Subject: [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry

From: [email-masked] (Ivaylo Dimitrov)
Date: Wed, 23 Dec 2015 16:54:32 +0200

Hi,

On 15.12.2015 14:20, Russell King - ARM Linux wrote:
>
> You could also just save_atags() in there, with a comment saying that
> this is a work-around for N900 which needs the ATAGs saved, and this
> is allowed in ->reserve as a special exception.
>

What about this (just to confirm I got the idea correctly, proper patch 
will follow if that's the case):

diff --git a/arch/arm/mach-omap2/board-generic.c 
b/arch/arm/mach-omap2/board-generic.c
index 34ff14b..8916856 100644
--- a/arch/arm/mach-omap2/board-generic.c
+++ b/arch/arm/mach-omap2/board-generic.c
@@ -83,8 +83,25 @@ static const char *const n900_boards_compat[] 
__initconst = {
         NULL,
  };

+#ifdef CONFIG_ATAGS_PROC
+extern void save_atags(const struct tag *tags);
+
+/* Legacy userspace on Nokia N900 needs ATAGS exported in /proc/atags,
+ * save them while the data is still not overwritten
+ */
+static void __init rx51_reserve(void)
+{
+       const phys_addr_t __atags_pointer = 0x100;
+
+       save_atags(phys_to_virt(__atags_pointer));
+       omap_reserve();
+}
+#else
+#define rx51_reserve omap_reserve
+#endif
+
  DT_MACHINE_START(OMAP3_N900_DT, "Nokia RX-51 board")
-       .reserve        = omap_reserve,
+       .reserve        = rx51_reserve,
         .map_io         = omap3_map_io,
         .init_early     = omap3430_init_early,
         .init_machine   = omap_generic_init,