Add ioctl to retrieve USBTMC-USB488 capabilities

This is a convenience function to obtain an instrument's
capabilities from its file descriptor without having to access sysfs
from the user program.

Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 867842951ea0..6edb21ca9989 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -102,6 +102,9 @@ struct usbtmc_device_data {
         u16            iin_wMaxPacketSize;
         atomic_t       srq_asserted;
 
+        /* coalesced usb488_caps from usbtmc_dev_capabilities */
+        __u8 usb488_caps;
+
         u8 rigol_quirk;
 
         /* attributes from the USB TMC spec for this device */
@@ -993,6 +996,7 @@ static int get_capabilities(struct usbtmc_device_data *data)
         data->capabilities.device_capabilities = buffer[5];
         data->capabilities.usb488_interface_capabilities = buffer[14];
         data->capabilities.usb488_device_capabilities = buffer[15];
+        data->usb488_caps = (buffer[14] & 0x07) | ((buffer[15] & 0x0f) << 4);
         rv = 0;
 
 err_out:
@@ -1168,6 +1172,14 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 retval = usbtmc_ioctl_abort_bulk_in(data);
                 break;
 
+        case USBTMC488_IOCTL_GET_CAPS:
+                retval = copy_to_user((void __user *)arg,
+                                &data->usb488_caps,
+                                sizeof(data->usb488_caps));
+                if (retval)
+                        retval = -EFAULT;
+                break;
+
         case USBTMC488_IOCTL_READ_STB:
                 retval = usbtmc488_ioctl_read_stb(data, (void __user *)arg);
                 break;