[PATCH 37/38] MIPS: SGI-IP27: take the console from the KLCONFIG header on IP35

[Imre Kaloz <kaloz@kernel.org>]

An IP35 PROM records its console UART and baud rate in the KLCONFIG
header. That UART is ttyS0 on Fuel and Tezro, so when the record is
present and the command line names no console, prefer ttyS0 at that baud
rate.

Signed-off-by: Imre Kaloz <kaloz@kernel.org>
---
 arch/mips/sgi-ip27/ip27-init.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/arch/mips/sgi-ip27/ip27-init.c b/arch/mips/sgi-ip27/ip27-init.c
index 7f16d7f437c9..6a15ba577b60 100644
--- a/arch/mips/sgi-ip27/ip27-init.c
+++ b/arch/mips/sgi-ip27/ip27-init.c
@@ -6,6 +6,7 @@
  * Copyright (C) 2000 - 2001 by Kanoj Sarcar (kanoj@sgi.com)
  * Copyright (C) 2000 - 2001 by Silicon Graphics, Inc.
  */
+#include <linux/console.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/sched.h>
@@ -164,6 +165,26 @@ static void __init ip27_set_machine_name(void)
 		gfx ? "with" : "without");
 }
 
+/*
+ * Prefer ttyS0 at the baud rate the IP35 PROM recorded for its console
+ * UART in the KLCONFIG header.
+ */
+static void __init ip27_setup_console(void)
+{
+	static char options[8];
+	console_t *cons;
+
+	if (!system_is_ip35 || strstr(arcs_cmdline, "console="))
+		return;
+
+	cons = KL_CONFIG_CH_CONS_INFO(master_nasid);
+	if (!cons->uart_base)
+		return;
+
+	snprintf(options, sizeof(options), "%d", cons->baud);
+	add_preferred_console("ttyS", 0, options);
+}
+
 void __init plat_mem_setup(void)
 {
 	u64 p, e, n_mode;
@@ -215,6 +236,7 @@ void __init plat_mem_setup(void)
 	set_io_port_base(IO_BASE);
 
 	ip27_set_machine_name();
+	ip27_setup_console();
 }
 
 const char *get_system_type(void)
-- 
2.47.3