diff options
| author | Guido Kiener <guido@kiener-muenchen.de> | 2018-09-12 10:50:54 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-20 13:04:02 +0200 |
| commit | bb99794a4792068cb4bfd40e99e0f9d8fe7872fa (patch) | |
| tree | 47cf633743de2d9bddba4066aba56dfd22abdfc8 /include/uapi/linux/usb/tmc.h | |
| parent | b14984518ee60ef7662aa6520b76ae6046e08857 (diff) | |
usb: usbtmc: Add ioctl for vendor specific read
The USBTMC_IOCTL_READ call provides for generic synchronous and
asynchronous reads on bulk IN to implement vendor specific library
routines.
Depending on transfer_size the function submits one or more urbs (up
to 16) each with a size of up to 4kB.
The flag USBTMC_FLAG_IGNORE_TRAILER can be used when the transmission
size is already known. Then the function does not truncate the
transfer_size to a multiple of 4 kB, but does reserve extra space
to receive the final short or zero length packet. Note that the
instrument is allowed to send up to wMaxPacketSize - 1 bytes at the
end of a message to avoid sending a zero length packet.
With flag USBTMC_FLAG_ASYNC the ioctl is non blocking. When no
received data is available, the read function submits as many urbs as
needed to receive transfer_size bytes. However the number of flying
urbs (=4kB) is limited to 16 even with subsequent calls of this ioctl.
Returns -EAGAIN when non blocking and no data is received.
Signals EPOLLIN | EPOLLRDNORM when asynchronous urbs are ready to
be read.
In non blocking mode the usbtmc_message.message pointer may be NULL
and the ioctl just submits urbs to initiate receiving data. However if
data is already available due to a previous non blocking call the ioctl
will return -EINVAL when the message pointer is NULL.
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>
Diffstat (limited to 'include/uapi/linux/usb/tmc.h')
| -rw-r--r-- | include/uapi/linux/usb/tmc.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/uapi/linux/usb/tmc.h b/include/uapi/linux/usb/tmc.h index 0166ba5452d5..f0fd0d4334ec 100644 --- a/include/uapi/linux/usb/tmc.h +++ b/include/uapi/linux/usb/tmc.h @@ -64,6 +64,7 @@ struct usbtmc_termchar { */ #define USBTMC_FLAG_ASYNC 0x0001 #define USBTMC_FLAG_APPEND 0x0002 +#define USBTMC_FLAG_IGNORE_TRAILER 0x0004 struct usbtmc_message { __u32 transfer_size; /* size of bytes to transfer */ @@ -86,6 +87,7 @@ struct usbtmc_message { #define USBTMC_IOCTL_EOM_ENABLE _IOW(USBTMC_IOC_NR, 11, __u8) #define USBTMC_IOCTL_CONFIG_TERMCHAR _IOW(USBTMC_IOC_NR, 12, struct usbtmc_termchar) #define USBTMC_IOCTL_WRITE _IOWR(USBTMC_IOC_NR, 13, struct usbtmc_message) +#define USBTMC_IOCTL_READ _IOWR(USBTMC_IOC_NR, 14, struct usbtmc_message) #define USBTMC_IOCTL_WRITE_RESULT _IOWR(USBTMC_IOC_NR, 15, __u32) #define USBTMC488_IOCTL_GET_CAPS _IOR(USBTMC_IOC_NR, 17, unsigned char) |