On 12/28/23 01:34, Ivor Wanders wrote:
Adds a driver that provides read only access to the fan speed for Microsoft
Surface Pro devices. The fan speed is always regulated by the EC and cannot
be influenced directly.
Signed-off-by: Ivor Wanders <ivor@xxxxxxxxxxxx>
Link: https://github.com/linux-surface/kernel/pull/144
---
Changes in v2:
- Removed all sysfs attributes except fan1_input. Simplified code
and updated documentation accordingly.
---
Documentation/hwmon/index.rst | 1 +
Documentation/hwmon/surface_fan.rst | 25 +++++++
MAINTAINERS | 8 +++
drivers/hwmon/Kconfig | 13 ++++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/surface_fan.c | 105 ++++++++++++++++++++++++++++
6 files changed, 153 insertions(+)
create mode 100644 Documentation/hwmon/surface_fan.rst
create mode 100644 drivers/hwmon/surface_fan.c
[...]
diff --git a/drivers/hwmon/surface_fan.c b/drivers/hwmon/surface_fan.c
new file mode 100644
index 000000000..0160a585c
--- /dev/null
+++ b/drivers/hwmon/surface_fan.c
@@ -0,0 +1,105 @@
+// 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@xxxxxxxxxxxx>
+ */
+
+#include <linux/hwmon.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
As far as I can see, linux/platform_device.h is not needed.
Regards,
Max
+#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
+umode_t surface_fan_hwmon_is_visible(const void *drvdata,
+ enum hwmon_sensor_types type, u32 attr,
+ int channel)
+{
+ if (type != hwmon_fan)
+ return 0;
+
+ if (attr != hwmon_fan_input)
+ return 0;
+
+ 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);
+ __le16 value;
+
+ if (type != hwmon_fan)
+ return -EOPNOTSUPP;
+
+ if (attr != hwmon_fan_input)
+ return -EOPNOTSUPP;
+
+ if (__ssam_fan_rpm_get(sdev, &value))
+ return -EIO;
+
+ *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, "fan", sdev,
+ &surface_fan_chip_info,
+ NULL);
+ if (IS_ERR(hdev))
+ return PTR_ERR(hdev);
+
+ ssam_device_set_drvdata(sdev, sdev);
+
+ return 0;
+}
+
+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@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Fan Driver for Surface System Aggregator Module");
+MODULE_LICENSE("GPL");
