2 files changed, 47 insertions, 17 deletions

diff --git a/src/soc/intel/common/block/cse/cse.c b/src/soc/intel/common/block/cse/cse.c
index c9712dbb2c..041656a498 100644
--- a/src/soc/intel/common/block/cse/cse.c
+++ b/src/soc/intel/common/block/cse/cse.c
@@ -650,6 +650,26 @@ int cse_request_global_reset(enum rst_req_type rst_type)
 	return status;
 }
 
+static bool cse_is_hmrfpo_enable_allowed(void)
+{
+	/*
+	 * Allow sending HMRFPO ENABLE command only if:
+	 *  - CSE's current working state is Normal and current operation mode is Normal
+	 *  - (or) cse's current working state is normal and current operation mode is
+	 *    Soft Temp Disable if CSE's Firmware SKU is Custom
+	 */
+	if (!cse_is_hfs1_cws_normal())
+		return false;
+
+	if (cse_is_hfs1_com_normal())
+		return true;
+
+	if (cse_is_hfs3_fw_sku_custom() && cse_is_hfs1_com_soft_temp_disable())
+		return true;
+
+	return false;
+}
+
 /* Sends HMRFPO Enable command to CSE */
 int cse_hmrfpo_enable(void)
 {
@@ -675,36 +695,34 @@ int cse_hmrfpo_enable(void)
 		/* Length of factory data area, not relevant for client SKUs */
 		uint32_t fct_limit;
 		uint8_t status;
-		uint8_t padding[3];
+		uint8_t reserved[3];
 	} __packed;
 
 	struct hmrfpo_enable_resp resp;
 	size_t resp_size = sizeof(struct hmrfpo_enable_resp);
 
 	printk(BIOS_DEBUG, "HECI: Send HMRFPO Enable Command\n");
-	/*
-	 * This command can be run only if:
-	 * - Working state is normal and
-	 * - Operation mode is normal or temporary disable mode.
-	 */
-	if (!cse_is_hfs1_cws_normal() ||
-		(!cse_is_hfs1_com_normal() && !cse_is_hfs1_com_soft_temp_disable())) {
-		printk(BIOS_ERR, "HECI: ME not in required Mode\n");
-		goto failed;
+
+	if (!cse_is_hmrfpo_enable_allowed()) {
+		printk(BIOS_ERR, "HECI: CSE does not meet required prerequisites\n");
+		return 0;
 	}
 
 	if (!heci_send_receive(&msg, sizeof(struct hmrfpo_enable_msg),
 				&resp, &resp_size))
-		goto failed;
+		return 0;
 
 	if (resp.hdr.result) {
 		printk(BIOS_ERR, "HECI: Resp Failed:%d\n", resp.hdr.result);
-		goto failed;
+		return 0;
 	}
-	return 1;
 
-failed:
-	return 0;
+	if (resp.status) {
+		printk(BIOS_ERR, "HECI: HMRFPO_Enable Failed (resp status: %d)\n", resp.status);
+		return 0;
+	}
+
+	return 1;
 }
 
 /*
diff --git a/src/soc/intel/common/block/include/intelblocks/cse.h b/src/soc/intel/common/block/include/intelblocks/cse.h
index 93d1ce1d04..595c7d8d6b 100644
--- a/src/soc/intel/common/block/include/intelblocks/cse.h
+++ b/src/soc/intel/common/block/include/intelblocks/cse.h
@@ -136,8 +136,20 @@ enum rst_req_type {
 int cse_request_global_reset(enum rst_req_type rst_type);
 
 /*
- * Send HMRFPO_ENABLE command.
- * returns 0 on failure and 1 on success.
+ * Sends HMRFPO_ENABLE command.
+ * HMRFPO - Host ME Region Flash Protection Override.
+ * For CSE Firmware SKU Custom, procedure to place CSE in HMRFPO (SECOVER_MEI_MSG) mode:
+ *	1. Ensure CSE boots from BP1(RO).
+ *		- Send set_next_boot_partition(BP1)
+ *		- Issue CSE Only Reset
+ *	2. Send HMRFPO_ENABLE command to CSE. Further, no reset is required.
+ *
+ * The HMRFPO mode prevents CSE to execute SPI I/O cycles to CSE region, and unlocks
+ * the CSE region to perform updates to it.
+ * This command is only valid before EOP.
+ *
+ * Returns 0 on failure to send HECI command and to enable HMRFPO mode, and 1 on success.
+ *
  */
 int cse_hmrfpo_enable(void);