diff options
Diffstat (limited to 'drivers/hwmon/surface_temp.c')
| -rw-r--r-- | drivers/hwmon/surface_temp.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/drivers/hwmon/surface_temp.c b/drivers/hwmon/surface_temp.c new file mode 100644 index 000000000000..cd21f331f157 --- /dev/null +++ b/drivers/hwmon/surface_temp.c @@ -0,0 +1,235 @@ +// 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"); |