// SPDX-License-Identifier: GPL-2.0
/*
 * sun8i-ce-trng.c - hardware cryptographic offloader for
 * Allwinner H3/A64/H5/H2+/H6/R40 SoC
 *
 * Copyright (C) 2015-2020 Corentin Labbe <clabbe@baylibre.com>
 *
 * This file handle the TRNG
 *
 * You could find a link for the datasheet in Documentation/arch/arm/sunxi.rst
 */
#include "sun8i-ce.h"
#include <linux/dma-mapping.h>
#include <linux/pm_runtime.h>
#include <linux/hw_random.h>
/*
 * Note that according to the algorithm ID, 2 versions of the TRNG exists,
 * The first present in H3/H5/R40/A64 and the second present in H6.
 * This file adds support for both, but only the second is working
 * reliabily according to rngtest.
 **/

static int sun8i_ce_trng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
        struct sun8i_ce_dev *ce;
        dma_addr_t dma_dst;
        int err = 0;
        int flow = 3;
        unsigned int todo;
        struct sun8i_ce_flow *chan;
        struct ce_task *cet;
        u32 common;
        void *d;

        ce = container_of(rng, struct sun8i_ce_dev, trng);

        /* round the data length to a multiple of 32*/
        todo = max + 32;
        todo -= todo % 32;

        d = kzalloc(todo, GFP_KERNEL | GFP_DMA);
        if (!d)
                return -ENOMEM;

#ifdef CONFIG_CRYPTO_DEV_SUN8I_CE_DEBUG
        ce->hwrng_stat_req++;
        ce->hwrng_stat_bytes += todo;
#endif

        dma_dst = dma_map_single(ce->dev, d, todo, DMA_FROM_DEVICE);
        if (dma_mapping_error(ce->dev, dma_dst)) {
                dev_err(ce->dev, "Cannot DMA MAP DST\n");
                err = -EFAULT;
                goto err_dst;
        }

        err = pm_runtime_resume_and_get(ce->dev);
        if (err < 0)
                goto err_pm;

        mutex_lock(&ce->rnglock);
        chan = &ce->chanlist[flow];

        cet = &chan->tl[0];
        memset(cet, 0, sizeof(struct ce_task));

        cet->t_id = cpu_to_le32(flow);
        common = ce->variant->trng | CE_COMM_INT;
        cet->t_common_ctl = cpu_to_le32(common);

        /* recent CE (H6) need length in bytes, in word otherwise */
        if (ce->variant->trng_t_dlen_in_bytes)
                cet->t_dlen = cpu_to_le32(todo);
        else
                cet->t_dlen = cpu_to_le32(todo / 4);

        cet->t_sym_ctl = 0;
        cet->t_asym_ctl = 0;

        cet->t_dst[0].addr = desc_addr_val_le32(ce, dma_dst);
        cet->t_dst[0].len = cpu_to_le32(todo / 4);

        err = sun8i_ce_run_task(ce, 3, "TRNG");
        mutex_unlock(&ce->rnglock);

        pm_runtime_put(ce->dev);

err_pm:
        dma_unmap_single(ce->dev, dma_dst, todo, DMA_FROM_DEVICE);

        if (!err) {
                memcpy(data, d, max);
                err = max;
        }
err_dst:
        kfree_sensitive(d);
        return err;
}

int sun8i_ce_hwrng_register(struct sun8i_ce_dev *ce)
{
        int ret;

        if (ce->variant->trng == CE_ID_NOTSUPP) {
                dev_info(ce->dev, "TRNG not supported\n");
                return 0;
        }
        ce->trng.name = "sun8i Crypto Engine TRNG";
        ce->trng.read = sun8i_ce_trng_read;

        ret = hwrng_register(&ce->trng);
        if (ret)
                dev_err(ce->dev, "Fail to register the TRNG\n");
        return ret;
}

void sun8i_ce_hwrng_unregister(struct sun8i_ce_dev *ce)
{
        if (ce->variant->trng == CE_ID_NOTSUPP)
                return;
        hwrng_unregister(&ce->trng);
}