lib/efi_loader/helloworld.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * EFI hello world
   4  *
   5  * Copyright (c) 2016 Google, Inc
   6  * Written by Simon Glass <sjg@chromium.org>
   7  *
   8  * This program demonstrates calling a boottime service.
   9  * It writes a greeting and the load options to the console.
  10  */
  11
  12 #include <common.h>
  13 #include <efi_api.h>
  14
  15 static const efi_guid_t loaded_image_guid = LOADED_IMAGE_GUID;
  16 static const efi_guid_t fdt_guid = EFI_FDT_GUID;
  17 static const efi_guid_t acpi_guid = EFI_ACPI_TABLE_GUID;
  18 static const efi_guid_t smbios_guid = SMBIOS_TABLE_GUID;
  19
  20 /**
  21  * hw_memcmp() - compare memory areas
  22  *
  23  * @buf1:       pointer to first area
  24  * @buf2:       pointer to second area
  25  * @length:     number of bytes to compare
  26  * Return:      0 if both memory areas are the same, otherwise the sign of the
  27  *              result value is the same as the sign of ghe difference between
  28  *              the first differing pair of bytes taken as u8.
  29  */
  30 static int hw_memcmp(const void *buf1, const void *buf2, size_t length)
  31 {
  32         const u8 *pos1 = buf1;
  33         const u8 *pos2 = buf2;
  34
  35         for (; length; --length) {
  36                 if (*pos1 != *pos2)
  37                         return *pos1 - *pos2;
  38                 ++pos1;
  39                 ++pos2;
  40         }
  41         return 0;
  42 }
  43
  44 /**
  45  * efi_main() - entry point of the EFI application.
  46  *
  47  * @handle:     handle of the loaded image
  48  * @systable:   system table
  49  * @return:     status code
  50  */
  51 efi_status_t EFIAPI efi_main(efi_handle_t handle,
  52                              struct efi_system_table *systable)
  53 {
  54         struct efi_simple_text_output_protocol *con_out = systable->con_out;
  55         struct efi_boot_services *boottime = systable->boottime;
  56         struct efi_loaded_image *loaded_image;
  57         efi_status_t ret;
  58         efi_uintn_t i;
  59         u16 rev[] = L"0.0.0";
  60
  61         /* UEFI requires CR LF */
  62         con_out->output_string(con_out, L"Hello, world!\r\n");
  63
  64         /* Print the revision number */
  65         rev[0] = (systable->hdr.revision >> 16) + '0';
  66         rev[4] = systable->hdr.revision & 0xffff;
  67         for (; rev[4] >= 10;) {
  68                 rev[4] -= 10;
  69                 ++rev[2];
  70         }
  71         /* Third digit is only to be shown if non-zero */
  72         if (rev[4])
  73                 rev[4] += '0';
  74         else
  75                 rev[3] = 0;
  76
  77         con_out->output_string(con_out, L"Running on UEFI ");
  78         con_out->output_string(con_out, rev);
  79         con_out->output_string(con_out, L"\r\n");
  80
  81         /* Get the loaded image protocol */
  82         ret = boottime->handle_protocol(handle, &loaded_image_guid,
  83                                         (void **)&loaded_image);
  84         if (ret != EFI_SUCCESS) {
  85                 con_out->output_string
  86                         (con_out, L"Cannot open loaded image protocol\r\n");
  87                 goto out;
  88         }
  89         /* Find configuration tables */
  90         for (i = 0; i < systable->nr_tables; ++i) {
  91                 if (!hw_memcmp(&systable->tables[i].guid, &fdt_guid,
  92                                sizeof(efi_guid_t)))
  93                         con_out->output_string
  94                                         (con_out, L"Have device tree\r\n");
  95                 if (!hw_memcmp(&systable->tables[i].guid, &acpi_guid,
  96                                sizeof(efi_guid_t)))
  97                         con_out->output_string
  98                                         (con_out, L"Have ACPI 2.0 table\r\n");
  99                 if (!hw_memcmp(&systable->tables[i].guid, &smbios_guid,
 100                                sizeof(efi_guid_t)))
 101                         con_out->output_string
 102                                         (con_out, L"Have SMBIOS table\r\n");
 103         }
 104         /* Output the load options */
 105         con_out->output_string(con_out, L"Load options: ");
 106         if (loaded_image->load_options_size && loaded_image->load_options)
 107                 con_out->output_string(con_out,
 108                                        (u16 *)loaded_image->load_options);
 109         else
 110                 con_out->output_string(con_out, L"<none>");
 111         con_out->output_string(con_out, L"\r\n");
 112
 113 out:
 114         boottime->exit(handle, ret, 0, NULL);
 115
 116         /* We should never arrive here */
 117         return ret;
 118 }