drivers/acpi/acpi_adxl.c

   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
  30 static acpi_handle handle;
  31 static union acpi_object *params;
  32 static const guid_t adxl_guid =
  33         GUID_INIT(0xAA3C050A, 0x7EA4, 0x4C1F,
  34                   0xAF, 0xDA, 0x12, 0x67, 0xDF, 0xD3, 0xD4, 0x8D);
  35
  36 static int adxl_count;
  37 static char **adxl_component_names;
  38
  39 static 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
  72 err:
  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  */
  86 const char * const *adxl_get_component_names(void)
  87 {
  88         return (const char * const *)adxl_component_names;
  89 }
  90 EXPORT_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  */
 103 int 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 }
 136 EXPORT_SYMBOL_GPL(adxl_decode);
 137
 138 static 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 }
 192 subsys_initcall(adxl_init);