[PATCH] autodetect serial console on efika

[Olaf Hering <olaf@aepfle.de>]

Efika boards have to be booted with console=ttyPSC0 unless there is a
graphics card plugged in. Detect if the firmware stdout is the serial
connector.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
 arch/powerpc/platforms/52xx/efika.c |   50 ++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

--- a/arch/powerpc/platforms/52xx/efika.c
+++ b/arch/powerpc/platforms/52xx/efika.c
@@ -13,6 +13,7 @@
 #include <linux/utsrelease.h>
 #include <linux/pci.h>
 #include <linux/of.h>
+#include <linux/console.h>
 #include <asm/prom.h>
 #include <asm/time.h>
 #include <asm/machdep.h>
@@ -208,12 +209,61 @@ static int __init efika_probe(void)
 	return 1;
 }
 
+/*
+ * Per default, input/output-device points to keyboard/screen
+ * If no card is installed, the built-in serial port is used as a fallback.
+ * But unfortunately, the firmware does not connect /chosen/{stdin,stdout}
+ * the the built-in serial node. Instead, a /failsafe node is created.
+ * More advanced hardware configurations cant be detected,
+ * boot with console=xyz123 to point the kernel to the correct device
+ */
+static void __init efika_init_early(void)
+{
+#ifdef CONFIG_SERIAL_MPC52xx
+	struct device_node *stdout_node;
+	const char *property;
+
+	if (strstr(cmd_line, "console="))
+		return;
+	/* find the boot console from /chosen/stdout */
+	if (!of_chosen)
+		return;
+	property = of_get_property(of_chosen, "linux,stdout-path", NULL);
+	if (!property)
+		return;
+	stdout_node = of_find_node_by_path(property);
+	if (!stdout_node)
+		return;
+	property = of_get_property(stdout_node, "device_type", NULL);
+	if (property && strcmp(property, "serial") == 0) {
+		/*
+		 * The 9pin connector is either /failsafe or /builtin/serial.
+		 * The optional graphics card has also type 'serial' in VGA mode.
+		 */
+		property = of_get_property(stdout_node, "name", NULL);
+		if (property) {
+			if (strcmp(property, "failsafe") == 0)
+				add_preferred_console("ttyPSC", 0, NULL);
+			else {
+				if (strcmp(property, "serial") == 0) {
+					property = of_get_property(stdout_node, "model", NULL);
+					if (property && strcmp(property, "mpc5200-serial") == 0)
+						add_preferred_console("ttyPSC", 0, NULL);
+				}
+			}
+		}
+	}
+	of_node_put(stdout_node);
+#endif
+}
+
 define_machine(efika)
 {
 	.name			= EFIKA_PLATFORM_NAME,
 	.probe			= efika_probe,
 	.setup_arch		= efika_setup_arch,
 	.init			= mpc52xx_declare_of_platform_devices,
+	.init_early		= efika_init_early,
 	.show_cpuinfo		= efika_show_cpuinfo,
 	.init_IRQ		= mpc52xx_init_irq,
 	.get_irq		= mpc52xx_get_irq,