ipmi/wdt: Add ipmi watchdog timer support

Add support for an ipmi watchdog timer. During skiboot initialisation
this patch will cause the system to be reset if opal_run_pollers()
isn't called for more than 60 seconds.

Once the payload is started the watchdog timer will be reset and a
pre-timeout interrupt set. The payload should then receive the
interrupt and call into skiboot which will disable the watchdog timer.

Signed-off-by: Alistair Popple <alistair@popple.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

2 files changed, 128 insertions, 0 deletions

diff --git a/hw/ipmi/Makefile.inc b/hw/ipmi/Makefile.inc
index 02670d7..1c358a9 100644
--- a/hw/ipmi/Makefile.inc
+++ b/hw/ipmi/Makefile.inc
@@ -1,5 +1,6 @@
 SUBDIRS += hw/ipmi
 
 IPMI_OBJS  = ipmi-rtc.o ipmi-power.o ipmi-opal.o ipmi-fru.o ipmi-sel.o
+IPMI_OBJS += ipmi-watchdog.o
 IPMI = hw/ipmi/built-in.o
 $(IPMI): $(IPMI_OBJS:%=hw/ipmi/%)
diff --git a/hw/ipmi/ipmi-watchdog.c b/hw/ipmi/ipmi-watchdog.c
new file mode 100644
index 0000000..de766cf
--- /dev/null
+++ b/hw/ipmi/ipmi-watchdog.c
@@ -0,0 +1,127 @@
+
+/* Copyright 2013-2014 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+#include <ipmi.h>
+#include <lock.h>
+#include <opal.h>
+#include <device.h>
+#include <timer.h>
+#include <timebase.h>
+#include <pool.h>
+#include <skiboot.h>
+
+#define TIMER_USE_DONT_LOG	0x80
+#define TIMER_USE_DONT_STOP	0x40
+#define TIMER_USE_POST		0x02
+
+/* WDT expiration actions */
+#define WDT_PRETIMEOUT_SMI	0x10
+#define WDT_POWER_CYCLE_ACTION 	0x01
+#define WDT_NO_ACTION		0x00
+
+/* How long to set the overall watchdog timeout for. In units of
+ * 100ms. If the timer is not reset within this time the watchdog
+ * expiration action will occur. */
+#define WDT_TIMEOUT		600
+
+/* How often to reset the timer using schedule_timer(). Too short and
+we risk accidently resetting the system due to opal_run_pollers() not
+being called in time, too short and we waste time resetting the wdt
+more frequently than neccessary. */
+#define WDT_MARGIN		300
+
+static struct timer wdt_timer;
+static bool wdt_stopped = false;
+
+static void ipmi_wdt_complete(struct ipmi_msg *msg)
+{
+	if (msg->cmd == IPMI_CMD(IPMI_RESET_WDT) && !msg->user_data)
+		schedule_timer(&wdt_timer, msecs_to_tb(
+				       (WDT_TIMEOUT - WDT_MARGIN)*100));
+
+	ipmi_free_msg(msg);
+}
+
+static void set_wdt(uint8_t action, uint16_t count, uint8_t pretimeout)
+{
+	struct ipmi_msg *ipmi_msg;
+
+	ipmi_msg = ipmi_mkmsg(IPMI_DEFAULT_INTERFACE, IPMI_SET_WDT,
+			      ipmi_wdt_complete, NULL, NULL, 6, 0);
+	if (!ipmi_msg) {
+		prerror("Unable to allocate set wdt message\n");
+		return;
+	}
+	ipmi_msg->error = ipmi_wdt_complete;
+	ipmi_msg->data[0] = TIMER_USE_POST |
+		TIMER_USE_DONT_LOG; 			/* Timer Use */
+	ipmi_msg->data[1] = action;			/* Timer Actions */
+	ipmi_msg->data[2] = pretimeout;			/* Pre-timeout Interval */
+	ipmi_msg->data[3] = 0;				/* Timer Use Flags */
+	ipmi_msg->data[4] = count & 0xff;		/* Initial countdown (lsb) */
+	ipmi_msg->data[5] = (count >> 8) & 0xff;	/* Initial countdown (msb) */
+	ipmi_queue_msg(ipmi_msg);
+}
+
+static void reset_wdt(struct timer *t __unused, void *data)
+{
+	struct ipmi_msg *ipmi_msg;
+
+	ipmi_msg = ipmi_mkmsg(IPMI_DEFAULT_INTERFACE, IPMI_RESET_WDT,
+			      ipmi_wdt_complete, data, NULL, 0, 0);
+	if (!ipmi_msg) {
+		prerror("Unable to allocate reset wdt message\n");
+		return;
+	}
+
+	if (!data)
+		ipmi_queue_msg_sync(ipmi_msg);
+	else
+		ipmi_queue_msg(ipmi_msg);
+}
+
+void ipmi_wdt_stop(void)
+{
+	if (!wdt_stopped) {
+		wdt_stopped = true;
+		set_wdt(WDT_NO_ACTION, 100, 0);
+	}
+}
+
+void ipmi_wdt_final_reset(void)
+{
+	set_wdt(WDT_POWER_CYCLE_ACTION | WDT_PRETIMEOUT_SMI, WDT_TIMEOUT,
+		WDT_MARGIN/10);
+	reset_wdt(NULL, (void *) 1);
+	cancel_timer(&wdt_timer);
+}
+
+void ipmi_wdt_init(void)
+{
+	init_timer(&wdt_timer, reset_wdt, NULL);
+	set_wdt(WDT_POWER_CYCLE_ACTION, WDT_TIMEOUT, 0);
+
+	/* Start the WDT */
+	reset_wdt(NULL, NULL);
+
+	/* For some reason we have to reset it twice to get it to
+	 * actually start the first time. */
+	reset_wdt(NULL, NULL);
+
+	return;
+}