// SPDX-License-Identifier: GPL-2.0-only
/*
 * framebuffer-coreboot.c
 *
 * Memory based framebuffer accessed through coreboot table.
 *
 * Copyright 2012-2013 David Herrmann <dh.herrmann@gmail.com>
 * Copyright 2017 Google Inc.
 * Copyright 2017 Samuel Holland <samuel@sholland.org>
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/device-id/coreboot.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>
#include <linux/sysfb.h>

#include "coreboot_table.h"

#if defined(CONFIG_PCI)
static bool framebuffer_pci_dev_is_enabled(struct pci_dev *pdev)
{
        /*
         * TODO: Try to integrate this code into the PCI subsystem
         */
        int ret;
        u16 command;

        ret = pci_read_config_word(pdev, PCI_COMMAND, &command);
        if (ret != PCIBIOS_SUCCESSFUL)
                return false;
        if (!(command & PCI_COMMAND_MEMORY))
                return false;
        return true;
}

static struct pci_dev *framebuffer_parent_pci_dev(struct resource *res)
{
        struct pci_dev *pdev = NULL;
        const struct resource *r = NULL;

        while (!r && (pdev = pci_get_base_class(PCI_BASE_CLASS_DISPLAY, pdev)))
                r = pci_find_resource(pdev, res);

        if (!r || !pdev)
                return NULL; /* not found; not an error */

        if (!framebuffer_pci_dev_is_enabled(pdev)) {
                pci_dev_put(pdev);
                return ERR_PTR(-ENODEV);
        }

        return pdev;
}
#else
static struct pci_dev *framebuffer_parent_pci_dev(struct resource *res)
{
        return NULL;
}
#endif

static struct device *framebuffer_parent_dev(struct resource *res)
{
        struct pci_dev *pdev;

        pdev = framebuffer_parent_pci_dev(res);
        if (IS_ERR(pdev))
                return ERR_CAST(pdev);
        else if (pdev)
                return &pdev->dev;

        return NULL;
}

static int framebuffer_probe(struct coreboot_device *dev)
{
        struct lb_framebuffer *fb = &dev->framebuffer;
        struct device *parent;
        struct platform_device *pdev;
        struct resource res;
        int ret;
#if !IS_ENABLED(CONFIG_DRM_COREBOOTDRM)
        struct simplefb_platform_data pdata = {
                .width = fb->x_resolution,
                .height = fb->y_resolution,
                .stride = fb->bytes_per_line,
                .format = NULL,
        };
        int i;
        static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
#endif

        /*
         * On coreboot systems, the advertised LB_TAG_FRAMEBUFFER entry
         * in the coreboot table should only be used if the payload did
         * not pass a framebuffer information to the Linux kernel.
         *
         * If the global screen_info data has been filled, the Generic
         * System Framebuffers (sysfb) will already register a platform
         * device and pass that screen_info as platform_data to a driver
         * that can scan-out using the system provided framebuffer.
         */
        if (sysfb_handles_screen_info())
                return -ENODEV;

        if (!fb->physical_address)
                return -ENODEV;

        res = DEFINE_RES_MEM(fb->physical_address,
                             PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line));
        if (res.end <= res.start)
                return -EINVAL;

        parent = framebuffer_parent_dev(&res);
        if (IS_ERR(parent))
                return PTR_ERR(parent);

#if IS_ENABLED(CONFIG_DRM_COREBOOTDRM)
        pdev = platform_device_register_resndata(parent, "coreboot-framebuffer", 0,
                                                 &res, 1, fb, fb->size);
        if (IS_ERR(pdev)) {
                pr_warn("coreboot: could not register framebuffer\n");
                ret = PTR_ERR(pdev);
                goto out_put_device_parent;
        }
#else
        /*
         * FIXME: Coreboot systems should use a driver that binds to
         *        coreboot-framebuffer devices. Remove support for
         *        simple-framebuffer at some point.
         */
        for (i = 0; i < ARRAY_SIZE(formats); ++i) {
                if (fb->bits_per_pixel     == formats[i].bits_per_pixel &&
                    fb->red_mask_pos       == formats[i].red.offset &&
                    fb->red_mask_size      == formats[i].red.length &&
                    fb->green_mask_pos     == formats[i].green.offset &&
                    fb->green_mask_size    == formats[i].green.length &&
                    fb->blue_mask_pos      == formats[i].blue.offset &&
                    fb->blue_mask_size     == formats[i].blue.length)
                        pdata.format = formats[i].name;
        }
        if (!pdata.format) {
                ret = -ENODEV;
                goto out_put_device_parent;
        }

        pdev = platform_device_register_resndata(parent,
                                                 "simple-framebuffer", 0,
                                                 &res, 1, &pdata,
                                                 sizeof(pdata));
        if (IS_ERR(pdev)) {
                ret = PTR_ERR(pdev);
                pr_warn("coreboot: could not register framebuffer\n");
                goto out_put_device_parent;
        }
#endif

        ret = 0;

out_put_device_parent:
        if (parent)
                put_device(parent);
        return ret;
}

static const struct coreboot_device_id framebuffer_ids[] = {
        { .tag = CB_TAG_FRAMEBUFFER },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(coreboot, framebuffer_ids);

static struct coreboot_driver framebuffer_driver = {
        .probe = framebuffer_probe,
        .drv = {
                .name = "framebuffer",
        },
        .id_table = framebuffer_ids,
};
module_coreboot_driver(framebuffer_driver);

MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");
MODULE_DESCRIPTION("Memory based framebuffer accessed through coreboot table");
MODULE_LICENSE("GPL");