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