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authorDave Penkler <dpenkler@gmail.com>2016-01-27 19:19:14 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-03 22:54:06 +0100
commiteb6b92ecc0f9412623ab1584ddd8389b371638d4 (patch)
treea40c07fb2e27cd39999d235993142ec17391978d /drivers/usb/class
parentAdd support for USBTMC USB488 SRQ notification with fasync (diff)
downloadlinux-eb6b92ecc0f9412623ab1584ddd8389b371638d4.tar.xz
linux-eb6b92ecc0f9412623ab1584ddd8389b371638d4.zip
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>
Diffstat (limited to 'drivers/usb/class')
-rw-r--r--drivers/usb/class/usbtmc.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index d77da2fd7b70..867842951ea0 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -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,
};