drivers/crypto/allwinner/sun8i-ce/sun8i-ce-trng.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * sun8i-ce-trng.c - hardware cryptographic offloader for
   4  * Allwinner H3/A64/H5/H2+/H6/R40 SoC
   5  *
   6  * Copyright (C) 2015-2020 Corentin Labbe <clabbe@baylibre.com>
   7  *
   8  * This file handle the TRNG
   9  *
  10  * You could find a link for the datasheet in Documentation/arch/arm/sunxi.rst
  11  */
  12 #include "sun8i-ce.h"
  13 #include <linux/dma-mapping.h>
  14 #include <linux/pm_runtime.h>
  15 #include <linux/hw_random.h>
  16 /*
  17  * Note that according to the algorithm ID, 2 versions of the TRNG exists,
  18  * The first present in H3/H5/R40/A64 and the second present in H6.
  19  * This file adds support for both, but only the second is working
  20  * reliabily according to rngtest.
  21  **/
  22
  23 static int sun8i_ce_trng_read(struct hwrng *rng, void *data, size_t max, bool wait)
  24 {
  25         struct sun8i_ce_dev *ce;
  26         dma_addr_t dma_dst;
  27         int err = 0;
  28         int flow = 3;
  29         unsigned int todo;
  30         struct sun8i_ce_flow *chan;
  31         struct ce_task *cet;
  32         u32 common;
  33         void *d;
  34
  35         ce = container_of(rng, struct sun8i_ce_dev, trng);
  36
  37         /* round the data length to a multiple of 32*/
  38         todo = max + 32;
  39         todo -= todo % 32;
  40
  41         d = kzalloc(todo, GFP_KERNEL | GFP_DMA);
  42         if (!d)
  43                 return -ENOMEM;
  44
  45 #ifdef CONFIG_CRYPTO_DEV_SUN8I_CE_DEBUG
  46         ce->hwrng_stat_req++;
  47         ce->hwrng_stat_bytes += todo;
  48 #endif
  49
  50         dma_dst = dma_map_single(ce->dev, d, todo, DMA_FROM_DEVICE);
  51         if (dma_mapping_error(ce->dev, dma_dst)) {
  52                 dev_err(ce->dev, "Cannot DMA MAP DST\n");
  53                 err = -EFAULT;
  54                 goto err_dst;
  55         }
  56
  57         err = pm_runtime_resume_and_get(ce->dev);
  58         if (err < 0)
  59                 goto err_pm;
  60
  61         mutex_lock(&ce->rnglock);
  62         chan = &ce->chanlist[flow];
  63
  64         cet = &chan->tl[0];
  65         memset(cet, 0, sizeof(struct ce_task));
  66
  67         cet->t_id = cpu_to_le32(flow);
  68         common = ce->variant->trng | CE_COMM_INT;
  69         cet->t_common_ctl = cpu_to_le32(common);
  70
  71         /* recent CE (H6) need length in bytes, in word otherwise */
  72         if (ce->variant->trng_t_dlen_in_bytes)
  73                 cet->t_dlen = cpu_to_le32(todo);
  74         else
  75                 cet->t_dlen = cpu_to_le32(todo / 4);
  76
  77         cet->t_sym_ctl = 0;
  78         cet->t_asym_ctl = 0;
  79
  80         cet->t_dst[0].addr = cpu_to_le32(dma_dst);
  81         cet->t_dst[0].len = cpu_to_le32(todo / 4);
  82         ce->chanlist[flow].timeout = todo;
  83
  84         err = sun8i_ce_run_task(ce, 3, "TRNG");
  85         mutex_unlock(&ce->rnglock);
  86
  87         pm_runtime_put(ce->dev);
  88
  89 err_pm:
  90         dma_unmap_single(ce->dev, dma_dst, todo, DMA_FROM_DEVICE);
  91
  92         if (!err) {
  93                 memcpy(data, d, max);
  94                 err = max;
  95         }
  96 err_dst:
  97         kfree_sensitive(d);
  98         return err;
  99 }
 100
 101 int sun8i_ce_hwrng_register(struct sun8i_ce_dev *ce)
 102 {
 103         int ret;
 104
 105         if (ce->variant->trng == CE_ID_NOTSUPP) {
 106                 dev_info(ce->dev, "TRNG not supported\n");
 107                 return 0;
 108         }
 109         ce->trng.name = "sun8i Crypto Engine TRNG";
 110         ce->trng.read = sun8i_ce_trng_read;
 111
 112         ret = hwrng_register(&ce->trng);
 113         if (ret)
 114                 dev_err(ce->dev, "Fail to register the TRNG\n");
 115         return ret;
 116 }
 117
 118 void sun8i_ce_hwrng_unregister(struct sun8i_ce_dev *ce)
 119 {
 120         if (ce->variant->trng == CE_ID_NOTSUPP)
 121                 return;
 122         hwrng_unregister(&ce->trng);
 123 }