Re: [PATCH v2 6/8] pbl: fdt: add support to parse reserved mem

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Hello,

On 03.08.21 11:44, Rouven Czerwinski wrote:
> This allows the PBL to fill a reserved memory map which a subsequent
> commit will use modify the early MMU mapping.
> 
> Signed-off-by: Rouven Czerwinski <r.czerwinski@xxxxxxxxxxxxxx>
> ---
>  include/pbl.h |  25 ++++++++++++
>  pbl/fdt.c     | 103 ++++++++++++++++++++++++++++++++++++++++++--------
>  2 files changed, 113 insertions(+), 15 deletions(-)
> 
> diff --git a/include/pbl.h b/include/pbl.h
> index f58daec735..03272879d7 100644
> --- a/include/pbl.h
> +++ b/include/pbl.h
> @@ -42,5 +42,30 @@ struct fdt_device_id {
>  const void *
>  fdt_device_get_match_data(const void *fdt, const char *nodepath,
>  			  const struct fdt_device_id ids[]);
> +struct pbl_reserved_memory {
> +	phys_addr_t			base;
> +	phys_addr_t			size;
> +	unsigned int			flags;
> +};
> +
> +#define MAX_RESERVED_REGIONS	8
> +
> +#define FDT_RES_MEM_FLAG_NOMAP		BIT(0)
> +
> +void fdt_fill_reserve_mem(const void *fdt);
> +
> +#ifdef CONFIG_LIBFDT
> +const struct pbl_reserved_memory *get_pbl_reserved_memory(void);
> +int get_pbl_reserved_memory_num(void);
> +#else
> +static inline const struct pbl_reserved_memory *get_pbl_reserved_memory(void)
> +{
> +	return NULL;
> +}
> +static inline int get_pbl_reserved_memory_num(void)
> +{
> +	return 0;
> +}
> +#endif
>  
>  #endif /* __PBL_H__ */
> diff --git a/pbl/fdt.c b/pbl/fdt.c
> index 18ddb9f48a..383d0fec74 100644
> --- a/pbl/fdt.c
> +++ b/pbl/fdt.c
> @@ -5,8 +5,8 @@
>  
>  void fdt_find_mem(const void *fdt, unsigned long *membase, unsigned long *memsize)
>  {
> -	const __be32 *nap, *nsp, *reg;
> -	uint32_t na, ns;
> +	const __be32 *reg;
> +	int na, ns;
>  	uint64_t memsize64, membase64;
>  	int node, size, i;
>  
> @@ -16,26 +16,17 @@ void fdt_find_mem(const void *fdt, unsigned long *membase, unsigned long *memsiz
>  		goto err;
>  	}
>  
> -	/* Find the #address-cells and #size-cells properties */
> -	node = fdt_path_offset(fdt, "/");
> -	if (node < 0) {
> -		pr_err("Cannot find root node\n");
> -		goto err;
> -	}
> -
> -	nap = fdt_getprop(fdt, node, "#address-cells", &size);
> -	if (!nap || (size != 4)) {
> +	na = fdt_address_cells(fdt, 0);
> +	if (na < 0) {
>  		pr_err("Cannot find #address-cells property");
>  		goto err;
>  	}
> -	na = fdt32_to_cpu(*nap);
>  
> -	nsp = fdt_getprop(fdt, node, "#size-cells", &size);
> -	if (!nsp || (size != 4)) {
> +	ns = fdt_size_cells(fdt, 0);
> +	if (ns < 0) {
>  		pr_err("Cannot find #size-cells property");
>  		goto err;
>  	}
> -	ns = fdt32_to_cpu(*nap);

I like the simplification, but it looks unrelated to the early reserved mem support..?
Perhaps split it up?

>  
>  	/* Find the memory range */
>  	node = fdt_node_offset_by_prop_value(fdt, -1, "device_type",
> @@ -103,3 +94,85 @@ const void *fdt_device_get_match_data(const void *fdt, const char *nodepath,
>  
>  	return NULL;
>  }
> +
> +static struct pbl_reserved_memory reserved_mem[MAX_RESERVED_REGIONS];
> +static int reserved_mem_count;
> +
> +void fdt_fill_reserve_mem(const void *fdt)
> +{
> +	const __be32 *nap, *nsp, *reg;
> +	uint32_t na, ns;
> +	int node, size, i, parent;
> +	const void *prop;
> +	uint64_t memsize64, membase64;
> +	bool nomap;
> +
> +	/* Make sure FDT blob is sane */
> +	if (fdt_check_header(fdt) != 0) {
> +		pr_err("Invalid device tree blob\n");
> +		return;
> +	}
> +
> +	parent = fdt_path_offset(fdt, "/reserved-memory");
> +	if (parent < 0) {
> +		pr_info("Cannot find reserved-memory node\n");
> +		return;
> +	}
> +
> +	nap = fdt_getprop(fdt, parent, "#address-cells", &size);
> +	if (!nap || (size != 4)) {
> +		pr_err("Cannot find #address-cells property");
> +		return;
> +	}
> +	na = fdt32_to_cpu(*nap);
> +
> +	nsp = fdt_getprop(fdt, parent, "#size-cells", &size);
> +	if (!nsp || (size != 4)) {
> +		pr_err("Cannot find #size-cells property");
> +		return;
> +	}
> +	ns = fdt32_to_cpu(*nap);

Oh, did you mean to use the cool fdt_address_cells and fdt_size_cells helper you found here
but fuzzily wrote your code? ^^'

> +
> +	fdt_for_each_subnode(node, fdt, parent) {
> +		nomap = true;
> +		reg = fdt_getprop(fdt, node, "reg", &size);
> +		if (size < (na + ns) * sizeof(u32)) {
> +			pr_err("cannot get memory range\n");
> +			return;
> +		}
> +
> +		membase64 = 0;
> +		for (i = 0; i < na; i++)
> +			membase64 = (membase64 << 32) | fdt32_to_cpu(*reg++);
> +
> +		/* get the memsize and truncate it to under 4G on 32 bit machines */
> +		memsize64 = 0;
> +		for (i = 0; i < ns; i++)
> +			memsize64 = (memsize64 << 32) | fdt32_to_cpu(*reg++);

Can you turn this into a helper and use that for both fdt_find_mem and fdt_fill_reserve_mem?

> +
> +		prop = fdt_getprop(fdt, node, "nomap", NULL);
> +		if (!prop)
> +			nomap = false;

Nitpick:

 if (fdt_getprop(fdt, node, "nomap", NULL))
	reserved_mem[reserved_mem_count].flags |= FDT_RES_MEM_FLAG_NOMAP;

would've worked too. Neither prop or nomap is strictly needed.

> +
> +		reserved_mem[reserved_mem_count].base = membase64;
> +		reserved_mem[reserved_mem_count].size = memsize64;
> +		if (nomap)
> +			reserved_mem[reserved_mem_count].flags |= FDT_RES_MEM_FLAG_NOMAP;
> +		reserved_mem_count++;
> +	}
> +
> +	if ((node < 0) && (node != -FDT_ERR_NOTFOUND)) {
> +		pr_err("Error while parsing reserved-memory nodes: %d\n", node);
> +		return;
> +	}
> +}
> +
> +const struct pbl_reserved_memory *get_pbl_reserved_memory(void)
> +{
> +	return reserved_mem;
> +}
> +
> +int get_pbl_reserved_memory_num(void)
> +{
> +	return reserved_mem_count;
> +}
> 


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