Commit 2af2b50a authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Rob Herring
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of: fdt: Add generic support for handling usable memory range property 



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: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: default avatarRob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/3bd69bada93ee59b7d23c38b3527fc1654e19343.1628670468.git.geert+renesas@glider.be
parent f7e7ce93

Documentation/devicetree/bindings/chosen.txt

+3 −3
Original line number Diff line number Diff line
@@ -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

drivers/of/fdt.c

+30 −0
Original line number Diff line number Diff line
@@ -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)