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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * ChromeOS specific ACPI extensions4 *5 * Copyright 2022 Google LLC6 *7 * This driver attaches to the ChromeOS ACPI device and then exports the8 * values reported by the ACPI in a sysfs directory. All values are9 * presented in the string form (numbers as decimal values) and can be10 * accessed as the contents of the appropriate read only files in the11 * 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 420 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 67static unsigned int chromeos_acpi_gpio_groups;68 69/* Parse the ACPI package and return the data related to that attribute */70static 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;118truncating: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 129static 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 150static 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 160static 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 172static 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 195DEV_ATTR(binf2, BINF.2)196DEV_ATTR(binf3, BINF.3)197DEV_ATTR(chsw, CHSW)198DEV_ATTR(fmap, FMAP)199DEV_ATTR(frid, FRID)200DEV_ATTR(fwid, FWID)201DEV_ATTR(hwid, HWID)202DEV_ATTR(meck, MECK)203DEV_ATTR(vbnv0, VBNV.0)204DEV_ATTR(vbnv1, VBNV.1)205DEV_ATTR(vdat, VDAT)206 207static 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 NULL220};221 222static 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 show229 * the present number of groups only, others are hidden.230 */231GPIO_ATTR_GROUP(gpio0, "GPIO.0", 0)232GPIO_ATTR_GROUP(gpio1, "GPIO.1", 1)233GPIO_ATTR_GROUP(gpio2, "GPIO.2", 2)234GPIO_ATTR_GROUP(gpio3, "GPIO.3", 3)235GPIO_ATTR_GROUP(gpio4, "GPIO.4", 4)236GPIO_ATTR_GROUP(gpio5, "GPIO.5", 5)237GPIO_ATTR_GROUP(gpio6, "GPIO.6", 6)238GPIO_ATTR_GROUP(gpio7, "GPIO.7", 7)239 240static 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 NULL251};252 253static 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 of259 * 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 267static const struct acpi_device_id chromeos_device_ids[] = {268 { "GGL0001", 0 },269 { "GOOG0016", 0 },270 {}271};272MODULE_DEVICE_TABLE(acpi, chromeos_device_ids);273 274static 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};282module_platform_driver(chromeos_acpi_device_driver);283 284MODULE_AUTHOR("Muhammad Usama Anjum <usama.anjum@collabora.com>");285MODULE_LICENSE("GPL");286MODULE_DESCRIPTION("ChromeOS specific ACPI extensions");287