// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Generic System Framebuffers
 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
 */

/*
 * simple-framebuffer probing
 * Try to convert "screen_info" into a "simple-framebuffer" compatible mode.
 * If the mode is incompatible, we return "false" and let the caller create
 * legacy nodes instead.
 */

#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>
#include <linux/screen_info.h>
#include <linux/sysfb.h>

static const char simplefb_resname[] = "BOOTFB";
static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;

/* try parsing screen_info into a simple-framebuffer mode struct */
__init bool sysfb_parse_mode(const struct screen_info *si,
                             struct simplefb_platform_data *mode)
{
        __u8 type;
        u32 bits_per_pixel;
        unsigned int i;

        type = si->orig_video_isVGA;
        if (type != VIDEO_TYPE_VLFB && type != VIDEO_TYPE_EFI)
                return false;

        bits_per_pixel = __screen_info_lfb_bits_per_pixel(si);

        for (i = 0; i < ARRAY_SIZE(formats); ++i) {
                const struct simplefb_format *f = &formats[i];

                if (f->transp.length)
                        continue; /* transparent formats are unsupported by VESA/EFI */

                if (bits_per_pixel == f->bits_per_pixel &&
                    si->red_size == f->red.length &&
                    si->red_pos == f->red.offset &&
                    si->green_size == f->green.length &&
                    si->green_pos == f->green.offset &&
                    si->blue_size == f->blue.length &&
                    si->blue_pos == f->blue.offset) {
                        mode->format = f->name;
                        mode->width = si->lfb_width;
                        mode->height = si->lfb_height;
                        mode->stride = si->lfb_linelength;
                        return true;
                }
        }

        return false;
}

__init struct platform_device *sysfb_create_simplefb(const struct screen_info *si,
                                                     const struct simplefb_platform_data *mode,
                                                     struct device *parent)
{
        struct platform_device *pd;
        struct resource res;
        u64 base, size;
        u32 length;
        int ret;

        /*
         * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
         * upper half of the base address. Assemble the address, then make sure
         * it is valid and we can actually access it.
         */
        base = si->lfb_base;
        if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
                base |= (u64)si->ext_lfb_base << 32;
        if (!base || (u64)(resource_size_t)base != base) {
                printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
                return ERR_PTR(-EINVAL);
        }

        /*
         * Don't use lfb_size as IORESOURCE size, since it may contain the
         * entire VMEM, and thus require huge mappings. Use just the part we
         * need, that is, the part where the framebuffer is located. But verify
         * that it does not exceed the advertised VMEM.
         * Note that in case of VBE, the lfb_size is shifted by 16 bits for
         * historical reasons.
         */
        size = si->lfb_size;
        if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
                size <<= 16;
        length = mode->height * mode->stride;
        if (length > size) {
                printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
                return ERR_PTR(-EINVAL);
        }
        length = PAGE_ALIGN(length);

        /* setup IORESOURCE_MEM as framebuffer memory */
        memset(&res, 0, sizeof(res));
        res.flags = IORESOURCE_MEM;
        res.name = simplefb_resname;
        res.start = base;
        res.end = res.start + length - 1;
        if (res.end <= res.start)
                return ERR_PTR(-EINVAL);

        pd = platform_device_alloc("simple-framebuffer", 0);
        if (!pd)
                return ERR_PTR(-ENOMEM);

        pd->dev.parent = parent;

        sysfb_set_efifb_fwnode(si, pd);

        ret = platform_device_add_resources(pd, &res, 1);
        if (ret)
                goto err_put_device;

        ret = platform_device_add_data(pd, mode, sizeof(*mode));
        if (ret)
                goto err_put_device;

        ret = platform_device_add(pd);
        if (ret)
                goto err_put_device;

        return pd;

err_put_device:
        platform_device_put(pd);

        return ERR_PTR(ret);
}