[PATCH v5 2/2] char: xillybus: Add driver for XillyUSB (Xillybus variant for USB)

eli.billauer
2021-05-26T10:04:38Z

The XillyUSB driver is the USB variant for the Xillybus FPGA IP core.
Even though it presents a nearly identical API on the FPGA and host,
it's almost a complete rewrite of the driver: The framework for exchanging
data on a USB bus is fundamentally different from doing the same with a
PCIe interface, which leaves very little in common between the existing
driver and the new one for XillyUSB.

Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
---

Notes:
Changelog:

v5:
- Move xillyusb.c back from staging to char/xillybus/
- Turn previously lockless FIFO into one relying on a lock
- Set driver's soft_unbind flag, so that the device is notified when the
driver is unloaded + due changes for killing URBs as required
- Some refactoring of locks for better granularity
- Avoid using pr_err and pr_warn, replace with dev_* counterparts
- Bump MODULE_VERSION to 1.1
- Remove module_params
- Fix a few minor bugs regarding error handling flow
- Various coding style fixes and comment clarifications

v4:
(No changes)

v3:
- Move to staging
- Rely on xillybus_class for device file operations
- Fix no return value bug in xillyusb_discovery()
- Add module parameters for URB buffer size and count

v2:
- Add comment in Kconfig file, saying XILLYUSB really doesn't depend
on XILLYBUS (following comment by Randy Dunlap)
- Use SEEK_* predefined constants instead of numbers

drivers/char/xillybus/Kconfig | 14 +
drivers/char/xillybus/Makefile | 1 +
drivers/char/xillybus/xillyusb.c | 2260 ++++++++++++++++++++++++++++++
3 files changed, 2275 insertions(+)
create mode 100644 drivers/char/xillybus/xillyusb.c

diff --git a/drivers/char/xillybus/Kconfig b/drivers/char/xillybus/Kconfig
index 7cc4d719ec4f..a8036dad437e 100644
--- a/drivers/char/xillybus/Kconfig
+++ b/drivers/char/xillybus/Kconfig
@@ -36,3 +36,17 @@ config XILLYBUS_OF
system, say M. The module will be called xillybus_of.

endif # if XILLYBUS
+
+# XILLYUSB doesn't depend on XILLYBUS
+
+config XILLYUSB
+ tristate "XillyUSB: Xillybus generic FPGA interface for USB"
+ depends on USB
+ select CRC32
+ select XILLYBUS_CLASS
+ help
+ XillyUSB is the Xillybus variant which uses USB for communicating
+ with the FPGA.
+
+ Set to M if you want Xillybus to use USB for communicating with
+ the FPGA. The module will be called xillyusb.
diff --git a/drivers/char/xillybus/Makefile b/drivers/char/xillybus/Makefile
index 591615264591..16f31d03209d 100644
--- a/drivers/char/xillybus/Makefile
+++ b/drivers/char/xillybus/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_XILLYBUS_CLASS) += xillybus_class.o
obj-$(CONFIG_XILLYBUS) += xillybus_core.o
obj-$(CONFIG_XILLYBUS_PCIE) += xillybus_pcie.o
obj-$(CONFIG_XILLYBUS_OF) += xillybus_of.o
+obj-$(CONFIG_XILLYUSB) += xillyusb.o
diff --git a/drivers/char/xillybus/xillyusb.c b/drivers/char/xillybus/xillyusb.c
new file mode 100644
index 000000000000..1e15706af749
--- /dev/null
+++ b/drivers/char/xillybus/xillyusb.c
@@ -0,0 +1,2260 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2020 Xillybus Ltd, http://xillybus.com
+ *
+ * Driver for the XillyUSB FPGA/host framework.
+ *
+ * This driver interfaces with a special IP core in an FPGA, setting up
+ * a pipe between a hardware FIFO in the programmable logic and a device
+ * file in the host. The number of such pipes and their attributes are
+ * set up on the logic. This driver detects these automatically and
+ * creates the device files accordingly.
+ */
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <asm/byteorder.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+#include <linux/crc32.h>
+#include <linux/poll.h>
+#include <linux/delay.h>
+#include <linux/usb.h>
+
+#include "xillybus_class.h"
+
+MODULE_DESCRIPTION("Driver for XillyUSB FPGA IP Core");
+MODULE_AUTHOR("Eli Billauer, Xillybus Ltd.");
+MODULE_VERSION("1.1");
+MODULE_ALIAS("xillyusb");
+MODULE_LICENSE("GPL v2");
+
+#define XILLY_RX_TIMEOUT (10 * HZ / 1000)
+#define XILLY_RESPONSE_TIMEOUT (500 * HZ / 1000)
+
+#define BUF_SIZE_ORDER 4
+#define BUFNUM 8
+#define LOG2_IDT_FIFO_SIZE 16
+#define LOG2_INITIAL_FIFO_BUF_SIZE 16
+
+#define MSG_EP_NUM 1
+#define IN_EP_NUM 1
+
+static const char xillyname[] = "xillyusb";
+
+static unsigned int fifo_buf_order;
+
+#define USB_VENDOR_ID_XILINX 0x03fd
+#define USB_VENDOR_ID_ALTERA 0x09fb
+
+#define USB_PRODUCT_ID_XILLYUSB 0xebbe
+
+static const struct usb_device_id xillyusb_table[] = {
+ { USB_DEVICE(USB_VENDOR_ID_XILINX, USB_PRODUCT_ID_XILLYUSB) },
+ { USB_DEVICE(USB_VENDOR_ID_ALTERA, USB_PRODUCT_ID_XILLYUSB) },
+ { }
+};
+
+MODULE_DEVICE_TABLE(usb, xillyusb_table);
+
+struct xillyusb_dev;
+
+struct xillyfifo {
+ unsigned int bufsize; /* In bytes, always a power of 2 */
+ unsigned int bufnum;
+ unsigned int size; /* Lazy: Equals bufsize * bufnum */
+ unsigned int buf_order;
+
+ int fill; /* Number of bytes in the FIFO */
+ spinlock_t lock;
+ wait_queue_head_t waitq;
+
+ unsigned int readpos;
+ unsigned int readbuf;
+ unsigned int writepos;
+ unsigned int writebuf;
+ char **mem;
+};
+
+struct xillyusb_channel;
+
+struct xillyusb_endpoint {
+ struct xillyusb_dev *xdev;
+
+ struct mutex ep_mutex; /* serialize operations on endpoint */
+
+ struct list_head buffers;
+ struct list_head filled_buffers;
+ spinlock_t buffers_lock; /* protect these two lists */
+
+ unsigned int order;
+ unsigned int buffer_size;
+
+ unsigned int fill_mask;
+
+ int outstanding_urbs;
+
+ struct usb_anchor anchor;
+
+ struct xillyfifo fifo;
+
+ struct work_struct workitem;
+
+ bool shutting_down;
+ bool drained;
+ bool wake_on_drain;
+
+ u8 ep_num;
+};
+
+struct xillyusb_channel {
+ struct xillyusb_dev *xdev;
+
+ struct xillyfifo *in_fifo;
+ struct xillyusb_endpoint *out_ep;
+ struct mutex lock; /* protect @out_ep, @in_fifo, bit fields below */
+
+ struct mutex in_mutex; /* serialize fops on FPGA to host stream */
+ struct mutex out_mutex; /* serialize fops on host to FPGA stream */
+ wait_queue_head_t flushq;
+
+ int chan_idx;
+
+ u32 in_consumed_bytes;
+ u32 in_current_checkpoint;
+ u32 out_bytes;
+
+ unsigned int in_log2_element_size;
+ unsigned int out_log2_element_size;
+ unsigned int in_log2_fifo_size;
+ unsigned int out_log2_fifo_size;
+
+ unsigned int read_data_ok; /* EOF not arrived (yet) */
+ unsigned int poll_used;
+ unsigned int flushing;
+ unsigned int flushed;
+ unsigned int canceled;
+
+ /* Bit fields protected by @lock except for initialization */
+ unsigned readable:1;
+ unsigned writable:1;
+ unsigned open_for_read:1;
+ unsigned open_for_write:1;
+ unsigned in_synchronous:1;
+ unsigned out_synchronous:1;
+ unsigned in_seekable:1;
+ unsigned out_seekable:1;
+};
+
+struct xillybuffer {
+ struct list_head entry;
+ struct xillyusb_endpoint *ep;
+ void *buf;
+ unsigned int len;
+};
+
+struct xillyusb_dev {
+ struct xillyusb_channel *channels;
+
+ struct usb_device *udev;
+ struct device *dev; /* For dev_err() and such */
+ struct kref kref;
+ struct workqueue_struct *workq;
+
+ int error;
+ spinlock_t error_lock; /* protect @error */
+ struct work_struct wakeup_workitem;
+
+ int num_channels;
+
+ struct xillyusb_endpoint *msg_ep;
+ struct xillyusb_endpoint *in_ep;
+
+ struct mutex msg_mutex; /* serialize opcode transmission */
+ int in_bytes_left;
+ int leftover_chan_num;
+ unsigned int in_counter;
+ struct mutex process_in_mutex; /* synchronize wakeup_all() */
+};
+
+/* FPGA to host opcodes */
+enum {
+ OPCODE_DATA = 0,
+ OPCODE_QUIESCE_ACK = 1,
+ OPCODE_EOF = 2,
+ OPCODE_REACHED_CHECKPOINT = 3,
+ OPCODE_CANCELED_CHECKPOINT = 4,
+};
+
+/* Host to FPGA opcodes */
+enum {
+ OPCODE_QUIESCE = 0,
+ OPCODE_REQ_IDT = 1,
+ OPCODE_SET_CHECKPOINT = 2,
+ OPCODE_CLOSE = 3,
+ OPCODE_SET_PUSH = 4,
+ OPCODE_UPDATE_PUSH = 5,
+ OPCODE_CANCEL_CHECKPOINT = 6,
+ OPCODE_SET_ADDR = 7,
+};
+
+/*
+ * fifo_write() and fifo_read() are NOT reentrant (i.e. concurrent multiple
+ * calls to each on the same FIFO is not allowed) however it's OK to have
+ * threads calling each of the two functions once on the same FIFO, and
+ * at the same time.
+ */
+
+static int fifo_write(struct xillyfifo *fifo,
+ const void *data, unsigned int len,
+ int (*copier)(void *, const void *, int))
+{
+ unsigned int done = 0;
+ unsigned int todo = len;
+ unsigned int nmax;
+ unsigned int writepos = fifo->writepos;
+ unsigned int writebuf = fifo->writebuf;
+ unsigned long flags;
+ int rc;
+
+ nmax = fifo->size - READ_ONCE(fifo->fill);
+
+ while (1) {
+ unsigned int nrail = fifo->bufsize - writepos;
+ unsigned int n = min(todo, nmax);
+
+ if (n == 0) {
+ spin_lock_irqsave(&fifo->lock, flags);
+ fifo->fill += done;
+ spin_unlock_irqrestore(&fifo->lock, flags);
+
+ fifo->writepos = writepos;
+ fifo->writebuf = writebuf;
+
+ return done;
+ }
+
+ if (n > nrail)
+ n = nrail;
+
+ rc = (*copier)(fifo->mem[writebuf] + writepos, data + done, n);
+
+ if (rc)
+ return rc;
+
+ done += n;
+ todo -= n;
+
+ writepos += n;
+ nmax -= n;
+
+ if (writepos == fifo->bufsize) {
+ writepos = 0;
+ writebuf++;
+
+ if (writebuf == fifo->bufnum)
+ writebuf = 0;
+ }
+ }
+}
+
+static int fifo_read(struct xillyfifo *fifo,
+ void *data, unsigned int len,
+ int (*copier)(void *, const void *, int))
+{
+ unsigned int done = 0;
+ unsigned int todo = len;
+ unsigned int fill;
+ unsigned int readpos = fifo->readpos;
+ unsigned int readbuf = fifo->readbuf;
+ unsigned long flags;
+ int rc;
+
+ /*
+ * The spinlock here is necessary, because otherwise fifo->fill
+ * could have been increased by fifo_write() after writing data
+ * to the buffer, but this data would potentially not have been
+ * visible on this thread at the time the updated fifo->fill was.
+ * That could lead to reading invalid data.
+ */
+
+ spin_lock_irqsave(&fifo->lock, flags);
+ fill = fifo->fill;
+ spin_unlock_irqrestore(&fifo->lock, flags);
+
+ while (1) {
+ unsigned int nrail = fifo->bufsize - readpos;
+ unsigned int n = min(todo, fill);
+
+ if (n == 0) {
+ spin_lock_irqsave(&fifo->lock, flags);
+ fifo->fill -= done;
+ spin_unlock_irqrestore(&fifo->lock, flags);
+
+ fifo->readpos = readpos;
+ fifo->readbuf = readbuf;
+
+ return done;
+ }
+
+ if (n > nrail)
+ n = nrail;
+
+ rc = (*copier)(data + done, fifo->mem[readbuf] + readpos, n);
+
+ if (rc)
+ return rc;
+
+ done += n;
+ todo -= n;
+
+ readpos += n;
+ fill -= n;
+
+ if (readpos == fifo->bufsize) {
+ readpos = 0;
+ readbuf++;
+
+ if (readbuf == fifo->bufnum)
+ readbuf = 0;
+ }
+ }
+}
+
+/*
+ * These three wrapper functions are used as the @copier argument to
+ * fifo_write() and fifo_read(), so that they can work directly with
+ * user memory as well.
+ */
+
+static int xilly_copy_from_user(void *dst, const void *src, int n)
+{
+ if (copy_from_user(dst, (const void __user *)src, n))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int xilly_copy_to_user(void *dst, const void *src, int n)
+{
+ if (copy_to_user((void __user *)dst, src, n))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int xilly_memcpy(void *dst, const void *src, int n)
+{
+ memcpy(dst, src, n);
+
+ return 0;
+}
+
+static int fifo_init(struct xillyfifo *fifo,
+ unsigned int log2_size)
+{
+ unsigned int log2_bufnum;
+ unsigned int buf_order;
+ int i;
+
+ unsigned int log2_fifo_buf_size;
+
+retry:
+ log2_fifo_buf_size = fifo_buf_order + PAGE_SHIFT;
+
+ if (log2_size > log2_fifo_buf_size) {
+ log2_bufnum = log2_size - log2_fifo_buf_size;
+ buf_order = fifo_buf_order;
+ fifo->bufsize = 1 << log2_fifo_buf_size;
+ } else {
+ log2_bufnum = 0;
+ buf_order = (log2_size > PAGE_SHIFT) ?
+ log2_size - PAGE_SHIFT : 0;
+ fifo->bufsize = 1 << log2_size;
+ }
+
+ fifo->bufnum = 1 << log2_bufnum;
+ fifo->size = fifo->bufnum * fifo->bufsize;
+ fifo->buf_order = buf_order;
+
+ fifo->mem = kmalloc_array(fifo->bufnum, sizeof(void *), GFP_KERNEL);
+
+ if (!fifo->mem)
+ return -ENOMEM;
+
+ for (i = 0; i < fifo->bufnum; i++) {
+ fifo->mem[i] = (void *)
+ __get_free_pages(GFP_KERNEL, buf_order);
+
+ if (!fifo->mem[i])
+ goto memfail;
+ }
+
+ fifo->fill = 0;
+ fifo->readpos = 0;
+ fifo->readbuf = 0;
+ fifo->writepos = 0;
+ fifo->writebuf = 0;
+ spin_lock_init(&fifo->lock);
+ init_waitqueue_head(&fifo->waitq);
+ return 0;
+
+memfail:
+ for (i--; i >= 0; i--)
+ free_pages((unsigned long)fifo->mem[i], buf_order);
+
+ kfree(fifo->mem);
+ fifo->mem = NULL;
+
+ if (fifo_buf_order) {
+ fifo_buf_order--;
+ goto retry;
+ } else {
+ return -ENOMEM;
+ }
+}
+
+static void fifo_mem_release(struct xillyfifo *fifo)
+{
+ int i;
+
+ if (!fifo->mem)
+ return;
+
+ for (i = 0; i < fifo->bufnum; i++)
+ free_pages((unsigned long)fifo->mem[i], fifo->buf_order);
+
+ kfree(fifo->mem);
+}
+
+/*
+ * When endpoint_quiesce() returns, the endpoint has no URBs submitted,
+ * won't accept any new URB submissions, and its related work item doesn't
+ * and won't run anymore.
+ */
+
+static void endpoint_quiesce(struct xillyusb_endpoint *ep)
+{
+ mutex_lock(&ep->ep_mutex);
+ ep->shutting_down = true;
+ mutex_unlock(&ep->ep_mutex);
+
+ usb_kill_anchored_urbs(&ep->anchor);
+ cancel_work_sync(&ep->workitem);
+}
+
+/*
+ * Note that endpoint_dealloc() also frees fifo memory (if allocated), even
+ * though endpoint_alloc doesn't allocate that memory.
+ */
+
+static void endpoint_dealloc(struct xillyusb_endpoint *ep)
+{
+ struct list_head *this, *next;
+
+ fifo_mem_release(&ep->fifo);
+
+ /* Join @filled_buffers with @buffers to free these entries too */
+ list_splice(&ep->filled_buffers, &ep->buffers);
+
+ list_for_each_safe(this, next, &ep->buffers) {
+ struct xillybuffer *xb =
+ list_entry(this, struct xillybuffer, entry);
+
+ free_pages((unsigned long)xb->buf, ep->order);
+ kfree(xb);
+ }
+
+ kfree(ep);
+}
+
+static struct xillyusb_endpoint
+*endpoint_alloc(struct xillyusb_dev *xdev,
+ u8 ep_num,
+ void (*work)(struct work_struct *),
+ unsigned int order,
+ int bufnum)
+{
+ int i;
+
+ struct xillyusb_endpoint *ep;
+
+ ep = kzalloc(sizeof(*ep), GFP_KERNEL);
+
+ if (!ep)
+ return NULL;
+
+ INIT_LIST_HEAD(&ep->buffers);
+ INIT_LIST_HEAD(&ep->filled_buffers);
+
+ spin_lock_init(&ep->buffers_lock);
+ mutex_init(&ep->ep_mutex);
+
+ init_usb_anchor(&ep->anchor);
+ INIT_WORK(&ep->workitem, work);
+
+ ep->order = order;
+ ep->buffer_size = 1 << (PAGE_SHIFT + order);
+ ep->outstanding_urbs = 0;
+ ep->drained = true;
+ ep->wake_on_drain = false;
+ ep->xdev = xdev;
+ ep->ep_num = ep_num;
+ ep->shutting_down = false;
+
+ for (i = 0; i < bufnum; i++) {
+ struct xillybuffer *xb;
+ unsigned long addr;
+
+ xb = kzalloc(sizeof(*xb), GFP_KERNEL);
+
+ if (!xb) {
+ endpoint_dealloc(ep);
+ return NULL;
+ }
+
+ addr = __get_free_pages(GFP_KERNEL, order);
+
+ if (!addr) {
+ kfree(xb);
+ endpoint_dealloc(ep);
+ return NULL;
+ }
+
+ xb->buf = (void *)addr;
+ xb->ep = ep;
+ list_add_tail(&xb->entry, &ep->buffers);
+ }
+ return ep;
+}
+
+static void cleanup_dev(struct kref *kref)
+{
+ struct xillyusb_dev *xdev =
+ container_of(kref, struct xillyusb_dev, kref);
+
+ if (xdev->in_ep)
+ endpoint_dealloc(xdev->in_ep);
+
+ if (xdev->msg_ep)
+ endpoint_dealloc(xdev->msg_ep);
+
+ if (xdev->workq)
+ destroy_workqueue(xdev->workq);
+
+ kfree(xdev->channels); /* Argument may be NULL, and that's fine */
+ kfree(xdev);
+}
+
+/*
+ * @process_in_mutex is taken to ensure that bulk_in_work() won't call
+ * process_bulk_in() after wakeup_all()'s execution: The latter zeroes all
+ * @read_data_ok entries, which will make process_bulk_in() report false
+ * errors if executed. The mechanism relies on that xdev->error is assigned
+ * a non-zero value by report_io_error() prior to queueing wakeup_all(),
+ * which prevents bulk_in_work() from calling process_bulk_in().
+ *
+ * The fact that wakeup_all() and bulk_in_work() are queued on the same
+ * workqueue makes their concurrent execution very unlikely, however the
+ * kernel's API doesn't seem to ensure this strictly.
+ */
+
+static void wakeup_all(struct work_struct *work)
+{
+ int i;
+ struct xillyusb_dev *xdev = container_of(work, struct xillyusb_dev,
+ wakeup_workitem);
+
+ mutex_lock(&xdev->process_in_mutex);
+
+ for (i = 0; i < xdev->num_channels; i++) {
+ struct xillyusb_channel *chan = &xdev->channels[i];
+
+ mutex_lock(&chan->lock);
+
+ if (chan->in_fifo) {
+ /*
+ * Fake an EOF: Even if such arrives, it won't be
+ * processed.
+ */
+ chan->read_data_ok = 0;
+ wake_up_interruptible(&chan->in_fifo->waitq);
+ }
+
+ if (chan->out_ep)
+ wake_up_interruptible(&chan->out_ep->fifo.waitq);
+
+ mutex_unlock(&chan->lock);
+
+ wake_up_interruptible(&chan->flushq);
+ }
+
+ mutex_unlock(&xdev->process_in_mutex);
+
+ wake_up_interruptible(&xdev->msg_ep->fifo.waitq);
+
+ kref_put(&xdev->kref, cleanup_dev);
+}
+
+static void report_io_error(struct xillyusb_dev *xdev,
+ int errcode)
+{
+ unsigned long flags;
+ bool do_once = false;
+
+ spin_lock_irqsave(&xdev->error_lock, flags);
+ if (!xdev->error) {
+ xdev->error = errcode;
+ do_once = true;
+ }
+ spin_unlock_irqrestore(&xdev->error_lock, flags);
+
+ if (do_once) {
+ kref_get(&xdev->kref); /* xdev is used by work item */
+ queue_work(xdev->workq, &xdev->wakeup_workitem);
+ }
+}
+
+/*
+ * safely_assign_in_fifo() changes the value of chan->in_fifo and ensures
+ * the previous pointer is never used after its return.
+ */
+
+static void safely_assign_in_fifo(struct xillyusb_channel *chan,
+ struct xillyfifo *fifo)
+{
+ mutex_lock(&chan->lock);
+ chan->in_fifo = fifo;
+ mutex_unlock(&chan->lock);
+
+ flush_work(&chan->xdev->in_ep->workitem);
+}
+
+static void bulk_in_completer(struct urb *urb)
+{
+ struct xillybuffer *xb = urb->context;
+ struct xillyusb_endpoint *ep = xb->ep;
+ unsigned long flags;
+
+ if (urb->status) {
+ if (!(urb->status == -ENOENT ||
+ urb->status == -ECONNRESET ||
+ urb->status == -ESHUTDOWN))
+ report_io_error(ep->xdev, -EIO);
+
+ spin_lock_irqsave(&ep->buffers_lock, flags);
+ list_add_tail(&xb->entry, &ep->buffers);
+ ep->outstanding_urbs--;
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+
+ return;
+ }
+
+ xb->len = urb->actual_length;
+
+ spin_lock_irqsave(&ep->buffers_lock, flags);
+ list_add_tail(&xb->entry, &ep->filled_buffers);
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+
+ if (!ep->shutting_down)
+ queue_work(ep->xdev->workq, &ep->workitem);
+}
+
+static void bulk_out_completer(struct urb *urb)
+{
+ struct xillybuffer *xb = urb->context;
+ struct xillyusb_endpoint *ep = xb->ep;
+ unsigned long flags;
+
+ if (urb->status &&
+ (!(urb->status == -ENOENT ||
+ urb->status == -ECONNRESET ||
+ urb->status == -ESHUTDOWN)))
+ report_io_error(ep->xdev, -EIO);
+
+ spin_lock_irqsave(&ep->buffers_lock, flags);
+ list_add_tail(&xb->entry, &ep->buffers);
+ ep->outstanding_urbs--;
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+
+ if (!ep->shutting_down)
+ queue_work(ep->xdev->workq, &ep->workitem);
+}
+
+static void try_queue_bulk_in(struct xillyusb_endpoint *ep)
+{
+ struct xillyusb_dev *xdev = ep->xdev;
+ struct xillybuffer *xb;
+ struct urb *urb;
+
+ int rc;
+ unsigned long flags;
+ unsigned int bufsize = ep->buffer_size;
+
+ mutex_lock(&ep->ep_mutex);
+
+ if (ep->shutting_down || xdev->error)
+ goto done;
+
+ while (1) {
+ spin_lock_irqsave(&ep->buffers_lock, flags);
+
+ if (list_empty(&ep->buffers)) {
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+ goto done;
+ }
+
+ xb = list_first_entry(&ep->buffers, struct xillybuffer, entry);
+ list_del(&xb->entry);
+ ep->outstanding_urbs++;
+
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+
+ urb = usb_alloc_urb(0, GFP_KERNEL);
+ if (!urb) {
+ report_io_error(xdev, -ENOMEM);
+ goto relist;
+ }
+
+ usb_fill_bulk_urb(urb, xdev->udev,
+ usb_rcvbulkpipe(xdev->udev, ep->ep_num),
+ xb->buf, bufsize, bulk_in_completer, xb);
+
+ usb_anchor_urb(urb, &ep->anchor);
+
+ rc = usb_submit_urb(urb, GFP_KERNEL);
+
+ if (rc) {
+ report_io_error(xdev, (rc == -ENOMEM) ? -ENOMEM :
+ -EIO);
+ goto unanchor;
+ }
+
+ usb_free_urb(urb); /* This just decrements reference count */
+ }
+
+unanchor:
+ usb_unanchor_urb(urb);
+ usb_free_urb(urb);
+
+relist:
+ spin_lock_irqsave(&ep->buffers_lock, flags);
+ list_add_tail(&xb->entry, &ep->buffers);
+ ep->outstanding_urbs--;
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+
+done:
+ mutex_unlock(&ep->ep_mutex);
+}
+
+static void try_queue_bulk_out(struct xillyusb_endpoint *ep)
+{
+ struct xillyfifo *fifo = &ep->fifo;
+ struct xillyusb_dev *xdev = ep->xdev;
+ struct xillybuffer *xb;
+ struct urb *urb;
+
+ int rc;
+ unsigned int fill;
+ unsigned long flags;
+ bool do_wake = false;
+
+ mutex_lock(&ep->ep_mutex);
+
+ if (ep->shutting_down || xdev->error)
+ goto done;
+
+ fill = READ_ONCE(fifo->fill) & ep->fill_mask;
+
+ while (1) {
+ int count;
+ unsigned int max_read;
+
+ spin_lock_irqsave(&ep->buffers_lock, flags);
+
+ /*
+ * Race conditions might have the FIFO filled while the
+ * endpoint is marked as drained here. That doesn't matter,
+ * because the sole purpose of @drained is to ensure that
+ * certain data has been sent on the USB channel before
+ * shutting it down. Hence knowing that the FIFO appears
+ * to be empty with no outstanding URBs at some moment
+ * is good enough.
+ */
+
+ if (!fill) {
+ ep->drained = !ep->outstanding_urbs;
+ if (ep->drained && ep->wake_on_drain)
+ do_wake = true;
+
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+ goto done;
+ }
+
+ ep->drained = false;
+
+ if ((fill < ep->buffer_size && ep->outstanding_urbs) ||
+ list_empty(&ep->buffers)) {
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+ goto done;
+ }
+
+ xb = list_first_entry(&ep->buffers, struct xillybuffer, entry);
+ list_del(&xb->entry);
+ ep->outstanding_urbs++;
+
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+
+ max_read = min(fill, ep->buffer_size);
+
+ count = fifo_read(&ep->fifo, xb->buf, max_read, xilly_memcpy);
+
+ /*
+ * xilly_memcpy always returns 0 => fifo_read can't fail =>
+ * count > 0
+ */
+
+ urb = usb_alloc_urb(0, GFP_KERNEL);
+ if (!urb) {
+ report_io_error(xdev, -ENOMEM);
+ goto relist;
+ }
+
+ usb_fill_bulk_urb(urb, xdev->udev,
+ usb_sndbulkpipe(xdev->udev, ep->ep_num),
+ xb->buf, count, bulk_out_completer, xb);
+
+ usb_anchor_urb(urb, &ep->anchor);
+
+ rc = usb_submit_urb(urb, GFP_KERNEL);
+
+ if (rc) {
+ report_io_error(xdev, (rc == -ENOMEM) ? -ENOMEM :
+ -EIO);
+ goto unanchor;
+ }
+
+ usb_free_urb(urb); /* This just decrements reference count */
+
+ fill -= count;
+ do_wake = true;
+ }
+
+unanchor:
+ usb_unanchor_urb(urb);
+ usb_free_urb(urb);
+
+relist:
+ spin_lock_irqsave(&ep->buffers_lock, flags);
+ list_add_tail(&xb->entry, &ep->buffers);
+ ep->outstanding_urbs--;
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+
+done:
+ mutex_unlock(&ep->ep_mutex);
+
+ if (do_wake)
+ wake_up_interruptible(&fifo->waitq);
+}
+
+static void bulk_out_work(struct work_struct *work)
+{
+ struct xillyusb_endpoint *ep = container_of(work,
+ struct xillyusb_endpoint,
+ workitem);
+ try_queue_bulk_out(ep);
+}
+
+static int process_in_opcode(struct xillyusb_dev *xdev,
+ int opcode,
+ int chan_num)
+{
+ struct xillyusb_channel *chan;
+ struct device *dev = xdev->dev;
+ int chan_idx = chan_num >> 1;
+
+ if (chan_idx >= xdev->num_channels) {
+ dev_err(dev, "Received illegal channel ID %d from FPGA\n",
+ chan_num);
+ return -EIO;
+ }
+
+ chan = &xdev->channels[chan_idx];
+
+ switch (opcode) {
+ case OPCODE_EOF:
+ if (!chan->read_data_ok) {
+ dev_err(dev, "Received unexpected EOF for channel %d\n",
+ chan_num);
+ return -EIO;
+ }
+
+ /*
+ * A write memory barrier ensures that the FIFO's fill level
+ * is visible before read_data_ok turns zero, so the data in
+ * the FIFO isn't missed by the consumer.
+ */
+ smp_wmb();
+ WRITE_ONCE(chan->read_data_ok, 0);
+ wake_up_interruptible(&chan->in_fifo->waitq);
+ break;
+
+ case OPCODE_REACHED_CHECKPOINT:
+ chan->flushing = 0;
+ wake_up_interruptible(&chan->flushq);
+ break;
+
+ case OPCODE_CANCELED_CHECKPOINT:
+ chan->canceled = 1;
+ wake_up_interruptible(&chan->flushq);
+ break;
+
+ default:
+ dev_err(dev, "Received illegal opcode %d from FPGA\n",
+ opcode);
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static int process_bulk_in(struct xillybuffer *xb)
+{
+ struct xillyusb_endpoint *ep = xb->ep;
+ struct xillyusb_dev *xdev = ep->xdev;
+ struct device *dev = xdev->dev;
+ int dws = xb->len >> 2;
+ __le32 *p = xb->buf;
+ u32 ctrlword;
+ struct xillyusb_channel *chan;
+ struct xillyfifo *fifo;
+ int chan_num = 0, opcode;
+ int chan_idx;
+ int bytes, count, dwconsume;
+ int in_bytes_left = 0;
+ int rc;
+
+ if ((dws << 2) != xb->len) {
+ dev_err(dev, "Received BULK IN transfer with %d bytes, not a multiple of 4\n",
+ xb->len);
+ return -EIO;
+ }
+
+ if (xdev->in_bytes_left) {
+ bytes = min(xdev->in_bytes_left, dws << 2);
+ in_bytes_left = xdev->in_bytes_left - bytes;
+ chan_num = xdev->leftover_chan_num;
+ goto resume_leftovers;
+ }
+
+ while (dws) {
+ ctrlword = le32_to_cpu(*p++);
+ dws--;
+
+ chan_num = ctrlword & 0xfff;
+ count = (ctrlword >> 12) & 0x3ff;
+ opcode = (ctrlword >> 24) & 0xf;
+
+ if (opcode != OPCODE_DATA) {
+ unsigned int in_counter = xdev->in_counter++ & 0x3ff;
+
+ if (count != in_counter) {
+ dev_err(dev, "Expected opcode counter %d, got %d\n",
+ in_counter, count);
+ return -EIO;
+ }
+
+ rc = process_in_opcode(xdev, opcode, chan_num);
+
+ if (rc)
+ return rc;
+
+ continue;
+ }
+
+ bytes = min(count + 1, dws << 2);
+ in_bytes_left = count + 1 - bytes;
+
+resume_leftovers:
+ chan_idx = chan_num >> 1;
+
+ if (!(chan_num & 1) || chan_idx >= xdev->num_channels ||
+ !xdev->channels[chan_idx].read_data_ok) {
+ dev_err(dev, "Received illegal channel ID %d from FPGA\n",
+ chan_num);
+ return -EIO;
+ }
+ chan = &xdev->channels[chan_idx];
+
+ fifo = chan->in_fifo;
+
+ if (unlikely(!fifo))
+ return -EIO; /* We got really unexpected data */
+
+ if (bytes != fifo_write(fifo, p, bytes, xilly_memcpy)) {
+ dev_err(dev, "Misbehaving FPGA overflew an upstream FIFO!\n");
+ return -EIO;
+ }
+
+ wake_up_interruptible(&fifo->waitq);
+
+ dwconsume = (bytes + 3) >> 2;
+ dws -= dwconsume;
+ p += dwconsume;
+ }
+
+ xdev->in_bytes_left = in_bytes_left;
+ xdev->leftover_chan_num = chan_num;
+ return 0;
+}
+
+static void bulk_in_work(struct work_struct *work)
+{
+ struct xillyusb_endpoint *ep =
+ container_of(work, struct xillyusb_endpoint, workitem);
+ struct xillyusb_dev *xdev = ep->xdev;
+ unsigned long flags;
+ struct xillybuffer *xb;
+ bool consumed = false;
+ int rc = 0;
+
+ mutex_lock(&xdev->process_in_mutex);
+
+ spin_lock_irqsave(&ep->buffers_lock, flags);
+
+ while (1) {
+ if (rc || list_empty(&ep->filled_buffers)) {
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+ mutex_unlock(&xdev->process_in_mutex);
+
+ if (rc)
+ report_io_error(xdev, rc);
+ else if (consumed)
+ try_queue_bulk_in(ep);
+
+ return;
+ }
+
+ xb = list_first_entry(&ep->filled_buffers, struct xillybuffer,
+ entry);
+ list_del(&xb->entry);
+
+ spin_unlock_irqrestore(&ep->buffers_lock, flags);
+
+ consumed = true;
+
+ if (!xdev->error)
+ rc = process_bulk_in(xb);
+
+ spin_lock_irqsave(&ep->buffers_lock, flags);
+ list_add_tail(&xb->entry, &ep->buffers);
+ ep->outstanding_urbs--;
+ }
+}
+
+static int xillyusb_send_opcode(struct xillyusb_dev *xdev,
+ int chan_num, char opcode, u32 data)
+{
+ struct xillyusb_endpoint *ep = xdev->msg_ep;
+ struct xillyfifo *fifo = &ep->fifo;
+ __le32 msg[2];
+
+ int rc = 0;
+
+ msg[0] = cpu_to_le32((chan_num & 0xfff) |
+ ((opcode & 0xf) << 24));
+ msg[1] = cpu_to_le32(data);
+
+ mutex_lock(&xdev->msg_mutex);
+
+ /*
+ * The wait queue is woken with the interruptible variant, so the
+ * wait function matches, however returning because of an interrupt
+ * will mess things up considerably, in particular when the caller is
+ * the release method. And the xdev->error part prevents being stuck
+ * forever in the event of a bizarre hardware bug: Pull the USB plug.
+ */
+
+ while (wait_event_interruptible(fifo->waitq,
+ fifo->fill <= (fifo->size - 8) ||
+ xdev->error))
+ ; /* Empty loop */
+
+ if (xdev->error) {
+ rc = xdev->error;
+ goto unlock_done;
+ }
+
+ fifo_write(fifo, (void *)msg, 8, xilly_memcpy);
+
+ try_queue_bulk_out(ep);
+
+unlock_done:
+ mutex_unlock(&xdev->msg_mutex);
+
+ return rc;
+}
+
+/*
+ * Note that flush_downstream() merely waits for the data to arrive to
+ * the application logic at the FPGA -- unlike PCIe Xillybus' counterpart,
+ * it does nothing to make it happen (and neither is it necessary).
+ *
+ * This function is not reentrant for the same @chan, but this is covered
+ * by the fact that for any given @chan, it's called either by the open,
+ * write, llseek and flush fops methods, which can't run in parallel (and the
+ * write + flush and llseek method handlers are protected with out_mutex).
+ *
+ * chan->flushed is there to avoid multiple flushes at the same position,
+ * in particular as a result of programs that close the file descriptor
+ * e.g. after a dup2() for redirection.
+ */
+
+static int flush_downstream(struct xillyusb_channel *chan,
+ long timeout,
+ bool interruptible)
+{
+ struct xillyusb_dev *xdev = chan->xdev;
+ int chan_num = chan->chan_idx << 1;
+ long deadline, left_to_sleep;
+ int rc;
+
+ if (chan->flushed)
+ return 0;
+
+ deadline = jiffies + 1 + timeout;
+
+ if (chan->flushing) {
+ long cancel_deadline = jiffies + 1 + XILLY_RESPONSE_TIMEOUT;
+
+ chan->canceled = 0;
+ rc = xillyusb_send_opcode(xdev, chan_num,
+ OPCODE_CANCEL_CHECKPOINT, 0);
+
+ if (rc)
+ return rc; /* Only real error, never -EINTR */
+
+ /* Ignoring interrupts. Cancellation must be handled */
+ while (!chan->canceled) {
+ left_to_sleep = cancel_deadline - ((long)jiffies);
+
+ if (left_to_sleep <= 0) {
+ report_io_error(xdev, -EIO);
+ return -EIO;
+ }
+
+ rc = wait_event_interruptible_timeout(chan->flushq,
+ chan->canceled ||
+ xdev->error,
+ left_to_sleep);
+
+ if (xdev->error)
+ return xdev->error;
+ }
+ }
+
+ chan->flushing = 1;
+
+ /*
+ * The checkpoint is given in terms of data elements, not bytes. As
+ * a result, if less than an element's worth of data is stored in the
+ * FIFO, it's not flushed, including the flush before closing, which
+ * means that such data is lost. This is consistent with PCIe Xillybus.
+ */
+
+ rc = xillyusb_send_opcode(xdev, chan_num,
+ OPCODE_SET_CHECKPOINT,
+ chan->out_bytes >>
+ chan->out_log2_element_size);
+
+ if (rc)
+ return rc; /* Only real error, never -EINTR */
+
+ if (!timeout) {
+ while (chan->flushing) {
+ rc = wait_event_interruptible(chan->flushq,
+ !chan->flushing ||
+ xdev->error);
+ if (xdev->error)
+ return xdev->error;
+
+ if (interruptible && rc)
+ return -EINTR;
+ }
+
+ goto done;
+ }
+
+ while (chan->flushing) {
+ left_to_sleep = deadline - ((long)jiffies);
+
+ if (left_to_sleep <= 0)
+ return -ETIMEDOUT;
+
+ rc = wait_event_interruptible_timeout(chan->flushq,
+ !chan->flushing ||
+ xdev->error,
+ left_to_sleep);
+
+ if (xdev->error)
+ return xdev->error;
+
+ if (interruptible && rc < 0)
+ return -EINTR;
+ }
+
+done:
+ chan->flushed = 1;
+ return 0;
+}
+
+/* request_read_anything(): Ask the FPGA for any little amount of data */
+static int request_read_anything(struct xillyusb_channel *chan,
+ char opcode)
+{
+ struct xillyusb_dev *xdev = chan->xdev;
+ unsigned int sh = chan->in_log2_element_size;
+ int chan_num = (chan->chan_idx << 1) | 1;
+ u32 mercy = chan->in_consumed_bytes + (2 << sh) - 1;
+
+ return xillyusb_send_opcode(xdev, chan_num, opcode, mercy >> sh);
+}
+
+static int xillyusb_open(struct inode *inode, struct file *filp)
+{
+ struct xillyusb_dev *xdev;
+ struct xillyusb_channel *chan;
+ struct xillyfifo *in_fifo = NULL;
+ struct xillyusb_endpoint *out_ep = NULL;
+ int rc;
+ int index;
+
+ rc = xillybus_find_inode(inode, (void **)&xdev, &index);
+ if (rc)
+ return rc;
+
+ chan = &xdev->channels[index];
+ filp->private_data = chan;
+
+ mutex_lock(&chan->lock);
+
+ rc = -ENODEV;
+
+ if (xdev->error)
+ goto unmutex_fail;
+
+ if (((filp->f_mode & FMODE_READ) && !chan->readable) ||
+ ((filp->f_mode & FMODE_WRITE) && !chan->writable))
+ goto unmutex_fail;
+
+ if ((filp->f_flags & O_NONBLOCK) && (filp->f_mode & FMODE_READ) &&
+ chan->in_synchronous) {
+ dev_err(xdev->dev,
+ "open() failed: O_NONBLOCK not allowed for read on this device\n");
+ goto unmutex_fail;
+ }
+
+ if ((filp->f_flags & O_NONBLOCK) && (filp->f_mode & FMODE_WRITE) &&
+ chan->out_synchronous) {
+ dev_err(xdev->dev,
+ "open() failed: O_NONBLOCK not allowed for write on this device\n");
+ goto unmutex_fail;
+ }
+
+ rc = -EBUSY;
+
+ if (((filp->f_mode & FMODE_READ) && chan->open_for_read) ||
+ ((filp->f_mode & FMODE_WRITE) && chan->open_for_write))
+ goto unmutex_fail;
+
+ kref_get(&xdev->kref);
+
+ if (filp->f_mode & FMODE_READ)
+ chan->open_for_read = 1;
+
+ if (filp->f_mode & FMODE_WRITE)
+ chan->open_for_write = 1;
+
+ mutex_unlock(&chan->lock);
+
+ if (filp->f_mode & FMODE_WRITE) {
+ out_ep = endpoint_alloc(xdev,
+ (chan->chan_idx + 2) | USB_DIR_OUT,
+ bulk_out_work, BUF_SIZE_ORDER, BUFNUM);
+
+ if (!out_ep) {
+ rc = -ENOMEM;
+ goto unopen;
+ }
+
+ rc = fifo_init(&out_ep->fifo, chan->out_log2_fifo_size);
+
+ if (rc)
+ goto late_unopen;
+
+ out_ep->fill_mask = -(1 << chan->out_log2_element_size);
+ chan->out_bytes = 0;
+ chan->flushed = 0;
+
+ /*
+ * Sending a flush request to a previously closed stream
+ * effectively opens it, and also waits until the command is
+ * confirmed by the FPGA. The latter is necessary because the
+ * data is sent through a separate BULK OUT endpoint, and the
+ * xHCI controller is free to reorder transmissions.
+ *
+ * This can't go wrong unless there's a serious hardware error
+ * (or the computer is stuck for 500 ms?)
+ */
+ rc = flush_downstream(chan, XILLY_RESPONSE_TIMEOUT, false);
+
+ if (rc == -ETIMEDOUT) {
+ rc = -EIO;
+ report_io_error(xdev, rc);
+ }
+
+ if (rc)
+ goto late_unopen;
+ }
+
+ if (filp->f_mode & FMODE_READ) {
+ in_fifo = kzalloc(sizeof(*in_fifo), GFP_KERNEL);
+
+ if (!in_fifo) {
+ rc = -ENOMEM;
+ goto late_unopen;
+ }
+
+ rc = fifo_init(in_fifo, chan->in_log2_fifo_size);
+
+ if (rc) {
+ kfree(in_fifo);
+ goto late_unopen;
+ }
+ }
+
+ mutex_lock(&chan->lock);
+ if (in_fifo) {
+ chan->in_fifo = in_fifo;
+ chan->read_data_ok = 1;
+ }
+ if (out_ep)
+ chan->out_ep = out_ep;
+ mutex_unlock(&chan->lock);
+
+ if (in_fifo) {
+ u32 in_checkpoint = 0;
+
+ if (!chan->in_synchronous)
+ in_checkpoint = in_fifo->size >>
+ chan->in_log2_element_size;
+
+ chan->in_consumed_bytes = 0;
+ chan->poll_used = 0;
+ chan->in_current_checkpoint = in_checkpoint;
+ rc = xillyusb_send_opcode(xdev, (chan->chan_idx << 1) | 1,
+ OPCODE_SET_CHECKPOINT,
+ in_checkpoint);
+
+ if (rc) /* Failure guarantees that opcode wasn't sent */
+ goto unfifo;
+
+ /*
+ * In non-blocking mode, request the FPGA to send any data it
+ * has right away. Otherwise, the first read() will always
+ * return -EAGAIN, which is OK strictly speaking, but ugly.
+ * Checking and unrolling if this fails isn't worth the
+ * effort -- the error is propagated to the first read()
+ * anyhow.
+ */
+ if (filp->f_flags & O_NONBLOCK)
+ request_read_anything(chan, OPCODE_SET_PUSH);
+ }
+
+ return 0;
+
+unfifo:
+ chan->read_data_ok = 0;
+ safely_assign_in_fifo(chan, NULL);
+ fifo_mem_release(in_fifo);
+ kfree(in_fifo);
+
+ if (out_ep) {
+ mutex_lock(&chan->lock);
+ chan->out_ep = NULL;
+ mutex_unlock(&chan->lock);
+ }
+
+late_unopen:
+ if (out_ep)
+ endpoint_dealloc(out_ep);
+
+unopen:
+ mutex_lock(&chan->lock);
+
+ if (filp->f_mode & FMODE_READ)
+ chan->open_for_read = 0;
+
+ if (filp->f_mode & FMODE_WRITE)
+ chan->open_for_write = 0;
+
+ mutex_unlock(&chan->lock);
+
+ kref_put(&xdev->kref, cleanup_dev);
+
+ return rc;
+
+unmutex_fail:
+ mutex_unlock(&chan->lock);
+ return rc;
+}
+
+static ssize_t xillyusb_read(struct file *filp, char __user *userbuf,
+ size_t count, loff_t *f_pos)
+{
+ struct xillyusb_channel *chan = filp->private_data;
+ struct xillyusb_dev *xdev = chan->xdev;
+ struct xillyfifo *fifo = chan->in_fifo;
+ int chan_num = (chan->chan_idx << 1) | 1;
+
+ long deadline, left_to_sleep;
+ int bytes_done = 0;
+ bool sent_set_push = false;
+ int rc;
+
+ deadline = jiffies + 1 + XILLY_RX_TIMEOUT;
+
+ rc = mutex_lock_interruptible(&chan->in_mutex);
+
+ if (rc)
+ return rc;
+
+ while (1) {
+ u32 fifo_checkpoint_bytes, complete_checkpoint_bytes;
+ u32 complete_checkpoint, fifo_checkpoint;
+ u32 checkpoint;
+ s32 diff, leap;
+ unsigned int sh = chan->in_log2_element_size;
+ bool checkpoint_for_complete;
+
+ rc = fifo_read(fifo, (__force void *)userbuf + bytes_done,
+ count - bytes_done, xilly_copy_to_user);
+
+ if (rc < 0)
+ break;
+
+ bytes_done += rc;
+ chan->in_consumed_bytes += rc;
+
+ left_to_sleep = deadline - ((long)jiffies);
+
+ /*
+ * Some 32-bit arithmetic that may wrap. Note that
+ * complete_checkpoint is rounded up to the closest element
+ * boundary, because the read() can't be completed otherwise.
+ * fifo_checkpoint_bytes is rounded down, because it protects
+ * in_fifo from overflowing.
+ */
+
+ fifo_checkpoint_bytes = chan->in_consumed_bytes + fifo->size;
+ complete_checkpoint_bytes =
+ chan->in_consumed_bytes + count - bytes_done;
+
+ fifo_checkpoint = fifo_checkpoint_bytes >> sh;
+ complete_checkpoint =
+ (complete_checkpoint_bytes + (1 << sh) - 1) >> sh;
+
+ diff = (fifo_checkpoint - complete_checkpoint) << sh;
+
+ if (chan->in_synchronous && diff >= 0) {
+ checkpoint = complete_checkpoint;
+ checkpoint_for_complete = true;
+ } else {
+ checkpoint = fifo_checkpoint;
+ checkpoint_for_complete = false;
+ }
+
+ leap = (checkpoint - chan->in_current_checkpoint) << sh;
+
+ /*
+ * To prevent flooding of OPCODE_SET_CHECKPOINT commands as
+ * data is consumed, it's issued only if it moves the
+ * checkpoint by at least an 8th of the FIFO's size, or if
+ * it's necessary to complete the number of bytes requested by
+ * the read() call.
+ *
+ * chan->read_data_ok is checked to spare an unnecessary
+ * submission after receiving EOF, however it's harmless if
+ * such slips away.
+ */
+
+ if (chan->read_data_ok &&
+ (leap > (fifo->size >> 3) ||
+ (checkpoint_for_complete && leap > 0))) {
+ chan->in_current_checkpoint = checkpoint;
+ rc = xillyusb_send_opcode(xdev, chan_num,
+ OPCODE_SET_CHECKPOINT,
+ checkpoint);
+
+ if (rc)
+ break;
+ }
+
+ if (bytes_done == count ||
+ (left_to_sleep <= 0 && bytes_done))
+ break;
+
+ /*
+ * Reaching here means that the FIFO was empty when
+ * fifo_read() returned, but not necessarily right now. Error
+ * and EOF are checked and reported only now, so that no data
+ * that managed its way to the FIFO is lost.
+ */
+
+ if (!READ_ONCE(chan->read_data_ok)) { /* FPGA has sent EOF */
+ /* Has data slipped into the FIFO since fifo_read()? */
+ smp_rmb();
+ if (READ_ONCE(fifo->fill))
+ continue;
+
+ rc = 0;
+ break;
+ }
+
+ if (xdev->error) {
+ rc = xdev->error;
+ break;
+ }
+
+ if (filp->f_flags & O_NONBLOCK) {
+ rc = -EAGAIN;
+ break;
+ }
+
+ if (!sent_set_push) {
+ rc = xillyusb_send_opcode(xdev, chan_num,
+ OPCODE_SET_PUSH,
+ complete_checkpoint);
+
+ if (rc)
+ break;
+
+ sent_set_push = true;
+ }
+
+ if (left_to_sleep > 0) {
+ /*
+ * Note that when xdev->error is set (e.g. when the
+ * device is unplugged), read_data_ok turns zero and
+ * fifo->waitq is awaken.
+ * Therefore no special attention to xdev->error.
+ */
+
+ rc = wait_event_interruptible_timeout
+ (fifo->waitq,
+ fifo->fill || !chan->read_data_ok,
+ left_to_sleep);
+ } else { /* bytes_done == 0 */
+ /* Tell FPGA to send anything it has */
+ rc = request_read_anything(chan, OPCODE_UPDATE_PUSH);
+
+ if (rc)
+ break;
+
+ rc = wait_event_interruptible
+ (fifo->waitq,
+ fifo->fill || !chan->read_data_ok);
+ }
+
+ if (rc < 0) {
+ rc = -EINTR;
+ break;
+ }
+ }
+
+ if (((filp->f_flags & O_NONBLOCK) || chan->poll_used) &&
+ !READ_ONCE(fifo->fill))
+ request_read_anything(chan, OPCODE_SET_PUSH);
+
+ mutex_unlock(&chan->in_mutex);
+
+ if (bytes_done)
+ return bytes_done;
+
+ return rc;
+}
+
+static int xillyusb_flush(struct file *filp, fl_owner_t id)
+{
+ struct xillyusb_channel *chan = filp->private_data;
+ int rc;
+
+ if (!(filp->f_mode & FMODE_WRITE))
+ return 0;
+
+ rc = mutex_lock_interruptible(&chan->out_mutex);
+
+ if (rc)
+ return rc;
+
+ /*
+ * One second's timeout on flushing. Interrupts are ignored, because if
+ * the user pressed CTRL-C, that interrupt will still be in flight by
+ * the time we reach here, and the opportunity to flush is lost.
+ */
+ rc = flush_downstream(chan, HZ, false);
+
+ mutex_unlock(&chan->out_mutex);
+
+ if (rc == -ETIMEDOUT) {
+ /* The things you do to use dev_warn() and not pr_warn() */
+ struct xillyusb_dev *xdev = chan->xdev;
+
+ mutex_lock(&chan->lock);
+ if (!xdev->error)
+ dev_warn(xdev->dev,
+ "Timed out while flushing. Output data may be lost.\n");
+ mutex_unlock(&chan->lock);
+ }
+
+ return rc;
+}
+
+static ssize_t xillyusb_write(struct file *filp, const char __user *userbuf,
+ size_t count, loff_t *f_pos)
+{
+ struct xillyusb_channel *chan = filp->private_data;
+ struct xillyusb_dev *xdev = chan->xdev;
+ struct xillyfifo *fifo = &chan->out_ep->fifo;
+ int rc;
+
+ rc = mutex_lock_interruptible(&chan->out_mutex);
+
+ if (rc)
+ return rc;
+
+ while (1) {
+ if (xdev->error) {
+ rc = xdev->error;
+ break;
+ }
+
+ if (count == 0)
+ break;
+
+ rc = fifo_write(fifo, (__force void *)userbuf, count,
+ xilly_copy_from_user);
+
+ if (rc != 0)
+ break;
+
+ if (filp->f_flags & O_NONBLOCK) {
+ rc = -EAGAIN;
+ break;
+ }
+
+ if (wait_event_interruptible
+ (fifo->waitq,
+ fifo->fill != fifo->size || xdev->error)) {
+ rc = -EINTR;
+ break;
+ }
+ }
+
+ if (rc < 0)
+ goto done;
+
+ chan->out_bytes += rc;
+
+ if (rc) {
+ try_queue_bulk_out(chan->out_ep);
+ chan->flushed = 0;
+ }
+
+ if (chan->out_synchronous) {
+ int flush_rc = flush_downstream(chan, 0, true);
+
+ if (flush_rc && !rc)
+ rc = flush_rc;
+ }
+
+done:
+ mutex_unlock(&chan->out_mutex);
+
+ return rc;
+}
+
+static int xillyusb_release(struct inode *inode, struct file *filp)
+{
+ struct xillyusb_channel *chan = filp->private_data;
+ struct xillyusb_dev *xdev = chan->xdev;
+ int rc_read = 0, rc_write = 0;
+
+ if (filp->f_mode & FMODE_READ) {
+ struct xillyfifo *in_fifo = chan->in_fifo;
+
+ rc_read = xillyusb_send_opcode(xdev, (chan->chan_idx << 1) | 1,
+ OPCODE_CLOSE, 0);
+ /*
+ * If rc_read is nonzero, xdev->error indicates a global
+ * device error. The error is reported later, so that
+ * resources are freed.
+ *
+ * Looping on wait_event_interruptible() kinda breaks the idea
+ * of being interruptible, and this should have been
+ * wait_event(). Only it's being waken with
+ * wake_up_interruptible() for the sake of other uses. If
+ * there's a global device error, chan->read_data_ok is
+ * deasserted and the wait queue is awaken, so this is covered.
+ */
+
+ while (wait_event_interruptible(in_fifo->waitq,
+ !chan->read_data_ok))
+ ; /* Empty loop */
+
+ safely_assign_in_fifo(chan, NULL);
+ fifo_mem_release(in_fifo);
+ kfree(in_fifo);
+
+ mutex_lock(&chan->lock);
+ chan->open_for_read = 0;
+ mutex_unlock(&chan->lock);
+ }
+
+ if (filp->f_mode & FMODE_WRITE) {
+ struct xillyusb_endpoint *ep = chan->out_ep;
+ /*
+ * chan->flushing isn't zeroed. If the pre-release flush timed
+ * out, a cancel request will be sent before the next
+ * OPCODE_SET_CHECKPOINT (i.e. when the file is opened again).
+ * This is despite that the FPGA forgets about the checkpoint
+ * request as the file closes. Still, in an exceptional race
+ * condition, the FPGA could send an OPCODE_REACHED_CHECKPOINT
+ * just before closing that would reach the host after the
+ * file has re-opened.
+ */
+
+ mutex_lock(&chan->lock);
+ chan->out_ep = NULL;
+ mutex_unlock(&chan->lock);
+
+ endpoint_quiesce(ep);
+ endpoint_dealloc(ep);
+
+ /* See comments on rc_read above */
+ rc_write = xillyusb_send_opcode(xdev, chan->chan_idx << 1,
+ OPCODE_CLOSE, 0);
+
+ mutex_lock(&chan->lock);
+ chan->open_for_write = 0;
+ mutex_unlock(&chan->lock);
+ }
+
+ kref_put(&xdev->kref, cleanup_dev);
+
+ return rc_read ? rc_read : rc_write;
+}
+
+/*
+ * Xillybus' API allows device nodes to be seekable, giving the user
+ * application access to a RAM array on the FPGA (or logic emulating it).
+ */
+
+static loff_t xillyusb_llseek(struct file *filp, loff_t offset, int whence)
+{
+ struct xillyusb_channel *chan = filp->private_data;
+ struct xillyusb_dev *xdev = chan->xdev;
+ loff_t pos = filp->f_pos;
+ int rc = 0;
+ unsigned int log2_element_size = chan->readable ?
+ chan->in_log2_element_size : chan->out_log2_element_size;
+
+ /*
+ * Take both mutexes not allowing interrupts, since it seems like
+ * common applications don't expect an -EINTR here. Besides, multiple
+ * access to a single file descriptor on seekable devices is a mess
+ * anyhow.
+ */
+
+ mutex_lock(&chan->out_mutex);
+ mutex_lock(&chan->in_mutex);
+
+ switch (whence) {
+ case SEEK_SET:
+ pos = offset;
+ break;
+ case SEEK_CUR:
+ pos += offset;
+ break;
+ case SEEK_END:
+ pos = offset; /* Going to the end => to the beginning */
+ break;
+ default:
+ rc = -EINVAL;
+ goto end;
+ }
+
+ /* In any case, we must finish on an element boundary */
+ if (pos & ((1 << log2_element_size) - 1)) {
+ rc = -EINVAL;
+ goto end;
+ }
+
+ rc = xillyusb_send_opcode(xdev, chan->chan_idx << 1,
+ OPCODE_SET_ADDR,
+ pos >> log2_element_size);
+
+ if (rc)
+ goto end;
+
+ if (chan->writable) {
+ chan->flushed = 0;
+ rc = flush_downstream(chan, HZ, false);
+ }
+
+end:
+ mutex_unlock(&chan->out_mutex);
+ mutex_unlock(&chan->in_mutex);
+
+ if (rc) /* Return error after releasing mutexes */
+ return rc;
+
+ filp->f_pos = pos;
+
+ return pos;
+}
+
+static __poll_t xillyusb_poll(struct file *filp, poll_table *wait)
+{
+ struct xillyusb_channel *chan = filp->private_data;
+ __poll_t mask = 0;
+
+ if (chan->in_fifo)
+ poll_wait(filp, &chan->in_fifo->waitq, wait);
+
+ if (chan->out_ep)
+ poll_wait(filp, &chan->out_ep->fifo.waitq, wait);
+
+ /*
+ * If this is the first time poll() is called, and the file is
+ * readable, set the relevant flag. Also tell the FPGA to send all it
+ * has, to kickstart the mechanism that ensures there's always some
+ * data in in_fifo unless the stream is dry end-to-end. Note that the
+ * first poll() may not return a EPOLLIN, even if there's data on the
+ * FPGA. Rather, the data will arrive soon, and trigger the relevant
+ * wait queue.
+ */
+
+ if (!chan->poll_used && chan->in_fifo) {
+ chan->poll_used = 1;
+ request_read_anything(chan, OPCODE_SET_PUSH);
+ }
+
+ /*
+ * poll() won't play ball regarding read() channels which
+ * are synchronous. Allowing that will create situations where data has
+ * been delivered at the FPGA, and users expecting select() to wake up,
+ * which it may not. So make it never work.
+ */
+
+ if (chan->in_fifo && !chan->in_synchronous &&
+ (READ_ONCE(chan->in_fifo->fill) || !chan->read_data_ok))
+ mask |= EPOLLIN | EPOLLRDNORM;
+
+ if (chan->out_ep &&
+ (READ_ONCE(chan->out_ep->fifo.fill) != chan->out_ep->fifo.size))
+ mask |= EPOLLOUT | EPOLLWRNORM;
+
+ if (chan->xdev->error)
+ mask |= EPOLLERR;
+
+ return mask;
+}
+
+static const struct file_operations xillyusb_fops = {
+ .owner = THIS_MODULE,
+ .read = xillyusb_read,
+ .write = xillyusb_write,
+ .open = xillyusb_open,
+ .flush = xillyusb_flush,
+ .release = xillyusb_release,
+ .llseek = xillyusb_llseek,
+ .poll = xillyusb_poll,
+};
+
+static int xillyusb_setup_base_eps(struct xillyusb_dev *xdev)
+{
+ xdev->msg_ep = endpoint_alloc(xdev, MSG_EP_NUM | USB_DIR_OUT,
+ bulk_out_work, 1, 2);
+ if (!xdev->msg_ep)
+ return -ENOMEM;
+
+ if (fifo_init(&xdev->msg_ep->fifo, 13)) /* 8 kiB */
+ goto dealloc;
+
+ xdev->msg_ep->fill_mask = -8; /* 8 bytes granularity */
+
+ xdev->in_ep = endpoint_alloc(xdev, IN_EP_NUM | USB_DIR_IN,
+ bulk_in_work, BUF_SIZE_ORDER, BUFNUM);
+ if (!xdev->in_ep)
+ goto dealloc;
+
+ try_queue_bulk_in(xdev->in_ep);
+
+ return 0;
+
+dealloc:
+ endpoint_dealloc(xdev->msg_ep); /* Also frees FIFO mem if allocated */
+ return -ENOMEM;
+}
+
+static int setup_channels(struct xillyusb_dev *xdev,
+ __le16 *chandesc,
+ int num_channels)
+{
+ struct xillyusb_channel *chan;
+ int i;
+
+ chan = kcalloc(num_channels, sizeof(*chan), GFP_KERNEL);
+ if (!chan)
+ return -ENOMEM;
+
+ xdev->channels = chan;
+
+ for (i = 0; i < num_channels; i++, chan++) {
+ unsigned int in_desc = le16_to_cpu(*chandesc++);
+ unsigned int out_desc = le16_to_cpu(*chandesc++);
+
+ chan->xdev = xdev;
+ mutex_init(&chan->in_mutex);
+ mutex_init(&chan->out_mutex);
+ mutex_init(&chan->lock);
+ init_waitqueue_head(&chan->flushq);
+
+ chan->chan_idx = i;
+
+ if (in_desc & 0x80) { /* Entry is valid */
+ chan->readable = 1;
+ chan->in_synchronous = !!(in_desc & 0x40);
+ chan->in_seekable = !!(in_desc & 0x20);
+ chan->in_log2_element_size = in_desc & 0x0f;
+ chan->in_log2_fifo_size = ((in_desc >> 8) & 0x1f) + 16;
+ }
+
+ /*
+ * A downstream channel should never exist above index 13,
+ * as it would request a nonexistent BULK endpoint > 15.
+ * In the peculiar case that it does, it's ignored silently.
+ */
+
+ if ((out_desc & 0x80) && i < 14) { /* Entry is valid */
+ chan->writable = 1;
+ chan->out_synchronous = !!(out_desc & 0x40);
+ chan->out_seekable = !!(out_desc & 0x20);
+ chan->out_log2_element_size = out_desc & 0x0f;
+ chan->out_log2_fifo_size =
+ ((out_desc >> 8) & 0x1f) + 16;
+ }
+ }
+
+ return 0;
+}
+
+static int xillyusb_discovery(struct usb_interface *interface)
+{
+ int rc;
+ struct xillyusb_dev *xdev = usb_get_intfdata(interface);
+ __le16 bogus_chandesc[2];
+ struct xillyfifo idt_fifo;
+ struct xillyusb_channel *chan;
+ unsigned int idt_len, names_offset;
+ unsigned char *idt;
+ int num_channels;
+
+ rc = xillyusb_send_opcode(xdev, ~0, OPCODE_QUIESCE, 0);
+
+ if (rc) {
+ dev_err(&interface->dev, "Failed to send quiesce request. Aborting.\n");
+ return rc;
+ }
+
+ /* Phase I: Set up one fake upstream channel and obtain IDT */
+
+ /* Set up a fake IDT with one async IN stream */
+ bogus_chandesc[0] = cpu_to_le16(0x80);
+ bogus_chandesc[1] = cpu_to_le16(0);
+
+ rc = setup_channels(xdev, bogus_chandesc, 1);
+
+ if (rc)
+ return rc;
+
+ rc = fifo_init(&idt_fifo, LOG2_IDT_FIFO_SIZE);
+
+ if (rc)
+ return rc;
+
+ chan = xdev->channels;
+
+ chan->in_fifo = &idt_fifo;
+ chan->read_data_ok = 1;
+
+ xdev->num_channels = 1;
+
+ rc = xillyusb_send_opcode(xdev, ~0, OPCODE_REQ_IDT, 0);
+
+ if (rc) {
+ dev_err(&interface->dev, "Failed to send IDT request. Aborting.\n");
+ goto unfifo;
+ }
+
+ rc = wait_event_interruptible_timeout(idt_fifo.waitq,
+ !chan->read_data_ok,
+ XILLY_RESPONSE_TIMEOUT);
+
+ if (xdev->error) {
+ rc = xdev->error;
+ goto unfifo;
+ }
+
+ if (rc < 0) {
+ rc = -EINTR; /* Interrupt on probe method? Interesting. */
+ goto unfifo;
+ }
+
+ if (chan->read_data_ok) {
+ rc = -ETIMEDOUT;
+ dev_err(&interface->dev, "No response from FPGA. Aborting.\n");
+ goto unfifo;
+ }
+
+ idt_len = READ_ONCE(idt_fifo.fill);
+ idt = kmalloc(idt_len, GFP_KERNEL);
+
+ if (!idt) {
+ rc = -ENOMEM;
+ goto unfifo;
+ }
+
+ fifo_read(&idt_fifo, idt, idt_len, xilly_memcpy);
+
+ if (crc32_le(~0, idt, idt_len) != 0) {
+ dev_err(&interface->dev, "IDT failed CRC check. Aborting.\n");
+ rc = -ENODEV;
+ goto unidt;
+ }
+
+ if (*idt > 0x90) {
+ dev_err(&interface->dev, "No support for IDT version 0x%02x. Maybe the xillyusb driver needs an upgrade. Aborting.\n",
+ (int)*idt);
+ rc = -ENODEV;
+ goto unidt;
+ }
+
+ /* Phase II: Set up the streams as defined in IDT */
+
+ num_channels = le16_to_cpu(*((__le16 *)(idt + 1)));
+ names_offset = 3 + num_channels * 4;
+ idt_len -= 4; /* Exclude CRC */
+
+ if (idt_len < names_offset) {
+ dev_err(&interface->dev, "IDT too short. This is exceptionally weird, because its CRC is OK\n");
+ rc = -ENODEV;
+ goto unidt;
+ }
+
+ rc = setup_channels(xdev, (void *)idt + 3, num_channels);
+
+ if (rc)
+ goto unidt;
+
+ /*
+ * Except for wildly misbehaving hardware, or if it was disconnected
+ * just after responding with the IDT, there is no reason for any
+ * work item to be running now. To be sure that xdev->channels
+ * is updated on anything that might run in parallel, flush the
+ * workqueue, which rarely does anything.
+ */
+ flush_workqueue(xdev->workq);
+
+ xdev->num_channels = num_channels;
+
+ fifo_mem_release(&idt_fifo);
+ kfree(chan);
+
+ rc = xillybus_init_chrdev(&interface->dev, &xillyusb_fops,
+ THIS_MODULE, xdev,
+ idt + names_offset,
+ idt_len - names_offset,
+ num_channels,
+ xillyname, true);
+
+ kfree(idt);
+
+ return rc;
+
+unidt:
+ kfree(idt);
+
+unfifo:
+ safely_assign_in_fifo(chan, NULL);
+ fifo_mem_release(&idt_fifo);
+
+ return rc;
+}
+
+static int xillyusb_probe(struct usb_interface *interface,
+ const struct usb_device_id *id)
+{
+ struct xillyusb_dev *xdev;
+ int rc;
+
+ xdev = kzalloc(sizeof(*xdev), GFP_KERNEL);
+ if (!xdev)
+ return -ENOMEM;
+
+ kref_init(&xdev->kref);
+ mutex_init(&xdev->process_in_mutex);
+ mutex_init(&xdev->msg_mutex);
+
+ xdev->udev = usb_get_dev(interface_to_usbdev(interface));
+ xdev->dev = &interface->dev;
+ xdev->error = 0;
+ spin_lock_init(&xdev->error_lock);
+ xdev->in_counter = 0;
+ xdev->in_bytes_left = 0;
+ xdev->workq = alloc_workqueue(xillyname, WQ_HIGHPRI, 0);
+
+ if (!xdev->workq) {
+ dev_err(&interface->dev, "Failed to allocate work queue\n");
+ rc = -ENOMEM;
+ goto fail;
+ }
+
+ INIT_WORK(&xdev->wakeup_workitem, wakeup_all);
+
+ usb_set_intfdata(interface, xdev);
+
+ rc = xillyusb_setup_base_eps(xdev);
+ if (rc)
+ goto fail;
+
+ rc = xillyusb_discovery(interface);
+ if (rc)
+ goto latefail;
+
+ return 0;
+
+latefail:
+ endpoint_quiesce(xdev->in_ep);
+ endpoint_quiesce(xdev->msg_ep);
+
+fail:
+ usb_set_intfdata(interface, NULL);
+ kref_put(&xdev->kref, cleanup_dev);
+ return rc;
+}
+
+static void xillyusb_disconnect(struct usb_interface *interface)
+{
+ struct xillyusb_dev *xdev = usb_get_intfdata(interface);
+ struct xillyusb_endpoint *msg_ep = xdev->msg_ep;
+ struct xillyfifo *fifo = &msg_ep->fifo;
+ int rc;
+ int i;
+
+ xillybus_cleanup_chrdev(xdev, &interface->dev);
+
+ /*
+ * Try to send OPCODE_QUIESCE, which will fail silently if the device
+ * was disconnected, but makes sense on module unload.
+ */
+
+ msg_ep->wake_on_drain = true;
+ xillyusb_send_opcode(xdev, ~0, OPCODE_QUIESCE, 0);
+
+ /*
+ * If the device has been disconnected, sending the opcode causes
+ * a global device error with xdev->error, if such error didn't
+ * occur earlier. Hence timing out means that the USB link is fine,
+ * but somehow the message wasn't sent. Should never happen.
+ */
+
+ rc = wait_event_interruptible_timeout(fifo->waitq,
+ msg_ep->drained || xdev->error,
+ XILLY_RESPONSE_TIMEOUT);
+
+ if (!rc)
+ dev_err(&interface->dev,
+ "Weird timeout condition on sending quiesce request.\n");
+
+ report_io_error(xdev, -ENODEV); /* Discourage further activity */
+
+ /*
+ * This device driver is declared with soft_unbind set, or else
+ * sending OPCODE_QUIESCE above would always fail. The price is
+ * that the USB framework didn't kill outstanding URBs, so it has
+ * to be done explicitly before returning from this call.
+ */
+
+ for (i = 0; i < xdev->num_channels; i++) {
+ struct xillyusb_channel *chan = &xdev->channels[i];
+
+ /*
+ * Lock taken to prevent chan->out_ep from changing. It also
+ * ensures xillyusb_open() and xillyusb_flush() don't access
+ * xdev->dev after being nullified below.
+ */
+ mutex_lock(&chan->lock);
+ if (chan->out_ep)
+ endpoint_quiesce(chan->out_ep);
+ mutex_unlock(&chan->lock);
+ }
+
+ endpoint_quiesce(xdev->in_ep);
+ endpoint_quiesce(xdev->msg_ep);
+
+ usb_set_intfdata(interface, NULL);
+
+ xdev->dev = NULL;
+
+ kref_put(&xdev->kref, cleanup_dev);
+}
+
+static struct usb_driver xillyusb_driver = {
+ .name = xillyname,
+ .id_table = xillyusb_table,
+ .probe = xillyusb_probe,
+ .disconnect = xillyusb_disconnect,
+ .soft_unbind = 1,
+};
+
+static int __init xillyusb_init(void)
+{
+ int rc = 0;
+
+ if (LOG2_INITIAL_FIFO_BUF_SIZE > PAGE_SHIFT)
+ fifo_buf_order = LOG2_INITIAL_FIFO_BUF_SIZE - PAGE_SHIFT;
+ else
+ fifo_buf_order = 0;
+
+ rc = usb_register(&xillyusb_driver);
+
+ return rc;
+}
+
+static void __exit xillyusb_exit(void)
+{
+ usb_deregister(&xillyusb_driver);
+}
+
+module_init(xillyusb_init);
+module_exit(xillyusb_exit);
--
2.17.1