1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Export Runtime Configuration Interface Table Version 2 (RCI2)
4*4882a593Smuzhiyun * to sysfs
5*4882a593Smuzhiyun *
6*4882a593Smuzhiyun * Copyright (C) 2019 Dell Inc
7*4882a593Smuzhiyun * by Narendra K <Narendra.K@dell.com>
8*4882a593Smuzhiyun *
9*4882a593Smuzhiyun * System firmware advertises the address of the RCI2 Table via
10*4882a593Smuzhiyun * an EFI Configuration Table entry. This code retrieves the RCI2
11*4882a593Smuzhiyun * table from the address and exports it to sysfs as a binary
12*4882a593Smuzhiyun * attribute 'rci2' under /sys/firmware/efi/tables directory.
13*4882a593Smuzhiyun */
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun #include <linux/kobject.h>
16*4882a593Smuzhiyun #include <linux/device.h>
17*4882a593Smuzhiyun #include <linux/sysfs.h>
18*4882a593Smuzhiyun #include <linux/efi.h>
19*4882a593Smuzhiyun #include <linux/types.h>
20*4882a593Smuzhiyun #include <linux/io.h>
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun #define RCI_SIGNATURE "_RC_"
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun struct rci2_table_global_hdr {
25*4882a593Smuzhiyun u16 type;
26*4882a593Smuzhiyun u16 resvd0;
27*4882a593Smuzhiyun u16 hdr_len;
28*4882a593Smuzhiyun u8 rci2_sig[4];
29*4882a593Smuzhiyun u16 resvd1;
30*4882a593Smuzhiyun u32 resvd2;
31*4882a593Smuzhiyun u32 resvd3;
32*4882a593Smuzhiyun u8 major_rev;
33*4882a593Smuzhiyun u8 minor_rev;
34*4882a593Smuzhiyun u16 num_of_structs;
35*4882a593Smuzhiyun u32 rci2_len;
36*4882a593Smuzhiyun u16 rci2_chksum;
37*4882a593Smuzhiyun } __packed;
38*4882a593Smuzhiyun
39*4882a593Smuzhiyun static u8 *rci2_base;
40*4882a593Smuzhiyun static u32 rci2_table_len;
41*4882a593Smuzhiyun unsigned long rci2_table_phys __ro_after_init = EFI_INVALID_TABLE_ADDR;
42*4882a593Smuzhiyun
raw_table_read(struct file * file,struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t pos,size_t count)43*4882a593Smuzhiyun static ssize_t raw_table_read(struct file *file, struct kobject *kobj,
44*4882a593Smuzhiyun struct bin_attribute *attr, char *buf,
45*4882a593Smuzhiyun loff_t pos, size_t count)
46*4882a593Smuzhiyun {
47*4882a593Smuzhiyun memcpy(buf, attr->private + pos, count);
48*4882a593Smuzhiyun return count;
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun static BIN_ATTR(rci2, S_IRUSR, raw_table_read, NULL, 0);
52*4882a593Smuzhiyun
checksum(void)53*4882a593Smuzhiyun static u16 checksum(void)
54*4882a593Smuzhiyun {
55*4882a593Smuzhiyun u8 len_is_odd = rci2_table_len % 2;
56*4882a593Smuzhiyun u32 chksum_len = rci2_table_len;
57*4882a593Smuzhiyun u16 *base = (u16 *)rci2_base;
58*4882a593Smuzhiyun u8 buf[2] = {0};
59*4882a593Smuzhiyun u32 offset = 0;
60*4882a593Smuzhiyun u16 chksum = 0;
61*4882a593Smuzhiyun
62*4882a593Smuzhiyun if (len_is_odd)
63*4882a593Smuzhiyun chksum_len -= 1;
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun while (offset < chksum_len) {
66*4882a593Smuzhiyun chksum += *base;
67*4882a593Smuzhiyun offset += 2;
68*4882a593Smuzhiyun base++;
69*4882a593Smuzhiyun }
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun if (len_is_odd) {
72*4882a593Smuzhiyun buf[0] = *(u8 *)base;
73*4882a593Smuzhiyun chksum += *(u16 *)(buf);
74*4882a593Smuzhiyun }
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun return chksum;
77*4882a593Smuzhiyun }
78*4882a593Smuzhiyun
efi_rci2_sysfs_init(void)79*4882a593Smuzhiyun static int __init efi_rci2_sysfs_init(void)
80*4882a593Smuzhiyun {
81*4882a593Smuzhiyun struct kobject *tables_kobj;
82*4882a593Smuzhiyun int ret = -ENOMEM;
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun if (rci2_table_phys == EFI_INVALID_TABLE_ADDR)
85*4882a593Smuzhiyun return 0;
86*4882a593Smuzhiyun
87*4882a593Smuzhiyun rci2_base = memremap(rci2_table_phys,
88*4882a593Smuzhiyun sizeof(struct rci2_table_global_hdr),
89*4882a593Smuzhiyun MEMREMAP_WB);
90*4882a593Smuzhiyun if (!rci2_base) {
91*4882a593Smuzhiyun pr_debug("RCI2 table init failed - could not map RCI2 table\n");
92*4882a593Smuzhiyun goto err;
93*4882a593Smuzhiyun }
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun if (strncmp(rci2_base +
96*4882a593Smuzhiyun offsetof(struct rci2_table_global_hdr, rci2_sig),
97*4882a593Smuzhiyun RCI_SIGNATURE, 4)) {
98*4882a593Smuzhiyun pr_debug("RCI2 table init failed - incorrect signature\n");
99*4882a593Smuzhiyun ret = -ENODEV;
100*4882a593Smuzhiyun goto err_unmap;
101*4882a593Smuzhiyun }
102*4882a593Smuzhiyun
103*4882a593Smuzhiyun rci2_table_len = *(u32 *)(rci2_base +
104*4882a593Smuzhiyun offsetof(struct rci2_table_global_hdr,
105*4882a593Smuzhiyun rci2_len));
106*4882a593Smuzhiyun
107*4882a593Smuzhiyun memunmap(rci2_base);
108*4882a593Smuzhiyun
109*4882a593Smuzhiyun if (!rci2_table_len) {
110*4882a593Smuzhiyun pr_debug("RCI2 table init failed - incorrect table length\n");
111*4882a593Smuzhiyun goto err;
112*4882a593Smuzhiyun }
113*4882a593Smuzhiyun
114*4882a593Smuzhiyun rci2_base = memremap(rci2_table_phys, rci2_table_len, MEMREMAP_WB);
115*4882a593Smuzhiyun if (!rci2_base) {
116*4882a593Smuzhiyun pr_debug("RCI2 table - could not map RCI2 table\n");
117*4882a593Smuzhiyun goto err;
118*4882a593Smuzhiyun }
119*4882a593Smuzhiyun
120*4882a593Smuzhiyun if (checksum() != 0) {
121*4882a593Smuzhiyun pr_debug("RCI2 table - incorrect checksum\n");
122*4882a593Smuzhiyun ret = -ENODEV;
123*4882a593Smuzhiyun goto err_unmap;
124*4882a593Smuzhiyun }
125*4882a593Smuzhiyun
126*4882a593Smuzhiyun tables_kobj = kobject_create_and_add("tables", efi_kobj);
127*4882a593Smuzhiyun if (!tables_kobj) {
128*4882a593Smuzhiyun pr_debug("RCI2 table - tables_kobj creation failed\n");
129*4882a593Smuzhiyun goto err_unmap;
130*4882a593Smuzhiyun }
131*4882a593Smuzhiyun
132*4882a593Smuzhiyun bin_attr_rci2.size = rci2_table_len;
133*4882a593Smuzhiyun bin_attr_rci2.private = rci2_base;
134*4882a593Smuzhiyun ret = sysfs_create_bin_file(tables_kobj, &bin_attr_rci2);
135*4882a593Smuzhiyun if (ret != 0) {
136*4882a593Smuzhiyun pr_debug("RCI2 table - rci2 sysfs bin file creation failed\n");
137*4882a593Smuzhiyun kobject_del(tables_kobj);
138*4882a593Smuzhiyun kobject_put(tables_kobj);
139*4882a593Smuzhiyun goto err_unmap;
140*4882a593Smuzhiyun }
141*4882a593Smuzhiyun
142*4882a593Smuzhiyun return 0;
143*4882a593Smuzhiyun
144*4882a593Smuzhiyun err_unmap:
145*4882a593Smuzhiyun memunmap(rci2_base);
146*4882a593Smuzhiyun err:
147*4882a593Smuzhiyun pr_debug("RCI2 table - sysfs initialization failed\n");
148*4882a593Smuzhiyun return ret;
149*4882a593Smuzhiyun }
150*4882a593Smuzhiyun late_initcall(efi_rci2_sysfs_init);
151