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