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// SPDX-License-Identifier: GPL-2.0-only
/*
* ChromeOS specific ACPI extensions
*
* Copyright 2022 Google LLC
*
* This driver attaches to the ChromeOS ACPI device and then exports the
* values reported by the ACPI in a sysfs directory. All values are
* presented in the string form (numbers as decimal values) and can be
* accessed as the contents of the appropriate read only files in the
* sysfs directory tree.
*/
#include <linux/acpi.h>
#include <linux/platform_device.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#define ACPI_ATTR_NAME_LEN 4
#define DEV_ATTR(_var, _name) \
static struct device_attribute dev_attr_##_var = \
__ATTR(_name, 0444, chromeos_first_level_attr_show, NULL);
#define GPIO_ATTR_GROUP(_group, _name, _num) \
static umode_t attr_is_visible_gpio_##_num(struct kobject *kobj, \
struct attribute *attr, int n) \
{ \
if (_num < chromeos_acpi_gpio_groups) \
return attr->mode; \
return 0; \
} \
static ssize_t chromeos_attr_show_gpio_##_num(struct device *dev, \
struct device_attribute *attr, \
char *buf) \
{ \
char name[ACPI_ATTR_NAME_LEN + 1]; \
int ret, num; \
\
ret = parse_attr_name(attr->attr.name, name, &num); \
if (ret) \
return ret; \
return chromeos_acpi_evaluate_method(dev, _num, num, name, buf); \
} \
static struct device_attribute dev_attr_0_##_group = \
__ATTR(GPIO.0, 0444, chromeos_attr_show_gpio_##_num, NULL); \
static struct device_attribute dev_attr_1_##_group = \
__ATTR(GPIO.1, 0444, chromeos_attr_show_gpio_##_num, NULL); \
static struct device_attribute dev_attr_2_##_group = \
__ATTR(GPIO.2, 0444, chromeos_attr_show_gpio_##_num, NULL); \
static struct device_attribute dev_attr_3_##_group = \
__ATTR(GPIO.3, 0444, chromeos_attr_show_gpio_##_num, NULL); \
\
static struct attribute *attrs_##_group[] = { \
&dev_attr_0_##_group.attr, \
&dev_attr_1_##_group.attr, \
&dev_attr_2_##_group.attr, \
&dev_attr_3_##_group.attr, \
NULL \
}; \
static const struct attribute_group attr_group_##_group = { \
.name = _name, \
.is_visible = attr_is_visible_gpio_##_num, \
.attrs = attrs_##_group, \
};
static unsigned int chromeos_acpi_gpio_groups;
/* Parse the ACPI package and return the data related to that attribute */
static int chromeos_acpi_handle_package(struct device *dev, union acpi_object *obj,
int pkg_num, int sub_pkg_num, char *name, char *buf)
{
union acpi_object *element = obj->package.elements;
if (pkg_num >= obj->package.count)
return -EINVAL;
element += pkg_num;
if (element->type == ACPI_TYPE_PACKAGE) {
if (sub_pkg_num >= element->package.count)
return -EINVAL;
/* select sub element inside this package */
element = element->package.elements;
element += sub_pkg_num;
}
switch (element->type) {
case ACPI_TYPE_INTEGER:
return sysfs_emit(buf, "%d\n", (int)element->integer.value);
case ACPI_TYPE_STRING:
return sysfs_emit(buf, "%s\n", element->string.pointer);
case ACPI_TYPE_BUFFER:
return sysfs_emit(buf, "%s\n", element->buffer.pointer);
default:
dev_err(dev, "element type %d not supported\n", element->type);
return -EINVAL;
}
}
static int chromeos_acpi_evaluate_method(struct device *dev, int pkg_num, int sub_pkg_num,
char *name, char *buf)
{
struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
acpi_status status;
int ret = -EINVAL;
status = acpi_evaluate_object(ACPI_HANDLE(dev), name, NULL, &output);
if (ACPI_FAILURE(status)) {
dev_err(dev, "failed to retrieve %s. %s\n", name, acpi_format_exception(status));
return ret;
}
if (((union acpi_object *)output.pointer)->type == ACPI_TYPE_PACKAGE)
ret = chromeos_acpi_handle_package(dev, output.pointer, pkg_num, sub_pkg_num,
name, buf);
kfree(output.pointer);
return ret;
}
static int parse_attr_name(const char *name, char *attr_name, int *attr_num)
{
int ret;
ret = strscpy(attr_name, name, ACPI_ATTR_NAME_LEN + 1);
if (ret == -E2BIG)
return kstrtoint(&name[ACPI_ATTR_NAME_LEN + 1], 0, attr_num);
return 0;
}
static ssize_t chromeos_first_level_attr_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
char attr_name[ACPI_ATTR_NAME_LEN + 1];
int ret, attr_num = 0;
ret = parse_attr_name(attr->attr.name, attr_name, &attr_num);
if (ret)
return ret;
return chromeos_acpi_evaluate_method(dev, attr_num, 0, attr_name, buf);
}
static unsigned int get_gpio_pkg_num(struct device *dev)
{
struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
union acpi_object *obj;
acpi_status status;
unsigned int count = 0;
char *name = "GPIO";
status = acpi_evaluate_object(ACPI_HANDLE(dev), name, NULL, &output);
if (ACPI_FAILURE(status)) {
dev_err(dev, "failed to retrieve %s. %s\n", name, acpi_format_exception(status));
return count;
}
obj = output.pointer;
if (obj->type == ACPI_TYPE_PACKAGE)
count = obj->package.count;
kfree(output.pointer);
return count;
}
DEV_ATTR(binf2, BINF.2)
DEV_ATTR(binf3, BINF.3)
DEV_ATTR(chsw, CHSW)
DEV_ATTR(fmap, FMAP)
DEV_ATTR(frid, FRID)
DEV_ATTR(fwid, FWID)
DEV_ATTR(hwid, HWID)
DEV_ATTR(meck, MECK)
DEV_ATTR(vbnv0, VBNV.0)
DEV_ATTR(vbnv1, VBNV.1)
DEV_ATTR(vdat, VDAT)
static struct attribute *first_level_attrs[] = {
&dev_attr_binf2.attr,
&dev_attr_binf3.attr,
&dev_attr_chsw.attr,
&dev_attr_fmap.attr,
&dev_attr_frid.attr,
&dev_attr_fwid.attr,
&dev_attr_hwid.attr,
&dev_attr_meck.attr,
&dev_attr_vbnv0.attr,
&dev_attr_vbnv1.attr,
&dev_attr_vdat.attr,
NULL
};
static const struct attribute_group first_level_attr_group = {
.attrs = first_level_attrs,
};
/*
* Every platform can have a different number of GPIO attribute groups.
* Define upper limit groups. At run time, the platform decides to show
* the present number of groups only, others are hidden.
*/
GPIO_ATTR_GROUP(gpio0, "GPIO.0", 0)
GPIO_ATTR_GROUP(gpio1, "GPIO.1", 1)
GPIO_ATTR_GROUP(gpio2, "GPIO.2", 2)
GPIO_ATTR_GROUP(gpio3, "GPIO.3", 3)
GPIO_ATTR_GROUP(gpio4, "GPIO.4", 4)
GPIO_ATTR_GROUP(gpio5, "GPIO.5", 5)
GPIO_ATTR_GROUP(gpio6, "GPIO.6", 6)
GPIO_ATTR_GROUP(gpio7, "GPIO.7", 7)
static const struct attribute_group *chromeos_acpi_all_groups[] = {
&first_level_attr_group,
&attr_group_gpio0,
&attr_group_gpio1,
&attr_group_gpio2,
&attr_group_gpio3,
&attr_group_gpio4,
&attr_group_gpio5,
&attr_group_gpio6,
&attr_group_gpio7,
NULL
};
static int chromeos_acpi_device_probe(struct platform_device *pdev)
{
chromeos_acpi_gpio_groups = get_gpio_pkg_num(&pdev->dev);
/*
* If the platform has more GPIO attribute groups than the number of
* groups this driver supports, give out a warning message.
*/
if (chromeos_acpi_gpio_groups > ARRAY_SIZE(chromeos_acpi_all_groups) - 2)
dev_warn(&pdev->dev, "Only %zu GPIO attr groups supported by the driver out of total %u.\n",
ARRAY_SIZE(chromeos_acpi_all_groups) - 2, chromeos_acpi_gpio_groups);
return 0;
}
/* GGL is valid PNP ID of Google. PNP ID can be used with the ACPI devices. */
static const struct acpi_device_id chromeos_device_ids[] = {
{ "GGL0001", 0 },
{}
};
MODULE_DEVICE_TABLE(acpi, chromeos_device_ids);
static struct platform_driver chromeos_acpi_device_driver = {
.probe = chromeos_acpi_device_probe,
.driver = {
.name = KBUILD_MODNAME,
.dev_groups = chromeos_acpi_all_groups,
.acpi_match_table = chromeos_device_ids,
}
};
module_platform_driver(chromeos_acpi_device_driver);
MODULE_AUTHOR("Muhammad Usama Anjum <usama.anjum@collabora.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ChromeOS specific ACPI extensions");
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