diff options
author | Eli Billauer <eli.billauer@gmail.com> | 2021-05-26 13:03:11 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-27 14:07:41 +0200 |
commit | a53d1202aef122894b6e46116a92174a9123db5d (patch) | |
tree | 7e98e90cd3515dc9974940ca2d0eec981225990f | |
parent | 8cb5d216ab3365bc85aac65da27f1c2b3dd6f366 (diff) | |
download | linux-a53d1202aef122894b6e46116a92174a9123db5d.tar.bz2 |
char: xillybus: Add driver for XillyUSB (Xillybus variant for USB)
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>
Link: https://lore.kernel.org/r/20210526100311.56327-3-eli.billauer@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/char/xillybus/Kconfig | 14 | ||||
-rw-r--r-- | drivers/char/xillybus/Makefile | 1 | ||||
-rw-r--r-- | drivers/char/xillybus/xillyusb.c | 2260 |
3 files changed, 2275 insertions, 0 deletions
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); |