Re: [PATCH v5 1/7] xen/arm: introduce new helper device_tree_get_meminfo

[Julien Grall <julien@xen.org>]

Hi Penny,

On 24/08/2021 10:50, Penny Zheng wrote:
> A few functions iterate over the device tree property to get memory info,
> like "reg" or the later "xen,static-mem", so this commit creates a new helper
> device_tree_get_meminfo to extract the common codes.

The commit message needs to be updated as the patch has been reshuffled.

> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
> ---
>   xen/arch/arm/bootfdt.c | 68 ++++++++++++++++++++++++------------------
>   1 file changed, 39 insertions(+), 29 deletions(-)
> 
> diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
> index 476e32e0f5..8c81be3379 100644
> --- a/xen/arch/arm/bootfdt.c
> +++ b/xen/arch/arm/bootfdt.c
> @@ -63,6 +63,44 @@ void __init device_tree_get_reg(const __be32 **cell, u32 address_cells,
>       *size = dt_next_cell(size_cells, cell);
>   }
>   
> +static int __init device_tree_get_meminfo(const void *fdt, int node,
> +                                          const char *prop_name,
> +                                          u32 address_cells, u32 size_cells,
> +                                          void *data)
> +{
> +    const struct fdt_property *prop;
> +    unsigned int i, banks;
> +    const __be32 *cell;
> +    u32 reg_cells = address_cells + size_cells;
> +    paddr_t start, size;
> +    struct meminfo *mem = data;
> +
> +    prop = fdt_get_property(fdt, node, prop_name, NULL);
> +    if ( !prop )
> +        return -ENOENT;
> +
> +    cell = (const __be32 *)prop->data;
> +    banks = fdt32_to_cpu(prop->len) / (reg_cells * sizeof (u32));
> +
> +    for ( i = 0; i < banks && mem->nr_banks < NR_MEM_BANKS; i++ )
> +    {
> +        device_tree_get_reg(&cell, address_cells, size_cells, &start, &size);
> +        /* Some DT may describe empty bank, ignore them */
> +        if ( !size )
> +            continue;
> +        mem->bank[mem->nr_banks].start = start;
> +        mem->bank[mem->nr_banks].size = size;
> +        mem->nr_banks++;
> +    }
> +
> +    if ( i < banks )
> +    {
> +        printk("Warning: Max number of supported memory regions reached.\n");
> +        return -ENOSPC;
> +    }
> +    return 0;
> +}
> +
>   u32 __init device_tree_get_u32(const void *fdt, int node,
>                                  const char *prop_name, u32 dflt)
>   {
> @@ -139,14 +177,6 @@ static int __init process_memory_node(const void *fdt, int node,
>                                         u32 address_cells, u32 size_cells,
>                                         void *data)
>   {
> -    const struct fdt_property *prop;
> -    int i;
> -    int banks;
> -    const __be32 *cell;
> -    paddr_t start, size;
> -    u32 reg_cells = address_cells + size_cells;
> -    struct meminfo *mem = data;
> -
>       if ( address_cells < 1 || size_cells < 1 )

This check will be the same for "xen,static-mem". So can it be moved to 
device_tree_get_meminfo()?

>       {
>           printk("fdt: node `%s': invalid #address-cells or #size-cells",
> @@ -154,27 +184,7 @@ static int __init process_memory_node(const void *fdt, int node,
>           return -EINVAL;
>       }
>   
> -    prop = fdt_get_property(fdt, node, "reg", NULL);
> -    if ( !prop )
> -        return -ENOENT;
> -
> -    cell = (const __be32 *)prop->data;
> -    banks = fdt32_to_cpu(prop->len) / (reg_cells * sizeof (u32));
> -
> -    for ( i = 0; i < banks && mem->nr_banks < NR_MEM_BANKS; i++ )
> -    {
> -        device_tree_get_reg(&cell, address_cells, size_cells, &start, &size);
> -        /* Some DT may describe empty bank, ignore them */
> -        if ( !size )
> -            continue;
> -        mem->bank[mem->nr_banks].start = start;
> -        mem->bank[mem->nr_banks].size = size;
> -        mem->nr_banks++;
> -    }
> -
> -    if ( i < banks )
> -        return -ENOSPC;
> -    return 0;
> +    return device_tree_get_meminfo(fdt, node, "reg", address_cells, size_cells, data);
>   }
>   
>   static int __init process_reserved_memory_node(const void *fdt, int node,
> 

Cheers,

-- 
Julien Grall