Re: [Minios-devel] [UNIKRAFT PATCH 5/8] lib/fdt: Introduce a fdt_get_address helper

[Mark Rutland <mark.rutland@xxxxxxx>]

On Thu, Dec 13, 2018 at 09:18:17AM +0000, Wei Chen wrote:
> This helper will be used very frequently for device libraries
> to parse their addresses. Introduce this helper to avoid using
> fdt_address_cells and fdt_size_cells everywhere.
> 
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> Signed-off-by: Jianyong Wu <jianyong.wu@xxxxxxx>
> ---
>  lib/fdt/exportsyms.uk    |  1 +
>  lib/fdt/fdt_addresses.c  | 50 ++++++++++++++++++++++++++++++++++++++++
>  lib/fdt/include/libfdt.h | 18 +++++++++++++++
>  3 files changed, 69 insertions(+)
> 
> diff --git a/lib/fdt/exportsyms.uk b/lib/fdt/exportsyms.uk
> index b11df90..c893caf 100644
> --- a/lib/fdt/exportsyms.uk
> +++ b/lib/fdt/exportsyms.uk
> @@ -62,3 +62,4 @@ fdt_resize
>  fdt_overlay_apply
>  fdt_getprop_u32_by_offset
>  fdt_interrupt_cells
> +fdt_get_address
> diff --git a/lib/fdt/fdt_addresses.c b/lib/fdt/fdt_addresses.c
> index bccb11c..b186fc0 100644
> --- a/lib/fdt/fdt_addresses.c
> +++ b/lib/fdt/fdt_addresses.c
> @@ -64,3 +64,53 @@ int fdt_size_cells(const void *fdt, int nodeoffset)
>  {
>       return fdt_get_cells(fdt, "#size-cells", nodeoffset);
>  }
> +
> +static uint64_t fdt_reg_read_number(const fdt32_t *regs, uint32_t size)
> +{
> +     uint64_t number = 0;
> +
> +     if (size >= 3 || size <= 0)
> +             return -FDT_ERR_BADNCELLS;
> +
> +     for(uint32_t i = 0; i < size; i++) {
> +             number <<= 32;
> +             number |= fdt32_to_cpu(*regs);
> +             regs++;
> +     }
> +
> +     return number;
> +}
> +
> +int fdt_get_address(const void *fdt, int nodeoffset, int index,
> +                     uint64_t *addr, uint64_t *size)
> +{
> +     int len, prop_addr, prop_size;
> +     int naddr, nsize, term_size;
> +     const void *regs;
> +
> +     naddr = fdt_address_cells(fdt, nodeoffset);
> +     if (naddr < 0 || naddr >= FDT_MAX_NCELLS)
> +             return -FDT_ERR_BADNCELLS;
> +
> +     nsize = fdt_size_cells(fdt, nodeoffset);
> +     if (nsize < 0 || nsize >= FDT_MAX_NCELLS)
> +             return -FDT_ERR_BADNCELLS;
> +
> +     /* Get reg content */
> +     regs = fdt_getprop(fdt, nodeoffset, "reg", &len);
> +     if (regs == NULL)
> +             return -FDT_ERR_NOTFOUND;
> +
> +     term_size = (int)sizeof(fdt32_t) * (nsize + naddr);
> +     prop_addr = term_size * index;
> +     prop_size = prop_addr + (int)sizeof(fdt32_t) * naddr;
> +
> +     /* The reg content must cover the reg term[index] at least */
> +     if (len < (prop_addr + term_size))
> +             return -FDT_ERR_NOSPACE;
> +
> +     *addr = fdt_reg_read_number(regs + prop_addr, naddr);
> +     *size = fdt_reg_read_number(regs + prop_size, nsize);
> +
> +     return 0;
> +}

If this is intended to extract addresses, shouldn't it take ranges
properties into account?

Thanks,
Mark.

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