/*
 * Hardware Random Number Generator support for Cavium Networks
 * Octeon processor family.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2009 Cavium Networks
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/gfp.h>

#include <asm/octeon/octeon.h>
#include <asm/octeon/cvmx-rnm-defs.h>

struct octeon_rng {
        struct hwrng ops;
        void __iomem *control_status;
        void __iomem *result;
};

static int octeon_rng_init(struct hwrng *rng)
{
        union cvmx_rnm_ctl_status ctl;
        struct octeon_rng *p = container_of(rng, struct octeon_rng, ops);

        ctl.u64 = 0;
        ctl.s.ent_en = 1; /* Enable the entropy source.  */
        ctl.s.rng_en = 1; /* Enable the RNG hardware.  */
        cvmx_write_csr((unsigned long)p->control_status, ctl.u64);
        return 0;
}

static void octeon_rng_cleanup(struct hwrng *rng)
{
        union cvmx_rnm_ctl_status ctl;
        struct octeon_rng *p = container_of(rng, struct octeon_rng, ops);

        ctl.u64 = 0;
        /* Disable everything.  */
        cvmx_write_csr((unsigned long)p->control_status, ctl.u64);
}

static int octeon_rng_data_read(struct hwrng *rng, u32 *data)
{
        struct octeon_rng *p = container_of(rng, struct octeon_rng, ops);

        *data = cvmx_read64_uint32((unsigned long)p->result);
        return sizeof(u32);
}

static int octeon_rng_probe(struct platform_device *pdev)
{
        struct resource *res_ports;
        struct resource *res_result;
        struct octeon_rng *rng;
        int ret;
        struct hwrng ops = {
                .name = "octeon",
                .init = octeon_rng_init,
                .cleanup = octeon_rng_cleanup,
                .data_read = octeon_rng_data_read
        };

        rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
        if (!rng)
                return -ENOMEM;

        res_ports = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res_ports)
                return -ENOENT;

        res_result = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!res_result)
                return -ENOENT;


        rng->control_status = devm_ioremap(&pdev->dev,
                                                   res_ports->start,
                                                   sizeof(u64));
        if (!rng->control_status)
                return -ENOENT;

        rng->result = devm_ioremap(&pdev->dev,
                                           res_result->start,
                                           sizeof(u64));
        if (!rng->result)
                return -ENOENT;

        rng->ops = ops;

        platform_set_drvdata(pdev, &rng->ops);
        ret = devm_hwrng_register(&pdev->dev, &rng->ops);
        if (ret)
                return -ENOENT;

        dev_info(&pdev->dev, "Octeon Random Number Generator\n");

        return 0;
}

static struct platform_driver octeon_rng_driver = {
        .driver = {
                .name           = "octeon_rng",
        },
        .probe          = octeon_rng_probe,
};

module_platform_driver(octeon_rng_driver);

MODULE_AUTHOR("David Daney");
MODULE_LICENSE("GPL");