sparc64: Send break twice from console to return to boot prom

Now we can also jump to boot prom from sunhv console by sending
break twice on console for both running and panicked kernel
cases.

Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: vijaykumar-s

drivers/tty/serial/sunhv.c

@@ -116,7 +116,7 @@ static int receive_chars_getchar(struct uart_port *port)
 
 static int receive_chars_read(struct uart_port *port)
 {
-	int saw_console_brk = 0;
+	static int saw_console_brk;
 	int limit = 10000;
 
 	while (limit-- > 0) {
@@ -128,6 +128,9 @@ static int receive_chars_read(struct uart_port *port)
 			bytes_read = 0;
 
 			if (stat == CON_BREAK) {
+				if (saw_console_brk)
+					sun_do_break();
+
 				if (uart_handle_break(port))
 					continue;
 				saw_console_brk = 1;
@@ -151,6 +154,7 @@ static int receive_chars_read(struct uart_port *port)
 		if (port->sysrq != 0 &&  *con_read_page) {
 			for (i = 0; i < bytes_read; i++)
 				uart_handle_sysrq_char(port, con_read_page[i]);
+			saw_console_brk = 0;
 		}
 
 		if (port->state == NULL)

kernel/panic.c

@@ -273,7 +273,8 @@ void panic(const char *fmt, ...)
 		extern int stop_a_enabled;
 		/* Make sure the user can actually press Stop-A (L1-A) */
 		stop_a_enabled = 1;
-		pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
+		pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
+			 "twice on console to return to the boot prom\n");
 	}
 #endif
 #if defined(CONFIG_S390)