drivers/char/hw_random/omap-rng.c

   1 /*
   2  * drivers/char/hw_random/omap-rng.c
   3  *
   4  * RNG driver for TI OMAP CPU family
   5  *
   6  * Author: Deepak Saxena <dsaxena@plexity.net>
   7  *
   8  * Copyright 2005 (c) MontaVista Software, Inc.
   9  *
  10  * Mostly based on original driver:
  11  *
  12  * Copyright (C) 2005 Nokia Corporation
  13  * Author: Juha Yrj��<juha.yrjola@nokia.com>
  14  *
  15  * This file is licensed under  the terms of the GNU General Public
  16  * License version 2. This program is licensed "as is" without any
  17  * warranty of any kind, whether express or implied.
  18  *
  19  * TODO:
  20  *
  21  * - Make status updated be interrupt driven so we don't poll
  22  *
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/init.h>
  27 #include <linux/random.h>
  28 #include <linux/clk.h>
  29 #include <linux/err.h>
  30 #include <linux/platform_device.h>
  31 #include <linux/hw_random.h>
  32
  33 #include <asm/io.h>
  34
  35 #define RNG_OUT_REG             0x00            /* Output register */
  36 #define RNG_STAT_REG            0x04            /* Status register
  37                                                         [0] = STAT_BUSY */
  38 #define RNG_ALARM_REG           0x24            /* Alarm register
  39                                                         [7:0] = ALARM_COUNTER */
  40 #define RNG_CONFIG_REG          0x28            /* Configuration register
  41                                                         [11:6] = RESET_COUNT
  42                                                         [5:3]  = RING2_DELAY
  43                                                         [2:0]  = RING1_DELAY */
  44 #define RNG_REV_REG             0x3c            /* Revision register
  45                                                         [7:0] = REV_NB */
  46 #define RNG_MASK_REG            0x40            /* Mask and reset register
  47                                                         [2] = IT_EN
  48                                                         [1] = SOFTRESET
  49                                                         [0] = AUTOIDLE */
  50 #define RNG_SYSSTATUS           0x44            /* System status
  51                                                         [0] = RESETDONE */
  52
  53 static void __iomem *rng_base;
  54 static struct clk *rng_ick;
  55 static struct platform_device *rng_dev;
  56
  57 static u32 omap_rng_read_reg(int reg)
  58 {
  59         return __raw_readl(rng_base + reg);
  60 }
  61
  62 static void omap_rng_write_reg(int reg, u32 val)
  63 {
  64         __raw_writel(val, rng_base + reg);
  65 }
  66
  67 /* REVISIT: Does the status bit really work on 16xx? */
  68 static int omap_rng_data_present(struct hwrng *rng)
  69 {
  70         return omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1;
  71 }
  72
  73 static int omap_rng_data_read(struct hwrng *rng, u32 *data)
  74 {
  75         *data = omap_rng_read_reg(RNG_OUT_REG);
  76
  77         return 4;
  78 }
  79
  80 static struct hwrng omap_rng_ops = {
  81         .name           = "omap",
  82         .data_present   = omap_rng_data_present,
  83         .data_read      = omap_rng_data_read,
  84 };
  85
  86 static int __init omap_rng_probe(struct platform_device *pdev)
  87 {
  88         struct resource *res, *mem;
  89         int ret;
  90
  91         /*
  92          * A bit ugly, and it will never actually happen but there can
  93          * be only one RNG and this catches any bork
  94          */
  95         BUG_ON(rng_dev);
  96
  97         if (cpu_is_omap24xx()) {
  98                 rng_ick = clk_get(NULL, "rng_ick");
  99                 if (IS_ERR(rng_ick)) {
 100                         dev_err(&pdev->dev, "Could not get rng_ick\n");
 101                         ret = PTR_ERR(rng_ick);
 102                         return ret;
 103                 } else
 104                         clk_enable(rng_ick);
 105         }
 106
 107         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 108
 109         if (!res)
 110                 return -ENOENT;
 111
 112         mem = request_mem_region(res->start, res->end - res->start + 1,
 113                                  pdev->name);
 114         if (mem == NULL)
 115                 return -EBUSY;
 116
 117         dev_set_drvdata(&pdev->dev, mem);
 118         rng_base = (u32 __iomem *)io_p2v(res->start);
 119
 120         ret = hwrng_register(&omap_rng_ops);
 121         if (ret) {
 122                 release_resource(mem);
 123                 rng_base = NULL;
 124                 return ret;
 125         }
 126
 127         dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n",
 128                 omap_rng_read_reg(RNG_REV_REG));
 129         omap_rng_write_reg(RNG_MASK_REG, 0x1);
 130
 131         rng_dev = pdev;
 132
 133         return 0;
 134 }
 135
 136 static int __exit omap_rng_remove(struct platform_device *pdev)
 137 {
 138         struct resource *mem = dev_get_drvdata(&pdev->dev);
 139
 140         hwrng_unregister(&omap_rng_ops);
 141
 142         omap_rng_write_reg(RNG_MASK_REG, 0x0);
 143
 144         if (cpu_is_omap24xx()) {
 145                 clk_disable(rng_ick);
 146                 clk_put(rng_ick);
 147         }
 148
 149         release_resource(mem);
 150         rng_base = NULL;
 151
 152         return 0;
 153 }
 154
 155 #ifdef CONFIG_PM
 156
 157 static int omap_rng_suspend(struct platform_device *pdev, pm_message_t message)
 158 {
 159         omap_rng_write_reg(RNG_MASK_REG, 0x0);
 160         return 0;
 161 }
 162
 163 static int omap_rng_resume(struct platform_device *pdev)
 164 {
 165         omap_rng_write_reg(RNG_MASK_REG, 0x1);
 166         return 0;
 167 }
 168
 169 #else
 170
 171 #define omap_rng_suspend        NULL
 172 #define omap_rng_resume         NULL
 173
 174 #endif
 175
 176
 177 static struct platform_driver omap_rng_driver = {
 178         .driver = {
 179                 .name           = "omap_rng",
 180                 .owner          = THIS_MODULE,
 181         },
 182         .probe          = omap_rng_probe,
 183         .remove         = __exit_p(omap_rng_remove),
 184         .suspend        = omap_rng_suspend,
 185         .resume         = omap_rng_resume
 186 };
 187
 188 static int __init omap_rng_init(void)
 189 {
 190         if (!cpu_is_omap16xx() && !cpu_is_omap24xx())
 191                 return -ENODEV;
 192
 193         return platform_driver_register(&omap_rng_driver);
 194 }
 195
 196 static void __exit omap_rng_exit(void)
 197 {
 198         platform_driver_unregister(&omap_rng_driver);
 199 }
 200
 201 module_init(omap_rng_init);
 202 module_exit(omap_rng_exit);
 203
 204 MODULE_AUTHOR("Deepak Saxena (and others)");
 205 MODULE_LICENSE("GPL");