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1// SPDX-License-Identifier: GPL-2.02/*3 * Export Runtime Configuration Interface Table Version 2 (RCI2)4 * to sysfs5 *6 * Copyright (C) 2019 Dell Inc7 * by Narendra K <Narendra.K@dell.com>8 *9 * System firmware advertises the address of the RCI2 Table via10 * an EFI Configuration Table entry. This code retrieves the RCI211 * table from the address and exports it to sysfs as a binary12 * attribute 'rci2' under /sys/firmware/efi/tables directory.13 */14 15#include <linux/kobject.h>16#include <linux/device.h>17#include <linux/sysfs.h>18#include <linux/efi.h>19#include <linux/types.h>20#include <linux/io.h>21 22#define RCI_SIGNATURE "_RC_"23 24struct rci2_table_global_hdr {25 u16 type;26 u16 resvd0;27 u16 hdr_len;28 u8 rci2_sig[4];29 u16 resvd1;30 u32 resvd2;31 u32 resvd3;32 u8 major_rev;33 u8 minor_rev;34 u16 num_of_structs;35 u32 rci2_len;36 u16 rci2_chksum;37} __packed;38 39static u8 *rci2_base;40static u32 rci2_table_len;41unsigned long rci2_table_phys __ro_after_init = EFI_INVALID_TABLE_ADDR;42 43static BIN_ATTR_SIMPLE_ADMIN_RO(rci2);44 45static u16 checksum(void)46{47 u8 len_is_odd = rci2_table_len % 2;48 u32 chksum_len = rci2_table_len;49 u16 *base = (u16 *)rci2_base;50 u8 buf[2] = {0};51 u32 offset = 0;52 u16 chksum = 0;53 54 if (len_is_odd)55 chksum_len -= 1;56 57 while (offset < chksum_len) {58 chksum += *base;59 offset += 2;60 base++;61 }62 63 if (len_is_odd) {64 buf[0] = *(u8 *)base;65 chksum += *(u16 *)(buf);66 }67 68 return chksum;69}70 71static int __init efi_rci2_sysfs_init(void)72{73 struct kobject *tables_kobj;74 int ret = -ENOMEM;75 76 if (rci2_table_phys == EFI_INVALID_TABLE_ADDR)77 return 0;78 79 rci2_base = memremap(rci2_table_phys,80 sizeof(struct rci2_table_global_hdr),81 MEMREMAP_WB);82 if (!rci2_base) {83 pr_debug("RCI2 table init failed - could not map RCI2 table\n");84 goto err;85 }86 87 if (strncmp(rci2_base +88 offsetof(struct rci2_table_global_hdr, rci2_sig),89 RCI_SIGNATURE, 4)) {90 pr_debug("RCI2 table init failed - incorrect signature\n");91 ret = -ENODEV;92 goto err_unmap;93 }94 95 rci2_table_len = *(u32 *)(rci2_base +96 offsetof(struct rci2_table_global_hdr,97 rci2_len));98 99 memunmap(rci2_base);100 101 if (!rci2_table_len) {102 pr_debug("RCI2 table init failed - incorrect table length\n");103 goto err;104 }105 106 rci2_base = memremap(rci2_table_phys, rci2_table_len, MEMREMAP_WB);107 if (!rci2_base) {108 pr_debug("RCI2 table - could not map RCI2 table\n");109 goto err;110 }111 112 if (checksum() != 0) {113 pr_debug("RCI2 table - incorrect checksum\n");114 ret = -ENODEV;115 goto err_unmap;116 }117 118 tables_kobj = kobject_create_and_add("tables", efi_kobj);119 if (!tables_kobj) {120 pr_debug("RCI2 table - tables_kobj creation failed\n");121 goto err_unmap;122 }123 124 bin_attr_rci2.size = rci2_table_len;125 bin_attr_rci2.private = rci2_base;126 ret = sysfs_create_bin_file(tables_kobj, &bin_attr_rci2);127 if (ret != 0) {128 pr_debug("RCI2 table - rci2 sysfs bin file creation failed\n");129 kobject_del(tables_kobj);130 kobject_put(tables_kobj);131 goto err_unmap;132 }133 134 return 0;135 136 err_unmap:137 memunmap(rci2_base);138 err:139 pr_debug("RCI2 table - sysfs initialization failed\n");140 return ret;141}142late_initcall(efi_rci2_sysfs_init);143