[Skiboot] [PATCH v2 09/12] opal: Inform fsp about the topology switch.

[Mahesh J Salgaonkar]

From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

After the topology switch, we may have a non-functional backup topology.
This means, we won't be able to recover from future TOD errors that
requires topology switch. Someone needs to either fix it OR configure
new functional backup topology.

Bit 18 of the Pervasive local FIR (SCOM: EH.TPCHIP.TPC.LOCAL_FIR: 0x0104000C)
is used to signal that TOD error analysis needs to be performed. This
allows FSP/PRD to investigate and re-configure new backup topology if
required. Once new backup topology is configured and ready, FSP sends a
mailbox command xE6, s/c 0x06, mod 0, to enable the backup topology.

This isn't documented anywhere. This info is provided by FSP folks.

This patch implements setting of bit 18 in Pervasive local FIR. The next
patch will handle FSP mailbox command xE6, s/c 0x06, mod 0.

Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
---
 hw/chiptod.c |   33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/hw/chiptod.c b/hw/chiptod.c
index 7841127..8ccfed8 100644
--- a/hw/chiptod.c
+++ b/hw/chiptod.c
@@ -97,6 +97,10 @@
 /* -- TOD Error interrupt register -- */
 #define TOD_ERROR_INJECT		0x00040031
 
+/* Local FIR EH.TPCHIP.TPC.LOCAL_FIR */
+#define LOCAL_CORE_FIR		0x0104000C
+#define LFIR_SWITCH_COMPLETE	PPC_BIT(18)
+
 /* Magic TB value. One step cycle ahead of sync */
 #define INIT_TB	0x000000000001ff0
 
@@ -1046,6 +1050,33 @@ static bool chiptod_backup_valid(void)
 	return false;
 }
 
+static void chiptod_topology_switch_complete(void)
+{
+	/*
+	 * After the topology switch, we may have a non-functional backup
+	 * topology, and we won't be able to recover from future TOD errors
+	 * that requires topology switch. Someone needs to either fix it OR
+	 * configure new functional backup topology.
+	 *
+	 * Bit 18 of the Pervasive FIR is used to signal that TOD error
+	 * analysis needs to be performed. This allows FSP/PRD to
+	 * investigate and re-configure new backup topology if required.
+	 * Once new backup topology is configured and ready, FSP sends a
+	 * mailbox command xE6, s/c 0x06, mod 0, to enable the backup
+	 * topology.
+	 *
+	 * This isn't documented anywhere. This info is provided by FSP
+	 * folks.
+	 */
+	if (xscom_writeme(LOCAL_CORE_FIR, LFIR_SWITCH_COMPLETE) != 0) {
+		prerror("CHIPTOD: XSCOM error writing LOCAL_CORE_FIR\n");
+		return;
+	}
+
+	prlog(PR_DEBUG, "CHIPTOD: Topology switch complete\n");
+	print_topology_info();
+}
+
 /*
  * Sync up TOD with other chips and get TOD in running state.
  * Check if current topology is active and running. If not, then
@@ -1111,6 +1142,8 @@ static int chiptod_start_tod(void)
 			prerror("CHIPTOD: XSCOM error enabling steppers\n");
 			return 0;
 		}
+
+		chiptod_topology_switch_complete();
 	}
 
 	if (!chiptod_master_running()) {