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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: Dave Penkler <dpenkler@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Dave Penkler 2016-01-27 19:19:14 +01:00 committed by Greg Kroah-Hartman
parent 82ed33811d
commit eb6b92ecc0
1 changed files with 23 additions and 0 deletions
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23
drivers/usb/class/usbtmc.c
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@ -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,
};