[PATCH] hwmon: add driver for Aquacomputer Farbwerk 360

[Aleksa Savic <savicaleksa83@gmail.com>]

This driver exposes hardware temperature sensors of the Aquacomputer
Farbwerk 360 RGB controller, which communicates through a proprietary
USB HID protocol.

Four temperature sensors are available. If a sensor is not connected,
it will report zeroes. Additionally, serial number and firmware version
are exposed through debugfs.

This driver has been tested on x86_64.

Signed-off-by: Aleksa Savic <savicaleksa83@gmail.com>
---
 .../hwmon/aquacomputer_farbwerk360.rst        |  40 +++
 Documentation/hwmon/index.rst                 |   1 +
 MAINTAINERS                                   |   7 +
 drivers/hwmon/Kconfig                         |  10 +
 drivers/hwmon/Makefile                        |   1 +
 drivers/hwmon/aquacomputer_farbwerk360.c      | 261 ++++++++++++++++++
 6 files changed, 320 insertions(+)
 create mode 100644 Documentation/hwmon/aquacomputer_farbwerk360.rst
 create mode 100644 drivers/hwmon/aquacomputer_farbwerk360.c

diff --git a/Documentation/hwmon/aquacomputer_farbwerk360.rst b/Documentation/hwmon/aquacomputer_farbwerk360.rst
new file mode 100644
index 000000000000..cebaffccd818
--- /dev/null
+++ b/Documentation/hwmon/aquacomputer_farbwerk360.rst
@@ -0,0 +1,40 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver aquacomputer_farbwerk360
+======================================
+
+Supported devices:
+
+* Aquacomputer Farbwerk 360 RGB controller
+
+Author: Aleksa Savic
+
+Description
+-----------
+
+This driver exposes hardware temperature sensors of the Aquacomputer Farbwerk 360
+RGB controller, which communicates through a proprietary USB HID protocol.
+
+Four temperature sensors are available. If a sensor is not connected, it will report
+zeroes. Additionally, serial number and firmware version are exposed through debugfs.
+
+Usage notes
+-----------
+
+Farbwerk 360 communicates via HID reports. The driver is loaded automatically by
+the kernel and supports hotswapping.
+
+Sysfs entries
+-------------
+
+=============== ==============================================
+temp[1-4]_input Measured temperature (in millidegrees Celsius)
+=============== ==============================================
+
+Debugfs entries
+---------------
+
+================ ===============================================
+serial_number    Serial number of the pump
+firmware_version Version of installed firmware
+================ ===============================================
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index df20022c741f..42b7369340ba 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -40,6 +40,7 @@ Hardware Monitoring Kernel Drivers
    aht10
    amc6821
    aquacomputer_d5next
+   aquacomputer_farbwerk360
    asb100
    asc7621
    aspeed-pwm-tacho
diff --git a/MAINTAINERS b/MAINTAINERS
index bd86ed9fbc79..fb8b8d7aebbc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1386,6 +1386,13 @@ S:	Maintained
 F:	Documentation/hwmon/aquacomputer_d5next.rst
 F:	drivers/hwmon/aquacomputer_d5next.c
 
+AQUACOMPUTER FARBWERK 360 RGB CONTROLLER SENSOR DRIVER
+M:	Aleksa Savic <savicaleksa83@gmail.com>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	Documentation/hwmon/aquacomputer_farbwerk360.rst
+F:	drivers/hwmon/aquacomputer_farbwerk360.c
+
 AQUANTIA ETHERNET DRIVER (atlantic)
 M:	Igor Russkikh <irusskikh@marvell.com>
 L:	netdev@vger.kernel.org
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 8df25f1079ba..e1ca5e1e6ab0 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -264,6 +264,16 @@ config SENSORS_AQUACOMPUTER_D5NEXT
 	  This driver can also be built as a module. If so, the module
 	  will be called aquacomputer_d5next.
 
+config SENSORS_AQUACOMPUTER_FARBWERK360
+	tristate "Aquacomputer Farbwerk 360 RGB controller"
+	depends on USB_HID
+	help
+	  If you say yes here you get support for temperature sensors provided by
+	  the Aquacomputer Farbwerk 360 RGB controller.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called aquacomputer_farbwerk360.
+
 config SENSORS_AS370
 	tristate "Synaptics AS370 SoC hardware monitoring driver"
 	help
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 185f946d698b..1c1556a53f6d 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_SENSORS_ADT7475)	+= adt7475.o
 obj-$(CONFIG_SENSORS_AHT10)	+= aht10.o
 obj-$(CONFIG_SENSORS_APPLESMC)	+= applesmc.o
 obj-$(CONFIG_SENSORS_AQUACOMPUTER_D5NEXT) += aquacomputer_d5next.o
+obj-$(CONFIG_SENSORS_AQUACOMPUTER_FARBWERK360) += aquacomputer_farbwerk360.o
 obj-$(CONFIG_SENSORS_ARM_SCMI)	+= scmi-hwmon.o
 obj-$(CONFIG_SENSORS_ARM_SCPI)	+= scpi-hwmon.o
 obj-$(CONFIG_SENSORS_AS370)	+= as370-hwmon.o
diff --git a/drivers/hwmon/aquacomputer_farbwerk360.c b/drivers/hwmon/aquacomputer_farbwerk360.c
new file mode 100644
index 000000000000..14b760a2c8a8
--- /dev/null
+++ b/drivers/hwmon/aquacomputer_farbwerk360.c
@@ -0,0 +1,261 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * hwmon driver for Aquacomputer Farbwerk 360 (RGB controller)
+ *
+ * The Farbwerk 360 sends HID reports (with ID 0x01) every second to report sensor values
+ * of up to four connected temperature sensors.
+ *
+ * Copyright 2022 Aleksa Savic <savicaleksa83@gmail.com>
+ */
+
+#include <asm/unaligned.h>
+#include <linux/debugfs.h>
+#include <linux/hid.h>
+#include <linux/hwmon.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+
+#define DRIVER_NAME		"aquacomputer_farbwerk360"
+
+#define STATUS_REPORT_ID	0x01
+#define STATUS_UPDATE_INTERVAL	(2 * HZ) /* In seconds */
+
+/* Register offsets */
+#define SERIAL_FIRST_PART	0x03
+#define SERIAL_SECOND_PART	0x05
+#define FIRMWARE_VERSION	0x0D
+
+#define NUM_SENSORS		4
+#define SENSOR_START		0x32
+#define SENSOR_SIZE		0x02
+#define SENSOR_DISCONNECTED	0x7FFF
+
+static const char *const label_temps[] = { "Sensor 1", "Sensor 2", "Sensor 3", "Sensor 4" };
+
+struct farbwerk360_data {
+	struct hid_device *hdev;
+	struct device *hwmon_dev;
+	struct dentry *debugfs;
+	s32 temp_input[4];
+	u32 serial_number[2];
+	u16 firmware_version;
+	unsigned long updated;
+};
+
+static umode_t farbwerk360_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
+				      int channel)
+{
+	return 0444;
+}
+
+static int farbwerk360_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
+			    long *val)
+{
+	struct farbwerk360_data *priv = dev_get_drvdata(dev);
+
+	if (time_after(jiffies, priv->updated + STATUS_UPDATE_INTERVAL))
+		return -ENODATA;
+
+	switch (type) {
+	case hwmon_temp:
+		*val = priv->temp_input[channel];
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int farbwerk360_read_string(struct device *dev, enum hwmon_sensor_types type, u32 attr,
+				   int channel, const char **str)
+{
+	switch (type) {
+	case hwmon_temp:
+		*str = label_temps[channel];
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static const struct hwmon_ops farbwerk360_hwmon_ops = {
+	.is_visible = farbwerk360_is_visible,
+	.read = farbwerk360_read,
+	.read_string = farbwerk360_read_string,
+};
+
+static const struct hwmon_channel_info *farbwerk360_info[] = {
+	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),
+	NULL
+};
+
+static const struct hwmon_chip_info farbwerk360_chip_info = {
+	.ops = &farbwerk360_hwmon_ops,
+	.info = farbwerk360_info,
+};
+
+static int farbwerk360_raw_event(struct hid_device *hdev, struct hid_report *report, u8 *data,
+				 int size)
+{
+	int i, sensor_value;
+	struct farbwerk360_data *priv;
+
+	if (report->id != STATUS_REPORT_ID)
+		return 0;
+
+	priv = hid_get_drvdata(hdev);
+
+	/* Info provided with every report */
+	priv->serial_number[0] = get_unaligned_be16(data + SERIAL_FIRST_PART);
+	priv->serial_number[1] = get_unaligned_be16(data + SERIAL_SECOND_PART);
+
+	priv->firmware_version = get_unaligned_be16(data + FIRMWARE_VERSION);
+
+	/* Temperature sensor readings */
+	for (i = 0; i < NUM_SENSORS; i++) {
+		sensor_value = get_unaligned_be16(data + SENSOR_START + i * SENSOR_SIZE);
+		if (sensor_value == SENSOR_DISCONNECTED)
+			sensor_value = 0;
+
+		priv->temp_input[i] = sensor_value * 10;
+	}
+
+	priv->updated = jiffies;
+
+	return 0;
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+static int serial_number_show(struct seq_file *seqf, void *unused)
+{
+	struct farbwerk360_data *priv = seqf->private;
+
+	seq_printf(seqf, "%05u-%05u\n", priv->serial_number[0], priv->serial_number[1]);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(serial_number);
+
+static int firmware_version_show(struct seq_file *seqf, void *unused)
+{
+	struct farbwerk360_data *priv = seqf->private;
+
+	seq_printf(seqf, "%u\n", priv->firmware_version);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(firmware_version);
+
+static void farbwerk360_debugfs_init(struct farbwerk360_data *priv)
+{
+	char name[32];
+
+	scnprintf(name, sizeof(name), "%s-%s", DRIVER_NAME, dev_name(&priv->hdev->dev));
+
+	priv->debugfs = debugfs_create_dir(name, NULL);
+	debugfs_create_file("serial_number", 0444, priv->debugfs, priv, &serial_number_fops);
+	debugfs_create_file("firmware_version", 0444, priv->debugfs, priv, &firmware_version_fops);
+}
+
+#else
+
+static void farbwerk360_debugfs_init(struct farbwerk360_data *priv)
+{
+}
+
+#endif
+
+static int farbwerk360_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+	struct farbwerk360_data *priv;
+
+	priv = devm_kzalloc(&hdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->hdev = hdev;
+	hid_set_drvdata(hdev, priv);
+
+	priv->updated = jiffies - STATUS_UPDATE_INTERVAL;
+
+	ret = hid_parse(hdev);
+	if (ret)
+		return ret;
+
+	ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
+	if (ret)
+		return ret;
+
+	ret = hid_hw_open(hdev);
+	if (ret)
+		goto fail_and_stop;
+
+	priv->hwmon_dev = hwmon_device_register_with_info(&hdev->dev, "farbwerk360", priv,
+							  &farbwerk360_chip_info, NULL);
+
+	if (IS_ERR(priv->hwmon_dev)) {
+		ret = PTR_ERR(priv->hwmon_dev);
+		goto fail_and_close;
+	}
+
+	farbwerk360_debugfs_init(priv);
+
+	return 0;
+
+fail_and_close:
+	hid_hw_close(hdev);
+fail_and_stop:
+	hid_hw_stop(hdev);
+	return ret;
+}
+
+static void farbwerk360_remove(struct hid_device *hdev)
+{
+	struct farbwerk360_data *priv = hid_get_drvdata(hdev);
+
+	debugfs_remove_recursive(priv->debugfs);
+	hwmon_device_unregister(priv->hwmon_dev);
+
+	hid_hw_close(hdev);
+	hid_hw_stop(hdev);
+}
+
+static const struct hid_device_id farbwerk360_table[] = {
+	{ HID_USB_DEVICE(0x0c70, 0xf010) }, /* Aquacomputer Farbwerk 360 */
+	{},
+};
+
+MODULE_DEVICE_TABLE(hid, farbwerk360_table);
+
+static struct hid_driver farbwerk360_driver = {
+	.name = DRIVER_NAME,
+	.id_table = farbwerk360_table,
+	.probe = farbwerk360_probe,
+	.remove = farbwerk360_remove,
+	.raw_event = farbwerk360_raw_event,
+};
+
+static int __init farbwerk360_init(void)
+{
+	return hid_register_driver(&farbwerk360_driver);
+}
+
+static void __exit farbwerk360_exit(void)
+{
+	hid_unregister_driver(&farbwerk360_driver);
+}
+
+/* Request to initialize after the HID bus to ensure it's not being loaded before */
+late_initcall(farbwerk360_init);
+module_exit(farbwerk360_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Aleksa Savic <savicaleksa83@gmail.com>");
+MODULE_DESCRIPTION("Hwmon driver for Aquacomputer Farbwerk 360");
-- 
2.35.1