Commit 0302f71c authored by Mark Salter's avatar Mark Salter Committed by Matt Fleming
Browse files

efi: add helper function to get UEFI params from FDT 



ARM and ARM64 architectures use the device tree to pass UEFI parameters
from stub to kernel. These parameters are things known to the stub but
not discoverable by the kernel after the stub calls ExitBootSerives().
There is a helper function in:

   drivers/firmware/efi/fdt.c

which the stub uses to add the UEFI parameters to the device tree.
This patch adds a complimentary helper function which UEFI runtime
support may use to retrieve the parameters from the device tree.
If an architecture wants to use this helper, it should select
CONFIG_EFI_PARAMS_FROM_FDT.

Signed-off-by: default avatarMark Salter <msalter@redhat.com>
Signed-off-by: default avatarLeif Lindholm <leif.lindholm@linaro.org>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
parent 719e2843

drivers/firmware/efi/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -47,6 +47,13 @@ config EFI_RUNTIME_MAP 


	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.



config EFI_PARAMS_FROM_FDT

	bool

	help

	  Select this config option from the architecture Kconfig if

	  the EFI runtime support gets system table address, memory

          map address, and other parameters from the device tree.



endmenu



config UEFI_CPER

drivers/firmware/efi/efi.c

+79 −0
Original line number Diff line number Diff line
@@ -20,6 +20,8 @@ 
#include <linux/init.h>

#include <linux/device.h>

#include <linux/efi.h>

#include <linux/of.h>

#include <linux/of_fdt.h>

#include <linux/io.h>



struct efi __read_mostly efi = {
@@ -318,3 +320,80 @@ int __init efi_config_init(efi_config_table_type_t *arch_tables) 


	return 0;

}



#ifdef CONFIG_EFI_PARAMS_FROM_FDT



#define UEFI_PARAM(name, prop, field)			   \

	{						   \

		{ name },				   \

		{ prop },				   \

		offsetof(struct efi_fdt_params, field),    \

		FIELD_SIZEOF(struct efi_fdt_params, field) \

	}



static __initdata struct {

	const char name[32];

	const char propname[32];

	int offset;

	int size;

} dt_params[] = {

	UEFI_PARAM("System Table", "linux,uefi-system-table", system_table),

	UEFI_PARAM("MemMap Address", "linux,uefi-mmap-start", mmap),

	UEFI_PARAM("MemMap Size", "linux,uefi-mmap-size", mmap_size),

	UEFI_PARAM("MemMap Desc. Size", "linux,uefi-mmap-desc-size", desc_size),

	UEFI_PARAM("MemMap Desc. Version", "linux,uefi-mmap-desc-ver", desc_ver)

};



struct param_info {

	int verbose;

	void *params;

};



static int __init fdt_find_uefi_params(unsigned long node, const char *uname,

				       int depth, void *data)

{

	struct param_info *info = data;

	void *prop, *dest;

	unsigned long len;

	u64 val;

	int i;



	if (depth != 1 ||

	    (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))

		return 0;



	pr_info("Getting parameters from FDT:\n");



	for (i = 0; i < ARRAY_SIZE(dt_params); i++) {

		prop = of_get_flat_dt_prop(node, dt_params[i].propname, &len);

		if (!prop) {

			pr_err("Can't find %s in device tree!\n",

			       dt_params[i].name);

			return 0;

		}

		dest = info->params + dt_params[i].offset;



		val = of_read_number(prop, len / sizeof(u32));



		if (dt_params[i].size == sizeof(u32))

			*(u32 *)dest = val;

		else

			*(u64 *)dest = val;



		if (info->verbose)

			pr_info("  %s: 0x%0*llx\n", dt_params[i].name,

				dt_params[i].size * 2, val);

	}

	return 1;

}



int __init efi_get_fdt_params(struct efi_fdt_params *params, int verbose)

{

	struct param_info info;



	info.verbose = verbose;

	info.params = params;



	return of_scan_flat_dt(fdt_find_uefi_params, &info);

}

#endif /* CONFIG_EFI_PARAMS_FROM_FDT */

include/linux/efi.h

+9 −0
Original line number Diff line number Diff line
@@ -664,6 +664,14 @@ struct efi_memory_map { 
	unsigned long desc_size;

};



struct efi_fdt_params {

	u64 system_table;

	u64 mmap;

	u32 mmap_size;

	u32 desc_size;

	u32 desc_ver;

};



typedef struct {

	u32 revision;

	u32 parent_handle;
@@ -861,6 +869,7 @@ extern void efi_initialize_iomem_resources(struct resource *code_resource, 
extern void efi_get_time(struct timespec *now);

extern int efi_set_rtc_mmss(const struct timespec *now);

extern void efi_reserve_boot_services(void);

extern int efi_get_fdt_params(struct efi_fdt_params *params, int verbose);

extern struct efi_memory_map memmap;



/* Iterate through an efi_memory_map */

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