[PATCH v4 04/10] of: fdt: Add generic support for parsing usable memory range property
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: 2021-07-14 12:51:03
Also in:
kexec, linux-arm-kernel, linux-mm, linux-renesas-soc, linux-riscv, lkml
Subsystem:
open firmware and flattened device tree, open firmware and flattened device tree bindings, the rest · Maintainers:
Rob Herring, Saravana Kannan, Krzysztof Kozlowski, Conor Dooley, Linus Torvalds
Add support for parsing the "linux,usable-memory-range" property in the "/chosen" node to the FDT core code. This can co-exist safely with the architecture-specific parsing, until the latter has been removed. Architecture-specific code still has to make sure the resulting memory range limitation is applied, if present. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- About the change to chosen.txt: I have a similar change for schemas/chosen.yaml in dt-schema. v4: - New. --- Documentation/devicetree/bindings/chosen.txt | 6 ++--- drivers/of/fdt.c | 24 ++++++++++++++++++++ 2 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 5b0b94eb2d04e79d..1cc3aa10dcb10588 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt@@ -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
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index f797d52c5b492cb7..1b4dd5418b44b9fb 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c@@ -935,6 +935,29 @@ static void __init early_init_dt_check_for_elfcorehdr(unsigned long node) elfcorehdr_addr, elfcorehdr_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)
@@ -1083,6 +1106,7 @@ 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);
--
2.25.1