// 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/module.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>
#include <linux/sysfb.h>

#include "coreboot_table.h"

#define CB_TAG_FRAMEBUFFER 0x12

static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;

static int framebuffer_probe(struct coreboot_device *dev)
{
        int i;
        u32 length;
        struct lb_framebuffer *fb = &dev->framebuffer;
        struct platform_device *pdev;
        struct resource res;
        struct simplefb_platform_data pdata = {
                .width = fb->x_resolution,
                .height = fb->y_resolution,
                .stride = fb->bytes_per_line,
                .format = NULL,
        };

        /*
         * 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;

        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)
                return -ENODEV;

        memset(&res, 0, sizeof(res));
        res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
        res.name = "Coreboot Framebuffer";
        res.start = fb->physical_address;
        length = PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line);
        res.end = res.start + length - 1;
        if (res.end <= res.start)
                return -EINVAL;

        pdev = platform_device_register_resndata(&dev->dev,
                                                 "simple-framebuffer", 0,
                                                 &res, 1, &pdata,
                                                 sizeof(pdata));
        if (IS_ERR(pdev))
                pr_warn("coreboot: could not register framebuffer\n");
        else
                dev_set_drvdata(&dev->dev, pdev);

        return PTR_ERR_OR_ZERO(pdev);
}

static void framebuffer_remove(struct coreboot_device *dev)
{
        struct platform_device *pdev = dev_get_drvdata(&dev->dev);

        platform_device_unregister(pdev);
}

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,
        .remove = framebuffer_remove,
        .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");