[03/12] usb: usbtmc: Add ioctls to set/get usb timeout

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, May 17, 2018 at 07:03:27PM +0200, Guido Kiener wrote:
> Add ioctls USBTMC_IOCTL_GET_TIMEOUT / USBTMC_IOCTL_SET_TIMEOUT to
> get/set I/O timeout for specific file handle.
> 
> Different operations on an instrument can take different lengths of
> time thus it is important to be able to set the timeout slightly
> longer than the expected duration of each operation to optimise the
> responsiveness of the application. As the instrument may be shared by
> multiple applications the timeout should be settable on a per file
> descriptor basis.
> 
> Tested-by: Dave Penkler <dpenkler@gmail.com>
> Reviewed-by: Steve Bayless <steve_bayless@keysight.com>
> Signed-off-by: Dave Penkler <dpenkler@gmail.com>
> Signed-off-by: Guido Kiener <guido.kiener@rohde-schwarz.com>
> ---
>  drivers/usb/class/usbtmc.c   | 58 +++++++++++++++++++++++++++++++++---
>  include/uapi/linux/usb/tmc.h |  2 ++
>  2 files changed, 56 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
> index 5754354429d8..ad7872003420 100644
> --- a/drivers/usb/class/usbtmc.c
> +++ b/drivers/usb/class/usbtmc.c
> @@ -30,6 +30,8 @@
>   */
>  #define USBTMC_SIZE_IOBUFFER	2048
>  
> +/* Minimum USB timeout (in milliseconds) */
> +#define USBTMC_MIN_TIMEOUT	100
>  /* Default USB timeout (in milliseconds) */
>  #define USBTMC_TIMEOUT		5000
>  
> @@ -116,6 +118,7 @@ struct usbtmc_file_data {
>  	struct usbtmc_device_data *data;
>  	struct list_head file_elem;
>  
> +	u32            timeout;
>  	u8             srq_byte;
>  	atomic_t       srq_asserted;
>  
> @@ -163,6 +166,7 @@ static int usbtmc_open(struct inode *inode, struct file *filp)
>  	file_data->data = data;
>  
>  	/* copy default values from device settings */
> +	file_data->timeout = USBTMC_TIMEOUT;
>  	file_data->TermChar = data->TermChar;
>  	file_data->TermCharEnabled = data->TermCharEnabled;
>  	file_data->auto_abort = data->auto_abort;
> @@ -478,7 +482,7 @@ static int usbtmc488_ioctl_read_stb(struct usbtmc_file_data *file_data,
>  		rv = wait_event_interruptible_timeout(
>  			data->waitq,
>  			atomic_read(&data->iin_data_valid) != 0,
> -			USBTMC_TIMEOUT);
> +			file_data->timeout);
>  		if (rv < 0) {
>  			dev_dbg(dev, "wait interrupted %d\n", rv);
>  			goto exit;
> @@ -613,7 +617,8 @@ static int send_request_dev_dep_msg_in(struct usbtmc_file_data *file_data,
>  	retval = usb_bulk_msg(data->usb_dev,
>  			      usb_sndbulkpipe(data->usb_dev,
>  					      data->bulk_out),
> -			      buffer, USBTMC_HEADER_SIZE, &actual, USBTMC_TIMEOUT);
> +			      buffer, USBTMC_HEADER_SIZE,
> +			      &actual, file_data->timeout);
>  
>  	/* Store bTag (in case we need to abort) */
>  	data->bTag_last_write = data->bTag;
> @@ -681,7 +686,7 @@ static ssize_t usbtmc_read(struct file *filp, char __user *buf,
>  				      usb_rcvbulkpipe(data->usb_dev,
>  						      data->bulk_in),
>  				      buffer, USBTMC_SIZE_IOBUFFER, &actual,
> -				      USBTMC_TIMEOUT);
> +				      file_data->timeout);
>  
>  		dev_dbg(dev, "usb_bulk_msg: retval(%u), done(%zu), remaining(%zu), actual(%d)\n", retval, done, remaining, actual);
>  
> @@ -854,7 +859,7 @@ static ssize_t usbtmc_write(struct file *filp, const char __user *buf,
>  					      usb_sndbulkpipe(data->usb_dev,
>  							      data->bulk_out),
>  					      buffer, n_bytes,
> -					      &actual, USBTMC_TIMEOUT);
> +					      &actual, file_data->timeout);
>  			if (retval != 0)
>  				break;
>  			n_bytes -= actual;
> @@ -1211,6 +1216,41 @@ static int usbtmc_ioctl_indicator_pulse(struct usbtmc_device_data *data)
>  	return rv;
>  }
>  
> +/*
> + * Get the usb timeout value
> + */
> +static int usbtmc_ioctl_get_timeout(struct usbtmc_file_data *file_data,
> +				void __user *arg)
> +{
> +	__u32 timeout;
> +
> +	timeout = file_data->timeout;
> +
> +	return put_user(timeout, (__u32 __user *)arg);
> +}
> +
> +/*
> + * Set the usb timeout value
> + */
> +static int usbtmc_ioctl_set_timeout(struct usbtmc_file_data *file_data,
> +				void __user *arg)
> +{
> +	__u32 timeout;
> +
> +	if (get_user(timeout, (__u32 __user *)arg))
> +		return -EFAULT;
> +
> +	/* Note that timeout = 0 means
> +	 * MAX_SCHEDULE_TIMEOUT in usb_control_msg
> +	 */
> +	if (timeout < USBTMC_MIN_TIMEOUT)
> +		return -EINVAL;
> +
> +	file_data->timeout = timeout;
> +
> +	return 0;
> +}
> +
>  static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>  {
>  	struct usbtmc_file_data *file_data;
> @@ -1251,6 +1291,16 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>  		retval = usbtmc_ioctl_abort_bulk_in(data);
>  		break;
>  
> +	case USBTMC_IOCTL_GET_TIMEOUT:
> +		retval = usbtmc_ioctl_get_timeout(file_data,
> +						  (void __user *)arg);
> +		break;
> +
> +	case USBTMC_IOCTL_SET_TIMEOUT:
> +		retval = usbtmc_ioctl_set_timeout(file_data,
> +						  (void __user *)arg);
> +		break;
> +
>  	case USBTMC488_IOCTL_GET_CAPS:
>  		retval = copy_to_user((void __user *)arg,
>  				&data->usb488_caps,
> diff --git a/include/uapi/linux/usb/tmc.h b/include/uapi/linux/usb/tmc.h
> index 03f6adc8f35b..d6de192150f4 100644
> --- a/include/uapi/linux/usb/tmc.h
> +++ b/include/uapi/linux/usb/tmc.h
> @@ -46,6 +46,8 @@
>  #define USBTMC_IOCTL_ABORT_BULK_IN	_IO(USBTMC_IOC_NR, 4)
>  #define USBTMC_IOCTL_CLEAR_OUT_HALT	_IO(USBTMC_IOC_NR, 6)
>  #define USBTMC_IOCTL_CLEAR_IN_HALT	_IO(USBTMC_IOC_NR, 7)
> +#define USBTMC_IOCTL_GET_TIMEOUT	_IOR(USBTMC_IOC_NR, 9, unsigned int)
> +#define USBTMC_IOCTL_SET_TIMEOUT	_IOW(USBTMC_IOC_NR, 10, unsigned int)

What is the "size" of unsigned int in 32 vs. 64 bit kernels?  Shouldn't
this be __u32?

thanks,

greg k-h
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