Re: [PATCH v2 3/6] libfdt: Add max phandle retrieval function

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

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On Mon, Jul 11, 2016 at 09:56:20PM +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>
> Reviewed-by: Stefan Agner <stefan-XLVq0VzYD2Y@public.gmane.org>
> Acked-by: Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>

Reviewed-by: David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>

Although one little nit in the comment that might be worth addressing
if you respin the series.

> ---
>  libfdt/fdt_ro.c     | 26 ++++++++++++++++++++++++++
>  libfdt/libfdt.h     | 14 ++++++++++++++
>  tests/get_phandle.c |  6 ++++++
>  3 files changed, 46 insertions(+)
> 
> diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
> index 50cce864283c..04590984bd51 100644
> --- a/libfdt/fdt_ro.c
> +++ b/libfdt/fdt_ro.c
> @@ -88,6 +88,32 @@ 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;
> +	int offset;
> +
> +	for (offset = fdt_next_node(fdt, -1, NULL);;
> +	     offset = fdt_next_node(fdt, offset, NULL)) {
> +		uint32_t phandle;
> +
> +		if (offset == -FDT_ERR_NOTFOUND)
> +			return max_phandle;
> +
> +		if (offset < 0)
> +			return (uint32_t)-1;
> +
> +		phandle = fdt_get_phandle(fdt, offset);
> +		if (phandle == (uint32_t)-1)
> +			continue;
> +
> +		if (phandle > max_phandle)
> +			max_phandle = phandle;
> +	}
> +
> +	return 0;
> +}
> +
>  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 9d3c9b234274..812937fede44 100644
> --- a/libfdt/libfdt.h
> +++ b/libfdt/libfdt.h
> @@ -283,6 +283,20 @@ 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 phandle in the given
> + * device tree

Perhaps worth mentioning here that this will effectively ignore badly
formatted phandle properties, or phandles with value 0 or -1.

> + * returns:
> + *      the highest phandle on success
> + *      0, if no phandle was found in the device tree
> + *      -1, if an error occurred
> + */
> +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
> diff --git a/tests/get_phandle.c b/tests/get_phandle.c
> index 2079591d4c49..22bd7b81b3f0 100644
> --- a/tests/get_phandle.c
> +++ b/tests/get_phandle.c
> @@ -44,6 +44,7 @@ static void check_phandle(void *fdt, const char *path, uint32_t checkhandle)
>  
>  int main(int argc, char *argv[])
>  {
> +	uint32_t max;
>  	void *fdt;
>  
>  	test_init(argc, argv);
> @@ -53,5 +54,10 @@ int main(int argc, char *argv[])
>  	check_phandle(fdt, "/subnode@2", PHANDLE_1);
>  	check_phandle(fdt, "/subnode@2/subsubnode@0", PHANDLE_2);
>  
> +	max = fdt_get_max_phandle(fdt);
> +	if (max != PHANDLE_2)
> +		FAIL("fdt_get_max_phandle returned 0x%x instead of 0x%x\n",
> +		     max, PHANDLE_2);
> +
>  	PASS();
>  }

-- 
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

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