Re: [PATCH] ARM: /proc/atags: Export also for DT

Rob Herring
2015-01-26T20:33:46Z

On Mon, Jan 26, 2015 at 1:16 PM, Pali Rohár <pali.rohar@gmail.com> wrote:
> This patch will cause that decompressor store full ATAG structure into DT tree ("/atags"):
>
> diff --git a/arch/arm/boot/compressed/atags_to_fdt.c b/arch/arm/boot/compressed/atags_to_fdt.c
> index e7e1cc9..1975d7c 100644
> --- a/arch/arm/boot/compressed/atags_to_fdt.c
> +++ b/arch/arm/boot/compressed/atags_to_fdt.c
> @@ -112,7 +112,7 @@ int atags_to_fdt(void *atag_list, void *fdt, int total_space)
> * address and size for each bank */
> uint32_t mem_reg_property[2 * 2 * NR_BANKS];
> int memcount = 0;
> - int ret, memsize;
> + int ret, memsize, atag_size;
>
> /* make sure we've got an aligned pointer */
> if ((u32)atag_list & 0x3)
> @@ -184,6 +184,10 @@ int atags_to_fdt(void *atag_list, void *fdt, int total_space)
> }
> }
>
> + /* include the terminating ATAG_NONE */
> + atag_size = (char *)atag - (char *)atag_list + sizeof(struct tag_header);
> + setprop(fdt, "/", "atags", atag_list, atag_size);
> +
> if (memcount) {
> setprop(fdt, "/memory", "reg", mem_reg_property,
> 4 * memcount * memsize);
>
>
>
> And this patch will export ATAG structure from DT tree ("/atags") into /proc/atags file:

Please properly send your patches.

> diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
> index 9946c1b..0f249a3 100644
> --- a/arch/arm/kernel/devtree.c
> +++ b/arch/arm/kernel/devtree.c
> @@ -29,6 +29,7 @@
> #include <asm/mach-types.h>
> #include <asm/system_info.h>
>
> +#include "atags.h"
>
> #ifdef CONFIG_SMP
> extern struct of_cpu_method __cpu_method_of_table[];
> @@ -254,5 +255,10 @@ const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
> if (prop)
> system_rev = fdt32_to_cpu(*prop);
>
> + /* Save atags */
> + prop = of_get_flat_dt_prop(dt_root, "atags", NULL);
> + if (prop)
> + save_atags((void *)prop);
> +
> return mdesc;
> }
>
>
> Some userspace applications needs access to ATAG structure where can be stored some information passed
> from bootloader to kernel. Example is Nokia N900 device and NOLO bootloader which provides information
> about bootreason (device was started by power button or by alarm or restarted...) and bootmode (normal
> mode or device update mode).

This goes in the commit message.

These would be non-standard fields which are not upstream. I don't
know that we care in that case...

Rob