drivers/char/hw_random/pasemi-rng.c

   1 /*
   2  * Copyright (C) 2006-2007 PA Semi, Inc
   3  *
   4  * Maintained by: Olof Johansson <olof@lixom.net>
   5  *
   6  * Driver for the PWRficient onchip rng
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/kernel.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/hw_random.h>
  26 #include <asm/of_platform.h>
  27 #include <asm/io.h>
  28
  29 #define SDCRNG_CTL_REG                  0x00
  30 #define   SDCRNG_CTL_FVLD_M             0x0000f000
  31 #define   SDCRNG_CTL_FVLD_S             12
  32 #define   SDCRNG_CTL_KSZ                0x00000800
  33 #define   SDCRNG_CTL_RSRC_CRG           0x00000010
  34 #define   SDCRNG_CTL_RSRC_RRG           0x00000000
  35 #define   SDCRNG_CTL_CE                 0x00000004
  36 #define   SDCRNG_CTL_RE                 0x00000002
  37 #define   SDCRNG_CTL_DR                 0x00000001
  38 #define   SDCRNG_CTL_SELECT_RRG_RNG     (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
  39 #define   SDCRNG_CTL_SELECT_CRG_RNG     (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
  40 #define SDCRNG_VAL_REG                  0x20
  41
  42 #define MODULE_NAME "pasemi_rng"
  43
  44 static int pasemi_rng_data_present(struct hwrng *rng)
  45 {
  46         void __iomem *rng_regs = (void __iomem *)rng->priv;
  47
  48         return (in_le32(rng_regs + SDCRNG_CTL_REG)
  49                 & SDCRNG_CTL_FVLD_M) ? 1 : 0;
  50 }
  51
  52 static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
  53 {
  54         void __iomem *rng_regs = (void __iomem *)rng->priv;
  55         *data = in_le32(rng_regs + SDCRNG_VAL_REG);
  56         return 4;
  57 }
  58
  59 static int pasemi_rng_init(struct hwrng *rng)
  60 {
  61         void __iomem *rng_regs = (void __iomem *)rng->priv;
  62         u32 ctl;
  63
  64         ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
  65         out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
  66         out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
  67
  68         return 0;
  69 }
  70
  71 static void pasemi_rng_cleanup(struct hwrng *rng)
  72 {
  73         void __iomem *rng_regs = (void __iomem *)rng->priv;
  74         u32 ctl;
  75
  76         ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
  77         out_le32(rng_regs + SDCRNG_CTL_REG,
  78                  in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
  79 }
  80
  81 static struct hwrng pasemi_rng = {
  82         .name           = MODULE_NAME,
  83         .init           = pasemi_rng_init,
  84         .cleanup        = pasemi_rng_cleanup,
  85         .data_present   = pasemi_rng_data_present,
  86         .data_read      = pasemi_rng_data_read,
  87 };
  88
  89 static int __devinit rng_probe(struct of_device *ofdev,
  90                                const struct of_device_id *match)
  91 {
  92         void __iomem *rng_regs;
  93         struct device_node *rng_np = ofdev->node;
  94         struct resource res;
  95         int err = 0;
  96
  97         err = of_address_to_resource(rng_np, 0, &res);
  98         if (err)
  99                 return -ENODEV;
 100
 101         rng_regs = ioremap(res.start, 0x100);
 102
 103         if (!rng_regs)
 104                 return -ENOMEM;
 105
 106         pasemi_rng.priv = (unsigned long)rng_regs;
 107
 108         printk(KERN_INFO "Registering PA Semi RNG\n");
 109
 110         err = hwrng_register(&pasemi_rng);
 111
 112         if (err)
 113                 iounmap(rng_regs);
 114
 115         return err;
 116 }
 117
 118 static int __devexit rng_remove(struct of_device *dev)
 119 {
 120         void __iomem *rng_regs = (void __iomem *)pasemi_rng.priv;
 121
 122         hwrng_unregister(&pasemi_rng);
 123         iounmap(rng_regs);
 124
 125         return 0;
 126 }
 127
 128 static struct of_device_id rng_match[] = {
 129         {
 130                 .compatible      = "1682m-rng",
 131         },
 132         {},
 133 };
 134
 135 static struct of_platform_driver rng_driver = {
 136         .name           = "pasemi-rng",
 137         .match_table    = rng_match,
 138         .probe          = rng_probe,
 139         .remove         = rng_remove,
 140 };
 141
 142 static int __init rng_init(void)
 143 {
 144         return of_register_platform_driver(&rng_driver);
 145 }
 146 module_init(rng_init);
 147
 148 static void __exit rng_exit(void)
 149 {
 150         of_unregister_platform_driver(&rng_driver);
 151 }
 152 module_exit(rng_exit);
 153
 154 MODULE_LICENSE("GPL");
 155 MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
 156 MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");