drivers/char/hw_random/exynos-rng.c

   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
  39 struct exynos_rng {
  40         struct device *dev;
  41         struct hwrng rng;
  42         void __iomem *mem;
  43         struct clk *clk;
  44 };
  45
  46 static u32 exynos_rng_readl(struct exynos_rng *rng, u32 offset)
  47 {
  48         return  __raw_readl(rng->mem + offset);
  49 }
  50
  51 static void exynos_rng_writel(struct exynos_rng *rng, u32 val, u32 offset)
  52 {
  53         __raw_writel(val, rng->mem + offset);
  54 }
  55
  56 static int exynos_rng_configure(struct exynos_rng *exynos_rng)
  57 {
  58         int i;
  59         int ret = 0;
  60
  61         for (i = 0 ; i < 5 ; i++)
  62                 exynos_rng_writel(exynos_rng, jiffies,
  63                                 EXYNOS_PRNG_SEED_OFFSET + 4*i);
  64
  65         if (!(exynos_rng_readl(exynos_rng, EXYNOS_PRNG_STATUS_OFFSET)
  66                                                  & SEED_SETTING_DONE))
  67                 ret = -EIO;
  68
  69         return ret;
  70 }
  71
  72 static int exynos_init(struct hwrng *rng)
  73 {
  74         struct exynos_rng *exynos_rng = container_of(rng,
  75                                                 struct exynos_rng, rng);
  76         int ret = 0;
  77
  78         pm_runtime_get_sync(exynos_rng->dev);
  79         ret = exynos_rng_configure(exynos_rng);
  80         pm_runtime_put_noidle(exynos_rng->dev);
  81
  82         return ret;
  83 }
  84
  85 static int exynos_read(struct hwrng *rng, void *buf,
  86                                         size_t max, bool wait)
  87 {
  88         struct exynos_rng *exynos_rng = container_of(rng,
  89                                                 struct exynos_rng, rng);
  90         u32 *data = buf;
  91         int retry = 100;
  92
  93         pm_runtime_get_sync(exynos_rng->dev);
  94
  95         exynos_rng_writel(exynos_rng, PRNG_START, 0);
  96
  97         while (!(exynos_rng_readl(exynos_rng,
  98                         EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE) && --retry)
  99                 cpu_relax();
 100         if (!retry)
 101                 return -ETIMEDOUT;
 102
 103         exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);
 104
 105         *data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET);
 106
 107         pm_runtime_mark_last_busy(exynos_rng->dev);
 108         pm_runtime_put_sync_autosuspend(exynos_rng->dev);
 109
 110         return 4;
 111 }
 112
 113 static int exynos_rng_probe(struct platform_device *pdev)
 114 {
 115         struct exynos_rng *exynos_rng;
 116         struct resource *res;
 117
 118         exynos_rng = devm_kzalloc(&pdev->dev, sizeof(struct exynos_rng),
 119                                         GFP_KERNEL);
 120         if (!exynos_rng)
 121                 return -ENOMEM;
 122
 123         exynos_rng->dev = &pdev->dev;
 124         exynos_rng->rng.name = "exynos";
 125         exynos_rng->rng.init =  exynos_init;
 126         exynos_rng->rng.read = exynos_read;
 127         exynos_rng->clk = devm_clk_get(&pdev->dev, "secss");
 128         if (IS_ERR(exynos_rng->clk)) {
 129                 dev_err(&pdev->dev, "Couldn't get clock.\n");
 130                 return -ENOENT;
 131         }
 132
 133         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 134         exynos_rng->mem = devm_ioremap_resource(&pdev->dev, res);
 135         if (IS_ERR(exynos_rng->mem))
 136                 return PTR_ERR(exynos_rng->mem);
 137
 138         platform_set_drvdata(pdev, exynos_rng);
 139
 140         pm_runtime_set_autosuspend_delay(&pdev->dev, EXYNOS_AUTOSUSPEND_DELAY);
 141         pm_runtime_use_autosuspend(&pdev->dev);
 142         pm_runtime_enable(&pdev->dev);
 143
 144         return devm_hwrng_register(&pdev->dev, &exynos_rng->rng);
 145 }
 146
 147 #ifdef CONFIG_PM
 148 static int exynos_rng_runtime_suspend(struct device *dev)
 149 {
 150         struct platform_device *pdev = to_platform_device(dev);
 151         struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
 152
 153         clk_disable_unprepare(exynos_rng->clk);
 154
 155         return 0;
 156 }
 157
 158 static int exynos_rng_runtime_resume(struct device *dev)
 159 {
 160         struct platform_device *pdev = to_platform_device(dev);
 161         struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
 162
 163         return clk_prepare_enable(exynos_rng->clk);
 164 }
 165
 166 static int exynos_rng_suspend(struct device *dev)
 167 {
 168         return pm_runtime_force_suspend(dev);
 169 }
 170
 171 static int exynos_rng_resume(struct device *dev)
 172 {
 173         struct platform_device *pdev = to_platform_device(dev);
 174         struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
 175         int ret;
 176
 177         ret = pm_runtime_force_resume(dev);
 178         if (ret)
 179                 return ret;
 180
 181         return exynos_rng_configure(exynos_rng);
 182 }
 183 #endif
 184
 185 static const struct dev_pm_ops exynos_rng_pm_ops = {
 186         SET_SYSTEM_SLEEP_PM_OPS(exynos_rng_suspend, exynos_rng_resume)
 187         SET_RUNTIME_PM_OPS(exynos_rng_runtime_suspend,
 188                            exynos_rng_runtime_resume, NULL)
 189 };
 190
 191 static const struct of_device_id exynos_rng_dt_match[] = {
 192         {
 193                 .compatible = "samsung,exynos4-rng",
 194         },
 195         { },
 196 };
 197 MODULE_DEVICE_TABLE(of, exynos_rng_dt_match);
 198
 199 static struct platform_driver exynos_rng_driver = {
 200         .driver         = {
 201                 .name   = "exynos-rng",
 202                 .pm     = &exynos_rng_pm_ops,
 203                 .of_match_table = exynos_rng_dt_match,
 204         },
 205         .probe          = exynos_rng_probe,
 206 };
 207
 208 module_platform_driver(exynos_rng_driver);
 209
 210 MODULE_DESCRIPTION("EXYNOS 4 H/W Random Number Generator driver");
 211 MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>");
 212 MODULE_LICENSE("GPL");