drivers/char/hw_random/meson-rng.c

   1 /*
   2  * This file is provided under a dual BSD/GPLv2 license.  When using or
   3  * redistributing this file, you may do so under either license.
   4  *
   5  * GPL LICENSE SUMMARY
   6  *
   7  * Copyright (c) 2016 BayLibre, SAS.
   8  * Author: Neil Armstrong <narmstrong@baylibre.com>
   9  * Copyright (C) 2014 Amlogic, Inc.
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of version 2 of the GNU General Public License as
  13  * published by the Free Software Foundation.
  14  *
  15  * This program is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  22  * The full GNU General Public License is included in this distribution
  23  * in the file called COPYING.
  24  *
  25  * BSD LICENSE
  26  *
  27  * Copyright (c) 2016 BayLibre, SAS.
  28  * Author: Neil Armstrong <narmstrong@baylibre.com>
  29  * Copyright (C) 2014 Amlogic, Inc.
  30  *
  31  * Redistribution and use in source and binary forms, with or without
  32  * modification, are permitted provided that the following conditions
  33  * are met:
  34  *
  35  *   * Redistributions of source code must retain the above copyright
  36  *     notice, this list of conditions and the following disclaimer.
  37  *   * Redistributions in binary form must reproduce the above copyright
  38  *     notice, this list of conditions and the following disclaimer in
  39  *     the documentation and/or other materials provided with the
  40  *     distribution.
  41  *   * Neither the name of Intel Corporation nor the names of its
  42  *     contributors may be used to endorse or promote products derived
  43  *     from this software without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  46  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  47  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  48  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  49  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  50  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  51  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  52  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  53  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  54  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  55  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  56  */
  57 #include <linux/err.h>
  58 #include <linux/module.h>
  59 #include <linux/io.h>
  60 #include <linux/platform_device.h>
  61 #include <linux/hw_random.h>
  62 #include <linux/slab.h>
  63 #include <linux/types.h>
  64 #include <linux/of.h>
  65
  66 #define RNG_DATA 0x00
  67
  68 struct meson_rng_data {
  69         void __iomem *base;
  70         struct platform_device *pdev;
  71         struct hwrng rng;
  72 };
  73
  74 static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
  75 {
  76         struct meson_rng_data *data =
  77                         container_of(rng, struct meson_rng_data, rng);
  78
  79         if (max < sizeof(u32))
  80                 return 0;
  81
  82         *(u32 *)buf = readl_relaxed(data->base + RNG_DATA);
  83
  84         return sizeof(u32);
  85 }
  86
  87 static int meson_rng_probe(struct platform_device *pdev)
  88 {
  89         struct device *dev = &pdev->dev;
  90         struct meson_rng_data *data;
  91         struct resource *res;
  92
  93         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
  94         if (!data)
  95                 return -ENOMEM;
  96
  97         data->pdev = pdev;
  98
  99         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 100         data->base = devm_ioremap_resource(dev, res);
 101         if (IS_ERR(data->base))
 102                 return PTR_ERR(data->base);
 103
 104         data->rng.name = pdev->name;
 105         data->rng.read = meson_rng_read;
 106
 107         platform_set_drvdata(pdev, data);
 108
 109         return devm_hwrng_register(dev, &data->rng);
 110 }
 111
 112 static const struct of_device_id meson_rng_of_match[] = {
 113         { .compatible = "amlogic,meson-rng", },
 114         {},
 115 };
 116
 117 static struct platform_driver meson_rng_driver = {
 118         .probe  = meson_rng_probe,
 119         .driver = {
 120                 .name = "meson-rng",
 121                 .of_match_table = meson_rng_of_match,
 122         },
 123 };
 124
 125 module_platform_driver(meson_rng_driver);
 126
 127 MODULE_ALIAS("platform:meson-rng");
 128 MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
 129 MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
 130 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
 131 MODULE_LICENSE("Dual BSD/GPL");