x86: zboot: Allow overriding the command line

When booting Chrome OS images the command line is stored separately
from the kernel. Add a way to specify this address so that images boot
correctly.

Also add comments to the zimage.h header.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: adjust maxargs to 8 for 'zboot start']
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/include/asm/zimage.h b/arch/x86/include/asm/zimage.h
index 80e128c..64c0e6e 100644
--- a/arch/x86/include/asm/zimage.h
+++ b/arch/x86/include/asm/zimage.h
@@ -30,10 +30,38 @@
 #define BZIMAGE_LOAD_ADDR  0x100000
 #define ZIMAGE_LOAD_ADDR   0x10000
 
+/**
+ * load_zimage() - Load a zImage or bzImage
+ *
+ * This copies an image into the standard location ready for setup
+ *
+ * @image: Address of image to load
+ * @kernel_size: Size of kernel including setup block (or 0 if the kernel is
+ *	new enough to have a 'syssize' value)
+ * @load_addressp: Returns the address where the kernel has been loaded
+ * @return address of setup block, or NULL if something went wrong
+ */
 struct boot_params *load_zimage(char *image, unsigned long kernel_size,
 				ulong *load_addressp);
+
+/**
+ * setup_zimage() - Set up a loaded zImage or bzImage ready for booting
+ *
+ * @setup_base: Pointer to the boot parameters, typically at address
+ *	DEFAULT_SETUP_BASE
+ * @cmd_line: Place to put the command line, or NULL to use the one in the setup
+ *	block
+ * @initrd_addr: Address of the initial ramdisk, or 0 if none
+ * @initrd_size: Size of the initial ramdisk, or 0 if none
+ * @load_address: Address where the bzImage is moved before booting, either
+ *	BZIMAGE_LOAD_ADDR or ZIMAGE_LOAD_ADDR
+ * @cmdline_force: Address of 'override' command line, or 0 to use the one in
+ *	the *	setup block
+ * @return 0 (always)
+ */
 int setup_zimage(struct boot_params *setup_base, char *cmd_line, int auto_boot,
-		 unsigned long initrd_addr, unsigned long initrd_size);
+		 ulong initrd_addr, ulong initrd_size, ulong cmdline_force);
+
 void setup_video(struct screen_info *screen_info);
 void setup_efi_info(struct efi_info *efi_info);