1 files changed, 29 insertions, 7 deletions

diff --git a/platforms/astbmc/common.c b/platforms/astbmc/common.c
index 210b3ec..bc0e58f 100644
--- a/platforms/astbmc/common.c
+++ b/platforms/astbmc/common.c
@@ -208,8 +208,15 @@ static void astbmc_fixup_dt_mbox(struct dt_node *lpc)
 	struct dt_node *mbox;
 	char namebuf[32];
 
-	/* All P9 machines use mbox. P8 machines can indicate they support
-	 * it using the scratch register */
+	if (!lpc)
+		return;
+
+	/*
+	 * P9 machines always use hiomap, either by ipmi or mbox. P8 machines
+	 * can indicate they support mbox using the scratch register, or ipmi
+	 * by configuring the hiomap ipmi command. If neither are configured
+	 * for P8 then skiboot will drive the flash controller directly.
+	 */
 	if (proc_gen != proc_gen_p9 && !ast_scratch_reg_is_mbox())
 		return;
 
@@ -310,7 +317,7 @@ static void astbmc_fixup_bmc_sensors(void)
 	}
 }
 
-static void astbmc_fixup_dt(void)
+static struct dt_node *dt_find_primary_lpc(void)
 {
 	struct dt_node *n, *primary_lpc = NULL;
 
@@ -328,6 +335,15 @@ static void astbmc_fixup_dt(void)
 			break;
 	}
 
+	return primary_lpc;
+}
+
+static void astbmc_fixup_dt(void)
+{
+	struct dt_node *primary_lpc;
+
+	primary_lpc = dt_find_primary_lpc();
+
 	if (!primary_lpc)
 		return;
 
@@ -337,9 +353,6 @@ static void astbmc_fixup_dt(void)
 	/* BT is not in HB either */
 	astbmc_fixup_dt_bt(primary_lpc);
 
-	/* MBOX is not in HB */
-	astbmc_fixup_dt_mbox(primary_lpc);
-
 	/* The pel logging code needs a system-id property to work so
 	   make sure we have one. */
 	astbmc_fixup_dt_system_id();
@@ -412,7 +425,16 @@ void astbmc_early_init(void)
 		} else
 			prerror("PLAT: AST IO initialisation failed!\n");
 
-		ast_setup_sio_mbox(MBOX_IO_BASE, MBOX_LPC_IRQ);
+		/*
+		 * P9 prefers IPMI for HIOMAP but will use MBOX if IPMI is not
+		 * supported. P8 either uses IPMI HIOMAP or direct IO, and
+		 * never MBOX. Thus only populate the MBOX node on P9 to allow
+		 * fallback.
+		 */
+		if (proc_gen == proc_gen_p9) {
+			astbmc_fixup_dt_mbox(dt_find_primary_lpc());
+			ast_setup_sio_mbox(MBOX_IO_BASE, MBOX_LPC_IRQ);
+		}
 	} else {
 		/*
 		 * This may or may not be an error depending on if we set up