drivers/char/hw_random/intel-rng.c

   1 /*
   2  * RNG driver for Intel 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 /*
  37  * RNG registers
  38  */
  39 #define INTEL_RNG_HW_STATUS                     0
  40 #define         INTEL_RNG_PRESENT               0x40
  41 #define         INTEL_RNG_ENABLED               0x01
  42 #define INTEL_RNG_STATUS                        1
  43 #define         INTEL_RNG_DATA_PRESENT          0x01
  44 #define INTEL_RNG_DATA                          2
  45
  46 /*
  47  * Magic address at which Intel PCI bridges locate the RNG
  48  */
  49 #define INTEL_RNG_ADDR                          0xFFBC015F
  50 #define INTEL_RNG_ADDR_LEN                      3
  51
  52 /*
  53  * LPC bridge PCI config space registers
  54  */
  55 #define FWH_DEC_EN1_REG_OLD                     0xe3
  56 #define FWH_DEC_EN1_REG_NEW                     0xd9 /* high byte of 16-bit register */
  57 #define FWH_F8_EN_MASK                          0x80
  58
  59 #define BIOS_CNTL_REG_OLD                       0x4e
  60 #define BIOS_CNTL_REG_NEW                       0xdc
  61 #define BIOS_CNTL_WRITE_ENABLE_MASK             0x01
  62 #define BIOS_CNTL_LOCK_ENABLE_MASK              0x02
  63
  64 /*
  65  * Magic address at which Intel Firmware Hubs get accessed
  66  */
  67 #define INTEL_FWH_ADDR                          0xffff0000
  68 #define INTEL_FWH_ADDR_LEN                      2
  69
  70 /*
  71  * Intel Firmware Hub command codes (write to any address inside the device)
  72  */
  73 #define INTEL_FWH_RESET_CMD                     0xff /* aka READ_ARRAY */
  74 #define INTEL_FWH_READ_ID_CMD                   0x90
  75
  76 /*
  77  * Intel Firmware Hub Read ID command result addresses
  78  */
  79 #define INTEL_FWH_MANUFACTURER_CODE_ADDRESS     0x000000
  80 #define INTEL_FWH_DEVICE_CODE_ADDRESS           0x000001
  81
  82 /*
  83  * Intel Firmware Hub Read ID command result values
  84  */
  85 #define INTEL_FWH_MANUFACTURER_CODE             0x89
  86 #define INTEL_FWH_DEVICE_CODE_8M                0xac
  87 #define INTEL_FWH_DEVICE_CODE_4M                0xad
  88
  89 /*
  90  * Data for PCI driver interface
  91  *
  92  * This data only exists for exporting the supported
  93  * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
  94  * register a pci_driver, because someone else might one day
  95  * want to register another driver on the same PCI id.
  96  */
  97 static const struct pci_device_id pci_tbl[] = {
  98 /* AA
  99         { PCI_DEVICE(0x8086, 0x2418) }, */
 100         { PCI_DEVICE(0x8086, 0x2410) }, /* AA */
 101 /* AB
 102         { PCI_DEVICE(0x8086, 0x2428) }, */
 103         { PCI_DEVICE(0x8086, 0x2420) }, /* AB */
 104 /* ??
 105         { PCI_DEVICE(0x8086, 0x2430) }, */
 106 /* BAM, CAM, DBM, FBM, GxM
 107         { PCI_DEVICE(0x8086, 0x2448) }, */
 108         { PCI_DEVICE(0x8086, 0x244c) }, /* BAM */
 109         { PCI_DEVICE(0x8086, 0x248c) }, /* CAM */
 110         { PCI_DEVICE(0x8086, 0x24cc) }, /* DBM */
 111         { PCI_DEVICE(0x8086, 0x2641) }, /* FBM */
 112         { PCI_DEVICE(0x8086, 0x27b9) }, /* GxM */
 113         { PCI_DEVICE(0x8086, 0x27bd) }, /* GxM DH */
 114 /* BA, CA, DB, Ex, 6300, Fx, 631x/632x, Gx
 115         { PCI_DEVICE(0x8086, 0x244e) }, */
 116         { PCI_DEVICE(0x8086, 0x2440) }, /* BA */
 117         { PCI_DEVICE(0x8086, 0x2480) }, /* CA */
 118         { PCI_DEVICE(0x8086, 0x24c0) }, /* DB */
 119         { PCI_DEVICE(0x8086, 0x24d0) }, /* Ex */
 120         { PCI_DEVICE(0x8086, 0x25a1) }, /* 6300 */
 121         { PCI_DEVICE(0x8086, 0x2640) }, /* Fx */
 122         { PCI_DEVICE(0x8086, 0x2670) }, /* 631x/632x */
 123         { PCI_DEVICE(0x8086, 0x2671) }, /* 631x/632x */
 124         { PCI_DEVICE(0x8086, 0x2672) }, /* 631x/632x */
 125         { PCI_DEVICE(0x8086, 0x2673) }, /* 631x/632x */
 126         { PCI_DEVICE(0x8086, 0x2674) }, /* 631x/632x */
 127         { PCI_DEVICE(0x8086, 0x2675) }, /* 631x/632x */
 128         { PCI_DEVICE(0x8086, 0x2676) }, /* 631x/632x */
 129         { PCI_DEVICE(0x8086, 0x2677) }, /* 631x/632x */
 130         { PCI_DEVICE(0x8086, 0x2678) }, /* 631x/632x */
 131         { PCI_DEVICE(0x8086, 0x2679) }, /* 631x/632x */
 132         { PCI_DEVICE(0x8086, 0x267a) }, /* 631x/632x */
 133         { PCI_DEVICE(0x8086, 0x267b) }, /* 631x/632x */
 134         { PCI_DEVICE(0x8086, 0x267c) }, /* 631x/632x */
 135         { PCI_DEVICE(0x8086, 0x267d) }, /* 631x/632x */
 136         { PCI_DEVICE(0x8086, 0x267e) }, /* 631x/632x */
 137         { PCI_DEVICE(0x8086, 0x267f) }, /* 631x/632x */
 138         { PCI_DEVICE(0x8086, 0x27b8) }, /* Gx */
 139 /* E
 140         { PCI_DEVICE(0x8086, 0x245e) }, */
 141         { PCI_DEVICE(0x8086, 0x2450) }, /* E  */
 142         { 0, }, /* terminate list */
 143 };
 144 MODULE_DEVICE_TABLE(pci, pci_tbl);
 145
 146 static __initdata int no_fwh_detect;
 147 module_param(no_fwh_detect, int, 0);
 148 MODULE_PARM_DESC(no_fwh_detect, "Skip FWH detection:\n"
 149                                 " positive value - skip if FWH space locked read-only\n"
 150                                 " negative value - skip always");
 151
 152 static inline u8 hwstatus_get(void __iomem *mem)
 153 {
 154         return readb(mem + INTEL_RNG_HW_STATUS);
 155 }
 156
 157 static inline u8 hwstatus_set(void __iomem *mem,
 158                               u8 hw_status)
 159 {
 160         writeb(hw_status, mem + INTEL_RNG_HW_STATUS);
 161         return hwstatus_get(mem);
 162 }
 163
 164 static int intel_rng_data_present(struct hwrng *rng)
 165 {
 166         void __iomem *mem = (void __iomem *)rng->priv;
 167
 168         return !!(readb(mem + INTEL_RNG_STATUS) & INTEL_RNG_DATA_PRESENT);
 169 }
 170
 171 static int intel_rng_data_read(struct hwrng *rng, u32 *data)
 172 {
 173         void __iomem *mem = (void __iomem *)rng->priv;
 174
 175         *data = readb(mem + INTEL_RNG_DATA);
 176
 177         return 1;
 178 }
 179
 180 static int intel_rng_init(struct hwrng *rng)
 181 {
 182         void __iomem *mem = (void __iomem *)rng->priv;
 183         u8 hw_status;
 184         int err = -EIO;
 185
 186         hw_status = hwstatus_get(mem);
 187         /* turn RNG h/w on, if it's off */
 188         if ((hw_status & INTEL_RNG_ENABLED) == 0)
 189                 hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED);
 190         if ((hw_status & INTEL_RNG_ENABLED) == 0) {
 191                 printk(KERN_ERR PFX "cannot enable RNG, aborting\n");
 192                 goto out;
 193         }
 194         err = 0;
 195 out:
 196         return err;
 197 }
 198
 199 static void intel_rng_cleanup(struct hwrng *rng)
 200 {
 201         void __iomem *mem = (void __iomem *)rng->priv;
 202         u8 hw_status;
 203
 204         hw_status = hwstatus_get(mem);
 205         if (hw_status & INTEL_RNG_ENABLED)
 206                 hwstatus_set(mem, hw_status & ~INTEL_RNG_ENABLED);
 207         else
 208                 printk(KERN_WARNING PFX "unusual: RNG already disabled\n");
 209 }
 210
 211
 212 static struct hwrng intel_rng = {
 213         .name           = "intel",
 214         .init           = intel_rng_init,
 215         .cleanup        = intel_rng_cleanup,
 216         .data_present   = intel_rng_data_present,
 217         .data_read      = intel_rng_data_read,
 218 };
 219
 220
 221 #ifdef CONFIG_SMP
 222 static char __initdata waitflag;
 223
 224 static void __init intel_init_wait(void *unused)
 225 {
 226         while (waitflag)
 227                 cpu_relax();
 228 }
 229 #endif
 230
 231 static int __init mod_init(void)
 232 {
 233         int err = -ENODEV;
 234         unsigned i;
 235         struct pci_dev *dev = NULL;
 236         void __iomem *mem;
 237         unsigned long flags;
 238         u8 bios_cntl_off, fwh_dec_en1_off;
 239         u8 bios_cntl_val = 0xff, fwh_dec_en1_val = 0xff;
 240         u8 hw_status, mfc, dvc;
 241
 242         for (i = 0; !dev && pci_tbl[i].vendor; ++i)
 243                 dev = pci_get_device(pci_tbl[i].vendor, pci_tbl[i].device, NULL);
 244
 245         if (!dev)
 246                 goto out; /* Device not found. */
 247
 248         if (no_fwh_detect < 0) {
 249                 pci_dev_put(dev);
 250                 goto fwh_done;
 251         }
 252
 253         /* Check for Intel 82802 */
 254         if (dev->device < 0x2640) {
 255                 fwh_dec_en1_off = FWH_DEC_EN1_REG_OLD;
 256                 bios_cntl_off = BIOS_CNTL_REG_OLD;
 257         } else {
 258                 fwh_dec_en1_off = FWH_DEC_EN1_REG_NEW;
 259                 bios_cntl_off = BIOS_CNTL_REG_NEW;
 260         }
 261
 262         pci_read_config_byte(dev, fwh_dec_en1_off, &fwh_dec_en1_val);
 263         pci_read_config_byte(dev, bios_cntl_off, &bios_cntl_val);
 264
 265         if ((bios_cntl_val &
 266              (BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK))
 267             == BIOS_CNTL_LOCK_ENABLE_MASK) {
 268                 static __initdata /*const*/ char warning[] =
 269                         KERN_WARNING PFX "Firmware space is locked read-only. If you can't or\n"
 270                         KERN_WARNING PFX "don't want to disable this in firmware setup, and if\n"
 271                         KERN_WARNING PFX "you are certain that your system has a functional\n"
 272                         KERN_WARNING PFX "RNG, try using the 'no_fwh_detect' option.\n";
 273
 274                 pci_dev_put(dev);
 275                 if (no_fwh_detect)
 276                         goto fwh_done;
 277                 printk(warning);
 278                 err = -EBUSY;
 279                 goto out;
 280         }
 281
 282         mem = ioremap_nocache(INTEL_FWH_ADDR, INTEL_FWH_ADDR_LEN);
 283         if (mem == NULL) {
 284                 pci_dev_put(dev);
 285                 err = -EBUSY;
 286                 goto out;
 287         }
 288
 289         /*
 290          * Since the BIOS code/data is going to disappear from its normal
 291          * location with the Read ID command, all activity on the system
 292          * must be stopped until the state is back to normal.
 293          */
 294 #ifdef CONFIG_SMP
 295         set_mb(waitflag, 1);
 296         if (smp_call_function(intel_init_wait, NULL, 1, 0) != 0) {
 297                 set_mb(waitflag, 0);
 298                 pci_dev_put(dev);
 299                 printk(KERN_ERR PFX "cannot run on all processors\n");
 300                 err = -EAGAIN;
 301                 goto err_unmap;
 302         }
 303 #endif
 304         local_irq_save(flags);
 305
 306         if (!(fwh_dec_en1_val & FWH_F8_EN_MASK))
 307                 pci_write_config_byte(dev,
 308                                       fwh_dec_en1_off,
 309                                       fwh_dec_en1_val | FWH_F8_EN_MASK);
 310         if (!(bios_cntl_val & BIOS_CNTL_WRITE_ENABLE_MASK))
 311                 pci_write_config_byte(dev,
 312                                       bios_cntl_off,
 313                                       bios_cntl_val | BIOS_CNTL_WRITE_ENABLE_MASK);
 314
 315         writeb(INTEL_FWH_RESET_CMD, mem);
 316         writeb(INTEL_FWH_READ_ID_CMD, mem);
 317         mfc = readb(mem + INTEL_FWH_MANUFACTURER_CODE_ADDRESS);
 318         dvc = readb(mem + INTEL_FWH_DEVICE_CODE_ADDRESS);
 319         writeb(INTEL_FWH_RESET_CMD, mem);
 320
 321         if (!(bios_cntl_val &
 322               (BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK)))
 323                 pci_write_config_byte(dev, bios_cntl_off, bios_cntl_val);
 324         if (!(fwh_dec_en1_val & FWH_F8_EN_MASK))
 325                 pci_write_config_byte(dev, fwh_dec_en1_off, fwh_dec_en1_val);
 326
 327         local_irq_restore(flags);
 328 #ifdef CONFIG_SMP
 329         /* Tell other CPUs to resume. */
 330         set_mb(waitflag, 0);
 331 #endif
 332
 333         iounmap(mem);
 334         pci_dev_put(dev);
 335
 336         if (mfc != INTEL_FWH_MANUFACTURER_CODE ||
 337             (dvc != INTEL_FWH_DEVICE_CODE_8M &&
 338              dvc != INTEL_FWH_DEVICE_CODE_4M)) {
 339                 printk(KERN_ERR PFX "FWH not detected\n");
 340                 err = -ENODEV;
 341                 goto out;
 342         }
 343
 344 fwh_done:
 345
 346         err = -ENOMEM;
 347         mem = ioremap(INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
 348         if (!mem)
 349                 goto out;
 350         intel_rng.priv = (unsigned long)mem;
 351
 352         /* Check for Random Number Generator */
 353         err = -ENODEV;
 354         hw_status = hwstatus_get(mem);
 355         if ((hw_status & INTEL_RNG_PRESENT) == 0)
 356                 goto err_unmap;
 357
 358         printk(KERN_INFO "Intel 82802 RNG detected\n");
 359         err = hwrng_register(&intel_rng);
 360         if (err) {
 361                 printk(KERN_ERR PFX "RNG registering failed (%d)\n",
 362                        err);
 363                 goto err_unmap;
 364         }
 365 out:
 366         return err;
 367
 368 err_unmap:
 369         iounmap(mem);
 370         goto out;
 371 }
 372
 373 static void __exit mod_exit(void)
 374 {
 375         void __iomem *mem = (void __iomem *)intel_rng.priv;
 376
 377         hwrng_unregister(&intel_rng);
 378         iounmap(mem);
 379 }
 380
 381 module_init(mod_init);
 382 module_exit(mod_exit);
 383
 384 MODULE_DESCRIPTION("H/W RNG driver for Intel chipsets");
 385 MODULE_LICENSE("GPL");