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amd-rng.c

/*
 * RNG driver for AMD RNGs
 *
 * Copyright 2005 (c) MontaVista Software, Inc.
 *
 * with the majority of the code coming from:
 *
 * Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
 * (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
 *
 * derived from
 *
 * Hardware driver for the AMD 768 Random Number Generator (RNG)
 * (c) Copyright 2001 Red Hat Inc <alan@redhat.com>
 *
 * derived from
 *
 * Hardware driver for Intel i810 Random Number Generator (RNG)
 * Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
 * Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
 *
 * This file is licensed under  the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/hw_random.h>
#include <asm/io.h>


#define PFX KBUILD_MODNAME ": "


/*
 * Data for PCI driver interface
 *
 * This data only exists for exporting the supported
 * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
 * register a pci_driver, because someone else might one day
 * want to register another driver on the same PCI id.
 */
static const struct pci_device_id pci_tbl[] = {
      { 0x1022, 0x7443, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
      { 0x1022, 0x746b, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
      { 0, },     /* terminate list */
};
MODULE_DEVICE_TABLE(pci, pci_tbl);

static struct pci_dev *amd_pdev;


static int amd_rng_data_present(struct hwrng *rng)
{
      u32 pmbase = (u32)rng->priv;

            return !!(inl(pmbase + 0xF4) & 1);
}

static int amd_rng_data_read(struct hwrng *rng, u32 *data)
{
      u32 pmbase = (u32)rng->priv;

      *data = inl(pmbase + 0xF0);

      return 4;
}

static int amd_rng_init(struct hwrng *rng)
{
      u8 rnen;

      pci_read_config_byte(amd_pdev, 0x40, &rnen);
      rnen |= (1 << 7); /* RNG on */
      pci_write_config_byte(amd_pdev, 0x40, rnen);

      pci_read_config_byte(amd_pdev, 0x41, &rnen);
      rnen |= (1 << 7); /* PMIO enable */
      pci_write_config_byte(amd_pdev, 0x41, rnen);

      return 0;
}

static void amd_rng_cleanup(struct hwrng *rng)
{
      u8 rnen;

      pci_read_config_byte(amd_pdev, 0x40, &rnen);
      rnen &= ~(1 << 7);      /* RNG off */
      pci_write_config_byte(amd_pdev, 0x40, rnen);
}


static struct hwrng amd_rng = {
      .name       = "amd",
      .init       = amd_rng_init,
      .cleanup    = amd_rng_cleanup,
      .data_present     = amd_rng_data_present,
      .data_read  = amd_rng_data_read,
};


static int __init mod_init(void)
{
      int err = -ENODEV;
      struct pci_dev *pdev = NULL;
      const struct pci_device_id *ent;
      u32 pmbase;

      for_each_pci_dev(pdev) {
            ent = pci_match_id(pci_tbl, pdev);
            if (ent)
                  goto found;
      }
      /* Device not found. */
      goto out;

found:
      err = pci_read_config_dword(pdev, 0x58, &pmbase);
      if (err)
            goto out;
      err = -EIO;
      pmbase &= 0x0000FF00;
      if (pmbase == 0)
            goto out;
      amd_rng.priv = (unsigned long)pmbase;
      amd_pdev = pdev;

      printk(KERN_INFO "AMD768 RNG detected\n");
      err = hwrng_register(&amd_rng);
      if (err) {
            printk(KERN_ERR PFX "RNG registering failed (%d)\n",
                   err);
            goto out;
      }
out:
      return err;
}

static void __exit mod_exit(void)
{
      hwrng_unregister(&amd_rng);
}

module_init(mod_init);
module_exit(mod_exit);

MODULE_AUTHOR("The Linux Kernel team");
MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets");
MODULE_LICENSE("GPL");

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