Change in flashrom[master]: realtek_mst_i2c_spi.c: Introduce ISP enter param

[Shiyu Sun (Code Review)]

Shiyu Sun has uploaded this change for review. ( https://review.coreboot.org/c/flashrom/+/46623 )

Change subject: realtek_mst_i2c_spi.c: Introduce ISP enter param
......................................................................

realtek_mst_i2c_spi.c: Introduce ISP enter param

This is needed to avoid attempt entering ISP mode multiple
times. The ISP mode can only exit after a reset, so once the
reset MCU parameter is set to 0, the device will not able to
exit from ISP mode and hence shouldn't enter ISP again on
the next operation.
Without exit ISP mode, the device data, like firmware version,
will not show the correct value, this param will also help
to identify this situation.

Example on update a firmware with A/B udpate:
flashrom -p realtek_mst_i2c_spi:bus=x,reset-mcu=0,enter-isp=1 write fw
flashrom -p realtek_mst_i2c_spi:bus=x,reset-mcu=0,enter-isp=0 write flag
-> then either reset computer to allow update to take effect, or:
flashrom -p realtek_mst_i2c_spi:bus=x,reset-mcu=1,enter-isp=0 command
to trigger the update.

BUG=b:152558985,b:148745673
BRANCH=none
TEST=build

Signed-off-by: Shiyu Sun 
Change-Id: I58931ac8b42ab55829f102d243aea6fcfd632e3e
---
M realtek_mst_i2c_spi.c
1 file changed, 24 insertions(+), 8 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/23/46623/1

diff --git a/realtek_mst_i2c_spi.c b/realtek_mst_i2c_spi.c
index 43cf25b..538b07a 100644
--- a/realtek_mst_i2c_spi.c
+++ b/realtek_mst_i2c_spi.c
@@ -432,10 +432,10 @@
    return ret;
 }

-static int get_params(int *i2c_bus, int *reset)
+static int get_params(int *i2c_bus, int *reset, int *enter_isp)
 {
-	char *bus_str = NULL, *reset_str = NULL;
-        int ret = SPI_GENERIC_ERROR;
+	char *bus_str = NULL, *reset_str = NULL, *isp_str = NULL;
+	int ret = SPI_GENERIC_ERROR;

bus_str = extract_programmer_param("bus");
    if (bus_str) {
@@ -478,6 +478,20 @@
    	*reset = 0; /* Default behaviour is no MCU reset on tear-down. */
    free(reset_str);

+	isp_str = extract_programmer_param("enter-isp");
+	if (isp_str) {
+		if (isp_str[0] == '1')
+			*enter_isp = 1;
+		else if (isp_str[0] == '0')
+			*enter_isp = 0;
+		else {
+			msg_perr("%s: Incorrect param format, enter-isp=1 or 0.\n", __func__);
+			ret = SPI_GENERIC_ERROR;
+		}
+	} else
+		*enter_isp = 1; /* Default behaviour is enter ISP on setup. */
+	free(isp_str);
+
 _get_params_failed:
    if (bus_str)
    	free(bus_str);
@@ -488,18 +502,20 @@
 int realtek_mst_i2c_spi_init(void)
 {
    int ret = 0;
-	int i2c_bus = 0, reset = 0;
+	int i2c_bus = 0, reset = 0, enter_isp = 0;

-	if (get_params(&i2c_bus, &reset))
+	if (get_params(&i2c_bus, &reset, &enter_isp))
    	return SPI_GENERIC_ERROR;

int fd = i2c_open(i2c_bus, REGISTER_ADDRESS, 0);
    if (fd < 0)
    	return fd;

-	ret |= realtek_mst_i2c_spi_enter_isp_mode(fd);
-	if (ret)
-		return ret;
+	if (enter_isp) {
+		ret |= realtek_mst_i2c_spi_enter_isp_mode(fd);
+		if (ret)
+			return ret;
+	}

struct realtek_mst_i2c_spi_data *data = calloc(1, sizeof(struct realtek_mst_i2c_spi_data));
    if (!data) {