drivers/platform/chrome/chromeos_acpi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * ChromeOS specific ACPI extensions
   4  *
   5  * Copyright 2022 Google LLC
   6  *
   7  * This driver attaches to the ChromeOS ACPI device and then exports the
   8  * values reported by the ACPI in a sysfs directory. All values are
   9  * presented in the string form (numbers as decimal values) and can be
  10  * accessed as the contents of the appropriate read only files in the
  11  * sysfs directory tree.
  12  */
  13 #include <linux/acpi.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/kernel.h>
  16 #include <linux/list.h>
  17 #include <linux/module.h>
  18
  19 #define ACPI_ATTR_NAME_LEN 4
  20
  21 #define DEV_ATTR(_var, _name)                                   \
  22         static struct device_attribute dev_attr_##_var =        \
  23                 __ATTR(_name, 0444, chromeos_first_level_attr_show, NULL);
  24
  25 #define GPIO_ATTR_GROUP(_group, _name, _num)                                            \
  26         static umode_t attr_is_visible_gpio_##_num(struct kobject *kobj,                \
  27                                                    struct attribute *attr, int n)       \
  28         {                                                                               \
  29                 if (_num < chromeos_acpi_gpio_groups)                                   \
  30                         return attr->mode;                                              \
  31                 return 0;                                                               \
  32         }                                                                               \
  33         static ssize_t chromeos_attr_show_gpio_##_num(struct device *dev,               \
  34                                                       struct device_attribute *attr,    \
  35                                                       char *buf)                        \
  36         {                                                                               \
  37                 char name[ACPI_ATTR_NAME_LEN + 1];                                      \
  38                 int ret, num;                                                           \
  39                                                                                         \
  40                 ret = parse_attr_name(attr->attr.name, name, &num);                     \
  41                 if (ret)                                                                \
  42                         return ret;                                                     \
  43                 return chromeos_acpi_evaluate_method(dev, _num, num, name, buf);        \
  44         }                                                                               \
  45         static struct device_attribute dev_attr_0_##_group =                            \
  46                 __ATTR(GPIO.0, 0444, chromeos_attr_show_gpio_##_num, NULL);             \
  47         static struct device_attribute dev_attr_1_##_group =                            \
  48                 __ATTR(GPIO.1, 0444, chromeos_attr_show_gpio_##_num, NULL);             \
  49         static struct device_attribute dev_attr_2_##_group =                            \
  50                 __ATTR(GPIO.2, 0444, chromeos_attr_show_gpio_##_num, NULL);             \
  51         static struct device_attribute dev_attr_3_##_group =                            \
  52                 __ATTR(GPIO.3, 0444, chromeos_attr_show_gpio_##_num, NULL);             \
  53                                                                                         \
  54         static struct attribute *attrs_##_group[] = {                                   \
  55                 &dev_attr_0_##_group.attr,                                              \
  56                 &dev_attr_1_##_group.attr,                                              \
  57                 &dev_attr_2_##_group.attr,                                              \
  58                 &dev_attr_3_##_group.attr,                                              \
  59                 NULL                                                                    \
  60         };                                                                              \
  61         static const struct attribute_group attr_group_##_group = {                     \
  62                 .name = _name,                                                          \
  63                 .is_visible = attr_is_visible_gpio_##_num,                              \
  64                 .attrs = attrs_##_group,                                                \
  65         };
  66
  67 static unsigned int chromeos_acpi_gpio_groups;
  68
  69 /* Parse the ACPI package and return the data related to that attribute */
  70 static int chromeos_acpi_handle_package(struct device *dev, union acpi_object *obj,
  71                                         int pkg_num, int sub_pkg_num, char *name, char *buf)
  72 {
  73         union acpi_object *element = obj->package.elements;
  74
  75         if (pkg_num >= obj->package.count)
  76                 return -EINVAL;
  77         element += pkg_num;
  78
  79         if (element->type == ACPI_TYPE_PACKAGE) {
  80                 if (sub_pkg_num >= element->package.count)
  81                         return -EINVAL;
  82                 /* select sub element inside this package */
  83                 element = element->package.elements;
  84                 element += sub_pkg_num;
  85         }
  86
  87         switch (element->type) {
  88         case ACPI_TYPE_INTEGER:
  89                 return sysfs_emit(buf, "%d\n", (int)element->integer.value);
  90         case ACPI_TYPE_STRING:
  91                 return sysfs_emit(buf, "%s\n", element->string.pointer);
  92         case ACPI_TYPE_BUFFER:
  93                 {
  94                         int i, r, at, room_left;
  95                         const int byte_per_line = 16;
  96
  97                         at = 0;
  98                         room_left = PAGE_SIZE - 1;
  99                         for (i = 0; i < element->buffer.length && room_left; i += byte_per_line) {
 100                                 r = hex_dump_to_buffer(element->buffer.pointer + i,
 101                                                        element->buffer.length - i,
 102                                                        byte_per_line, 1, buf + at, room_left,
 103                                                        false);
 104                                 if (r > room_left)
 105                                         goto truncating;
 106                                 at += r;
 107                                 room_left -= r;
 108
 109                                 r = sysfs_emit_at(buf, at, "\n");
 110                                 if (!r)
 111                                         goto truncating;
 112                                 at += r;
 113                                 room_left -= r;
 114                         }
 115
 116                         buf[at] = 0;
 117                         return at;
 118 truncating:
 119                         dev_info_once(dev, "truncating sysfs content for %s\n", name);
 120                         sysfs_emit_at(buf, PAGE_SIZE - 4, "..\n");
 121                         return PAGE_SIZE - 1;
 122                 }
 123         default:
 124                 dev_err(dev, "element type %d not supported\n", element->type);
 125                 return -EINVAL;
 126         }
 127 }
 128
 129 static int chromeos_acpi_evaluate_method(struct device *dev, int pkg_num, int sub_pkg_num,
 130                                          char *name, char *buf)
 131 {
 132         struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 133         acpi_status status;
 134         int ret = -EINVAL;
 135
 136         status = acpi_evaluate_object(ACPI_HANDLE(dev), name, NULL, &output);
 137         if (ACPI_FAILURE(status)) {
 138                 dev_err(dev, "failed to retrieve %s. %s\n", name, acpi_format_exception(status));
 139                 return ret;
 140         }
 141
 142         if (((union acpi_object *)output.pointer)->type == ACPI_TYPE_PACKAGE)
 143                 ret = chromeos_acpi_handle_package(dev, output.pointer, pkg_num, sub_pkg_num,
 144                                                    name, buf);
 145
 146         kfree(output.pointer);
 147         return ret;
 148 }
 149
 150 static int parse_attr_name(const char *name, char *attr_name, int *attr_num)
 151 {
 152         int ret;
 153
 154         ret = strscpy(attr_name, name, ACPI_ATTR_NAME_LEN + 1);
 155         if (ret == -E2BIG)
 156                 return kstrtoint(&name[ACPI_ATTR_NAME_LEN + 1], 0, attr_num);
 157         return 0;
 158 }
 159
 160 static ssize_t chromeos_first_level_attr_show(struct device *dev, struct device_attribute *attr,
 161                                               char *buf)
 162 {
 163         char attr_name[ACPI_ATTR_NAME_LEN + 1];
 164         int ret, attr_num = 0;
 165
 166         ret = parse_attr_name(attr->attr.name, attr_name, &attr_num);
 167         if (ret)
 168                 return ret;
 169         return chromeos_acpi_evaluate_method(dev, attr_num, 0, attr_name, buf);
 170 }
 171
 172 static unsigned int get_gpio_pkg_num(struct device *dev)
 173 {
 174         struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 175         union acpi_object *obj;
 176         acpi_status status;
 177         unsigned int count = 0;
 178         char *name = "GPIO";
 179
 180         status = acpi_evaluate_object(ACPI_HANDLE(dev), name, NULL, &output);
 181         if (ACPI_FAILURE(status)) {
 182                 dev_err(dev, "failed to retrieve %s. %s\n", name, acpi_format_exception(status));
 183                 return count;
 184         }
 185
 186         obj = output.pointer;
 187
 188         if (obj->type == ACPI_TYPE_PACKAGE)
 189                 count = obj->package.count;
 190
 191         kfree(output.pointer);
 192         return count;
 193 }
 194
 195 DEV_ATTR(binf2, BINF.2)
 196 DEV_ATTR(binf3, BINF.3)
 197 DEV_ATTR(chsw, CHSW)
 198 DEV_ATTR(fmap, FMAP)
 199 DEV_ATTR(frid, FRID)
 200 DEV_ATTR(fwid, FWID)
 201 DEV_ATTR(hwid, HWID)
 202 DEV_ATTR(meck, MECK)
 203 DEV_ATTR(vbnv0, VBNV.0)
 204 DEV_ATTR(vbnv1, VBNV.1)
 205 DEV_ATTR(vdat, VDAT)
 206
 207 static struct attribute *first_level_attrs[] = {
 208         &dev_attr_binf2.attr,
 209         &dev_attr_binf3.attr,
 210         &dev_attr_chsw.attr,
 211         &dev_attr_fmap.attr,
 212         &dev_attr_frid.attr,
 213         &dev_attr_fwid.attr,
 214         &dev_attr_hwid.attr,
 215         &dev_attr_meck.attr,
 216         &dev_attr_vbnv0.attr,
 217         &dev_attr_vbnv1.attr,
 218         &dev_attr_vdat.attr,
 219         NULL
 220 };
 221
 222 static const struct attribute_group first_level_attr_group = {
 223         .attrs = first_level_attrs,
 224 };
 225
 226 /*
 227  * Every platform can have a different number of GPIO attribute groups.
 228  * Define upper limit groups. At run time, the platform decides to show
 229  * the present number of groups only, others are hidden.
 230  */
 231 GPIO_ATTR_GROUP(gpio0, "GPIO.0", 0)
 232 GPIO_ATTR_GROUP(gpio1, "GPIO.1", 1)
 233 GPIO_ATTR_GROUP(gpio2, "GPIO.2", 2)
 234 GPIO_ATTR_GROUP(gpio3, "GPIO.3", 3)
 235 GPIO_ATTR_GROUP(gpio4, "GPIO.4", 4)
 236 GPIO_ATTR_GROUP(gpio5, "GPIO.5", 5)
 237 GPIO_ATTR_GROUP(gpio6, "GPIO.6", 6)
 238 GPIO_ATTR_GROUP(gpio7, "GPIO.7", 7)
 239
 240 static const struct attribute_group *chromeos_acpi_all_groups[] = {
 241         &first_level_attr_group,
 242         &attr_group_gpio0,
 243         &attr_group_gpio1,
 244         &attr_group_gpio2,
 245         &attr_group_gpio3,
 246         &attr_group_gpio4,
 247         &attr_group_gpio5,
 248         &attr_group_gpio6,
 249         &attr_group_gpio7,
 250         NULL
 251 };
 252
 253 static int chromeos_acpi_device_probe(struct platform_device *pdev)
 254 {
 255         chromeos_acpi_gpio_groups = get_gpio_pkg_num(&pdev->dev);
 256
 257         /*
 258          * If the platform has more GPIO attribute groups than the number of
 259          * groups this driver supports, give out a warning message.
 260          */
 261         if (chromeos_acpi_gpio_groups > ARRAY_SIZE(chromeos_acpi_all_groups) - 2)
 262                 dev_warn(&pdev->dev, "Only %zu GPIO attr groups supported by the driver out of total %u.\n",
 263                          ARRAY_SIZE(chromeos_acpi_all_groups) - 2, chromeos_acpi_gpio_groups);
 264         return 0;
 265 }
 266
 267 static const struct acpi_device_id chromeos_device_ids[] = {
 268         { "GGL0001", 0 },
 269         { "GOOG0016", 0 },
 270         {}
 271 };
 272 MODULE_DEVICE_TABLE(acpi, chromeos_device_ids);
 273
 274 static struct platform_driver chromeos_acpi_device_driver = {
 275         .probe = chromeos_acpi_device_probe,
 276         .driver = {
 277                 .name = KBUILD_MODNAME,
 278                 .dev_groups = chromeos_acpi_all_groups,
 279                 .acpi_match_table = chromeos_device_ids,
 280         }
 281 };
 282 module_platform_driver(chromeos_acpi_device_driver);
 283
 284 MODULE_AUTHOR("Muhammad Usama Anjum <[email protected]>");
 285 MODULE_LICENSE("GPL");
 286 MODULE_DESCRIPTION("ChromeOS specific ACPI extensions");