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of: fdt: Add generic support for handling usable memory range property

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Add support for handling the "linux,usable-memory-range" property in the
"/chosen" node to the FDT core code.  This can co-exist safely with the
architecture-specific handling, until the latter has been removed.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/3bd69bada93ee59b7d23c38b3527fc1654e19343.1628670468.git.geert+renesas@glider.be
This commit is contained in:
Geert Uytterhoeven 2021-08-11 10:51:02 +02:00 committed by Rob Herring
parent f7e7ce93aa
commit 2af2b50acf
2 changed files with 33 additions and 3 deletions
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6
Documentation/devicetree/bindings/chosen.txt
View File

@ -79,9 +79,9 @@ a different secondary CPU release mechanism)
linux,usable-memory-range
-------------------------
This property (arm64 only) holds a base address and size, describing a
limited region in which memory may be considered available for use by
the kernel. Memory outside of this range is not available for use.
This property holds a base address and size, describing a limited region in
which memory may be considered available for use by the kernel. Memory outside
of this range is not available for use.
This property describes a limitation: memory within this range is only
valid when also described through another mechanism that the kernel

30
drivers/of/fdt.c
View File

@ -972,6 +972,32 @@ static void __init early_init_dt_check_for_elfcorehdr(unsigned long node)
elfcorehdr_addr, elfcorehdr_size);
}
static phys_addr_t cap_mem_addr;
static phys_addr_t cap_mem_size;
/**
* early_init_dt_check_for_usable_mem_range - Decode usable memory range
* location from flat tree
* @node: reference to node containing usable memory range location ('chosen')
*/
static void __init early_init_dt_check_for_usable_mem_range(unsigned long node)
{
const __be32 *prop;
int len;
pr_debug("Looking for usable-memory-range property... ");
prop = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len);
if (!prop || (len < (dt_root_addr_cells + dt_root_size_cells)))
return;
cap_mem_addr = dt_mem_next_cell(dt_root_addr_cells, &prop);
cap_mem_size = dt_mem_next_cell(dt_root_size_cells, &prop);
pr_debug("cap_mem_start=%pa cap_mem_size=%pa\n", &cap_mem_addr,
&cap_mem_size);
}
#ifdef CONFIG_SERIAL_EARLYCON
int __init early_init_dt_scan_chosen_stdout(void)
@ -1120,6 +1146,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
early_init_dt_check_for_initrd(node);
early_init_dt_check_for_elfcorehdr(node);
early_init_dt_check_for_usable_mem_range(node);
/* Retrieve command line */
p = of_get_flat_dt_prop(node, "bootargs", &l);
@ -1253,6 +1280,9 @@ void __init early_init_dt_scan_nodes(void)
/* Setup memory, calling early_init_dt_add_memory_arch */
of_scan_flat_dt(early_init_dt_scan_memory, NULL);
/* Handle linux,usable-memory-range property */
memblock_cap_memory_range(cap_mem_addr, cap_mem_size);
}
bool __init early_init_dt_scan(void *params)