drivers/firmware/efi/libstub/riscv.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2020 Western Digital Corporation or its affiliates.
   4  */
   5
   6 #include <linux/efi.h>
   7 #include <linux/libfdt.h>
   8
   9 #include <asm/efi.h>
  10 #include <linux/unaligned.h>
  11
  12 #include "efistub.h"
  13
  14 typedef void __noreturn (*jump_kernel_func)(unsigned long, unsigned long);
  15
  16 static unsigned long hartid;
  17
  18 static int get_boot_hartid_from_fdt(void)
  19 {
  20         const void *fdt;
  21         int chosen_node, len;
  22         const void *prop;
  23
  24         fdt = get_efi_config_table(DEVICE_TREE_GUID);
  25         if (!fdt)
  26                 return -EINVAL;
  27
  28         chosen_node = fdt_path_offset(fdt, "/chosen");
  29         if (chosen_node < 0)
  30                 return -EINVAL;
  31
  32         prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
  33         if (!prop)
  34                 return -EINVAL;
  35
  36         if (len == sizeof(u32))
  37                 hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
  38         else if (len == sizeof(u64))
  39                 hartid = (unsigned long) fdt64_to_cpu(__get_unaligned_t(fdt64_t, prop));
  40         else
  41                 return -EINVAL;
  42
  43         return 0;
  44 }
  45
  46 static efi_status_t get_boot_hartid_from_efi(void)
  47 {
  48         efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
  49         struct riscv_efi_boot_protocol *boot_protocol;
  50         efi_status_t status;
  51
  52         status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
  53                              (void **)&boot_protocol);
  54         if (status != EFI_SUCCESS)
  55                 return status;
  56         return efi_call_proto(boot_protocol, get_boot_hartid, &hartid);
  57 }
  58
  59 efi_status_t check_platform_features(void)
  60 {
  61         efi_status_t status;
  62         int ret;
  63
  64         status = get_boot_hartid_from_efi();
  65         if (status != EFI_SUCCESS) {
  66                 ret = get_boot_hartid_from_fdt();
  67                 if (ret) {
  68                         efi_err("Failed to get boot hartid!\n");
  69                         return EFI_UNSUPPORTED;
  70                 }
  71         }
  72         return EFI_SUCCESS;
  73 }
  74
  75 unsigned long __weak stext_offset(void)
  76 {
  77         /*
  78          * This fallback definition is used by the EFI zboot stub, which loads
  79          * the entire image so it can branch via the image header at offset #0.
  80          */
  81         return 0;
  82 }
  83
  84 void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
  85                                  unsigned long fdt_size)
  86 {
  87         unsigned long kernel_entry = entrypoint + stext_offset();
  88         jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
  89
  90         /*
  91          * Jump to real kernel here with following constraints.
  92          * 1. MMU should be disabled.
  93          * 2. a0 should contain hartid
  94          * 3. a1 should DT address
  95          */
  96         csr_write(CSR_SATP, 0);
  97         jump_kernel(hartid, fdt);
  98 }