--- /dev/null
+// 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");
projects / users / jedix / linux-maple.git / commitdiff