arch/powerpc/platforms/powermac/nvram.c

   1 /*
   2  *  Copyright (C) 2002 Benjamin Herrenschmidt (benh@kernel.crashing.org)
   3  *
   4  *  This program is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU General Public License
   6  *  as published by the Free Software Foundation; either version
   7  *  2 of the License, or (at your option) any later version.
   8  *
   9  *  Todo: - add support for the OF persistent properties
  10  */
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/stddef.h>
  14 #include <linux/string.h>
  15 #include <linux/nvram.h>
  16 #include <linux/init.h>
  17 #include <linux/delay.h>
  18 #include <linux/errno.h>
  19 #include <linux/adb.h>
  20 #include <linux/pmu.h>
  21 #include <linux/bootmem.h>
  22 #include <linux/completion.h>
  23 #include <linux/spinlock.h>
  24 #include <asm/sections.h>
  25 #include <asm/io.h>
  26 #include <asm/system.h>
  27 #include <asm/prom.h>
  28 #include <asm/machdep.h>
  29 #include <asm/nvram.h>
  30
  31 #include "pmac.h"
  32
  33 #define DEBUG
  34
  35 #ifdef DEBUG
  36 #define DBG(x...) printk(x)
  37 #else
  38 #define DBG(x...)
  39 #endif
  40
  41 #define NVRAM_SIZE              0x2000  /* 8kB of non-volatile RAM */
  42
  43 #define CORE99_SIGNATURE        0x5a
  44 #define CORE99_ADLER_START      0x14
  45
  46 /* On Core99, nvram is either a sharp, a micron or an AMD flash */
  47 #define SM_FLASH_STATUS_DONE    0x80
  48 #define SM_FLASH_STATUS_ERR     0x38
  49
  50 #define SM_FLASH_CMD_ERASE_CONFIRM      0xd0
  51 #define SM_FLASH_CMD_ERASE_SETUP        0x20
  52 #define SM_FLASH_CMD_RESET              0xff
  53 #define SM_FLASH_CMD_WRITE_SETUP        0x40
  54 #define SM_FLASH_CMD_CLEAR_STATUS       0x50
  55 #define SM_FLASH_CMD_READ_STATUS        0x70
  56
  57 /* CHRP NVRAM header */
  58 struct chrp_header {
  59   u8            signature;
  60   u8            cksum;
  61   u16           len;
  62   char          name[12];
  63   u8            data[0];
  64 };
  65
  66 struct core99_header {
  67   struct chrp_header    hdr;
  68   u32                   adler;
  69   u32                   generation;
  70   u32                   reserved[2];
  71 };
  72
  73 /*
  74  * Read and write the non-volatile RAM on PowerMacs and CHRP machines.
  75  */
  76 static int nvram_naddrs;
  77 static volatile unsigned char __iomem *nvram_data;
  78 static int is_core_99;
  79 static int core99_bank = 0;
  80 static int nvram_partitions[3];
  81 // XXX Turn that into a sem
  82 static DEFINE_RAW_SPINLOCK(nv_lock);
  83
  84 static int (*core99_write_bank)(int bank, u8* datas);
  85 static int (*core99_erase_bank)(int bank);
  86
  87 static char *nvram_image;
  88
  89
  90 static unsigned char core99_nvram_read_byte(int addr)
  91 {
  92         if (nvram_image == NULL)
  93                 return 0xff;
  94         return nvram_image[addr];
  95 }
  96
  97 static void core99_nvram_write_byte(int addr, unsigned char val)
  98 {
  99         if (nvram_image == NULL)
 100                 return;
 101         nvram_image[addr] = val;
 102 }
 103
 104 static ssize_t core99_nvram_read(char *buf, size_t count, loff_t *index)
 105 {
 106         int i;
 107
 108         if (nvram_image == NULL)
 109                 return -ENODEV;
 110         if (*index > NVRAM_SIZE)
 111                 return 0;
 112
 113         i = *index;
 114         if (i + count > NVRAM_SIZE)
 115                 count = NVRAM_SIZE - i;
 116
 117         memcpy(buf, &nvram_image[i], count);
 118         *index = i + count;
 119         return count;
 120 }
 121
 122 static ssize_t core99_nvram_write(char *buf, size_t count, loff_t *index)
 123 {
 124         int i;
 125
 126         if (nvram_image == NULL)
 127                 return -ENODEV;
 128         if (*index > NVRAM_SIZE)
 129                 return 0;
 130
 131         i = *index;
 132         if (i + count > NVRAM_SIZE)
 133                 count = NVRAM_SIZE - i;
 134
 135         memcpy(&nvram_image[i], buf, count);
 136         *index = i + count;
 137         return count;
 138 }
 139
 140 static ssize_t core99_nvram_size(void)
 141 {
 142         if (nvram_image == NULL)
 143                 return -ENODEV;
 144         return NVRAM_SIZE;
 145 }
 146
 147 #ifdef CONFIG_PPC32
 148 static volatile unsigned char __iomem *nvram_addr;
 149 static int nvram_mult;
 150
 151 static unsigned char direct_nvram_read_byte(int addr)
 152 {
 153         return in_8(&nvram_data[(addr & (NVRAM_SIZE - 1)) * nvram_mult]);
 154 }
 155
 156 static void direct_nvram_write_byte(int addr, unsigned char val)
 157 {
 158         out_8(&nvram_data[(addr & (NVRAM_SIZE - 1)) * nvram_mult], val);
 159 }
 160
 161
 162 static unsigned char indirect_nvram_read_byte(int addr)
 163 {
 164         unsigned char val;
 165         unsigned long flags;
 166
 167         raw_spin_lock_irqsave(&nv_lock, flags);
 168         out_8(nvram_addr, addr >> 5);
 169         val = in_8(&nvram_data[(addr & 0x1f) << 4]);
 170         raw_spin_unlock_irqrestore(&nv_lock, flags);
 171
 172         return val;
 173 }
 174
 175 static void indirect_nvram_write_byte(int addr, unsigned char val)
 176 {
 177         unsigned long flags;
 178
 179         raw_spin_lock_irqsave(&nv_lock, flags);
 180         out_8(nvram_addr, addr >> 5);
 181         out_8(&nvram_data[(addr & 0x1f) << 4], val);
 182         raw_spin_unlock_irqrestore(&nv_lock, flags);
 183 }
 184
 185
 186 #ifdef CONFIG_ADB_PMU
 187
 188 static void pmu_nvram_complete(struct adb_request *req)
 189 {
 190         if (req->arg)
 191                 complete((struct completion *)req->arg);
 192 }
 193
 194 static unsigned char pmu_nvram_read_byte(int addr)
 195 {
 196         struct adb_request req;
 197         DECLARE_COMPLETION_ONSTACK(req_complete);
 198
 199         req.arg = system_state == SYSTEM_RUNNING ? &req_complete : NULL;
 200         if (pmu_request(&req, pmu_nvram_complete, 3, PMU_READ_NVRAM,
 201                         (addr >> 8) & 0xff, addr & 0xff))
 202                 return 0xff;
 203         if (system_state == SYSTEM_RUNNING)
 204                 wait_for_completion(&req_complete);
 205         while (!req.complete)
 206                 pmu_poll();
 207         return req.reply[0];
 208 }
 209
 210 static void pmu_nvram_write_byte(int addr, unsigned char val)
 211 {
 212         struct adb_request req;
 213         DECLARE_COMPLETION_ONSTACK(req_complete);
 214
 215         req.arg = system_state == SYSTEM_RUNNING ? &req_complete : NULL;
 216         if (pmu_request(&req, pmu_nvram_complete, 4, PMU_WRITE_NVRAM,
 217                         (addr >> 8) & 0xff, addr & 0xff, val))
 218                 return;
 219         if (system_state == SYSTEM_RUNNING)
 220                 wait_for_completion(&req_complete);
 221         while (!req.complete)
 222                 pmu_poll();
 223 }
 224
 225 #endif /* CONFIG_ADB_PMU */
 226 #endif /* CONFIG_PPC32 */
 227
 228 static u8 chrp_checksum(struct chrp_header* hdr)
 229 {
 230         u8 *ptr;
 231         u16 sum = hdr->signature;
 232         for (ptr = (u8 *)&hdr->len; ptr < hdr->data; ptr++)
 233                 sum += *ptr;
 234         while (sum > 0xFF)
 235                 sum = (sum & 0xFF) + (sum>>8);
 236         return sum;
 237 }
 238
 239 static u32 core99_calc_adler(u8 *buffer)
 240 {
 241         int cnt;
 242         u32 low, high;
 243
 244         buffer += CORE99_ADLER_START;
 245         low = 1;
 246         high = 0;
 247         for (cnt=0; cnt<(NVRAM_SIZE-CORE99_ADLER_START); cnt++) {
 248                 if ((cnt % 5000) == 0) {
 249                         high  %= 65521UL;
 250                         high %= 65521UL;
 251                 }
 252                 low += buffer[cnt];
 253                 high += low;
 254         }
 255         low  %= 65521UL;
 256         high %= 65521UL;
 257
 258         return (high << 16) | low;
 259 }
 260
 261 static u32 core99_check(u8* datas)
 262 {
 263         struct core99_header* hdr99 = (struct core99_header*)datas;
 264
 265         if (hdr99->hdr.signature != CORE99_SIGNATURE) {
 266                 DBG("Invalid signature\n");
 267                 return 0;
 268         }
 269         if (hdr99->hdr.cksum != chrp_checksum(&hdr99->hdr)) {
 270                 DBG("Invalid checksum\n");
 271                 return 0;
 272         }
 273         if (hdr99->adler != core99_calc_adler(datas)) {
 274                 DBG("Invalid adler\n");
 275                 return 0;
 276         }
 277         return hdr99->generation;
 278 }
 279
 280 static int sm_erase_bank(int bank)
 281 {
 282         int stat, i;
 283         unsigned long timeout;
 284
 285         u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
 286
 287         DBG("nvram: Sharp/Micron Erasing bank %d...\n", bank);
 288
 289         out_8(base, SM_FLASH_CMD_ERASE_SETUP);
 290         out_8(base, SM_FLASH_CMD_ERASE_CONFIRM);
 291         timeout = 0;
 292         do {
 293                 if (++timeout > 1000000) {
 294                         printk(KERN_ERR "nvram: Sharp/Micron flash erase timeout !\n");
 295                         break;
 296                 }
 297                 out_8(base, SM_FLASH_CMD_READ_STATUS);
 298                 stat = in_8(base);
 299         } while (!(stat & SM_FLASH_STATUS_DONE));
 300
 301         out_8(base, SM_FLASH_CMD_CLEAR_STATUS);
 302         out_8(base, SM_FLASH_CMD_RESET);
 303
 304         for (i=0; i<NVRAM_SIZE; i++)
 305                 if (base[i] != 0xff) {
 306                         printk(KERN_ERR "nvram: Sharp/Micron flash erase failed !\n");
 307                         return -ENXIO;
 308                 }
 309         return 0;
 310 }
 311
 312 static int sm_write_bank(int bank, u8* datas)
 313 {
 314         int i, stat = 0;
 315         unsigned long timeout;
 316
 317         u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
 318
 319         DBG("nvram: Sharp/Micron Writing bank %d...\n", bank);
 320
 321         for (i=0; i<NVRAM_SIZE; i++) {
 322                 out_8(base+i, SM_FLASH_CMD_WRITE_SETUP);
 323                 udelay(1);
 324                 out_8(base+i, datas[i]);
 325                 timeout = 0;
 326                 do {
 327                         if (++timeout > 1000000) {
 328                                 printk(KERN_ERR "nvram: Sharp/Micron flash write timeout !\n");
 329                                 break;
 330                         }
 331                         out_8(base, SM_FLASH_CMD_READ_STATUS);
 332                         stat = in_8(base);
 333                 } while (!(stat & SM_FLASH_STATUS_DONE));
 334                 if (!(stat & SM_FLASH_STATUS_DONE))
 335                         break;
 336         }
 337         out_8(base, SM_FLASH_CMD_CLEAR_STATUS);
 338         out_8(base, SM_FLASH_CMD_RESET);
 339         for (i=0; i<NVRAM_SIZE; i++)
 340                 if (base[i] != datas[i]) {
 341                         printk(KERN_ERR "nvram: Sharp/Micron flash write failed !\n");
 342                         return -ENXIO;
 343                 }
 344         return 0;
 345 }
 346
 347 static int amd_erase_bank(int bank)
 348 {
 349         int i, stat = 0;
 350         unsigned long timeout;
 351
 352         u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
 353
 354         DBG("nvram: AMD Erasing bank %d...\n", bank);
 355
 356         /* Unlock 1 */
 357         out_8(base+0x555, 0xaa);
 358         udelay(1);
 359         /* Unlock 2 */
 360         out_8(base+0x2aa, 0x55);
 361         udelay(1);
 362
 363         /* Sector-Erase */
 364         out_8(base+0x555, 0x80);
 365         udelay(1);
 366         out_8(base+0x555, 0xaa);
 367         udelay(1);
 368         out_8(base+0x2aa, 0x55);
 369         udelay(1);
 370         out_8(base, 0x30);
 371         udelay(1);
 372
 373         timeout = 0;
 374         do {
 375                 if (++timeout > 1000000) {
 376                         printk(KERN_ERR "nvram: AMD flash erase timeout !\n");
 377                         break;
 378                 }
 379                 stat = in_8(base) ^ in_8(base);
 380         } while (stat != 0);
 381
 382         /* Reset */
 383         out_8(base, 0xf0);
 384         udelay(1);
 385
 386         for (i=0; i<NVRAM_SIZE; i++)
 387                 if (base[i] != 0xff) {
 388                         printk(KERN_ERR "nvram: AMD flash erase failed !\n");
 389                         return -ENXIO;
 390                 }
 391         return 0;
 392 }
 393
 394 static int amd_write_bank(int bank, u8* datas)
 395 {
 396         int i, stat = 0;
 397         unsigned long timeout;
 398
 399         u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
 400
 401         DBG("nvram: AMD Writing bank %d...\n", bank);
 402
 403         for (i=0; i<NVRAM_SIZE; i++) {
 404                 /* Unlock 1 */
 405                 out_8(base+0x555, 0xaa);
 406                 udelay(1);
 407                 /* Unlock 2 */
 408                 out_8(base+0x2aa, 0x55);
 409                 udelay(1);
 410
 411                 /* Write single word */
 412                 out_8(base+0x555, 0xa0);
 413                 udelay(1);
 414                 out_8(base+i, datas[i]);
 415
 416                 timeout = 0;
 417                 do {
 418                         if (++timeout > 1000000) {
 419                                 printk(KERN_ERR "nvram: AMD flash write timeout !\n");
 420                                 break;
 421                         }
 422                         stat = in_8(base) ^ in_8(base);
 423                 } while (stat != 0);
 424                 if (stat != 0)
 425                         break;
 426         }
 427
 428         /* Reset */
 429         out_8(base, 0xf0);
 430         udelay(1);
 431
 432         for (i=0; i<NVRAM_SIZE; i++)
 433                 if (base[i] != datas[i]) {
 434                         printk(KERN_ERR "nvram: AMD flash write failed !\n");
 435                         return -ENXIO;
 436                 }
 437         return 0;
 438 }
 439
 440 static void __init lookup_partitions(void)
 441 {
 442         u8 buffer[17];
 443         int i, offset;
 444         struct chrp_header* hdr;
 445
 446         if (pmac_newworld) {
 447                 nvram_partitions[pmac_nvram_OF] = -1;
 448                 nvram_partitions[pmac_nvram_XPRAM] = -1;
 449                 nvram_partitions[pmac_nvram_NR] = -1;
 450                 hdr = (struct chrp_header *)buffer;
 451
 452                 offset = 0;
 453                 buffer[16] = 0;
 454                 do {
 455                         for (i=0;i<16;i++)
 456                                 buffer[i] = ppc_md.nvram_read_val(offset+i);
 457                         if (!strcmp(hdr->name, "common"))
 458                                 nvram_partitions[pmac_nvram_OF] = offset + 0x10;
 459                         if (!strcmp(hdr->name, "APL,MacOS75")) {
 460                                 nvram_partitions[pmac_nvram_XPRAM] = offset + 0x10;
 461                                 nvram_partitions[pmac_nvram_NR] = offset + 0x110;
 462                         }
 463                         offset += (hdr->len * 0x10);
 464                 } while(offset < NVRAM_SIZE);
 465         } else {
 466                 nvram_partitions[pmac_nvram_OF] = 0x1800;
 467                 nvram_partitions[pmac_nvram_XPRAM] = 0x1300;
 468                 nvram_partitions[pmac_nvram_NR] = 0x1400;
 469         }
 470         DBG("nvram: OF partition at 0x%x\n", nvram_partitions[pmac_nvram_OF]);
 471         DBG("nvram: XP partition at 0x%x\n", nvram_partitions[pmac_nvram_XPRAM]);
 472         DBG("nvram: NR partition at 0x%x\n", nvram_partitions[pmac_nvram_NR]);
 473 }
 474
 475 static void core99_nvram_sync(void)
 476 {
 477         struct core99_header* hdr99;
 478         unsigned long flags;
 479
 480         if (!is_core_99 || !nvram_data || !nvram_image)
 481                 return;
 482
 483         raw_spin_lock_irqsave(&nv_lock, flags);
 484         if (!memcmp(nvram_image, (u8*)nvram_data + core99_bank*NVRAM_SIZE,
 485                 NVRAM_SIZE))
 486                 goto bail;
 487
 488         DBG("Updating nvram...\n");
 489
 490         hdr99 = (struct core99_header*)nvram_image;
 491         hdr99->generation++;
 492         hdr99->hdr.signature = CORE99_SIGNATURE;
 493         hdr99->hdr.cksum = chrp_checksum(&hdr99->hdr);
 494         hdr99->adler = core99_calc_adler(nvram_image);
 495         core99_bank = core99_bank ? 0 : 1;
 496         if (core99_erase_bank)
 497                 if (core99_erase_bank(core99_bank)) {
 498                         printk("nvram: Error erasing bank %d\n", core99_bank);
 499                         goto bail;
 500                 }
 501         if (core99_write_bank)
 502                 if (core99_write_bank(core99_bank, nvram_image))
 503                         printk("nvram: Error writing bank %d\n", core99_bank);
 504  bail:
 505         raw_spin_unlock_irqrestore(&nv_lock, flags);
 506
 507 #ifdef DEBUG
 508         mdelay(2000);
 509 #endif
 510 }
 511
 512 static int __init core99_nvram_setup(struct device_node *dp, unsigned long addr)
 513 {
 514         int i;
 515         u32 gen_bank0, gen_bank1;
 516
 517         if (nvram_naddrs < 1) {
 518                 printk(KERN_ERR "nvram: no address\n");
 519                 return -EINVAL;
 520         }
 521         nvram_image = alloc_bootmem(NVRAM_SIZE);
 522         if (nvram_image == NULL) {
 523                 printk(KERN_ERR "nvram: can't allocate ram image\n");
 524                 return -ENOMEM;
 525         }
 526         nvram_data = ioremap(addr, NVRAM_SIZE*2);
 527         nvram_naddrs = 1; /* Make sure we get the correct case */
 528
 529         DBG("nvram: Checking bank 0...\n");
 530
 531         gen_bank0 = core99_check((u8 *)nvram_data);
 532         gen_bank1 = core99_check((u8 *)nvram_data + NVRAM_SIZE);
 533         core99_bank = (gen_bank0 < gen_bank1) ? 1 : 0;
 534
 535         DBG("nvram: gen0=%d, gen1=%d\n", gen_bank0, gen_bank1);
 536         DBG("nvram: Active bank is: %d\n", core99_bank);
 537
 538         for (i=0; i<NVRAM_SIZE; i++)
 539                 nvram_image[i] = nvram_data[i + core99_bank*NVRAM_SIZE];
 540
 541         ppc_md.nvram_read_val   = core99_nvram_read_byte;
 542         ppc_md.nvram_write_val  = core99_nvram_write_byte;
 543         ppc_md.nvram_read       = core99_nvram_read;
 544         ppc_md.nvram_write      = core99_nvram_write;
 545         ppc_md.nvram_size       = core99_nvram_size;
 546         ppc_md.nvram_sync       = core99_nvram_sync;
 547         ppc_md.machine_shutdown = core99_nvram_sync;
 548         /*
 549          * Maybe we could be smarter here though making an exclusive list
 550          * of known flash chips is a bit nasty as older OF didn't provide us
 551          * with a useful "compatible" entry. A solution would be to really
 552          * identify the chip using flash id commands and base ourselves on
 553          * a list of known chips IDs
 554          */
 555         if (of_device_is_compatible(dp, "amd-0137")) {
 556                 core99_erase_bank = amd_erase_bank;
 557                 core99_write_bank = amd_write_bank;
 558         } else {
 559                 core99_erase_bank = sm_erase_bank;
 560                 core99_write_bank = sm_write_bank;
 561         }
 562         return 0;
 563 }
 564
 565 int __init pmac_nvram_init(void)
 566 {
 567         struct device_node *dp;
 568         struct resource r1, r2;
 569         unsigned int s1 = 0, s2 = 0;
 570         int err = 0;
 571
 572         nvram_naddrs = 0;
 573
 574         dp = of_find_node_by_name(NULL, "nvram");
 575         if (dp == NULL) {
 576                 printk(KERN_ERR "Can't find NVRAM device\n");
 577                 return -ENODEV;
 578         }
 579
 580         /* Try to obtain an address */
 581         if (of_address_to_resource(dp, 0, &r1) == 0) {
 582                 nvram_naddrs = 1;
 583                 s1 = (r1.end - r1.start) + 1;
 584                 if (of_address_to_resource(dp, 1, &r2) == 0) {
 585                         nvram_naddrs = 2;
 586                         s2 = (r2.end - r2.start) + 1;
 587                 }
 588         }
 589
 590         is_core_99 = of_device_is_compatible(dp, "nvram,flash");
 591         if (is_core_99) {
 592                 err = core99_nvram_setup(dp, r1.start);
 593                 goto bail;
 594         }
 595
 596 #ifdef CONFIG_PPC32
 597         if (machine_is(chrp) && nvram_naddrs == 1) {
 598                 nvram_data = ioremap(r1.start, s1);
 599                 nvram_mult = 1;
 600                 ppc_md.nvram_read_val   = direct_nvram_read_byte;
 601                 ppc_md.nvram_write_val  = direct_nvram_write_byte;
 602         } else if (nvram_naddrs == 1) {
 603                 nvram_data = ioremap(r1.start, s1);
 604                 nvram_mult = (s1 + NVRAM_SIZE - 1) / NVRAM_SIZE;
 605                 ppc_md.nvram_read_val   = direct_nvram_read_byte;
 606                 ppc_md.nvram_write_val  = direct_nvram_write_byte;
 607         } else if (nvram_naddrs == 2) {
 608                 nvram_addr = ioremap(r1.start, s1);
 609                 nvram_data = ioremap(r2.start, s2);
 610                 ppc_md.nvram_read_val   = indirect_nvram_read_byte;
 611                 ppc_md.nvram_write_val  = indirect_nvram_write_byte;
 612         } else if (nvram_naddrs == 0 && sys_ctrler == SYS_CTRLER_PMU) {
 613 #ifdef CONFIG_ADB_PMU
 614                 nvram_naddrs = -1;
 615                 ppc_md.nvram_read_val   = pmu_nvram_read_byte;
 616                 ppc_md.nvram_write_val  = pmu_nvram_write_byte;
 617 #endif /* CONFIG_ADB_PMU */
 618         } else {
 619                 printk(KERN_ERR "Incompatible type of NVRAM\n");
 620                 err = -ENXIO;
 621         }
 622 #endif /* CONFIG_PPC32 */
 623 bail:
 624         of_node_put(dp);
 625         if (err == 0)
 626                 lookup_partitions();
 627         return err;
 628 }
 629
 630 int pmac_get_partition(int partition)
 631 {
 632         return nvram_partitions[partition];
 633 }
 634
 635 u8 pmac_xpram_read(int xpaddr)
 636 {
 637         int offset = pmac_get_partition(pmac_nvram_XPRAM);
 638
 639         if (offset < 0 || xpaddr < 0 || xpaddr > 0x100)
 640                 return 0xff;
 641
 642         return ppc_md.nvram_read_val(xpaddr + offset);
 643 }
 644
 645 void pmac_xpram_write(int xpaddr, u8 data)
 646 {
 647         int offset = pmac_get_partition(pmac_nvram_XPRAM);
 648
 649         if (offset < 0 || xpaddr < 0 || xpaddr > 0x100)
 650                 return;
 651
 652         ppc_md.nvram_write_val(xpaddr + offset, data);
 653 }
 654
 655 EXPORT_SYMBOL(pmac_get_partition);
 656 EXPORT_SYMBOL(pmac_xpram_read);
 657 EXPORT_SYMBOL(pmac_xpram_write);