diff options
| author | Dave Penkler <dpenkler@gmail.com> | 2020-12-15 16:56:20 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-12-28 15:50:30 +0100 |
| commit | d1d9defdc6d582119d29f5d88f810b72bb1837fa (patch) | |
| tree | f3dce4bbad4c77f09e8d3876602afd8f81171e86 /drivers/usb/class/usbtmc.c | |
| parent | c9784e23c1020e63d6dba5e10ca8bf3d8b85c19c (diff) | |
USB: usbtmc: Add separate USBTMC_IOCTL_GET_SRQ_STB
This new ioctl only returns the status byte (STB) that was originally
sent by the device due to a service request (SRQ) condition.
This ioctl checks the srq_asserted bit of the associated file
descriptor. If set, the srq_asserted bit is reset and the cached
STB with original SRQ information is returned. Otherwise the ioctl
returns the error code ENOMSG.
This ioctl is useful to support non USBTMC-488 compliant devices.
Time sensitive applications can read the cached STB without incurring
the cost of an urb transaction over the bus.
Tested-by: Jian-Wei Wu <jian-wei_wu@keysight.com>
Reviewed-by: Guido Kiener <guido.kiener@rohde-schwarz.com>
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20201215155621.9592-4-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 | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c index 8918e2182eca..d2fcc698c745 100644 --- a/drivers/usb/class/usbtmc.c +++ b/drivers/usb/class/usbtmc.c @@ -571,6 +571,32 @@ static int usbtmc488_ioctl_read_stb(struct usbtmc_file_data *file_data, } +static int usbtmc_ioctl_get_srq_stb(struct usbtmc_file_data *file_data, + void __user *arg) +{ + struct usbtmc_device_data *data = file_data->data; + struct device *dev = &data->intf->dev; + int srq_asserted = 0; + __u8 stb = 0; + int rv; + + spin_lock_irq(&data->dev_lock); + srq_asserted = atomic_xchg(&file_data->srq_asserted, srq_asserted); + + if (srq_asserted) { + stb = file_data->srq_byte; + spin_unlock_irq(&data->dev_lock); + rv = put_user(stb, (__u8 __user *)arg); + } else { + spin_unlock_irq(&data->dev_lock); + rv = -ENOMSG; + } + + dev_dbg(dev, "stb:0x%02x with srq received %d\n", (unsigned int)stb, rv); + + return rv; +} + static int usbtmc488_ioctl_wait_srq(struct usbtmc_file_data *file_data, __u32 __user *arg) { @@ -2155,6 +2181,11 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg) retval = put_user(tmp_byte, (__u8 __user *)arg); break; + case USBTMC_IOCTL_GET_SRQ_STB: + retval = usbtmc_ioctl_get_srq_stb(file_data, + (void __user *)arg); + break; + case USBTMC_IOCTL_CANCEL_IO: retval = usbtmc_ioctl_cancel_io(file_data); break; |