Staging: add b3dfg driver
authorDaniel Drake <ddrake@brontes3d.com>
Wed, 28 Jan 2009 14:38:07 +0000 (09:38 -0500)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 3 Apr 2009 21:53:38 +0000 (14:53 -0700)
Initial b3dfg driver development as preformed by Daniel Drake.  All
basic functionality is completed.

Signed-off-by: Justin Bronder <jsbronder@brontes3d.com>
Cc: Daniel Drake <ddrake@brontes3d.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/staging/b3dfg/b3dfg.c [new file with mode: 0644]

diff --git a/drivers/staging/b3dfg/b3dfg.c b/drivers/staging/b3dfg/b3dfg.c
new file mode 100644 (file)
index 0000000..401d7a9
--- /dev/null
@@ -0,0 +1,1049 @@
+ /*
+ * Brontes PCI frame grabber driver
+ *
+ * Copyright (C) 2008 3M Company
+ * Contact: Daniel Drake <ddrake@brontes3d.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/ioctl.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/types.h>
+#include <linux/cdev.h>
+#include <linux/list.h>
+#include <linux/poll.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include <linux/version.h>
+#include <linux/mutex.h>
+
+#include <asm/atomic.h>
+#include <asm/uaccess.h>
+
+/* TODO:
+ * locking
+ * queue/wait buffer presents filltime results for each frame?
+ * counting of dropped frames
+ * review endianness
+ */
+
+#ifdef DEBUG
+#define dbg(msg...) printk(msg)
+#else
+#define dbg(msg...)
+#endif
+
+#define DRIVER_NAME "b3dfg"
+#define PFX DRIVER_NAME ": "
+#define B3DFG_MAX_DEVS 4
+#define B3DFG_NR_TRIPLET_BUFFERS 4
+#define B3DFG_NR_FRAME_BUFFERS (B3DFG_NR_TRIPLET_BUFFERS * 3)
+#define B3DFG_FRAMES_PER_BUFFER 3
+
+#define B3DFG_BAR_REGS 0
+#define B3DFG_REGS_LENGTH 0x10000
+
+#define B3DFG_IOC_MAGIC                        0xb3 /* dfg :-) */
+#define B3DFG_IOCGFRMSZ                        _IOR(B3DFG_IOC_MAGIC, 1, int)
+#define B3DFG_IOCTNUMBUFS              _IO(B3DFG_IOC_MAGIC, 2)
+#define B3DFG_IOCTTRANS                        _IO(B3DFG_IOC_MAGIC, 3)
+#define B3DFG_IOCTQUEUEBUF             _IO(B3DFG_IOC_MAGIC, 4)
+#define B3DFG_IOCTPOLLBUF              _IOWR(B3DFG_IOC_MAGIC, 5, struct b3dfg_poll)
+#define B3DFG_IOCTWAITBUF              _IOWR(B3DFG_IOC_MAGIC, 6, struct b3dfg_wait)
+#define B3DFG_IOCGWANDSTAT             _IOR(B3DFG_IOC_MAGIC, 7, int)
+
+enum {
+       /* number of 4kb pages per frame */
+       B3D_REG_FRM_SIZE = 0x0,
+
+       /* bit 0: set to enable interrupts */
+       B3D_REG_HW_CTRL = 0x4,
+
+       /* bit 0-1 - 1-based ID of next pending frame transfer (0 = nothing pending)
+        * bit 2 indicates the previous DMA transfer has completed
+        * bit 8:15 - counter of number of discarded triplets */
+       B3D_REG_DMA_STS = 0x8,
+
+       /* bit 0: wand status (1 = present, 0 = disconnected) */
+       B3D_REG_WAND_STS = 0xc,
+
+       /* bus address for DMA transfers. lower 2 bits must be zero because DMA
+        * works with 32 bit word size. */
+       B3D_REG_EC220_DMA_ADDR = 0x8000,
+
+       /* bit 20:0 - number of 32 bit words to be transferred
+        * bit 21:31 - reserved */
+       B3D_REG_EC220_TRF_SIZE = 0x8004,
+
+       /* bit 0 - error bit
+        * bit 1 - interrupt bit (set to generate interrupt at end of transfer)
+        * bit 2 - start bit (set to start transfer)
+        * bit 3 - direction (0 = DMA_TO_DEVICE, 1 = DMA_FROM_DEVICE
+        * bit 4:31 - reserved */
+       B3D_REG_EC220_DMA_STS = 0x8008,
+};
+
+enum b3dfg_buffer_state {
+       B3DFG_BUFFER_POLLED = 0,
+       B3DFG_BUFFER_PENDING,
+       B3DFG_BUFFER_POPULATED,
+};
+
+struct b3dfg_buffer {
+       unsigned char *frame[B3DFG_FRAMES_PER_BUFFER];
+       u8 state;
+       struct list_head list;
+};
+
+struct b3dfg_dev {
+       /* no protection needed: all finalized at initialization time */
+       struct pci_dev *pdev;
+    struct cdev chardev;
+    struct class_device *classdev;
+       void __iomem *regs;
+       unsigned int frame_size;
+
+       /* we want to serialize some ioctl operations */
+       struct mutex ioctl_mutex;
+
+       /* preallocated frame buffers */
+       unsigned char *frame_buffer[B3DFG_NR_FRAME_BUFFERS];
+
+       /* buffers_lock protects num_buffers, buffers, buffer_queue */
+       spinlock_t buffer_lock;
+       int num_buffers;
+       struct b3dfg_buffer *buffers;
+       struct list_head buffer_queue;
+
+       wait_queue_head_t buffer_waitqueue;
+
+       atomic_t mapping_count;
+
+       spinlock_t triplets_dropped_lock;
+       unsigned int triplets_dropped;
+
+       /* FIXME: we need some locking here. this could be accessed in parallel
+        * from the queue_buffer ioctl and the interrupt handler. */
+       int cur_dma_frame_idx;
+       dma_addr_t cur_dma_frame_addr;
+
+       unsigned int transmission_enabled:1;
+       unsigned int triplet_ready:1;
+};
+
+static u8 b3dfg_devices[B3DFG_MAX_DEVS];
+
+static struct class *b3dfg_class;
+static dev_t b3dfg_devt;
+
+static const struct pci_device_id b3dfg_ids[] __devinitdata = {
+       { PCI_DEVICE(0x0b3d, 0x0001) },
+
+       /* FIXME: remove this ID once all boards have been moved to 0xb3d.
+        * this is Eureka's vendor ID that we borrowed before we bought our own. */
+       { PCI_DEVICE(0x1901, 0x0001) },
+       { },
+};
+
+/***** user-visible types *****/
+
+struct b3dfg_poll {
+       int buffer_idx;
+       unsigned int triplets_dropped;
+};
+
+struct b3dfg_wait {
+       int buffer_idx;
+       unsigned int timeout;
+       unsigned int triplets_dropped;
+};
+
+/**** register I/O ****/
+
+static u32 b3dfg_read32(struct b3dfg_dev *fgdev, u16 reg)
+{
+       return ioread32(fgdev->regs + reg);
+}
+
+static void b3dfg_write32(struct b3dfg_dev *fgdev, u16 reg, u32 value)
+{
+       iowrite32(value, fgdev->regs + reg);
+}
+
+/**** buffer management ****/
+
+/* program EC220 for transfer of a specific frame */
+static void setup_frame_transfer(struct b3dfg_dev *fgdev,
+       struct b3dfg_buffer *buf, int frame, int acknowledge)
+{
+       unsigned char *frm_addr;
+       dma_addr_t frm_addr_dma;
+       struct device *dev = &fgdev->pdev->dev;
+       unsigned int frame_size = fgdev->frame_size;
+       unsigned char dma_sts = 0xd;
+
+       frm_addr = buf->frame[frame];
+       frm_addr_dma = dma_map_single(dev, frm_addr, frame_size, DMA_FROM_DEVICE);
+       fgdev->cur_dma_frame_addr = frm_addr_dma;
+       fgdev->cur_dma_frame_idx = frame;
+
+       b3dfg_write32(fgdev, B3D_REG_EC220_DMA_ADDR, cpu_to_le32(frm_addr_dma));
+       b3dfg_write32(fgdev, B3D_REG_EC220_TRF_SIZE, cpu_to_le32(frame_size >> 2));
+
+       if (likely(acknowledge))
+               dma_sts |= 0x2;
+       b3dfg_write32(fgdev, B3D_REG_EC220_DMA_STS, 0xf);
+}
+
+/* retrieve a buffer pointer from a buffer index. also checks that the
+ * requested buffer actually exists. buffer_lock should be held by caller */
+static inline struct b3dfg_buffer *buffer_from_idx(struct b3dfg_dev *fgdev,
+       int idx)
+{
+       if (unlikely(idx >= fgdev->num_buffers))
+               return NULL;
+       return &fgdev->buffers[idx];
+}
+
+/* caller should hold buffer lock */
+static void free_all_buffers(struct b3dfg_dev *fgdev)
+{
+       kfree(fgdev->buffers);
+       fgdev->buffers = NULL;
+       fgdev->num_buffers = 0;
+}
+
+static void dequeue_all_buffers(struct b3dfg_dev *fgdev)
+{
+       int i;
+       for (i = 0; i < fgdev->num_buffers; i++) {
+               struct b3dfg_buffer *buf = &fgdev->buffers[i];
+               buf->state = B3DFG_BUFFER_POLLED;
+               list_del_init(&buf->list);
+       }
+}
+
+/* initialize a buffer: allocate its frames, set default values */
+static void init_buffer(struct b3dfg_dev *fgdev, struct b3dfg_buffer *buf,
+       int idx)
+{
+       unsigned int addr_offset = idx * B3DFG_FRAMES_PER_BUFFER;
+       int i;
+
+       memset(buf, 0, sizeof(struct b3dfg_buffer));
+       for (i = 0; i < B3DFG_FRAMES_PER_BUFFER; i++)
+               buf->frame[i] = fgdev->frame_buffer[addr_offset + i];
+
+       INIT_LIST_HEAD(&buf->list);
+}
+
+/* adjust the number of buffers, growing or shrinking the pool appropriately. */
+static int set_num_buffers(struct b3dfg_dev *fgdev, int num_buffers)
+{
+       int i;
+       struct b3dfg_buffer *buffers;
+       unsigned long flags;
+
+       printk(KERN_INFO PFX "set %d buffers\n", num_buffers);
+       if (fgdev->transmission_enabled) {
+               printk(KERN_ERR PFX
+                       "cannot set buffer count while transmission is enabled\n");
+               return -EBUSY;
+       }
+
+       if (atomic_read(&fgdev->mapping_count) > 0) {
+               printk(KERN_ERR PFX
+                       "cannot set buffer count while memory mappings are active\n");
+               return -EBUSY;
+       }
+
+       if (num_buffers > B3DFG_NR_TRIPLET_BUFFERS) {
+               printk(KERN_ERR PFX "limited to %d triplet buffers\n",
+                       B3DFG_NR_TRIPLET_BUFFERS);
+               return -E2BIG;
+       }
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       if (num_buffers == fgdev->num_buffers) {
+               spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+               return 0;
+       }
+
+       /* free all buffers then allocate new ones */
+       dequeue_all_buffers(fgdev);
+       free_all_buffers(fgdev);
+
+       /* must unlock to allocate GFP_KERNEL memory */
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+
+       if (num_buffers == 0)
+               return 0;
+
+       buffers = kmalloc(num_buffers * sizeof(struct b3dfg_buffer),
+               GFP_KERNEL);
+       if (!buffers)
+               return -ENOMEM;
+
+       for (i = 0; i < num_buffers; i++)
+               init_buffer(fgdev, &buffers[i], i);
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       fgdev->buffers = buffers;
+       fgdev->num_buffers = num_buffers;
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+
+       return 0;
+}
+
+/* queue a buffer to receive data */
+static int queue_buffer(struct b3dfg_dev *fgdev, int bufidx)
+{
+       struct b3dfg_buffer *buf;
+       unsigned long flags;
+       int r = 0;
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       buf = buffer_from_idx(fgdev, bufidx);
+       if (unlikely(!buf)) {
+               r = -ENOENT;
+               goto out;
+       }
+
+       if (unlikely(buf->state == B3DFG_BUFFER_PENDING)) {
+               printk(KERN_ERR PFX "buffer %d is already queued", bufidx);
+               r = -EINVAL;
+               goto out;
+       }
+
+       buf->state = B3DFG_BUFFER_PENDING;
+       list_add_tail(&buf->list, &fgdev->buffer_queue);
+
+       if (fgdev->transmission_enabled && fgdev->triplet_ready) {
+               dbg("triplet is ready, so pushing immediately\n");
+               fgdev->triplet_ready = 0;
+               setup_frame_transfer(fgdev, buf, 0, 0);
+       }
+
+out:
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+       return r;
+}
+
+/* non-blocking buffer poll. returns 1 if data is present in the buffer,
+ * 0 otherwise */
+static int poll_buffer(struct b3dfg_dev *fgdev, void __user *arg)
+{
+       struct b3dfg_poll p;
+       struct b3dfg_buffer *buf;
+       unsigned long flags;
+       int r = 1;
+
+       if (copy_from_user(&p, arg, sizeof(p)))
+               return -EFAULT;
+
+       if (unlikely(!fgdev->transmission_enabled)) {
+               printk(KERN_ERR PFX
+                       "cannot poll buffers when transmission is disabled\n");
+               return -EINVAL;
+       }
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       buf = buffer_from_idx(fgdev, p.buffer_idx);
+       if (unlikely(!buf)) {
+               r = -ENOENT;
+               goto out;
+       }
+
+       if (buf->state != B3DFG_BUFFER_POPULATED) {
+               r = 0;
+               goto out;
+       }
+
+       if (likely(buf->state == B3DFG_BUFFER_POPULATED)) {
+               buf->state = B3DFG_BUFFER_POLLED;
+               spin_lock(&fgdev->triplets_dropped_lock);
+               p.triplets_dropped = fgdev->triplets_dropped;
+               fgdev->triplets_dropped = 0;
+               spin_unlock(&fgdev->triplets_dropped_lock);
+               if (copy_to_user(arg, &p, sizeof(p)))
+                       r = -EFAULT;
+       }
+
+out:
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+       return r;
+}
+
+static u8 buffer_state(struct b3dfg_dev *fgdev, struct b3dfg_buffer *buf)
+{
+       unsigned long flags;
+       u8 state;
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       state = buf->state;
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+       return state;
+}
+
+/* sleep until a specific buffer becomes populated */
+static int wait_buffer(struct b3dfg_dev *fgdev, void __user *arg)
+{
+       struct b3dfg_wait w;
+       struct b3dfg_buffer *buf;
+       unsigned long flags;
+       int r;
+
+       if (copy_from_user(&w, arg, sizeof(w)))
+               return -EFAULT;
+
+       if (unlikely(!fgdev->transmission_enabled)) {
+               printk(KERN_ERR PFX
+                       "cannot wait on buffers when transmission is disabled\n");
+               return -EINVAL;
+       }
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       buf = buffer_from_idx(fgdev, w.buffer_idx);
+       if (unlikely(!buf)) {
+               r = -ENOENT;
+               goto out;
+       }
+
+       if (buf->state == B3DFG_BUFFER_POPULATED) {
+               r = 0;
+               goto out_triplets_dropped;
+       }
+
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+       /* FIXME: what prevents the buffer going away at this time? */
+
+       if (w.timeout > 0) {
+               r = wait_event_interruptible_timeout(fgdev->buffer_waitqueue,
+                       buffer_state(fgdev, buf) == B3DFG_BUFFER_POPULATED,
+                       (w.timeout * HZ) / 1000);
+               if (unlikely(r < 0))
+                       return r;
+               else if (unlikely(buffer_state(fgdev, buf)
+                               != B3DFG_BUFFER_POPULATED))
+                       return -ETIMEDOUT;
+               w.timeout = r * 1000 / HZ;
+       } else {
+               r = wait_event_interruptible(fgdev->buffer_waitqueue,
+                       buffer_state(fgdev, buf) == B3DFG_BUFFER_POPULATED);
+               if (unlikely(r))
+                       return -ERESTARTSYS;
+       }
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       /* FIXME: rediscover buffer? it might have changed during the unlocked
+        * time */
+       buf->state = B3DFG_BUFFER_POLLED;
+
+out_triplets_dropped:
+       spin_lock(&fgdev->triplets_dropped_lock);
+       w.triplets_dropped = fgdev->triplets_dropped;
+       fgdev->triplets_dropped = 0;
+       spin_unlock(&fgdev->triplets_dropped_lock);
+       if (copy_to_user(arg, &w, sizeof(w)))
+               r = -EFAULT;
+out:
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+       return r;
+}
+
+/**** virtual memory mapping ****/
+
+static void b3dfg_vma_open(struct vm_area_struct *vma)
+{
+       struct b3dfg_dev *fgdev = vma->vm_file->private_data;
+       atomic_inc(&fgdev->mapping_count);
+}
+
+static void b3dfg_vma_close(struct vm_area_struct *vma)
+{
+       struct b3dfg_dev *fgdev = vma->vm_file->private_data;
+       atomic_dec(&fgdev->mapping_count);
+}
+
+/* page fault handler */
+static unsigned long b3dfg_vma_nopfn(struct vm_area_struct *vma,
+       unsigned long address)
+{
+       struct b3dfg_dev *fgdev = vma->vm_file->private_data;
+       unsigned long off = address - vma->vm_start;
+       unsigned int frame_size = fgdev->frame_size;
+       unsigned int buf_size = frame_size * B3DFG_FRAMES_PER_BUFFER;
+       unsigned long flags;
+       unsigned char *addr;
+
+       /* determine which buffer the offset lies within */
+       unsigned int buf_idx = off / buf_size;
+       /* and the offset into the buffer */
+       unsigned int buf_off = off % buf_size;
+
+       /* determine which frame inside the buffer the offset lies in */
+       unsigned int frm_idx = buf_off / frame_size;
+       /* and the offset into the frame */
+       unsigned int frm_off = buf_off % frame_size;
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       if (unlikely(buf_idx > fgdev->num_buffers)) {
+               spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+               return NOPFN_SIGBUS;
+       }
+
+       addr = fgdev->buffers[buf_idx].frame[frm_idx] + frm_off;
+       vm_insert_pfn(vma, vma->vm_start + off,
+               virt_to_phys(addr) >> PAGE_SHIFT);
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+       return NOPFN_REFAULT;
+}
+
+static struct vm_operations_struct b3dfg_vm_ops = {
+       .open = b3dfg_vma_open,
+       .close = b3dfg_vma_close,
+       .nopfn = b3dfg_vma_nopfn,
+};
+
+static int get_wand_status(struct b3dfg_dev *fgdev, int __user *arg)
+{
+       u32 wndstat = b3dfg_read32(fgdev, B3D_REG_WAND_STS);
+       dbg("wand status %x\n", wndstat);
+       return __put_user(wndstat & 0x1, arg);
+}
+
+static int enable_transmission(struct b3dfg_dev *fgdev)
+{
+       u16 command;
+       unsigned long flags;
+
+       printk(KERN_INFO PFX "enable transmission\n");
+
+       /* check we're a bus master */
+       pci_read_config_word(fgdev->pdev, PCI_COMMAND, &command);
+       if (!(command & PCI_COMMAND_MASTER)) {
+               printk(KERN_ERR PFX "not a bus master, force-enabling\n");
+               /* FIXME: why did we lose it in the first place? */
+               pci_write_config_word(fgdev->pdev, PCI_COMMAND,
+                       command | PCI_COMMAND_MASTER);
+       }
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       if (fgdev->num_buffers == 0) {
+               spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+               printk(KERN_ERR PFX "cannot start transmission to 0 buffers\n");
+               return -EINVAL;
+       }
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+
+       spin_lock_irqsave(&fgdev->triplets_dropped_lock, flags);
+       fgdev->triplets_dropped = 0;
+       spin_unlock_irqrestore(&fgdev->triplets_dropped_lock, flags);
+
+       fgdev->triplet_ready = 0;
+       fgdev->transmission_enabled = 1;
+       fgdev->cur_dma_frame_idx = -1;
+       b3dfg_write32(fgdev, B3D_REG_HW_CTRL, 1);
+       return 0;
+}
+
+static void disable_transmission(struct b3dfg_dev *fgdev)
+{
+       unsigned long flags;
+       u32 tmp;
+
+       printk(KERN_INFO PFX "disable transmission\n");
+
+       /* guarantee that no more interrupts will be serviced */
+       fgdev->transmission_enabled = 0;
+       synchronize_irq(fgdev->pdev->irq);
+
+       b3dfg_write32(fgdev, B3D_REG_HW_CTRL, 0);
+
+       /* FIXME: temporary debugging only. if the board stops transmitting,
+        * hitting ctrl+c and seeing this message is useful for determining
+        * the state of the board. */
+       tmp = b3dfg_read32(fgdev, B3D_REG_DMA_STS);
+       dbg("brontes DMA_STS reads %x after TX stopped\n", tmp);
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       dequeue_all_buffers(fgdev);
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+}
+
+static int set_transmission(struct b3dfg_dev *fgdev, int enabled)
+{
+       if (enabled && !fgdev->transmission_enabled)
+               return enable_transmission(fgdev);
+       else if (!enabled && fgdev->transmission_enabled)
+               disable_transmission(fgdev);
+       return 0;
+}
+
+static irqreturn_t b3dfg_intr(int irq, void *dev_id)
+{
+       struct b3dfg_dev *fgdev = dev_id;
+       struct device *dev;
+       struct b3dfg_buffer *buf = NULL;
+       unsigned int frame_size;
+       u32 sts;
+       u8 dropped;
+       int next_trf;
+       int need_ack = 1;
+
+       if (unlikely(!fgdev->transmission_enabled)) {
+               printk("ignore interrupt, TX disabled\n");
+               /* FIXME should return IRQ_NONE when we are stable */
+               goto out;
+       }
+
+       sts = b3dfg_read32(fgdev, B3D_REG_DMA_STS);
+       if (unlikely(sts == 0)) {
+               printk("ignore interrupt, brontes DMA status is 0\n");
+               /* FIXME should return IRQ_NONE when we are stable */
+               goto out;
+       }
+
+       dropped = (sts >> 8) & 0xff;
+       dbg(KERN_INFO PFX "got intr, brontes DMASTS=%08x (dropped=%d comp=%d next_trf=%d)\n", sts, dropped, !!(sts & 0x4), sts & 0x3);
+
+       if (unlikely(dropped > 0)) {
+               spin_lock(&fgdev->triplets_dropped_lock);
+               fgdev->triplets_dropped += dropped;
+               spin_unlock(&fgdev->triplets_dropped_lock);
+       }
+
+       dev = &fgdev->pdev->dev;
+       frame_size = fgdev->frame_size;
+
+       spin_lock(&fgdev->buffer_lock);
+       if (unlikely(list_empty(&fgdev->buffer_queue))) {
+               /* FIXME need more sanity checking here */
+               dbg("driver has no buffer ready --> cannot program any more transfers\n");
+               fgdev->triplet_ready = 1;
+               goto out_unlock;
+       }
+
+       next_trf = sts & 0x3;
+
+       if (sts & 0x4) {
+               u32 tmp;
+
+               tmp = b3dfg_read32(fgdev, B3D_REG_EC220_DMA_STS);
+               /* last DMA completed */
+               if (unlikely(tmp & 0x1)) {
+                       printk(KERN_ERR PFX "EC220 reports error (%08x)\n", tmp);
+                       /* FIXME flesh out error handling */
+                       goto out_unlock;
+               }
+               if (unlikely(fgdev->cur_dma_frame_idx == -1)) {
+                       printk("ERROR completed but no last idx?\n");
+                       /* FIXME flesh out error handling */
+                       goto out_unlock;
+               }
+               dma_unmap_single(dev, fgdev->cur_dma_frame_addr, frame_size,
+                       DMA_FROM_DEVICE);
+
+               buf = list_entry(fgdev->buffer_queue.next, struct b3dfg_buffer, list);
+               if (likely(buf)) {
+                       dbg("handle frame completion\n");
+                       if (fgdev->cur_dma_frame_idx == B3DFG_FRAMES_PER_BUFFER - 1) {
+                               /* last frame of that triplet completed */
+                               dbg("triplet completed\n");
+                               buf->state = B3DFG_BUFFER_POPULATED;
+                               list_del_init(&buf->list);
+                               wake_up_interruptible(&fgdev->buffer_waitqueue);
+                       }
+               } else {
+                       printk("got frame but no buffer!\n");
+               }
+       }
+
+       if (next_trf) {
+               next_trf--;
+
+               buf = list_entry(fgdev->buffer_queue.next, struct b3dfg_buffer, list);
+               dbg("program DMA transfer for frame %d\n", next_trf + 1);
+               if (likely(buf)) {
+                       if (next_trf != fgdev->cur_dma_frame_idx + 1) {
+                               printk("ERROR mismatch, next_trf %d vs cur_dma_frame_idx %d\n",
+                                       next_trf, fgdev->cur_dma_frame_idx);
+                               /* FIXME this is where we should handle dropped triplets */
+                               goto out_unlock;
+                       }
+                       setup_frame_transfer(fgdev, buf, next_trf, 1);
+                       need_ack = 0;
+               } else {
+                       printk("cannot setup next DMA due to no buffer\n");
+               }
+       } else {
+               fgdev->cur_dma_frame_idx = -1;
+       }
+
+out_unlock:
+       spin_unlock(&fgdev->buffer_lock);
+out:
+       if (need_ack) {
+               dbg("acknowledging interrupt\n");
+               b3dfg_write32(fgdev, B3D_REG_EC220_DMA_STS, 0x0b);
+       }
+       return IRQ_HANDLED;
+}
+
+static int b3dfg_open(struct inode *inode, struct file *filp)
+{
+       struct b3dfg_dev *fgdev =
+               container_of(inode->i_cdev, struct b3dfg_dev, chardev);
+
+       printk(KERN_INFO PFX "open\n");
+       filp->private_data = fgdev;
+       return 0;
+}
+
+static int b3dfg_release(struct inode *inode, struct file *filp)
+{
+       struct b3dfg_dev *fgdev = filp->private_data;
+       printk(KERN_INFO PFX "release\n");
+       set_transmission(fgdev, 0);
+
+       /* no buffer locking needed, this is serialized */
+       dequeue_all_buffers(fgdev);
+       return set_num_buffers(fgdev, 0);
+}
+
+static long b3dfg_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+       struct b3dfg_dev *fgdev = filp->private_data;
+       int r;
+
+       switch (cmd) {
+       case B3DFG_IOCGFRMSZ:
+               return __put_user(fgdev->frame_size, (int __user *) arg);
+       case B3DFG_IOCGWANDSTAT:
+               return get_wand_status(fgdev, (int __user *) arg);
+       case B3DFG_IOCTNUMBUFS:
+               mutex_lock(&fgdev->ioctl_mutex);
+               r = set_num_buffers(fgdev, (int) arg);
+               mutex_unlock(&fgdev->ioctl_mutex);
+               return r;
+       case B3DFG_IOCTTRANS:
+               mutex_lock(&fgdev->ioctl_mutex);
+               r = set_transmission(fgdev, (int) arg);
+               mutex_unlock(&fgdev->ioctl_mutex);
+               return r;
+       case B3DFG_IOCTQUEUEBUF:
+               return queue_buffer(fgdev, (int) arg);
+       case B3DFG_IOCTPOLLBUF:
+               return poll_buffer(fgdev, (void __user *) arg);
+       case B3DFG_IOCTWAITBUF:
+               return wait_buffer(fgdev, (void __user *) arg);
+       default:
+               printk(KERN_ERR PFX "unrecognised ioctl %x\n", cmd);
+               return -EINVAL;
+       }
+}
+
+static unsigned int b3dfg_poll(struct file *filp, poll_table *poll_table)
+{
+       struct b3dfg_dev *fgdev = filp->private_data;
+       unsigned long flags;
+       int i;
+       int r = 0;
+
+       /* don't let the user mess with buffer allocations etc. while polling */
+       mutex_lock(&fgdev->ioctl_mutex);
+
+       if (unlikely(!fgdev->transmission_enabled)) {
+               printk(KERN_ERR PFX "cannot poll() when transmission is disabled\n");
+               r = POLLERR;
+               goto out;
+       }
+
+       poll_wait(filp, &fgdev->buffer_waitqueue, poll_table);
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       for (i = 0; i < fgdev->num_buffers; i++) {
+               if (fgdev->buffers[i].state == B3DFG_BUFFER_POPULATED) {
+                       r = POLLIN | POLLRDNORM;
+                       goto out_buffer_unlock;
+               }
+       }
+
+out_buffer_unlock:
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+out:
+       mutex_unlock(&fgdev->ioctl_mutex);
+       return r;
+}
+
+static int b3dfg_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+       struct b3dfg_dev *fgdev = filp->private_data;
+       unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
+       unsigned long vsize = vma->vm_end - vma->vm_start;
+       unsigned long bufdatalen;
+       unsigned long psize;
+       unsigned long flags;
+       int r = 0;
+
+       /* don't let user mess with buffer allocations during mmap */
+       mutex_lock(&fgdev->ioctl_mutex);
+
+       spin_lock_irqsave(&fgdev->buffer_lock, flags);
+       bufdatalen = fgdev->num_buffers * fgdev->frame_size * 3;
+       psize = bufdatalen - offset;
+
+       if (fgdev->num_buffers == 0) {
+               spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+               r = -ENOENT;
+               goto out;
+       }
+       spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+       if (vsize > psize) {
+               r = -EINVAL;
+               goto out;
+       }
+
+       vma->vm_flags |= VM_IO | VM_RESERVED | VM_CAN_NONLINEAR | VM_PFNMAP;
+       vma->vm_ops = &b3dfg_vm_ops;
+       b3dfg_vma_open(vma);
+
+out:
+       mutex_unlock(&fgdev->ioctl_mutex);
+       return r;
+}
+
+static struct file_operations b3dfg_fops = {
+       .owner = THIS_MODULE,
+       .open = b3dfg_open,
+       .release = b3dfg_release,
+       .unlocked_ioctl = b3dfg_ioctl,
+       .poll = b3dfg_poll,
+       .mmap = b3dfg_mmap,
+};
+
+static void free_all_frame_buffers(struct b3dfg_dev *fgdev)
+{
+       int i;
+       for (i = 0; i < B3DFG_NR_FRAME_BUFFERS; i++)
+               kfree(fgdev->frame_buffer[i]);
+}
+
+/* initialize device and any data structures. called before any interrupts
+ * are enabled. */
+static int b3dfg_init_dev(struct b3dfg_dev *fgdev)
+{
+       int i;
+       u32 frm_size = b3dfg_read32(fgdev, B3D_REG_FRM_SIZE);
+
+       /* disable interrupts. in abnormal circumstances (e.g. after a crash) the
+        * board may still be transmitting from the previous session. if we ensure
+        * that interrupts are disabled before we later enable them, we are sure
+        * to capture a triplet from the start, rather than starting from frame
+        * 2 or 3. disabling interrupts causes the FG to throw away all buffered
+        * data and stop buffering more until interrupts are enabled again. */
+       b3dfg_write32(fgdev, B3D_REG_HW_CTRL, 0);
+
+       fgdev->frame_size = frm_size * 4096;
+       for (i = 0; i < B3DFG_NR_FRAME_BUFFERS; i++) {
+               fgdev->frame_buffer[i] = kmalloc(fgdev->frame_size, GFP_KERNEL);
+               if (!fgdev->frame_buffer[i])
+                       goto err_no_mem;
+       }
+
+       INIT_LIST_HEAD(&fgdev->buffer_queue);
+       init_waitqueue_head(&fgdev->buffer_waitqueue);
+       spin_lock_init(&fgdev->buffer_lock);
+       spin_lock_init(&fgdev->triplets_dropped_lock);
+       atomic_set(&fgdev->mapping_count, 0);
+       mutex_init(&fgdev->ioctl_mutex);
+       return 0;
+
+err_no_mem:
+       free_all_frame_buffers(fgdev);
+       return -ENOMEM;
+}
+
+/* find next free minor number, returns -1 if none are availabile */
+static int get_free_minor(void)
+{
+       int i;
+       for (i = 0; i < B3DFG_MAX_DEVS; i++) {
+               if (b3dfg_devices[i] == 0)
+                       return i;
+       }
+       return -1;
+}
+
+static int __devinit b3dfg_probe(struct pci_dev *pdev,
+       const struct pci_device_id *id)
+{
+       struct b3dfg_dev *fgdev = kzalloc(sizeof(*fgdev), GFP_KERNEL);
+       int r = 0;
+       int minor = get_free_minor();
+       dev_t devno = MKDEV(MAJOR(b3dfg_devt), minor);
+
+       if (fgdev == NULL)
+               return -ENOMEM;
+
+       if (minor < 0) {
+               printk(KERN_ERR PFX "too many devices found!\n");
+               return -EIO;
+       }
+
+       b3dfg_devices[minor] = 1;
+       printk(KERN_INFO PFX "probe device at %s with IRQ %d\n",
+               pci_name(pdev), pdev->irq);
+
+       cdev_init(&fgdev->chardev, &b3dfg_fops);
+       fgdev->chardev.owner = THIS_MODULE;
+
+       r = cdev_add(&fgdev->chardev, devno, 1);
+       if (r)
+               goto err1;
+
+       fgdev->classdev = class_device_create(b3dfg_class, NULL, devno, &pdev->dev,
+               DRIVER_NAME "%d", minor);
+       if (IS_ERR(fgdev->classdev)) {
+               r = PTR_ERR(fgdev->classdev);
+               goto err2;
+       }
+
+       r = pci_enable_device(pdev);
+       if (r)
+               goto err3;
+
+       if (pci_resource_len(pdev, B3DFG_BAR_REGS) != B3DFG_REGS_LENGTH) {
+               printk(KERN_ERR PFX "invalid register resource size\n");
+               goto err4;
+       }
+
+       if (pci_resource_flags(pdev, B3DFG_BAR_REGS) != IORESOURCE_MEM) {
+               printk(KERN_ERR PFX "invalid resource flags");
+               goto err4;
+       }
+
+       fgdev->regs = ioremap_nocache(pci_resource_start(pdev, B3DFG_BAR_REGS),
+               B3DFG_REGS_LENGTH);
+       if (!fgdev->regs) {
+               printk(KERN_ERR PFX "regs ioremap failed\n");
+               goto err4;
+       }
+
+       fgdev->pdev = pdev;
+       pci_set_drvdata(pdev, fgdev);
+       r = b3dfg_init_dev(fgdev);
+       if (r < 0) {
+               printk(KERN_ERR PFX "failed to initalize device\n");
+               goto err5;
+       }
+
+       r = request_irq(pdev->irq, b3dfg_intr, IRQF_SHARED, DRIVER_NAME, fgdev);
+       if (r) {
+               printk(KERN_ERR PFX "couldn't request irq %d\n", pdev->irq);
+               goto err6;
+       }
+
+       return 0;
+
+err6:
+       free_all_frame_buffers(fgdev);
+err5:
+       iounmap(fgdev->regs);
+err4:
+       pci_disable_device(pdev);
+err3:
+       class_device_unregister(fgdev->classdev);
+err2:
+       cdev_del(&fgdev->chardev);
+err1:
+       kfree(fgdev);
+       if (minor >= 0)
+               b3dfg_devices[minor] = 0;
+       return r;
+}
+
+static void __devexit b3dfg_remove(struct pci_dev *pdev)
+{
+       struct b3dfg_dev *fgdev = pci_get_drvdata(pdev);
+       unsigned int minor = MINOR(fgdev->chardev.dev);
+
+       printk(KERN_INFO PFX "remove\n");
+
+       free_irq(pdev->irq, fgdev);
+       iounmap(fgdev->regs);
+       pci_disable_device(pdev);
+       class_device_unregister(fgdev->classdev);
+       cdev_del(&fgdev->chardev);
+       free_all_frame_buffers(fgdev);
+       kfree(fgdev);
+       b3dfg_devices[minor] = 0;
+}
+
+static struct pci_driver b3dfg_driver = {
+       .name = DRIVER_NAME,
+       .id_table = b3dfg_ids,
+       .probe = b3dfg_probe,
+       .remove = b3dfg_remove,
+};
+
+static int __init b3dfg_module_init(void)
+{
+       int r;
+
+       printk(KERN_INFO PFX "loaded\n");
+
+       b3dfg_class = class_create(THIS_MODULE, DRIVER_NAME);
+       if (IS_ERR(b3dfg_class))
+               return PTR_ERR(b3dfg_class);
+
+       r = alloc_chrdev_region(&b3dfg_devt, 0, B3DFG_MAX_DEVS, DRIVER_NAME);
+       if (r)
+               goto err1;
+
+       r = pci_register_driver(&b3dfg_driver);
+       if (r)
+               goto err2;
+
+       return r;
+
+err2:
+       unregister_chrdev_region(b3dfg_devt, B3DFG_MAX_DEVS);
+err1:
+       class_destroy(b3dfg_class);
+       return r;
+}
+
+static void __exit b3dfg_module_exit(void)
+{
+       printk(KERN_INFO PFX "unloaded\n");
+       pci_unregister_driver(&b3dfg_driver);
+       unregister_chrdev_region(b3dfg_devt, B3DFG_MAX_DEVS);
+       class_destroy(b3dfg_class);
+}
+
+module_init(b3dfg_module_init);
+module_exit(b3dfg_module_exit);
+MODULE_AUTHOR("Daniel Drake <ddrake@brontes3d.com>");
+MODULE_DESCRIPTION("Brontes frame grabber driver");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(pci, b3dfg_ids);
+