Hi Simon,
On Sat, Feb 20, 2021 at 7:55 PM Simon Glass <s...@chromium.org> wrote:
>
> Hi Bin,
>
> On Thu, 18 Feb 2021 at 08:58, Bin Meng <bmeng...@gmail.com> wrote:
> >
> > At present fdt_read_prop() can only handle 1 or 2 cells. It is
> > called by fdt_read_range() which may be used to read PCI address
> > from <ranges> for a PCI bus node where the number of PCI address
> > cell is 3. The <ranges> property is an array of:
> >
> > { <child address> <parent address> <size in child address space> }
> >
> > When trying to read <child address> from a PCI bus node using
> > fdt_read_prop(), as the codes below:
> >
> > /* Read <child address> */
> > if (child_addr) {
> > r = fdt_read_prop(ranges, ranges_len, cell, child_addr,
> > acells);
> > if (r)
> > return r;
> > }
> >
> > it will fail, because the PCI child address is made up of 3 cells
> > but fdt_read_prop() cannot handle it. We advance the cell offset
> > by 1 so that the <child address> can be correctly read.
> >
> > This adds the special handling of such case.
> >
> > Signed-off-by: Bin Meng <bmeng...@gmail.com>
> >
> > ---
> >
> > Changes in v2:
> > - add more details in the commit message, and put some comments
> > in the codes to explain why
> >
> > common/fdt_support.c | 20 +++++++++++++++++---
> > 1 file changed, 17 insertions(+), 3 deletions(-)
> >
> > diff --git a/common/fdt_support.c b/common/fdt_support.c
> > index 638eca9..17c54a3 100644
> > --- a/common/fdt_support.c
> > +++ b/common/fdt_support.c
> > @@ -1602,22 +1602,36 @@ u64 fdt_get_base_address(const void *fdt, int node)
> > }
> >
> > /*
> > - * Read a property of size <prop_len>. Currently only supports 1 or 2
> > cells.
> > + * Read a property of size <prop_len>. Currently only supports 1 or 2
> > cells,
> > + * or 3 cells specially for a PCI address.
> > */
> > static int fdt_read_prop(const fdt32_t *prop, int prop_len, int cell_off,
> > uint64_t *val, int cells)
> > {
> > - const fdt32_t *prop32 = &prop[cell_off];
> > - const unaligned_fdt64_t *prop64 = (const fdt64_t *)&prop[cell_off];
> > + const fdt32_t *prop32;
> > + const unaligned_fdt64_t *prop64;
> >
> > if ((cell_off + cells) > prop_len)
> > return -FDT_ERR_NOSPACE;
> >
> > + prop32 = &prop[cell_off];
> > +
> > + /*
> > + * Special handling for PCI address in PCI bus <ranges>
> > + *
> > + * PCI child address is made up of 3 cells. Advance the cell offset
> > + * by 1 so that the PCI child address can be correctly read.
> > + */
> > + if (cells == 3)
> > + cell_off += 1;
> > + prop64 = (const fdt64_t *)&prop[cell_off];
> > +
> > switch (cells) {
> > case 1:
> > *val = fdt32_to_cpu(*prop32);
> > break;
> > case 2:
> > + case 3:
> > *val = fdt64_to_cpu(*prop64);
> > break;
> > default:
> > --
> > 2.7.4
> >
>
> I'm not sure whether this is needed once PPC PCI is converted to DM.
> If not, then perhaps we can revert it later. If it is then it would be
I think we can completely remove these APIs once PPC PCI is converted
to DM. We can revisit this later.
> nice to have a test.
>
> Reviewed-by: Simon Glass <s...@chromium.org>
Regards,
Bin
