[coreboot-gerrit] Change in coreboot[master]: soc/intel/common: Retry MEI CSE DISABLE command

[Sridhar Siricilla (Code Review)]

Sridhar Siricilla has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/62560 )

Change subject: soc/intel/common: Retry MEI CSE DISABLE command
......................................................................

soc/intel/common: Retry MEI CSE DISABLE command

The patch retries MEI CSE DISABLE command if cse doesn't respond or
sends the garbled response. It retries the command additionally 2 more
times.

TEST=build and boot the Brya board
Signed-off-by: Sridhar Siricilla 
Change-Id: Id38a172d670a0cd44643744f27b85ca7e368ccdb
---
M src/soc/intel/common/block/cse/cse_eop.c
1 file changed, 44 insertions(+), 7 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/60/62560/1

diff --git a/src/soc/intel/common/block/cse/cse_eop.c b/src/soc/intel/common/block/cse/cse_eop.c
index 5faf21b..1ddca2b 100644
--- a/src/soc/intel/common/block/cse/cse_eop.c
+++ b/src/soc/intel/common/block/cse/cse_eop.c
@@ -11,7 +11,8 @@
 #include <timestamp.h>
 #include <types.h>

-#define MAX_RETRY_EOP_MSG	3
+#define MAX_RETRY_EOP_MSG		3
+#define MAX_RETRY_CSE_DISABLE_MSG	3

enum cse_eop_result {
    CSE_EOP_RESULT_GLOBAL_RESET_REQUESTED,
@@ -21,7 +22,26 @@
    CSE_EOP_RESULT_RETRY,
 };

-static bool cse_disable_mei_bus(void)
+enum cse_cmd_result {
+	CSE_CMD_RESULT_SUCCESS,
+	CSE_CMD_RESULT_ERROR,
+	CSE_CMD_RESULT_RETRY,
+};
+
+static enum cse_cmd_result decode_heci_send_receive_error(enum cse_tx_rx_status ret)
+{
+	switch (ret) {
+	case CSE_TX_ERR_CSE_NOT_READY:
+	case CSE_RX_ERR_CSE_NOT_READY:
+	case CSE_RX_ERR_RESP_LEN_MISMATCH:
+	case CSE_RX_ERR_TIMEOUT:
+		return CSE_CMD_RESULT_RETRY;
+	default:
+		return CSE_CMD_RESULT_ERROR;
+	}
+}
+
+static enum cse_cmd_result cse_disable_mei_bus(void)
 {
    struct bus_disable_message {
    	uint8_t command;
@@ -36,18 +56,35 @@
    } __packed reply = {};

size_t reply_sz = sizeof(reply);
+	enum cse_tx_rx_status ret;

-	if (heci_send_receive(&msg, sizeof(msg), &reply, &reply_sz, HECI_MEI_ADDR)) {
+	printk(BIOS_DEBUG, "HECI, Sending MEI BIOS DISABLE command\n");
+	ret = heci_send_receive(&msg, sizeof(msg), &reply, &reply_sz, HECI_MEI_ADDR);
+
+	if (ret) {
    	printk(BIOS_ERR, "HECI: Failed to Disable MEI bus\n");
-		return false;
+		return decode_heci_send_receive_error(ret);
    }

if (reply.status) {
    	printk(BIOS_ERR, "HECI: MEI_Bus_Disable Failed (status: %d)\n", reply.status);
-		return false;
+		return CSE_CMD_RESULT_ERROR;
    }

-	return true;
+	return CSE_CMD_RESULT_SUCCESS;
+}
+
+static enum cse_cmd_result cse_send_bus_disable_message(void)
+{
+	size_t retry;
+	enum cse_cmd_result ret;
+
+	for (retry = 0; retry < MAX_RETRY_CSE_DISABLE_MSG; retry++) {
+		ret = cse_disable_mei_bus();
+		if (ret != CSE_CMD_RESULT_RETRY)
+			break;
+	}
+	return ret;
 }

static enum cse_eop_result decode_eop_error(enum cse_tx_rx_status ret)
@@ -158,7 +195,7 @@
  */
 static void cse_handle_eop_error(void)
 {
-	if (!cse_disable_mei_bus())
+	if (cse_send_bus_disable_message())
    	die("Failed to disable MEI bus while recovering from EOP error\n"
    	    "Preventing system from booting into an insecure state.\n");