drivers/char/hw_random/omap-rng.c

   1 /*
   2  * omap-rng.c - RNG driver for TI OMAP CPU family
   3  *
   4  * Author: Deepak Saxena <dsaxena@plexity.net>
   5  *
   6  * Copyright 2005 (c) MontaVista Software, Inc.
   7  *
   8  * Mostly based on original driver:
   9  *
  10  * Copyright (C) 2005 Nokia Corporation
  11  * Author: Juha Yrjölä <juha.yrjola@nokia.com>
  12  *
  13  * This file is licensed under  the terms of the GNU General Public
  14  * License version 2. This program is licensed "as is" without any
  15  * warranty of any kind, whether express or implied.
  16  */
  17
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/random.h>
  21 #include <linux/err.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/hw_random.h>
  24 #include <linux/delay.h>
  25 #include <linux/slab.h>
  26 #include <linux/pm_runtime.h>
  27
  28 #include <asm/io.h>
  29
  30 #define RNG_OUT_REG             0x00            /* Output register */
  31 #define RNG_STAT_REG            0x04            /* Status register
  32                                                         [0] = STAT_BUSY */
  33 #define RNG_ALARM_REG           0x24            /* Alarm register
  34                                                         [7:0] = ALARM_COUNTER */
  35 #define RNG_CONFIG_REG          0x28            /* Configuration register
  36                                                         [11:6] = RESET_COUNT
  37                                                         [5:3]  = RING2_DELAY
  38                                                         [2:0]  = RING1_DELAY */
  39 #define RNG_REV_REG             0x3c            /* Revision register
  40                                                         [7:0] = REV_NB */
  41 #define RNG_MASK_REG            0x40            /* Mask and reset register
  42                                                         [2] = IT_EN
  43                                                         [1] = SOFTRESET
  44                                                         [0] = AUTOIDLE */
  45 #define RNG_SYSSTATUS           0x44            /* System status
  46                                                         [0] = RESETDONE */
  47
  48 /**
  49  * struct omap_rng_private_data - RNG IP block-specific data
  50  * @base: virtual address of the beginning of the RNG IP block registers
  51  * @mem_res: struct resource * for the IP block registers physical memory
  52  */
  53 struct omap_rng_private_data {
  54         void __iomem *base;
  55         struct resource *mem_res;
  56 };
  57
  58 static inline u32 omap_rng_read_reg(struct omap_rng_private_data *priv, int reg)
  59 {
  60         return __raw_readl(priv->base + reg);
  61 }
  62
  63 static inline void omap_rng_write_reg(struct omap_rng_private_data *priv,
  64                                       int reg, u32 val)
  65 {
  66         __raw_writel(val, priv->base + reg);
  67 }
  68
  69 static int omap_rng_data_present(struct hwrng *rng, int wait)
  70 {
  71         struct omap_rng_private_data *priv;
  72         int data, i;
  73
  74         priv = (struct omap_rng_private_data *)rng->priv;
  75
  76         for (i = 0; i < 20; i++) {
  77                 data = omap_rng_read_reg(priv, RNG_STAT_REG) ? 0 : 1;
  78                 if (data || !wait)
  79                         break;
  80                 /* RNG produces data fast enough (2+ MBit/sec, even
  81                  * during "rngtest" loads, that these delays don't
  82                  * seem to trigger.  We *could* use the RNG IRQ, but
  83                  * that'd be higher overhead ... so why bother?
  84                  */
  85                 udelay(10);
  86         }
  87         return data;
  88 }
  89
  90 static int omap_rng_data_read(struct hwrng *rng, u32 *data)
  91 {
  92         struct omap_rng_private_data *priv;
  93
  94         priv = (struct omap_rng_private_data *)rng->priv;
  95
  96         *data = omap_rng_read_reg(priv, RNG_OUT_REG);
  97
  98         return sizeof(u32);
  99 }
 100
 101 static struct hwrng omap_rng_ops = {
 102         .name           = "omap",
 103         .data_present   = omap_rng_data_present,
 104         .data_read      = omap_rng_data_read,
 105 };
 106
 107 static int omap_rng_probe(struct platform_device *pdev)
 108 {
 109         struct omap_rng_private_data *priv;
 110         int ret;
 111
 112         priv = devm_kzalloc(&pdev->dev, sizeof(struct omap_rng_private_data),
 113                             GFP_KERNEL);
 114         if (!priv) {
 115                 dev_err(&pdev->dev, "could not allocate memory\n");
 116                 return -ENOMEM;
 117         };
 118
 119         omap_rng_ops.priv = (unsigned long)priv;
 120         platform_set_drvdata(pdev, priv);
 121
 122         priv->mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 123         priv->base = devm_ioremap_resource(&pdev->dev, priv->mem_res);
 124         if (IS_ERR(priv->base)) {
 125                 ret = PTR_ERR(priv->base);
 126                 goto err_ioremap;
 127         }
 128
 129         pm_runtime_enable(&pdev->dev);
 130         pm_runtime_get_sync(&pdev->dev);
 131
 132         ret = hwrng_register(&omap_rng_ops);
 133         if (ret)
 134                 goto err_register;
 135
 136         dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n",
 137                  omap_rng_read_reg(priv, RNG_REV_REG));
 138
 139         omap_rng_write_reg(priv, RNG_MASK_REG, 0x1);
 140
 141         return 0;
 142
 143 err_register:
 144         priv->base = NULL;
 145         pm_runtime_disable(&pdev->dev);
 146 err_ioremap:
 147         return ret;
 148 }
 149
 150 static int __exit omap_rng_remove(struct platform_device *pdev)
 151 {
 152         struct omap_rng_private_data *priv = platform_get_drvdata(pdev);
 153
 154         hwrng_unregister(&omap_rng_ops);
 155
 156         omap_rng_write_reg(priv, RNG_MASK_REG, 0x0);
 157
 158         pm_runtime_put_sync(&pdev->dev);
 159         pm_runtime_disable(&pdev->dev);
 160
 161         return 0;
 162 }
 163
 164 #ifdef CONFIG_PM_SLEEP
 165
 166 static int omap_rng_suspend(struct device *dev)
 167 {
 168         struct omap_rng_private_data *priv = dev_get_drvdata(dev);
 169
 170         omap_rng_write_reg(priv, RNG_MASK_REG, 0x0);
 171         pm_runtime_put_sync(dev);
 172
 173         return 0;
 174 }
 175
 176 static int omap_rng_resume(struct device *dev)
 177 {
 178         struct omap_rng_private_data *priv = dev_get_drvdata(dev);
 179
 180         pm_runtime_get_sync(dev);
 181         omap_rng_write_reg(priv, RNG_MASK_REG, 0x1);
 182
 183         return 0;
 184 }
 185
 186 static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);
 187 #define OMAP_RNG_PM     (&omap_rng_pm)
 188
 189 #else
 190
 191 #define OMAP_RNG_PM     NULL
 192
 193 #endif
 194
 195 static struct platform_driver omap_rng_driver = {
 196         .driver = {
 197                 .name           = "omap_rng",
 198                 .owner          = THIS_MODULE,
 199                 .pm             = OMAP_RNG_PM,
 200         },
 201         .probe          = omap_rng_probe,
 202         .remove         = __exit_p(omap_rng_remove),
 203 };
 204
 205 module_platform_driver(omap_rng_driver);
 206 MODULE_ALIAS("platform:omap_rng");
 207 MODULE_AUTHOR("Deepak Saxena (and others)");
 208 MODULE_LICENSE("GPL");