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
  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/delay.h>
  28 #include <linux/hw_random.h>
  29 #include <linux/io.h>
  30 #include <linux/kernel.h>
  31 #include <linux/module.h>
  32 #include <linux/pci.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_VDEVICE(AMD, PCI_DEVICE_ID_AMD_LX_AES), 0, },
  50         { 0, }, /* terminate list */
  51 };
  52 MODULE_DEVICE_TABLE(pci, pci_tbl);
  53
  54 struct amd_geode_priv {
  55         struct pci_dev *pcidev;
  56         void __iomem *membase;
  57 };
  58
  59 static int geode_rng_data_read(struct hwrng *rng, u32 *data)
  60 {
  61         struct amd_geode_priv *priv = (struct amd_geode_priv *)rng->priv;
  62         void __iomem *mem = priv->membase;
  63
  64         *data = readl(mem + GEODE_RNG_DATA_REG);
  65
  66         return 4;
  67 }
  68
  69 static int geode_rng_data_present(struct hwrng *rng, int wait)
  70 {
  71         struct amd_geode_priv *priv = (struct amd_geode_priv *)rng->priv;
  72         void __iomem *mem = priv->membase;
  73         int data, i;
  74
  75         for (i = 0; i < 20; i++) {
  76                 data = !!(readl(mem + GEODE_RNG_STATUS_REG));
  77                 if (data || !wait)
  78                         break;
  79                 udelay(10);
  80         }
  81         return data;
  82 }
  83
  84
  85 static struct hwrng geode_rng = {
  86         .name           = "geode",
  87         .data_present   = geode_rng_data_present,
  88         .data_read      = geode_rng_data_read,
  89 };
  90
  91
  92 static int __init geode_rng_init(void)
  93 {
  94         int err = -ENODEV;
  95         struct pci_dev *pdev = NULL;
  96         const struct pci_device_id *ent;
  97         void __iomem *mem;
  98         unsigned long rng_base;
  99         struct amd_geode_priv *priv;
 100
 101         for_each_pci_dev(pdev) {
 102                 ent = pci_match_id(pci_tbl, pdev);
 103                 if (ent)
 104                         goto found;
 105         }
 106         /* Device not found. */
 107         return err;
 108
 109 found:
 110         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 111         if (!priv) {
 112                 err = -ENOMEM;
 113                 goto put_dev;
 114         }
 115
 116         rng_base = pci_resource_start(pdev, 0);
 117         if (rng_base == 0)
 118                 goto free_priv;
 119         err = -ENOMEM;
 120         mem = ioremap(rng_base, 0x58);
 121         if (!mem)
 122                 goto free_priv;
 123
 124         geode_rng.priv = (unsigned long)priv;
 125         priv->membase = mem;
 126         priv->pcidev = pdev;
 127
 128         pr_info("AMD Geode RNG detected\n");
 129         err = hwrng_register(&geode_rng);
 130         if (err) {
 131                 pr_err(PFX "RNG registering failed (%d)\n",
 132                        err);
 133                 goto err_unmap;
 134         }
 135         return err;
 136
 137 err_unmap:
 138         iounmap(mem);
 139 free_priv:
 140         kfree(priv);
 141 put_dev:
 142         pci_dev_put(pdev);
 143         return err;
 144 }
 145
 146 static void __exit geode_rng_exit(void)
 147 {
 148         struct amd_geode_priv *priv;
 149
 150         priv = (struct amd_geode_priv *)geode_rng.priv;
 151         hwrng_unregister(&geode_rng);
 152         iounmap(priv->membase);
 153         pci_dev_put(priv->pcidev);
 154         kfree(priv);
 155 }
 156
 157 module_init(geode_rng_init);
 158 module_exit(geode_rng_exit);
 159
 160 MODULE_DESCRIPTION("H/W RNG driver for AMD Geode LX CPUs");
 161 MODULE_LICENSE("GPL");