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Date: Sun, 29 Nov 2015 13:34:03 +0100 From: Dave Penkler <dpenkler@...il.com> To: gregkh@...uxfoundation.org Cc: peter.chen@...escale.com, teuniz@...il.com, linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH v6 3/5] 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@...il.com> --- 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 7bfd6ec..3b85ef5 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> @@ -1183,6 +1184,27 @@ 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, @@ -1191,6 +1213,7 @@ static const struct file_operations fops = { .release = usbtmc_release, .unlocked_ioctl = usbtmc_ioctl, .fasync = usbtmc_fasync, + .poll = usbtmc_poll, .llseek = default_llseek, }; -- 2.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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