1 files changed, 57 insertions, 0 deletions
diff --git a/arch/mips/jazz/reset.c b/arch/mips/jazz/reset.c
new file mode 100644
index 0000000000..052b01f5d9
--- /dev/null
+++ b/arch/mips/jazz/reset.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Reset a Jazz machine.
+ *
+ * We don't trust the firmware so we do it the classic way by poking and
+ * stabbing at the keyboard controller ...
+ */
+#include <linux/jiffies.h>
+#include <asm/jazz.h>
+
+#define KBD_STAT_IBF		0x02	/* Keyboard input buffer full */
+
+static void jazz_write_output(unsigned char val)
+{
+	int status;
+
+	do {
+		status = jazz_kh->command;
+	} while (status & KBD_STAT_IBF);
+	jazz_kh->data = val;
+}
+
+static void jazz_write_command(unsigned char val)
+{
+	int status;
+
+	do {
+		status = jazz_kh->command;
+	} while (status & KBD_STAT_IBF);
+	jazz_kh->command = val;
+}
+
+static unsigned char jazz_read_status(void)
+{
+	return jazz_kh->command;
+}
+
+static inline void kb_wait(void)
+{
+	unsigned long start = jiffies;
+	unsigned long timeout = start + HZ/2;
+
+	do {
+		if (! (jazz_read_status() & 0x02))
+			return;
+	} while (time_before_eq(jiffies, timeout));
+}
+
+void jazz_machine_restart(char *command)
+{
+	while(1) {
+		kb_wait();
+		jazz_write_command(0xd1);
+		kb_wait();
+		jazz_write_output(0x00);
+	}
+}