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 <alan@redhat.com>
  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 <asm/io.h>
  32
  33
  34 #define PFX     KBUILD_MODNAME ": "
  35
  36
  37 /*
  38  * Data for PCI driver interface
  39  *
  40  * This data only exists for exporting the supported
  41  * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
  42  * register a pci_driver, because someone else might one day
  43  * want to register another driver on the same PCI id.
  44  */
  45 static const struct pci_device_id pci_tbl[] = {
  46         { 0x1022, 0x7443, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
  47         { 0x1022, 0x746b, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
  48         { 0, }, /* terminate list */
  49 };
  50 MODULE_DEVICE_TABLE(pci, pci_tbl);
  51
  52 static struct pci_dev *amd_pdev;
  53
  54
  55 static int amd_rng_data_present(struct hwrng *rng)
  56 {
  57         u32 pmbase = (u32)rng->priv;
  58
  59         return !!(inl(pmbase + 0xF4) & 1);
  60 }
  61
  62 static int amd_rng_data_read(struct hwrng *rng, u32 *data)
  63 {
  64         u32 pmbase = (u32)rng->priv;
  65
  66         *data = inl(pmbase + 0xF0);
  67
  68         return 4;
  69 }
  70
  71 static int amd_rng_init(struct hwrng *rng)
  72 {
  73         u8 rnen;
  74
  75         pci_read_config_byte(amd_pdev, 0x40, &rnen);
  76         rnen |= (1 << 7);       /* RNG on */
  77         pci_write_config_byte(amd_pdev, 0x40, rnen);
  78
  79         pci_read_config_byte(amd_pdev, 0x41, &rnen);
  80         rnen |= (1 << 7);       /* PMIO enable */
  81         pci_write_config_byte(amd_pdev, 0x41, rnen);
  82
  83         return 0;
  84 }
  85
  86 static void amd_rng_cleanup(struct hwrng *rng)
  87 {
  88         u8 rnen;
  89
  90         pci_read_config_byte(amd_pdev, 0x40, &rnen);
  91         rnen &= ~(1 << 7);      /* RNG off */
  92         pci_write_config_byte(amd_pdev, 0x40, rnen);
  93 }
  94
  95
  96 static struct hwrng amd_rng = {
  97         .name           = "amd",
  98         .init           = amd_rng_init,
  99         .cleanup        = amd_rng_cleanup,
 100         .data_present   = amd_rng_data_present,
 101         .data_read      = amd_rng_data_read,
 102 };
 103
 104
 105 static int __init mod_init(void)
 106 {
 107         int err = -ENODEV;
 108         struct pci_dev *pdev = NULL;
 109         const struct pci_device_id *ent;
 110         u32 pmbase;
 111
 112         for_each_pci_dev(pdev) {
 113                 ent = pci_match_id(pci_tbl, pdev);
 114                 if (ent)
 115                         goto found;
 116         }
 117         /* Device not found. */
 118         goto out;
 119
 120 found:
 121         err = pci_read_config_dword(pdev, 0x58, &pmbase);
 122         if (err)
 123                 goto out;
 124         err = -EIO;
 125         pmbase &= 0x0000FF00;
 126         if (pmbase == 0)
 127                 goto out;
 128         amd_rng.priv = (unsigned long)pmbase;
 129         amd_pdev = pdev;
 130
 131         printk(KERN_INFO "AMD768 RNG detected\n");
 132         err = hwrng_register(&amd_rng);
 133         if (err) {
 134                 printk(KERN_ERR PFX "RNG registering failed (%d)\n",
 135                        err);
 136                 goto out;
 137         }
 138 out:
 139         return err;
 140 }
 141
 142 static void __exit mod_exit(void)
 143 {
 144         hwrng_unregister(&amd_rng);
 145 }
 146
 147 module_init(mod_init);
 148 module_exit(mod_exit);
 149
 150 MODULE_AUTHOR("The Linux Kernel team");
 151 MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets");
 152 MODULE_LICENSE("GPL");