linux-kernel - Re: [PATCH v5 1/3] mfd: ch341: add core driver for the WCH CH341 in I2C/SPI/GPIO mode

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Message-ID: <Youukx+7oieeDVCE@hovoldconsulting.com>
Date:   Mon, 23 May 2022 17:56:03 +0200
From:   Johan Hovold <johan@...nel.org>
To:     frank zago <frank@...o.net>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Wolfram Sang <wsa@...nel.org>, linux-usb@...r.kernel.org,
        Lee Jones <lee.jones@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org
Subject: Re: [PATCH v5 1/3] mfd: ch341: add core driver for the WCH CH341 in
 I2C/SPI/GPIO mode

On Thu, Mar 31, 2022 at 09:33:04PM -0500, frank zago wrote:
> The CH341 is a multifunction chip, presenting 3 different USB PID. One
> of these functions is for I2C/SPI/GPIO. This new set of drivers will
> manage I2C and GPIO.
> 
> Signed-off-by: frank zago <frank@...o.net>
> ---

> +static int ch341_usb_probe(struct usb_interface *iface,
> +			   const struct usb_device_id *usb_id)
> +{
> +	struct usb_host_endpoint *endpoints;
> +	struct ch341_device *dev;
> +	int rc;
> +
> +	dev = devm_kzalloc(&iface->dev, sizeof(*dev), GFP_KERNEL);
> +	if (!dev)
> +		return -ENOMEM;
> +
> +	dev->usb_dev = usb_get_dev(interface_to_usbdev(iface));

No need to grab a reference unless you're going to hold on to it past
disconnect().

> +	dev->iface = iface;
> +	mutex_init(&dev->usb_lock);
> +
> +	if (iface->cur_altsetting->desc.bNumEndpoints != 3) {
> +		rc = -ENODEV;
> +		goto free_dev;
> +	}
> +
> +	endpoints = iface->cur_altsetting->endpoint;
> +	if (!usb_endpoint_is_bulk_in(&endpoints[0].desc) ||
> +	    !usb_endpoint_is_bulk_out(&endpoints[1].desc) ||
> +	    !usb_endpoint_xfer_int(&endpoints[2].desc)) {
> +		rc = -ENODEV;
> +		goto free_dev;
> +	}

Please use usb_find_common_endpoints() for the above.

> +
> +	dev->ep_in = endpoints[0].desc.bEndpointAddress;
> +	dev->ep_out = endpoints[1].desc.bEndpointAddress;
> +	dev->ep_intr = endpoints[2].desc.bEndpointAddress;
> +	dev->ep_intr_interval = endpoints[2].desc.bInterval;
> +
> +	usb_set_intfdata(iface, dev);
> +
> +	rc = mfd_add_hotplug_devices(&iface->dev, ch341_devs,
> +				     ARRAY_SIZE(ch341_devs));
> +	if (rc) {
> +		rc = dev_err_probe(&iface->dev, rc,
> +				   "Failed to add mfd devices to core\n");
> +		goto free_dev;
> +	}
> +
> +	return 0;
> +
> +free_dev:
> +	usb_put_dev(dev->usb_dev);
> +
> +	return rc;
> +}
> +
> +static void ch341_usb_disconnect(struct usb_interface *usb_if)
> +{
> +	struct ch341_device *dev = usb_get_intfdata(usb_if);
> +
> +	mfd_remove_devices(&usb_if->dev);
> +	usb_put_dev(dev->usb_dev);
> +}

Johan