1/* 2 * exynos-rng.c - Random Number Generator driver for the exynos 3 * 4 * Copyright (C) 2012 Samsung Electronics 5 * Jonghwa Lee <jonghwa3.lee@smasung.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19 * 20 */ 21 22#include <linux/hw_random.h> 23#include <linux/kernel.h> 24#include <linux/module.h> 25#include <linux/io.h> 26#include <linux/platform_device.h> 27#include <linux/clk.h> 28#include <linux/pm_runtime.h> 29#include <linux/err.h> 30 31#define EXYNOS_PRNG_STATUS_OFFSET 0x10 32#define EXYNOS_PRNG_SEED_OFFSET 0x140 33#define EXYNOS_PRNG_OUT1_OFFSET 0x160 34#define SEED_SETTING_DONE BIT(1) 35#define PRNG_START 0x18 36#define PRNG_DONE BIT(5) 37#define EXYNOS_AUTOSUSPEND_DELAY 100 38 39struct exynos_rng { 40 struct device *dev; 41 struct hwrng rng; 42 void __iomem *mem; 43 struct clk *clk; 44}; 45 46static u32 exynos_rng_readl(struct exynos_rng *rng, u32 offset) 47{ 48 return __raw_readl(rng->mem + offset); 49} 50 51static void exynos_rng_writel(struct exynos_rng *rng, u32 val, u32 offset) 52{ 53 __raw_writel(val, rng->mem + offset); 54} 55 56static int exynos_init(struct hwrng *rng) 57{ 58 struct exynos_rng *exynos_rng = container_of(rng, 59 struct exynos_rng, rng); 60 int i; 61 int ret = 0; 62 63 pm_runtime_get_sync(exynos_rng->dev); 64 65 for (i = 0 ; i < 5 ; i++) 66 exynos_rng_writel(exynos_rng, jiffies, 67 EXYNOS_PRNG_SEED_OFFSET + 4*i); 68 69 if (!(exynos_rng_readl(exynos_rng, EXYNOS_PRNG_STATUS_OFFSET) 70 & SEED_SETTING_DONE)) 71 ret = -EIO; 72 73 pm_runtime_put_noidle(exynos_rng->dev); 74 75 return ret; 76} 77 78static int exynos_read(struct hwrng *rng, void *buf, 79 size_t max, bool wait) 80{ 81 struct exynos_rng *exynos_rng = container_of(rng, 82 struct exynos_rng, rng); 83 u32 *data = buf; 84 85 pm_runtime_get_sync(exynos_rng->dev); 86 87 exynos_rng_writel(exynos_rng, PRNG_START, 0); 88 89 while (!(exynos_rng_readl(exynos_rng, 90 EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE)) 91 cpu_relax(); 92 93 exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET); 94 95 *data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET); 96 97 pm_runtime_mark_last_busy(exynos_rng->dev); 98 pm_runtime_autosuspend(exynos_rng->dev); 99 100 return 4; 101} 102 103static int exynos_rng_probe(struct platform_device *pdev) 104{ 105 struct exynos_rng *exynos_rng; 106 struct resource *res; 107 108 exynos_rng = devm_kzalloc(&pdev->dev, sizeof(struct exynos_rng), 109 GFP_KERNEL); 110 if (!exynos_rng) 111 return -ENOMEM; 112 113 exynos_rng->dev = &pdev->dev; 114 exynos_rng->rng.name = "exynos"; 115 exynos_rng->rng.init = exynos_init; 116 exynos_rng->rng.read = exynos_read; 117 exynos_rng->clk = devm_clk_get(&pdev->dev, "secss"); 118 if (IS_ERR(exynos_rng->clk)) { 119 dev_err(&pdev->dev, "Couldn't get clock.\n"); 120 return -ENOENT; 121 } 122 123 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 124 exynos_rng->mem = devm_ioremap_resource(&pdev->dev, res); 125 if (IS_ERR(exynos_rng->mem)) 126 return PTR_ERR(exynos_rng->mem); 127 128 platform_set_drvdata(pdev, exynos_rng); 129 130 pm_runtime_set_autosuspend_delay(&pdev->dev, EXYNOS_AUTOSUSPEND_DELAY); 131 pm_runtime_use_autosuspend(&pdev->dev); 132 pm_runtime_enable(&pdev->dev); 133 134 return hwrng_register(&exynos_rng->rng); 135} 136 137static int exynos_rng_remove(struct platform_device *pdev) 138{ 139 struct exynos_rng *exynos_rng = platform_get_drvdata(pdev); 140 141 hwrng_unregister(&exynos_rng->rng); 142 143 return 0; 144} 145 146#if defined(CONFIG_PM_SLEEP) || defined(CONFIG_PM_RUNTIME) 147static int exynos_rng_runtime_suspend(struct device *dev) 148{ 149 struct platform_device *pdev = to_platform_device(dev); 150 struct exynos_rng *exynos_rng = platform_get_drvdata(pdev); 151 152 clk_disable_unprepare(exynos_rng->clk); 153 154 return 0; 155} 156 157static int exynos_rng_runtime_resume(struct device *dev) 158{ 159 struct platform_device *pdev = to_platform_device(dev); 160 struct exynos_rng *exynos_rng = platform_get_drvdata(pdev); 161 162 return clk_prepare_enable(exynos_rng->clk); 163} 164#endif 165 166static UNIVERSAL_DEV_PM_OPS(exynos_rng_pm_ops, exynos_rng_runtime_suspend, 167 exynos_rng_runtime_resume, NULL); 168 169static struct platform_driver exynos_rng_driver = { 170 .driver = { 171 .name = "exynos-rng", 172 .owner = THIS_MODULE, 173 .pm = &exynos_rng_pm_ops, 174 }, 175 .probe = exynos_rng_probe, 176 .remove = exynos_rng_remove, 177}; 178 179module_platform_driver(exynos_rng_driver); 180 181MODULE_DESCRIPTION("EXYNOS 4 H/W Random Number Generator driver"); 182MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>"); 183MODULE_LICENSE("GPL"); 184