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xillybus_core.c
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/*
* linux/drivers/misc/xillybus_core.c
*
* Copyright 2011 Xillybus Ltd, http://xillybus.com
*
* Driver for the Xillybus 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.
*
* This program is free software; you can redistribute it and/or modify
* it under the smems of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*/
#include <linux/list.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/crc32.h>
#include <linux/poll.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include "xillybus.h"
MODULE_DESCRIPTION("Xillybus core functions");
MODULE_AUTHOR("Eli Billauer, Xillybus Ltd.");
MODULE_VERSION("1.07");
MODULE_ALIAS("xillybus_core");
MODULE_LICENSE("GPL v2");
/* General timeout is 100 ms, rx timeout is 10 ms */
#define XILLY_RX_TIMEOUT (10*HZ/1000)
#define XILLY_TIMEOUT (100*HZ/1000)
#define fpga_msg_ctrl_reg 0x0008
#define fpga_dma_control_reg 0x0020
#define fpga_dma_bufno_reg 0x0024
#define fpga_dma_bufaddr_lowaddr_reg 0x0028
#define fpga_dma_bufaddr_highaddr_reg 0x002c
#define fpga_buf_ctrl_reg 0x0030
#define fpga_buf_offset_reg 0x0034
#define fpga_endian_reg 0x0040
#define XILLYMSG_OPCODE_RELEASEBUF 1
#define XILLYMSG_OPCODE_QUIESCEACK 2
#define XILLYMSG_OPCODE_FIFOEOF 3
#define XILLYMSG_OPCODE_FATAL_ERROR 4
#define XILLYMSG_OPCODE_NONEMPTY 5
static const char xillyname[] = "xillybus";
static struct class *xillybus_class;
/*
* ep_list_lock is the last lock to be taken; No other lock requests are
* allowed while holding it. It merely protects list_of_endpoints, and not
* the endpoints listed in it.
*/
static LIST_HEAD(list_of_endpoints);
static struct mutex ep_list_lock;
static struct workqueue_struct *xillybus_wq;
/*
* Locking scheme: Mutexes protect invocations of character device methods.
* If both locks are taken, wr_mutex is taken first, rd_mutex second.
*
* wr_spinlock protects wr_*_buf_idx, wr_empty, wr_sleepy, wr_ready and the
* buffers' end_offset fields against changes made by IRQ handler (and in
* theory, other file request handlers, but the mutex handles that). Nothing
* else.
* They are held for short direct memory manipulations. Needless to say,
* no mutex locking is allowed when a spinlock is held.
*
* rd_spinlock does the same with rd_*_buf_idx, rd_empty and end_offset.
*
* register_mutex is endpoint-specific, and is held when non-atomic
* register operations are performed. wr_mutex and rd_mutex may be
* held when register_mutex is taken, but none of the spinlocks. Note that
* register_mutex doesn't protect against sporadic buf_ctrl_reg writes
* which are unrelated to buf_offset_reg, since they are harmless.
*
* Blocking on the wait queues is allowed with mutexes held, but not with
* spinlocks.
*
* Only interruptible blocking is allowed on mutexes and wait queues.
*
* All in all, the locking order goes (with skips allowed, of course):
* wr_mutex -> rd_mutex -> register_mutex -> wr_spinlock -> rd_spinlock
*/
static void malformed_message(struct xilly_endpoint *endpoint, u32 *buf)
{
int opcode;
int msg_channel, msg_bufno, msg_data, msg_dir;
opcode = (buf[0] >> 24) & 0xff;
msg_dir = buf[0] & 1;
msg_channel = (buf[0] >> 1) & 0x7ff;
msg_bufno = (buf[0] >> 12) & 0x3ff;
msg_data = buf[1] & 0xfffffff;
dev_warn(endpoint->dev,
"Malformed message (skipping): opcode=%d, channel=%03x, dir=%d, bufno=%03x, data=%07x\n",
opcode, msg_channel, msg_dir, msg_bufno, msg_data);
}
/*
* xillybus_isr assumes the interrupt is allocated exclusively to it,
* which is the natural case MSI and several other hardware-oriented
* interrupts. Sharing is not allowed.
*/
irqreturn_t xillybus_isr(int irq, void *data)
{
struct xilly_endpoint *ep = data;
u32 *buf;
unsigned int buf_size;
int i;
int opcode;
unsigned int msg_channel, msg_bufno, msg_data, msg_dir;
struct xilly_channel *channel;
buf = ep->msgbuf_addr;
buf_size = ep->msg_buf_size/sizeof(u32);
ep->ephw->hw_sync_sgl_for_cpu(ep,
ep->msgbuf_dma_addr,
ep->msg_buf_size,
DMA_FROM_DEVICE);
for (i = 0; i < buf_size; i += 2) {
if (((buf[i+1] >> 28) & 0xf) != ep->msg_counter) {
malformed_message(ep, &buf[i]);
dev_warn(ep->dev,
"Sending a NACK on counter %x (instead of %x) on entry %d\n",
((buf[i+1] >> 28) & 0xf),
ep->msg_counter,
i/2);
if (++ep->failed_messages > 10) {
dev_err(ep->dev,
"Lost sync with interrupt messages. Stopping.\n");
} else {
ep->ephw->hw_sync_sgl_for_device(
ep,
ep->msgbuf_dma_addr,
ep->msg_buf_size,
DMA_FROM_DEVICE);
iowrite32(0x01, /* Message NACK */
ep->registers + fpga_msg_ctrl_reg);
}
return IRQ_HANDLED;
} else if (buf[i] & (1 << 22)) /* Last message */
break;
}
if (i >= buf_size) {
dev_err(ep->dev, "Bad interrupt message. Stopping.\n");
return IRQ_HANDLED;
}
buf_size = i + 2;
for (i = 0; i < buf_size; i += 2) { /* Scan through messages */
opcode = (buf[i] >> 24) & 0xff;
msg_dir = buf[i] & 1;
msg_channel = (buf[i] >> 1) & 0x7ff;
msg_bufno = (buf[i] >> 12) & 0x3ff;
msg_data = buf[i+1] & 0xfffffff;
switch (opcode) {
case XILLYMSG_OPCODE_RELEASEBUF:
if ((msg_channel > ep->num_channels) ||
(msg_channel == 0)) {
malformed_message(ep, &buf[i]);
break;
}
channel = ep->channels[msg_channel];
if (msg_dir) { /* Write channel */
if (msg_bufno >= channel->num_wr_buffers) {
malformed_message(ep, &buf[i]);
break;
}
spin_lock(&channel->wr_spinlock);
channel->wr_buffers[msg_bufno]->end_offset =
msg_data;
channel->wr_fpga_buf_idx = msg_bufno;
channel->wr_empty = 0;
channel->wr_sleepy = 0;
spin_unlock(&channel->wr_spinlock);
wake_up_interruptible(&channel->wr_wait);
} else {
/* Read channel */
if (msg_bufno >= channel->num_rd_buffers) {
malformed_message(ep, &buf[i]);
break;
}
spin_lock(&channel->rd_spinlock);
channel->rd_fpga_buf_idx = msg_bufno;
channel->rd_full = 0;
spin_unlock(&channel->rd_spinlock);
wake_up_interruptible(&channel->rd_wait);
if (!channel->rd_synchronous)
queue_delayed_work(
xillybus_wq,
&channel->rd_workitem,
XILLY_RX_TIMEOUT);
}
break;
case XILLYMSG_OPCODE_NONEMPTY:
if ((msg_channel > ep->num_channels) ||
(msg_channel == 0) || (!msg_dir) ||
!ep->channels[msg_channel]->wr_supports_nonempty) {
malformed_message(ep, &buf[i]);
break;
}
channel = ep->channels[msg_channel];
if (msg_bufno >= channel->num_wr_buffers) {
malformed_message(ep, &buf[i]);
break;
}
spin_lock(&channel->wr_spinlock);
if (msg_bufno == channel->wr_host_buf_idx)
channel->wr_ready = 1;
spin_unlock(&channel->wr_spinlock);
wake_up_interruptible(&channel->wr_ready_wait);
break;
case XILLYMSG_OPCODE_QUIESCEACK:
ep->idtlen = msg_data;
wake_up_interruptible(&ep->ep_wait);
break;
case XILLYMSG_OPCODE_FIFOEOF:
if ((msg_channel > ep->num_channels) ||
(msg_channel == 0) || (!msg_dir) ||
!ep->channels[msg_channel]->num_wr_buffers) {
malformed_message(ep, &buf[i]);
break;
}
channel = ep->channels[msg_channel];
spin_lock(&channel->wr_spinlock);
channel->wr_eof = msg_bufno;
channel->wr_sleepy = 0;
channel->wr_hangup = channel->wr_empty &&
(channel->wr_host_buf_idx == msg_bufno);
spin_unlock(&channel->wr_spinlock);
wake_up_interruptible(&channel->wr_wait);
break;
case XILLYMSG_OPCODE_FATAL_ERROR:
ep->fatal_error = 1;
wake_up_interruptible(&ep->ep_wait); /* For select() */
dev_err(ep->dev,
"FPGA reported a fatal error. This means that the low-level communication with the device has failed. This hardware problem is most likely unrelated to Xillybus (neither kernel module nor FPGA core), but reports are still welcome. All I/O is aborted.\n");
break;
default:
malformed_message(ep, &buf[i]);
break;
}
}
ep->ephw->hw_sync_sgl_for_device(ep,
ep->msgbuf_dma_addr,
ep->msg_buf_size,
DMA_FROM_DEVICE);
ep->msg_counter = (ep->msg_counter + 1) & 0xf;
ep->failed_messages = 0;
iowrite32(0x03, ep->registers + fpga_msg_ctrl_reg); /* Message ACK */
return IRQ_HANDLED;
}
EXPORT_SYMBOL(xillybus_isr);
/*
* A few trivial memory management functions.
* NOTE: These functions are used only on probe and remove, and therefore
* no locks are applied!
*/
static void xillybus_autoflush(struct work_struct *work);
struct xilly_alloc_state {
void *salami;
int left_of_salami;
int nbuffer;
enum dma_data_direction direction;
u32 regdirection;
};
static int xilly_get_dma_buffers(struct xilly_endpoint *ep,
struct xilly_alloc_state *s,
struct xilly_buffer **buffers,
int bufnum, int bytebufsize)
{
int i, rc;
dma_addr_t dma_addr;
struct device *dev = ep->dev;
struct xilly_buffer *this_buffer = NULL; /* Init to silence warning */
if (buffers) { /* Not the message buffer */
this_buffer = devm_kcalloc(dev, bufnum,
sizeof(struct xilly_buffer),
GFP_KERNEL);
if (!this_buffer)
return -ENOMEM;
}
for (i = 0; i < bufnum; i++) {
/*
* Buffers are expected in descending size order, so there
* is either enough space for this buffer or none at all.
*/
if ((s->left_of_salami < bytebufsize) &&
(s->left_of_salami > 0)) {
dev_err(ep->dev,
"Corrupt buffer allocation in IDT. Aborting.\n");
return -ENODEV;
}
if (s->left_of_salami == 0) {
int allocorder, allocsize;
allocsize = PAGE_SIZE;
allocorder = 0;
while (bytebufsize > allocsize) {
allocsize *= 2;
allocorder++;
}
s->salami = (void *) devm_get_free_pages(
dev,
GFP_KERNEL | __GFP_DMA32 | __GFP_ZERO,
allocorder);
if (!s->salami)
return -ENOMEM;
s->left_of_salami = allocsize;
}
rc = ep->ephw->map_single(ep, s->salami,
bytebufsize, s->direction,
&dma_addr);
if (rc)
return rc;
iowrite32((u32) (dma_addr & 0xffffffff),
ep->registers + fpga_dma_bufaddr_lowaddr_reg);
iowrite32(((u32) ((((u64) dma_addr) >> 32) & 0xffffffff)),
ep->registers + fpga_dma_bufaddr_highaddr_reg);
if (buffers) { /* Not the message buffer */
this_buffer->addr = s->salami;
this_buffer->dma_addr = dma_addr;
buffers[i] = this_buffer++;
iowrite32(s->regdirection | s->nbuffer++,
ep->registers + fpga_dma_bufno_reg);
} else {
ep->msgbuf_addr = s->salami;
ep->msgbuf_dma_addr = dma_addr;
ep->msg_buf_size = bytebufsize;
iowrite32(s->regdirection,
ep->registers + fpga_dma_bufno_reg);
}
s->left_of_salami -= bytebufsize;
s->salami += bytebufsize;
}
return 0;
}
static int xilly_setupchannels(struct xilly_endpoint *ep,
unsigned char *chandesc,
int entries)
{
struct device *dev = ep->dev;
int i, entry, rc;
struct xilly_channel *channel;
int channelnum, bufnum, bufsize, format, is_writebuf;
int bytebufsize;
int synchronous, allowpartial, exclusive_open, seekable;
int supports_nonempty;
int msg_buf_done = 0;
struct xilly_alloc_state rd_alloc = {
.salami = NULL,
.left_of_salami = 0,
.nbuffer = 1,
.direction = DMA_TO_DEVICE,
.regdirection = 0,
};
struct xilly_alloc_state wr_alloc = {
.salami = NULL,
.left_of_salami = 0,
.nbuffer = 1,
.direction = DMA_FROM_DEVICE,
.regdirection = 0x80000000,
};
channel = devm_kcalloc(dev, ep->num_channels,
sizeof(struct xilly_channel), GFP_KERNEL);
if (!channel)
return -ENOMEM;
ep->channels = devm_kcalloc(dev, ep->num_channels + 1,
sizeof(struct xilly_channel *),
GFP_KERNEL);
if (!ep->channels)
return -ENOMEM;
ep->channels[0] = NULL; /* Channel 0 is message buf. */
/* Initialize all channels with defaults */
for (i = 1; i <= ep->num_channels; i++) {
channel->wr_buffers = NULL;
channel->rd_buffers = NULL;
channel->num_wr_buffers = 0;
channel->num_rd_buffers = 0;
channel->wr_fpga_buf_idx = -1;
channel->wr_host_buf_idx = 0;
channel->wr_host_buf_pos = 0;
channel->wr_empty = 1;
channel->wr_ready = 0;
channel->wr_sleepy = 1;
channel->rd_fpga_buf_idx = 0;
channel->rd_host_buf_idx = 0;
channel->rd_host_buf_pos = 0;
channel->rd_full = 0;
channel->wr_ref_count = 0;
channel->rd_ref_count = 0;
spin_lock_init(&channel->wr_spinlock);
spin_lock_init(&channel->rd_spinlock);
mutex_init(&channel->wr_mutex);
mutex_init(&channel->rd_mutex);
init_waitqueue_head(&channel->rd_wait);
init_waitqueue_head(&channel->wr_wait);
init_waitqueue_head(&channel->wr_ready_wait);
INIT_DELAYED_WORK(&channel->rd_workitem, xillybus_autoflush);
channel->endpoint = ep;
channel->chan_num = i;
channel->log2_element_size = 0;
ep->channels[i] = channel++;
}
for (entry = 0; entry < entries; entry++, chandesc += 4) {
struct xilly_buffer **buffers = NULL;
is_writebuf = chandesc[0] & 0x01;
channelnum = (chandesc[0] >> 1) | ((chandesc[1] & 0x0f) << 7);
format = (chandesc[1] >> 4) & 0x03;
allowpartial = (chandesc[1] >> 6) & 0x01;
synchronous = (chandesc[1] >> 7) & 0x01;
bufsize = 1 << (chandesc[2] & 0x1f);
bufnum = 1 << (chandesc[3] & 0x0f);
exclusive_open = (chandesc[2] >> 7) & 0x01;
seekable = (chandesc[2] >> 6) & 0x01;
supports_nonempty = (chandesc[2] >> 5) & 0x01;
if ((channelnum > ep->num_channels) ||
((channelnum == 0) && !is_writebuf)) {
dev_err(ep->dev,
"IDT requests channel out of range. Aborting.\n");
return -ENODEV;
}
channel = ep->channels[channelnum]; /* NULL for msg channel */
if (!is_writebuf || channelnum > 0) {
channel->log2_element_size = ((format > 2) ?
2 : format);
bytebufsize = channel->rd_buf_size = bufsize *
(1 << channel->log2_element_size);
buffers = devm_kcalloc(dev, bufnum,
sizeof(struct xilly_buffer *),
GFP_KERNEL);
if (!buffers)
return -ENOMEM;
} else {
bytebufsize = bufsize << 2;
}
if (!is_writebuf) {
channel->num_rd_buffers = bufnum;
channel->rd_allow_partial = allowpartial;
channel->rd_synchronous = synchronous;
channel->rd_exclusive_open = exclusive_open;
channel->seekable = seekable;
channel->rd_buffers = buffers;
rc = xilly_get_dma_buffers(ep, &rd_alloc, buffers,
bufnum, bytebufsize);
} else if (channelnum > 0) {
channel->num_wr_buffers = bufnum;
channel->seekable = seekable;
channel->wr_supports_nonempty = supports_nonempty;
channel->wr_allow_partial = allowpartial;
channel->wr_synchronous = synchronous;
channel->wr_exclusive_open = exclusive_open;
channel->wr_buffers = buffers;
rc = xilly_get_dma_buffers(ep, &wr_alloc, buffers,
bufnum, bytebufsize);
} else {
rc = xilly_get_dma_buffers(ep, &wr_alloc, NULL,
bufnum, bytebufsize);
msg_buf_done++;
}
if (rc)
return -ENOMEM;
}
if (!msg_buf_done) {
dev_err(ep->dev,
"Corrupt IDT: No message buffer. Aborting.\n");
return -ENODEV;
}
return 0;
}
static int xilly_scan_idt(struct xilly_endpoint *endpoint,
struct xilly_idt_handle *idt_handle)
{
int count = 0;
unsigned char *idt = endpoint->channels[1]->wr_buffers[0]->addr;
unsigned char *end_of_idt = idt + endpoint->idtlen - 4;
unsigned char *scan;
int len;
scan = idt;
idt_handle->idt = idt;
scan++; /* Skip version number */
while ((scan <= end_of_idt) && *scan) {
while ((scan <= end_of_idt) && *scan++)
/* Do nothing, just scan thru string */;
count++;
}
scan++;
if (scan > end_of_idt) {
dev_err(endpoint->dev,
"IDT device name list overflow. Aborting.\n");
return -ENODEV;
}
idt_handle->chandesc = scan;
len = endpoint->idtlen - (3 + ((int) (scan - idt)));
if (len & 0x03) {
dev_err(endpoint->dev,
"Corrupt IDT device name list. Aborting.\n");
return -ENODEV;
}
idt_handle->entries = len >> 2;
endpoint->num_channels = count;
return 0;
}
static int xilly_obtain_idt(struct xilly_endpoint *endpoint)
{
struct xilly_channel *channel;
unsigned char *version;
long t;
channel = endpoint->channels[1]; /* This should be generated ad-hoc */
channel->wr_sleepy = 1;
iowrite32(1 |
(3 << 24), /* Opcode 3 for channel 0 = Send IDT */
endpoint->registers + fpga_buf_ctrl_reg);
t = wait_event_interruptible_timeout(channel->wr_wait,
(!channel->wr_sleepy),
XILLY_TIMEOUT);
if (t <= 0) {
dev_err(endpoint->dev, "Failed to obtain IDT. Aborting.\n");
if (endpoint->fatal_error)
return -EIO;
return -ENODEV;
}
endpoint->ephw->hw_sync_sgl_for_cpu(
channel->endpoint,
channel->wr_buffers[0]->dma_addr,
channel->wr_buf_size,
DMA_FROM_DEVICE);
if (channel->wr_buffers[0]->end_offset != endpoint->idtlen) {
dev_err(endpoint->dev,
"IDT length mismatch (%d != %d). Aborting.\n",
channel->wr_buffers[0]->end_offset, endpoint->idtlen);
return -ENODEV;
}
if (crc32_le(~0, channel->wr_buffers[0]->addr,
endpoint->idtlen+1) != 0) {
dev_err(endpoint->dev, "IDT failed CRC check. Aborting.\n");
return -ENODEV;
}
version = channel->wr_buffers[0]->addr;
/* Check version number. Accept anything below 0x82 for now. */
if (*version > 0x82) {
dev_err(endpoint->dev,
"No support for IDT version 0x%02x. Maybe the xillybus driver needs an upgarde. Aborting.\n",
*version);
return -ENODEV;
}
return 0;
}
static ssize_t xillybus_read(struct file *filp, char __user *userbuf,
size_t count, loff_t *f_pos)
{
ssize_t rc;
unsigned long flags;
int bytes_done = 0;
int no_time_left = 0;
long deadline, left_to_sleep;
struct xilly_channel *channel = filp->private_data;
int empty, reached_eof, exhausted, ready;
/* Initializations are there only to silence warnings */
int howmany = 0, bufpos = 0, bufidx = 0, bufferdone = 0;
int waiting_bufidx;
if (channel->endpoint->fatal_error)
return -EIO;
deadline = jiffies + 1 + XILLY_RX_TIMEOUT;
rc = mutex_lock_interruptible(&channel->wr_mutex);
if (rc)
return rc;
while (1) { /* Note that we may drop mutex within this loop */
int bytes_to_do = count - bytes_done;
spin_lock_irqsave(&channel->wr_spinlock, flags);
empty = channel->wr_empty;
ready = !empty || channel->wr_ready;
if (!empty) {
bufidx = channel->wr_host_buf_idx;
bufpos = channel->wr_host_buf_pos;
howmany = ((channel->wr_buffers[bufidx]->end_offset
+ 1) << channel->log2_element_size)
- bufpos;
/* Update wr_host_* to its post-operation state */
if (howmany > bytes_to_do) {
bufferdone = 0;
howmany = bytes_to_do;
channel->wr_host_buf_pos += howmany;
} else {
bufferdone = 1;
channel->wr_host_buf_pos = 0;
if (bufidx == channel->wr_fpga_buf_idx) {
channel->wr_empty = 1;
channel->wr_sleepy = 1;
channel->wr_ready = 0;
}
if (bufidx >= (channel->num_wr_buffers - 1))
channel->wr_host_buf_idx = 0;
else
channel->wr_host_buf_idx++;
}
}
/*
* Marking our situation after the possible changes above,
* for use after releasing the spinlock.
*
* empty = empty before change
* exhasted = empty after possible change
*/
reached_eof = channel->wr_empty &&
(channel->wr_host_buf_idx == channel->wr_eof);
channel->wr_hangup = reached_eof;
exhausted = channel->wr_empty;
waiting_bufidx = channel->wr_host_buf_idx;
spin_unlock_irqrestore(&channel->wr_spinlock, flags);
if (!empty) { /* Go on, now without the spinlock */
if (bufpos == 0) /* Position zero means it's virgin */
channel->endpoint->ephw->hw_sync_sgl_for_cpu(
channel->endpoint,
channel->wr_buffers[bufidx]->dma_addr,
channel->wr_buf_size,
DMA_FROM_DEVICE);
if (copy_to_user(
userbuf,
channel->wr_buffers[bufidx]->addr
+ bufpos, howmany))
rc = -EFAULT;
userbuf += howmany;
bytes_done += howmany;
if (bufferdone) {
channel->endpoint->ephw->hw_sync_sgl_for_device(
channel->endpoint,
channel->wr_buffers[bufidx]->dma_addr,
channel->wr_buf_size,
DMA_FROM_DEVICE);
/*
* Tell FPGA the buffer is done with. It's an
* atomic operation to the FPGA, so what
* happens with other channels doesn't matter,
* and the certain channel is protected with
* the channel-specific mutex.
*/
iowrite32(1 | (channel->chan_num << 1) |
(bufidx << 12),
channel->endpoint->registers +
fpga_buf_ctrl_reg);
}
if (rc) {
mutex_unlock(&channel->wr_mutex);
return rc;
}
}
/* This includes a zero-count return = EOF */
if ((bytes_done >= count) || reached_eof)
break;
if (!exhausted)
continue; /* More in RAM buffer(s)? Just go on. */
if ((bytes_done > 0) &&
(no_time_left ||
(channel->wr_synchronous && channel->wr_allow_partial)))
break;
/*
* Nonblocking read: The "ready" flag tells us that the FPGA
* has data to send. In non-blocking mode, if it isn't on,
* just return. But if there is, we jump directly to the point
* where we ask for the FPGA to send all it has, and wait
* until that data arrives. So in a sense, we *do* block in
* nonblocking mode, but only for a very short time.
*/
if (!no_time_left && (filp->f_flags & O_NONBLOCK)) {
if (bytes_done > 0)
break;
if (ready)
goto desperate;
rc = -EAGAIN;
break;
}
if (!no_time_left || (bytes_done > 0)) {
/*
* Note that in case of an element-misaligned read
* request, offsetlimit will include the last element,
* which will be partially read from.
*/
int offsetlimit = ((count - bytes_done) - 1) >>
channel->log2_element_size;
int buf_elements = channel->wr_buf_size >>
channel->log2_element_size;
/*
* In synchronous mode, always send an offset limit.
* Just don't send a value too big.
*/
if (channel->wr_synchronous) {
/* Don't request more than one buffer */
if (channel->wr_allow_partial &&
(offsetlimit >= buf_elements))
offsetlimit = buf_elements - 1;
/* Don't request more than all buffers */
if (!channel->wr_allow_partial &&
(offsetlimit >=
(buf_elements * channel->num_wr_buffers)))
offsetlimit = buf_elements *
channel->num_wr_buffers - 1;
}
/*
* In asynchronous mode, force early flush of a buffer
* only if that will allow returning a full count. The
* "offsetlimit < ( ... )" rather than "<=" excludes
* requesting a full buffer, which would obviously
* cause a buffer transmission anyhow
*/
if (channel->wr_synchronous ||
(offsetlimit < (buf_elements - 1))) {
mutex_lock(&channel->endpoint->register_mutex);
iowrite32(offsetlimit,
channel->endpoint->registers +
fpga_buf_offset_reg);
iowrite32(1 | (channel->chan_num << 1) |
(2 << 24) | /* 2 = offset limit */
(waiting_bufidx << 12),
channel->endpoint->registers +
fpga_buf_ctrl_reg);
mutex_unlock(&channel->endpoint->
register_mutex);
}
}
/*
* If partial completion is disallowed, there is no point in
* timeout sleeping. Neither if no_time_left is set and
* there's no data.
*/
if (!channel->wr_allow_partial ||
(no_time_left && (bytes_done == 0))) {
/*
* This do-loop will run more than once if another
* thread reasserted wr_sleepy before we got the mutex
* back, so we try again.
*/
do {
mutex_unlock(&channel->wr_mutex);
if (wait_event_interruptible(
channel->wr_wait,
(!channel->wr_sleepy)))
goto interrupted;
if (mutex_lock_interruptible(
&channel->wr_mutex))
goto interrupted;
} while (channel->wr_sleepy);
continue;
interrupted: /* Mutex is not held if got here */
if (channel->endpoint->fatal_error)
return -EIO;
if (bytes_done)
return bytes_done;
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN; /* Don't admit snoozing */
return -EINTR;
}
left_to_sleep = deadline - ((long) jiffies);
/*
* If our time is out, skip the waiting. We may miss wr_sleepy
* being deasserted but hey, almost missing the train is like
* missing it.
*/
if (left_to_sleep > 0) {
left_to_sleep =
wait_event_interruptible_timeout(
channel->wr_wait,
(!channel->wr_sleepy),
left_to_sleep);
if (left_to_sleep > 0) /* wr_sleepy deasserted */
continue;
if (left_to_sleep < 0) { /* Interrupt */
mutex_unlock(&channel->wr_mutex);
if (channel->endpoint->fatal_error)
return -EIO;
if (bytes_done)
return bytes_done;
return -EINTR;
}
}
desperate:
no_time_left = 1; /* We're out of sleeping time. Desperate! */
if (bytes_done == 0) {
/*
* Reaching here means that we allow partial return,
* that we've run out of time, and that we have
* nothing to return.
* So tell the FPGA to send anything it has or gets.
*/
iowrite32(1 | (channel->chan_num << 1) |
(3 << 24) | /* Opcode 3, flush it all! */
(waiting_bufidx << 12),
channel->endpoint->registers +
fpga_buf_ctrl_reg);
}
/*
* Reaching here means that we *do* have data in the buffer,
* but the "partial" flag disallows returning less than
* required. And we don't have as much. So loop again,
* which is likely to end up blocking indefinitely until
* enough data has arrived.
*/
}
mutex_unlock(&channel->wr_mutex);
if (channel->endpoint->fatal_error)
return -EIO;
if (rc)
return rc;
return bytes_done;
}
/*
* The timeout argument takes values as follows:
* >0 : Flush with timeout
* ==0 : Flush, and wait idefinitely for the flush to complete
* <0 : Autoflush: Flush only if there's a single buffer occupied
*/
static int xillybus_myflush(struct xilly_channel *channel, long timeout)
{
int rc;
unsigned long flags;
int end_offset_plus1;
int bufidx, bufidx_minus1;
int i;