On Wed, Jun 10, 2020 at 12:26:40AM +0200, Marius Zachmann wrote:
> 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.
> 
The above should be limited to the driver description. Discussion should be
below the '---'. Either case, make sure to split your lines.

> Signed-off-by: Marius Zachmann <m...@mariuszachmann.de>
> ---
>  Documentation/hwmon/corsair-cpro.rst |  42 +++

Needs to be added to Documentation/hwmon/index.rst.

>  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
> +
Index starts with 1 for everything except inX.

> +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 <m...@mariuszachmann.de>
> +L:   linux-hw...@vger.kernel.org
> +S:   Maintained
> +F:   drivers/hwmon/corsair-cpro.c
> +
>  COSA/SRP SYNC SERIAL DRIVER
>  M:   Jan "Yenya" Kasprzak <k...@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

This conflicts with MODULE_LICENSE which explicitly states GPL v2.

> +/*
> + * corsair-cpro.c - Linux driver for Corsair Commander Pro
> + * Copyright (C) 2020 Marius Zachmann <m...@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)

Unnecessary line break.

> +
> +#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 */
> +

Please use tabs consistently after the defined name, eg

#define OUT_BUFFER_SIZE 63
#define IN_BUFFER_SIZE  16
#define LABEL_LENGTH    10

> +struct ccp_device {
> +     struct hid_device *hdev;
> +     struct device *hwmondev;

Not used anywhere.

> +     struct mutex mutex;
> +     int pwm[6];
> +     int fan_enable[6];
> +     char fan_label[6][LABEL_LENGTH];
> +

Unnecessary empty line.

> +};
> +
> +/* 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;
> +
> +
Unnecessary empty line

> +     mutex_lock(&ccp->mutex);
> +
> +     ret = usb_bulk_msg(udev,
> +                     usb_sndintpipe(udev, 2),
> +                     buffer,
> +                     OUT_BUFFER_SIZE,
> +                     &actual_length,
> +                     1000);

Too many line breaks. All over the place. Please only split lines where
necessary (line length limit is now 100).

> +     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;

Unnecessary initialization (almost everywhere).

> +     u8 *buffer;
> +
> +     buffer = kzalloc(OUT_BUFFER_SIZE, GFP_KERNEL);
> +     if (buffer == 0)
> +             return -ENOMEM;

AFAICS all those commands end up locking anyway. Might as well
move the buffer into struct ccp_device and use it from there
(ie lock while using it).

> +
> +     buffer[0] = command;
> +     buffer[1] = channel;
> +     ret = send_usb_cmd(ccp, buffer);
> +     if (ret)
> +             return -EIO;

Please do not replace error codes - not just here, everywhere.

> +
> +     *val = (buffer[1] << 8) + buffer[2];
> +
> +     kfree(buffer);
> +     return ret;

Just return 0;

> +}
> +
> +static int set_pwm(struct ccp_device *ccp, int channel, long val)
> +{
> +     int ret = 0;
> +     u8 *buffer;
> +
> +     if (val > 255)
> +             return -EINVAL;

How about val < 0 ?

> +
> +     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;

        val = DIV_ROUND_CLOSEST(val * 100, 255);

would be much easier to read.

> +
> +     buffer = kzalloc(OUT_BUFFER_SIZE, GFP_KERNEL);
> +     if (buffer == 0)

        if (!buffer)
> +             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];

Space around operators (use checkpatch --strict to find all locations).

> +
> +     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);

If this is an error that needs to be logged you have to return an error.
I would suggest to name the label something like "fanX other" instead
in this situation.

> +             break;
> +     }
> +
> +exit:
> +     kfree(buffer);
> +     return ret == 0 ? 0 : -EIO;

While it is unacceptable, I am curious why you override error codes everywhere.

> +}
> +
> +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)

Valid values are 0 and 1, so != 1 is unnecessary. Use
        if (!ccp->fan_enable[channel])
instead.

> +             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];

This returns 0 if pwm wasn't set. Is this indeed not readable from the
device ?

> +                     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;

Needs to be validated. Accepting random values does not make sense here.

> +                     break;
> +             default:
> +                     ret = -EINVAL;

-EOPNOTSUPP for those cases.

> +                     break;
> +             }
> +             break;
> +     case hwmon_pwm:
> +             switch (attr) {
> +             case hwmon_pwm_input:
> +                     set_pwm(ccp, channel, val);

Do not ignore errors.

> +                     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;

                default:

missing everywhere here.

> +             }
> +             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,
> +


Another unnecessary empty line.

> +};
> +
> +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;

                return ret;

> +     }
> +
> +     ccp = devm_kzalloc(&hdev->dev, sizeof(struct ccp_device), GFP_KERNEL);
> +     if (ccp == NULL)
> +             goto exit;

                return -ENOMEM;

> +
> +     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);

This can return an ERR_PTR.

> +
> +exit:
> +     return ret;
> +}
> +
> +static void ccp_remove(struct hid_device *hdev)
> +{
> +     struct ccp_device *ccp;
> +
> +     ccp = hid_get_drvdata(hdev);
> +     mutex_destroy(&ccp->mutex);

The memory is about to be released, so this doesn't really add value.
Just drop the remove function and forget about mutex_destroy().

> +}
> +
> +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
> 
> 

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