[Skiboot] [PATCH v6 17/22] fadump: Add support to trigger memory preserving IPL on BMC system

[Vasant Hegde]

On FSP based system we call 'attn' instruction. FSP detects attention and
initiates memory preserving IPL. On BMC system we have to call SBE S0
interrupt to initiate memory preserving IPL.

This patch adds support to call SBE S0 interrupt in assert path.
Sequence :
  - S0 interrupt on slave chip SBE
  - S0 interrupt on master chip SBE

Note that this is hooked to ipmi_terminate path. We have HDAT flag for MPIPL
support. If MPIPL is not supported then we don't create 'ibm,opal/dump' node
and we will fall back to existing termination flow.

Note:
  - It uses xscom node to detect master and slave chip. So that we can
    trigger early MPIPL (even before initializing SBE driver).
  - At present we do not have a proper way to detect SBE is alive or not.
    So we wait for predefined time and then call normal reboot.

Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
---
 hw/ipmi/ipmi-attn.c |  4 ++++
 hw/sbe-p9.c         | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 include/sbe-p9.h    | 10 +++++++++
 3 files changed, 76 insertions(+)

diff --git a/hw/ipmi/ipmi-attn.c b/hw/ipmi/ipmi-attn.c
index 8ff872c62..cf605feaf 100644
--- a/hw/ipmi/ipmi-attn.c
+++ b/hw/ipmi/ipmi-attn.c
@@ -19,6 +19,7 @@
 #include <pel.h>
 #include <platform.h>
 #include <processor.h>
+#include <sbe-p9.h>
 #include <skiboot.h>
 #include <stack.h>
 #include <timebase.h>
@@ -65,6 +66,9 @@ static void ipmi_log_terminate_event(const char *msg)
 
 void __attribute__((noreturn)) ipmi_terminate(const char *msg)
 {
+	/* If MPIPL is supported then trigger SBE interrupt to initiate MPIPL */
+	p9_sbe_terminate();
+
 	/* Terminate called before initializing IPMI (early abort) */
 	if (!ipmi_present()) {
 		if (platform.cec_reboot)
diff --git a/hw/sbe-p9.c b/hw/sbe-p9.c
index c193ed075..924f73761 100644
--- a/hw/sbe-p9.c
+++ b/hw/sbe-p9.c
@@ -947,3 +947,65 @@ void p9_sbe_init(void)
 	/* Initiate SBE timeout poller */
 	opal_add_poller(p9_sbe_timeout_poll, NULL);
 }
+
+/* Terminate and initiate MPIPL */
+void p9_sbe_terminate(void)
+{
+	uint32_t chip_id;
+	uint32_t primary_chip = -1;
+	int rc;
+	u64 wait_tb;
+	struct dt_node *xn;
+
+	if (proc_gen < proc_gen_p9)
+		return;
+
+	/* Return if MPIPL is not supported */
+	if (!dt_find_by_path(opal_node, "dump"))
+		return;
+
+	dt_for_each_compatible(dt_root, xn, "ibm,xscom") {
+		chip_id = dt_get_chip_id(xn);
+
+		if (dt_has_node_property(xn, "primary", NULL)) {
+			primary_chip = chip_id;
+			continue;
+		}
+
+		rc = xscom_write(chip_id,
+				 SBE_CONTROL_REG_RW, SBE_CONTROL_REG_S0);
+		/* Initiate normal reboot */
+		if (rc) {
+			prlog(PR_ERR, "Failed to write S0 interrupt [chip id = %x]\n",
+			      chip_id);
+			return;
+		}
+	}
+
+	if (primary_chip == -1) {
+		prlog(PR_ERR, "Master chip ID not found.\n");
+		return;
+	}
+
+	/* Write S0 interrupt on master SBE */
+	rc = xscom_write(primary_chip,
+			 SBE_CONTROL_REG_RW, SBE_CONTROL_REG_S0);
+	/* Initiate normal reboot */
+	if (rc) {
+		prlog(PR_ERR, "Failed to write S0 interrupt [chip id = %x]\n",
+		      primary_chip);
+		return;
+	}
+
+	/* XXX We do not have a way to detect SBE state. Hence wait for max
+	 *     time SBE takes to respond and then trigger normal reboot.
+	 */
+	prlog(PR_DEBUG, "Initiated MPIPL, waiting for SBE to respond...\n");
+	wait_tb = mftb() + msecs_to_tb(SBE_CMD_TIMEOUT_MAX);
+	while (mftb() < wait_tb) {
+		cpu_relax();
+	}
+	prlog(PR_ERR, "SBE did not respond within timeout period (%d secs).\n",
+	      SBE_CMD_TIMEOUT_MAX / 1000);
+	prlog(PR_ERR, "Falling back to normal reboot\n");
+}
diff --git a/include/sbe-p9.h b/include/sbe-p9.h
index 5f36cb39e..6a852edc2 100644
--- a/include/sbe-p9.h
+++ b/include/sbe-p9.h
@@ -103,6 +103,13 @@
 #define SBE_HOST_TIMER_EXPIRY		PPC_BIT(14)
 #define SBE_HOST_RESPONSE_MASK		(PPC_BITMASK(0, 4) | SBE_HOST_TIMER_EXPIRY)
 
+/* SBE Control Register */
+#define SBE_CONTROL_REG_RW		0x00050008
+
+/* SBE interrupt s0/s1 bits */
+#define SBE_CONTROL_REG_S0		PPC_BIT(14)
+#define SBE_CONTROL_REG_S1		PPC_BIT(15)
+
 /* SBE Target Type */
 #define SBE_TARGET_TYPE_PROC		0x00
 #define SBE_TARGET_TYPE_EX		0x01
@@ -243,4 +250,7 @@ extern void p9_sbe_update_timer_expiry(uint64_t new_target);
 /* Send skiboot relocated base address to SBE */
 extern void p9_sbe_send_relocated_base(uint64_t reloc_base);
 
+/* Terminate and trigger MPIPL */
+extern void p9_sbe_terminate(void);
+
 #endif	/* __SBE_P9_H */
-- 
2.14.3