text: // 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:
  	iounmap(info->screen_base);
  
  err_release_fb:
  	framebuffer_release(info);
  
  err_release_regions:
  	pci_release_regions(pdev);
  
  	return ret;
  }
  
  static void mdpy_fb_remove(struct pci_dev *pdev)
  {
  	struct fb_info *info = pci_get_drvdata(pdev);
  
  	unregister_framebuffer(info);
  	framebuffer_release(info);
  }
  
  static struct pci_device_id mdpy_fb_pci_table[] = {
  	{
  		.vendor	   = MDPY_PCI_VENDOR_ID,
  		.device	   = MDPY_PCI_DEVICE_ID,
  		.subvendor = MDPY_PCI_SUBVENDOR_ID,
  		.subdevice = MDPY_PCI_SUBDEVICE_ID,
  	}, {
  		/* end of list */
  	}
  };
  
  static struct pci_driver mdpy_fb_pci_driver = {
  	.name		= "mdpy-fb",
  	.id_table	= mdpy_fb_pci_table,
  	.probe		= mdpy_fb_probe,
  	.remove		= mdpy_fb_remove,
  };
  
  static int __init mdpy_fb_init(void)
  {
  	int ret;
  
  	ret = pci_register_driver(&mdpy_fb_pci_driver);
  	if (ret)
  		return ret;
  
  	return 0;
  }
  
  module_init(mdpy_fb_init);
  
  MODULE_DEVICE_TABLE(pci, mdpy_fb_pci_table);
  MODULE_LICENSE("GPL v2");
  