drivers/char/hw_random/ixp4xx-rng.c

   1 /*
   2  * drivers/char/hw_random/ixp4xx-rng.c
   3  *
   4  * RNG driver for Intel IXP4xx family of NPUs
   5  *
   6  * Author: Deepak Saxena <dsaxena@plexity.net>
   7  *
   8  * Copyright 2005 (c) MontaVista Software, Inc.
   9  *
  10  * Fixes by Michael Buesch
  11  *
  12  * This file is licensed under  the terms of the GNU General Public
  13  * License version 2. This program is licensed "as is" without any
  14  * warranty of any kind, whether express or implied.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/types.h>
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/init.h>
  22 #include <linux/bitops.h>
  23 #include <linux/hw_random.h>
  24
  25 #include <asm/io.h>
  26 #include <mach/hardware.h>
  27
  28
  29 static int ixp4xx_rng_data_read(struct hwrng *rng, u32 *buffer)
  30 {
  31         void __iomem * rng_base = (void __iomem *)rng->priv;
  32
  33         *buffer = __raw_readl(rng_base);
  34
  35         return 4;
  36 }
  37
  38 static struct hwrng ixp4xx_rng_ops = {
  39         .name           = "ixp4xx",
  40         .data_read      = ixp4xx_rng_data_read,
  41 };
  42
  43 static int __init ixp4xx_rng_init(void)
  44 {
  45         void __iomem * rng_base;
  46         int err;
  47
  48         if (!cpu_is_ixp46x()) /* includes IXP455 */
  49                 return -ENOSYS;
  50
  51         rng_base = ioremap(0x70002100, 4);
  52         if (!rng_base)
  53                 return -ENOMEM;
  54         ixp4xx_rng_ops.priv = (unsigned long)rng_base;
  55         err = hwrng_register(&ixp4xx_rng_ops);
  56         if (err)
  57                 iounmap(rng_base);
  58
  59         return err;
  60 }
  61
  62 static void __exit ixp4xx_rng_exit(void)
  63 {
  64         void __iomem * rng_base = (void __iomem *)ixp4xx_rng_ops.priv;
  65
  66         hwrng_unregister(&ixp4xx_rng_ops);
  67         iounmap(rng_base);
  68 }
  69
  70 module_init(ixp4xx_rng_init);
  71 module_exit(ixp4xx_rng_exit);
  72
  73 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
  74 MODULE_DESCRIPTION("H/W Pseudo-Random Number Generator (RNG) driver for IXP45x/46x");
  75 MODULE_LICENSE("GPL");