[1/2] common: memtop: add logic to detect ram_top

Add generic logic to determine the ram_top value for boards. Earlier,
this was achieved in an indirect manner through a set of LMB API's.
That has since changed so that the LMB code is available only after
relocation. Replace those LMB calls with a single call to
get_mem_top() to determine the value of ram_top.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
---
 common/Makefile  |   1 +
 common/memtop.c  | 186 +++++++++++++++++++++++++++++++++++++++++++++++
 include/memtop.h |  22 ++++++
 3 files changed, 209 insertions(+)
 create mode 100644 common/memtop.c
 create mode 100644 include/memtop.h

On 10/25/24 14:15, Sughosh Ganu wrote:
> Add generic logic to determine the ram_top value for boards. Earlier,
> this was achieved in an indirect manner through a set of LMB API's.
> That has since changed so that the LMB code is available only after
> relocation. Replace those LMB calls with a single call to
> get_mem_top() to determine the value of ram_top.
> 
> Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
> ---
>   common/Makefile  |   1 +
>   common/memtop.c  | 186 +++++++++++++++++++++++++++++++++++++++++++++++
>   include/memtop.h |  22 ++++++
>   3 files changed, 209 insertions(+)
>   create mode 100644 common/memtop.c
>   create mode 100644 include/memtop.h
> 
> diff --git a/common/Makefile b/common/Makefile
> index 2ee5ef9cc6e..35991562a12 100644
> --- a/common/Makefile
> +++ b/common/Makefile
> @@ -7,6 +7,7 @@
>   ifndef CONFIG_XPL_BUILD
>   obj-y += init/
>   obj-y += main.o
> +obj-y += memtop.o
>   obj-y += exports.o
>   obj-y += cli_getch.o cli_simple.o cli_readline.o
>   obj-$(CONFIG_HUSH_OLD_PARSER) += cli_hush.o
> diff --git a/common/memtop.c b/common/memtop.c
> new file mode 100644
> index 00000000000..579daa89136
> --- /dev/null
> +++ b/common/memtop.c
> @@ -0,0 +1,186 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) 2024, Linaro Limited
> + */
> +
> +#include <fdt_support.h>
> +#include <fdtdec.h>
> +#include <memtop.h>
> +
> +#include <asm/types.h>
> +
> +#define MEM_RGN_COUNT	16
> +
> +struct region {
> +	phys_addr_t base;
> +	phys_size_t size;
> +};
> +
> +struct mem_region {
> +	struct region rgn[MEM_RGN_COUNT];
> +	uint count;
> +};
> +
> +static void add_mem_region(struct mem_region *mem_rgn, phys_addr_t base,
> +			   phys_size_t size)
> +{
> +	long i;
> +
> +	for (i = mem_rgn->count; i >= 0; i--) {
> +		if (i && base < mem_rgn->rgn[i - 1].base) {
> +			mem_rgn->rgn[i] = mem_rgn->rgn[i - 1];
> +		} else {
> +			mem_rgn->rgn[i].base = base;
> +			mem_rgn->rgn[i].size = size;
> +			break;
> +		}
> +	}
> +
> +	mem_rgn->count++;
> +}
> +
> +static void mem_regions_init(struct mem_region *mem)
> +{
> +	uint i;
> +
> +	mem->count = 0;
> +	for (i = 0; i < MEM_RGN_COUNT; i++) {
> +		mem->rgn[i].base = 0;
> +		mem->rgn[i].size = 0;
> +	}
> +}
> +
> +static int fdt_add_reserved_regions(struct mem_region *free_mem,
> +				    struct mem_region *reserved_mem,
> +				    void *fdt_blob)
> +{
> +	u64 addr, size;
> +	int i, total, ret;
> +	int nodeoffset, subnode;
> +	struct fdt_resource res;
> +
> +	if (fdt_check_header(fdt_blob) != 0)
> +		return -1;
> +
> +	/* process memreserve sections */
> +	total = fdt_num_mem_rsv(fdt_blob);
> +	assert_noisy(total < MEM_RGN_COUNT);
> +	for (i = 0; i < total; i++) {
> +		if (fdt_get_mem_rsv(fdt_blob, i, &addr, &size) != 0)
> +			continue;
> +		add_mem_region(reserved_mem, addr, size);
> +	}
> +
> +	i = 0;
> +	/* process reserved-memory */
> +	nodeoffset = fdt_subnode_offset(fdt_blob, 0, "reserved-memory");
> +	if (nodeoffset >= 0) {
> +		subnode = fdt_first_subnode(fdt_blob, nodeoffset);
> +		while (subnode >= 0) {
> +			/* check if this subnode has a reg property */
> +			ret = fdt_get_resource(fdt_blob, subnode, "reg", 0,
> +					       &res);
> +			if (!ret && fdtdec_get_is_enabled(fdt_blob, subnode)) {
> +				addr = res.start;
> +				size = res.end - res.start + 1;
> +				assert_noisy(i < MEM_RGN_COUNT);
> +				add_mem_region(reserved_mem, addr, size);
> +			}
> +
> +			subnode = fdt_next_subnode(fdt_blob, subnode);
> +			++i;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static long addrs_overlap(phys_addr_t base1, phys_size_t size1,
> +			  phys_addr_t base2, phys_size_t size2)
> +{
> +	const phys_addr_t base1_end = base1 + size1 - 1;
> +	const phys_addr_t base2_end = base2 + size2 - 1;
> +
> +	return ((base1 <= base2_end) && (base2 <= base1_end));
> +}
> +
> +static long region_overlap_check(struct mem_region *mem_rgn, phys_addr_t base,
> +				 phys_size_t size)
> +{
> +	unsigned long i;
> +	struct region *rgn = mem_rgn->rgn;
> +
> +	for (i = 0; i < mem_rgn->count; i++) {
> +		phys_addr_t rgnbase = rgn[i].base;
> +		phys_size_t rgnsize = rgn[i].size;
> +
> +		if (addrs_overlap(base, size, rgnbase, rgnsize))
> +			break;
> +	}
> +
> +	return (i < mem_rgn->count) ? i : -1;
> +}
> +
> +static int find_ram_top(struct mem_region *free_mem,
> +			struct mem_region *reserved_mem, phys_size_t size)
> +{
> +	long i, rgn;
> +	phys_addr_t base = 0;
> +	phys_addr_t res_base;
> +
> +	for (i = free_mem->count - 1; i >= 0; i--) {
> +		phys_addr_t rgnbase = free_mem->rgn[i].base;
> +		phys_size_t rgnsize = free_mem->rgn[i].size;
> +
> +		if (rgnsize < size)
> +			continue;
> +
> +		base = rgnbase + rgnsize - size;
> +		while (base && rgnbase <= base) {
> +			rgn = region_overlap_check(reserved_mem, base, size);
> +			if (rgn < 0)
> +				return base;
> +
> +			res_base = reserved_mem->rgn[rgn].base;
> +			if (res_base < size)
> +				break;
> +			base = res_base - size;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * get_mem_top() - Compute the value of ram_top
> + * @ram_start:	Start of RAM
> + * @ram_size:	RAM size
> + * @size:	Minimum RAM size requested
> + * @fdt:	FDT blob
> + *
> + * The function computes the top address of RAM memory that can be
> + * used by U-Boot. This is being done by going through the list of
> + * reserved memory regions specified in the devicetree blob passed
> + * to the function. The logic used here is derived from the lmb
> + * allocation function.
> + *
> + * Return: address of ram top on success, 0 on failure
> + */

There is likely no reason to have documentation written twice.
Using in just header should be fine.
When this is fixed feel free to add

Reviewed-by: Michal Simek <michal.simek@amd.com>

Thanks,
Michal