190 lines
4.4 KiB
C
190 lines
4.4 KiB
C
/*
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* RNG driver for Intel RNGs
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*
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* Copyright 2005 (c) MontaVista Software, Inc.
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*
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* with the majority of the code coming from:
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*
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* Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
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* (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
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*
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* derived from
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*
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* Hardware driver for the AMD 768 Random Number Generator (RNG)
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* (c) Copyright 2001 Red Hat Inc <alan@redhat.com>
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*
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* derived from
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*
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* Hardware driver for Intel i810 Random Number Generator (RNG)
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* Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
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* Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/pci.h>
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#include <linux/hw_random.h>
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#include <asm/io.h>
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#define PFX KBUILD_MODNAME ": "
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/*
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* RNG registers
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*/
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#define INTEL_RNG_HW_STATUS 0
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#define INTEL_RNG_PRESENT 0x40
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#define INTEL_RNG_ENABLED 0x01
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#define INTEL_RNG_STATUS 1
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#define INTEL_RNG_DATA_PRESENT 0x01
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#define INTEL_RNG_DATA 2
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/*
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* Magic address at which Intel PCI bridges locate the RNG
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*/
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#define INTEL_RNG_ADDR 0xFFBC015F
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#define INTEL_RNG_ADDR_LEN 3
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/*
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* Data for PCI driver interface
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*
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* This data only exists for exporting the supported
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* PCI ids via MODULE_DEVICE_TABLE. We do not actually
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* register a pci_driver, because someone else might one day
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* want to register another driver on the same PCI id.
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*/
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static const struct pci_device_id pci_tbl[] = {
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{ 0x8086, 0x2418, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
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{ 0x8086, 0x2428, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
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{ 0x8086, 0x2430, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
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{ 0x8086, 0x2448, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
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{ 0x8086, 0x244e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
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{ 0x8086, 0x245e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
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{ 0, }, /* terminate list */
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};
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MODULE_DEVICE_TABLE(pci, pci_tbl);
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static inline u8 hwstatus_get(void __iomem *mem)
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{
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return readb(mem + INTEL_RNG_HW_STATUS);
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}
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static inline u8 hwstatus_set(void __iomem *mem,
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u8 hw_status)
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{
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writeb(hw_status, mem + INTEL_RNG_HW_STATUS);
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return hwstatus_get(mem);
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}
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static int intel_rng_data_present(struct hwrng *rng)
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{
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void __iomem *mem = (void __iomem *)rng->priv;
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return !!(readb(mem + INTEL_RNG_STATUS) & INTEL_RNG_DATA_PRESENT);
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}
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static int intel_rng_data_read(struct hwrng *rng, u32 *data)
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{
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void __iomem *mem = (void __iomem *)rng->priv;
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*data = readb(mem + INTEL_RNG_DATA);
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return 1;
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}
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static int intel_rng_init(struct hwrng *rng)
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{
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void __iomem *mem = (void __iomem *)rng->priv;
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u8 hw_status;
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int err = -EIO;
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hw_status = hwstatus_get(mem);
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/* turn RNG h/w on, if it's off */
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if ((hw_status & INTEL_RNG_ENABLED) == 0)
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hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED);
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if ((hw_status & INTEL_RNG_ENABLED) == 0) {
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printk(KERN_ERR PFX "cannot enable RNG, aborting\n");
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goto out;
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}
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err = 0;
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out:
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return err;
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}
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static void intel_rng_cleanup(struct hwrng *rng)
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{
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void __iomem *mem = (void __iomem *)rng->priv;
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u8 hw_status;
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hw_status = hwstatus_get(mem);
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if (hw_status & INTEL_RNG_ENABLED)
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hwstatus_set(mem, hw_status & ~INTEL_RNG_ENABLED);
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else
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printk(KERN_WARNING PFX "unusual: RNG already disabled\n");
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}
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static struct hwrng intel_rng = {
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.name = "intel",
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.init = intel_rng_init,
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.cleanup = intel_rng_cleanup,
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.data_present = intel_rng_data_present,
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.data_read = intel_rng_data_read,
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};
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static int __init mod_init(void)
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{
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int err = -ENODEV;
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void __iomem *mem;
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u8 hw_status;
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if (!pci_dev_present(pci_tbl))
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goto out; /* Device not found. */
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err = -ENOMEM;
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mem = ioremap(INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
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if (!mem)
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goto out;
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intel_rng.priv = (unsigned long)mem;
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/* Check for Intel 82802 */
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err = -ENODEV;
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hw_status = hwstatus_get(mem);
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if ((hw_status & INTEL_RNG_PRESENT) == 0)
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goto err_unmap;
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printk(KERN_INFO "Intel 82802 RNG detected\n");
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err = hwrng_register(&intel_rng);
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if (err) {
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printk(KERN_ERR PFX "RNG registering failed (%d)\n",
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err);
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goto out;
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}
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out:
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return err;
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err_unmap:
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iounmap(mem);
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goto out;
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}
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static void __exit mod_exit(void)
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{
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void __iomem *mem = (void __iomem *)intel_rng.priv;
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hwrng_unregister(&intel_rng);
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iounmap(mem);
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}
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subsys_initcall(mod_init);
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module_exit(mod_exit);
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MODULE_DESCRIPTION("H/W RNG driver for Intel chipsets");
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MODULE_LICENSE("GPL");
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