On Tue, Jul 05, 2016 at 10:26:39AM +0200, Maxime Ripard wrote:
> Add a function to retrieve the highest phandle in a given device tree.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
> Reviewed-by: Stefan Agner <stefan@xxxxxxxx>
> Acked-by: Simon Glass <sjg@xxxxxxxxxxxx>
> ---
> include/libfdt.h | 13 +++++++++++++
> lib/libfdt/fdt_ro.c | 26 ++++++++++++++++++++++++++
> 2 files changed, 39 insertions(+)
>
> diff --git a/include/libfdt.h b/include/libfdt.h
> index fbbe58ceb3f1..4643be5adf39 100644
> --- a/include/libfdt.h
> +++ b/include/libfdt.h
> @@ -283,6 +283,19 @@ 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 phandle in the given
> + * device tree
> + *
> + * returns:
> + * the highest phandle on success
> + * 0, if an error occurred
This will also return 0 if there are no phandles in the entire tree,
which isn't exactly an error.
> + */
> +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/lib/libfdt/fdt_ro.c b/lib/libfdt/fdt_ro.c
> index 12214c2dc2b5..503150ef1dc5 100644
> --- a/lib/libfdt/fdt_ro.c
> +++ b/lib/libfdt/fdt_ro.c
> @@ -47,6 +47,32 @@ static int _fdt_string_eq(const void *fdt, int stroffset,
> return (strnlen(p, len + 1) == 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 0;
> +
> + phandle = fdt_get_phandle(fdt, offset);
> + if (phandle == (uint32_t)-1)
> + return 0;
It might be worth pointing out that *any* -1 phandle in the tree
counts as an error. Since -1 phandles are sometimes used as a
placeholder, ignoring them might be a better option.
> + 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);
--
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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