[U-Boot,v2] cmd, fdt: add subcommand "get" to fdt header

store fdt header member with name <member> in U-Boot
Environment variable with name <var>.

for example to get the total length of the fdt and store
it in filesize, call:

fdt header get filesize totalsize

For membernames look into fdt header definition at
scripts/dtc/libfdt/libfdt.h

Signed-off-by: Heiko Schocher <hs@denx.de>
---

Changes in v2:
- add obviously missing "static const char *"

  cmd/fdt.c | 40 +++++++++++++++++++++++++++++++++++++++-
  1 file changed, 39 insertions(+), 1 deletion(-)

On 11/14/2018 04:17 PM, Heiko Schocher wrote:
> store fdt header member with name <member> in U-Boot
> Environment variable with name <var>.
> 
> for example to get the total length of the fdt and store
> it in filesize, call:
> 
> fdt header get filesize totalsize
> 
> For membernames look into fdt header definition at
> scripts/dtc/libfdt/libfdt.h
> 
> Signed-off-by: Heiko Schocher <hs@denx.de>
> ---
> 
> Changes in v2:
> - add obviously missing "static const char *"
> 
>  cmd/fdt.c | 40 +++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/cmd/fdt.c b/cmd/fdt.c
> index 8a19a3fdbf..501aa7c887 100644
> --- a/cmd/fdt.c
> +++ b/cmd/fdt.c
> @@ -73,6 +73,40 @@ static int fdt_value_env_set(const void *nodep, int
> len, const char *var)
>      return 0;
>  }
> 
> +static const char * const fdt_member_table[] = {
> +    "magic",
> +    "totalsize",
> +    "off_dt_struct",
> +    "off_dt_strings",
> +    "off_mem_rsvmap",
> +    "version",
> +    "last_comp_version",
> +    "boot_cpuid_phys",
> +    "size_dt_strings",
> +    "size_dt_struct",
> +};
> +
> +static int fdt_get_header_value(int argc, char * const argv[])
> +{
> +    fdt32_t *fdtp = (fdt32_t *)working_fdt;
> +    ulong val;
> +    int i;
> +
> +    if (argv[2][0] != 'g')
> +        return CMD_RET_FAILURE;
> +
> +    for (i = 0; i < ARRAY_SIZE(fdt_member_table); i++) {
> +        if (strcmp(fdt_member_table[i], argv[4]) == 0) {

if (strcmp...)
 continue;

> +            val = fdt32_to_cpu(*fdtp);

You can use fdtp[i]

> +            env_set_hex(argv[3], val);
> +            return CMD_RET_SUCCESS;
> +        }
> +        fdtp++;

And drop this

> +    }

Looks great otherwise

> +    return CMD_RET_FAILURE;
> +}
> +
>  /*
>   * Flattened Device Tree command, see the help for parameter definitions.
>   */
> @@ -491,6 +525,9 @@ static int do_fdt(cmd_tbl_t *cmdtp, int flag, int
> argc, char * const argv[])
>       * Display header info
>       */
>      } else if (argv[1][0] == 'h') {
> +        if (argc == 5)
> +            return fdt_get_header_value(argc, argv);
> +
>          u32 version = fdt_version(working_fdt);
>          printf("magic:\t\t\t0x%x\n", fdt_magic(working_fdt));
>          printf("totalsize:\t\t0x%x (%d)\n", fdt_totalsize(working_fdt),
> @@ -1090,7 +1127,8 @@ static char fdt_help_text[] =
>      "fdt set    <path> <prop> [<val>]    - Set <property> [to <val>]\n"
>      "fdt mknode <path> <node>            - Create a new node after
> <path>\n"
>      "fdt rm     <path> [<prop>]          - Delete the node or
> <property>\n"
> -    "fdt header                          - Display header info\n"
> +    "fdt header [get <var> <member>]     - Display header info\n"
> +    "                                      get - get header member
> <member> and store it in <var>\n"
>      "fdt bootcpu <id>                    - Set boot cpuid\n"
>      "fdt memory <addr> <size>            - Add/Update memory node\n"
>      "fdt rsvmem print                    - Show current mem reserves\n"