// SPDX-License-Identifier: GPL-2.0-only
/*
 * Generic PowerPC 44x RNG driver
 *
 * Copyright 2011 IBM Corporation
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/hw_random.h>
#include <linux/delay.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/io.h>

#include "crypto4xx_core.h"
#include "crypto4xx_trng.h"
#include "crypto4xx_reg_def.h"

#define PPC4XX_TRNG_CTRL        0x0008
#define PPC4XX_TRNG_CTRL_DALM   0x20
#define PPC4XX_TRNG_STAT        0x0004
#define PPC4XX_TRNG_STAT_B      0x1
#define PPC4XX_TRNG_DATA        0x0000

static int ppc4xx_trng_data_present(struct hwrng *rng, int wait)
{
        struct crypto4xx_device *dev = (void *)rng->priv;
        int busy, i, present = 0;

        for (i = 0; i < 20; i++) {
                busy = (in_le32(dev->trng_base + PPC4XX_TRNG_STAT) &
                        PPC4XX_TRNG_STAT_B);
                if (!busy || !wait) {
                        present = 1;
                        break;
                }
                udelay(10);
        }
        return present;
}

static int ppc4xx_trng_data_read(struct hwrng *rng, u32 *data)
{
        struct crypto4xx_device *dev = (void *)rng->priv;
        *data = in_le32(dev->trng_base + PPC4XX_TRNG_DATA);
        return 4;
}

static void ppc4xx_trng_enable(struct crypto4xx_device *dev, bool enable)
{
        u32 device_ctrl;

        device_ctrl = readl(dev->ce_base + CRYPTO4XX_DEVICE_CTRL);
        if (enable)
                device_ctrl |= PPC4XX_TRNG_EN;
        else
                device_ctrl &= ~PPC4XX_TRNG_EN;
        writel(device_ctrl, dev->ce_base + CRYPTO4XX_DEVICE_CTRL);
}

static const struct of_device_id ppc4xx_trng_match[] = {
        { .compatible = "ppc4xx-rng", },
        { .compatible = "amcc,ppc460ex-rng", },
        { .compatible = "amcc,ppc440epx-rng", },
        {},
};

void ppc4xx_trng_probe(struct crypto4xx_core_device *core_dev)
{
        struct crypto4xx_device *dev = core_dev->dev;
        struct device_node *trng = NULL;
        struct hwrng *rng = NULL;
        int err;

        /* Find the TRNG device node and map it */
        trng = of_find_matching_node(NULL, ppc4xx_trng_match);
        if (!trng || !of_device_is_available(trng)) {
                of_node_put(trng);
                return;
        }

        dev->trng_base = of_iomap(trng, 0);
        of_node_put(trng);
        if (!dev->trng_base)
                goto err_out;

        rng = kzalloc_obj(*rng);
        if (!rng)
                goto err_out;

        rng->name = KBUILD_MODNAME;
        rng->data_present = ppc4xx_trng_data_present;
        rng->data_read = ppc4xx_trng_data_read;
        rng->priv = (unsigned long) dev;
        core_dev->trng = rng;
        ppc4xx_trng_enable(dev, true);
        out_le32(dev->trng_base + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM);
        err = devm_hwrng_register(core_dev->device, core_dev->trng);
        if (err) {
                ppc4xx_trng_enable(dev, false);
                dev_err(core_dev->device, "failed to register hwrng (%d).\n",
                        err);
                goto err_out;
        }
        return;

err_out:
        iounmap(dev->trng_base);
        kfree(rng);
        dev->trng_base = NULL;
        core_dev->trng = NULL;
}

void ppc4xx_trng_remove(struct crypto4xx_core_device *core_dev)
{
        if (core_dev && core_dev->trng) {
                struct crypto4xx_device *dev = core_dev->dev;

                devm_hwrng_unregister(core_dev->device, core_dev->trng);
                ppc4xx_trng_enable(dev, false);
                iounmap(dev->trng_base);
                kfree(core_dev->trng);
        }
}

MODULE_ALIAS("ppc4xx_rng");