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 } 119