target/linux/ubicom32/files/drivers/char/hw_random/ubicom32-rng.c

   1 /*
   2  * drivers/net/ubi32-eth.c
   3  *   Ubicom32 hardware random number generator driver.
   4  *
   5  * (C) Copyright 2009, Ubicom, Inc.
   6  *
   7  * This file is part of the Ubicom32 Linux Kernel Port.
   8  *
   9  * The Ubicom32 Linux Kernel Port is free software: you can redistribute
  10  * it and/or modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation, either version 2 of the
  12  * License, or (at your option) any later version.
  13  *
  14  * The Ubicom32 Linux Kernel Port is distributed in the hope that it
  15  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  16  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  17  * the GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with the Ubicom32 Linux Kernel Port.  If not,
  21  * see <http://www.gnu.org/licenses/>.
  22  *
  23  * Ubicom32 implementation derived from (with many thanks):
  24  *   arch/m68knommu
  25  *   arch/blackfin
  26  *   arch/parisc
  27  */
  28
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/hw_random.h>
  32 #include <linux/delay.h>
  33 #include <asm/io.h>
  34 #include <asm/ip5000.h>
  35
  36 #define MODULE_NAME "ubicom32_rng"
  37
  38 static int ubicom32_rng_data_present(struct hwrng *rng, int wait)
  39 {
  40         int data, i;
  41
  42         for (i = 0; i < 20; i++) {
  43                 data = *(int *)(TIMER_BASE + TIMER_TRN);
  44                 if (data || !wait)
  45                         break;
  46                 udelay(10);
  47         }
  48         return data;
  49 }
  50
  51 static int ubicom32_rng_data_read(struct hwrng *rng, u32 *data)
  52 {
  53         *data = *(int *)(TIMER_BASE + TIMER_TRN);
  54         return 4;
  55 }
  56
  57 static int ubicom32_rng_init(struct hwrng *rng)
  58 {
  59         printk(KERN_INFO "ubicom32 rng init\n");
  60         *(int *)(TIMER_BASE + TIMER_TRN_CFG) = TIMER_TRN_CFG_ENABLE_OSC;
  61         return 0;
  62 }
  63
  64 static void ubicom32_rng_cleanup(struct hwrng *rng)
  65 {
  66         printk(KERN_INFO "ubicom32 rng cleanup\n");
  67         *(int *)(TIMER_BASE + TIMER_TRN_CFG) = 0;
  68 }
  69
  70 static struct hwrng ubicom32_rng = {
  71         .name           = MODULE_NAME,
  72         .init           = ubicom32_rng_init,
  73         .cleanup        = ubicom32_rng_cleanup,
  74         .data_present   = ubicom32_rng_data_present,
  75         .data_read      = ubicom32_rng_data_read,
  76         .priv           = 0,
  77 };
  78
  79 static int __init mod_init(void)
  80 {
  81         int err;
  82
  83         printk(KERN_INFO "ubicom32 rng started\n");
  84         err = hwrng_register(&ubicom32_rng);
  85         if (err) {
  86                 printk(KERN_ERR "ubicom32 rng register failed (%d)\n",
  87                         err);
  88         }
  89
  90         return err;
  91 }
  92
  93 static void __exit mod_exit(void)
  94 {
  95         printk(KERN_INFO "ubicom32 rng stopped\n");
  96         hwrng_unregister(&ubicom32_rng);
  97 }
  98
  99 module_init(mod_init);
 100 module_exit(mod_exit);
 101
 102 MODULE_LICENSE("GPL");
 103 MODULE_AUTHOR("Ubicom, Inc.");
 104 MODULE_DESCRIPTION("H/W rng driver for ubicom32 processor");
 105 MODULE_VERSION("1:1.0.a");