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);