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/clk.h>
  22 #include <linux/err.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/hw_random.h>
  25 #include <linux/delay.h>
  26
  27 #include <asm/io.h>
  28
  29 #define RNG_OUT_REG             0x00            /* Output register */
  30 #define RNG_STAT_REG            0x04            /* Status register
  31                                                         [0] = STAT_BUSY */
  32 #define RNG_ALARM_REG           0x24            /* Alarm register
  33                                                         [7:0] = ALARM_COUNTER */
  34 #define RNG_CONFIG_REG          0x28            /* Configuration register
  35                                                         [11:6] = RESET_COUNT
  36                                                         [5:3]  = RING2_DELAY
  37                                                         [2:0]  = RING1_DELAY */
  38 #define RNG_REV_REG             0x3c            /* Revision register
  39                                                         [7:0] = REV_NB */
  40 #define RNG_MASK_REG            0x40            /* Mask and reset register
  41                                                         [2] = IT_EN
  42                                                         [1] = SOFTRESET
  43                                                         [0] = AUTOIDLE */
  44 #define RNG_SYSSTATUS           0x44            /* System status
  45                                                         [0] = RESETDONE */
  46
  47 static void __iomem *rng_base;
  48 static struct clk *rng_ick;
  49 static struct platform_device *rng_dev;
  50
  51 static inline u32 omap_rng_read_reg(int reg)
  52 {
  53         return __raw_readl(rng_base + reg);
  54 }
  55
  56 static inline void omap_rng_write_reg(int reg, u32 val)
  57 {
  58         __raw_writel(val, rng_base + reg);
  59 }
  60
  61 static int omap_rng_data_present(struct hwrng *rng, int wait)
  62 {
  63         int data, i;
  64
  65         for (i = 0; i < 20; i++) {
  66                 data = omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1;
  67                 if (data || !wait)
  68                         break;
  69                 /* RNG produces data fast enough (2+ MBit/sec, even
  70                  * during "rngtest" loads, that these delays don't
  71                  * seem to trigger.  We *could* use the RNG IRQ, but
  72                  * that'd be higher overhead ... so why bother?
  73                  */
  74                 udelay(10);
  75         }
  76         return data;
  77 }
  78
  79 static int omap_rng_data_read(struct hwrng *rng, u32 *data)
  80 {
  81         *data = omap_rng_read_reg(RNG_OUT_REG);
  82
  83         return 4;
  84 }
  85
  86 static struct hwrng omap_rng_ops = {
  87         .name           = "omap",
  88         .data_present   = omap_rng_data_present,
  89         .data_read      = omap_rng_data_read,
  90 };
  91
  92 static int __devinit omap_rng_probe(struct platform_device *pdev)
  93 {
  94         struct resource *res;
  95         int ret;
  96
  97         /*
  98          * A bit ugly, and it will never actually happen but there can
  99          * be only one RNG and this catches any bork
 100          */
 101         if (rng_dev)
 102                 return -EBUSY;
 103
 104         if (cpu_is_omap24xx()) {
 105                 rng_ick = clk_get(&pdev->dev, "ick");
 106                 if (IS_ERR(rng_ick)) {
 107                         dev_err(&pdev->dev, "Could not get rng_ick\n");
 108                         ret = PTR_ERR(rng_ick);
 109                         return ret;
 110                 } else
 111                         clk_enable(rng_ick);
 112         }
 113
 114         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 115
 116         if (!res)
 117                 return -ENOENT;
 118
 119         if (!request_mem_region(res->start, resource_size(res), pdev->name)) {
 120                 ret = -EBUSY;
 121                 goto err_region;
 122         }
 123
 124         dev_set_drvdata(&pdev->dev, res);
 125         rng_base = ioremap(res->start, resource_size(res));
 126         if (!rng_base) {
 127                 ret = -ENOMEM;
 128                 goto err_ioremap;
 129         }
 130
 131         ret = hwrng_register(&omap_rng_ops);
 132         if (ret)
 133                 goto err_register;
 134
 135         dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n",
 136                 omap_rng_read_reg(RNG_REV_REG));
 137         omap_rng_write_reg(RNG_MASK_REG, 0x1);
 138
 139         rng_dev = pdev;
 140
 141         return 0;
 142
 143 err_register:
 144         iounmap(rng_base);
 145         rng_base = NULL;
 146 err_ioremap:
 147         release_mem_region(res->start, resource_size(res));
 148 err_region:
 149         if (cpu_is_omap24xx()) {
 150                 clk_disable(rng_ick);
 151                 clk_put(rng_ick);
 152         }
 153         return ret;
 154 }
 155
 156 static int __exit omap_rng_remove(struct platform_device *pdev)
 157 {
 158         struct resource *res = dev_get_drvdata(&pdev->dev);
 159
 160         hwrng_unregister(&omap_rng_ops);
 161
 162         omap_rng_write_reg(RNG_MASK_REG, 0x0);
 163
 164         iounmap(rng_base);
 165
 166         if (cpu_is_omap24xx()) {
 167                 clk_disable(rng_ick);
 168                 clk_put(rng_ick);
 169         }
 170
 171         release_mem_region(res->start, resource_size(res));
 172         rng_base = NULL;
 173
 174         return 0;
 175 }
 176
 177 #ifdef CONFIG_PM
 178
 179 static int omap_rng_suspend(struct platform_device *pdev, pm_message_t message)
 180 {
 181         omap_rng_write_reg(RNG_MASK_REG, 0x0);
 182         return 0;
 183 }
 184
 185 static int omap_rng_resume(struct platform_device *pdev)
 186 {
 187         omap_rng_write_reg(RNG_MASK_REG, 0x1);
 188         return 0;
 189 }
 190
 191 #else
 192
 193 #define omap_rng_suspend        NULL
 194 #define omap_rng_resume         NULL
 195
 196 #endif
 197
 198 /* work with hotplug and coldplug */
 199 MODULE_ALIAS("platform:omap_rng");
 200
 201 static struct platform_driver omap_rng_driver = {
 202         .driver = {
 203                 .name           = "omap_rng",
 204                 .owner          = THIS_MODULE,
 205         },
 206         .probe          = omap_rng_probe,
 207         .remove         = __exit_p(omap_rng_remove),
 208         .suspend        = omap_rng_suspend,
 209         .resume         = omap_rng_resume
 210 };
 211
 212 static int __init omap_rng_init(void)
 213 {
 214         if (!cpu_is_omap16xx() && !cpu_is_omap24xx())
 215                 return -ENODEV;
 216
 217         return platform_driver_register(&omap_rng_driver);
 218 }
 219
 220 static void __exit omap_rng_exit(void)
 221 {
 222         platform_driver_unregister(&omap_rng_driver);
 223 }
 224
 225 module_init(omap_rng_init);
 226 module_exit(omap_rng_exit);
 227
 228 MODULE_AUTHOR("Deepak Saxena (and others)");
 229 MODULE_LICENSE("GPL");