// SPDX-License-Identifier: GPL-2.0-only
/*
 * ntpfw.c - Firmware helper functions for Neofidelity codecs
 *
 * Copyright (c) 2024, SaluteDevices. All Rights Reserved.
 */

#include <linux/i2c.h>
#include <linux/firmware.h>
#include <linux/module.h>

#include "ntpfw.h"

struct ntpfw_chunk {
        __be16 length;
        u8 step;
        u8 data[];
} __packed;

struct ntpfw_header {
        __be32 magic;
} __packed;

static bool ntpfw_verify(struct device *dev, const u8 *buf, size_t buf_size, u32 magic)
{
        const struct ntpfw_header *header = (struct ntpfw_header *)buf;
        u32 buf_magic;

        if (buf_size <= sizeof(*header)) {
                dev_err(dev, "Failed to load firmware: image too small\n");
                return false;
        }

        buf_magic = be32_to_cpu(header->magic);
        if (buf_magic != magic) {
                dev_err(dev, "Failed to load firmware: invalid magic 0x%x:\n", buf_magic);
                return false;
        }

        return true;
}

static bool ntpfw_verify_chunk(struct device *dev, const struct ntpfw_chunk *chunk, size_t buf_size)
{
        size_t chunk_size;

        if (buf_size <= sizeof(*chunk)) {
                dev_err(dev, "Failed to load firmware: chunk size too big\n");
                return false;
        }

        if (chunk->step != 2 && chunk->step != 5) {
                dev_err(dev, "Failed to load firmware: invalid chunk step: %d\n", chunk->step);
                return false;
        }

        chunk_size = be16_to_cpu(chunk->length);
        if (chunk_size > buf_size) {
                dev_err(dev, "Failed to load firmware: invalid chunk length\n");
                return false;
        }

        if (chunk_size % chunk->step) {
                dev_err(dev, "Failed to load firmware: chunk length and step mismatch\n");
                return false;
        }

        return true;
}

static int ntpfw_send_chunk(struct i2c_client *i2c, const struct ntpfw_chunk *chunk)
{
        int ret;
        size_t i;
        size_t length = be16_to_cpu(chunk->length);

        for (i = 0; i < length; i += chunk->step) {
                ret = i2c_master_send(i2c, &chunk->data[i], chunk->step);
                if (ret != chunk->step) {
                        dev_err(&i2c->dev, "I2C send failed: %d\n", ret);
                        return ret < 0 ? ret : -EIO;
                }
        }

        return 0;
}

int ntpfw_load(struct i2c_client *i2c, const char *name, u32 magic)
{
        struct device *dev = &i2c->dev;
        const struct ntpfw_chunk *chunk;
        const struct firmware *fw;
        const u8 *data;
        size_t leftover;
        int ret;

        ret = request_firmware(&fw, name, dev);
        if (ret) {
                dev_warn(dev, "request_firmware '%s' failed with %d\n",
                         name, ret);
                return ret;
        }

        if (!ntpfw_verify(dev, fw->data, fw->size, magic)) {
                ret = -EINVAL;
                goto done;
        }

        data = fw->data + sizeof(struct ntpfw_header);
        leftover = fw->size - sizeof(struct ntpfw_header);

        while (leftover) {
                chunk = (struct ntpfw_chunk *)data;

                if (!ntpfw_verify_chunk(dev, chunk, leftover)) {
                        ret = -EINVAL;
                        goto done;
                }

                ret = ntpfw_send_chunk(i2c, chunk);
                if (ret)
                        goto done;

                data += be16_to_cpu(chunk->length) + sizeof(*chunk);
                leftover -= be16_to_cpu(chunk->length) + sizeof(*chunk);
        }

done:
        release_firmware(fw);

        return ret;
}
EXPORT_SYMBOL_GPL(ntpfw_load);

MODULE_AUTHOR("Igor Prusov <ivprusov@salutedevices.com>");
MODULE_DESCRIPTION("Helper for loading Neofidelity amplifiers firmware");
MODULE_LICENSE("GPL");