drivers/firmware/efi/libstub/riscv-stub.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 <asm/sections.h>
  11
  12 #include "efistub.h"
  13
  14 /*
  15  * RISC-V requires the kernel image to placed 2 MB aligned base for 64 bit and
  16  * 4MB for 32 bit.
  17  */
  18 #ifdef CONFIG_64BIT
  19 #define MIN_KIMG_ALIGN          SZ_2M
  20 #else
  21 #define MIN_KIMG_ALIGN          SZ_4M
  22 #endif
  23
  24 typedef void __noreturn (*jump_kernel_func)(unsigned long, unsigned long);
  25
  26 static unsigned long hartid;
  27
  28 static int get_boot_hartid_from_fdt(void)
  29 {
  30         const void *fdt;
  31         int chosen_node, len;
  32         const fdt32_t *prop;
  33
  34         fdt = get_efi_config_table(DEVICE_TREE_GUID);
  35         if (!fdt)
  36                 return -EINVAL;
  37
  38         chosen_node = fdt_path_offset(fdt, "/chosen");
  39         if (chosen_node < 0)
  40                 return -EINVAL;
  41
  42         prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
  43         if (!prop || len != sizeof(u32))
  44                 return -EINVAL;
  45
  46         hartid = fdt32_to_cpu(*prop);
  47         return 0;
  48 }
  49
  50 static efi_status_t get_boot_hartid_from_efi(void)
  51 {
  52         efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
  53         struct riscv_efi_boot_protocol *boot_protocol;
  54         efi_status_t status;
  55
  56         status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
  57                              (void **)&boot_protocol);
  58         if (status != EFI_SUCCESS)
  59                 return status;
  60         return efi_call_proto(boot_protocol, get_boot_hartid, &hartid);
  61 }
  62
  63 efi_status_t check_platform_features(void)
  64 {
  65         efi_status_t status;
  66         int ret;
  67
  68         status = get_boot_hartid_from_efi();
  69         if (status != EFI_SUCCESS) {
  70                 ret = get_boot_hartid_from_fdt();
  71                 if (ret) {
  72                         efi_err("Failed to get boot hartid!\n");
  73                         return EFI_UNSUPPORTED;
  74                 }
  75         }
  76         return EFI_SUCCESS;
  77 }
  78
  79 void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
  80                                  unsigned long fdt_size)
  81 {
  82         unsigned long stext_offset = _start_kernel - _start;
  83         unsigned long kernel_entry = entrypoint + stext_offset;
  84         jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
  85
  86         /*
  87          * Jump to real kernel here with following constraints.
  88          * 1. MMU should be disabled.
  89          * 2. a0 should contain hartid
  90          * 3. a1 should DT address
  91          */
  92         csr_write(CSR_SATP, 0);
  93         jump_kernel(hartid, fdt);
  94 }
  95
  96 efi_status_t handle_kernel_image(unsigned long *image_addr,
  97                                  unsigned long *image_size,
  98                                  unsigned long *reserve_addr,
  99                                  unsigned long *reserve_size,
 100                                  efi_loaded_image_t *image,
 101                                  efi_handle_t image_handle)
 102 {
 103         unsigned long kernel_size = 0;
 104         unsigned long preferred_addr;
 105         efi_status_t status;
 106
 107         kernel_size = _edata - _start;
 108         *image_addr = (unsigned long)_start;
 109         *image_size = kernel_size + (_end - _edata);
 110
 111         /*
 112          * RISC-V kernel maps PAGE_OFFSET virtual address to the same physical
 113          * address where kernel is booted. That's why kernel should boot from
 114          * as low as possible to avoid wastage of memory. Currently, dram_base
 115          * is occupied by the firmware. So the preferred address for kernel to
 116          * boot is next aligned address. If preferred address is not available,
 117          * relocate_kernel will fall back to efi_low_alloc_above to allocate
 118          * lowest possible memory region as long as the address and size meets
 119          * the alignment constraints.
 120          */
 121         preferred_addr = MIN_KIMG_ALIGN;
 122         status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
 123                                      preferred_addr, MIN_KIMG_ALIGN, 0x0);
 124
 125         if (status != EFI_SUCCESS) {
 126                 efi_err("Failed to relocate kernel\n");
 127                 *image_size = 0;
 128         }
 129         return status;
 130 }