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Date:   Wed, 15 Jul 2020 07:39:14 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Marius Zachmann <mail@mariuszachmann.de>
Cc:     Jean Delvare <jdelvare@suse.com>, Jonathan Corbet <corbet@lwn.net>,
        linux-hwmon@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] hwmon: corsair-cpro: Change to hid driver
Message-ID: <20200715143914.GB201840@roeck-us.net>
References: <20200714105230.3126-1-mail@mariuszachmann.de>
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On Tue, Jul 14, 2020 at 12:52:30PM +0200, Marius Zachmann wrote:
> I found a project which uses hidraw to communicate with the device.
> Because I do not want to break any existing userspace code, I
> changed this to a hid driver, so hidraw can still be used.
> Do I need to include the hid maintainers for the undo in hid-quirks?

I think I'll squash this patch with the others.

> 
> Signed-off-by: Marius Zachmann <mail@mariuszachmann.de>
> ---
>  drivers/hid/hid-quirks.c     |   2 -
>  drivers/hwmon/Kconfig        |   4 +-
>  drivers/hwmon/corsair-cpro.c | 114 ++++++++++++++++++++++++++---------
>  3 files changed, 86 insertions(+), 34 deletions(-)
> 
> diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
> index 7b7bc7737c53..ca8b5c261c7c 100644
> --- a/drivers/hid/hid-quirks.c
> +++ b/drivers/hid/hid-quirks.c
> @@ -699,8 +699,6 @@ static const struct hid_device_id hid_ignore_list[] = {
>  	{ HID_USB_DEVICE(USB_VENDOR_ID_AXENTIA, USB_DEVICE_ID_AXENTIA_FM_RADIO) },
>  	{ HID_USB_DEVICE(USB_VENDOR_ID_BERKSHIRE, USB_DEVICE_ID_BERKSHIRE_PCWD) },
>  	{ HID_USB_DEVICE(USB_VENDOR_ID_CIDC, 0x0103) },
> -	{ HID_USB_DEVICE(USB_VENDOR_ID_CORSAIR, 0x0c10) },
> -	{ HID_USB_DEVICE(USB_VENDOR_ID_CORSAIR, 0x1d00) },
>  	{ HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL, USB_DEVICE_ID_CYGNAL_RADIO_SI470X) },
>  	{ HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL, USB_DEVICE_ID_CYGNAL_RADIO_SI4713) },
>  	{ HID_USB_DEVICE(USB_VENDOR_ID_CMEDIA, USB_DEVICE_ID_CM109) },
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 8b046a5dfa40..c603d8c8e3d2 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -441,7 +441,7 @@ config SENSORS_BT1_PVT_ALARMS
> 
>  config SENSORS_CORSAIR_CPRO
>  	tristate "Corsair Commander Pro controller"
> -	depends on USB
> +	depends on HID
>  	help
>  	  If you say yes here you get support for the Corsair Commander Pro
>  	  controller.
> @@ -1716,7 +1716,7 @@ config SENSORS_ADS7871
> 
>  config SENSORS_AMC6821
>  	tristate "Texas Instruments AMC6821"
> -	depends on I2C
> +	depends on I2C

Unrelated change; please drop.

>  	help
>  	  If you say yes here you get support for the Texas Instruments
>  	  AMC6821 hardware monitoring chips.
> diff --git a/drivers/hwmon/corsair-cpro.c b/drivers/hwmon/corsair-cpro.c
> index fe625190e3a1..4310ee5aca24 100644
> --- a/drivers/hwmon/corsair-cpro.c
> +++ b/drivers/hwmon/corsair-cpro.c
> @@ -5,13 +5,14 @@
>   */
> 
>  #include <linux/bitops.h>
> +#include <linux/completion.h>
> +#include <linux/hid.h>
>  #include <linux/hwmon.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  #include <linux/slab.h>
>  #include <linux/types.h>
> -#include <linux/usb.h>
> 
>  #define USB_VENDOR_ID_CORSAIR			0x1b1c
>  #define USB_PRODUCT_ID_CORSAIR_COMMANDERPRO	0x0c10
> @@ -62,7 +63,8 @@
>  #define NUM_TEMP_SENSORS	4
> 
>  struct ccp_device {
> -	struct usb_device *udev;
> +	struct hid_device *hdev;
> +	struct completion wait_input_report;
>  	struct mutex mutex; /* whenever buffer is used, lock before send_usb_cmd */
>  	u8 *buffer;
>  	int pwm[6];
> @@ -75,7 +77,7 @@ struct ccp_device {
>  /* send command, check for error in response, response in ccp->buffer */
>  static int send_usb_cmd(struct ccp_device *ccp, u8 command, u8 byte1, u8 byte2, u8 byte3)
>  {
> -	int actual_length;
> +	unsigned long t;
>  	int ret;
> 
>  	memset(ccp->buffer, 0x00, OUT_BUFFER_SIZE);
> @@ -84,26 +86,39 @@ static int send_usb_cmd(struct ccp_device *ccp, u8 command, u8 byte1, u8 byte2,
>  	ccp->buffer[2] = byte2;
>  	ccp->buffer[3] = byte3;
> 
> -	ret = usb_bulk_msg(ccp->udev, usb_sndintpipe(ccp->udev, 2), ccp->buffer, OUT_BUFFER_SIZE,
> -			   &actual_length, 1000);
> -	if (ret)
> -		return ret;
> +	reinit_completion(&ccp->wait_input_report);
> 
> -	/* response needs to be received every time */
> -	ret = usb_bulk_msg(ccp->udev, usb_rcvintpipe(ccp->udev, 1), ccp->buffer, IN_BUFFER_SIZE,
> -			   &actual_length, 1000);
> -	if (ret)
> +	ret = hid_hw_output_report(ccp->hdev, ccp->buffer, OUT_BUFFER_SIZE);
> +	if (ret < 0)
>  		return ret;
> 
> +	t = wait_for_completion_timeout(&ccp->wait_input_report, msecs_to_jiffies(300));

Please use a define for the timeout.

> +	if (!t)
> +		return -ETIMEDOUT;


> +
>  	/* first byte of response is error code */
>  	if (ccp->buffer[0] != 0x00) {
> -		dev_dbg(&ccp->udev->dev, "device response error: %d", ccp->buffer[0]);
> +		hid_dbg(ccp->hdev, "device response error: %d", ccp->buffer[0]);
>  		return -EIO;
>  	}
> 
>  	return 0;
>  }
> 
> +static int ccp_raw_event(struct hid_device *hdev, struct hid_report *report, u8 *data, int size)
> +{
> +	struct ccp_device *ccp = hid_get_drvdata(hdev);
> +
> +	/* only copy buffer when requested */
> +	if (completion_done(&ccp->wait_input_report))
> +		return 0;
> +
> +	memcpy(ccp->buffer, data, min(IN_BUFFER_SIZE, size));
> +	complete(&ccp->wait_input_report);
> +
> +	return 0;
> +}
> +
>  /* requests and returns single data values depending on channel */
>  static int get_data(struct ccp_device *ccp, int command, int channel)
>  {
> @@ -437,57 +452,96 @@ static int get_temp_cnct(struct ccp_device *ccp)
>  	return 0;
>  }
> 
> -static int ccp_probe(struct usb_interface *intf, const struct usb_device_id *id)
> +static int ccp_probe(struct hid_device *hdev, const struct hid_device_id *id)
>  {
>  	struct device *hwmon_dev;
>  	struct ccp_device *ccp;
>  	int ret;
> 
> -	ccp = devm_kzalloc(&intf->dev, sizeof(*ccp), GFP_KERNEL);
> +	ccp = devm_kzalloc(&hdev->dev, sizeof(*ccp), GFP_KERNEL);
>  	if (!ccp)
>  		return -ENOMEM;
> 
> -	ccp->buffer = devm_kmalloc(&intf->dev, OUT_BUFFER_SIZE, GFP_KERNEL);
> +	ccp->buffer = devm_kmalloc(&hdev->dev, OUT_BUFFER_SIZE, GFP_KERNEL);
>  	if (!ccp->buffer)
>  		return -ENOMEM;
> 
> +	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 out_hw_stop;
> +
> +	ccp->hdev = hdev;
> +	hid_set_drvdata(hdev, ccp);
>  	mutex_init(&ccp->mutex);
> +	init_completion(&ccp->wait_input_report);
> 
> -	ccp->udev = interface_to_usbdev(intf);
> +	hid_device_io_start(hdev);
> 
>  	/* temp and fan connection status only updates when device is powered on */
>  	ret = get_temp_cnct(ccp);
>  	if (ret)
> -		return ret;
> +		goto out_hw_close;
> 
>  	ret = get_fan_cnct(ccp);
>  	if (ret)
> -		return ret;
> -
> -	hwmon_dev = devm_hwmon_device_register_with_info(&intf->dev, "corsaircpro", ccp,
> +		goto out_hw_close;
> +	hwmon_dev = devm_hwmon_device_register_with_info(&hdev->dev, "corsaircpro", ccp,
>  							 &ccp_chip_info, 0);

You'll have to use hwmon_device_register_with_info() and call the remove
function explicitly in ccp_remove() to avoid race conditions.
Alternatively, you could use devm_add_action_or_reset() to handle
hid_hw_close() and hid_hw_stop(), but that would probably not be worth
the added complexity.

> +	if (IS_ERR(hwmon_dev)) {
> +		ret = PTR_ERR(hwmon_dev);
> +		goto out_hw_close;
> +	}
> +
> +	return 0;
> 
> -	return PTR_ERR_OR_ZERO(hwmon_dev);
> +out_hw_close:
> +	hid_hw_close(hdev);
> +out_hw_stop:
> +	hid_hw_stop(hdev);
> +	return ret;
>  }
> 
> -static void ccp_disconnect(struct usb_interface *intf)
> +static void ccp_remove(struct hid_device *hdev)
>  {
> +	hid_hw_close(hdev);
> +	hid_hw_stop(hdev);
>  }
> 
> -static const struct usb_device_id ccp_devices[] = {
> -	{ USB_DEVICE(USB_VENDOR_ID_CORSAIR, USB_PRODUCT_ID_CORSAIR_COMMANDERPRO) },
> -	{ USB_DEVICE(USB_VENDOR_ID_CORSAIR, USB_PRODUCT_ID_CORSAIR_1000D) },
> +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 usb_driver ccp_driver = {
> +static struct hid_driver ccp_driver = {
>  	.name = "corsair-cpro",
> +	.id_table = ccp_devices,
>  	.probe = ccp_probe,
> -	.disconnect = ccp_disconnect,
> -	.id_table = ccp_devices
> +	.remove = ccp_remove,
> +	.raw_event = ccp_raw_event,
>  };
> 
> -MODULE_DEVICE_TABLE(usb, ccp_devices);
> +MODULE_DEVICE_TABLE(hid, ccp_devices);
>  MODULE_LICENSE("GPL");
> 
> -module_usb_driver(ccp_driver);
> +static int __init ccp_init(void)
> +{
> +	return hid_register_driver(&ccp_driver);
> +}
> +
> +static void __exit ccp_exit(void)
> +{
> +	hid_unregister_driver(&ccp_driver);
> +}
> +
> +/* make sure, it is loaded after hid */
> +late_initcall(ccp_init);
> +module_exit(ccp_exit);
> --
> 2.27.0