usb: usbtmc: Add ioctl for generic requests on control

Add USBTMC_IOCTL_CTRL_REQUEST to send arbitrary requests on the
control pipe.  Used by specific applications of IVI Foundation,
Inc. to implement VISA API functions: viUsbControlIn/Out.

The maximum length of control request is set to 4k.

This ioctl does not support compatibility for 32 bit
applications running on 64 bit systems. However all other
convenient ioctls of the USBTMC driver can still be used in 32
bit applications as well. Note that 32 bit applications running
on 32 bit target systems are not affected by this limitation.

Signed-off-by: Guido Kiener <guido.kiener@rohde-schwarz.com>
Reviewed-by: Steve Bayless <steve_bayless@keysight.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 69 insertions, 0 deletions

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 83ffa5a14c3d..7e69bd05c631 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2007 Stefan Kopp, Gechingen, Germany
  * Copyright (C) 2008 Novell, Inc.
  * Copyright (C) 2008 Greg Kroah-Hartman <gregkh@suse.de>
+ * Copyright (C) 2018 IVI Foundation, Inc.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -36,6 +37,9 @@
 /* Default USB timeout (in milliseconds) */
 #define USBTMC_TIMEOUT		5000
 
+/* I/O buffer size used in generic read/write functions */
+#define USBTMC_BUFSIZE		(4096)
+
 /*
  * Maximum number of read cycles to empty bulk in endpoint during CLEAR and
  * ABORT_BULK_IN requests. Ends the loop if (for whatever reason) a short
@@ -1250,6 +1254,67 @@ exit:
 	return rv;
 }
 
+static int usbtmc_ioctl_request(struct usbtmc_device_data *data,
+				void __user *arg)
+{
+	struct device *dev = &data->intf->dev;
+	struct usbtmc_ctrlrequest request;
+	u8 *buffer = NULL;
+	int rv;
+	unsigned long res;
+
+	res = copy_from_user(&request, arg, sizeof(struct usbtmc_ctrlrequest));
+	if (res)
+		return -EFAULT;
+
+	buffer = kmalloc(request.req.wLength, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	if (request.req.wLength > USBTMC_BUFSIZE)
+		return -EMSGSIZE;
+
+	if (request.req.wLength) {
+		buffer = kmalloc(request.req.wLength, GFP_KERNEL);
+		if (!buffer)
+			return -ENOMEM;
+
+		if ((request.req.bRequestType & USB_DIR_IN) == 0) {
+			/* Send control data to device */
+			res = copy_from_user(buffer, request.data,
+					     request.req.wLength);
+			if (res) {
+				rv = -EFAULT;
+				goto exit;
+			}
+		}
+	}
+
+	rv = usb_control_msg(data->usb_dev,
+			usb_rcvctrlpipe(data->usb_dev, 0),
+			request.req.bRequest,
+			request.req.bRequestType,
+			request.req.wValue,
+			request.req.wIndex,
+			buffer, request.req.wLength, USB_CTRL_GET_TIMEOUT);
+
+	if (rv < 0) {
+		dev_err(dev, "%s failed %d\n", __func__, rv);
+		goto exit;
+	}
+
+	if (rv && (request.req.bRequestType & USB_DIR_IN)) {
+		/* Read control data from device */
+		res = copy_to_user(request.data, buffer, rv);
+		if (res)
+			rv = -EFAULT;
+	}
+
+ exit:
+	kfree(buffer);
+	return rv;
+}
+
 /*
  * Get the usb timeout value
  */
@@ -1366,6 +1431,10 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		retval = usbtmc_ioctl_abort_bulk_in(data);
 		break;
 
+	case USBTMC_IOCTL_CTRL_REQUEST:
+		retval = usbtmc_ioctl_request(data, (void __user *)arg);
+		break;
+
 	case USBTMC_IOCTL_GET_TIMEOUT:
 		retval = usbtmc_ioctl_get_timeout(file_data,
 						  (void __user *)arg);