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
  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/hw_random.h>
  28 #include <linux/kernel.h>
  29 #include <linux/module.h>
  30 #include <linux/pci.h>
  31 #include <linux/stop_machine.h>
  32 #include <linux/delay.h>
  33 #include <linux/slab.h>
  34 #include <asm/io.h>
  35
  36
  37 #define PFX     KBUILD_MODNAME ": "
  38
  39 /*
  40  * RNG registers
  41  */
  42 #define INTEL_RNG_HW_STATUS                     0
  43 #define         INTEL_RNG_PRESENT               0x40
  44 #define         INTEL_RNG_ENABLED               0x01
  45 #define INTEL_RNG_STATUS                        1
  46 #define         INTEL_RNG_DATA_PRESENT          0x01
  47 #define INTEL_RNG_DATA                          2
  48
  49 /*
  50  * Magic address at which Intel PCI bridges locate the RNG
  51  */
  52 #define INTEL_RNG_ADDR                          0xFFBC015F
  53 #define INTEL_RNG_ADDR_LEN                      3
  54
  55 /*
  56  * LPC bridge PCI config space registers
  57  */
  58 #define FWH_DEC_EN1_REG_OLD                     0xe3
  59 #define FWH_DEC_EN1_REG_NEW                     0xd9 /* high byte of 16-bit register */
  60 #define FWH_F8_EN_MASK                          0x80
  61
  62 #define BIOS_CNTL_REG_OLD                       0x4e
  63 #define BIOS_CNTL_REG_NEW                       0xdc
  64 #define BIOS_CNTL_WRITE_ENABLE_MASK             0x01
  65 #define BIOS_CNTL_LOCK_ENABLE_MASK              0x02
  66
  67 /*
  68  * Magic address at which Intel Firmware Hubs get accessed
  69  */
  70 #define INTEL_FWH_ADDR                          0xffff0000
  71 #define INTEL_FWH_ADDR_LEN                      2
  72
  73 /*
  74  * Intel Firmware Hub command codes (write to any address inside the device)
  75  */
  76 #define INTEL_FWH_RESET_CMD                     0xff /* aka READ_ARRAY */
  77 #define INTEL_FWH_READ_ID_CMD                   0x90
  78
  79 /*
  80  * Intel Firmware Hub Read ID command result addresses
  81  */
  82 #define INTEL_FWH_MANUFACTURER_CODE_ADDRESS     0x000000
  83 #define INTEL_FWH_DEVICE_CODE_ADDRESS           0x000001
  84
  85 /*
  86  * Intel Firmware Hub Read ID command result values
  87  */
  88 #define INTEL_FWH_MANUFACTURER_CODE             0x89
  89 #define INTEL_FWH_DEVICE_CODE_8M                0xac
  90 #define INTEL_FWH_DEVICE_CODE_4M                0xad
  91
  92 /*
  93  * Data for PCI driver interface
  94  *
  95  * This data only exists for exporting the supported
  96  * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
  97  * register a pci_driver, because someone else might one day
  98  * want to register another driver on the same PCI id.
  99  */
 100 static const struct pci_device_id pci_tbl[] = {
 101 /* AA
 102         { PCI_DEVICE(0x8086, 0x2418) }, */
 103         { PCI_DEVICE(0x8086, 0x2410) }, /* AA */
 104 /* AB
 105         { PCI_DEVICE(0x8086, 0x2428) }, */
 106         { PCI_DEVICE(0x8086, 0x2420) }, /* AB */
 107 /* ??
 108         { PCI_DEVICE(0x8086, 0x2430) }, */
 109 /* BAM, CAM, DBM, FBM, GxM
 110         { PCI_DEVICE(0x8086, 0x2448) }, */
 111         { PCI_DEVICE(0x8086, 0x244c) }, /* BAM */
 112         { PCI_DEVICE(0x8086, 0x248c) }, /* CAM */
 113         { PCI_DEVICE(0x8086, 0x24cc) }, /* DBM */
 114         { PCI_DEVICE(0x8086, 0x2641) }, /* FBM */
 115         { PCI_DEVICE(0x8086, 0x27b9) }, /* GxM */
 116         { PCI_DEVICE(0x8086, 0x27bd) }, /* GxM DH */
 117 /* BA, CA, DB, Ex, 6300, Fx, 631x/632x, Gx
 118         { PCI_DEVICE(0x8086, 0x244e) }, */
 119         { PCI_DEVICE(0x8086, 0x2440) }, /* BA */
 120         { PCI_DEVICE(0x8086, 0x2480) }, /* CA */
 121         { PCI_DEVICE(0x8086, 0x24c0) }, /* DB */
 122         { PCI_DEVICE(0x8086, 0x24d0) }, /* Ex */
 123         { PCI_DEVICE(0x8086, 0x25a1) }, /* 6300 */
 124         { PCI_DEVICE(0x8086, 0x2640) }, /* Fx */
 125         { PCI_DEVICE(0x8086, 0x2670) }, /* 631x/632x */
 126         { PCI_DEVICE(0x8086, 0x2671) }, /* 631x/632x */
 127         { PCI_DEVICE(0x8086, 0x2672) }, /* 631x/632x */
 128         { PCI_DEVICE(0x8086, 0x2673) }, /* 631x/632x */
 129         { PCI_DEVICE(0x8086, 0x2674) }, /* 631x/632x */
 130         { PCI_DEVICE(0x8086, 0x2675) }, /* 631x/632x */
 131         { PCI_DEVICE(0x8086, 0x2676) }, /* 631x/632x */
 132         { PCI_DEVICE(0x8086, 0x2677) }, /* 631x/632x */
 133         { PCI_DEVICE(0x8086, 0x2678) }, /* 631x/632x */
 134         { PCI_DEVICE(0x8086, 0x2679) }, /* 631x/632x */
 135         { PCI_DEVICE(0x8086, 0x267a) }, /* 631x/632x */
 136         { PCI_DEVICE(0x8086, 0x267b) }, /* 631x/632x */
 137         { PCI_DEVICE(0x8086, 0x267c) }, /* 631x/632x */
 138         { PCI_DEVICE(0x8086, 0x267d) }, /* 631x/632x */
 139         { PCI_DEVICE(0x8086, 0x267e) }, /* 631x/632x */
 140         { PCI_DEVICE(0x8086, 0x267f) }, /* 631x/632x */
 141         { PCI_DEVICE(0x8086, 0x27b8) }, /* Gx */
 142 /* E
 143         { PCI_DEVICE(0x8086, 0x245e) }, */
 144         { PCI_DEVICE(0x8086, 0x2450) }, /* E  */
 145         { 0, }, /* terminate list */
 146 };
 147 MODULE_DEVICE_TABLE(pci, pci_tbl);
 148
 149 static __initdata int no_fwh_detect;
 150 module_param(no_fwh_detect, int, 0);
 151 MODULE_PARM_DESC(no_fwh_detect, "Skip FWH detection:\n"
 152                                 " positive value - skip if FWH space locked read-only\n"
 153                                 " negative value - skip always");
 154
 155 static inline u8 hwstatus_get(void __iomem *mem)
 156 {
 157         return readb(mem + INTEL_RNG_HW_STATUS);
 158 }
 159
 160 static inline u8 hwstatus_set(void __iomem *mem,
 161                               u8 hw_status)
 162 {
 163         writeb(hw_status, mem + INTEL_RNG_HW_STATUS);
 164         return hwstatus_get(mem);
 165 }
 166
 167 static int intel_rng_data_present(struct hwrng *rng, int wait)
 168 {
 169         void __iomem *mem = (void __iomem *)rng->priv;
 170         int data, i;
 171
 172         for (i = 0; i < 20; i++) {
 173                 data = !!(readb(mem + INTEL_RNG_STATUS) &
 174                           INTEL_RNG_DATA_PRESENT);
 175                 if (data || !wait)
 176                         break;
 177                 udelay(10);
 178         }
 179         return data;
 180 }
 181
 182 static int intel_rng_data_read(struct hwrng *rng, u32 *data)
 183 {
 184         void __iomem *mem = (void __iomem *)rng->priv;
 185
 186         *data = readb(mem + INTEL_RNG_DATA);
 187
 188         return 1;
 189 }
 190
 191 static int intel_rng_init(struct hwrng *rng)
 192 {
 193         void __iomem *mem = (void __iomem *)rng->priv;
 194         u8 hw_status;
 195         int err = -EIO;
 196
 197         hw_status = hwstatus_get(mem);
 198         /* turn RNG h/w on, if it's off */
 199         if ((hw_status & INTEL_RNG_ENABLED) == 0)
 200                 hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED);
 201         if ((hw_status & INTEL_RNG_ENABLED) == 0) {
 202                 pr_err(PFX "cannot enable RNG, aborting\n");
 203                 goto out;
 204         }
 205         err = 0;
 206 out:
 207         return err;
 208 }
 209
 210 static void intel_rng_cleanup(struct hwrng *rng)
 211 {
 212         void __iomem *mem = (void __iomem *)rng->priv;
 213         u8 hw_status;
 214
 215         hw_status = hwstatus_get(mem);
 216         if (hw_status & INTEL_RNG_ENABLED)
 217                 hwstatus_set(mem, hw_status & ~INTEL_RNG_ENABLED);
 218         else
 219                 pr_warn(PFX "unusual: RNG already disabled\n");
 220 }
 221
 222
 223 static struct hwrng intel_rng = {
 224         .name           = "intel",
 225         .init           = intel_rng_init,
 226         .cleanup        = intel_rng_cleanup,
 227         .data_present   = intel_rng_data_present,
 228         .data_read      = intel_rng_data_read,
 229 };
 230
 231 struct intel_rng_hw {
 232         struct pci_dev *dev;
 233         void __iomem *mem;
 234         u8 bios_cntl_off;
 235         u8 bios_cntl_val;
 236         u8 fwh_dec_en1_off;
 237         u8 fwh_dec_en1_val;
 238 };
 239
 240 static int __init intel_rng_hw_init(void *_intel_rng_hw)
 241 {
 242         struct intel_rng_hw *intel_rng_hw = _intel_rng_hw;
 243         u8 mfc, dvc;
 244
 245         /* interrupts disabled in stop_machine call */
 246
 247         if (!(intel_rng_hw->fwh_dec_en1_val & FWH_F8_EN_MASK))
 248                 pci_write_config_byte(intel_rng_hw->dev,
 249                                       intel_rng_hw->fwh_dec_en1_off,
 250                                       intel_rng_hw->fwh_dec_en1_val |
 251                                       FWH_F8_EN_MASK);
 252         if (!(intel_rng_hw->bios_cntl_val & BIOS_CNTL_WRITE_ENABLE_MASK))
 253                 pci_write_config_byte(intel_rng_hw->dev,
 254                                       intel_rng_hw->bios_cntl_off,
 255                                       intel_rng_hw->bios_cntl_val |
 256                                       BIOS_CNTL_WRITE_ENABLE_MASK);
 257
 258         writeb(INTEL_FWH_RESET_CMD, intel_rng_hw->mem);
 259         writeb(INTEL_FWH_READ_ID_CMD, intel_rng_hw->mem);
 260         mfc = readb(intel_rng_hw->mem + INTEL_FWH_MANUFACTURER_CODE_ADDRESS);
 261         dvc = readb(intel_rng_hw->mem + INTEL_FWH_DEVICE_CODE_ADDRESS);
 262         writeb(INTEL_FWH_RESET_CMD, intel_rng_hw->mem);
 263
 264         if (!(intel_rng_hw->bios_cntl_val &
 265               (BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK)))
 266                 pci_write_config_byte(intel_rng_hw->dev,
 267                                       intel_rng_hw->bios_cntl_off,
 268                                       intel_rng_hw->bios_cntl_val);
 269         if (!(intel_rng_hw->fwh_dec_en1_val & FWH_F8_EN_MASK))
 270                 pci_write_config_byte(intel_rng_hw->dev,
 271                                       intel_rng_hw->fwh_dec_en1_off,
 272                                       intel_rng_hw->fwh_dec_en1_val);
 273
 274         if (mfc != INTEL_FWH_MANUFACTURER_CODE ||
 275             (dvc != INTEL_FWH_DEVICE_CODE_8M &&
 276              dvc != INTEL_FWH_DEVICE_CODE_4M)) {
 277                 pr_notice(PFX "FWH not detected\n");
 278                 return -ENODEV;
 279         }
 280
 281         return 0;
 282 }
 283
 284 static int __init intel_init_hw_struct(struct intel_rng_hw *intel_rng_hw,
 285                                         struct pci_dev *dev)
 286 {
 287         intel_rng_hw->bios_cntl_val = 0xff;
 288         intel_rng_hw->fwh_dec_en1_val = 0xff;
 289         intel_rng_hw->dev = dev;
 290
 291         /* Check for Intel 82802 */
 292         if (dev->device < 0x2640) {
 293                 intel_rng_hw->fwh_dec_en1_off = FWH_DEC_EN1_REG_OLD;
 294                 intel_rng_hw->bios_cntl_off = BIOS_CNTL_REG_OLD;
 295         } else {
 296                 intel_rng_hw->fwh_dec_en1_off = FWH_DEC_EN1_REG_NEW;
 297                 intel_rng_hw->bios_cntl_off = BIOS_CNTL_REG_NEW;
 298         }
 299
 300         pci_read_config_byte(dev, intel_rng_hw->fwh_dec_en1_off,
 301                              &intel_rng_hw->fwh_dec_en1_val);
 302         pci_read_config_byte(dev, intel_rng_hw->bios_cntl_off,
 303                              &intel_rng_hw->bios_cntl_val);
 304
 305         if ((intel_rng_hw->bios_cntl_val &
 306              (BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK))
 307             == BIOS_CNTL_LOCK_ENABLE_MASK) {
 308                 static __initdata /*const*/ char warning[] =
 309 PFX "Firmware space is locked read-only. If you can't or\n"
 310 PFX "don't want to disable this in firmware setup, and if\n"
 311 PFX "you are certain that your system has a functional\n"
 312 PFX "RNG, try using the 'no_fwh_detect' option.\n";
 313
 314                 if (no_fwh_detect)
 315                         return -ENODEV;
 316                 pr_warn("%s", warning);
 317                 return -EBUSY;
 318         }
 319
 320         intel_rng_hw->mem = ioremap(INTEL_FWH_ADDR, INTEL_FWH_ADDR_LEN);
 321         if (intel_rng_hw->mem == NULL)
 322                 return -EBUSY;
 323
 324         return 0;
 325 }
 326
 327
 328 static int __init mod_init(void)
 329 {
 330         int err = -ENODEV;
 331         int i;
 332         struct pci_dev *dev = NULL;
 333         void __iomem *mem = mem;
 334         u8 hw_status;
 335         struct intel_rng_hw *intel_rng_hw;
 336
 337         for (i = 0; !dev && pci_tbl[i].vendor; ++i)
 338                 dev = pci_get_device(pci_tbl[i].vendor, pci_tbl[i].device,
 339                                      NULL);
 340
 341         if (!dev)
 342                 goto out; /* Device not found. */
 343
 344         if (no_fwh_detect < 0) {
 345                 pci_dev_put(dev);
 346                 goto fwh_done;
 347         }
 348
 349         intel_rng_hw = kmalloc(sizeof(*intel_rng_hw), GFP_KERNEL);
 350         if (!intel_rng_hw) {
 351                 pci_dev_put(dev);
 352                 goto out;
 353         }
 354
 355         err = intel_init_hw_struct(intel_rng_hw, dev);
 356         if (err) {
 357                 pci_dev_put(dev);
 358                 kfree(intel_rng_hw);
 359                 if (err == -ENODEV)
 360                         goto fwh_done;
 361                 goto out;
 362         }
 363
 364         /*
 365          * Since the BIOS code/data is going to disappear from its normal
 366          * location with the Read ID command, all activity on the system
 367          * must be stopped until the state is back to normal.
 368          *
 369          * Use stop_machine because IPIs can be blocked by disabling
 370          * interrupts.
 371          */
 372         err = stop_machine(intel_rng_hw_init, intel_rng_hw, NULL);
 373         pci_dev_put(dev);
 374         iounmap(intel_rng_hw->mem);
 375         kfree(intel_rng_hw);
 376         if (err)
 377                 goto out;
 378
 379 fwh_done:
 380         err = -ENOMEM;
 381         mem = ioremap(INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
 382         if (!mem)
 383                 goto out;
 384         intel_rng.priv = (unsigned long)mem;
 385
 386         /* Check for Random Number Generator */
 387         err = -ENODEV;
 388         hw_status = hwstatus_get(mem);
 389         if ((hw_status & INTEL_RNG_PRESENT) == 0) {
 390                 iounmap(mem);
 391                 goto out;
 392         }
 393
 394         pr_info("Intel 82802 RNG detected\n");
 395         err = hwrng_register(&intel_rng);
 396         if (err) {
 397                 pr_err(PFX "RNG registering failed (%d)\n",
 398                        err);
 399                 iounmap(mem);
 400         }
 401 out:
 402         return err;
 403
 404 }
 405
 406 static void __exit mod_exit(void)
 407 {
 408         void __iomem *mem = (void __iomem *)intel_rng.priv;
 409
 410         hwrng_unregister(&intel_rng);
 411         iounmap(mem);
 412 }
 413
 414 module_init(mod_init);
 415 module_exit(mod_exit);
 416
 417 MODULE_DESCRIPTION("H/W RNG driver for Intel chipsets");
 418 MODULE_LICENSE("GPL");