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