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