ARC: [cmdline] support External Device Trees from u-boot

[~andy/linux] / arch / arc / kernel / setup.c

diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 643eae4436e083959f4679046cdfe01a86d9b039..119dddb752b2892ff81a7ab7ce43011eef056b35 100644 (file)
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -29,7 +29,10 @@
 
 int running_on_hw = 1; /* vs. on ISS */
 
-char __initdata command_line[COMMAND_LINE_SIZE];
+/* Part of U-boot ABI: see head.S */
+int __initdata uboot_tag;
+char __initdata *uboot_arg;
+
 const struct machine_desc *machine_desc;
 
 struct task_struct *_current_task[NR_CPUS];    /* For stack switching */
@@ -311,19 +314,40 @@ void setup_processor(void)
        arc_chk_fpu();
 }
 
+static inline int is_kernel(unsigned long addr)
+{
+       if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
+               return 1;
+       return 0;
+}
+
 void __init setup_arch(char **cmdline_p)
 {
-       /* This also populates @boot_command_line from /bootargs */
-       machine_desc = setup_machine_fdt(__dtb_start);
-       if (!machine_desc)
-               panic("Embedded DT invalid\n");
-
-       /* Append any u-boot provided cmdline */
-#ifdef CONFIG_CMDLINE_UBOOT
-       /* Add a whitespace seperator between the 2 cmdlines */
-       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
-       strlcat(boot_command_line, command_line, COMMAND_LINE_SIZE);
-#endif
+       /* make sure that uboot passed pointer to cmdline/dtb is valid */
+       if (uboot_tag && is_kernel((unsigned long)uboot_arg))
+               panic("Invalid uboot arg\n");
+
+       /* See if u-boot passed an external Device Tree blob */
+       machine_desc = setup_machine_fdt(uboot_arg);    /* uboot_tag == 2 */
+       if (!machine_desc) {
+               /* No, so try the embedded one */
+               machine_desc = setup_machine_fdt(__dtb_start);
+               if (!machine_desc)
+                       panic("Embedded DT invalid\n");
+
+               /*
+                * If we are here, it is established that @uboot_arg didn't
+                * point to DT blob. Instead if u-boot says it is cmdline,
+                * Appent to embedded DT cmdline.
+                * setup_machine_fdt() would have populated @boot_command_line
+                */
+               if (uboot_tag == 1) {
+                       /* Ensure a whitespace between the 2 cmdlines */
+                       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
+                       strlcat(boot_command_line, uboot_arg,
+                               COMMAND_LINE_SIZE);
+               }
+       }
 
        /* Save unparsed command line copy for /proc/cmdline */
        *cmdline_p = boot_command_line;