Re: [PATCH 3/4] libfdt: Add max phandle retrieval function

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

[-- Attachment #1: Type: text/plain, Size: 2515 bytes --]

On Fri, May 27, 2016 at 10:28:48AM +0200, Maxime Ripard wrote:
> Add a function to retrieve the highest phandle in a given device tree.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>

Needs a testcase, plus a couple of smallish problems:

> ---
>  libfdt/fdt_ro.c | 15 +++++++++++++++
>  libfdt/libfdt.h | 13 +++++++++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
> index 50cce864283c..d5a14178190f 100644
> --- a/libfdt/fdt_ro.c
> +++ b/libfdt/fdt_ro.c
> @@ -88,6 +88,21 @@ static int _fdt_string_eq(const void *fdt, int stroffset,
>  	return (strlen(p) == len) && (memcmp(p, s, len) == 0);
>  }
>  
> +uint32_t fdt_get_max_phandle(const void *fdt)
> +{
> +	uint32_t max_phandle = 0, phandle;
> +	int offset;
> +
> +	for (offset = fdt_next_node(fdt, -1, NULL); offset >= 0;
> +	     offset = fdt_next_node(fdt, offset, NULL)) {
> +		phandle = fdt_get_phandle(fdt, offset);

I think you need to check for the case of an invalid -1 valued phandle
- otherwise if there are any of those, it will come up as the max
(unsigned comparison).

> +		if (phandle > max_phandle)
> +			max_phandle = phandle;
> +	}

You need to check for offset != -FDT_ERR_NOTFOUND, which would
indicate some other error from fdt_next_node.

> +
> +	return max_phandle;
> +}
> +
>  int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
>  {
>  	FDT_CHECK_HEADER(fdt);
> diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> index 6589e08db7ab..7156b264b1e9 100644
> --- a/libfdt/libfdt.h
> +++ b/libfdt/libfdt.h
> @@ -284,6 +284,19 @@ int fdt_move(const void *fdt, void *buf, int bufsize);
>  const char *fdt_string(const void *fdt, int stroffset);
>  
>  /**
> + * fdt_get_max_phandle - retrieves the highest phandle in a tree
> + * @fdt: pointer to the device tree blob
> + *
> + * fdt_get_max_phandle retrieves the highest phandlle in the given
> + * device tree
> + *
> + * returns:
> + *      the highest phandle on success
> + *      0, if an error occured
> + */
> +uint32_t fdt_get_max_phandle(const void *fdt);
> +
> +/**
>   * fdt_num_mem_rsv - retrieve the number of memory reserve map entries
>   * @fdt: pointer to the device tree blob
>   *

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]