drivers/char/hw_random/geode-rng.c

   1 /*
   2  * RNG driver for AMD Geode 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 <linux/delay.h>
  32 #include <asm/io.h>
  33
  34
  35 #define PFX     KBUILD_MODNAME ": "
  36
  37 #define GEODE_RNG_DATA_REG   0x50
  38 #define GEODE_RNG_STATUS_REG 0x54
  39
  40 /*
  41  * Data for PCI driver interface
  42  *
  43  * This data only exists for exporting the supported
  44  * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
  45  * register a pci_driver, because someone else might one day
  46  * want to register another driver on the same PCI id.
  47  */
  48 static const struct pci_device_id pci_tbl[] = {
  49         { PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_LX_AES,
  50           PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
  51         { 0, }, /* terminate list */
  52 };
  53 MODULE_DEVICE_TABLE(pci, pci_tbl);
  54
  55
  56 static int geode_rng_data_read(struct hwrng *rng, u32 *data)
  57 {
  58         void __iomem *mem = (void __iomem *)rng->priv;
  59
  60         *data = readl(mem + GEODE_RNG_DATA_REG);
  61
  62         return 4;
  63 }
  64
  65 static int geode_rng_data_present(struct hwrng *rng, int wait)
  66 {
  67         void __iomem *mem = (void __iomem *)rng->priv;
  68         int data, i;
  69
  70         for (i = 0; i < 20; i++) {
  71                 data = !!(readl(mem + GEODE_RNG_STATUS_REG));
  72                 if (data || !wait)
  73                         break;
  74                 udelay(10);
  75         }
  76         return data;
  77 }
  78
  79
  80 static struct hwrng geode_rng = {
  81         .name           = "geode",
  82         .data_present   = geode_rng_data_present,
  83         .data_read      = geode_rng_data_read,
  84 };
  85
  86
  87 static int __init mod_init(void)
  88 {
  89         int err = -ENODEV;
  90         struct pci_dev *pdev = NULL;
  91         const struct pci_device_id *ent;
  92         void __iomem *mem;
  93         unsigned long rng_base;
  94
  95         for_each_pci_dev(pdev) {
  96                 ent = pci_match_id(pci_tbl, pdev);
  97                 if (ent)
  98                         goto found;
  99         }
 100         /* Device not found. */
 101         goto out;
 102
 103 found:
 104         rng_base = pci_resource_start(pdev, 0);
 105         if (rng_base == 0)
 106                 goto out;
 107         err = -ENOMEM;
 108         mem = ioremap(rng_base, 0x58);
 109         if (!mem)
 110                 goto out;
 111         geode_rng.priv = (unsigned long)mem;
 112
 113         printk(KERN_INFO "AMD Geode RNG detected\n");
 114         err = hwrng_register(&geode_rng);
 115         if (err) {
 116                 printk(KERN_ERR PFX "RNG registering failed (%d)\n",
 117                        err);
 118                 goto err_unmap;
 119         }
 120 out:
 121         return err;
 122
 123 err_unmap:
 124         iounmap(mem);
 125         goto out;
 126 }
 127
 128 static void __exit mod_exit(void)
 129 {
 130         void __iomem *mem = (void __iomem *)geode_rng.priv;
 131
 132         hwrng_unregister(&geode_rng);
 133         iounmap(mem);
 134 }
 135
 136 module_init(mod_init);
 137 module_exit(mod_exit);
 138
 139 MODULE_DESCRIPTION("H/W RNG driver for AMD Geode LX CPUs");
 140 MODULE_LICENSE("GPL");