Merge branch 'perf/nmi' into perf/core

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / staging / udlfb / udlfb.c

/*
 * udlfb.c -- Framebuffer driver for DisplayLink USB controller
 *
 * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
 * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
 * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License v2. See the file COPYING in the main directory of this archive for
 * more details.
 *
 * Layout is based on skeletonfb by James Simmons and Geert Uytterhoeven,
 * usb-skeleton by GregKH.
 *
 * Device-specific portions based on information from Displaylink, with work
 * from Florian Echtler, Henrik Bjerregaard Pedersen, and others.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/usb.h>
#include <linux/uaccess.h>
#include <linux/mm.h>
#include <linux/fb.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>

#include "udlfb.h"

static struct fb_fix_screeninfo dlfb_fix = {
        .id =           "udlfb",
        .type =         FB_TYPE_PACKED_PIXELS,
        .visual =       FB_VISUAL_TRUECOLOR,
        .xpanstep =     0,
        .ypanstep =     0,
        .ywrapstep =    0,
        .accel =        FB_ACCEL_NONE,
};

static const u32 udlfb_info_flags = FBINFO_DEFAULT | FBINFO_READS_FAST |
#ifdef FBINFO_VIRTFB
                FBINFO_VIRTFB |
#endif
                FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_FILLRECT |
                FBINFO_HWACCEL_COPYAREA | FBINFO_MISC_ALWAYS_SETPAR;

/*
 * There are many DisplayLink-based products, all with unique PIDs. We are able
 * to support all volume ones (circa 2009) with a single driver, so we match
 * globally on VID. TODO: Probe() needs to detect when we might be running
 * "future" chips, and bail on those, so a compatible driver can match.
 */
static struct usb_device_id id_table[] = {
        {.idVendor = 0x17e9, .match_flags = USB_DEVICE_ID_MATCH_VENDOR,},
        {},
};
MODULE_DEVICE_TABLE(usb, id_table);

#ifndef CONFIG_FB_DEFERRED_IO
#warning Please set CONFIG_FB_DEFFERRED_IO option to support generic fbdev apps
#endif

#ifndef CONFIG_FB_SYS_IMAGEBLIT
#ifndef CONFIG_FB_SYS_IMAGEBLIT_MODULE
#warning Please set CONFIG_FB_SYS_IMAGEBLIT option to support fb console
#endif
#endif

#ifndef CONFIG_FB_MODE_HELPERS
#warning CONFIG_FB_MODE_HELPERS required. Expect build break
#endif

/* dlfb keeps a list of urbs for efficient bulk transfers */
static void dlfb_urb_completion(struct urb *urb);
static struct urb *dlfb_get_urb(struct dlfb_data *dev);
static int dlfb_submit_urb(struct dlfb_data *dev, struct urb * urb, size_t len);
static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size);
static void dlfb_free_urb_list(struct dlfb_data *dev);

/* other symbols with dependents */
#ifdef CONFIG_FB_DEFERRED_IO
static struct fb_deferred_io dlfb_defio;
#endif

/*
 * All DisplayLink bulk operations start with 0xAF, followed by specific code
 * All operations are written to buffers which then later get sent to device
 */
static char *dlfb_set_register(char *buf, u8 reg, u8 val)
{
        *buf++ = 0xAF;
        *buf++ = 0x20;
        *buf++ = reg;
        *buf++ = val;
        return buf;
}

static char *dlfb_vidreg_lock(char *buf)
{
        return dlfb_set_register(buf, 0xFF, 0x00);
}

static char *dlfb_vidreg_unlock(char *buf)
{
        return dlfb_set_register(buf, 0xFF, 0xFF);
}

/*
 * On/Off for driving the DisplayLink framebuffer to the display
 */
static char *dlfb_enable_hvsync(char *buf, bool enable)
{
        if (enable)
                return dlfb_set_register(buf, 0x1F, 0x00);
        else
                return dlfb_set_register(buf, 0x1F, 0x01);
}

static char *dlfb_set_color_depth(char *buf, u8 selection)
{
        return dlfb_set_register(buf, 0x00, selection);
}

static char *dlfb_set_base16bpp(char *wrptr, u32 base)
{
        /* the base pointer is 16 bits wide, 0x20 is hi byte. */
        wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
        wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
        return dlfb_set_register(wrptr, 0x22, base);
}

/*
 * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
 * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
 */
static char *dlfb_set_base8bpp(char *wrptr, u32 base)
{
        wrptr = dlfb_set_register(wrptr, 0x26, base >> 16);
        wrptr = dlfb_set_register(wrptr, 0x27, base >> 8);
        return dlfb_set_register(wrptr, 0x28, base);
}

static char *dlfb_set_register_16(char *wrptr, u8 reg, u16 value)
{
        wrptr = dlfb_set_register(wrptr, reg, value >> 8);
        return dlfb_set_register(wrptr, reg+1, value);
}

/*
 * This is kind of weird because the controller takes some
 * register values in a different byte order than other registers.
 */
static char *dlfb_set_register_16be(char *wrptr, u8 reg, u16 value)
{
        wrptr = dlfb_set_register(wrptr, reg, value);
        return dlfb_set_register(wrptr, reg+1, value >> 8);
}

/*
 * LFSR is linear feedback shift register. The reason we have this is
 * because the display controller needs to minimize the clock depth of
 * various counters used in the display path. So this code reverses the
 * provided value into the lfsr16 value by counting backwards to get
 * the value that needs to be set in the hardware comparator to get the
 * same actual count. This makes sense once you read above a couple of
 * times and think about it from a hardware perspective.
 */
static u16 dlfb_lfsr16(u16 actual_count)
{
        u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */

        while (actual_count--) {
                lv =     ((lv << 1) |
                        (((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
                        & 0xFFFF;
        }

        return (u16) lv;
}

/*
 * This does LFSR conversion on the value that is to be written.
 * See LFSR explanation above for more detail.
 */
static char *dlfb_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
{
        return dlfb_set_register_16(wrptr, reg, dlfb_lfsr16(value));
}

/*
 * This takes a standard fbdev screeninfo struct and all of its monitor mode
 * details and converts them into the DisplayLink equivalent register commands.
 */
static char *dlfb_set_vid_cmds(char *wrptr, struct fb_var_screeninfo *var)
{
        u16 xds, yds;
        u16 xde, yde;
        u16 yec;

        /* x display start */
        xds = var->left_margin + var->hsync_len;
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x01, xds);
        /* x display end */
        xde = xds + var->xres;
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x03, xde);

        /* y display start */
        yds = var->upper_margin + var->vsync_len;
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x05, yds);
        /* y display end */
        yde = yds + var->yres;
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x07, yde);

        /* x end count is active + blanking - 1 */
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x09,
                        xde + var->right_margin - 1);

        /* libdlo hardcodes hsync start to 1 */
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x0B, 1);

        /* hsync end is width of sync pulse + 1 */
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x0D, var->hsync_len + 1);

        /* hpixels is active pixels */
        wrptr = dlfb_set_register_16(wrptr, 0x0F, var->xres);

        /* yendcount is vertical active + vertical blanking */
        yec = var->yres + var->upper_margin + var->lower_margin +
                        var->vsync_len;
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x11, yec);

        /* libdlo hardcodes vsync start to 0 */
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x13, 0);

        /* vsync end is width of vsync pulse */
        wrptr = dlfb_set_register_lfsr16(wrptr, 0x15, var->vsync_len);

        /* vpixels is active pixels */
        wrptr = dlfb_set_register_16(wrptr, 0x17, var->yres);

        /* convert picoseconds to 5kHz multiple for pclk5k = x * 1E12/5k */
        wrptr = dlfb_set_register_16be(wrptr, 0x1B,
                        200*1000*1000/var->pixclock);

        return wrptr;
}

/*
 * This takes a standard fbdev screeninfo struct that was fetched or prepared
 * and then generates the appropriate command sequence that then drives the
 * display controller.
 */
static int dlfb_set_video_mode(struct dlfb_data *dev,
                                struct fb_var_screeninfo *var)
{
        char *buf;
        char *wrptr;
        int retval = 0;
        int writesize;
        struct urb *urb;

        if (!atomic_read(&dev->usb_active))
                return -EPERM;

        urb = dlfb_get_urb(dev);
        if (!urb)
                return -ENOMEM;
        buf = (char *) urb->transfer_buffer;

        /*
        * This first section has to do with setting the base address on the
        * controller * associated with the display. There are 2 base
        * pointers, currently, we only * use the 16 bpp segment.
        */
        wrptr = dlfb_vidreg_lock(buf);
        wrptr = dlfb_set_color_depth(wrptr, 0x00);
        /* set base for 16bpp segment to 0 */
        wrptr = dlfb_set_base16bpp(wrptr, 0);
        /* set base for 8bpp segment to end of fb */
        wrptr = dlfb_set_base8bpp(wrptr, dev->info->fix.smem_len);

        wrptr = dlfb_set_vid_cmds(wrptr, var);
        wrptr = dlfb_enable_hvsync(wrptr, true);
        wrptr = dlfb_vidreg_unlock(wrptr);

        writesize = wrptr - buf;

        retval = dlfb_submit_urb(dev, urb, writesize);

        return retval;
}

static int dlfb_ops_mmap(struct fb_info *info, struct vm_area_struct *vma)
{
        unsigned long start = vma->vm_start;
        unsigned long size = vma->vm_end - vma->vm_start;
        unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
        unsigned long page, pos;
        struct dlfb_data *dev = info->par;

        dl_notice("MMAP: %lu %u\n", offset + size, info->fix.smem_len);

        if (offset + size > info->fix.smem_len)
                return -EINVAL;

        pos = (unsigned long)info->fix.smem_start + offset;

        while (size > 0) {
                page = vmalloc_to_pfn((void *)pos);
                if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
                        return -EAGAIN;

                start += PAGE_SIZE;
                pos += PAGE_SIZE;
                if (size > PAGE_SIZE)
                        size -= PAGE_SIZE;
                else
                        size = 0;
        }

        vma->vm_flags |= VM_RESERVED;   /* avoid to swap out this VMA */
        return 0;

}

/*
 * Trims identical data from front and back of line
 * Sets new front buffer address and width
 * And returns byte count of identical pixels
 * Assumes CPU natural alignment (unsigned long)
 * for back and front buffer ptrs and width
 */
static int dlfb_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
{
        int j, k;
        const unsigned long *back = (const unsigned long *) bback;
        const unsigned long *front = (const unsigned long *) *bfront;
        const int width = *width_bytes / sizeof(unsigned long);
        int identical = width;
        int start = width;
        int end = width;

        prefetch((void *) front);
        prefetch((void *) back);

        for (j = 0; j < width; j++) {
                if (back[j] != front[j]) {
                        start = j;
                        break;
                }
        }

        for (k = width - 1; k > j; k--) {
                if (back[k] != front[k]) {
                        end = k+1;
                        break;
                }
        }

        identical = start + (width - end);
        *bfront = (u8 *) &front[start];
        *width_bytes = (end - start) * sizeof(unsigned long);

        return identical * sizeof(unsigned long);
}

/*
 * Render a command stream for an encoded horizontal line segment of pixels.
 *
 * A command buffer holds several commands.
 * It always begins with a fresh command header
 * (the protocol doesn't require this, but we enforce it to allow
 * multiple buffers to be potentially encoded and sent in parallel).
 * A single command encodes one contiguous horizontal line of pixels
 *
 * The function relies on the client to do all allocation, so that
 * rendering can be done directly to output buffers (e.g. USB URBs).
 * The function fills the supplied command buffer, providing information
 * on where it left off, so the client may call in again with additional
 * buffers if the line will take several buffers to complete.
 *
 * A single command can transmit a maximum of 256 pixels,
 * regardless of the compression ratio (protocol design limit).
 * To the hardware, 0 for a size byte means 256
 * 
 * Rather than 256 pixel commands which are either rl or raw encoded,
 * the rlx command simply assumes alternating raw and rl spans within one cmd.
 * This has a slightly larger header overhead, but produces more even results.
 * It also processes all data (read and write) in a single pass.
 * Performance benchmarks of common cases show it having just slightly better
 * compression than 256 pixel raw -or- rle commands, with similar CPU consumpion.
 * But for very rl friendly data, will compress not quite as well.
 */
static void dlfb_compress_hline(
        const uint16_t **pixel_start_ptr,
        const uint16_t *const pixel_end,
        uint32_t *device_address_ptr,
        uint8_t **command_buffer_ptr,
        const uint8_t *const cmd_buffer_end)
{
        const uint16_t *pixel = *pixel_start_ptr;
        uint32_t dev_addr  = *device_address_ptr;
        uint8_t *cmd = *command_buffer_ptr;
        const int bpp = 2;

        while ((pixel_end > pixel) &&
               (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
                uint8_t *raw_pixels_count_byte = 0;
                uint8_t *cmd_pixels_count_byte = 0;
                const uint16_t *raw_pixel_start = 0;
                const uint16_t *cmd_pixel_start, *cmd_pixel_end = 0;
                const uint32_t be_dev_addr = cpu_to_be32(dev_addr);

                prefetchw((void *) cmd); /* pull in one cache line at least */

                *cmd++ = 0xAF;
                *cmd++ = 0x6B;
                *cmd++ = (uint8_t) ((be_dev_addr >> 8) & 0xFF);
                *cmd++ = (uint8_t) ((be_dev_addr >> 16) & 0xFF);
                *cmd++ = (uint8_t) ((be_dev_addr >> 24) & 0xFF);

                cmd_pixels_count_byte = cmd++; /*  we'll know this later */
                cmd_pixel_start = pixel;

                raw_pixels_count_byte = cmd++; /*  we'll know this later */
                raw_pixel_start = pixel;

                cmd_pixel_end = pixel + min(MAX_CMD_PIXELS + 1,
                        min((int)(pixel_end - pixel),
                            (int)(cmd_buffer_end - cmd) / bpp));

                prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);

                while (pixel < cmd_pixel_end) {
                        const uint16_t * const repeating_pixel = pixel;

                        *(uint16_t *)cmd = cpu_to_be16p(pixel);
                        cmd += 2;
                        pixel++;

                        if (unlikely((pixel < cmd_pixel_end) &&
                                     (*pixel == *repeating_pixel))) {
                                /* go back and fill in raw pixel count */
                                *raw_pixels_count_byte = ((repeating_pixel -
                                                raw_pixel_start) + 1) & 0xFF;

                                while ((pixel < cmd_pixel_end)
                                       && (*pixel == *repeating_pixel)) {
                                        pixel++;
                                }

                                /* immediately after raw data is repeat byte */
                                *cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;

                                /* Then start another raw pixel span */
                                raw_pixel_start = pixel;
                                raw_pixels_count_byte = cmd++;
                        }
                }

                if (pixel > raw_pixel_start) {
                        /* finalize last RAW span */
                        *raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
                }

                *cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
                dev_addr += (pixel - cmd_pixel_start) * bpp;
        }

        if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
                /* Fill leftover bytes with no-ops */
                if (cmd_buffer_end > cmd)
                        memset(cmd, 0xAF, cmd_buffer_end - cmd);
                cmd = (uint8_t *) cmd_buffer_end;
        }

        *command_buffer_ptr = cmd;
        *pixel_start_ptr = pixel;
        *device_address_ptr = dev_addr;

        return;
}

/*
 * There are 3 copies of every pixel: The front buffer that the fbdev
 * client renders to, the actual framebuffer across the USB bus in hardware
 * (that we can only write to, slowly, and can never read), and (optionally)
 * our shadow copy that tracks what's been sent to that hardware buffer.
 */
static void dlfb_render_hline(struct dlfb_data *dev, struct urb **urb_ptr,
                              const char *front, char **urb_buf_ptr,
                              u32 byte_offset, u32 byte_width,
                              int *ident_ptr, int *sent_ptr)
{
        const u8 *line_start, *line_end, *next_pixel;
        u32 dev_addr = dev->base16 + byte_offset;
        struct urb *urb = *urb_ptr;
        u8 *cmd = *urb_buf_ptr;
        u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;

        line_start = (u8 *) (front + byte_offset);
        next_pixel = line_start;
        line_end = next_pixel + byte_width;

        if (dev->backing_buffer) {
                int offset;
                const u8 *back_start = (u8 *) (dev->backing_buffer
                                                + byte_offset);

                *ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
                        &byte_width);

                offset = next_pixel - line_start;
                line_end = next_pixel + byte_width;
                dev_addr += offset;
                back_start += offset;
                line_start += offset;

                memcpy((char *)back_start, (char *) line_start,
                       byte_width);
        }

        while (next_pixel < line_end) {

                dlfb_compress_hline((const uint16_t **) &next_pixel,
                             (const uint16_t *) line_end, &dev_addr,
                        (u8 **) &cmd, (u8 *) cmd_end);

                if (cmd >= cmd_end) {
                        int len = cmd - (u8 *) urb->transfer_buffer;
                        if (dlfb_submit_urb(dev, urb, len))
                                return; /* lost pixels is set */
                        *sent_ptr += len;
                        urb = dlfb_get_urb(dev);
                        if (!urb)
                                return; /* lost_pixels is set */
                        *urb_ptr = urb;
                        cmd = urb->transfer_buffer;
                        cmd_end = &cmd[urb->transfer_buffer_length];
                }
        }

        *urb_buf_ptr = cmd;
}

int dlfb_handle_damage(struct dlfb_data *dev, int x, int y,
               int width, int height, char *data)
{
        int i, ret;
        char *cmd;
        cycles_t start_cycles, end_cycles;
        int bytes_sent = 0;
        int bytes_identical = 0;
        struct urb *urb;
        int aligned_x;

        start_cycles = get_cycles();

        aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
        width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
        x = aligned_x;

        if ((width <= 0) ||
            (x + width > dev->info->var.xres) ||
            (y + height > dev->info->var.yres))
                return -EINVAL;

        if (!atomic_read(&dev->usb_active))
                return 0;

        urb = dlfb_get_urb(dev);
        if (!urb)
                return 0;
        cmd = urb->transfer_buffer;

        for (i = y; i < y + height ; i++) {
                const int line_offset = dev->info->fix.line_length * i;
                const int byte_offset = line_offset + (x * BPP);

                dlfb_render_hline(dev, &urb, (char *) dev->info->fix.smem_start,
                                  &cmd, byte_offset, width * BPP,
                                  &bytes_identical, &bytes_sent);
        }

        if (cmd > (char *) urb->transfer_buffer) {
                /* Send partial buffer remaining before exiting */
                int len = cmd - (char *) urb->transfer_buffer;
                ret = dlfb_submit_urb(dev, urb, len);
                bytes_sent += len;
        } else
                dlfb_urb_completion(urb);

        atomic_add(bytes_sent, &dev->bytes_sent);
        atomic_add(bytes_identical, &dev->bytes_identical);
        atomic_add(width*height*2, &dev->bytes_rendered);
        end_cycles = get_cycles();
        atomic_add(((unsigned int) ((end_cycles - start_cycles)
                    >> 10)), /* Kcycles */
                   &dev->cpu_kcycles_used);

        return 0;
}

/* hardware has native COPY command (see libdlo), but not worth it for fbcon */
static void dlfb_ops_copyarea(struct fb_info *info,
                                const struct fb_copyarea *area)
{

        struct dlfb_data *dev = info->par;

#if defined CONFIG_FB_SYS_COPYAREA || defined CONFIG_FB_SYS_COPYAREA_MODULE

        sys_copyarea(info, area);

        dlfb_handle_damage(dev, area->dx, area->dy,
                        area->width, area->height, info->screen_base);
#endif
        atomic_inc(&dev->copy_count);

}

static void dlfb_ops_imageblit(struct fb_info *info,
                                const struct fb_image *image)
{
        struct dlfb_data *dev = info->par;

#if defined CONFIG_FB_SYS_IMAGEBLIT || defined CONFIG_FB_SYS_IMAGEBLIT_MODULE

        sys_imageblit(info, image);

        dlfb_handle_damage(dev, image->dx, image->dy,
                        image->width, image->height, info->screen_base);

#endif

        atomic_inc(&dev->blit_count);
}

static void dlfb_ops_fillrect(struct fb_info *info,
                          const struct fb_fillrect *rect)
{
        struct dlfb_data *dev = info->par;

#if defined CONFIG_FB_SYS_FILLRECT || defined CONFIG_FB_SYS_FILLRECT_MODULE

        sys_fillrect(info, rect);

        dlfb_handle_damage(dev, rect->dx, rect->dy, rect->width,
                              rect->height, info->screen_base);
#endif

        atomic_inc(&dev->fill_count);

}

static void dlfb_get_edid(struct dlfb_data *dev)
{
        int i;
        int ret;
        char rbuf[2];

        for (i = 0; i < sizeof(dev->edid); i++) {
                ret = usb_control_msg(dev->udev,
                                    usb_rcvctrlpipe(dev->udev, 0), (0x02),
                                    (0x80 | (0x02 << 5)), i << 8, 0xA1, rbuf, 2,
                                    0);
                dev->edid[i] = rbuf[1];
        }
}

static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
                                unsigned long arg)
{

        struct dlfb_data *dev = info->par;
        struct dloarea *area = NULL;

        if (!atomic_read(&dev->usb_active))
                return 0;

        /* TODO: Update X server to get this from sysfs instead */
        if (cmd == DLFB_IOCTL_RETURN_EDID) {
                char *edid = (char *)arg;
                dlfb_get_edid(dev);
                if (copy_to_user(edid, dev->edid, sizeof(dev->edid)))
                        return -EFAULT;
                return 0;
        }

        /* TODO: Help propose a standard fb.h ioctl to report mmap damage */
        if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {

                area = (struct dloarea *)arg;

                if (area->x < 0)
                        area->x = 0;

                if (area->x > info->var.xres)
                        area->x = info->var.xres;

                if (area->y < 0)
                        area->y = 0;

                if (area->y > info->var.yres)
                        area->y = info->var.yres;

                atomic_set(&dev->use_defio, 0);

                dlfb_handle_damage(dev, area->x, area->y, area->w, area->h,
                           info->screen_base);
                atomic_inc(&dev->damage_count);
        }

        return 0;
}

/* taken from vesafb */
static int
dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
               unsigned blue, unsigned transp, struct fb_info *info)
{
        int err = 0;

        if (regno >= info->cmap.len)
                return 1;

        if (regno < 16) {
                if (info->var.red.offset == 10) {
                        /* 1:5:5:5 */
                        ((u32 *) (info->pseudo_palette))[regno] =
                            ((red & 0xf800) >> 1) |
                            ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
                } else {
                        /* 0:5:6:5 */
                        ((u32 *) (info->pseudo_palette))[regno] =
                            ((red & 0xf800)) |
                            ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
                }
        }

        return err;
}

/*
 * It's common for several clients to have framebuffer open simultaneously.
 * e.g. both fbcon and X. Makes things interesting.
 */
static int dlfb_ops_open(struct fb_info *info, int user)
{
        struct dlfb_data *dev = info->par;

/*      if (user == 0)
 *              We could special case kernel mode clients (fbcon) here
 */

        mutex_lock(&dev->fb_open_lock);

        dev->fb_count++;

#ifdef CONFIG_FB_DEFERRED_IO
        if ((atomic_read(&dev->use_defio)) && (info->fbdefio == NULL)) {
                /* enable defio */
                info->fbdefio = &dlfb_defio;
                fb_deferred_io_init(info);
        }
#endif

        dl_notice("open /dev/fb%d user=%d fb_info=%p count=%d\n",
            info->node, user, info, dev->fb_count);

        mutex_unlock(&dev->fb_open_lock);

        return 0;
}

static int dlfb_ops_release(struct fb_info *info, int user)
{
        struct dlfb_data *dev = info->par;

        mutex_lock(&dev->fb_open_lock);

        dev->fb_count--;

#ifdef CONFIG_FB_DEFERRED_IO
        if ((dev->fb_count == 0) && (info->fbdefio)) {
                fb_deferred_io_cleanup(info);
                info->fbdefio = NULL;
                info->fbops->fb_mmap = dlfb_ops_mmap;
        }
#endif

        dl_notice("release /dev/fb%d user=%d count=%d\n",
                  info->node, user, dev->fb_count);

        mutex_unlock(&dev->fb_open_lock);

        return 0;
}

/*
 * Called when all client interfaces to start transactions have been disabled,
 * and all references to our device instance (dlfb_data) are released.
 * Every transaction must have a reference, so we know are fully spun down
 */
static void dlfb_delete(struct kref *kref)
{
        struct dlfb_data *dev = container_of(kref, struct dlfb_data, kref);

        if (dev->backing_buffer)
                vfree(dev->backing_buffer);

        mutex_destroy(&dev->fb_open_lock);

        kfree(dev);
}

/*
 * Called by fbdev as last part of unregister_framebuffer() process
 * No new clients can open connections. Deallocate everything fb_info.
 */
static void dlfb_ops_destroy(struct fb_info *info)
{
        struct dlfb_data *dev = info->par;

        if (info->cmap.len != 0)
                fb_dealloc_cmap(&info->cmap);
        if (info->monspecs.modedb)
                fb_destroy_modedb(info->monspecs.modedb);
        if (info->screen_base)
                vfree(info->screen_base);

        fb_destroy_modelist(&info->modelist);

        framebuffer_release(info);

        /* ref taken before register_framebuffer() for dlfb_data clients */
        kref_put(&dev->kref, dlfb_delete);
}

/*
 * Check whether a video mode is supported by the DisplayLink chip
 * We start from monitor's modes, so don't need to filter that here
 */
static int dlfb_is_valid_mode(struct fb_videomode *mode,
                struct fb_info *info)
{
        struct dlfb_data *dev = info->par;

        if (mode->xres * mode->yres > dev->sku_pixel_limit)
                return 0;

        return 1;
}

static void dlfb_var_color_format(struct fb_var_screeninfo *var)
{
        const struct fb_bitfield red = { 11, 5, 0 };
        const struct fb_bitfield green = { 5, 6, 0 };
        const struct fb_bitfield blue = { 0, 5, 0 };

        var->bits_per_pixel = 16;
        var->red = red;
        var->green = green;
        var->blue = blue;
}

static int dlfb_ops_check_var(struct fb_var_screeninfo *var,
                                struct fb_info *info)
{
        struct fb_videomode mode;

        /* TODO: support dynamically changing framebuffer size */
        if ((var->xres * var->yres * 2) > info->fix.smem_len)
                return -EINVAL;

        /* set device-specific elements of var unrelated to mode */
        dlfb_var_color_format(var);

        fb_var_to_videomode(&mode, var);

        if (!dlfb_is_valid_mode(&mode, info))
                return -EINVAL;

        return 0;
}

static int dlfb_ops_set_par(struct fb_info *info)
{
        struct dlfb_data *dev = info->par;

        dl_notice("set_par mode %dx%d\n", info->var.xres, info->var.yres);

        return dlfb_set_video_mode(dev, &info->var);
}

static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
{
        struct dlfb_data *dev = info->par;
        char *bufptr;
        struct urb *urb;

        urb = dlfb_get_urb(dev);
        if (!urb)
                return 0;
        bufptr = (char *) urb->transfer_buffer;

        /* overloading usb_active.  UNBLANK can conflict with teardown */

        bufptr = dlfb_vidreg_lock(bufptr);
        if (blank_mode != FB_BLANK_UNBLANK) {
                atomic_set(&dev->usb_active, 0);
                bufptr = dlfb_enable_hvsync(bufptr, false);
        } else {
                atomic_set(&dev->usb_active, 1);
                bufptr = dlfb_enable_hvsync(bufptr, true);
        }
        bufptr = dlfb_vidreg_unlock(bufptr);

        dlfb_submit_urb(dev, urb, bufptr - (char *) urb->transfer_buffer);

        return 0;
}

static struct fb_ops dlfb_ops = {
        .owner = THIS_MODULE,
        .fb_setcolreg = dlfb_ops_setcolreg,
        .fb_fillrect = dlfb_ops_fillrect,
        .fb_copyarea = dlfb_ops_copyarea,
        .fb_imageblit = dlfb_ops_imageblit,
        .fb_mmap = dlfb_ops_mmap,
        .fb_ioctl = dlfb_ops_ioctl,
        .fb_open = dlfb_ops_open,
        .fb_release = dlfb_ops_release,
        .fb_blank = dlfb_ops_blank,
        .fb_check_var = dlfb_ops_check_var,
        .fb_set_par = dlfb_ops_set_par,
};

/*
 * Calls dlfb_get_edid() to query the EDID of attached monitor via usb cmds
 * Then parses EDID into three places used by various parts of fbdev:
 * fb_var_screeninfo contains the timing of the monitor's preferred mode
 * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
 * fb_info.modelist is a linked list of all monitor & VESA modes which work
 *
 * If EDID is not readable/valid, then modelist is all VESA modes,
 * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
 * Returns 0 if EDID parses successfully
 */
static int dlfb_parse_edid(struct dlfb_data *dev,
                            struct fb_var_screeninfo *var,
                            struct fb_info *info)
{
        int i;
        const struct fb_videomode *default_vmode = NULL;
        int result = 0;

        fb_destroy_modelist(&info->modelist);
        memset(&info->monspecs, 0, sizeof(info->monspecs));

        dlfb_get_edid(dev);
        fb_edid_to_monspecs(dev->edid, &info->monspecs);

        if (info->monspecs.modedb_len > 0) {

                for (i = 0; i < info->monspecs.modedb_len; i++) {
                        if (dlfb_is_valid_mode(&info->monspecs.modedb[i], info))
                                fb_add_videomode(&info->monspecs.modedb[i],
                                        &info->modelist);
                }

                default_vmode = fb_find_best_display(&info->monspecs,
                                                     &info->modelist);
        } else {
                struct fb_videomode fb_vmode = {0};

                dl_err("Unable to get valid EDID from device/display\n");
                result = 1;

                /*
                 * Add the standard VESA modes to our modelist
                 * Since we don't have EDID, there may be modes that
                 * overspec monitor and/or are incorrect aspect ratio, etc.
                 * But at least the user has a chance to choose
                 */
                for (i = 0; i < VESA_MODEDB_SIZE; i++) {
                        if (dlfb_is_valid_mode((struct fb_videomode *)
                                                &vesa_modes[i], info))
                                fb_add_videomode(&vesa_modes[i],
                                                 &info->modelist);
                }

                /*
                 * default to resolution safe for projectors
                 * (since they are most common case without EDID)
                 */
                fb_vmode.xres = 800;
                fb_vmode.yres = 600;
                fb_vmode.refresh = 60;
                default_vmode = fb_find_nearest_mode(&fb_vmode,
                                                     &info->modelist);
        }

        fb_videomode_to_var(var, default_vmode);
        dlfb_var_color_format(var);

        return result;
}

static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
                                   struct device_attribute *a, char *buf) {
        struct fb_info *fb_info = dev_get_drvdata(fbdev);
        struct dlfb_data *dev = fb_info->par;
        return snprintf(buf, PAGE_SIZE, "%u\n",
                        atomic_read(&dev->bytes_rendered));
}

static ssize_t metrics_bytes_identical_show(struct device *fbdev,
                                   struct device_attribute *a, char *buf) {
        struct fb_info *fb_info = dev_get_drvdata(fbdev);
        struct dlfb_data *dev = fb_info->par;
        return snprintf(buf, PAGE_SIZE, "%u\n",
                        atomic_read(&dev->bytes_identical));
}

static ssize_t metrics_bytes_sent_show(struct device *fbdev,
                                   struct device_attribute *a, char *buf) {
        struct fb_info *fb_info = dev_get_drvdata(fbdev);
        struct dlfb_data *dev = fb_info->par;
        return snprintf(buf, PAGE_SIZE, "%u\n",
                        atomic_read(&dev->bytes_sent));
}

static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
                                   struct device_attribute *a, char *buf) {
        struct fb_info *fb_info = dev_get_drvdata(fbdev);
        struct dlfb_data *dev = fb_info->par;
        return snprintf(buf, PAGE_SIZE, "%u\n",
                        atomic_read(&dev->cpu_kcycles_used));
}

static ssize_t metrics_misc_show(struct device *fbdev,
                                   struct device_attribute *a, char *buf) {
        struct fb_info *fb_info = dev_get_drvdata(fbdev);
        struct dlfb_data *dev = fb_info->par;
        return snprintf(buf, PAGE_SIZE,
                        "Calls to\ndamage: %u\nblit: %u\n"
                        "defio faults: %u\ncopy: %u\n"
                        "fill: %u\n\n"
                        "active framebuffer clients: %d\n"
                        "urbs available %d(%d)\n"
                        "Shadow framebuffer in use? %s\n"
                        "Any lost pixels? %s\n",
                        atomic_read(&dev->damage_count),
                        atomic_read(&dev->blit_count),
                        atomic_read(&dev->defio_fault_count),
                        atomic_read(&dev->copy_count),
                        atomic_read(&dev->fill_count),
                        dev->fb_count,
                        dev->urbs.available, dev->urbs.limit_sem.count,
                        (dev->backing_buffer) ? "yes" : "no",
                        atomic_read(&dev->lost_pixels) ? "yes" : "no");
}

static ssize_t edid_show(struct file *filp, struct kobject *kobj,
                         struct bin_attribute *a,
                         char *buf, loff_t off, size_t count) {
        struct device *fbdev = container_of(kobj, struct device, kobj);
        struct fb_info *fb_info = dev_get_drvdata(fbdev);
        struct dlfb_data *dev = fb_info->par;
        char *edid = &dev->edid[0];
        const size_t size = sizeof(dev->edid);

        if (dlfb_parse_edid(dev, &fb_info->var, fb_info))
                return 0;

        if (off >= size)
                return 0;

        if (off + count > size)
                count = size - off;
        memcpy(buf, edid + off, count);

        return count;
}


static ssize_t metrics_reset_store(struct device *fbdev,
                           struct device_attribute *attr,
                           const char *buf, size_t count)
{
        struct fb_info *fb_info = dev_get_drvdata(fbdev);
        struct dlfb_data *dev = fb_info->par;

        atomic_set(&dev->bytes_rendered, 0);
        atomic_set(&dev->bytes_identical, 0);
        atomic_set(&dev->bytes_sent, 0);
        atomic_set(&dev->cpu_kcycles_used, 0);
        atomic_set(&dev->blit_count, 0);
        atomic_set(&dev->copy_count, 0);
        atomic_set(&dev->fill_count, 0);
        atomic_set(&dev->defio_fault_count, 0);
        atomic_set(&dev->damage_count, 0);

        return count;
}

static ssize_t use_defio_show(struct device *fbdev,
                                   struct device_attribute *a, char *buf) {
        struct fb_info *fb_info = dev_get_drvdata(fbdev);
        struct dlfb_data *dev = fb_info->par;
        return snprintf(buf, PAGE_SIZE, "%d\n",
                        atomic_read(&dev->use_defio));
}

static ssize_t use_defio_store(struct device *fbdev,
                           struct device_attribute *attr,
                           const char *buf, size_t count)
{
        struct fb_info *fb_info = dev_get_drvdata(fbdev);
        struct dlfb_data *dev = fb_info->par;

        if (count > 0) {
                if (buf[0] == '0')
                        atomic_set(&dev->use_defio, 0);
                if (buf[0] == '1')
                        atomic_set(&dev->use_defio, 1);
        }
        return count;
}

static struct bin_attribute edid_attr = {
        .attr.name = "edid",
        .attr.mode = 0444,
        .size = 128,
        .read = edid_show,
};

static struct device_attribute fb_device_attrs[] = {
        __ATTR_RO(metrics_bytes_rendered),
        __ATTR_RO(metrics_bytes_identical),
        __ATTR_RO(metrics_bytes_sent),
        __ATTR_RO(metrics_cpu_kcycles_used),
        __ATTR_RO(metrics_misc),
        __ATTR(metrics_reset, S_IWUGO, NULL, metrics_reset_store),
        __ATTR_RW(use_defio),
};

#ifdef CONFIG_FB_DEFERRED_IO
static void dlfb_dpy_deferred_io(struct fb_info *info,
                                struct list_head *pagelist)
{
        struct page *cur;
        struct fb_deferred_io *fbdefio = info->fbdefio;
        struct dlfb_data *dev = info->par;
        struct urb *urb;
        char *cmd;
        cycles_t start_cycles, end_cycles;
        int bytes_sent = 0;
        int bytes_identical = 0;
        int bytes_rendered = 0;
        int fault_count = 0;

        if (!atomic_read(&dev->use_defio))
                return;

        if (!atomic_read(&dev->usb_active))
                return;

        start_cycles = get_cycles();

        urb = dlfb_get_urb(dev);
        if (!urb)
                return;
        cmd = urb->transfer_buffer;

        /* walk the written page list and render each to device */
        list_for_each_entry(cur, &fbdefio->pagelist, lru) {
                dlfb_render_hline(dev, &urb, (char *) info->fix.smem_start,
                                  &cmd, cur->index << PAGE_SHIFT,
                                  PAGE_SIZE, &bytes_identical, &bytes_sent);
                bytes_rendered += PAGE_SIZE;
                fault_count++;
        }

        if (cmd > (char *) urb->transfer_buffer) {
                /* Send partial buffer remaining before exiting */
                int len = cmd - (char *) urb->transfer_buffer;
                dlfb_submit_urb(dev, urb, len);
                bytes_sent += len;
        } else
                dlfb_urb_completion(urb);

        atomic_add(fault_count, &dev->defio_fault_count);
        atomic_add(bytes_sent, &dev->bytes_sent);
        atomic_add(bytes_identical, &dev->bytes_identical);
        atomic_add(bytes_rendered, &dev->bytes_rendered);
        end_cycles = get_cycles();
        atomic_add(((unsigned int) ((end_cycles - start_cycles)
                    >> 10)), /* Kcycles */
                   &dev->cpu_kcycles_used);
}

static struct fb_deferred_io dlfb_defio = {
        .delay          = 5,
        .deferred_io    = dlfb_dpy_deferred_io,
};

#endif

/*
 * This is necessary before we can communicate with the display controller.
 */
static int dlfb_select_std_channel(struct dlfb_data *dev)
{
        int ret;
        u8 set_def_chn[] = {       0x57, 0xCD, 0xDC, 0xA7,
                                0x1C, 0x88, 0x5E, 0x15,
                                0x60, 0xFE, 0xC6, 0x97,
                                0x16, 0x3D, 0x47, 0xF2  };

        ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
                        NR_USB_REQUEST_CHANNEL,
                        (USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
                        set_def_chn, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT);
        return ret;
}


static int dlfb_usb_probe(struct usb_interface *interface,
                        const struct usb_device_id *id)
{
        struct usb_device *usbdev;
        struct dlfb_data *dev;
        struct fb_info *info;
        int videomemorysize;
        int i;
        unsigned char *videomemory;
        int retval = -ENOMEM;
        struct fb_var_screeninfo *var;
        int registered = 0;
        u16 *pix_framebuffer;

        /* usb initialization */

        usbdev = interface_to_usbdev(interface);

        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (dev == NULL) {
                err("dlfb_usb_probe: failed alloc of dev struct\n");
                goto error;
        }

        /* we need to wait for both usb and fbdev to spin down on disconnect */
        kref_init(&dev->kref); /* matching kref_put in usb .disconnect fn */
        kref_get(&dev->kref); /* matching kref_put in .fb_destroy function*/

        dev->udev = usbdev;
        dev->gdev = &usbdev->dev; /* our generic struct device * */
        usb_set_intfdata(interface, dev);

        if (!dlfb_alloc_urb_list(dev, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
                retval = -ENOMEM;
                dl_err("dlfb_alloc_urb_list failed\n");
                goto error;
        }

        mutex_init(&dev->fb_open_lock);

        /* We don't register a new USB class. Our client interface is fbdev */

        /* allocates framebuffer driver structure, not framebuffer memory */
        info = framebuffer_alloc(0, &usbdev->dev);
        if (!info) {
                retval = -ENOMEM;
                dl_err("framebuffer_alloc failed\n");
                goto error;
        }
        dev->info = info;
        info->par = dev;
        info->pseudo_palette = dev->pseudo_palette;
        info->fbops = &dlfb_ops;

        var = &info->var;

        /* TODO set limit based on actual SKU detection */
        dev->sku_pixel_limit = 2048 * 1152;

        INIT_LIST_HEAD(&info->modelist);
        dlfb_parse_edid(dev, var, info);

        /*
         * ok, now that we've got the size info, we can alloc our framebuffer.
         */
        info->fix = dlfb_fix;
        info->fix.line_length = var->xres * (var->bits_per_pixel / 8);
        videomemorysize = info->fix.line_length * var->yres;

        /*
         * The big chunk of system memory we use as a virtual framebuffer.
         * TODO: Handle fbcon cursor code calling blit in interrupt context
         */
        videomemory = vmalloc(videomemorysize);
        if (!videomemory) {
                retval = -ENOMEM;
                dl_err("Virtual framebuffer alloc failed\n");
                goto error;
        }

        info->screen_base = videomemory;
        info->fix.smem_len = PAGE_ALIGN(videomemorysize);
        info->fix.smem_start = (unsigned long) videomemory;
        info->flags = udlfb_info_flags;


        /*
         * Second framebuffer copy, mirroring the state of the framebuffer
         * on the physical USB device. We can function without this.
         * But with imperfect damage info we may end up sending pixels over USB
         * that were, in fact, unchanged -- wasting limited USB bandwidth
         */
        dev->backing_buffer = vmalloc(videomemorysize);
        if (!dev->backing_buffer)
                dl_warn("No shadow/backing buffer allcoated\n");
        else
                memset(dev->backing_buffer, 0, videomemorysize);

        retval = fb_alloc_cmap(&info->cmap, 256, 0);
        if (retval < 0) {
                dl_err("fb_alloc_cmap failed %x\n", retval);
                goto error;
        }

        /* ready to begin using device */

#ifdef CONFIG_FB_DEFERRED_IO
        atomic_set(&dev->use_defio, 1);
#endif
        atomic_set(&dev->usb_active, 1);
        dlfb_select_std_channel(dev);

        dlfb_ops_check_var(var, info);
        dlfb_ops_set_par(info);

        /* paint greenscreen */
        pix_framebuffer = (u16 *) videomemory;
        for (i = 0; i < videomemorysize / 2; i++)
                pix_framebuffer[i] = 0x37e6;

        dlfb_handle_damage(dev, 0, 0, info->var.xres, info->var.yres,
                                videomemory);

        retval = register_framebuffer(info);
        if (retval < 0) {
                dl_err("register_framebuffer failed %d\n", retval);
                goto error;
        }
        registered = 1;

        for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
                device_create_file(info->dev, &fb_device_attrs[i]);

        device_create_bin_file(info->dev, &edid_attr);

        dl_err("DisplayLink USB device /dev/fb%d attached. %dx%d resolution."
                        " Using %dK framebuffer memory\n", info->node,
                        var->xres, var->yres,
                        ((dev->backing_buffer) ?
                        videomemorysize * 2 : videomemorysize) >> 10);
        return 0;

error:
        if (dev) {
                if (registered) {
                        unregister_framebuffer(info);
                        dlfb_ops_destroy(info);
                } else
                        kref_put(&dev->kref, dlfb_delete);

                if (dev->urbs.count > 0)
                        dlfb_free_urb_list(dev);
                kref_put(&dev->kref, dlfb_delete); /* last ref from kref_init */

                /* dev has been deallocated. Do not dereference */
        }

        return retval;
}

static void dlfb_usb_disconnect(struct usb_interface *interface)
{
        struct dlfb_data *dev;
        struct fb_info *info;
        int i;

        dev = usb_get_intfdata(interface);
        info = dev->info;

        /* when non-active we'll update virtual framebuffer, but no new urbs */
        atomic_set(&dev->usb_active, 0);

        usb_set_intfdata(interface, NULL);

        for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
                device_remove_file(info->dev, &fb_device_attrs[i]);

        device_remove_bin_file(info->dev, &edid_attr);

        /* this function will wait for all in-flight urbs to complete */
        dlfb_free_urb_list(dev);

        if (info) {
                dl_notice("Detaching /dev/fb%d\n", info->node);
                unregister_framebuffer(info);
                dlfb_ops_destroy(info);
        }

        /* release reference taken by kref_init in probe() */
        kref_put(&dev->kref, dlfb_delete);

        /* consider dlfb_data freed */

        return;
}

static struct usb_driver dlfb_driver = {
        .name = "udlfb",
        .probe = dlfb_usb_probe,
        .disconnect = dlfb_usb_disconnect,
        .id_table = id_table,
};

static int __init dlfb_module_init(void)
{
        int res;

        res = usb_register(&dlfb_driver);
        if (res)
                err("usb_register failed. Error number %d", res);

        printk(KERN_INFO "VMODES initialized\n");

        return res;
}

static void __exit dlfb_module_exit(void)
{
        usb_deregister(&dlfb_driver);
}

module_init(dlfb_module_init);
module_exit(dlfb_module_exit);

static void dlfb_urb_completion(struct urb *urb)
{
        struct urb_node *unode = urb->context;
        struct dlfb_data *dev = unode->dev;
        unsigned long flags;

        /* sync/async unlink faults aren't errors */
        if (urb->status) {
                if (!(urb->status == -ENOENT ||
                    urb->status == -ECONNRESET ||
                    urb->status == -ESHUTDOWN)) {
                        dl_err("%s - nonzero write bulk status received: %d\n",
                                __func__, urb->status);
                        atomic_set(&dev->lost_pixels, 1);
                }
        }

        urb->transfer_buffer_length = dev->urbs.size; /* reset to actual */

        spin_lock_irqsave(&dev->urbs.lock, flags);
        list_add_tail(&unode->entry, &dev->urbs.list);
        dev->urbs.available++;
        spin_unlock_irqrestore(&dev->urbs.lock, flags);

        up(&dev->urbs.limit_sem);
}

static void dlfb_free_urb_list(struct dlfb_data *dev)
{
        int count = dev->urbs.count;
        struct list_head *node;
        struct urb_node *unode;
        struct urb *urb;
        int ret;
        unsigned long flags;

        dl_notice("Waiting for completes and freeing all render urbs\n");

        /* keep waiting and freeing, until we've got 'em all */
        while (count--) {
                /* Timeout means a memory leak and/or fault */
                ret = down_timeout(&dev->urbs.limit_sem, FREE_URB_TIMEOUT);
                if (ret) {
                        BUG_ON(ret);
                        break;
                }
                spin_lock_irqsave(&dev->urbs.lock, flags);

                node = dev->urbs.list.next; /* have reserved one with sem */
                list_del_init(node);

                spin_unlock_irqrestore(&dev->urbs.lock, flags);

                unode = list_entry(node, struct urb_node, entry);
                urb = unode->urb;

                /* Free each separately allocated piece */
                usb_free_coherent(urb->dev, dev->urbs.size,
                                  urb->transfer_buffer, urb->transfer_dma);
                usb_free_urb(urb);
                kfree(node);
        }

        kref_put(&dev->kref, dlfb_delete);

}

static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size)
{
        int i = 0;
        struct urb *urb;
        struct urb_node *unode;
        char *buf;

        spin_lock_init(&dev->urbs.lock);

        dev->urbs.size = size;
        INIT_LIST_HEAD(&dev->urbs.list);

        while (i < count) {
                unode = kzalloc(sizeof(struct urb_node), GFP_KERNEL);
                if (!unode)
                        break;
                unode->dev = dev;

                urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!urb) {
                        kfree(unode);
                        break;
                }
                unode->urb = urb;

                buf = usb_alloc_coherent(dev->udev, MAX_TRANSFER, GFP_KERNEL,
                                         &urb->transfer_dma);
                if (!buf) {
                        kfree(unode);
                        usb_free_urb(urb);
                        break;
                }

                /* urb->transfer_buffer_length set to actual before submit */
                usb_fill_bulk_urb(urb, dev->udev, usb_sndbulkpipe(dev->udev, 1),
                        buf, size, dlfb_urb_completion, unode);
                urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

                list_add_tail(&unode->entry, &dev->urbs.list);

                i++;
        }

        sema_init(&dev->urbs.limit_sem, i);
        dev->urbs.count = i;
        dev->urbs.available = i;

        kref_get(&dev->kref); /* released in free_render_urbs() */

        dl_notice("allocated %d %d byte urbs\n", i, (int) size);

        return i;
}

static struct urb *dlfb_get_urb(struct dlfb_data *dev)
{
        int ret = 0;
        struct list_head *entry;
        struct urb_node *unode;
        struct urb *urb = NULL;
        unsigned long flags;

        /* Wait for an in-flight buffer to complete and get re-queued */
        ret = down_timeout(&dev->urbs.limit_sem, GET_URB_TIMEOUT);
        if (ret) {
                atomic_set(&dev->lost_pixels, 1);
                dl_err("wait for urb interrupted: %x\n", ret);
                goto error;
        }

        spin_lock_irqsave(&dev->urbs.lock, flags);

        BUG_ON(list_empty(&dev->urbs.list)); /* reserved one with limit_sem */
        entry = dev->urbs.list.next;
        list_del_init(entry);
        dev->urbs.available--;

        spin_unlock_irqrestore(&dev->urbs.lock, flags);

        unode = list_entry(entry, struct urb_node, entry);
        urb = unode->urb;

error:
        return urb;
}

static int dlfb_submit_urb(struct dlfb_data *dev, struct urb *urb, size_t len)
{
        int ret;

        BUG_ON(len > dev->urbs.size);

        urb->transfer_buffer_length = len; /* set to actual payload len */
        ret = usb_submit_urb(urb, GFP_KERNEL);
        if (ret) {
                dlfb_urb_completion(urb); /* because no one else will */
                atomic_set(&dev->lost_pixels, 1);
                dl_err("usb_submit_urb error %x\n", ret);
        }
        return ret;
}

MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
              "Jaya Kumar <jayakumar.lkml@gmail.com>, "
              "Bernie Thompson <bernie@plugable.com>");
MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
MODULE_LICENSE("GPL");