// SPDX-License-Identifier: GPL-2.0
/*
 * sl3516-ce-cipher.c - hardware cryptographic offloader for Storlink SL3516 SoC
 *
 * Copyright (C) 2021 Corentin LABBE <clabbe@baylibre.com>
 *
 * This file adds support for AES cipher with 128,192,256 bits keysize in
 * ECB mode.
 */

#include <crypto/engine.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "sl3516-ce.h"

/* sl3516_ce_need_fallback - check if a request can be handled by the CE */
static bool sl3516_ce_need_fallback(struct skcipher_request *areq)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(areq);
        struct sl3516_ce_cipher_tfm_ctx *op = crypto_skcipher_ctx(tfm);
        struct sl3516_ce_dev *ce = op->ce;
        struct scatterlist *in_sg;
        struct scatterlist *out_sg;
        struct scatterlist *sg;

        if (areq->cryptlen == 0 || areq->cryptlen % 16) {
                ce->fallback_mod16++;
                return true;
        }

        /*
         * check if we have enough descriptors for TX
         * Note: TX need one control desc for each SG
         */
        if (sg_nents(areq->src) > MAXDESC / 2) {
                ce->fallback_sg_count_tx++;
                return true;
        }
        /* check if we have enough descriptors for RX */
        if (sg_nents(areq->dst) > MAXDESC) {
                ce->fallback_sg_count_rx++;
                return true;
        }

        sg = areq->src;
        while (sg) {
                if ((sg->length % 16) != 0) {
                        ce->fallback_mod16++;
                        return true;
                }
                if ((sg_dma_len(sg) % 16) != 0) {
                        ce->fallback_mod16++;
                        return true;
                }
                if (!IS_ALIGNED(sg->offset, 16)) {
                        ce->fallback_align16++;
                        return true;
                }
                sg = sg_next(sg);
        }
        sg = areq->dst;
        while (sg) {
                if ((sg->length % 16) != 0) {
                        ce->fallback_mod16++;
                        return true;
                }
                if ((sg_dma_len(sg) % 16) != 0) {
                        ce->fallback_mod16++;
                        return true;
                }
                if (!IS_ALIGNED(sg->offset, 16)) {
                        ce->fallback_align16++;
                        return true;
                }
                sg = sg_next(sg);
        }

        /* need same numbers of SG (with same length) for source and destination */
        in_sg = areq->src;
        out_sg = areq->dst;
        while (in_sg && out_sg) {
                if (in_sg->length != out_sg->length) {
                        ce->fallback_not_same_len++;
                        return true;
                }
                in_sg = sg_next(in_sg);
                out_sg = sg_next(out_sg);
        }
        if (in_sg || out_sg)
                return true;

        return false;
}

static int sl3516_ce_cipher_fallback(struct skcipher_request *areq)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(areq);
        struct sl3516_ce_cipher_tfm_ctx *op = crypto_skcipher_ctx(tfm);
        struct sl3516_ce_cipher_req_ctx *rctx = skcipher_request_ctx(areq);
        struct skcipher_alg *alg = crypto_skcipher_alg(tfm);
        struct sl3516_ce_alg_template *algt;
        int err;

        algt = container_of(alg, struct sl3516_ce_alg_template, alg.skcipher.base);
        algt->stat_fb++;

        skcipher_request_set_tfm(&rctx->fallback_req, op->fallback_tfm);
        skcipher_request_set_callback(&rctx->fallback_req, areq->base.flags,
                                      areq->base.complete, areq->base.data);
        skcipher_request_set_crypt(&rctx->fallback_req, areq->src, areq->dst,
                                   areq->cryptlen, areq->iv);
        if (rctx->op_dir == CE_DECRYPTION)
                err = crypto_skcipher_decrypt(&rctx->fallback_req);
        else
                err = crypto_skcipher_encrypt(&rctx->fallback_req);
        return err;
}

static int sl3516_ce_cipher(struct skcipher_request *areq)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(areq);
        struct sl3516_ce_cipher_tfm_ctx *op = crypto_skcipher_ctx(tfm);
        struct sl3516_ce_dev *ce = op->ce;
        struct sl3516_ce_cipher_req_ctx *rctx = skcipher_request_ctx(areq);
        struct skcipher_alg *alg = crypto_skcipher_alg(tfm);
        struct sl3516_ce_alg_template *algt;
        struct scatterlist *sg;
        unsigned int todo, len;
        struct pkt_control_ecb *ecb;
        int nr_sgs = 0;
        int nr_sgd = 0;
        int err = 0;
        int i;

        algt = container_of(alg, struct sl3516_ce_alg_template, alg.skcipher.base);

        dev_dbg(ce->dev, "%s %s %u %x IV(%p %u) key=%u\n", __func__,
                crypto_tfm_alg_name(areq->base.tfm),
                areq->cryptlen,
                rctx->op_dir, areq->iv, crypto_skcipher_ivsize(tfm),
                op->keylen);

        algt->stat_req++;

        if (areq->src == areq->dst) {
                nr_sgs = dma_map_sg(ce->dev, areq->src, sg_nents(areq->src),
                                    DMA_BIDIRECTIONAL);
                if (nr_sgs <= 0 || nr_sgs > MAXDESC / 2) {
                        dev_err(ce->dev, "Invalid sg number %d\n", nr_sgs);
                        err = -EINVAL;
                        goto theend;
                }
                nr_sgd = nr_sgs;
        } else {
                nr_sgs = dma_map_sg(ce->dev, areq->src, sg_nents(areq->src),
                                    DMA_TO_DEVICE);
                if (nr_sgs <= 0 || nr_sgs > MAXDESC / 2) {
                        dev_err(ce->dev, "Invalid sg number %d\n", nr_sgs);
                        err = -EINVAL;
                        goto theend;
                }
                nr_sgd = dma_map_sg(ce->dev, areq->dst, sg_nents(areq->dst),
                                    DMA_FROM_DEVICE);
                if (nr_sgd <= 0 || nr_sgd > MAXDESC) {
                        dev_err(ce->dev, "Invalid sg number %d\n", nr_sgd);
                        err = -EINVAL;
                        goto theend_sgs;
                }
        }

        len = areq->cryptlen;
        i = 0;
        sg = areq->src;
        while (i < nr_sgs && sg && len) {
                if (sg_dma_len(sg) == 0)
                        goto sgs_next;
                rctx->t_src[i].addr = sg_dma_address(sg);
                todo = min(len, sg_dma_len(sg));
                rctx->t_src[i].len = todo;
                dev_dbg(ce->dev, "%s total=%u SGS(%d %u off=%d) todo=%u\n", __func__,
                        areq->cryptlen, i, rctx->t_src[i].len, sg->offset, todo);
                len -= todo;
                i++;
sgs_next:
                sg = sg_next(sg);
        }
        if (len > 0) {
                dev_err(ce->dev, "remaining len %d/%u nr_sgs=%d\n", len, areq->cryptlen, nr_sgs);
                err = -EINVAL;
                goto theend_sgs;
        }

        len = areq->cryptlen;
        i = 0;
        sg = areq->dst;
        while (i < nr_sgd && sg && len) {
                if (sg_dma_len(sg) == 0)
                        goto sgd_next;
                rctx->t_dst[i].addr = sg_dma_address(sg);
                todo = min(len, sg_dma_len(sg));
                rctx->t_dst[i].len = todo;
                dev_dbg(ce->dev, "%s total=%u SGD(%d %u off=%d) todo=%u\n", __func__,
                        areq->cryptlen, i, rctx->t_dst[i].len, sg->offset, todo);
                len -= todo;
                i++;

sgd_next:
                sg = sg_next(sg);
        }
        if (len > 0) {
                dev_err(ce->dev, "remaining len %d\n", len);
                err = -EINVAL;
                goto theend_sgs;
        }

        switch (algt->mode) {
        case ECB_AES:
                rctx->pctrllen = sizeof(struct pkt_control_ecb);
                ecb = (struct pkt_control_ecb *)ce->pctrl;

                rctx->tqflag = TQ0_TYPE_CTRL;
                rctx->tqflag |= TQ1_CIPHER;
                ecb->control.op_mode = rctx->op_dir;
                ecb->control.cipher_algorithm = ECB_AES;
                ecb->cipher.header_len = 0;
                ecb->cipher.algorithm_len = areq->cryptlen;
                cpu_to_be32_array((__be32 *)ecb->key, (u32 *)op->key, op->keylen / 4);
                rctx->h = &ecb->cipher;

                rctx->tqflag |= TQ4_KEY0;
                rctx->tqflag |= TQ5_KEY4;
                rctx->tqflag |= TQ6_KEY6;
                ecb->control.aesnk = op->keylen / 4;
                break;
        }

        rctx->nr_sgs = nr_sgs;
        rctx->nr_sgd = nr_sgd;
        err = sl3516_ce_run_task(ce, rctx, crypto_tfm_alg_name(areq->base.tfm));

theend_sgs:
        if (areq->src == areq->dst) {
                dma_unmap_sg(ce->dev, areq->src, sg_nents(areq->src),
                             DMA_BIDIRECTIONAL);
        } else {
                dma_unmap_sg(ce->dev, areq->src, sg_nents(areq->src),
                             DMA_TO_DEVICE);
                dma_unmap_sg(ce->dev, areq->dst, sg_nents(areq->dst),
                             DMA_FROM_DEVICE);
        }

theend:

        return err;
}

int sl3516_ce_handle_cipher_request(struct crypto_engine *engine, void *areq)
{
        int err;
        struct skcipher_request *breq = container_of(areq, struct skcipher_request, base);

        err = sl3516_ce_cipher(breq);
        local_bh_disable();
        crypto_finalize_skcipher_request(engine, breq, err);
        local_bh_enable();

        return 0;
}

int sl3516_ce_skdecrypt(struct skcipher_request *areq)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(areq);
        struct sl3516_ce_cipher_tfm_ctx *op = crypto_skcipher_ctx(tfm);
        struct sl3516_ce_cipher_req_ctx *rctx = skcipher_request_ctx(areq);
        struct crypto_engine *engine;

        memset(rctx, 0, sizeof(struct sl3516_ce_cipher_req_ctx));
        rctx->op_dir = CE_DECRYPTION;

        if (sl3516_ce_need_fallback(areq))
                return sl3516_ce_cipher_fallback(areq);

        engine = op->ce->engine;

        return crypto_transfer_skcipher_request_to_engine(engine, areq);
}

int sl3516_ce_skencrypt(struct skcipher_request *areq)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(areq);
        struct sl3516_ce_cipher_tfm_ctx *op = crypto_skcipher_ctx(tfm);
        struct sl3516_ce_cipher_req_ctx *rctx = skcipher_request_ctx(areq);
        struct crypto_engine *engine;

        memset(rctx, 0, sizeof(struct sl3516_ce_cipher_req_ctx));
        rctx->op_dir = CE_ENCRYPTION;

        if (sl3516_ce_need_fallback(areq))
                return sl3516_ce_cipher_fallback(areq);

        engine = op->ce->engine;

        return crypto_transfer_skcipher_request_to_engine(engine, areq);
}

int sl3516_ce_cipher_init(struct crypto_tfm *tfm)
{
        struct sl3516_ce_cipher_tfm_ctx *op = crypto_tfm_ctx(tfm);
        struct sl3516_ce_alg_template *algt;
        const char *name = crypto_tfm_alg_name(tfm);
        struct crypto_skcipher *sktfm = __crypto_skcipher_cast(tfm);
        struct skcipher_alg *alg = crypto_skcipher_alg(sktfm);
        int err;

        memset(op, 0, sizeof(struct sl3516_ce_cipher_tfm_ctx));

        algt = container_of(alg, struct sl3516_ce_alg_template, alg.skcipher.base);
        op->ce = algt->ce;

        op->fallback_tfm = crypto_alloc_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK);
        if (IS_ERR(op->fallback_tfm)) {
                dev_err(op->ce->dev, "ERROR: Cannot allocate fallback for %s %ld\n",
                        name, PTR_ERR(op->fallback_tfm));
                return PTR_ERR(op->fallback_tfm);
        }

        crypto_skcipher_set_reqsize(sktfm, sizeof(struct sl3516_ce_cipher_req_ctx) +
                                    crypto_skcipher_reqsize(op->fallback_tfm));

        dev_info(op->ce->dev, "Fallback for %s is %s\n",
                 crypto_tfm_alg_driver_name(&sktfm->base),
                 crypto_tfm_alg_driver_name(crypto_skcipher_tfm(op->fallback_tfm)));

        err = pm_runtime_get_sync(op->ce->dev);
        if (err < 0)
                goto error_pm;

        return 0;
error_pm:
        pm_runtime_put_noidle(op->ce->dev);
        crypto_free_skcipher(op->fallback_tfm);
        return err;
}

void sl3516_ce_cipher_exit(struct crypto_tfm *tfm)
{
        struct sl3516_ce_cipher_tfm_ctx *op = crypto_tfm_ctx(tfm);

        kfree_sensitive(op->key);
        crypto_free_skcipher(op->fallback_tfm);
        pm_runtime_put_sync_suspend(op->ce->dev);
}

int sl3516_ce_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
                         unsigned int keylen)
{
        struct sl3516_ce_cipher_tfm_ctx *op = crypto_skcipher_ctx(tfm);
        struct sl3516_ce_dev *ce = op->ce;

        switch (keylen) {
        case 128 / 8:
                break;
        case 192 / 8:
                break;
        case 256 / 8:
                break;
        default:
                dev_dbg(ce->dev, "ERROR: Invalid keylen %u\n", keylen);
                return -EINVAL;
        }
        kfree_sensitive(op->key);
        op->keylen = keylen;
        op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
        if (!op->key)
                return -ENOMEM;

        crypto_skcipher_clear_flags(op->fallback_tfm, CRYPTO_TFM_REQ_MASK);
        crypto_skcipher_set_flags(op->fallback_tfm, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);

        return crypto_skcipher_setkey(op->fallback_tfm, key, keylen);
}