Re: [PATCH v2] xen/arm, device-tree: Make static-mem use #{address,size}-cells

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 9 Sep 2022, Henry Wang wrote:
> In order to keep consistency in the device tree binding, there is
> no need for static memory allocation feature to define a specific
> set of address and size cells for "xen,static-mem" property.
> 
> Therefore, this commit reuses the regular #{address,size}-cells
> for parsing the device tree "xen,static-mem" property. Update
> the documentation accordingly.
> 
> Also, take the chance to remove the unnecessary "#address-cells"
> and "#size-cells" in the domU1 node of the device tree to only
> emphasize the related part that the example is showing.
> 
> Signed-off-by: Henry Wang <Henry.Wang@xxxxxxx>

Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> Changes from v1 to v2:
> - Remove the "----" addition, as it is unnecessary to this patch.
> - Mention the removal of #address-cells and #size-cells in domU1
>   node in the commit message.
> ---
>  docs/misc/arm/device-tree/booting.txt | 11 +++++------
>  docs/misc/arm/passthrough-noiommu.txt |  7 +++----
>  xen/arch/arm/bootfdt.c                |  5 -----
>  xen/arch/arm/domain_build.c           | 16 ++--------------
>  4 files changed, 10 insertions(+), 29 deletions(-)
> 
> diff --git a/docs/misc/arm/device-tree/booting.txt 
> b/docs/misc/arm/device-tree/booting.txt
> index 5395a1077c..10caf4f1af 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -350,8 +350,8 @@ areas are pre-defined by configuration using physical 
> address ranges.
>  
>  Memory can be statically allocated to a domain using the property 
> "xen,static-
>  mem" defined in the domain configuration. The number of cells for the address
> -and the size must be defined using respectively the properties
> -"#xen,static-mem-address-cells" and "#xen,static-mem-size-cells".
> +and the size must be defined respectively by the parent node properties
> +"#address-cells" and "#size-cells".
>  
>  The property 'memory' is still needed and should match the amount of memory
>  given to the guest. Currently, it either comes from static memory or lets Xen
> @@ -366,14 +366,13 @@ device-tree:
>  
>      / {
>          chosen {
> +            #address-cells = <0x1>;
> +            #size-cells = <0x1>;
> +            ...
>              domU1 {
>                  compatible = "xen,domain";
> -                #address-cells = <0x2>;
> -                #size-cells = <0x2>;
>                  cpus = <2>;
>                  memory = <0x0 0x80000>;
> -                #xen,static-mem-address-cells = <0x1>;
> -                #xen,static-mem-size-cells = <0x1>;
>                  xen,static-mem = <0x30000000 0x20000000>;
>                  ...
>              };
> diff --git a/docs/misc/arm/passthrough-noiommu.txt 
> b/docs/misc/arm/passthrough-noiommu.txt
> index 3e2ef21ad7..69b8de1975 100644
> --- a/docs/misc/arm/passthrough-noiommu.txt
> +++ b/docs/misc/arm/passthrough-noiommu.txt
> @@ -33,14 +33,13 @@ on static allocation in the device-tree:
>  
>  / {
>       chosen {
> +             #address-cells = <0x1>;
> +             #size-cells = <0x1>;
> +             ...
>               domU1 {
>                       compatible = "xen,domain";
> -                     #address-cells = <0x2>;
> -                     #size-cells = <0x2>;
>                       cpus = <2>;
>                       memory = <0x0 0x80000>;
> -                     #xen,static-mem-address-cells = <0x1>;
> -                     #xen,static-mem-size-cells = <0x1>;
>                       xen,static-mem = <0x30000000 0x20000000>;
>                       direct-map;
>                       ...
> diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
> index 9e1ea60094..59675f086b 100644
> --- a/xen/arch/arm/bootfdt.c
> +++ b/xen/arch/arm/bootfdt.c
> @@ -370,11 +370,6 @@ static int __init process_domain_node(const void *fdt, 
> int node,
>          /* No "xen,static-mem" present. */
>          return 0;
>  
> -    address_cells = device_tree_get_u32(fdt, node,
> -                                        "#xen,static-mem-address-cells", 0);
> -    size_cells = device_tree_get_u32(fdt, node,
> -                                     "#xen,static-mem-size-cells", 0);
> -
>      return device_tree_get_meminfo(fdt, node, "xen,static-mem", 
> address_cells,
>                                     size_cells, &bootinfo.reserved_mem,
>                                     MEMBANK_STATIC_DOMAIN);
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 7412303d20..9040a8c6cb 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -565,21 +565,9 @@ static int __init parse_static_mem_prop(const struct 
> dt_device_node *node,
>      const struct dt_property *prop;
>  
>      prop = dt_find_property(node, "xen,static-mem", NULL);
> -    if ( !dt_property_read_u32(node, "#xen,static-mem-address-cells",
> -                               addr_cells) )
> -    {
> -        printk(XENLOG_ERR
> -               "failed to read \"#xen,static-mem-address-cells\".\n");
> -        return -EINVAL;
> -    }
>  
> -    if ( !dt_property_read_u32(node, "#xen,static-mem-size-cells",
> -                               size_cells) )
> -    {
> -        printk(XENLOG_ERR
> -               "failed to read \"#xen,static-mem-size-cells\".\n");
> -        return -EINVAL;
> -    }
> +    *addr_cells = dt_n_addr_cells(node);
> +    *size_cells = dt_n_size_cells(node);
>  
>      *cell = (const __be32 *)prop->value;
>      *length = prop->length;
> -- 
> 2.17.1
>