drivers/char/hw_random/amd-rng.c

   1 /*
   2  * RNG driver for AMD RNGs
   3  *
   4  * Copyright 2005 (c) MontaVista Software, Inc.
   5  *
   6  * with the majority of the code coming from:
   7  *
   8  * Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
   9  * (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
  10  *
  11  * derived from
  12  *
  13  * Hardware driver for the AMD 768 Random Number Generator (RNG)
  14  * (c) Copyright 2001 Red Hat Inc
  15  *
  16  * derived from
  17  *
  18  * Hardware driver for Intel i810 Random Number Generator (RNG)
  19  * Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
  20  * Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
  21  *
  22  * This file is licensed under  the terms of the GNU General Public
  23  * License version 2. This program is licensed "as is" without any
  24  * warranty of any kind, whether express or implied.
  25  */
  26
  27 #include <linux/module.h>
  28 #include <linux/kernel.h>
  29 #include <linux/pci.h>
  30 #include <linux/hw_random.h>
  31 #include <linux/delay.h>
  32 #include <asm/io.h>
  33
  34
  35 #define PFX     KBUILD_MODNAME ": "
  36
  37
  38 /*
  39  * Data for PCI driver interface
  40  *
  41  * This data only exists for exporting the supported
  42  * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
  43  * register a pci_driver, because someone else might one day
  44  * want to register another driver on the same PCI id.
  45  */
  46 static const struct pci_device_id pci_tbl[] = {
  47         { PCI_VDEVICE(AMD, 0x7443), 0, },
  48         { PCI_VDEVICE(AMD, 0x746b), 0, },
  49         { 0, }, /* terminate list */
  50 };
  51 MODULE_DEVICE_TABLE(pci, pci_tbl);
  52
  53 static struct pci_dev *amd_pdev;
  54
  55
  56 static int amd_rng_data_present(struct hwrng *rng, int wait)
  57 {
  58         u32 pmbase = (u32)rng->priv;
  59         int data, i;
  60
  61         for (i = 0; i < 20; i++) {
  62                 data = !!(inl(pmbase + 0xF4) & 1);
  63                 if (data || !wait)
  64                         break;
  65                 udelay(10);
  66         }
  67         return data;
  68 }
  69
  70 static int amd_rng_data_read(struct hwrng *rng, u32 *data)
  71 {
  72         u32 pmbase = (u32)rng->priv;
  73
  74         *data = inl(pmbase + 0xF0);
  75
  76         return 4;
  77 }
  78
  79 static int amd_rng_init(struct hwrng *rng)
  80 {
  81         u8 rnen;
  82
  83         pci_read_config_byte(amd_pdev, 0x40, &rnen);
  84         rnen |= (1 << 7);       /* RNG on */
  85         pci_write_config_byte(amd_pdev, 0x40, rnen);
  86
  87         pci_read_config_byte(amd_pdev, 0x41, &rnen);
  88         rnen |= (1 << 7);       /* PMIO enable */
  89         pci_write_config_byte(amd_pdev, 0x41, rnen);
  90
  91         return 0;
  92 }
  93
  94 static void amd_rng_cleanup(struct hwrng *rng)
  95 {
  96         u8 rnen;
  97
  98         pci_read_config_byte(amd_pdev, 0x40, &rnen);
  99         rnen &= ~(1 << 7);      /* RNG off */
 100         pci_write_config_byte(amd_pdev, 0x40, rnen);
 101 }
 102
 103
 104 static struct hwrng amd_rng = {
 105         .name           = "amd",
 106         .init           = amd_rng_init,
 107         .cleanup        = amd_rng_cleanup,
 108         .data_present   = amd_rng_data_present,
 109         .data_read      = amd_rng_data_read,
 110 };
 111
 112
 113 static int __init mod_init(void)
 114 {
 115         int err = -ENODEV;
 116         struct pci_dev *pdev = NULL;
 117         const struct pci_device_id *ent;
 118         u32 pmbase;
 119
 120         for_each_pci_dev(pdev) {
 121                 ent = pci_match_id(pci_tbl, pdev);
 122                 if (ent)
 123                         goto found;
 124         }
 125         /* Device not found. */
 126         goto out;
 127
 128 found:
 129         err = pci_read_config_dword(pdev, 0x58, &pmbase);
 130         if (err)
 131                 goto out;
 132         err = -EIO;
 133         pmbase &= 0x0000FF00;
 134         if (pmbase == 0)
 135                 goto out;
 136         if (!request_region(pmbase + 0xF0, 8, "AMD HWRNG")) {
 137                 dev_err(&pdev->dev, "AMD HWRNG region 0x%x already in use!\n",
 138                         pmbase + 0xF0);
 139                 err = -EBUSY;
 140                 goto out;
 141         }
 142         amd_rng.priv = (unsigned long)pmbase;
 143         amd_pdev = pdev;
 144
 145         pr_info("AMD768 RNG detected\n");
 146         err = hwrng_register(&amd_rng);
 147         if (err) {
 148                 pr_err(PFX "RNG registering failed (%d)\n",
 149                        err);
 150                 release_region(pmbase + 0xF0, 8);
 151                 goto out;
 152         }
 153 out:
 154         return err;
 155 }
 156
 157 static void __exit mod_exit(void)
 158 {
 159         u32 pmbase = (unsigned long)amd_rng.priv;
 160         release_region(pmbase + 0xF0, 8);
 161         hwrng_unregister(&amd_rng);
 162 }
 163
 164 module_init(mod_init);
 165 module_exit(mod_exit);
 166
 167 MODULE_AUTHOR("The Linux Kernel team");
 168 MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets");
 169 MODULE_LICENSE("GPL");