From c4dc8ddb1a63cf2e5274d7d03ec6559e2eb28b75 Mon Sep 17 00:00:00 2001
From: Michael Gernoth <michael@gernoth.net>
Date: Wed, 25 May 2011 11:05:07 +0200
Subject: [PATCH] add module to switch kernel serial console to headphone jack

this should provide the kernel messages from the running motorola
kernel on the headset_switch pin of the headphone jack.
Currently untested, as I have no such cable yet. It's also
probably not connected to the currently hardcoded ttyS1.
---
 .gitignore       |  7 +++++++
 Makefile         |  2 +-
 headphone_cons.c | 39 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 headphone_cons.c

diff --git a/.gitignore b/.gitignore
index c6a9045..0f4c01a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,9 @@
 .core.o.cmd
 .driver_sys.o.cmd
 .entry-common.o.cmd
+.headphone_cons.ko.cmd
+.headphone_cons.mod.o.cmd
+.headphone_cons.o.cmd
 .idmap.o.cmd
 .kexec.o.cmd
 .kexec_load.ko.cmd
@@ -24,6 +27,10 @@ copypage-v6.o
 core.o
 driver_sys.o
 entry-common.o
+headphone_cons.ko
+headphone_cons.mod.c
+headphone_cons.mod.o
+headphone_cons.o
 idmap.o
 kexec.o
 kexec_load.ko
diff --git a/Makefile b/Makefile
index 544acff..f0d2079 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,7 @@ KERNEL_RESTART_PREPARE := $(shell grep ' T kernel_restart_prepare$$' $(KDIR)/Sys
 
 EXTRA_CFLAGS += -DCONFIG_KEXEC -Wall -DSYS_CALL_TABLE=0x$(SYS_CALL_TABLE) -DKERNEL_RESTART_PREPARE=0x$(KERNEL_RESTART_PREPARE)
 
-obj-m += kexec_load.o
+obj-m += kexec_load.o headphone_cons.o
 kexec_load-objs := kexec.o machine_kexec.o mmu.o sys.o core.o relocate_kernel.o \
 	proc-v7.o tlb-v7.o cache-v7.o abort-ev7.o pabort-v7.o copypage-v6.o driver_sys.o
 
diff --git a/headphone_cons.c b/headphone_cons.c
new file mode 100644
index 0000000..edf8d16
--- /dev/null
+++ b/headphone_cons.c
@@ -0,0 +1,39 @@
+/*
+ * Provide kernel console on headphone jack
+ */
+
+#include <linux/module.h>
+#include <linux/gpio_mapping.h>
+#include <linux/gpio.h>
+
+/*
+ * int add_preferred_console(char *name, int idx, char *options)
+ * c0069208 T add_preferred_console
+ */
+
+static int (*add_preferred_console)(char *, int, char*) = (int (*)(char*, int, char*))0xc0069208;
+
+static int __init headphone_cons_init(void)
+{
+	int hs_switch;
+
+	/* Get the headset switch gpio number from devtree */
+	hs_switch = get_gpio_by_name("headset_uart_switch");
+	if (hs_switch < 0)
+		return -EINVAL;
+
+	/* configure headset switch gpio as output and
+	   direction based on devtree setting */
+	gpio_request(hs_switch, "mapphone audio headset uart switch");
+
+	/* route kernel uart out headset jack */
+	gpio_direction_output(hs_switch, 0);
+
+	add_preferred_console("ttyS", 1, "115200");
+	return 0;
+}
+
+module_init(headphone_cons_init);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Michael Gernoth <michael@gernoth.net>");
-- 
2.39.2