// 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 const struct fb_ops mdpy_fb_ops = {
        .owner          = THIS_MODULE,
        FB_DEFAULT_IOMEM_OPS,
        .fb_destroy     = mdpy_fb_destroy,
        .fb_setcolreg   = mdpy_fb_setcolreg,
};

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)
                goto err_disable_dev;

        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);
                ret = -EINVAL;
                goto err_release_regions;
        }
        if (width < 100  || width > 10000) {
                pci_err(pdev, "width (%d) out of range\n", width);
                ret = -EINVAL;
                goto err_release_regions;
        }
        if (height < 100 || height > 10000) {
                pci_err(pdev, "height (%d) out of range\n", height);
                ret = -EINVAL;
                goto err_release_regions;
        }
        pci_info(pdev, "mdpy found: %dx%d framebuffer\n",
                 width, height);

        info = framebuffer_alloc(sizeof(struct mdpy_fb_par), &pdev->dev);
        if (!info) {
                ret = -ENOMEM;
                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->fbops = &mdpy_fb_ops;
        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);

err_disable_dev:
        pci_disable_device(pdev);

        return ret;
}

static void mdpy_fb_remove(struct pci_dev *pdev)
{
        struct fb_info *info = pci_get_drvdata(pdev);

        unregister_framebuffer(info);
        iounmap(info->screen_base);
        framebuffer_release(info);
        pci_release_regions(pdev);
        pci_disable_device(pdev);
}

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_DESCRIPTION("Framebuffer driver for mdpy (mediated virtual pci display device)");
MODULE_LICENSE("GPL v2");