On 12/31/17 22:59, kevans@xxxxxxxxxxx wrote:
> Currently, references cannot be made to nodes in the base that do not already
> have phandles, limiting us to nodes that have been referenced in the base fdt.
> Lift that restriction by allocating them on an as-needed basis.
I am very confused. If I understand correctly, the problem is:
A base devicetree contains a __symbols__ node, where one of the properties
in that node has a value which is a path to a node, where that node does
not have a phandle property.
Is that correct?
>
> Signed-off-by: Kyle Evans <kevans@xxxxxxxxxxx>
> ---
>
> Changes since v1:
> - Added a function to grab the next phandle; once we've assigned one phandle
> to a node automatically, we'll need to choose max phandle from the base
> blob instead of the overlay since they've not necessarily been merged yet.
>
> libfdt/fdt_overlay.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 74 insertions(+), 9 deletions(-)
>
> diff --git a/libfdt/fdt_overlay.c b/libfdt/fdt_overlay.c
> index bd81241..10a57ae 100644
> --- a/libfdt/fdt_overlay.c
> +++ b/libfdt/fdt_overlay.c
> @@ -335,6 +335,66 @@ static int overlay_update_local_references(void *fdto, uint32_t delta)
> delta);
> }
>
> +/**
> + * overlay_next_phandle - Grab next phandle to be assigned
> + * @fdt: Base Device Tree blob
> + * @fdto: Device tree overlay blob
> + *
> + * overlay_next_phandle() determines the next phandle to be assigned to the
> + * fdt blob.
> + *
> + * This is part of the device tree overlay application process, when you need to
> + * assign a phandle to a node that doesn't currently have one.
> + *
> + * returns:
> + * Next phandle to be assigned on success
> + * Negative error code on failure
> + */
> +static int overlay_next_phandle(void *fdt, void *fdto)
> +{
> + int base_max, overlay_max;
> +
> + base_max = fdt_get_max_phandle(fdt);
> + if (base_max < 0)
> + return base_max;
> + overlay_max = fdt_get_max_phandle(fdto);
> + if (overlay_max < 0)
> + return overlay_max;
> + return (base_max > overlay_max ? base_max : overlay_max) + 1;
> +}
> +
> +/**
> + * overlay_assign_phandle - Assign a phandle to a symbol in the base fdt
> + * @fdt: Base Device Tree blob
> + * @fdto: Device tree overlay blob
> + * @symbol_off: Node offset of the symbol to be assigned a phandle
> + *
> + * overlay_assign_phandle() assigns the next phandle available to the requested
> + * node in the base device tree.
> + *
> + * This is part of the device tree overlay application process, when you want to
> + * reference a symbol in the base device tree that doesn't yet have a phandle.
> + *
> + * returns:
> + * phandle assigned on success
> + * 0 on failure
> + */
> +static int overlay_assign_phandle(void *fdt, void *fdto, int symbol_off)
> +{
> + int phandle, ret;
> + fdt32_t phandle_val;
> +
> + /* Overlay phandles have already been adjusted, grab highest phandle */
> + phandle = overlay_next_phandle(fdt, fdto);
> + if (phandle < 0)
> + return 0;
> + phandle_val = cpu_to_fdt32(phandle);
> + ret = fdt_setprop(fdt, symbol_off, "phandle", &phandle_val, sizeof(phandle_val));
> + if (!ret)
> + return phandle;
> + return 0;
> +}
> +
> /**
> * overlay_fixup_one_phandle - Set an overlay phandle to the base one
> * @fdt: Base Device Tree blob
> @@ -359,7 +419,7 @@ static int overlay_update_local_references(void *fdto, uint32_t delta)
> * Negative error code on failure
> */
> static int overlay_fixup_one_phandle(void *fdt, void *fdto,
> - int symbols_off,
> + int *symbols_off,
> const char *path, uint32_t path_len,
> const char *name, uint32_t name_len,
> int poffset, const char *label)
> @@ -370,10 +430,10 @@ static int overlay_fixup_one_phandle(void *fdt, void *fdto,
> int symbol_off, fixup_off;
> int prop_len;
>
> - if (symbols_off < 0)
> - return symbols_off;
> + if (*symbols_off < 0)
> + return *symbols_off;
>
> - symbol_path = fdt_getprop(fdt, symbols_off, label,
> + symbol_path = fdt_getprop(fdt, *symbols_off, label,
> &prop_len);
> if (!symbol_path)
> return prop_len;
> @@ -383,8 +443,14 @@ static int overlay_fixup_one_phandle(void *fdt, void *fdto,
> return symbol_off;
>
> phandle = fdt_get_phandle(fdt, symbol_off);
> - if (!phandle)
> - return -FDT_ERR_NOTFOUND;
> + if (!phandle) {
> + phandle = overlay_assign_phandle(fdt, fdto, symbol_off);
> + if (phandle == 0)
> + return -FDT_ERR_NOTFOUND;
> +
> + /* Re-lookup symbols offset, it's been invalidated */
> + *symbols_off = fdt_path_offset(fdt, "/__symbols__");
> + }
>
> fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
> if (fixup_off == -FDT_ERR_NOTFOUND)
> @@ -418,7 +484,7 @@ static int overlay_fixup_one_phandle(void *fdt, void *fdto,
> * 0 on success
> * Negative error code on failure
> */
> -static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
> +static int overlay_fixup_phandle(void *fdt, void *fdto, int *symbols_off,
> int property)
> {
> const char *value;
> @@ -519,8 +585,7 @@ static int overlay_fixup_phandles(void *fdt, void *fdto)
>
> fdt_for_each_property_offset(property, fdto, fixups_off) {
> int ret;
> -
> - ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property);
> + ret = overlay_fixup_phandle(fdt, fdto, &symbols_off, property);
> if (ret)
> return ret;
> }
>
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