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 #include <linux/clk.h> 66 67 #define RNG_DATA 0x00 68 69 struct meson_rng_data { 70 void __iomem *base; 71 struct platform_device *pdev; 72 struct hwrng rng; 73 struct clk *core_clk; 74 }; 75 76 static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) 77 { 78 struct meson_rng_data *data = 79 container_of(rng, struct meson_rng_data, rng); 80 81 *(u32 *)buf = readl_relaxed(data->base + RNG_DATA); 82 83 return sizeof(u32); 84 } 85 86 static void meson_rng_clk_disable(void *data) 87 { 88 clk_disable_unprepare(data); 89 } 90 91 static int meson_rng_probe(struct platform_device *pdev) 92 { 93 struct device *dev = &pdev->dev; 94 struct meson_rng_data *data; 95 struct resource *res; 96 int ret; 97 98 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 99 if (!data) 100 return -ENOMEM; 101 102 data->pdev = pdev; 103 104 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 105 data->base = devm_ioremap_resource(dev, res); 106 if (IS_ERR(data->base)) 107 return PTR_ERR(data->base); 108 109 data->core_clk = devm_clk_get(dev, "core"); 110 if (IS_ERR(data->core_clk)) 111 data->core_clk = NULL; 112 113 if (data->core_clk) { 114 ret = clk_prepare_enable(data->core_clk); 115 if (ret) 116 return ret; 117 ret = devm_add_action_or_reset(dev, meson_rng_clk_disable, 118 data->core_clk); 119 if (ret) 120 return ret; 121 } 122 123 data->rng.name = pdev->name; 124 data->rng.read = meson_rng_read; 125 126 platform_set_drvdata(pdev, data); 127 128 return devm_hwrng_register(dev, &data->rng); 129 } 130 131 static const struct of_device_id meson_rng_of_match[] = { 132 { .compatible = "amlogic,meson-rng", }, 133 {}, 134 }; 135 MODULE_DEVICE_TABLE(of, meson_rng_of_match); 136 137 static struct platform_driver meson_rng_driver = { 138 .probe = meson_rng_probe, 139 .driver = { 140 .name = "meson-rng", 141 .of_match_table = meson_rng_of_match, 142 }, 143 }; 144 145 module_platform_driver(meson_rng_driver); 146 147 MODULE_DESCRIPTION("Meson H/W Random Number Generator driver"); 148 MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>"); 149 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>"); 150 MODULE_LICENSE("Dual BSD/GPL"); 151