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// SPDX-License-Identifier: GPL-2.0-only
/*
* Read-only fan monitoring for the HONOR FMI-XX.
*
* The firmware-provided \GFNS ACPI method accepts a three-byte buffer.
* Byte 2 selects fan 0 or 1. It returns a status byte followed by a
* little-endian 16-bit fan speed in RPM. The method owns all Embedded
* Controller access and serialization; this driver deliberately exposes no
* fan control interface.
*/
#include <linux/acpi.h>
#include <linux/dmi.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#define HONOR_FMI_GFNS_RESULT_SIZE 3
struct honor_fmi_data {
acpi_handle gfns;
};
static const struct dmi_system_id honor_fmi_dmi_table[] = {
{
.matches = {
DMI_MATCH(DMI_SYS_VENDOR, "HONOR"),
DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "FMI-XX"),
},
},
{}
};
MODULE_DEVICE_TABLE(dmi, honor_fmi_dmi_table);
static int honor_fmi_read_rpm(struct honor_fmi_data *data, int channel,
long *rpm)
{
union acpi_object input = {
.buffer = {
.type = ACPI_TYPE_BUFFER,
.length = 3,
},
};
struct acpi_object_list arguments = {
.count = 1,
.pointer = &input,
};
struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
union acpi_object *result;
u8 input_bytes[3] = { 0, 0, channel };
acpi_status status;
int ret = 0;
input.buffer.pointer = input_bytes;
status = acpi_evaluate_object(data->gfns, NULL, &arguments, &output);
if (ACPI_FAILURE(status))
return -EIO;
result = output.pointer;
if (!result || result->type != ACPI_TYPE_BUFFER ||
result->buffer.length < HONOR_FMI_GFNS_RESULT_SIZE) {
ret = -EPROTO;
goto out_free;
}
if (result->buffer.pointer[0]) {
ret = -EIO;
goto out_free;
}
*rpm = result->buffer.pointer[1] |
(result->buffer.pointer[2] << 8);
out_free:
kfree(output.pointer);
return ret;
}
static umode_t honor_fmi_is_visible(const void *data,
enum hwmon_sensor_types type, u32 attr,
int channel)
{
return 0444;
}
static int honor_fmi_read(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long *value)
{
struct honor_fmi_data *data = dev_get_drvdata(dev);
return honor_fmi_read_rpm(data, channel, value);
}
static const struct hwmon_ops honor_fmi_hwmon_ops = {
.is_visible = honor_fmi_is_visible,
.read = honor_fmi_read,
};
static const struct hwmon_channel_info * const honor_fmi_hwmon_info[] = {
HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT, HWMON_F_INPUT),
NULL
};
static const struct hwmon_chip_info honor_fmi_chip_info = {
.ops = &honor_fmi_hwmon_ops,
.info = honor_fmi_hwmon_info,
};
static int honor_fmi_probe(struct platform_device *pdev)
{
struct honor_fmi_data *data;
struct device *hwmon_dev;
acpi_status status;
if (!dmi_check_system(honor_fmi_dmi_table))
return -ENODEV;
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
status = acpi_get_handle(NULL, "\\GFNS", &data->gfns);
if (ACPI_FAILURE(status))
return dev_err_probe(&pdev->dev, -ENODEV,
"firmware does not provide \\GFNS\n");
hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, "honor_fmi",
data,
&honor_fmi_chip_info,
NULL);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static struct platform_driver honor_fmi_driver = {
.probe = honor_fmi_probe,
.driver = {
.name = "honor-fmi-hwmon",
},
};
static struct platform_device *honor_fmi_device;
static int __init honor_fmi_init(void)
{
int ret;
if (!dmi_check_system(honor_fmi_dmi_table))
return -ENODEV;
ret = platform_driver_register(&honor_fmi_driver);
if (ret)
return ret;
honor_fmi_device = platform_device_register_simple("honor-fmi-hwmon",
PLATFORM_DEVID_NONE,
NULL, 0);
if (IS_ERR(honor_fmi_device)) {
platform_driver_unregister(&honor_fmi_driver);
return PTR_ERR(honor_fmi_device);
}
return 0;
}
static void __exit honor_fmi_exit(void)
{
platform_device_unregister(honor_fmi_device);
platform_driver_unregister(&honor_fmi_driver);
}
module_init(honor_fmi_init);
module_exit(honor_fmi_exit);
MODULE_AUTHOR("Nikita Dubrovskih <testname142@gmail.com>");
MODULE_DESCRIPTION("HONOR FMI-XX fan speed monitor");
MODULE_LICENSE("GPL");
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