The USBTMC_IOCTL_READ call provides for generic synchronous and
asynchronous reads on bulk IN to implement vendor specific library
routines.
Depending on transfer_size the function submits one or more urbs (up
to 16) each with a size of up to 4kB.
The flag USBTMC_FLAG_IGNORE_TRAILER can be used when the transmission
size is already known. Then the function does not truncate the
transfer_size to a multiple of 4 kB, but does reserve extra space
to receive the final short or zero length packet. Note that the
instrument is allowed to send up to wMaxPacketSize - 1 bytes at the
end of a message to avoid sending a zero length packet.
With flag USBTMC_FLAG_ASYNC the ioctl is non blocking. When no
received data is available, the read function submits as many urbs as
needed to receive transfer_size bytes. However the number of flying
urbs (=4kB) is limited to 16 even with subsequent calls of this ioctl.
Returns -EAGAIN when non blocking and no data is received.
Signals EPOLLIN | EPOLLRDNORM when asynchronous urbs are ready to
be read.
In non blocking mode the usbtmc_message.message pointer may be NULL
and the ioctl just submits urbs to initiate receiving data. However if
data is already available due to a previous non blocking call the ioctl
will return -EINVAL when the message pointer is NULL.
Signed-off-by: Guido Kiener <guido.kie...@rohde-schwarz.com>
Reviewed-by: Steve Bayless <steve_bayl...@keysight.com>
---
drivers/usb/class/usbtmc.c | 369 ++++++++++++++++++++++++++++++++++-
include/uapi/linux/usb/tmc.h | 2 +
2 files changed, 370 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 36a35c66f676..1a06478211ea 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -85,6 +85,9 @@ struct usbtmc_device_data {
u8 bTag_last_write; /* needed for abort */
u8 bTag_last_read; /* needed for abort */
+ /* packet size of IN bulk */
+ u16 wMaxPacketSize;
+
/* data for interrupt in endpoint handling */
u8 bNotify1;
u8 bNotify2;
@@ -140,6 +143,13 @@ struct usbtmc_file_data {
struct semaphore limit_write_sem;
u32 out_transfer_size;
int out_status;
+
+ /* data for generic_read */
+ u32 in_transfer_size;
+ int in_status;
+ int in_urbs_used;
+ struct usb_anchor in_anchor;
+ wait_queue_head_t wait_bulk_in;
};
#ifdef CONFIG_COMPAT
@@ -158,6 +168,7 @@ struct compat_usbtmc_message {
#define USBTMC_IOCTL_CTRL_REQUEST32 _IOWR(USBTMC_IOC_NR, 8, struct
compat_usbtmc_ctrlrequest)
#define USBTMC_IOCTL_WRITE32 _IOWR(USBTMC_IOC_NR, 13, struct
compat_usbtmc_message)
+#define USBTMC_IOCTL_READ32 _IOWR(USBTMC_IOC_NR, 14, struct
compat_usbtmc_message)
#endif
@@ -192,6 +203,8 @@ static int usbtmc_open(struct inode *inode, struct file
*filp)
spin_lock_init(&file_data->err_lock);
sema_init(&file_data->limit_write_sem, MAX_URBS_IN_FLIGHT);
init_usb_anchor(&file_data->submitted);
+ init_usb_anchor(&file_data->in_anchor);
+ init_waitqueue_head(&file_data->wait_bulk_in);
data = usb_get_intfdata(intf);
/* Protect reference to data from file structure until release */
@@ -238,6 +251,9 @@ static int usbtmc_flush(struct file *file, fl_owner_t id)
usbtmc_draw_down(file_data);
spin_lock_irq(&file_data->err_lock);
+ file_data->in_status = 0;
+ file_data->in_transfer_size = 0;
+ file_data->in_urbs_used = 0;
file_data->out_status = 0;
file_data->out_transfer_size = 0;
spin_unlock_irq(&file_data->err_lock);
@@ -701,6 +717,331 @@ static struct urb *usbtmc_create_urb(void)
return urb;
}
+static void usbtmc_read_bulk_cb(struct urb *urb)
+{
+ struct usbtmc_file_data *file_data = urb->context;
+ int status = urb->status;
+ unsigned long flags;
+
+ /* sync/async unlink faults aren't errors */
+ if (status) {
+ if (!(/* status == -ENOENT || */
+ status == -ECONNRESET ||
+ status == -EREMOTEIO || /* Short packet */
+ status == -ESHUTDOWN))
+ dev_err(&file_data->data->intf->dev,
+ "%s - nonzero read bulk status received: %d\n",
+ __func__, status);
+
+ spin_lock_irqsave(&file_data->err_lock, flags);
+ if (!file_data->in_status)
+ file_data->in_status = status;
+ spin_unlock_irqrestore(&file_data->err_lock, flags);
+ }
+
+ spin_lock_irqsave(&file_data->err_lock, flags);
+ file_data->in_transfer_size += urb->actual_length;
+ dev_dbg(&file_data->data->intf->dev,
+ "%s - total size: %u current: %d status: %d\n",
+ __func__, file_data->in_transfer_size,
+ urb->actual_length, status);
+ spin_unlock_irqrestore(&file_data->err_lock, flags);
+ usb_anchor_urb(urb, &file_data->in_anchor);
+
+ wake_up_interruptible(&file_data->wait_bulk_in);
+ wake_up_interruptible(&file_data->data->waitq);
+}
+
+static inline bool usbtmc_do_transfer(struct usbtmc_file_data *file_data)
+{
+ bool data_or_error;
+
+ spin_lock_irq(&file_data->err_lock);
+ data_or_error = !usb_anchor_empty(&file_data->in_anchor)
+ || file_data->in_status;
+ spin_unlock_irq(&file_data->err_lock);
+ dev_dbg(&file_data->data->intf->dev, "%s: returns %d\n", __func__,
+ data_or_error);
+ return data_or_error;
+}
+
+static ssize_t usbtmc_generic_read(struct usbtmc_file_data *file_data,
+ void __user *user_buffer,
+ u32 transfer_size,
+ u32 *transferred,
+ u32 flags)
+{
+ struct usbtmc_device_data *data = file_data->data;
+ struct device *dev = &data->intf->dev;
+ u32 done = 0;
+ u32 remaining;
+ const u32 bufsize = USBTMC_BUFSIZE;
+ int retval = 0;
+ u32 max_transfer_size;
+ unsigned long expire;
+ int bufcount = 1;
+ int again = 0;
+
+ /* mutex already locked */
+
+ *transferred = done;
+
+ max_transfer_size = transfer_size;
+
+ if (flags & USBTMC_FLAG_IGNORE_TRAILER) {
+ /* The device may send extra alignment bytes (up to
+ * wMaxPacketSize – 1) to avoid sending a zero-length
+ * packet
+ */
+ remaining = transfer_size;
+ if ((max_transfer_size % data->wMaxPacketSize) == 0)
+ max_transfer_size += (data->wMaxPacketSize - 1);
+ } else {
+ /* round down to bufsize to avoid truncated data left */
+ if (max_transfer_size > bufsize) {
+ max_transfer_size =
+ roundup(max_transfer_size + 1 - bufsize,
+ bufsize);
+ }
+ remaining = max_transfer_size;
+ }
+
+ spin_lock_irq(&file_data->err_lock);
+
+ if (file_data->in_status) {
+ /* return the very first error */
+ retval = file_data->in_status;
+ spin_unlock_irq(&file_data->err_lock);
+ goto error;
+ }
+
+ if (flags & USBTMC_FLAG_ASYNC) {
+ if (usb_anchor_empty(&file_data->in_anchor))
+ again = 1;
+
+ if (file_data->in_urbs_used == 0) {
+ file_data->in_transfer_size = 0;
+ file_data->in_status = 0;
+ }
+ } else {
+ file_data->in_transfer_size = 0;
+ file_data->in_status = 0;
+ }
+
+ if (max_transfer_size == 0) {
+ bufcount = 0;
+ } else {
+ bufcount = roundup(max_transfer_size, bufsize) / bufsize;
+ if (bufcount > file_data->in_urbs_used)
+ bufcount -= file_data->in_urbs_used;
+ else
+ bufcount = 0;
+
+ if (bufcount + file_data->in_urbs_used > MAX_URBS_IN_FLIGHT) {
+ bufcount = MAX_URBS_IN_FLIGHT -
+ file_data->in_urbs_used;
+ }
+ }
+ spin_unlock_irq(&file_data->err_lock);
+
+ dev_dbg(dev, "%s: requested=%u flags=0x%X size=%u bufs=%d used=%d\n",
+ __func__, transfer_size, flags,
+ max_transfer_size, bufcount, file_data->in_urbs_used);
+
+ while (bufcount > 0) {
+ u8 *dmabuf = NULL;
+ struct urb *urb = usbtmc_create_urb();
+
+ if (!urb) {
+ retval = -ENOMEM;
+ goto error;
+ }
+
+ dmabuf = urb->transfer_buffer;
+
+ usb_fill_bulk_urb(urb, data->usb_dev,
+ usb_rcvbulkpipe(data->usb_dev, data->bulk_in),
+ dmabuf, bufsize,
+ usbtmc_read_bulk_cb, file_data);
+
+ usb_anchor_urb(urb, &file_data->submitted);
+ retval = usb_submit_urb(urb, GFP_KERNEL);
+ /* urb is anchored. We can release our reference. */
+ usb_free_urb(urb);
+ if (unlikely(retval)) {
+ usb_unanchor_urb(urb);
+ goto error;
+ }
+ file_data->in_urbs_used++;
+ bufcount--;
+ }
+
+ if (again) {
+ dev_dbg(dev, "%s: ret=again\n", __func__);
+ return -EAGAIN;
+ }
+
+ if (user_buffer == NULL)
+ return -EINVAL;
+
+ expire = msecs_to_jiffies(file_data->timeout);
+
+ while (max_transfer_size > 0) {
+ u32 this_part;
+ struct urb *urb = NULL;
+
+ if (!(flags & USBTMC_FLAG_ASYNC)) {
+ dev_dbg(dev, "%s: before wait time %lu\n",
+ __func__, expire);
+ retval = wait_event_interruptible_timeout(
+ file_data->wait_bulk_in,
+ usbtmc_do_transfer(file_data),
+ expire);
+
+ dev_dbg(dev, "%s: wait returned %d\n",
+ __func__, retval);
+
+ if (retval <= 0) {
+ if (retval == 0)
+ retval = -ETIMEDOUT;
+ goto error;
+ }
+ }
+
+ urb = usb_get_from_anchor(&file_data->in_anchor);
+ if (!urb) {
+ if (!(flags & USBTMC_FLAG_ASYNC)) {
+ /* synchronous case: must not happen */
+ retval = -EFAULT;
+ goto error;
+ }
+
+ /* asynchronous case: ready, do not block or wait */
+ *transferred = done;
+ dev_dbg(dev, "%s: (async) done=%u ret=0\n",
+ __func__, done);
+ return 0;
+ }
+
+ file_data->in_urbs_used--;
+
+ if (max_transfer_size > urb->actual_length)
+ max_transfer_size -= urb->actual_length;
+ else
+ max_transfer_size = 0;
+
+ if (remaining > urb->actual_length)
+ this_part = urb->actual_length;
+ else
+ this_part = remaining;
+
+ print_hex_dump_debug("usbtmc ", DUMP_PREFIX_NONE, 16, 1,
+ urb->transfer_buffer, urb->actual_length, true);
+
+ if (copy_to_user(user_buffer + done,
+ urb->transfer_buffer, this_part)) {
+ usb_free_urb(urb);
+ retval = -EFAULT;
+ goto error;
+ }
+
+ remaining -= this_part;
+ done += this_part;
+
+ spin_lock_irq(&file_data->err_lock);
+ if (urb->status) {
+ /* return the very first error */
+ retval = file_data->in_status;
+ spin_unlock_irq(&file_data->err_lock);
+ usb_free_urb(urb);
+ goto error;
+ }
+ spin_unlock_irq(&file_data->err_lock);
+
+ if (urb->actual_length < bufsize) {
+ /* short packet or ZLP received => ready */
+ usb_free_urb(urb);
+ retval = 1;
+ break;
+ }
+
+ if (!(flags & USBTMC_FLAG_ASYNC) &&
+ max_transfer_size > (bufsize * file_data->in_urbs_used)) {
+ /* resubmit, since other buffers still not enough */
+ usb_anchor_urb(urb, &file_data->submitted);
+ retval = usb_submit_urb(urb, GFP_KERNEL);
+ if (unlikely(retval)) {
+ usb_unanchor_urb(urb);
+ usb_free_urb(urb);
+ goto error;
+ }
+ file_data->in_urbs_used++;
+ }
+ usb_free_urb(urb);
+ retval = 0;
+ }
+
+error:
+ *transferred = done;
+
+ dev_dbg(dev, "%s: before kill\n", __func__);
+ /* Attention: killing urbs can take long time (2 ms) */
+ usb_kill_anchored_urbs(&file_data->submitted);
+ dev_dbg(dev, "%s: after kill\n", __func__);
+ usb_scuttle_anchored_urbs(&file_data->in_anchor);
+ file_data->in_urbs_used = 0;
+ file_data->in_status = 0; /* no spinlock needed here */
+ dev_dbg(dev, "%s: done=%u ret=%d\n", __func__, done, retval);
+
+ return retval;
+}
+
+static ssize_t usbtmc_ioctl_generic_read(struct usbtmc_file_data *file_data,
+ void __user *arg)
+{
+ struct usbtmc_message msg;
+ ssize_t retval = 0;
+
+ /* mutex already locked */
+
+ if (copy_from_user(&msg, arg, sizeof(struct usbtmc_message)))
+ return -EFAULT;
+
+ retval = usbtmc_generic_read(file_data, msg.message,
+ msg.transfer_size, &msg.transferred,
+ msg.flags);
+
+ if (put_user(msg.transferred,
+ &((struct usbtmc_message __user *)arg)->transferred))
+ return -EFAULT;
+
+ return retval;
+}
+
+#ifdef CONFIG_COMPAT
+static ssize_t usbtmc_ioctl_generic_read32(struct usbtmc_file_data *file_data,
+ void __user *arg)
+{
+ struct compat_usbtmc_message msg;
+ compat_ssize_t retval = 0;
+
+ /* mutex already locked */
+
+ if (copy_from_user(&msg, arg, sizeof(struct compat_usbtmc_message)))
+ return -EFAULT;
+
+ retval = usbtmc_generic_read(file_data, compat_ptr(msg.message),
+ msg.transfer_size, &msg.transferred,
+ msg.flags);
+
+ if (put_user(msg.transferred,
+ &((struct compat_usbtmc_message __user *)arg)->transferred))
+ return -EFAULT;
+
+ return retval;
+}
+#endif
+
static void usbtmc_write_bulk_cb(struct urb *urb)
{
struct usbtmc_file_data *file_data = urb->context;
@@ -1426,6 +1767,7 @@ static int usbtmc_ioctl_clear_in_halt(struct
usbtmc_device_data *data)
static int usbtmc_ioctl_cancel_io(struct usbtmc_file_data *file_data)
{
spin_lock_irq(&file_data->err_lock);
+ file_data->in_status = -ECANCELED;
file_data->out_status = -ECANCELED;
spin_unlock_irq(&file_data->err_lock);
usb_kill_anchored_urbs(&file_data->submitted);
@@ -1884,6 +2226,18 @@ static long usbtmc_ioctl(struct file *file, unsigned int
cmd, unsigned long arg)
break;
#endif
+ case USBTMC_IOCTL_READ:
+ retval = usbtmc_ioctl_generic_read(file_data,
+ (void __user *)arg);
+ break;
+
+#ifdef CONFIG_COMPAT
+ case USBTMC_IOCTL_READ32:
+ retval = usbtmc_ioctl_generic_read32(file_data,
+ (void __user *)arg);
+ break;
+#endif
+
case USBTMC_IOCTL_WRITE_RESULT:
retval = usbtmc_ioctl_write_result(file_data,
(void __user *)arg);
@@ -1934,6 +2288,7 @@ static long usbtmc_compat_ioctl(struct file *file,
unsigned int cmd,
switch (cmd) {
case USBTMC_IOCTL_CTRL_REQUEST:
case USBTMC_IOCTL_WRITE:
+ case USBTMC_IOCTL_READ:
return -EBADRQC;
}
@@ -1963,15 +2318,24 @@ static __poll_t usbtmc_poll(struct file *file,
poll_table *wait)
poll_wait(file, &data->waitq, wait);
+ /* Note that EPOLLPRI is now assigned to SRQ, and
+ * EPOLLIN|EPOLLRDNORM to normal read data.
+ */
mask = 0;
if (atomic_read(&file_data->srq_asserted))
mask |= EPOLLPRI;
+ /* Note that the anchor submitted includes all urbs for BULK IN
+ * and OUT. So EPOLLOUT is signaled when BULK OUT is empty and
+ * all BULK IN urbs are completed and moved to in_anchor.
+ */
if (usb_anchor_empty(&file_data->submitted))
mask |= (EPOLLOUT | EPOLLWRNORM);
+ if (!usb_anchor_empty(&file_data->in_anchor))
+ mask |= (EPOLLIN | EPOLLRDNORM);
spin_lock_irq(&file_data->err_lock);
- if (file_data->out_status)
+ if (file_data->in_status || file_data->out_status)
mask |= EPOLLERR;
spin_unlock_irq(&file_data->err_lock);
@@ -2133,6 +2497,7 @@ static int usbtmc_probe(struct usb_interface *intf,
}
data->bulk_in = bulk_in->bEndpointAddress;
+ data->wMaxPacketSize = usb_endpoint_maxp(bulk_in);
dev_dbg(&intf->dev, "Found bulk in endpoint at %u\n", data->bulk_in);
data->bulk_out = bulk_out->bEndpointAddress;
@@ -2229,6 +2594,7 @@ static void usbtmc_disconnect(struct usb_interface *intf)
struct usbtmc_file_data,
file_elem);
usb_kill_anchored_urbs(&file_data->submitted);
+ usb_scuttle_anchored_urbs(&file_data->in_anchor);
}
mutex_unlock(&data->io_mutex);
usbtmc_free_int(data);
@@ -2242,6 +2608,7 @@ static void usbtmc_draw_down(struct usbtmc_file_data
*file_data)
time = usb_wait_anchor_empty_timeout(&file_data->submitted, 1000);
if (!time)
usb_kill_anchored_urbs(&file_data->submitted);
+ usb_scuttle_anchored_urbs(&file_data->in_anchor);
}
static int usbtmc_suspend(struct usb_interface *intf, pm_message_t message)
diff --git a/include/uapi/linux/usb/tmc.h b/include/uapi/linux/usb/tmc.h
index dc9dd55fa16f..6a947e495865 100644
--- a/include/uapi/linux/usb/tmc.h
+++ b/include/uapi/linux/usb/tmc.h
@@ -64,6 +64,7 @@ struct usbtmc_termchar {
*/
#define USBTMC_FLAG_ASYNC 0x0001
#define USBTMC_FLAG_APPEND 0x0002
+#define USBTMC_FLAG_IGNORE_TRAILER 0x0004
struct usbtmc_message {
__u32 transfer_size; /* size of bytes to transfer */
@@ -86,6 +87,7 @@ struct usbtmc_message {
#define USBTMC_IOCTL_EOM_ENABLE _IOW(USBTMC_IOC_NR, 11, __u8)
#define USBTMC_IOCTL_CONFIG_TERMCHAR _IOW(USBTMC_IOC_NR, 12, struct
usbtmc_termchar)
#define USBTMC_IOCTL_WRITE _IOWR(USBTMC_IOC_NR, 13, struct
usbtmc_message)
+#define USBTMC_IOCTL_READ _IOWR(USBTMC_IOC_NR, 14, struct
usbtmc_message)
#define USBTMC_IOCTL_WRITE_RESULT _IOWR(USBTMC_IOC_NR, 15, __u32)
#define USBTMC488_IOCTL_GET_CAPS _IOR(USBTMC_IOC_NR, 17, unsigned char)
--
2.17.1
--
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