/*
 * Copyright 2014 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: Ben Skeggs <bskeggs@redhat.com>
 */
#include "priv.h"

#include <core/option.h>
#include <subdev/bios.h>
#include <subdev/bios/image.h>

struct shadow {
        u32 skip;
        const struct nvbios_source *func;
        void *data;
        u32 size;
        int score;
};

static bool
shadow_fetch(struct nvkm_bios *bios, struct shadow *mthd, u32 upto)
{
        const u32 limit = (upto + 3) & ~3;
        const u32 start = bios->size;
        void *data = mthd->data;
        if (nvbios_extend(bios, limit) > 0) {
                u32 read = mthd->func->read(data, start, limit - start, bios);
                bios->size = start + read;
        }
        return bios->size >= upto;
}

static int
shadow_image(struct nvkm_bios *bios, int idx, u32 offset, struct shadow *mthd)
{
        struct nvkm_subdev *subdev = &bios->subdev;
        struct nvbios_image image;
        int score = 1;

        if (mthd->func->no_pcir) {
                image.base = 0;
                image.type = 0;
                image.size = mthd->func->size(mthd->data);
                image.last = 1;
        } else {
                if (!shadow_fetch(bios, mthd, offset + 0x1000)) {
                        nvkm_debug(subdev, "%08x: header fetch failed\n",
                                   offset);
                        return 0;
                }

                if (!nvbios_image(bios, idx, &image)) {
                        nvkm_debug(subdev, "image %d invalid\n", idx);
                        return 0;
                }
        }
        nvkm_debug(subdev, "%08x: type %02x, %d bytes\n",
                   image.base, image.type, image.size);

        if (!shadow_fetch(bios, mthd, image.size)) {
                nvkm_debug(subdev, "%08x: fetch failed\n", image.base);
                return 0;
        }

        switch (image.type) {
        case 0x00:
                if (!mthd->func->ignore_checksum &&
                    nvbios_checksum(&bios->data[image.base], image.size)) {
                        nvkm_debug(subdev, "%08x: checksum failed\n",
                                   image.base);
                        if (!mthd->func->require_checksum) {
                                if (mthd->func->rw)
                                        score += 1;
                                score += 1;
                        } else
                                return 0;
                } else {
                        score += 3;
                }
                break;
        default:
                score += 3;
                break;
        }

        if (!image.last)
                score += shadow_image(bios, idx + 1, offset + image.size, mthd);
        return score;
}

static int
shadow_method(struct nvkm_bios *bios, struct shadow *mthd, const char *name)
{
        const struct nvbios_source *func = mthd->func;
        struct nvkm_subdev *subdev = &bios->subdev;
        if (func->name) {
                nvkm_debug(subdev, "trying %s...\n", name ? name : func->name);
                if (func->init) {
                        mthd->data = func->init(bios, name);
                        if (IS_ERR(mthd->data)) {
                                mthd->data = NULL;
                                return 0;
                        }
                }
                mthd->score = shadow_image(bios, 0, 0, mthd);
                if (func->fini)
                        func->fini(mthd->data);
                nvkm_debug(subdev, "scored %d\n", mthd->score);
                mthd->data = bios->data;
                mthd->size = bios->size;
                bios->data  = NULL;
                bios->size  = 0;
        }
        return mthd->score;
}

static u32
shadow_fw_read(void *data, u32 offset, u32 length, struct nvkm_bios *bios)
{
        const struct firmware *fw = data;
        if (offset + length <= fw->size) {
                memcpy(bios->data + offset, fw->data + offset, length);
                return length;
        }
        return 0;
}

static void *
shadow_fw_init(struct nvkm_bios *bios, const char *name)
{
        struct device *dev = bios->subdev.device->dev;
        const struct firmware *fw;
        int ret = request_firmware(&fw, name, dev);
        if (ret)
                return ERR_PTR(-ENOENT);
        return (void *)fw;
}

static const struct nvbios_source
shadow_fw = {
        .name = "firmware",
        .init = shadow_fw_init,
        .fini = (void(*)(void *))release_firmware,
        .read = shadow_fw_read,
        .rw = false,
};

int
nvbios_shadow(struct nvkm_bios *bios)
{
        struct nvkm_subdev *subdev = &bios->subdev;
        struct nvkm_device *device = subdev->device;
        struct shadow mthds[] = {
                { 0, &nvbios_of },
                { 0, &nvbios_ramin },
                { 0, &nvbios_rom },
                { 0, &nvbios_acpi_fast },
                { 4, &nvbios_acpi_slow },
                { 1, &nvbios_pcirom },
                { 1, &nvbios_platform },
                {}
        }, *mthd, *best = NULL;
        const char *optarg;
        char *source;
        int optlen;

        /* handle user-specified bios source */
        optarg = nvkm_stropt(device->cfgopt, "NvBios", &optlen);
        source = optarg ? kstrndup(optarg, optlen, GFP_KERNEL) : NULL;
        if (source) {
                /* try to match one of the built-in methods */
                for (mthd = mthds; mthd->func; mthd++) {
                        if (mthd->func->name &&
                            !strcasecmp(source, mthd->func->name)) {
                                best = mthd;
                                if (shadow_method(bios, mthd, NULL))
                                        break;
                        }
                }

                /* otherwise, attempt to load as firmware */
                if (!best && (best = mthd)) {
                        mthd->func = &shadow_fw;
                        shadow_method(bios, mthd, source);
                        mthd->func = NULL;
                }

                if (!best->score) {
                        nvkm_error(subdev, "%s invalid\n", source);
                        kfree(source);
                        source = NULL;
                }
        }

        /* scan all potential bios sources, looking for best image */
        if (!best || !best->score) {
                for (mthd = mthds, best = mthd; mthd->func; mthd++) {
                        if (!mthd->skip || best->score < mthd->skip) {
                                if (shadow_method(bios, mthd, NULL)) {
                                        if (mthd->score > best->score)
                                                best = mthd;
                                }
                        }
                }
        }

        /* cleanup the ones we didn't use */
        for (mthd = mthds; mthd->func; mthd++) {
                if (mthd != best)
                        kfree(mthd->data);
        }

        if (!best->score) {
                nvkm_error(subdev, "unable to locate usable image\n");
                return -EINVAL;
        }

        nvkm_debug(subdev, "using image from %s\n", best->func ?
                   best->func->name : source);
        bios->data = best->data;
        bios->size = best->size;
        kfree(source);
        return 0;
}