sh: Allow for kernel command line concatenation.

So far kernel command line arguments could be passed in by a bootloader
or defined as CONFIG_CMDLINE, which completely overwriting the first one.

This change allows a developer to declare selected kernel parameters in
a kernel configuration (eg. project-specific defconfig), retaining
possibility of passing others by a bootloader.

The obvious examples of the first type are MTD partition or
bigphysarea-like region definitions, while "debug" option or network
configuration should be given by a bootloader or a JTAG boot script.

Signed-off-by: Pawel Moll <pawel.moll@st.com>
Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -767,12 +767,31 @@ config UBC_WAKEUP
 
 	  If unsure, say N.
 
-config CMDLINE_BOOL
-	bool "Default bootloader kernel arguments"
+choice
+	prompt "Kernel command line"
+	optional
+	default CMDLINE_OVERWRITE
+	help
+	  Setting this option allows the kernel command line arguments
+	  to be set.
+
+config CMDLINE_OVERWRITE
+	bool "Overwrite bootloader kernel arguments"
+	help
+	  Given string will overwrite any arguments passed in by
+	  a bootloader.
+
+config CMDLINE_EXTEND
+	bool "Extend bootloader kernel arguments"
+	help
+	  Given string will be concatenated with arguments passed in
+	  by a bootloader.
+
+endchoice
 
 config CMDLINE
-	string "Initial kernel command string"
-	depends on CMDLINE_BOOL
+	string "Kernel command line arguments string"
+	depends on CMDLINE_OVERWRITE || CMDLINE_EXTEND
 	default "console=ttySC1,115200"
 
 endmenu

arch/sh/kernel/setup.c

@@ -404,10 +404,14 @@ void __init setup_arch(char **cmdline_p)
 	if (!memory_end)
 		memory_end = memory_start + __MEMORY_SIZE;
 
-#ifdef CONFIG_CMDLINE_BOOL
+#ifdef CONFIG_CMDLINE_OVERWRITE
 	strlcpy(command_line, CONFIG_CMDLINE, sizeof(command_line));
 #else
 	strlcpy(command_line, COMMAND_LINE, sizeof(command_line));
+#ifdef CONFIG_CMDLINE_EXTEND
+	strlcat(command_line, " ", sizeof(command_line));
+	strlcat(command_line, CONFIG_CMDLINE, sizeof(command_line));
+#endif
 #endif
 
 	/* Save unparsed command line copy for /proc/cmdline */