1 files changed, 91 insertions, 0 deletions
diff --git a/drivers/hwmon/surface_fan.c b/drivers/hwmon/surface_fan.c
new file mode 100644
index 0000000000..de3c5a2409
--- /dev/null
+++ b/drivers/hwmon/surface_fan.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Surface Fan driver for Surface System Aggregator Module. It provides access
+ * to the fan's rpm through the hwmon system.
+ *
+ * Copyright (C) 2023 Ivor Wanders <ivor@iwanders.net>
+ */
+
+#include <linux/hwmon.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/surface_aggregator/device.h>
+#include <linux/types.h>
+
+// SSAM
+SSAM_DEFINE_SYNC_REQUEST_CL_R(__ssam_fan_rpm_get, __le16, {
+	.target_category = SSAM_SSH_TC_FAN,
+	.command_id      = 0x01,
+});
+
+// hwmon
+static umode_t surface_fan_hwmon_is_visible(const void *drvdata,
+					    enum hwmon_sensor_types type, u32 attr,
+					    int channel)
+{
+	return 0444;
+}
+
+static int surface_fan_hwmon_read(struct device *dev,
+				  enum hwmon_sensor_types type, u32 attr,
+				  int channel, long *val)
+{
+	struct ssam_device *sdev = dev_get_drvdata(dev);
+	int ret;
+	__le16 value;
+
+	ret = __ssam_fan_rpm_get(sdev, &value);
+	if (ret)
+		return ret;
+
+	*val = le16_to_cpu(value);
+
+	return 0;
+}
+
+static const struct hwmon_channel_info *const surface_fan_info[] = {
+	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
+	NULL
+};
+
+static const struct hwmon_ops surface_fan_hwmon_ops = {
+	.is_visible = surface_fan_hwmon_is_visible,
+	.read = surface_fan_hwmon_read,
+};
+
+static const struct hwmon_chip_info surface_fan_chip_info = {
+	.ops = &surface_fan_hwmon_ops,
+	.info = surface_fan_info,
+};
+
+static int surface_fan_probe(struct ssam_device *sdev)
+{
+	struct device *hdev;
+
+	hdev = devm_hwmon_device_register_with_info(&sdev->dev,
+						    "surface_fan", sdev,
+						    &surface_fan_chip_info,
+						    NULL);
+
+	return PTR_ERR_OR_ZERO(hdev);
+}
+
+static const struct ssam_device_id ssam_fan_match[] = {
+	{ SSAM_SDEV(FAN, SAM, 0x01, 0x01) },
+	{},
+};
+MODULE_DEVICE_TABLE(ssam, ssam_fan_match);
+
+static struct ssam_device_driver surface_fan = {
+	.probe = surface_fan_probe,
+	.match_table = ssam_fan_match,
+	.driver = {
+		.name = "surface_fan",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+module_ssam_device_driver(surface_fan);
+
+MODULE_AUTHOR("Ivor Wanders <ivor@iwanders.net>");
+MODULE_DESCRIPTION("Fan Driver for Surface System Aggregator Module");
+MODULE_LICENSE("GPL");