1 files changed, 47 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-kmsg.c b/arch/powerpc/platforms/powernv/opal-kmsg.c
new file mode 100644
index 000000000..6c3bc4b4d
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-kmsg.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * kmsg dumper that ensures the OPAL console fully flushes panic messages
+ *
+ * Author: Russell Currey <ruscur@russell.cc>
+ *
+ * Copyright 2015 IBM Corporation.
+ */
+
+#include <linux/kmsg_dump.h>
+
+#include <asm/opal.h>
+#include <asm/opal-api.h>
+
+/*
+ * Console output is controlled by OPAL firmware.  The kernel regularly calls
+ * OPAL_POLL_EVENTS, which flushes some console output.  In a panic state,
+ * however, the kernel no longer calls OPAL_POLL_EVENTS and the panic message
+ * may not be completely printed.  This function does not actually dump the
+ * message, it just ensures that OPAL completely flushes the console buffer.
+ */
+static void kmsg_dump_opal_console_flush(struct kmsg_dumper *dumper,
+				     enum kmsg_dump_reason reason)
+{
+	/*
+	 * Outside of a panic context the pollers will continue to run,
+	 * so we don't need to do any special flushing.
+	 */
+	if (reason != KMSG_DUMP_PANIC)
+		return;
+
+	opal_flush_console(0);
+}
+
+static struct kmsg_dumper opal_kmsg_dumper = {
+	.dump = kmsg_dump_opal_console_flush
+};
+
+void __init opal_kmsg_init(void)
+{
+	int rc;
+
+	/* Add our dumper to the list */
+	rc = kmsg_dump_register(&opal_kmsg_dumper);
+	if (rc != 0)
+		pr_err("opal: kmsg_dump_register failed; returned %d\n", rc);
+}