diff options
Diffstat (limited to 'drivers/char/hw_random/intel-rng.c')
| -rw-r--r-- | drivers/char/hw_random/intel-rng.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/drivers/char/hw_random/intel-rng.c b/drivers/char/hw_random/intel-rng.c new file mode 100644 index 00000000000..6594bd5645f --- /dev/null +++ b/drivers/char/hw_random/intel-rng.c @@ -0,0 +1,189 @@ +/* + * RNG driver for Intel 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 ": " + +/* + * RNG registers + */ +#define INTEL_RNG_HW_STATUS 0 +#define INTEL_RNG_PRESENT 0x40 +#define INTEL_RNG_ENABLED 0x01 +#define INTEL_RNG_STATUS 1 +#define INTEL_RNG_DATA_PRESENT 0x01 +#define INTEL_RNG_DATA 2 + +/* + * Magic address at which Intel PCI bridges locate the RNG + */ +#define INTEL_RNG_ADDR 0xFFBC015F +#define INTEL_RNG_ADDR_LEN 3 + +/* + * 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[] = { + { 0x8086, 0x2418, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, + { 0x8086, 0x2428, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, + { 0x8086, 0x2430, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, + { 0x8086, 0x2448, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, + { 0x8086, 0x244e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, + { 0x8086, 0x245e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, + { 0, }, /* terminate list */ +}; +MODULE_DEVICE_TABLE(pci, pci_tbl); + + +static inline u8 hwstatus_get(void __iomem *mem) +{ + return readb(mem + INTEL_RNG_HW_STATUS); +} + +static inline u8 hwstatus_set(void __iomem *mem, + u8 hw_status) +{ + writeb(hw_status, mem + INTEL_RNG_HW_STATUS); + return hwstatus_get(mem); +} + +static int intel_rng_data_present(struct hwrng *rng) +{ + void __iomem *mem = (void __iomem *)rng->priv; + + return !!(readb(mem + INTEL_RNG_STATUS) & INTEL_RNG_DATA_PRESENT); +} + +static int intel_rng_data_read(struct hwrng *rng, u32 *data) +{ + void __iomem *mem = (void __iomem *)rng->priv; + + *data = readb(mem + INTEL_RNG_DATA); + + return 1; +} + +static int intel_rng_init(struct hwrng *rng) +{ + void __iomem *mem = (void __iomem *)rng->priv; + u8 hw_status; + int err = -EIO; + + hw_status = hwstatus_get(mem); + /* turn RNG h/w on, if it's off */ + if ((hw_status & INTEL_RNG_ENABLED) == 0) + hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED); + if ((hw_status & INTEL_RNG_ENABLED) == 0) { + printk(KERN_ERR PFX "cannot enable RNG, aborting\n"); + goto out; + } + err = 0; +out: + return err; +} + +static void intel_rng_cleanup(struct hwrng *rng) +{ + void __iomem *mem = (void __iomem *)rng->priv; + u8 hw_status; + + hw_status = hwstatus_get(mem); + if (hw_status & INTEL_RNG_ENABLED) + hwstatus_set(mem, hw_status & ~INTEL_RNG_ENABLED); + else + printk(KERN_WARNING PFX "unusual: RNG already disabled\n"); +} + + +static struct hwrng intel_rng = { + .name = "intel", + .init = intel_rng_init, + .cleanup = intel_rng_cleanup, + .data_present = intel_rng_data_present, + .data_read = intel_rng_data_read, +}; + + +static int __init mod_init(void) +{ + int err = -ENODEV; + void __iomem *mem; + u8 hw_status; + + if (!pci_dev_present(pci_tbl)) + goto out; /* Device not found. */ + + err = -ENOMEM; + mem = ioremap(INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN); + if (!mem) + goto out; + intel_rng.priv = (unsigned long)mem; + + /* Check for Intel 82802 */ + err = -ENODEV; + hw_status = hwstatus_get(mem); + if ((hw_status & INTEL_RNG_PRESENT) == 0) + goto err_unmap; + + printk(KERN_INFO "Intel 82802 RNG detected\n"); + err = hwrng_register(&intel_rng); + if (err) { + printk(KERN_ERR PFX "RNG registering failed (%d)\n", + err); + goto out; + } +out: + return err; + +err_unmap: + iounmap(mem); + goto out; +} + +static void __exit mod_exit(void) +{ + void __iomem *mem = (void __iomem *)intel_rng.priv; + + hwrng_unregister(&intel_rng); + iounmap(mem); +} + +subsys_initcall(mod_init); +module_exit(mod_exit); + +MODULE_DESCRIPTION("H/W RNG driver for Intel chipsets"); +MODULE_LICENSE("GPL"); |