Re: [Xen-devel] [PATCH V1 27/29] xen/dts: device_get_reg: cells are 32 bits big endian value

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-08-28 at 15:47 +0100, Julien Grall wrote:
> Device tree cells are 32-bit big endian value. Use __be32 to avoid confusion
> later.

These are only used by sparse, right? So we wouldn't expect this to
actually save us from any mistakes unless we make Xen support the use of
sparse? (IOW I shouldn't rely on this and not think about this too hard
during patch review because the compiler will get it right for me)

> Also replace get_val call by dt_next_cell.

Would prefer this separately.

> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
(on both patches if you split)

> ---
>  xen/common/device_tree.c |   28 +++++++---------------------
>  1 file changed, 7 insertions(+), 21 deletions(-)
> 
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index b120585..4bc1ce4 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -154,25 +154,11 @@ static bool_t __init device_tree_node_compatible(const 
> void *fdt, int node,
>      return 0;
>  }
>  
> -static void __init get_val(const u32 **cell, u32 cells, u64 *val)
> -{
> -    *val = 0;
> -
> -    if ( cells > 2 )
> -        early_panic("dtb value contains > 2 cells\n");
> -
> -    while ( cells-- )
> -    {
> -        *val <<= 32;
> -        *val |= fdt32_to_cpu(*(*cell)++);
> -    }
> -}
> -
> -static void __init device_tree_get_reg(const u32 **cell, u32 address_cells,
> +static void __init device_tree_get_reg(const __be32 **cell, u32 
> address_cells,
>                                         u32 size_cells, u64 *start, u64 *size)
>  {
> -    get_val(cell, address_cells, start);
> -    get_val(cell, size_cells, size);
> +    *start = dt_next_cell(address_cells, cell);
> +    *size = dt_next_cell(size_cells, cell);
>  }
>  
>  void dt_get_range(const __be32 **cell, const struct dt_device_node *np,
> @@ -327,7 +313,7 @@ static void __init process_memory_node(const void *fdt, 
> int node,
>      const struct fdt_property *prop;
>      int i;
>      int banks;
> -    const u32 *cell;
> +    const __be32 *cell;
>      paddr_t start, size;
>      u32 reg_cells = address_cells + size_cells;
>  
> @@ -345,7 +331,7 @@ static void __init process_memory_node(const void *fdt, 
> int node,
>          return;
>      }
>  
> -    cell = (const u32 *)prop->data;
> +    cell = (const __be32 *)prop->data;
>      banks = fdt32_to_cpu(prop->len) / (reg_cells * sizeof (u32));
>  
>      for ( i = 0; i < banks && early_info.mem.nr_banks < NR_MEM_BANKS; i++ )
> @@ -396,7 +382,7 @@ static void __init process_multiboot_node(const void 
> *fdt, int node,
>                                            u32 address_cells, u32 size_cells)
>  {
>      const struct fdt_property *prop;
> -    const u32 *cell;
> +    const __be32 *cell;
>      int nr;
>      struct dt_mb_module *mod;
>      int len;
> @@ -418,7 +404,7 @@ static void __init process_multiboot_node(const void 
> *fdt, int node,
>          early_panic("fdt: node `%s': `reg` property length is too short\n",
>                      name);
>  
> -    cell = (const u32 *)prop->data;
> +    cell = (const __be32 *)prop->data;
>      device_tree_get_reg(&cell, address_cells, size_cells,
>                          &mod->start, &mod->size);
>  



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