From eb6b92ecc0f9412623ab1584ddd8389b371638d4 Mon Sep 17 00:00:00 2001 From: Dave Penkler Date: Wed, 27 Jan 2016 19:19:14 +0100 Subject: 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 Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/usbtmc.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'drivers/usb/class/usbtmc.c') 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 #include #include +#include #include #include #include @@ -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, }; -- cgit