chromeos_acpi.c (7736B)
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 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 return sysfs_emit(buf, "%s\n", element->buffer.pointer); 94 default: 95 dev_err(dev, "element type %d not supported\n", element->type); 96 return -EINVAL; 97 } 98} 99 100static int chromeos_acpi_evaluate_method(struct device *dev, int pkg_num, int sub_pkg_num, 101 char *name, char *buf) 102{ 103 struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL }; 104 acpi_status status; 105 int ret = -EINVAL; 106 107 status = acpi_evaluate_object(ACPI_HANDLE(dev), name, NULL, &output); 108 if (ACPI_FAILURE(status)) { 109 dev_err(dev, "failed to retrieve %s. %s\n", name, acpi_format_exception(status)); 110 return ret; 111 } 112 113 if (((union acpi_object *)output.pointer)->type == ACPI_TYPE_PACKAGE) 114 ret = chromeos_acpi_handle_package(dev, output.pointer, pkg_num, sub_pkg_num, 115 name, buf); 116 117 kfree(output.pointer); 118 return ret; 119} 120 121static int parse_attr_name(const char *name, char *attr_name, int *attr_num) 122{ 123 int ret; 124 125 ret = strscpy(attr_name, name, ACPI_ATTR_NAME_LEN + 1); 126 if (ret == -E2BIG) 127 return kstrtoint(&name[ACPI_ATTR_NAME_LEN + 1], 0, attr_num); 128 return 0; 129} 130 131static ssize_t chromeos_first_level_attr_show(struct device *dev, struct device_attribute *attr, 132 char *buf) 133{ 134 char attr_name[ACPI_ATTR_NAME_LEN + 1]; 135 int ret, attr_num = 0; 136 137 ret = parse_attr_name(attr->attr.name, attr_name, &attr_num); 138 if (ret) 139 return ret; 140 return chromeos_acpi_evaluate_method(dev, attr_num, 0, attr_name, buf); 141} 142 143static unsigned int get_gpio_pkg_num(struct device *dev) 144{ 145 struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL }; 146 union acpi_object *obj; 147 acpi_status status; 148 unsigned int count = 0; 149 char *name = "GPIO"; 150 151 status = acpi_evaluate_object(ACPI_HANDLE(dev), name, NULL, &output); 152 if (ACPI_FAILURE(status)) { 153 dev_err(dev, "failed to retrieve %s. %s\n", name, acpi_format_exception(status)); 154 return count; 155 } 156 157 obj = output.pointer; 158 159 if (obj->type == ACPI_TYPE_PACKAGE) 160 count = obj->package.count; 161 162 kfree(output.pointer); 163 return count; 164} 165 166DEV_ATTR(binf2, BINF.2) 167DEV_ATTR(binf3, BINF.3) 168DEV_ATTR(chsw, CHSW) 169DEV_ATTR(fmap, FMAP) 170DEV_ATTR(frid, FRID) 171DEV_ATTR(fwid, FWID) 172DEV_ATTR(hwid, HWID) 173DEV_ATTR(meck, MECK) 174DEV_ATTR(vbnv0, VBNV.0) 175DEV_ATTR(vbnv1, VBNV.1) 176DEV_ATTR(vdat, VDAT) 177 178static struct attribute *first_level_attrs[] = { 179 &dev_attr_binf2.attr, 180 &dev_attr_binf3.attr, 181 &dev_attr_chsw.attr, 182 &dev_attr_fmap.attr, 183 &dev_attr_frid.attr, 184 &dev_attr_fwid.attr, 185 &dev_attr_hwid.attr, 186 &dev_attr_meck.attr, 187 &dev_attr_vbnv0.attr, 188 &dev_attr_vbnv1.attr, 189 &dev_attr_vdat.attr, 190 NULL 191}; 192 193static const struct attribute_group first_level_attr_group = { 194 .attrs = first_level_attrs, 195}; 196 197/* 198 * Every platform can have a different number of GPIO attribute groups. 199 * Define upper limit groups. At run time, the platform decides to show 200 * the present number of groups only, others are hidden. 201 */ 202GPIO_ATTR_GROUP(gpio0, "GPIO.0", 0) 203GPIO_ATTR_GROUP(gpio1, "GPIO.1", 1) 204GPIO_ATTR_GROUP(gpio2, "GPIO.2", 2) 205GPIO_ATTR_GROUP(gpio3, "GPIO.3", 3) 206GPIO_ATTR_GROUP(gpio4, "GPIO.4", 4) 207GPIO_ATTR_GROUP(gpio5, "GPIO.5", 5) 208GPIO_ATTR_GROUP(gpio6, "GPIO.6", 6) 209GPIO_ATTR_GROUP(gpio7, "GPIO.7", 7) 210 211static const struct attribute_group *chromeos_acpi_all_groups[] = { 212 &first_level_attr_group, 213 &attr_group_gpio0, 214 &attr_group_gpio1, 215 &attr_group_gpio2, 216 &attr_group_gpio3, 217 &attr_group_gpio4, 218 &attr_group_gpio5, 219 &attr_group_gpio6, 220 &attr_group_gpio7, 221 NULL 222}; 223 224static int chromeos_acpi_device_probe(struct platform_device *pdev) 225{ 226 chromeos_acpi_gpio_groups = get_gpio_pkg_num(&pdev->dev); 227 228 /* 229 * If the platform has more GPIO attribute groups than the number of 230 * groups this driver supports, give out a warning message. 231 */ 232 if (chromeos_acpi_gpio_groups > ARRAY_SIZE(chromeos_acpi_all_groups) - 2) 233 dev_warn(&pdev->dev, "Only %zu GPIO attr groups supported by the driver out of total %u.\n", 234 ARRAY_SIZE(chromeos_acpi_all_groups) - 2, chromeos_acpi_gpio_groups); 235 return 0; 236} 237 238/* GGL is valid PNP ID of Google. PNP ID can be used with the ACPI devices. */ 239static const struct acpi_device_id chromeos_device_ids[] = { 240 { "GGL0001", 0 }, 241 {} 242}; 243MODULE_DEVICE_TABLE(acpi, chromeos_device_ids); 244 245static struct platform_driver chromeos_acpi_device_driver = { 246 .probe = chromeos_acpi_device_probe, 247 .driver = { 248 .name = KBUILD_MODNAME, 249 .dev_groups = chromeos_acpi_all_groups, 250 .acpi_match_table = chromeos_device_ids, 251 } 252}; 253module_platform_driver(chromeos_acpi_device_driver); 254 255MODULE_AUTHOR("Muhammad Usama Anjum <usama.anjum@collabora.com>"); 256MODULE_LICENSE("GPL"); 257MODULE_DESCRIPTION("ChromeOS specific ACPI extensions");