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Commit eb6b92ec authored by Dave Penkler's avatar Dave Penkler Committed by Greg Kroah-Hartman
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Add support for receiving USBTMC USB488 SRQ notifications via poll/select 



Background:
In many situations operations on multiple instruments need to be
synchronized. poll/select provide a convenient way of waiting on a
number of different instruments and other peripherals
simultaneously.

Signed-off-by: default avatarDave Penkler <dpenkler@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 82ed3381

drivers/usb/class/usbtmc.c

+23 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/uaccess.h>

#include <linux/kref.h>

#include <linux/slab.h>

#include <linux/poll.h>

#include <linux/mutex.h>

#include <linux/usb.h>

#include <linux/usb/tmc.h>
@@ -1184,6 +1185,27 @@ static int usbtmc_fasync(int fd, struct file *file, int on) 
	return fasync_helper(fd, file, on, &data->fasync);

}



static unsigned int usbtmc_poll(struct file *file, poll_table *wait)

{

	struct usbtmc_device_data *data = file->private_data;

	unsigned int mask;



	mutex_lock(&data->io_mutex);



	if (data->zombie) {

		mask = POLLHUP | POLLERR;

		goto no_poll;

	}



	poll_wait(file, &data->waitq, wait);



	mask = (atomic_read(&data->srq_asserted)) ? POLLIN | POLLRDNORM : 0;



no_poll:

	mutex_unlock(&data->io_mutex);

	return mask;

}



static const struct file_operations fops = {

	.owner		= THIS_MODULE,

	.read		= usbtmc_read,
@@ -1192,6 +1214,7 @@ static const struct file_operations fops = { 
	.release	= usbtmc_release,

	.unlocked_ioctl	= usbtmc_ioctl,

	.fasync         = usbtmc_fasync,

	.poll           = usbtmc_poll,

	.llseek		= default_llseek,

};