b/drivers/i2c/imx_lpi2c.c
index a6e41c5c91..d2e11b411b 100644
--- a/drivers/i2c/imx_lpi2c.c
+++ b/drivers/i2c/imx_lpi2c.c
@@ -15,6 +15,7 @@
 #include <i2c.h>
 
 #define LPI2C_FIFO_SIZE 4
+#define LPI2C_NACK_TOUT_MS 1
 #define LPI2C_TIMEOUT_MS 100
 
 /* Weak linked function for overridden by some SoC power function */
@@ -184,6 +185,7 @@ static int bus_i2c_stop(struct imx_lpi2c_reg *regs)
 {
 	lpi2c_status_t result;
 	u32 status;
+	ulong start_time;
 
 	result = bus_i2c_wait_for_tx_ready(regs);
 	if (result) {
@@ -194,7 +196,8 @@ static int bus_i2c_stop(struct imx_lpi2c_reg *regs)
 	/* send stop command */
 	writel(LPI2C_MTDR_CMD(0x2), &regs->mtdr);
 
-	while (result == LPI2C_SUCESS) {
+	start_time = get_timer(0);
+	while (1) {
 		status = readl(&regs->msr);
 		result = imx_lpci2c_check_clear_error(regs);
 		/* stop detect flag */
@@ -204,6 +207,11 @@ static int bus_i2c_stop(struct imx_lpi2c_reg *regs)
 			writel(status, &regs->msr);
 			break;
 		}
+
+		if (get_timer(start_time) > LPI2C_NACK_TOUT_MS) {
+			debug("stop timeout\n");
+			return -ETIMEDOUT;
+		}
 	}
 
 	return result;
@@ -363,10 +371,8 @@ static int imx_lpi2c_probe_chip(struct udevice *bus, u32 chip,
 	}
 
 	result = bus_i2c_stop(regs);
-	if (result) {
+	if (result)
 		bus_i2c_init(bus, 100000);
-		return -result;
-	}
 
 	return result;
 }
-- 
2.14.1