drivers/char/hw_random/omap-rng.c

   1 /*
   2  * driver/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/err.h>
  29 #include <linux/device.h>
  30 #include <linux/hw_random.h>
  31
  32 #include <asm/io.h>
  33 #include <asm/hardware/clock.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 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 device *dev)
  87 {
  88         struct platform_device *pdev = to_platform_device(dev);
  89         struct resource *res, *mem;
  90         int ret;
  91
  92         /*
  93          * A bit ugly, and it will never actually happen but there can
  94          * be only one RNG and this catches any bork
  95          */
  96         BUG_ON(rng_dev);
  97
  98         if (cpu_is_omap24xx()) {
  99                 rng_ick = clk_get(NULL, "rng_ick");
 100                 if (IS_ERR(rng_ick)) {
 101                         dev_err(dev, "Could not get rng_ick\n");
 102                         ret = PTR_ERR(rng_ick);
 103                         return ret;
 104                 }
 105                 else {
 106                         clk_use(rng_ick);
 107                 }
 108         }
 109
 110         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 111
 112         if (!res)
 113                 return -ENOENT;
 114
 115         mem = request_mem_region(res->start, res->end - res->start + 1,
 116                                  pdev->name);
 117         if (mem == NULL)
 118                 return -EBUSY;
 119
 120         dev_set_drvdata(dev, mem);
 121         rng_base = (u32 __iomem *)io_p2v(res->start);
 122
 123         ret = hwrng_register(&omap_rng_ops);
 124         if (ret) {
 125                 release_resource(mem);
 126                 rng_base = NULL;
 127                 return ret;
 128         }
 129
 130         dev_info(dev, "OMAP Random Number Generator ver. %02x\n",
 131                 omap_rng_read_reg(RNG_REV_REG));
 132         omap_rng_write_reg(RNG_MASK_REG, 0x1);
 133
 134         rng_dev = dev;
 135
 136         return 0;
 137 }
 138
 139 static int __exit omap_rng_remove(struct device *dev)
 140 {
 141         struct resource *mem = dev_get_drvdata(dev);
 142
 143         hwrng_unregister(&omap_rng_ops);
 144
 145         omap_rng_write_reg(RNG_MASK_REG, 0x0);
 146
 147         if (cpu_is_omap24xx()) {
 148                 clk_unuse(rng_ick);
 149                 clk_put(rng_ick);
 150         }
 151
 152         release_resource(mem);
 153         rng_base = NULL;
 154
 155         return 0;
 156 }
 157
 158 #ifdef CONFIG_PM
 159
 160 static int omap_rng_suspend(struct device *dev, pm_message_t message, u32 level)
 161 {
 162         omap_rng_write_reg(RNG_MASK_REG, 0x0);
 163
 164         return 0;
 165 }
 166
 167 static int omap_rng_resume(struct device *dev, pm_message_t message, u32 level)
 168 {
 169         omap_rng_write_reg(RNG_MASK_REG, 0x1);
 170
 171         return 1;
 172 }
 173
 174 #else
 175
 176 #define omap_rng_suspend        NULL
 177 #define omap_rng_resume         NULL
 178
 179 #endif
 180
 181
 182 static struct device_driver omap_rng_driver = {
 183         .name           = "omap_rng",
 184         .bus            = &platform_bus_type,
 185         .probe          = omap_rng_probe,
 186         .remove         = __exit_p(omap_rng_remove),
 187         .suspend        = omap_rng_suspend,
 188         .resume         = omap_rng_resume
 189 };
 190
 191 static int __init omap_rng_init(void)
 192 {
 193         if (!cpu_is_omap16xx() && !cpu_is_omap24xx())
 194                 return -ENODEV;
 195
 196         return driver_register(&omap_rng_driver);
 197 }
 198
 199 static void __exit omap_rng_exit(void)
 200 {
 201         driver_unregister(&omap_rng_driver);
 202 }
 203
 204 module_init(omap_rng_init);
 205 module_exit(omap_rng_exit);
 206
 207 MODULE_AUTHOR("Deepak Saxena (and others)");
 208 MODULE_LICENSE("GPL");