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// SPDX-License-Identifier: GPL-2.0+
/*
* Thermal sensor subsystem driver for Surface System Aggregator Module (SSAM).
*
* Copyright (C) 2022-2023 Maximilian Luz <luzmaximilian@gmail.com>
*/
#include <linux/bitops.h>
#include <linux/hwmon.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/surface_aggregator/controller.h>
#include <linux/surface_aggregator/device.h>
/* -- SAM interface. -------------------------------------------------------- */
/*
* Available sensors are indicated by a 16-bit bitfield, where a 1 marks the
* presence of a sensor. So we have at most 16 possible sensors/channels.
*/
#define SSAM_TMP_SENSOR_MAX_COUNT 16
/*
* All names observed so far are 6 characters long, but there's only
* zeros after the name, so perhaps they can be longer. This number reflects
* the maximum zero-padded space observed in the returned buffer.
*/
#define SSAM_TMP_SENSOR_NAME_LENGTH 18
struct ssam_tmp_get_name_rsp {
__le16 unknown1;
char unknown2;
char name[SSAM_TMP_SENSOR_NAME_LENGTH];
} __packed;
static_assert(sizeof(struct ssam_tmp_get_name_rsp) == 21);
SSAM_DEFINE_SYNC_REQUEST_CL_R(__ssam_tmp_get_available_sensors, __le16, {
.target_category = SSAM_SSH_TC_TMP,
.command_id = 0x04,
});
SSAM_DEFINE_SYNC_REQUEST_MD_R(__ssam_tmp_get_temperature, __le16, {
.target_category = SSAM_SSH_TC_TMP,
.command_id = 0x01,
});
SSAM_DEFINE_SYNC_REQUEST_MD_R(__ssam_tmp_get_name, struct ssam_tmp_get_name_rsp, {
.target_category = SSAM_SSH_TC_TMP,
.command_id = 0x0e,
});
static int ssam_tmp_get_available_sensors(struct ssam_device *sdev, s16 *sensors)
{
__le16 sensors_le;
int status;
status = __ssam_tmp_get_available_sensors(sdev, &sensors_le);
if (status)
return status;
*sensors = le16_to_cpu(sensors_le);
return 0;
}
static int ssam_tmp_get_temperature(struct ssam_device *sdev, u8 iid, long *temperature)
{
__le16 temp_le;
int status;
status = __ssam_tmp_get_temperature(sdev->ctrl, sdev->uid.target, iid, &temp_le);
if (status)
return status;
/* Convert 1/10 °K to 1/1000 °C */
*temperature = (le16_to_cpu(temp_le) - 2731) * 100L;
return 0;
}
static int ssam_tmp_get_name(struct ssam_device *sdev, u8 iid, char *buf, size_t buf_len)
{
struct ssam_tmp_get_name_rsp name_rsp;
int status;
status = __ssam_tmp_get_name(sdev->ctrl, sdev->uid.target, iid, &name_rsp);
if (status)
return status;
/*
* This should not fail unless the name in the returned struct is not
* null-terminated or someone changed something in the struct
* definitions above, since our buffer and struct have the same
* capacity by design. So if this fails, log an error message. Since
* the more likely cause is that the returned string isn't
* null-terminated, we might have received garbage (as opposed to just
* an incomplete string), so also fail the function.
*/
status = strscpy(buf, name_rsp.name, buf_len);
if (status < 0) {
dev_err(&sdev->dev, "received non-null-terminated sensor name string\n");
return status;
}
return 0;
}
/* -- Driver.---------------------------------------------------------------- */
struct ssam_temp {
struct ssam_device *sdev;
s16 sensors;
char names[SSAM_TMP_SENSOR_MAX_COUNT][SSAM_TMP_SENSOR_NAME_LENGTH];
};
static umode_t ssam_temp_hwmon_is_visible(const void *data,
enum hwmon_sensor_types type,
u32 attr, int channel)
{
const struct ssam_temp *ssam_temp = data;
if (!(ssam_temp->sensors & BIT(channel)))
return 0;
return 0444;
}
static int ssam_temp_hwmon_read(struct device *dev,
enum hwmon_sensor_types type,
u32 attr, int channel, long *value)
{
const struct ssam_temp *ssam_temp = dev_get_drvdata(dev);
return ssam_tmp_get_temperature(ssam_temp->sdev, channel + 1, value);
}
static int ssam_temp_hwmon_read_string(struct device *dev,
enum hwmon_sensor_types type,
u32 attr, int channel, const char **str)
{
const struct ssam_temp *ssam_temp = dev_get_drvdata(dev);
*str = ssam_temp->names[channel];
return 0;
}
static const struct hwmon_channel_info * const ssam_temp_hwmon_info[] = {
HWMON_CHANNEL_INFO(chip,
HWMON_C_REGISTER_TZ),
HWMON_CHANNEL_INFO(temp,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL,
HWMON_T_INPUT | HWMON_T_LABEL),
NULL
};
static const struct hwmon_ops ssam_temp_hwmon_ops = {
.is_visible = ssam_temp_hwmon_is_visible,
.read = ssam_temp_hwmon_read,
.read_string = ssam_temp_hwmon_read_string,
};
static const struct hwmon_chip_info ssam_temp_hwmon_chip_info = {
.ops = &ssam_temp_hwmon_ops,
.info = ssam_temp_hwmon_info,
};
static int ssam_temp_probe(struct ssam_device *sdev)
{
struct ssam_temp *ssam_temp;
struct device *hwmon_dev;
s16 sensors;
int channel;
int status;
status = ssam_tmp_get_available_sensors(sdev, &sensors);
if (status)
return status;
ssam_temp = devm_kzalloc(&sdev->dev, sizeof(*ssam_temp), GFP_KERNEL);
if (!ssam_temp)
return -ENOMEM;
ssam_temp->sdev = sdev;
ssam_temp->sensors = sensors;
/* Retrieve the name for each available sensor. */
for (channel = 0; channel < SSAM_TMP_SENSOR_MAX_COUNT; channel++) {
if (!(sensors & BIT(channel)))
continue;
status = ssam_tmp_get_name(sdev, channel + 1, ssam_temp->names[channel],
SSAM_TMP_SENSOR_NAME_LENGTH);
if (status)
return status;
}
hwmon_dev = devm_hwmon_device_register_with_info(&sdev->dev, "surface_thermal", ssam_temp,
&ssam_temp_hwmon_chip_info, NULL);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct ssam_device_id ssam_temp_match[] = {
{ SSAM_SDEV(TMP, SAM, 0x00, 0x02) },
{ },
};
MODULE_DEVICE_TABLE(ssam, ssam_temp_match);
static struct ssam_device_driver ssam_temp = {
.probe = ssam_temp_probe,
.match_table = ssam_temp_match,
.driver = {
.name = "surface_temp",
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
};
module_ssam_device_driver(ssam_temp);
MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
MODULE_DESCRIPTION("Thermal sensor subsystem driver for Surface System Aggregator Module");
MODULE_LICENSE("GPL");
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