[PATCH v4 3/5] Add support for receiving USBTMC USB488 SRQ notifications via poll/select

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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@xxxxxxxxx>
---
 drivers/usb/class/usbtmc.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 7430a52..6c0e1dc 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>
@@ -1189,6 +1190,27 @@ 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,
@@ -1197,6 +1219,7 @@ static const struct file_operations fops = {
 	.release	= usbtmc_release,
 	.unlocked_ioctl	= usbtmc_ioctl,
 	.fasync         = usbtmc_fasync,
+	.poll           = usbtmc_poll,
 	.llseek		= default_llseek,
 };
 
-- 
2.5.1
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux