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Add support for USBTMC USB488 SRQ notification with fasync 

Background:
By configuring an instrument's event status register various
conditions can be reported via an SRQ notification. This complements
the synchronous polling approach using the READ_STATUS_BYTE ioctl
with an asynchronous notification.

Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dave Penkler 2016-01-27 19:15:15 +01:00 committed by Greg Kroah-Hartman
parent dbf3e7f654
commit 82ed33811d
1 changed files with 24 additions and 0 deletions
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24
drivers/usb/class/usbtmc.c
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@ -99,6 +99,7 @@ struct usbtmc_device_data {
int iin_interval;
struct urb *iin_urb;
u16 iin_wMaxPacketSize;
atomic_t srq_asserted;
u8 rigol_quirk;
@ -113,6 +114,7 @@ struct usbtmc_device_data {
struct kref kref;
struct mutex io_mutex; /* only one i/o function running at a time */
wait_queue_head_t waitq;
struct fasync_struct *fasync;
};
#define to_usbtmc_data(d) container_of(d, struct usbtmc_device_data, kref)
@ -405,6 +407,9 @@ static int usbtmc488_ioctl_read_stb(struct usbtmc_device_data *data,
atomic_set(&data->iin_data_valid, 0);
/* must issue read_stb before using poll or select */
atomic_set(&data->srq_asserted, 0);
rv = usb_control_msg(data->usb_dev,
usb_rcvctrlpipe(data->usb_dev, 0),
USBTMC488_REQUEST_READ_STATUS_BYTE,
@ -1172,6 +1177,13 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
return retval;
}
static int usbtmc_fasync(int fd, struct file *file, int on)
{
struct usbtmc_device_data *data = file->private_data;
return fasync_helper(fd, file, on, &data->fasync);
}
static const struct file_operations fops = {
.owner = THIS_MODULE,
.read = usbtmc_read,
@ -1179,6 +1191,7 @@ static const struct file_operations fops = {
.open = usbtmc_open,
.release = usbtmc_release,
.unlocked_ioctl = usbtmc_ioctl,
.fasync = usbtmc_fasync,
.llseek = default_llseek,
};
@ -1208,6 +1221,16 @@ static void usbtmc_interrupt(struct urb *urb)
wake_up_interruptible(&data->waitq);
goto exit;
}
/* check for SRQ notification */
if (data->iin_buffer[0] == 0x81) {
if (data->fasync)
kill_fasync(&data->fasync,
SIGIO, POLL_IN);
atomic_set(&data->srq_asserted, 1);
wake_up_interruptible(&data->waitq);
goto exit;
}
dev_warn(dev, "invalid notification: %x\n", data->iin_buffer[0]);
break;
case -EOVERFLOW:
@ -1263,6 +1286,7 @@ static int usbtmc_probe(struct usb_interface *intf,
mutex_init(&data->io_mutex);
init_waitqueue_head(&data->waitq);
atomic_set(&data->iin_data_valid, 0);
atomic_set(&data->srq_asserted, 0);
data->zombie = 0;
/* Determine if it is a Rigol or not */