sample: vfio mdev display - guest driver

Guest fbdev driver for CONFIG_SAMPLE_VFIO_MDEV_MDPY.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

3 files changed, 242 insertions, 0 deletions

diff --git a/samples/Kconfig b/samples/Kconfig
index 960f19b24df0..a6ff147d8744 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -123,6 +123,15 @@ config SAMPLE_VFIO_MDEV_MDPY
           mediated device.  It is a simple framebuffer and supports
           the region display interface (VFIO_GFX_PLANE_TYPE_REGION).
 
+config SAMPLE_VFIO_MDEV_MDPY_FB
+        tristate "Build VFIO mdpy example guest fbdev driver -- loadable module only"
+        depends on FB && m
+        select FB_CFB_FILLRECT
+        select FB_CFB_COPYAREA
+        select FB_CFB_IMAGEBLIT
+        help
+          Guest fbdev driver for the virtual display sample driver.
+
 config SAMPLE_STATX
         bool "Build example extended-stat using code"
         depends on BROKEN
diff --git a/samples/vfio-mdev/Makefile b/samples/vfio-mdev/Makefile
index 031d6b88e9e9..7a5790aaec9c 100644
--- a/samples/vfio-mdev/Makefile
+++ b/samples/vfio-mdev/Makefile
@@ -1,2 +1,3 @@
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MTTY) += mtty.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY) += mdpy.o
+obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY_FB) += mdpy-fb.o
diff --git a/samples/vfio-mdev/mdpy-fb.c b/samples/vfio-mdev/mdpy-fb.c
new file mode 100644
index 000000000000..2719bb259653
--- /dev/null
+++ b/samples/vfio-mdev/mdpy-fb.c
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Framebuffer driver for mdpy (mediated virtual pci display device).
+ *
+ * See mdpy-defs.h for device specs
+ *
+ *   (c) Gerd Hoffmann <kraxel@redhat.com>
+ *
+ * Using some code snippets from simplefb and cirrusfb.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+#include <linux/errno.h>
+#include <linux/fb.h>
+#include <linux/io.h>
+#include <linux/pci.h>
+#include <linux/module.h>
+#include <drm/drm_fourcc.h>
+#include "mdpy-defs.h"
+
+static const struct fb_fix_screeninfo mdpy_fb_fix = {
+        .id             = "mdpy-fb",
+        .type           = FB_TYPE_PACKED_PIXELS,
+        .visual         = FB_VISUAL_TRUECOLOR,
+        .accel          = FB_ACCEL_NONE,
+};
+
+static const struct fb_var_screeninfo mdpy_fb_var = {
+        .height         = -1,
+        .width          = -1,
+        .activate       = FB_ACTIVATE_NOW,
+        .vmode          = FB_VMODE_NONINTERLACED,
+
+        .bits_per_pixel = 32,
+        .transp.offset  = 24,
+        .red.offset     = 16,
+        .green.offset   = 8,
+        .blue.offset    = 0,
+        .transp.length  = 8,
+        .red.length     = 8,
+        .green.length   = 8,
+        .blue.length    = 8,
+};
+
+#define PSEUDO_PALETTE_SIZE 16
+
+struct mdpy_fb_par {
+        u32 palette[PSEUDO_PALETTE_SIZE];
+};
+
+static int mdpy_fb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
+                              u_int transp, struct fb_info *info)
+{
+        u32 *pal = info->pseudo_palette;
+        u32 cr = red >> (16 - info->var.red.length);
+        u32 cg = green >> (16 - info->var.green.length);
+        u32 cb = blue >> (16 - info->var.blue.length);
+        u32 value, mask;
+
+        if (regno >= PSEUDO_PALETTE_SIZE)
+                return -EINVAL;
+
+        value = (cr << info->var.red.offset) |
+                (cg << info->var.green.offset) |
+                (cb << info->var.blue.offset);
+        if (info->var.transp.length > 0) {
+                mask = (1 << info->var.transp.length) - 1;
+                mask <<= info->var.transp.offset;
+                value |= mask;
+        }
+        pal[regno] = value;
+
+        return 0;
+}
+
+static void mdpy_fb_destroy(struct fb_info *info)
+{
+        if (info->screen_base)
+                iounmap(info->screen_base);
+}
+
+static struct fb_ops mdpy_fb_ops = {
+        .owner          = THIS_MODULE,
+        .fb_destroy     = mdpy_fb_destroy,
+        .fb_setcolreg   = mdpy_fb_setcolreg,
+        .fb_fillrect    = cfb_fillrect,
+        .fb_copyarea    = cfb_copyarea,
+        .fb_imageblit   = cfb_imageblit,
+};
+
+static int mdpy_fb_probe(struct pci_dev *pdev,
+                         const struct pci_device_id *ent)
+{
+        struct fb_info *info;
+        struct mdpy_fb_par *par;
+        u32 format, width, height;
+        int ret;
+
+        ret = pci_enable_device(pdev);
+        if (ret < 0)
+                return ret;
+
+        ret = pci_request_regions(pdev, "mdpy-fb");
+        if (ret < 0)
+                return ret;
+
+        pci_read_config_dword(pdev, MDPY_FORMAT_OFFSET, &format);
+        pci_read_config_dword(pdev, MDPY_WIDTH_OFFSET,  &width);
+        pci_read_config_dword(pdev, MDPY_HEIGHT_OFFSET, &height);
+        if (format != DRM_FORMAT_XRGB8888) {
+                pci_err(pdev, "format mismatch (0x%x != 0x%x)\n",
+                        format, DRM_FORMAT_XRGB8888);
+                return -EINVAL;
+        }
+        if (width < 100  || width > 10000) {
+                pci_err(pdev, "width (%d) out of range\n", width);
+                return -EINVAL;
+        }
+        if (height < 100 || height > 10000) {
+                pci_err(pdev, "height (%d) out of range\n", height);
+                return -EINVAL;
+        }
+        pci_info(pdev, "mdpy found: %dx%d framebuffer\n",
+                 width, height);
+
+        info = framebuffer_alloc(sizeof(struct mdpy_fb_par), &pdev->dev);
+        if (!info)
+                goto err_release_regions;
+        pci_set_drvdata(pdev, info);
+        par = info->par;
+
+        info->fix = mdpy_fb_fix;
+        info->fix.smem_start = pci_resource_start(pdev, 0);
+        info->fix.smem_len = pci_resource_len(pdev, 0);
+        info->fix.line_length = width * 4;
+
+        info->var = mdpy_fb_var;
+        info->var.xres = width;
+        info->var.yres = height;
+        info->var.xres_virtual = width;
+        info->var.yres_virtual = height;
+
+        info->screen_size = info->fix.smem_len;
+        info->screen_base = ioremap(info->fix.smem_start,
+                                    info->screen_size);
+        if (!info->screen_base) {
+                pci_err(pdev, "ioremap(pcibar) failed\n");
+                ret = -EIO;
+                goto err_release_fb;
+        }
+
+        info->apertures = alloc_apertures(1);
+        if (!info->apertures) {
+                ret = -ENOMEM;
+                goto err_unmap;
+        }
+        info->apertures->ranges[0].base = info->fix.smem_start;
+        info->apertures->ranges[0].size = info->fix.smem_len;
+
+        info->fbops = &mdpy_fb_ops;
+        info->flags = FBINFO_DEFAULT;
+        info->pseudo_palette = par->palette;
+
+        ret = register_framebuffer(info);
+        if (ret < 0) {
+                pci_err(pdev, "mdpy-fb device register failed: %d\n", ret);
+                goto err_unmap;
+        }
+
+        pci_info(pdev, "fb%d registered\n", info->node);
+        return 0;
+
+err_unmap: