1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Address translation interface via ACPI DSM.
4 * Copyright (C) 2018 Intel Corporation
5 *
6 * Specification for this interface is available at:
7 *
8 * https://cdrdv2.intel.com/v1/dl/getContent/603354
9 */
10
11#include <linux/acpi.h>
12#include <linux/adxl.h>
13
14#define ADXL_REVISION 0x1
15#define ADXL_IDX_GET_ADDR_PARAMS 0x1
16#define ADXL_IDX_FORWARD_TRANSLATE 0x2
17#define ACPI_ADXL_PATH "\\_SB.ADXL"
18
19/*
20 * The specification doesn't provide a limit on how many
21 * components are in a memory address. But since we allocate
22 * memory based on the number the BIOS tells us, we should
23 * defend against insane values.
24 */
25#define ADXL_MAX_COMPONENTS 500
26
27#undef pr_fmt
28#define pr_fmt(fmt) "ADXL: " fmt
29
30static acpi_handle handle;
31static union acpi_object *params;
32static const guid_t adxl_guid =
33 GUID_INIT(0xAA3C050A, 0x7EA4, 0x4C1F,
34 0xAF, 0xDA, 0x12, 0x67, 0xDF, 0xD3, 0xD4, 0x8D);
35
36static int adxl_count;
37static char **adxl_component_names;
38
39static union acpi_object *adxl_dsm(int cmd, union acpi_object argv[])
40{
41 union acpi_object *obj, *o;
42
43 obj = acpi_evaluate_dsm_typed(handle, &adxl_guid, ADXL_REVISION,
44 cmd, argv, ACPI_TYPE_PACKAGE);
45 if (!obj) {
46 pr_info("DSM call failed for cmd=%d\n", cmd);
47 return NULL;
48 }
49
50 if (obj->package.count != 2) {
51 pr_info("Bad pkg count %d\n", obj->package.count);
52 goto err;
53 }
54
55 o = obj->package.elements;
56 if (o->type != ACPI_TYPE_INTEGER) {
57 pr_info("Bad 1st element type %d\n", o->type);
58 goto err;
59 }
60 if (o->integer.value) {
61 pr_info("Bad ret val %llu\n", o->integer.value);
62 goto err;
63 }
64
65 o = obj->package.elements + 1;
66 if (o->type != ACPI_TYPE_PACKAGE) {
67 pr_info("Bad 2nd element type %d\n", o->type);
68 goto err;
69 }
70 return obj;
71
72err:
73 ACPI_FREE(obj);
74 return NULL;
75}
76
77/**
78 * adxl_get_component_names - get list of memory component names
79 * Returns NULL terminated list of string names
80 *
81 * Give the caller a pointer to the list of memory component names
82 * e.g. { "SystemAddress", "ProcessorSocketId", "ChannelId", ... NULL }
83 * Caller should count how many strings in order to allocate a buffer
84 * for the return from adxl_decode().
85 */
86const char * const *adxl_get_component_names(void)
87{
88 return (const char * const *)adxl_component_names;
89}
90EXPORT_SYMBOL_GPL(adxl_get_component_names);
91
92/**
93 * adxl_decode - ask BIOS to decode a system address to memory address
94 * @addr: the address to decode
95 * @component_values: pointer to array of values for each component
96 * Returns 0 on success, negative error code otherwise
97 *
98 * The index of each value returned in the array matches the index of
99 * each component name returned by adxl_get_component_names().
100 * Components that are not defined for this address translation (e.g.
101 * mirror channel number for a non-mirrored address) are set to ~0ull.
102 */
103int adxl_decode(u64 addr, u64 component_values[])
104{
105 union acpi_object argv4[2], *results, *r;
106 int i, cnt;
107
108 if (!adxl_component_names)
109 return -EOPNOTSUPP;
110
111 argv4[0].type = ACPI_TYPE_PACKAGE;
112 argv4[0].package.count = 1;
113 argv4[0].package.elements = &argv4[1];
114 argv4[1].integer.type = ACPI_TYPE_INTEGER;
115 argv4[1].integer.value = addr;
116
117 results = adxl_dsm(ADXL_IDX_FORWARD_TRANSLATE, argv4);
118 if (!results)
119 return -EINVAL;
120
121 r = results->package.elements + 1;
122 cnt = r->package.count;
123 if (cnt != adxl_count) {
124 ACPI_FREE(results);
125 return -EINVAL;
126 }
127 r = r->package.elements;
128
129 for (i = 0; i < cnt; i++)
130 component_values[i] = r[i].integer.value;
131
132 ACPI_FREE(results);
133
134 return 0;
135}
136EXPORT_SYMBOL_GPL(adxl_decode);
137
138static int __init adxl_init(void)
139{
140 char *path = ACPI_ADXL_PATH;
141 union acpi_object *p;
142 acpi_status status;
143 int i;
144
145 status = acpi_get_handle(NULL, path, &handle);
146 if (ACPI_FAILURE(status)) {
147 pr_debug("No ACPI handle for path %s\n", path);
148 return -ENODEV;
149 }
150
151 if (!acpi_has_method(handle, "_DSM")) {
152 pr_info("No DSM method\n");
153 return -ENODEV;
154 }
155
156 if (!acpi_check_dsm(handle, &adxl_guid, ADXL_REVISION,
157 ADXL_IDX_GET_ADDR_PARAMS |
158 ADXL_IDX_FORWARD_TRANSLATE)) {
159 pr_info("DSM method does not support forward translate\n");
160 return -ENODEV;
161 }
162
163 params = adxl_dsm(ADXL_IDX_GET_ADDR_PARAMS, NULL);
164 if (!params) {
165 pr_info("Failed to get component names\n");
166 return -ENODEV;
167 }
168
169 p = params->package.elements + 1;
170 adxl_count = p->package.count;
171 if (adxl_count > ADXL_MAX_COMPONENTS) {
172 pr_info("Insane number of address component names %d\n", adxl_count);
173 ACPI_FREE(params);
174 return -ENODEV;
175 }
176 p = p->package.elements;
177
178 /*
179 * Allocate one extra for NULL termination.
180 */
181 adxl_component_names = kcalloc(adxl_count + 1, sizeof(char *), GFP_KERNEL);
182 if (!adxl_component_names) {
183 ACPI_FREE(params);
184 return -ENOMEM;
185 }
186
187 for (i = 0; i < adxl_count; i++)
188 adxl_component_names[i] = p[i].string.pointer;
189
190 return 0;
191}
192subsys_initcall(adxl_init);
193