Pulled in the multi frame buffer support from the Pi3 repo
authorJames Hughes <james.hughes@raspberrypi.org>
Thu, 14 Mar 2019 13:27:54 +0000 (13:27 +0000)
committerDom Cobley <popcornmix@gmail.com>
Mon, 19 Feb 2024 11:31:34 +0000 (11:31 +0000)
drivers/video/fbdev/bcm2708_fb.c

index 55c3d62..16b355e 100644 (file)
@@ -2,6 +2,7 @@
  *  linux/drivers/video/bcm2708_fb.c
  *
  * Copyright (C) 2010 Broadcom
+ * Copyright (C) 2018 Raspberry Pi (Trading) Ltd
  *
  * 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
@@ -13,6 +14,7 @@
  * Copyright 1999-2001 Jeff Garzik <jgarzik@pobox.com>
  *
  */
+
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
@@ -33,6 +35,7 @@
 #include <linux/io.h>
 #include <linux/dma-mapping.h>
 #include <soc/bcm2835/raspberrypi-firmware.h>
+#include <linux/mutex.h>
 
 //#define BCM2708_FB_DEBUG
 #define MODULE_NAME "bcm2708_fb"
@@ -79,64 +82,150 @@ struct bcm2708_fb_stats {
        u32 dma_irqs;
 };
 
+struct vc4_display_settings_t {
+       u32 display_num;
+       u32 width;
+       u32 height;
+       u32 depth;
+       u32 pitch;
+       u32 virtual_width;
+       u32 virtual_height;
+       u32 virtual_width_offset;
+       u32 virtual_height_offset;
+       unsigned long fb_bus_address;
+};
+
+struct bcm2708_fb_dev;
+
 struct bcm2708_fb {
        struct fb_info fb;
        struct platform_device *dev;
-       struct rpi_firmware *fw;
        u32 cmap[16];
        u32 gpu_cmap[256];
-       int dma_chan;
-       int dma_irq;
-       void __iomem *dma_chan_base;
-       void *cb_base;          /* DMA control blocks */
-       dma_addr_t cb_handle;
        struct dentry *debugfs_dir;
-       wait_queue_head_t dma_waitq;
-       struct bcm2708_fb_stats stats;
+       struct dentry *debugfs_subdir;
        unsigned long fb_bus_address;
-       bool disable_arm_alloc;
+       struct { u32 base, length; } gpu;
+       struct vc4_display_settings_t display_settings;
+       struct debugfs_regset32 screeninfo_regset;
+       struct bcm2708_fb_dev *fbdev;
        unsigned int image_size;
        dma_addr_t dma_addr;
        void *cpuaddr;
 };
 
+#define MAX_FRAMEBUFFERS 3
+
+struct bcm2708_fb_dev {
+       int firmware_supports_multifb;
+       /* Protects the DMA system from multiple FB access */
+       struct mutex dma_mutex;
+       int dma_chan;
+       int dma_irq;
+       void __iomem *dma_chan_base;
+       wait_queue_head_t dma_waitq;
+       bool disable_arm_alloc;
+       struct bcm2708_fb_stats dma_stats;
+       void *cb_base;  /* DMA control blocks */
+       dma_addr_t cb_handle;
+       int instance_count;
+       int num_displays;
+       struct rpi_firmware *fw;
+       struct bcm2708_fb displays[MAX_FRAMEBUFFERS];
+};
+
 #define to_bcm2708(info)       container_of(info, struct bcm2708_fb, fb)
 
 static void bcm2708_fb_debugfs_deinit(struct bcm2708_fb *fb)
 {
-       debugfs_remove_recursive(fb->debugfs_dir);
-       fb->debugfs_dir = NULL;
+       debugfs_remove_recursive(fb->debugfs_subdir);
+       fb->debugfs_subdir = NULL;
+
+       fb->fbdev->instance_count--;
+
+       if (!fb->fbdev->instance_count) {
+               debugfs_remove_recursive(fb->debugfs_dir);
+               fb->debugfs_dir = NULL;
+       }
 }
 
 static int bcm2708_fb_debugfs_init(struct bcm2708_fb *fb)
 {
+       char buf[3];
+       struct bcm2708_fb_dev *fbdev = fb->fbdev;
+
        static struct debugfs_reg32 stats_registers[] = {
-               {
-                       "dma_copies",
-                       offsetof(struct bcm2708_fb_stats, dma_copies)
-               },
-               {
-                       "dma_irqs",
-                       offsetof(struct bcm2708_fb_stats, dma_irqs)
-               },
+       {"dma_copies", offsetof(struct bcm2708_fb_stats, dma_copies)},
+       {"dma_irqs",   offsetof(struct bcm2708_fb_stats, dma_irqs)},
+       };
+
+       static struct debugfs_reg32 screeninfo[] = {
+       {"width",        offsetof(struct fb_var_screeninfo, xres)},
+       {"height",       offsetof(struct fb_var_screeninfo, yres)},
+       {"bpp",          offsetof(struct fb_var_screeninfo, bits_per_pixel)},
+       {"xres_virtual", offsetof(struct fb_var_screeninfo, xres_virtual)},
+       {"yres_virtual", offsetof(struct fb_var_screeninfo, yres_virtual)},
+       {"xoffset",      offsetof(struct fb_var_screeninfo, xoffset)},
+       {"yoffset",      offsetof(struct fb_var_screeninfo, yoffset)},
        };
 
-       fb->debugfs_dir = debugfs_create_dir(DRIVER_NAME, NULL);
+       fb->debugfs_dir = debugfs_lookup(DRIVER_NAME, NULL);
+
+       if (!fb->debugfs_dir)
+               fb->debugfs_dir = debugfs_create_dir(DRIVER_NAME, NULL);
+
        if (!fb->debugfs_dir) {
-               pr_warn("%s: could not create debugfs entry\n",
-                       __func__);
+               dev_warn(fb->fb.dev, "%s: could not create debugfs folder\n",
+                        __func__);
                return -EFAULT;
        }
 
-       fb->stats.regset.regs = stats_registers;
-       fb->stats.regset.nregs = ARRAY_SIZE(stats_registers);
-       fb->stats.regset.base = &fb->stats;
+       snprintf(buf, sizeof(buf), "%u", fb->display_settings.display_num);
+
+       fb->debugfs_subdir = debugfs_create_dir(buf, fb->debugfs_dir);
 
        debugfs_create_regset32("stats", 0444, fb->debugfs_dir,
                                &fb->stats.regset);
+
+       if (!fb->debugfs_subdir) {
+               dev_warn(fb->fb.dev, "%s: could not create debugfs entry %u\n",
+                        __func__, fb->display_settings.display_num);
+               return -EFAULT;
+       }
+
+       fbdev->dma_stats.regset.regs = stats_registers;
+       fbdev->dma_stats.regset.nregs = ARRAY_SIZE(stats_registers);
+       fbdev->dma_stats.regset.base = &fbdev->dma_stats;
+
+       debugfs_create_regset32("dma_stats", 0444, fb->debugfs_subdir,
+                               &fbdev->dma_stats.regset);
+
+       fb->screeninfo_regset.regs = screeninfo;
+       fb->screeninfo_regset.nregs = ARRAY_SIZE(screeninfo);
+       fb->screeninfo_regset.base = &fb->fb.var;
+
+       debugfs_create_regset32("screeninfo", 0444, fb->debugfs_subdir,
+                               &fb->screeninfo_regset);
+
+       fbdev->instance_count++;
+
        return 0;
 }
 
+static void set_display_num(struct bcm2708_fb *fb)
+{
+       if (fb && fb->fbdev && fb->fbdev->firmware_supports_multifb) {
+               u32 tmp = fb->display_settings.display_num;
+
+               if (rpi_firmware_property(fb->fbdev->fw,
+                                         RPI_FIRMWARE_FRAMEBUFFER_SET_DISPLAY_NUM,
+                                         &tmp,
+                                         sizeof(tmp)))
+                       dev_warn_once(fb->fb.dev,
+                                     "Set display number call failed. Old GPU firmware?");
+       }
+}
+
 static int bcm2708_fb_set_bitfields(struct fb_var_screeninfo *var)
 {
        int ret = 0;
@@ -214,11 +303,11 @@ static int bcm2708_fb_check_var(struct fb_var_screeninfo *var,
                                struct fb_info *info)
 {
        /* info input, var output */
-       print_debug("%s(%p) %dx%d (%dx%d), %d, %d\n",
+       print_debug("%s(%p) %ux%u (%ux%u), %ul, %u\n",
                    __func__, info, info->var.xres, info->var.yres,
                    info->var.xres_virtual, info->var.yres_virtual,
-                   (int)info->screen_size, info->var.bits_per_pixel);
-       print_debug("%s(%p) %dx%d (%dx%d), %d\n", __func__, var, var->xres,
+                   info->screen_size, info->var.bits_per_pixel);
+       print_debug("%s(%p) %ux%u (%ux%u), %u\n", __func__, var, var->xres,
                    var->yres, var->xres_virtual, var->yres_virtual,
                    var->bits_per_pixel);
 
@@ -281,17 +370,24 @@ static int bcm2708_fb_set_par(struct fb_info *info)
        };
        int ret, image_size;
 
-
-       print_debug("%s(%p) %dx%d (%dx%d), %d, %d\n", __func__, info,
+       print_debug("%s(%p) %dx%d (%dx%d), %d, %d (display %d)\n", __func__,
+                   info,
                    info->var.xres, info->var.yres, info->var.xres_virtual,
                    info->var.yres_virtual, (int)info->screen_size,
-                   info->var.bits_per_pixel);
+                   info->var.bits_per_pixel, value);
+
+       /* Need to set the display number to act on first
+        * Cannot do it in the tag list because on older firmware the call
+        * will fail and stop the rest of the list being executed.
+        * We can ignore this call failing as the default at other end is 0
+        */
+       set_display_num(fb);
 
        /* Try allocating our own buffer. We can specify all the parameters */
        image_size = ((info->var.xres * info->var.yres) *
                      info->var.bits_per_pixel) >> 3;
 
-       if (!fb->disable_arm_alloc &&
+       if (!fb->fbdev->disable_arm_alloc &&
            (image_size != fb->image_size || !fb->dma_addr)) {
                if (fb->dma_addr) {
                        dma_free_coherent(info->device, fb->image_size,
@@ -306,7 +402,7 @@ static int bcm2708_fb_set_par(struct fb_info *info)
 
                if (!fb->cpuaddr) {
                        fb->dma_addr = 0;
-                       fb->disable_arm_alloc = true;
+                       fb->fbdev->disable_arm_alloc = true;
                } else {
                        fb->image_size = image_size;
                }
@@ -317,7 +413,7 @@ static int bcm2708_fb_set_par(struct fb_info *info)
                fbinfo.screen_size = image_size;
                fbinfo.pitch = (info->var.xres * info->var.bits_per_pixel) >> 3;
 
-               ret = rpi_firmware_property_list(fb->fw, &fbinfo,
+               ret = rpi_firmware_property_list(fb->fbdev->fw, &fbinfo,
                                                 sizeof(fbinfo));
                if (ret || fbinfo.base != fb->dma_addr) {
                        /* Firmware either failed, or assigned a different base
@@ -330,7 +426,7 @@ static int bcm2708_fb_set_par(struct fb_info *info)
                        fb->image_size = 0;
                        fb->cpuaddr = NULL;
                        fb->dma_addr = 0;
-                       fb->disable_arm_alloc = true;
+                       fb->fbdev->disable_arm_alloc = true;
                }
        } else {
                /* Our allocation failed - drop into the old scheme of
@@ -349,7 +445,7 @@ static int bcm2708_fb_set_par(struct fb_info *info)
                fbinfo.tag6.tag = RPI_FIRMWARE_FRAMEBUFFER_GET_PITCH;
                fbinfo.pitch = 0;
 
-               ret = rpi_firmware_property_list(fb->fw, &fbinfo,
+               ret = rpi_firmware_property_list(fb->fbdev->fw, &fbinfo,
                                                 sizeof(fbinfo));
                if (ret) {
                        dev_err(info->device,
@@ -439,7 +535,10 @@ static int bcm2708_fb_setcolreg(unsigned int regno, unsigned int red,
                        packet->length = regno + 1;
                        memcpy(packet->cmap, fb->gpu_cmap,
                               sizeof(packet->cmap));
-                       ret = rpi_firmware_property(fb->fw,
+
+                       set_display_num(fb);
+
+                       ret = rpi_firmware_property(fb->fbdev->fw,
                                                    RPI_FIRMWARE_FRAMEBUFFER_SET_PALETTE,
                                                    packet,
                                                    (2 + packet->length) * sizeof(u32));
@@ -478,8 +577,11 @@ static int bcm2708_fb_blank(int blank_mode, struct fb_info *info)
                return -EINVAL;
        }
 
-       ret = rpi_firmware_property(fb->fw, RPI_FIRMWARE_FRAMEBUFFER_BLANK,
+       set_display_num(fb);
+
+       ret = rpi_firmware_property(fb->fbdev->fw, RPI_FIRMWARE_FRAMEBUFFER_BLANK,
                                    &value, sizeof(value));
+
        if (ret)
                dev_err(info->device, "%s(%d) failed: %d\n", __func__,
                        blank_mode, ret);
@@ -496,12 +598,14 @@ static int bcm2708_fb_pan_display(struct fb_var_screeninfo *var,
        info->var.yoffset = var->yoffset;
        result = bcm2708_fb_set_par(info);
        if (result != 0)
-               pr_err("%s(%d,%d) returns=%d\n", __func__, var->xoffset,
+               pr_err("%s(%u,%u) returns=%d\n", __func__, var->xoffset,
                       var->yoffset, result);
        return result;
 }
 
 static int bcm2708_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg)
+static int bcm2708_ioctl(struct fb_info *info, unsigned int cmd,
+                        unsigned long arg)
 {
        struct bcm2708_fb *fb = to_bcm2708(info);
        u32 dummy = 0;
@@ -509,7 +613,9 @@ static int bcm2708_ioctl(struct fb_info *info, unsigned int cmd, unsigned long a
 
        switch (cmd) {
        case FBIO_WAITFORVSYNC:
-               ret = rpi_firmware_property(fb->fw,
+               set_display_num(fb);
+
+               ret = rpi_firmware_property(fb->fbdev->fw,
                                            RPI_FIRMWARE_FRAMEBUFFER_SET_VSYNC,
                                            &dummy, sizeof(dummy));
                break;
@@ -526,23 +632,22 @@ static int bcm2708_ioctl(struct fb_info *info, unsigned int cmd, unsigned long a
 static void bcm2708_fb_fillrect(struct fb_info *info,
                                const struct fb_fillrect *rect)
 {
-       /* (is called) print_debug("bcm2708_fb_fillrect\n"); */
        cfb_fillrect(info, rect);
 }
 
 /* A helper function for configuring dma control block */
 static void set_dma_cb(struct bcm2708_dma_cb *cb,
-                      int        burst_size,
-                      dma_addr_t dst,
-                      int        dst_stride,
-                      dma_addr_t src,
-                      int        src_stride,
-                      int        w,
-                      int        h)
+               int        burst_size,
+               dma_addr_t dst,
+               int        dst_stride,
+               dma_addr_t src,
+               int        src_stride,
+               int        w,
+               int        h)
 {
        cb->info = BCM2708_DMA_BURST(burst_size) | BCM2708_DMA_S_WIDTH |
-                  BCM2708_DMA_S_INC | BCM2708_DMA_D_WIDTH |
-                  BCM2708_DMA_D_INC | BCM2708_DMA_TDMODE;
+               BCM2708_DMA_S_INC | BCM2708_DMA_D_WIDTH |
+               BCM2708_DMA_D_INC | BCM2708_DMA_TDMODE;
        cb->dst = dst;
        cb->src = src;
        /*
@@ -560,15 +665,19 @@ static void bcm2708_fb_copyarea(struct fb_info *info,
                                const struct fb_copyarea *region)
 {
        struct bcm2708_fb *fb = to_bcm2708(info);
-       struct bcm2708_dma_cb *cb = fb->cb_base;
+       struct bcm2708_fb_dev *fbdev = fb->fbdev;
+       struct bcm2708_dma_cb *cb = fbdev->cb_base;
        int bytes_per_pixel = (info->var.bits_per_pixel + 7) >> 3;
 
        /* Channel 0 supports larger bursts and is a bit faster */
-       int burst_size = (fb->dma_chan == 0) ? 8 : 2;
+       int burst_size = (fbdev->dma_chan == 0) ? 8 : 2;
        int pixels = region->width * region->height;
 
-       /* Fallback to cfb_copyarea() if we don't like something */
-       if (bytes_per_pixel > 4 ||
+       /* If DMA is currently in use (ie being used on another FB), then
+        * rather than wait for it to finish, just use the cfb_copyarea
+        */
+       if (!mutex_trylock(&fbdev->dma_mutex) ||
+           bytes_per_pixel > 4 ||
            info->var.xres * info->var.yres > 1920 * 1200 ||
            region->width <= 0 || region->width > info->var.xres ||
            region->height <= 0 || region->height > info->var.yres ||
@@ -595,8 +704,8 @@ static void bcm2708_fb_copyarea(struct fb_info *info,
                 * 1920x1200 resolution at 32bpp pixel depth.
                 */
                int y;
-               dma_addr_t control_block_pa = fb->cb_handle;
-               dma_addr_t scratchbuf = fb->cb_handle + 16 * 1024;
+               dma_addr_t control_block_pa = fbdev->cb_handle;
+               dma_addr_t scratchbuf = fbdev->cb_handle + 16 * 1024;
                int scanline_size = bytes_per_pixel * region->width;
                int scanlines_per_cb = (64 * 1024 - 16 * 1024) / scanline_size;
 
@@ -646,10 +755,10 @@ static void bcm2708_fb_copyarea(struct fb_info *info,
                }
                set_dma_cb(cb, burst_size,
                           fb->fb_bus_address + dy * fb->fb.fix.line_length +
-                                                  bytes_per_pixel * region->dx,
+                          bytes_per_pixel * region->dx,
                           stride,
                           fb->fb_bus_address + sy * fb->fb.fix.line_length +
-                                                  bytes_per_pixel * region->sx,
+                          bytes_per_pixel * region->sx,
                           stride,
                           region->width * bytes_per_pixel,
                           region->height);
@@ -659,32 +768,33 @@ static void bcm2708_fb_copyarea(struct fb_info *info,
        cb->next = 0;
 
        if (pixels < dma_busy_wait_threshold) {
-               bcm_dma_start(fb->dma_chan_base, fb->cb_handle);
-               bcm_dma_wait_idle(fb->dma_chan_base);
+               bcm_dma_start(fbdev->dma_chan_base, fbdev->cb_handle);
+               bcm_dma_wait_idle(fbdev->dma_chan_base);
        } else {
-               void __iomem *dma_chan = fb->dma_chan_base;
+               void __iomem *local_dma_chan = fbdev->dma_chan_base;
 
                cb->info |= BCM2708_DMA_INT_EN;
-               bcm_dma_start(fb->dma_chan_base, fb->cb_handle);
-               while (bcm_dma_is_busy(dma_chan)) {
-                       wait_event_interruptible(fb->dma_waitq,
-                                                !bcm_dma_is_busy(dma_chan));
+               bcm_dma_start(fbdev->dma_chan_base, fbdev->cb_handle);
+               while (bcm_dma_is_busy(local_dma_chan)) {
+                       wait_event_interruptible(fbdev->dma_waitq,
+                                                !bcm_dma_is_busy(local_dma_chan));
                }
-               fb->stats.dma_irqs++;
+               fbdev->dma_stats.dma_irqs++;
        }
-       fb->stats.dma_copies++;
+       fbdev->dma_stats.dma_copies++;
+
+       mutex_unlock(&fbdev->dma_mutex);
 }
 
 static void bcm2708_fb_imageblit(struct fb_info *info,
                                 const struct fb_image *image)
 {
-       /* (is called) print_debug("bcm2708_fb_imageblit\n"); */
        cfb_imageblit(info, image);
 }
 
 static irqreturn_t bcm2708_fb_dma_irq(int irq, void *cxt)
 {
-       struct bcm2708_fb *fb = cxt;
+       struct bcm2708_fb_dev *fbdev = cxt;
 
        /* FIXME: should read status register to check if this is
         * actually interrupting us or not, in case this interrupt
@@ -694,9 +804,9 @@ static irqreturn_t bcm2708_fb_dma_irq(int irq, void *cxt)
         */
 
        /* acknowledge the interrupt */
-       writel(BCM2708_DMA_INT, fb->dma_chan_base + BCM2708_DMA_CS);
+       writel(BCM2708_DMA_INT, fbdev->dma_chan_base + BCM2708_DMA_CS);
 
-       wake_up(&fb->dma_waitq);
+       wake_up(&fbdev->dma_waitq);
        return IRQ_HANDLED;
 }
 
@@ -729,11 +839,23 @@ static int bcm2708_fb_register(struct bcm2708_fb *fb)
        fb->fb.fix.ywrapstep = 0;
        fb->fb.fix.accel = FB_ACCEL_NONE;
 
-       fb->fb.var.xres = fbwidth;
-       fb->fb.var.yres = fbheight;
-       fb->fb.var.xres_virtual = fbwidth;
-       fb->fb.var.yres_virtual = fbheight;
-       fb->fb.var.bits_per_pixel = fbdepth;
+       /* If we have data from the VC4 on FB's, use that, otherwise use the
+        * module parameters
+        */
+       if (fb->display_settings.width) {
+               fb->fb.var.xres = fb->display_settings.width;
+               fb->fb.var.yres = fb->display_settings.height;
+               fb->fb.var.xres_virtual = fb->fb.var.xres;
+               fb->fb.var.yres_virtual = fb->fb.var.yres;
+               fb->fb.var.bits_per_pixel = fb->display_settings.depth;
+       } else {
+               fb->fb.var.xres = fbwidth;
+               fb->fb.var.yres = fbheight;
+               fb->fb.var.xres_virtual = fbwidth;
+               fb->fb.var.yres_virtual = fbheight;
+               fb->fb.var.bits_per_pixel = fbdepth;
+       }
+
        fb->fb.var.vmode = FB_VMODE_NONINTERLACED;
        fb->fb.var.activate = FB_ACTIVATE_NOW;
        fb->fb.var.nonstd = 0;
@@ -749,26 +871,23 @@ static int bcm2708_fb_register(struct bcm2708_fb *fb)
        fb->fb.monspecs.dclkmax = 100000000;
 
        bcm2708_fb_set_bitfields(&fb->fb.var);
-       init_waitqueue_head(&fb->dma_waitq);
 
        /*
         * Allocate colourmap.
         */
-
        fb_set_var(&fb->fb, &fb->fb.var);
+
        ret = bcm2708_fb_set_par(&fb->fb);
+
        if (ret)
                return ret;
 
-       print_debug("BCM2708FB: registering framebuffer (%dx%d@%d) (%d)\n",
-                   fbwidth, fbheight, fbdepth, fbswap);
-
        ret = register_framebuffer(&fb->fb);
-       print_debug("BCM2708FB: register framebuffer (%d)\n", ret);
+
        if (ret == 0)
                goto out;
 
-       print_debug("BCM2708FB: cannot register framebuffer (%d)\n", ret);
+       dev_warn(fb->fb.dev, "Unable to register framebuffer (%d)\n", ret);
 out:
        return ret;
 }
@@ -777,10 +896,18 @@ static int bcm2708_fb_probe(struct platform_device *dev)
 {
        struct device_node *fw_np;
        struct rpi_firmware *fw;
-       struct bcm2708_fb *fb;
-       int ret;
+       int ret, i;
+       u32 num_displays;
+       struct bcm2708_fb_dev *fbdev;
+       struct { u32 base, length; } gpu_mem;
+
+       fbdev = devm_kzalloc(&dev->dev, sizeof(*fbdev), GFP_KERNEL);
+
+       if (!fbdev)
+               return -ENOMEM;
 
        fw_np = of_parse_phandle(dev->dev.of_node, "firmware", 0);
+
 /* Remove comment when booting without Device Tree is no longer supported
  *     if (!fw_np) {
  *             dev_err(&dev->dev, "Missing firmware node\n");
@@ -788,90 +915,154 @@ static int bcm2708_fb_probe(struct platform_device *dev)
  *     }
  */
        fw = rpi_firmware_get(fw_np);
+       fbdev->fw = fw;
+
        if (!fw)
                return -EPROBE_DEFER;
 
-       fb = kzalloc(sizeof(*fb), GFP_KERNEL);
-       if (!fb) {
-               ret = -ENOMEM;
-               goto free_region;
+       ret = rpi_firmware_property(fw,
+                                   RPI_FIRMWARE_FRAMEBUFFER_GET_NUM_DISPLAYS,
+                                   &num_displays, sizeof(u32));
+
+       /* If we fail to get the number of displays, or it returns 0, then
+        * assume old firmware that doesn't have the mailbox call, so just
+        * set one display
+        */
+       if (ret || num_displays == 0) {
+               num_displays = 1;
+               dev_err(&dev->dev,
+                       "Unable to determine number of FB's. Assuming 1\n");
+               ret = 0;
+       } else {
+               fbdev->firmware_supports_multifb = 1;
        }
 
-       fb->fw = fw;
-       bcm2708_fb_debugfs_init(fb);
+       if (num_displays > MAX_FRAMEBUFFERS) {
+               dev_warn(&dev->dev,
+                        "More displays reported from firmware than supported in driver (%u vs %u)",
+                        num_displays, MAX_FRAMEBUFFERS);
+               num_displays = MAX_FRAMEBUFFERS;
+       }
 
-       fb->cb_base = dma_alloc_wc(&dev->dev, SZ_64K,
-                                            &fb->cb_handle, GFP_KERNEL);
-       if (!fb->cb_base) {
+       dev_info(&dev->dev, "FB found %d display(s)\n", num_displays);
+
+       /* Set up the DMA information. Note we have just one set of DMA
+        * parameters to work with all the FB's so requires synchronising when
+        * being used
+        */
+
+       mutex_init(&fbdev->dma_mutex);
+
+       fbdev->cb_base = dma_alloc_wc(&dev->dev, SZ_64K,
+                                               &fbdev->cb_handle,
+                                               GFP_KERNEL);
+       if (!fbdev->cb_base) {
                dev_err(&dev->dev, "cannot allocate DMA CBs\n");
                ret = -ENOMEM;
                goto free_fb;
        }
 
-       pr_info("BCM2708FB: allocated DMA memory %pad\n", &fb->cb_handle);
-
        ret = bcm_dma_chan_alloc(BCM_DMA_FEATURE_BULK,
-                                &fb->dma_chan_base, &fb->dma_irq);
+                                &fbdev->dma_chan_base,
+                                &fbdev->dma_irq);
        if (ret < 0) {
-               dev_err(&dev->dev, "couldn't allocate a DMA channel\n");
+               dev_err(&dev->dev, "Couldn't allocate a DMA channel\n");
                goto free_cb;
        }
-       fb->dma_chan = ret;
+       fbdev->dma_chan = ret;
 
-       ret = request_irq(fb->dma_irq, bcm2708_fb_dma_irq,
-                         0, "bcm2708_fb dma", fb);
+       ret = request_irq(fbdev->dma_irq, bcm2708_fb_dma_irq,
+                         0, "bcm2708_fb DMA", fbdev);
        if (ret) {
-               pr_err("%s: failed to request DMA irq\n", __func__);
+               dev_err(&dev->dev,
+                       "Failed to request DMA irq\n");
                goto free_dma_chan;
        }
 
-       pr_info("BCM2708FB: allocated DMA channel %d\n", fb->dma_chan);
+       rpi_firmware_property(fbdev->fw,
+                             RPI_FIRMWARE_GET_VC_MEMORY,
+                             &gpu_mem, sizeof(gpu_mem));
 
-       fb->dev = dev;
-       fb->fb.device = &dev->dev;
+       for (i = 0; i < num_displays; i++) {
+               struct bcm2708_fb *fb = &fbdev->displays[i];
 
-       /* failure here isn't fatal, but we'll fail in vc_mem_copy if
-        * fb->gpu is not valid
-        */
-       rpi_firmware_property(fb->fw, RPI_FIRMWARE_GET_VC_MEMORY, &fb->gpu,
-                             sizeof(fb->gpu));
+               fb->display_settings.display_num = i;
+               fb->dev = dev;
+               fb->fb.device = &dev->dev;
+               fb->fbdev = fbdev;
 
-       ret = bcm2708_fb_register(fb);
-       if (ret == 0) {
-               platform_set_drvdata(dev, fb);
-               goto out;
+               fb->gpu.base = gpu_mem.base;
+               fb->gpu.length = gpu_mem.length;
+
+               if (fbdev->firmware_supports_multifb) {
+                       ret = rpi_firmware_property(fw,
+                                                   RPI_FIRMWARE_FRAMEBUFFER_GET_DISPLAY_SETTINGS,
+                                                   &fb->display_settings,
+                                                   GET_DISPLAY_SETTINGS_PAYLOAD_SIZE);
+               } else {
+                       memset(&fb->display_settings, 0,
+                              sizeof(fb->display_settings));
+               }
+
+               ret = bcm2708_fb_register(fb);
+
+               if (ret == 0) {
+                       bcm2708_fb_debugfs_init(fb);
+
+                       fbdev->num_displays++;
+
+                       dev_info(&dev->dev,
+                                "Registered framebuffer for display %u, size %ux%u\n",
+                                fb->display_settings.display_num,
+                                fb->fb.var.xres,
+                                fb->fb.var.yres);
+               } else {
+                       // Use this to flag if this FB entry is in use.
+                       fb->fbdev = NULL;
+               }
+       }
+
+       // Did we actually successfully create any FB's?
+       if (fbdev->num_displays) {
+               init_waitqueue_head(&fbdev->dma_waitq);
+               platform_set_drvdata(dev, fbdev);
+               return ret;
        }
 
 free_dma_chan:
-       bcm_dma_chan_free(fb->dma_chan);
+       bcm_dma_chan_free(fbdev->dma_chan);
 free_cb:
-       dma_free_wc(&dev->dev, SZ_64K, fb->cb_base, fb->cb_handle);
+       dma_free_wc(&dev->dev, SZ_64K, fbdev->cb_base,
+                             fbdev->cb_handle);
 free_fb:
-       kfree(fb);
-free_region:
        dev_err(&dev->dev, "probe failed, err %d\n", ret);
-out:
+
        return ret;
 }
 
 static int bcm2708_fb_remove(struct platform_device *dev)
 {
-       struct bcm2708_fb *fb = platform_get_drvdata(dev);
+       struct bcm2708_fb_dev *fbdev = platform_get_drvdata(dev);
+       int i;
 
        platform_set_drvdata(dev, NULL);
 
-       if (fb->fb.screen_base)
-               iounmap(fb->fb.screen_base);
-       unregister_framebuffer(&fb->fb);
+       for (i = 0; i < fbdev->num_displays; i++) {
+               if (fbdev->displays[i].fb.screen_base)
+                       iounmap(fbdev->displays[i].fb.screen_base);
 
-       dma_free_wc(&dev->dev, SZ_64K, fb->cb_base, fb->cb_handle);
-       bcm_dma_chan_free(fb->dma_chan);
-
-       bcm2708_fb_debugfs_deinit(fb);
+               if (fbdev->displays[i].fbdev) {
+                       unregister_framebuffer(&fbdev->displays[i].fb);
+                       bcm2708_fb_debugfs_deinit(&fbdev->displays[i]);
+               }
+       }
 
-       free_irq(fb->dma_irq, fb);
+       dma_free_wc(&dev->dev, SZ_64K, fbdev->cb_base,
+                             fbdev->cb_handle);
+       bcm_dma_chan_free(fbdev->dma_chan);
+       free_irq(fbdev->dma_irq, fbdev);
 
-       kfree(fb);
+       mutex_destroy(&fbdev->dma_mutex);
 
        return 0;
 }
@@ -886,10 +1077,10 @@ static struct platform_driver bcm2708_fb_driver = {
        .probe = bcm2708_fb_probe,
        .remove = bcm2708_fb_remove,
        .driver = {
-                  .name = DRIVER_NAME,
-                  .owner = THIS_MODULE,
-                  .of_match_table = bcm2708_fb_of_match_table,
-                  },
+                 .name = DRIVER_NAME,
+                 .owner = THIS_MODULE,
+                 .of_match_table = bcm2708_fb_of_match_table,
+                 },
 };
 
 static int __init bcm2708_fb_init(void)