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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");