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Diffstat (limited to 'drivers/firmware/efi/fdtparams.c')
-rw-r--r--drivers/firmware/efi/fdtparams.c133
1 files changed, 133 insertions, 0 deletions
diff --git a/drivers/firmware/efi/fdtparams.c b/drivers/firmware/efi/fdtparams.c
new file mode 100644
index 0000000000..0ec83ba580
--- /dev/null
+++ b/drivers/firmware/efi/fdtparams.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt) "efi: " fmt
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/efi.h>
+#include <linux/libfdt.h>
+#include <linux/of_fdt.h>
+
+#include <asm/unaligned.h>
+
+enum {
+ SYSTAB,
+ MMBASE,
+ MMSIZE,
+ DCSIZE,
+ DCVERS,
+
+ PARAMCOUNT
+};
+
+static __initconst const char name[][22] = {
+ [SYSTAB] = "System Table ",
+ [MMBASE] = "MemMap Address ",
+ [MMSIZE] = "MemMap Size ",
+ [DCSIZE] = "MemMap Desc. Size ",
+ [DCVERS] = "MemMap Desc. Version ",
+};
+
+static __initconst const struct {
+ const char path[17];
+ u8 paravirt;
+ const char params[PARAMCOUNT][26];
+} dt_params[] = {
+ {
+#ifdef CONFIG_XEN // <-------17------>
+ .path = "/hypervisor/uefi",
+ .paravirt = 1,
+ .params = {
+ [SYSTAB] = "xen,uefi-system-table",
+ [MMBASE] = "xen,uefi-mmap-start",
+ [MMSIZE] = "xen,uefi-mmap-size",
+ [DCSIZE] = "xen,uefi-mmap-desc-size",
+ [DCVERS] = "xen,uefi-mmap-desc-ver",
+ }
+ }, {
+#endif
+ .path = "/chosen",
+ .params = { // <-----------26----------->
+ [SYSTAB] = "linux,uefi-system-table",
+ [MMBASE] = "linux,uefi-mmap-start",
+ [MMSIZE] = "linux,uefi-mmap-size",
+ [DCSIZE] = "linux,uefi-mmap-desc-size",
+ [DCVERS] = "linux,uefi-mmap-desc-ver",
+ }
+ }
+};
+
+static int __init efi_get_fdt_prop(const void *fdt, int node, const char *pname,
+ const char *rname, void *var, int size)
+{
+ const void *prop;
+ int len;
+ u64 val;
+
+ prop = fdt_getprop(fdt, node, pname, &len);
+ if (!prop)
+ return 1;
+
+ val = (len == 4) ? (u64)be32_to_cpup(prop) : get_unaligned_be64(prop);
+
+ if (size == 8)
+ *(u64 *)var = val;
+ else
+ *(u32 *)var = (val < U32_MAX) ? val : U32_MAX; // saturate
+
+ if (efi_enabled(EFI_DBG))
+ pr_info(" %s: 0x%0*llx\n", rname, size * 2, val);
+
+ return 0;
+}
+
+u64 __init efi_get_fdt_params(struct efi_memory_map_data *mm)
+{
+ const void *fdt = initial_boot_params;
+ unsigned long systab;
+ int i, j, node;
+ struct {
+ void *var;
+ int size;
+ } target[] = {
+ [SYSTAB] = { &systab, sizeof(systab) },
+ [MMBASE] = { &mm->phys_map, sizeof(mm->phys_map) },
+ [MMSIZE] = { &mm->size, sizeof(mm->size) },
+ [DCSIZE] = { &mm->desc_size, sizeof(mm->desc_size) },
+ [DCVERS] = { &mm->desc_version, sizeof(mm->desc_version) },
+ };
+
+ BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(name));
+ BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(dt_params[0].params));
+
+ if (!fdt)
+ return 0;
+
+ for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
+ node = fdt_path_offset(fdt, dt_params[i].path);
+ if (node < 0)
+ continue;
+
+ if (efi_enabled(EFI_DBG))
+ pr_info("Getting UEFI parameters from %s in DT:\n",
+ dt_params[i].path);
+
+ for (j = 0; j < ARRAY_SIZE(target); j++) {
+ const char *pname = dt_params[i].params[j];
+
+ if (!efi_get_fdt_prop(fdt, node, pname, name[j],
+ target[j].var, target[j].size))
+ continue;
+ if (!j)
+ goto notfound;
+ pr_err("Can't find property '%s' in DT!\n", pname);
+ return 0;
+ }
+ if (dt_params[i].paravirt)
+ set_bit(EFI_PARAVIRT, &efi.flags);
+ return systab;
+ }
+notfound:
+ pr_info("UEFI not found.\n");
+ return 0;
+}