soc/amd/mendocino: Add svc_write_postcode call instead of stub

To assist in debugging, add a way for PSP_verstage to send postcodes to
the system.

Signed-off-by: Martin Roth <gaumless@gmail.com>
Change-Id: I22e45e26f599a0b4f0b781e9b97fccb68e2e5cc1
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71852
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/soc/amd/mendocino/psp_verstage/chipset.c

@@ -104,11 +104,6 @@ int platform_set_sha_op(enum vb2_hash_algorithm hash_alg,
  * These functions should be replaced with proper implementations later.
  */
 
-uint32_t svc_write_postcode(uint32_t postcode)
-{
-	return 0;
-}
-
 void platform_report_mode(int developer_mode_enabled)
 {
 	printk(BIOS_INFO, "Reporting %s mode\n",

src/soc/amd/mendocino/psp_verstage/svc.c

@@ -162,6 +162,16 @@ uint32_t svc_reset_system(enum reset_type reset_type)
 	return retval;
 }
 
+uint32_t svc_write_postcode(uint32_t postcode)
+{
+	uint32_t retval = 0;
+	struct cmd_param_postcode param = {
+		.postcode = postcode,
+	};
+	SVC_CALL2(SVC_VERSTAGE_CMD, CMD_WRITE_POSTCODE, (void *)&param, retval);
+	return retval;
+}
+
 uint32_t svc_crypto_sha(struct sha_generic_data *sha_op, enum sha_operation_mode sha_mode)
 {
 	uint32_t retval = 0;

src/soc/amd/mendocino/psp_verstage/svc.h

@@ -102,4 +102,8 @@ struct cmd_param_get_hsp_secure_state {
 	unsigned int hsp_secure_state;
 };
 
+struct cmd_param_postcode {
+	uint32_t postcode;
+};
+
 #endif /* PSP_VERSTAGE_SVC_H */

src/vendorcode/amd/fsp/mendocino/include/bl_uapp/bl_syscall_public.h

@@ -57,6 +57,7 @@ enum verstage_cmd_id {
 	CMD_SET_FW_HASH_TABLE,
 	CMD_GET_PREV_BOOT_STATUS,
 	CMD_GET_HSP_SECURE_STATE,
+	CMD_WRITE_POSTCODE,
 };
 
 struct mod_exp_params {