exynos5420: i2c: Fix error handling.

The functions which checked the status of a transfer would return success if
the bus was no longer occupied, even if it's no longer occupied because the
transfer failed. This change modifies those functions to return three possible
values, 0 if the transfer isn't done, -1 if there was a fault, and 1 if the
transaction completed successfully.

Change-Id: Idcc5fdf73cab3c3ece0e96f14113a216db289e05
Signed-off-by: Gabe Black <gabeblack@chromium.org>
Reviewed-on: http://review.coreboot.org/3704
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 36 insertions, 19 deletions

diff --git a/src/cpu/samsung/exynos5420/i2c.c b/src/cpu/samsung/exynos5420/i2c.c
index b16d068c5c..acb5bcf7cc 100644
--- a/src/cpu/samsung/exynos5420/i2c.c
+++ b/src/cpu/samsung/exynos5420/i2c.c
@@ -357,23 +357,39 @@ void i2c_init(unsigned bus_num, int speed, int slaveadd)
 
 /*
  * Check whether the transfer is complete.
+ * Return values:
+ * 0  - transfer not done
+ * 1  - transfer finished successfully
+ * -1 - transfer failed
  */
 static int hsi2c_check_transfer(struct exynos5_hsi2c *i2c)
 {
 	uint32_t status = read32(&i2c->usi_trans_status);
-	if (status & HSI2C_TRANS_ABORT)
-		printk(BIOS_ERR, "%s: Transaction aborted.\n", __func__);
-	if (status & HSI2C_NO_DEV_ACK)
-		printk(BIOS_ERR, "%s: No ack from device.\n", __func__);
-	if (status & HSI2C_NO_DEV)
-		printk(BIOS_ERR, "%s: No response from device.\n", __func__);
-	if (status & HSI2C_TIMEOUT_AUTO)
-		printk(BIOS_ERR, "%s: Transaction time out.\n", __func__);
-	return !!(status & HSI2C_MASTER_BUSY);
+	if (status & (HSI2C_TRANS_ABORT | HSI2C_NO_DEV_ACK |
+		      HSI2C_NO_DEV | HSI2C_TIMEOUT_AUTO)) {
+		if (status & HSI2C_TRANS_ABORT)
+			printk(BIOS_ERR,
+			       "%s: Transaction aborted.\n", __func__);
+		if (status & HSI2C_NO_DEV_ACK)
+			printk(BIOS_ERR,
+			       "%s: No ack from device.\n", __func__);
+		if (status & HSI2C_NO_DEV)
+			printk(BIOS_ERR,
+			       "%s: No response from device.\n", __func__);
+		if (status & HSI2C_TIMEOUT_AUTO)
+			printk(BIOS_ERR,
+			       "%s: Transaction time out.\n", __func__);
+		return -1;
+	}
+	return !(status & HSI2C_MASTER_BUSY);
 }
 
 /*
  * Wait for the transfer to finish.
+ * Return values:
+ * 0  - transfer not done
+ * 1  - transfer finished successfully
+ * -1 - transfer failed
  */
 static int hsi2c_wait_for_transfer(struct exynos5_hsi2c *i2c)
 {
@@ -383,17 +399,18 @@ static int hsi2c_wait_for_transfer(struct exynos5_hsi2c *i2c)
 	end = current;
 	mono_time_add_usecs(&end, HSI2C_TIMEOUT * 1000);
 	while (mono_time_before(&current, &end)) {
-		if (!hsi2c_check_transfer(i2c))
-			return 0;
+		int ret = hsi2c_check_transfer(i2c);
+		if (ret)
+			return ret;
 		udelay(5);
 		timer_monotonic_get(&current);
 	}
-	return 1;
+	return 0;
 }
 
 static int hsi2c_senddata(struct exynos5_hsi2c *i2c, uint8_t *data, int len)
 {
-	while (hsi2c_check_transfer(i2c) && len) {
+	while (!hsi2c_check_transfer(i2c) && len) {
 		if (!(read32(&i2c->usi_fifo_stat) & HSI2C_TX_FIFO_FULL)) {
 			write32(*data++, &i2c->usi_txdata);
 			len--;
@@ -404,7 +421,7 @@ static int hsi2c_senddata(struct exynos5_hsi2c *i2c, uint8_t *data, int len)
 
 static int hsi2c_recvdata(struct exynos5_hsi2c *i2c, uint8_t *data, int len)
 {
-	while (hsi2c_check_transfer(i2c) && len) {
+	while (!hsi2c_check_transfer(i2c) && len) {
 		if (!(read32(&i2c->usi_fifo_stat) & HSI2C_RX_FIFO_EMPTY)) {
 			*data++ = read32(&i2c->usi_rxdata);
 			len--;
@@ -422,7 +439,7 @@ static int hsi2c_write(struct exynos5_hsi2c *i2c,
 {
 	uint32_t i2c_auto_conf;
 
-	if (hsi2c_wait_for_transfer(i2c))
+	if (hsi2c_wait_for_transfer(i2c) != 1)
 		return -1;
 
 	/* chip address */
@@ -441,7 +458,7 @@ static int hsi2c_write(struct exynos5_hsi2c *i2c,
 
 	if (hsi2c_senddata(i2c, addr, alen) ||
 	    hsi2c_senddata(i2c, data, len) ||
-	    hsi2c_wait_for_transfer(i2c)) {
+	    hsi2c_wait_for_transfer(i2c) != 1) {
 		return -1;
 	}
 
@@ -460,7 +477,7 @@ static int hsi2c_read(struct exynos5_hsi2c *i2c,
 	uint32_t i2c_auto_conf;
 
 	/* start read */
-	if (hsi2c_wait_for_transfer(i2c))
+	if (hsi2c_wait_for_transfer(i2c) != 1)
 		return -1;
 
 	/* chip address */
@@ -475,7 +492,7 @@ static int hsi2c_read(struct exynos5_hsi2c *i2c,
 		&i2c->usi_auto_conf);
 
 	if (hsi2c_senddata(i2c, addr, alen) ||
-	    hsi2c_wait_for_transfer(i2c)) {
+	    hsi2c_wait_for_transfer(i2c) != 1) {
 		return -1;
 	}
 
@@ -490,7 +507,7 @@ static int hsi2c_read(struct exynos5_hsi2c *i2c,
 	write32(i2c_auto_conf, &i2c->usi_auto_conf);
 
 	if (hsi2c_recvdata(i2c, data, len) ||
-	    hsi2c_wait_for_transfer(i2c)) {
+	    hsi2c_wait_for_transfer(i2c) != 1) {
 		return -1;
 	}