diff options
| author | Dave Penkler <dpenkler@gmail.com> | 2016-01-27 21:19:14 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-04 00:54:06 +0300 |
| commit | eb6b92ecc0f9412623ab1584ddd8389b371638d4 (patch) | |
| tree | a40c07fb2e27cd39999d235993142ec17391978d /drivers/usb/class/usbtmc.c | |
| parent | 82ed33811d7214198e071b785ee34dbe99f82140 (diff) | |
| download | linux-eb6b92ecc0f9412623ab1584ddd8389b371638d4.tar.xz | |
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/usbtmc.c')
| -rw-r--r-- | drivers/usb/class/usbtmc.c | 23 |
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, }; |