// SPDX-License-Identifier: GPL-2.0
/*
 * drivers/char/hw_random/ixp4xx-rng.c
 *
 * RNG driver for Intel IXP4xx family of NPUs
 *
 * Author: Deepak Saxena <dsaxena@plexity.net>
 *
 * Copyright 2005 (c) MontaVista Software, Inc.
 *
 * Fixes by Michael Buesch
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <linux/hw_random.h>
#include <linux/of.h>
#include <linux/soc/ixp4xx/cpu.h>

#include <asm/io.h>

static int ixp4xx_rng_data_read(struct hwrng *rng, u32 *buffer)
{
        void __iomem * rng_base = (void __iomem *)rng->priv;

        *buffer = __raw_readl(rng_base);

        return 4;
}

static struct hwrng ixp4xx_rng_ops = {
        .name           = "ixp4xx",
        .data_read      = ixp4xx_rng_data_read,
};

static int ixp4xx_rng_probe(struct platform_device *pdev)
{
        void __iomem * rng_base;
        struct device *dev = &pdev->dev;

        if (!cpu_is_ixp46x()) /* includes IXP455 */
                return -ENOSYS;

        rng_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(rng_base))
                return PTR_ERR(rng_base);

        ixp4xx_rng_ops.priv = (unsigned long)rng_base;
        return devm_hwrng_register(dev, &ixp4xx_rng_ops);
}

static const struct of_device_id ixp4xx_rng_of_match[] = {
        {
                .compatible = "intel,ixp46x-rng",
        },
        {},
};
MODULE_DEVICE_TABLE(of, ixp4xx_rng_of_match);

static struct platform_driver ixp4xx_rng_driver = {
        .driver = {
                .name = "ixp4xx-hwrandom",
                .of_match_table = ixp4xx_rng_of_match,
        },
        .probe = ixp4xx_rng_probe,
};
module_platform_driver(ixp4xx_rng_driver);

MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
MODULE_DESCRIPTION("H/W Pseudo-Random Number Generator (RNG) driver for IXP45x/46x");
MODULE_LICENSE("GPL");