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authorPeter Hurley <peter@hurleysoftware.com>2015-03-09 16:27:21 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-26 17:25:27 +0100
commit470ca0de69feaba5df215ad804cec1859883a5ed (patch)
treef6881a136d161bb131d56b9b68860568756b53eb /include/asm-generic
parent7c53cb3de493573dc3b7f2468a542a9f11cc5079 (diff)
downloadop-kernel-dev-470ca0de69feaba5df215ad804cec1859883a5ed.zip
op-kernel-dev-470ca0de69feaba5df215ad804cec1859883a5ed.tar.gz
serial: earlycon: Enable earlycon without command line param
Earlycon matching can only be triggered if 'earlycon=...' has been specified on the kernel command line. To workaround this limitation requires tight coupling between arches and specific serial drivers in order to start an earlycon. Devicetree avoids this limitation with a link table that contains the required data to match earlycons. Mirror this approach for earlycon match by name. Re-purpose EARLYCON_DECLARE to generate a table entry which associates name with setup() function. Re-purpose setup_earlycon() to scan this table for an earlycon match, which is registered if found. Declare one "earlycon" early_param, which calls setup_earlycon(). This design allows setup_earlycon() to be called directly with a param string (as if 'earlycon=...' had been set on the command line). Re-registration (either directly or by early_param) is prevented. Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/vmlinux.lds.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index ac78910..87e5b6f 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -150,6 +150,14 @@
#define TRACE_SYSCALLS()
#endif
+#ifdef CONFIG_SERIAL_EARLYCON
+#define EARLYCON_TABLE() . = ALIGN(8); \
+ VMLINUX_SYMBOL(__earlycon_table) = .; \
+ *(__earlycon_table) \
+ *(__earlycon_table_end)
+#else
+#define EARLYCON_TABLE()
+#endif
#define ___OF_TABLE(cfg, name) _OF_TABLE_##cfg(name)
#define __OF_TABLE(cfg, name) ___OF_TABLE(cfg, name)
@@ -503,6 +511,7 @@
CPU_METHOD_OF_TABLES() \
KERNEL_DTB() \
IRQCHIP_OF_MATCH_TABLE() \
+ EARLYCON_TABLE() \
EARLYCON_OF_TABLES()
#define INIT_TEXT \
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