[RFC] drivers/hwmon: Corsair Commander Pro driver

[Marius Zachmann <mail@mariuszachmann.de>]

This is a driver for the Corsair Commander Pro.
Since this is my first addition to the kernel I would be happy, if you would take a look at it.
I am using this driver on my computer at home and I had a few people test it.

The device:

The Corsair Commander Pro is a USB device, which is usually connected on the internal USB headers on the mainboard.
It has 6 fan connectors, 4 thermal sensor connectors and 2 RGB connectors.
It also reads the voltages on the SATA connector, which it needs for power.

The driver:

I hope hwmon is the right place.
The driver is a HID driver, but it uses usb_bulk_msg for communication.
The device registers as a HID device and there are userspace tools, which use hidraw to access it. I think, it would be good to maintain compatibility with these tools, but the driver can easily be rewritten to be a pure USB driver.
For now it can read temp sensors, fan speeds, voltage values and set pwm values.
It also reads the connection status on the fan headers.

There are a few more things, which I would like to add in the near future:
* Fan curves (not yet sure about the nicest way to provide sysfs access)
* Force 3pin or 4pin mode. (Sometimes the device doesn't detect the fans correctly)
* Setting fixed RPM

I do not work for Corsair and I intend to keep the driver maintainted as long as I use the device privately.

Signed-off-by: Marius Zachmann <mail@mariuszachmann.de>
---
 Documentation/hwmon/corsair-cpro.rst |  42 +++
 MAINTAINERS                          |   6 +
 drivers/hwmon/Kconfig                |  10 +
 drivers/hwmon/Makefile               |   1 +
 drivers/hwmon/corsair-cpro.c         | 481 +++++++++++++++++++++++++++
 5 files changed, 540 insertions(+)
 create mode 100644 Documentation/hwmon/corsair-cpro.rst
 create mode 100644 drivers/hwmon/corsair-cpro.c

diff --git a/Documentation/hwmon/corsair-cpro.rst b/Documentation/hwmon/corsair-cpro.rst
new file mode 100644
index 000000000000..d4ea1b6b9336
--- /dev/null
+++ b/Documentation/hwmon/corsair-cpro.rst
@@ -0,0 +1,42 @@
+Kernel driver corsair-cpro
+==========================
+
+Supported devices:
+
+  * Corsair Commander Pro
+  * Corsair Commander Pro (1000D)
+
+Author: Marius Zachmann
+
+Description
+-----------
+
+This driver implements the sysfs interface for the Corsair Commander Pro.
+The Corsair Commander Pro is a USB device with 6 fan connectors,
+4 temperature sensor connectors and 2 Corsair LED connectors.
+It can read the voltage levels on the SATA power connector.
+
+Usage Notes
+-----------
+
+Since it is a USB device, hotswapping is possible. The device is autodetected.
+
+Sysfs entries
+-------------
+
+in0_input		Voltage on SATA 12v
+in1_input		Voltage on SATA 5v
+in2_input		Voltage on SATA 3.3v
+
+temp[0-3]_input		Connected temperature sensors
+
+fan[0-5]_input		Connected fan rpm.
+fan[0-5]_label		Shows connection status of the fan as detected by the
+			device.
+			"fanX nc"   no connection
+			"fanX 3pin" 3-pin fan detected
+			"fanX 4pin" 4-pin fan detected
+fan[0-5]_enable		the driver only reports fan speeds when 1
+pwm[0-5]		Sets the fan speed. Values from 0-255.
+			When reading, it reports the last value, which
+			was set by the driver.
diff --git a/MAINTAINERS b/MAINTAINERS
index f08f290df174..169530c7eede 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4386,6 +4386,12 @@ S:	Maintained
 F:	Documentation/hwmon/coretemp.rst
 F:	drivers/hwmon/coretemp.c
 
+CORSAIR-CPRO HARDWARE MONITOR DRIVER
+M:	Marius Zachmann <mail@mariuszachmann.de>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	drivers/hwmon/corsair-cpro.c
+
 COSA/SRP SYNC SERIAL DRIVER
 M:	Jan "Yenya" Kasprzak <kas@fi.muni.cz>
 S:	Maintained
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 288ae9f63588..9f5a808768ca 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -439,6 +439,16 @@ config SENSORS_BT1_PVT_ALARMS
 	  the data conversion will be periodically performed and the data will be
 	  saved in the internal driver cache.
 
+config SENSORS_CORSAIR_CPRO
+	tristate "Corsair Commander Pro controller"
+	depends on USB_HID
+	help
+	  If you say yes here you get support for the Corsair Commander Pro
+	  controller.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called corsair-cpro.
+
 config SENSORS_DRIVETEMP
 	tristate "Hard disk drives with temperature sensors"
 	depends on SCSI && ATA
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 3e32c21f5efe..18e1ef74ade7 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_SENSORS_ATXP1)	+= atxp1.o
 obj-$(CONFIG_SENSORS_AXI_FAN_CONTROL) += axi-fan-control.o
 obj-$(CONFIG_SENSORS_BT1_PVT)	+= bt1-pvt.o
 obj-$(CONFIG_SENSORS_CORETEMP)	+= coretemp.o
+obj-$(CONFIG_SENSORS_CORSAIR_CPRO) += corsair-cpro.o
 obj-$(CONFIG_SENSORS_DA9052_ADC)+= da9052-hwmon.o
 obj-$(CONFIG_SENSORS_DA9055)+= da9055-hwmon.o
 obj-$(CONFIG_SENSORS_DELL_SMM)	+= dell-smm-hwmon.o
diff --git a/drivers/hwmon/corsair-cpro.c b/drivers/hwmon/corsair-cpro.c
new file mode 100644
index 000000000000..8ba7fb061184
--- /dev/null
+++ b/drivers/hwmon/corsair-cpro.c
@@ -0,0 +1,481 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * corsair-cpro.c - Linux driver for Corsair Commander Pro
+ * Copyright (C) 2020 Marius Zachmann <mail@mariuszachmann.de>
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/hid.h>
+#include <linux/hwmon.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#define	hid_to_usb_dev(hid_dev) \
+	to_usb_device(hid_dev->dev.parent->parent)
+
+#define USB_VENDOR_ID_CORSAIR               0x1b1c
+#define USB_PRODUCT_ID_CORSAIR_COMMANDERPRO 0x0c10
+#define USB_PRODUCT_ID_CORSAIR_1000D	    0x1d00
+
+#define OUT_BUFFER_SIZE 63
+#define IN_BUFFER_SIZE 16
+#define LABEL_LENGTH 10
+
+#define CTL_GET_TMP	 0x11  /* byte 1 is channel, rest zero              */
+			       /* returns temp for channel in bytes 1 and 2 */
+#define CTL_GET_VOLT	 0x12  /* byte 1 = rail number 12, 5, 3.3 */
+			       /* returns volt in bytes 1,2       */
+#define CTL_GET_FAN_CNCT 0x20  /* returns in bytes 1-6   */
+			       /* 0 for no connect       */
+			       /* 1 for 3pin, 2 for 4pin */
+#define CTL_GET_FAN_RPM	 0x21  /* works like CTL_GET_TMP */
+#define CTL_SET_FAN_FPWM 0x23  /* byte 1 is fan number              */
+			       /* byte 2 is percentage from 0 - 100 */
+
+struct ccp_device {
+	struct hid_device *hdev;
+	struct device *hwmondev;
+	struct mutex mutex;
+	int pwm[6];
+	int fan_enable[6];
+	char fan_label[6][LABEL_LENGTH];
+
+};
+
+/* send 63 byte buffer and receive response in same buffer */
+static int send_usb_cmd(struct ccp_device *ccp, u8 *buffer)
+{
+	int ret;
+	struct usb_device *udev = hid_to_usb_dev(ccp->hdev);
+	int actual_length;
+
+
+	mutex_lock(&ccp->mutex);
+
+	ret = usb_bulk_msg(udev,
+			usb_sndintpipe(udev, 2),
+			buffer,
+			OUT_BUFFER_SIZE,
+			&actual_length,
+			1000);
+	if (ret < 0) {
+		hid_err(ccp->hdev,
+			"usb_bulk_msg send failed: %d", ret);
+		goto exit;
+	}
+
+	ret = usb_bulk_msg(udev,
+			usb_rcvintpipe(udev, 1),
+			buffer,
+			IN_BUFFER_SIZE,
+			&actual_length,
+			1000);
+	if (ret) {
+		hid_err(ccp->hdev,
+			"usb_bulk_msg receive failed: %d", ret);
+		goto exit;
+	}
+
+exit:
+	mutex_unlock(&ccp->mutex);
+	return ret;
+}
+
+/* for commands, which return just a number depending on a channel: */
+/* get_temp, get_volt, get_fan_rpm */
+static int get_data(struct ccp_device *ccp, int command, int channel, long *val)
+{
+	int ret = 0;
+	u8 *buffer;
+
+	buffer = kzalloc(OUT_BUFFER_SIZE, GFP_KERNEL);
+	if (buffer == 0)
+		return -ENOMEM;
+
+	buffer[0] = command;
+	buffer[1] = channel;
+	ret = send_usb_cmd(ccp, buffer);
+	if (ret)
+		return -EIO;
+
+	*val = (buffer[1] << 8) + buffer[2];
+
+	kfree(buffer);
+	return ret;
+}
+
+static int set_pwm(struct ccp_device *ccp, int channel, long val)
+{
+	int ret = 0;
+	u8 *buffer;
+
+	if (val > 255)
+		return -EINVAL;
+
+	ccp->pwm[channel] = val;
+
+	/* The Corsair Commander Pro uses values from 0-100 */
+	val = val << 8;
+	val = val / 255;
+	val = val * 100;
+	val = val >> 8;
+
+	buffer = kzalloc(OUT_BUFFER_SIZE, GFP_KERNEL);
+	if (buffer == 0)
+		return -ENOMEM;
+
+	buffer[0] = CTL_SET_FAN_FPWM;
+	buffer[1] = channel;
+	buffer[2] = val;
+	ret = send_usb_cmd(ccp, buffer);
+
+	kfree(buffer);
+	return ret == 0 ? 0 : -EIO;
+}
+
+static int get_fan_mode_label(struct ccp_device *ccp, int channel)
+{
+	int ret = 0;
+	int mode;
+	u8 *buffer;
+
+	buffer = kzalloc(OUT_BUFFER_SIZE, GFP_KERNEL);
+	if (buffer == 0)
+		return -ENOMEM;
+
+	buffer[0] = CTL_GET_FAN_CNCT;
+	ret = send_usb_cmd(ccp, buffer);
+	if (ret)
+		goto exit;
+
+	mode = buffer[channel+1];
+
+	switch (mode) {
+	case 0:
+		scnprintf(ccp->fan_label[channel], LABEL_LENGTH,
+			  "fan%d nc", channel+1);
+		break;
+	case 1:
+		scnprintf(ccp->fan_label[channel], LABEL_LENGTH,
+			  "fan%d 3pin", channel+1);
+		break;
+	case 2:
+		scnprintf(ccp->fan_label[channel], LABEL_LENGTH,
+			  "fan%d 4pin", channel+1);
+		break;
+	default:
+		dev_err(&ccp->hdev->dev,
+			"Mode Description %d not implemented", mode);
+		break;
+	}
+
+exit:
+	kfree(buffer);
+	return ret == 0 ? 0 : -EIO;
+}
+
+static int get_voltages(struct ccp_device *ccp, int channel, long *val)
+{
+	int ret = 0;
+
+	ret = get_data(ccp, CTL_GET_VOLT, channel, val);
+
+	return ret == 0 ? 0 : -EIO;
+}
+
+static int get_temp(struct ccp_device *ccp, int channel, long *val)
+{
+	int ret = 0;
+
+	ret = get_data(ccp, CTL_GET_TMP, channel, val);
+	*val = *val * 10;
+
+	return ret == 0 ? 0 : -EIO;
+}
+
+static int get_rpm(struct ccp_device *ccp, int channel, long *val)
+{
+	int ret = 0;
+
+	if (ccp->fan_enable[channel] != 1)
+		return -ENODATA;
+
+	ret = get_data(ccp, CTL_GET_FAN_RPM, channel, val);
+
+	return ret == 0 ? 0 : -EIO;
+}
+
+static int ccp_read_string(struct device *dev, enum hwmon_sensor_types type,
+			   u32 attr, int channel, const char **str)
+{
+	int ret = 0;
+	struct ccp_device *ccp = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_label:
+			ret = get_fan_mode_label(ccp, channel);
+			*str = ccp->fan_label[channel];
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static int ccp_read(struct device *dev, enum hwmon_sensor_types type,
+		    u32 attr, int channel, long *val)
+{
+	int ret = 0;
+	struct ccp_device *ccp = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+			ret = get_temp(ccp, channel, val);
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+			ret = get_rpm(ccp, channel, val);
+			break;
+		case hwmon_fan_enable:
+			*val = ccp->fan_enable[channel];
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+			*val = ccp->pwm[channel];
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	case hwmon_in:
+		switch (attr) {
+		case hwmon_in_input:
+			ret = get_voltages(ccp, channel, val);
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	return ret;
+};
+
+static int ccp_write(struct device *dev, enum hwmon_sensor_types type,
+		     u32 attr, int channel, long val)
+{
+	int ret = 0;
+	struct ccp_device *ccp = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_enable:
+			ccp->fan_enable[channel] = val;
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+			set_pwm(ccp, channel, val);
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	return ret;
+};
+
+static umode_t ccp_is_visible(const void *data, enum hwmon_sensor_types type,
+			      u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_chip:
+		switch (attr) {
+		case hwmon_chip_update_interval:
+			return 0644;
+		}
+		break;
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+			return 0444;
+		}
+		break;
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+			return 0444;
+		case hwmon_fan_label:
+			return 0444;
+		case hwmon_fan_enable:
+			return 0644;
+		}
+		break;
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+			return 0644;
+		}
+		break;
+	case hwmon_in:
+		switch (attr) {
+		case hwmon_in_input:
+			return 0444;
+		}
+		break;
+	default:
+		break;
+	}
+	return 0;
+};
+
+static const struct hwmon_ops ccp_hwmon_ops = {
+	.is_visible = ccp_is_visible,
+	.read = ccp_read,
+	.write = ccp_write,
+	.read_string = ccp_read_string,
+};
+
+static const struct hwmon_channel_info *ccp_info[] = {
+	HWMON_CHANNEL_INFO(chip,
+			   HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_MAX,
+			   HWMON_T_INPUT | HWMON_T_MAX,
+			   HWMON_T_INPUT | HWMON_T_MAX,
+			   HWMON_T_INPUT | HWMON_T_MAX
+			   ),
+	HWMON_CHANNEL_INFO(fan,
+			   HWMON_F_INPUT | HWMON_F_ENABLE | HWMON_F_LABEL,
+			   HWMON_F_INPUT | HWMON_F_ENABLE | HWMON_F_LABEL,
+			   HWMON_F_INPUT | HWMON_F_ENABLE | HWMON_F_LABEL,
+			   HWMON_F_INPUT | HWMON_F_ENABLE | HWMON_F_LABEL,
+			   HWMON_F_INPUT | HWMON_F_ENABLE | HWMON_F_LABEL,
+			   HWMON_F_INPUT | HWMON_F_ENABLE | HWMON_F_LABEL
+			   ),
+	HWMON_CHANNEL_INFO(pwm,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT
+			   ),
+	HWMON_CHANNEL_INFO(in,
+			   HWMON_I_INPUT,
+			   HWMON_I_INPUT,
+			   HWMON_I_INPUT
+			   ),
+	NULL
+};
+
+static const struct hwmon_chip_info ccp_chip_info = {
+	.ops = &ccp_hwmon_ops,
+	.info = ccp_info,
+
+};
+
+static int ccp_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	struct ccp_device *ccp;
+	int ret = 0;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "hid_parse failed\n");
+		goto exit;
+	}
+
+	ccp = devm_kzalloc(&hdev->dev, sizeof(struct ccp_device), GFP_KERNEL);
+	if (ccp == NULL)
+		goto exit;
+
+	mutex_init(&ccp->mutex);
+
+	ccp->fan_enable[0] = 1;
+	ccp->fan_enable[1] = 1;
+	ccp->fan_enable[2] = 1;
+	ccp->fan_enable[3] = 1;
+	ccp->fan_enable[4] = 1;
+	ccp->fan_enable[5] = 1;
+
+	hid_set_drvdata(hdev, ccp);
+
+	ccp->hdev = hdev;
+	ccp->hwmondev = devm_hwmon_device_register_with_info(&hdev->dev,
+				"corsaircpro",
+				ccp,
+				&ccp_chip_info,
+				0);
+
+exit:
+	return ret;
+}
+
+static void ccp_remove(struct hid_device *hdev)
+{
+	struct ccp_device *ccp;
+
+	ccp = hid_get_drvdata(hdev);
+	mutex_destroy(&ccp->mutex);
+}
+
+static const struct hid_device_id ccp_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CORSAIR,
+			 USB_PRODUCT_ID_CORSAIR_COMMANDERPRO) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CORSAIR,
+			 USB_PRODUCT_ID_CORSAIR_1000D) },
+	{ }
+};
+
+static struct hid_driver ccp_driver = {
+	.name = "corsair-cpro",
+	.id_table = ccp_devices,
+	.probe = ccp_probe,
+	.remove = ccp_remove
+};
+
+MODULE_DEVICE_TABLE(hid, ccp_devices);
+MODULE_LICENSE("GPL v2");
+
+module_hid_driver(ccp_driver);
-- 
2.27.0