xen-fbfront.c

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/*
 * Xen para-virtual frame buffer device
 *
 * Copyright (C) 2005-2006 Anthony Liguori <[email protected]>
 * Copyright (C) 2006-2008 Red Hat, Inc., Markus Armbruster <[email protected]>
 *
 *  Based on linux/drivers/video/q40fb.c
 *
 *  This file is subject to the terms and conditions of the GNU General Public
 *  License. See the file COPYING in the main directory of this archive for
 *  more details.
 */

/*
 * TODO:
 *
 * Switch to grant tables when they become capable of dealing with the
 * frame buffer.
 */

#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fb.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>

#include <asm/xen/hypervisor.h>

#include <xen/xen.h>
#include <xen/events.h>
#include <xen/page.h>
#include <xen/interface/io/fbif.h>
#include <xen/interface/io/protocols.h>
#include <xen/xenbus.h>

struct xenfb_info {
    unsigned char       *fb;
    struct fb_info      *fb_info;
    int         x1, y1, x2, y2; /* dirty rectangle,
                           protected by dirty_lock */
    spinlock_t      dirty_lock;
    int         nr_pages;
    int         irq;
    struct xenfb_page   *page;
    unsigned long       *mfns;
    int         update_wanted; /* XENFB_TYPE_UPDATE wanted */
    int         feature_resize; /* XENFB_TYPE_RESIZE ok */
    struct xenfb_resize resize;     /* protected by resize_lock */
    int         resize_dpy; /* ditto */
    spinlock_t      resize_lock;

    struct xenbus_device    *xbdev;
};

#define XENFB_DEFAULT_FB_LEN (XENFB_WIDTH * XENFB_HEIGHT * XENFB_DEPTH / 8)

enum { KPARAM_MEM, KPARAM_WIDTH, KPARAM_HEIGHT, KPARAM_CNT };
static int video[KPARAM_CNT] = { 2, XENFB_WIDTH, XENFB_HEIGHT };
module_param_array(video, int, NULL, 0);
MODULE_PARM_DESC(video,
    "Video memory size in MB, width, height in pixels (default 2,800,600)");

static void xenfb_make_preferred_console(void);
static int xenfb_remove(struct xenbus_device *);
static void xenfb_init_shared_page(struct xenfb_info *, struct fb_info *);
static int xenfb_connect_backend(struct xenbus_device *, struct xenfb_info *);
static void xenfb_disconnect_backend(struct xenfb_info *);

static void xenfb_send_event(struct xenfb_info *info,
                 union xenfb_out_event *event)
{
    u32 prod;

    prod = info->page->out_prod;
    /* caller ensures !xenfb_queue_full() */
    mb();           /* ensure ring space available */
    XENFB_OUT_RING_REF(info->page, prod) = *event;
    wmb();          /* ensure ring contents visible */
    info->page->out_prod = prod + 1;

    notify_remote_via_irq(info->irq);
}

static void xenfb_do_update(struct xenfb_info *info,
                int x, int y, int w, int h)
{
    union xenfb_out_event event;

    memset(&event, 0, sizeof(event));
    event.type = XENFB_TYPE_UPDATE;
    event.update.x = x;
    event.update.y = y;
    event.update.width = w;
    event.update.height = h;

    /* caller ensures !xenfb_queue_full() */
    xenfb_send_event(info, &event);
}

static void xenfb_do_resize(struct xenfb_info *info)
{
    union xenfb_out_event event;

    memset(&event, 0, sizeof(event));
    event.resize = info->resize;

    /* caller ensures !xenfb_queue_full() */
    xenfb_send_event(info, &event);
}

static int xenfb_queue_full(struct xenfb_info *info)
{
    u32 cons, prod;

    prod = info->page->out_prod;
    cons = info->page->out_cons;
    return prod - cons == XENFB_OUT_RING_LEN;
}

static void xenfb_handle_resize_dpy(struct xenfb_info *info)
{
    unsigned long flags;

    spin_lock_irqsave(&info->resize_lock, flags);
    if (info->resize_dpy) {
        if (!xenfb_queue_full(info)) {
            info->resize_dpy = 0;
            xenfb_do_resize(info);
        }
    }
    spin_unlock_irqrestore(&info->resize_lock, flags);
}

static void xenfb_refresh(struct xenfb_info *info,
              int x1, int y1, int w, int h)
{
    unsigned long flags;
    int x2 = x1 + w - 1;
    int y2 = y1 + h - 1;

    xenfb_handle_resize_dpy(info);

    if (!info->update_wanted)
        return;

    spin_lock_irqsave(&info->dirty_lock, flags);

    /* Combine with dirty rectangle: */
    if (info->y1 < y1)
        y1 = info->y1;
    if (info->y2 > y2)
        y2 = info->y2;
    if (info->x1 < x1)
        x1 = info->x1;
    if (info->x2 > x2)
        x2 = info->x2;

    if (xenfb_queue_full(info)) {
        /* Can't send right now, stash it in the dirty rectangle */
        info->x1 = x1;
        info->x2 = x2;
        info->y1 = y1;
        info->y2 = y2;
        spin_unlock_irqrestore(&info->dirty_lock, flags);
        return;
    }

    /* Clear dirty rectangle: */
    info->x1 = info->y1 = INT_MAX;
    info->x2 = info->y2 = 0;

    spin_unlock_irqrestore(&info->dirty_lock, flags);

    if (x1 <= x2 && y1 <= y2)
        xenfb_do_update(info, x1, y1, x2 - x1 + 1, y2 - y1 + 1);
}

static void xenfb_deferred_io(struct fb_info *fb_info,
                  struct list_head *pagelist)
{
    struct xenfb_info *info = fb_info->par;
    struct page *page;
    unsigned long beg, end;
    int y1, y2, miny, maxy;

    miny = INT_MAX;
    maxy = 0;
    list_for_each_entry(page, pagelist, lru) {
        beg = page->index << PAGE_SHIFT;
        end = beg + PAGE_SIZE - 1;
        y1 = beg / fb_info->fix.line_length;
        y2 = end / fb_info->fix.line_length;
        if (y2 >= fb_info->var.yres)
            y2 = fb_info->var.yres - 1;
        if (miny > y1)
            miny = y1;
        if (maxy < y2)
            maxy = y2;
    }
    xenfb_refresh(info, 0, miny, fb_info->var.xres, maxy - miny + 1);
}

static struct fb_deferred_io xenfb_defio = {
    .delay      = HZ / 20,
    .deferred_io    = xenfb_deferred_io,
};

static int xenfb_setcolreg(unsigned regno, unsigned red, unsigned green,
               unsigned blue, unsigned transp,
               struct fb_info *info)
{
    u32 v;

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

#define CNVT_TOHW(val, width) ((((val)<<(width))+0x7FFF-(val))>>16)
    red = CNVT_TOHW(red, info->var.red.length);
    green = CNVT_TOHW(green, info->var.green.length);
    blue = CNVT_TOHW(blue, info->var.blue.length);
    transp = CNVT_TOHW(transp, info->var.transp.length);
#undef CNVT_TOHW

    v = (red << info->var.red.offset) |
        (green << info->var.green.offset) |
        (blue << info->var.blue.offset);

    switch (info->var.bits_per_pixel) {
    case 16:
    case 24:
    case 32:
        ((u32 *)info->pseudo_palette)[regno] = v;
        break;
    }

    return 0;
}

static void xenfb_fillrect(struct fb_info *p, const struct fb_fillrect *rect)
{
    struct xenfb_info *info = p->par;

    sys_fillrect(p, rect);
    xenfb_refresh(info, rect->dx, rect->dy, rect->width, rect->height);
}

static void xenfb_imageblit(struct fb_info *p, const struct fb_image *image)
{
    struct xenfb_info *info = p->par;

    sys_imageblit(p, image);
    xenfb_refresh(info, image->dx, image->dy, image->width, image->height);
}

static void xenfb_copyarea(struct fb_info *p, const struct fb_copyarea *area)
{
    struct xenfb_info *info = p->par;

    sys_copyarea(p, area);
    xenfb_refresh(info, area->dx, area->dy, area->width, area->height);
}

static ssize_t xenfb_write(struct fb_info *p, const char __user *buf,
            size_t count, loff_t *ppos)
{
    struct xenfb_info *info = p->par;
    ssize_t res;

    res = fb_sys_write(p, buf, count, ppos);
    xenfb_refresh(info, 0, 0, info->page->width, info->page->height);
    return res;
}

static int
xenfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
    struct xenfb_info *xenfb_info;
    int required_mem_len;

    xenfb_info = info->par;

    if (!xenfb_info->feature_resize) {
        if (var->xres == video[KPARAM_WIDTH] &&
            var->yres == video[KPARAM_HEIGHT] &&
            var->bits_per_pixel == xenfb_info->page->depth) {
            return 0;
        }
        return -EINVAL;
    }

    /* Can't resize past initial width and height */
    if (var->xres > video[KPARAM_WIDTH] || var->yres > video[KPARAM_HEIGHT])
        return -EINVAL;

    required_mem_len = var->xres * var->yres * xenfb_info->page->depth / 8;
    if (var->bits_per_pixel == xenfb_info->page->depth &&
        var->xres <= info->fix.line_length / (XENFB_DEPTH / 8) &&
        required_mem_len <= info->fix.smem_len) {
        var->xres_virtual = var->xres;
        var->yres_virtual = var->yres;
        return 0;
    }
    return -EINVAL;
}

static int xenfb_set_par(struct fb_info *info)
{
    struct xenfb_info *xenfb_info;
    unsigned long flags;

    xenfb_info = info->par;

    spin_lock_irqsave(&xenfb_info->resize_lock, flags);
    xenfb_info->resize.type = XENFB_TYPE_RESIZE;
    xenfb_info->resize.width = info->var.xres;
    xenfb_info->resize.height = info->var.yres;
    xenfb_info->resize.stride = info->fix.line_length;
    xenfb_info->resize.depth = info->var.bits_per_pixel;
    xenfb_info->resize.offset = 0;
    xenfb_info->resize_dpy = 1;
    spin_unlock_irqrestore(&xenfb_info->resize_lock, flags);
    return 0;
}

static struct fb_ops xenfb_fb_ops = {
    .owner      = THIS_MODULE,
    .fb_read    = fb_sys_read,
    .fb_write   = xenfb_write,
    .fb_setcolreg   = xenfb_setcolreg,
    .fb_fillrect    = xenfb_fillrect,
    .fb_copyarea    = xenfb_copyarea,
    .fb_imageblit   = xenfb_imageblit,
    .fb_check_var   = xenfb_check_var,
    .fb_set_par     = xenfb_set_par,
};

static irqreturn_t xenfb_event_handler(int rq, void *dev_id)
{
    /*
     * No in events recognized, simply ignore them all.
     * If you need to recognize some, see xen-kbdfront's
     * input_handler() for how to do that.
     */
    struct xenfb_info *info = dev_id;
    struct xenfb_page *page = info->page;

    if (page->in_cons != page->in_prod) {
        info->page->in_cons = info->page->in_prod;
        notify_remote_via_irq(info->irq);
    }

    /* Flush dirty rectangle: */
    xenfb_refresh(info, INT_MAX, INT_MAX, -INT_MAX, -INT_MAX);

    return IRQ_HANDLED;
}

static int __devinit xenfb_probe(struct xenbus_device *dev,
                 const struct xenbus_device_id *id)
{
    struct xenfb_info *info;
    struct fb_info *fb_info;
    int fb_size;
    int val;
    int ret = 0;

    info = kzalloc(sizeof(*info), GFP_KERNEL);
    if (info == NULL) {
        xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
        return -ENOMEM;
    }

    /* Limit kernel param videoram amount to what is in xenstore */
    if (xenbus_scanf(XBT_NIL, dev->otherend, "videoram", "%d", &val) == 1) {
        if (val < video[KPARAM_MEM])
            video[KPARAM_MEM] = val;
    }

    /* If requested res does not fit in available memory, use default */
    fb_size = video[KPARAM_MEM] * 1024 * 1024;
    if (video[KPARAM_WIDTH] * video[KPARAM_HEIGHT] * XENFB_DEPTH / 8
        > fb_size) {
        video[KPARAM_WIDTH] = XENFB_WIDTH;
        video[KPARAM_HEIGHT] = XENFB_HEIGHT;
        fb_size = XENFB_DEFAULT_FB_LEN;
    }

    dev_set_drvdata(&dev->dev, info);
    info->xbdev = dev;
    info->irq = -1;
    info->x1 = info->y1 = INT_MAX;
    spin_lock_init(&info->dirty_lock);
    spin_lock_init(&info->resize_lock);

    info->fb = vzalloc(fb_size);
    if (info->fb == NULL)
        goto error_nomem;

    info->nr_pages = (fb_size + PAGE_SIZE - 1) >> PAGE_SHIFT;

    info->mfns = vmalloc(sizeof(unsigned long) * info->nr_pages);
    if (!info->mfns)
        goto error_nomem;

    /* set up shared page */
    info->page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
    if (!info->page)
        goto error_nomem;

    /* abusing framebuffer_alloc() to allocate pseudo_palette */
    fb_info = framebuffer_alloc(sizeof(u32) * 256, NULL);
    if (fb_info == NULL)
        goto error_nomem;

    /* complete the abuse: */
    fb_info->pseudo_palette = fb_info->par;
    fb_info->par = info;

    fb_info->screen_base = info->fb;

    fb_info->fbops = &xenfb_fb_ops;
    fb_info->var.xres_virtual = fb_info->var.xres = video[KPARAM_WIDTH];
    fb_info->var.yres_virtual = fb_info->var.yres = video[KPARAM_HEIGHT];
    fb_info->var.bits_per_pixel = XENFB_DEPTH;

    fb_info->var.red = (struct fb_bitfield){16, 8, 0};
    fb_info->var.green = (struct fb_bitfield){8, 8, 0};
    fb_info->var.blue = (struct fb_bitfield){0, 8, 0};

    fb_info->var.activate = FB_ACTIVATE_NOW;
    fb_info->var.height = -1;
    fb_info->var.width = -1;
    fb_info->var.vmode = FB_VMODE_NONINTERLACED;

    fb_info->fix.visual = FB_VISUAL_TRUECOLOR;
    fb_info->fix.line_length = fb_info->var.xres * XENFB_DEPTH / 8;
    fb_info->fix.smem_start = 0;
    fb_info->fix.smem_len = fb_size;
    strcpy(fb_info->fix.id, "xen");
    fb_info->fix.type = FB_TYPE_PACKED_PIXELS;
    fb_info->fix.accel = FB_ACCEL_NONE;

    fb_info->flags = FBINFO_FLAG_DEFAULT | FBINFO_VIRTFB;

    ret = fb_alloc_cmap(&fb_info->cmap, 256, 0);
    if (ret < 0) {
        framebuffer_release(fb_info);
        xenbus_dev_fatal(dev, ret, "fb_alloc_cmap");
        goto error;
    }

    fb_info->fbdefio = &xenfb_defio;
    fb_deferred_io_init(fb_info);

    xenfb_init_shared_page(info, fb_info);

    ret = xenfb_connect_backend(dev, info);
    if (ret < 0) {
        xenbus_dev_fatal(dev, ret, "xenfb_connect_backend");
        goto error_fb;
    }

    ret = register_framebuffer(fb_info);
    if (ret) {
        xenbus_dev_fatal(dev, ret, "register_framebuffer");
        goto error_fb;
    }
    info->fb_info = fb_info;

    xenfb_make_preferred_console();
    return 0;

error_fb:
    fb_deferred_io_cleanup(fb_info);
    fb_dealloc_cmap(&fb_info->cmap);
    framebuffer_release(fb_info);
error_nomem:
    if (!ret) {
        ret = -ENOMEM;
        xenbus_dev_fatal(dev, ret, "allocating device memory");
    }
error:
    xenfb_remove(dev);
    return ret;
}

static __devinit void
xenfb_make_preferred_console(void)
{
    struct console *c;

    if (console_set_on_cmdline)
        return;

    console_lock();
    for_each_console(c) {
        if (!strcmp(c->name, "tty") && c->index == 0)
            break;
    }
    console_unlock();
    if (c) {
        unregister_console(c);
        c->flags |= CON_CONSDEV;
        c->flags &= ~CON_PRINTBUFFER; /* don't print again */
        register_console(c);
    }
}

static int xenfb_resume(struct xenbus_device *dev)
{
    struct xenfb_info *info = dev_get_drvdata(&dev->dev);

    xenfb_disconnect_backend(info);
    xenfb_init_shared_page(info, info->fb_info);
    return xenfb_connect_backend(dev, info);
}

static int xenfb_remove(struct xenbus_device *dev)
{
    struct xenfb_info *info = dev_get_drvdata(&dev->dev);

    xenfb_disconnect_backend(info);
    if (info->fb_info) {
        fb_deferred_io_cleanup(info->fb_info);
        unregister_framebuffer(info->fb_info);
        fb_dealloc_cmap(&info->fb_info->cmap);
        framebuffer_release(info->fb_info);
    }
    free_page((unsigned long)info->page);
    vfree(info->mfns);
    vfree(info->fb);
    kfree(info);

    return 0;
}

static unsigned long vmalloc_to_mfn(void *address)
{
    return pfn_to_mfn(vmalloc_to_pfn(address));
}

static void xenfb_init_shared_page(struct xenfb_info *info,
                   struct fb_info *fb_info)
{
    int i;
    int epd = PAGE_SIZE / sizeof(info->mfns[0]);

    for (i = 0; i < info->nr_pages; i++)
        info->mfns[i] = vmalloc_to_mfn(info->fb + i * PAGE_SIZE);

    for (i = 0; i * epd < info->nr_pages; i++)
        info->page->pd[i] = vmalloc_to_mfn(&info->mfns[i * epd]);

    info->page->width = fb_info->var.xres;
    info->page->height = fb_info->var.yres;
    info->page->depth = fb_info->var.bits_per_pixel;
    info->page->line_length = fb_info->fix.line_length;
    info->page->mem_length = fb_info->fix.smem_len;
    info->page->in_cons = info->page->in_prod = 0;
    info->page->out_cons = info->page->out_prod = 0;
}

static int xenfb_connect_backend(struct xenbus_device *dev,
                 struct xenfb_info *info)
{
    int ret, evtchn, irq;
    struct xenbus_transaction xbt;

    ret = xenbus_alloc_evtchn(dev, &evtchn);
    if (ret)
        return ret;
    irq = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler,
                    0, dev->devicetype, info);
    if (irq < 0) {
        xenbus_free_evtchn(dev, evtchn);
        xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler");
        return irq;
    }
 again:
    ret = xenbus_transaction_start(&xbt);
    if (ret) {
        xenbus_dev_fatal(dev, ret, "starting transaction");
        goto unbind_irq;
    }
    ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu",
                virt_to_mfn(info->page));
    if (ret)
        goto error_xenbus;
    ret = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
                evtchn);
    if (ret)
        goto error_xenbus;
    ret = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
                XEN_IO_PROTO_ABI_NATIVE);
    if (ret)
        goto error_xenbus;
    ret = xenbus_printf(xbt, dev->nodename, "feature-update", "1");
    if (ret)
        goto error_xenbus;
    ret = xenbus_transaction_end(xbt, 0);
    if (ret) {
        if (ret == -EAGAIN)
            goto again;
        xenbus_dev_fatal(dev, ret, "completing transaction");
        goto unbind_irq;
    }

    xenbus_switch_state(dev, XenbusStateInitialised);
    info->irq = irq;
    return 0;

 error_xenbus:
    xenbus_transaction_end(xbt, 1);
    xenbus_dev_fatal(dev, ret, "writing xenstore");
 unbind_irq:
    unbind_from_irqhandler(irq, info);
    return ret;
}

static void xenfb_disconnect_backend(struct xenfb_info *info)
{
    /* Prevent xenfb refresh */
    info->update_wanted = 0;
    if (info->irq >= 0)
        unbind_from_irqhandler(info->irq, info);
    info->irq = -1;
}

static void xenfb_backend_changed(struct xenbus_device *dev,
                  enum xenbus_state backend_state)
{
    struct xenfb_info *info = dev_get_drvdata(&dev->dev);
    int val;

    switch (backend_state) {
    case XenbusStateInitialising:
    case XenbusStateInitialised:
    case XenbusStateReconfiguring:
    case XenbusStateReconfigured:
    case XenbusStateUnknown:
        break;

    case XenbusStateInitWait:
InitWait:
        xenbus_switch_state(dev, XenbusStateConnected);
        break;

    case XenbusStateConnected:
        /*
         * Work around xenbus race condition: If backend goes
         * through InitWait to Connected fast enough, we can
         * get Connected twice here.
         */
        if (dev->state != XenbusStateConnected)
            goto InitWait; /* no InitWait seen yet, fudge it */

        if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
                 "request-update", "%d", &val) < 0)
            val = 0;
        if (val)
            info->update_wanted = 1;

        if (xenbus_scanf(XBT_NIL, dev->otherend,
                 "feature-resize", "%d", &val) < 0)
            val = 0;
        info->feature_resize = val;
        break;

    case XenbusStateClosed:
        if (dev->state == XenbusStateClosed)
            break;
        /* Missed the backend's CLOSING state -- fallthrough */
    case XenbusStateClosing:
        xenbus_frontend_closed(dev);
        break;
    }
}

static const struct xenbus_device_id xenfb_ids[] = {
    { "vfb" },
    { "" }
};

static DEFINE_XENBUS_DRIVER(xenfb, ,
    .probe = xenfb_probe,
    .remove = xenfb_remove,
    .resume = xenfb_resume,
    .otherend_changed = xenfb_backend_changed,
);

static int __init xenfb_init(void)
{
    if (!xen_pv_domain())
        return -ENODEV;

    /* Nothing to do if running in dom0. */
    if (xen_initial_domain())
        return -ENODEV;

    return xenbus_register_frontend(&xenfb_driver);
}

static void __exit xenfb_cleanup(void)
{
    xenbus_unregister_driver(&xenfb_driver);
}

module_init(xenfb_init);
module_exit(xenfb_cleanup);

MODULE_DESCRIPTION("Xen virtual framebuffer device frontend");
MODULE_LICENSE("GPL");
MODULE_ALIAS("xen:vfb");