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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/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/slab.h>
18 #include <linux/delay.h>
19 #include <linux/errno.h>
20 #include <linux/adb.h>
21 #include <linux/pmu.h>
22 #include <linux/bootmem.h>
23 #include <linux/completion.h>
24 #include <linux/spinlock.h>
25 #include <asm/sections.h>
26 #include <asm/io.h>
27 #include <asm/system.h>
28 #include <asm/prom.h>
29 #include <asm/machdep.h>
30 #include <asm/nvram.h>
31 
32 #include "pmac.h"
33 
34 #define DEBUG
35 
36 #ifdef DEBUG
37 #define DBG(x...) printk(x)
38 #else
39 #define DBG(x...)
40 #endif
41 
42 #define NVRAM_SIZE		0x2000	/* 8kB of non-volatile RAM */
43 
44 #define CORE99_SIGNATURE	0x5a
45 #define CORE99_ADLER_START	0x14
46 
47 /* On Core99, nvram is either a sharp, a micron or an AMD flash */
48 #define SM_FLASH_STATUS_DONE	0x80
49 #define SM_FLASH_STATUS_ERR	0x38
50 
51 #define SM_FLASH_CMD_ERASE_CONFIRM	0xd0
52 #define SM_FLASH_CMD_ERASE_SETUP	0x20
53 #define SM_FLASH_CMD_RESET		0xff
54 #define SM_FLASH_CMD_WRITE_SETUP	0x40
55 #define SM_FLASH_CMD_CLEAR_STATUS	0x50
56 #define SM_FLASH_CMD_READ_STATUS	0x70
57 
58 /* CHRP NVRAM header */
59 struct chrp_header {
60   u8		signature;
61   u8		cksum;
62   u16		len;
63   char          name[12];
64   u8		data[0];
65 };
66 
67 struct core99_header {
68   struct chrp_header	hdr;
69   u32			adler;
70   u32			generation;
71   u32			reserved[2];
72 };
73 
74 /*
75  * Read and write the non-volatile RAM on PowerMacs and CHRP machines.
76  */
77 static int nvram_naddrs;
78 static volatile unsigned char __iomem *nvram_data;
79 static int is_core_99;
80 static int core99_bank = 0;
81 static int nvram_partitions[3];
82 // XXX Turn that into a sem
83 static DEFINE_SPINLOCK(nv_lock);
84 
85 static int (*core99_write_bank)(int bank, u8* datas);
86 static int (*core99_erase_bank)(int bank);
87 
88 static char *nvram_image;
89 
90 
core99_nvram_read_byte(int addr)91 static unsigned char core99_nvram_read_byte(int addr)
92 {
93 	if (nvram_image == NULL)
94 		return 0xff;
95 	return nvram_image[addr];
96 }
97 
core99_nvram_write_byte(int addr,unsigned char val)98 static void core99_nvram_write_byte(int addr, unsigned char val)
99 {
100 	if (nvram_image == NULL)
101 		return;
102 	nvram_image[addr] = val;
103 }
104 
core99_nvram_read(char * buf,size_t count,loff_t * index)105 static ssize_t core99_nvram_read(char *buf, size_t count, loff_t *index)
106 {
107 	int i;
108 
109 	if (nvram_image == NULL)
110 		return -ENODEV;
111 	if (*index > NVRAM_SIZE)
112 		return 0;
113 
114 	i = *index;
115 	if (i + count > NVRAM_SIZE)
116 		count = NVRAM_SIZE - i;
117 
118 	memcpy(buf, &nvram_image[i], count);
119 	*index = i + count;
120 	return count;
121 }
122 
core99_nvram_write(char * buf,size_t count,loff_t * index)123 static ssize_t core99_nvram_write(char *buf, size_t count, loff_t *index)
124 {
125 	int i;
126 
127 	if (nvram_image == NULL)
128 		return -ENODEV;
129 	if (*index > NVRAM_SIZE)
130 		return 0;
131 
132 	i = *index;
133 	if (i + count > NVRAM_SIZE)
134 		count = NVRAM_SIZE - i;
135 
136 	memcpy(&nvram_image[i], buf, count);
137 	*index = i + count;
138 	return count;
139 }
140 
core99_nvram_size(void)141 static ssize_t core99_nvram_size(void)
142 {
143 	if (nvram_image == NULL)
144 		return -ENODEV;
145 	return NVRAM_SIZE;
146 }
147 
148 #ifdef CONFIG_PPC32
149 static volatile unsigned char __iomem *nvram_addr;
150 static int nvram_mult;
151 
direct_nvram_read_byte(int addr)152 static unsigned char direct_nvram_read_byte(int addr)
153 {
154 	return in_8(&nvram_data[(addr & (NVRAM_SIZE - 1)) * nvram_mult]);
155 }
156 
direct_nvram_write_byte(int addr,unsigned char val)157 static void direct_nvram_write_byte(int addr, unsigned char val)
158 {
159 	out_8(&nvram_data[(addr & (NVRAM_SIZE - 1)) * nvram_mult], val);
160 }
161 
162 
indirect_nvram_read_byte(int addr)163 static unsigned char indirect_nvram_read_byte(int addr)
164 {
165 	unsigned char val;
166 	unsigned long flags;
167 
168 	spin_lock_irqsave(&nv_lock, flags);
169 	out_8(nvram_addr, addr >> 5);
170 	val = in_8(&nvram_data[(addr & 0x1f) << 4]);
171 	spin_unlock_irqrestore(&nv_lock, flags);
172 
173 	return val;
174 }
175 
indirect_nvram_write_byte(int addr,unsigned char val)176 static void indirect_nvram_write_byte(int addr, unsigned char val)
177 {
178 	unsigned long flags;
179 
180 	spin_lock_irqsave(&nv_lock, flags);
181 	out_8(nvram_addr, addr >> 5);
182 	out_8(&nvram_data[(addr & 0x1f) << 4], val);
183 	spin_unlock_irqrestore(&nv_lock, flags);
184 }
185 
186 
187 #ifdef CONFIG_ADB_PMU
188 
pmu_nvram_complete(struct adb_request * req)189 static void pmu_nvram_complete(struct adb_request *req)
190 {
191 	if (req->arg)
192 		complete((struct completion *)req->arg);
193 }
194 
pmu_nvram_read_byte(int addr)195 static unsigned char pmu_nvram_read_byte(int addr)
196 {
197 	struct adb_request req;
198 	DECLARE_COMPLETION_ONSTACK(req_complete);
199 
200 	req.arg = system_state == SYSTEM_RUNNING ? &req_complete : NULL;
201 	if (pmu_request(&req, pmu_nvram_complete, 3, PMU_READ_NVRAM,
202 			(addr >> 8) & 0xff, addr & 0xff))
203 		return 0xff;
204 	if (system_state == SYSTEM_RUNNING)
205 		wait_for_completion(&req_complete);
206 	while (!req.complete)
207 		pmu_poll();
208 	return req.reply[0];
209 }
210 
pmu_nvram_write_byte(int addr,unsigned char val)211 static void pmu_nvram_write_byte(int addr, unsigned char val)
212 {
213 	struct adb_request req;
214 	DECLARE_COMPLETION_ONSTACK(req_complete);
215 
216 	req.arg = system_state == SYSTEM_RUNNING ? &req_complete : NULL;
217 	if (pmu_request(&req, pmu_nvram_complete, 4, PMU_WRITE_NVRAM,
218 			(addr >> 8) & 0xff, addr & 0xff, val))
219 		return;
220 	if (system_state == SYSTEM_RUNNING)
221 		wait_for_completion(&req_complete);
222 	while (!req.complete)
223 		pmu_poll();
224 }
225 
226 #endif /* CONFIG_ADB_PMU */
227 #endif /* CONFIG_PPC32 */
228 
chrp_checksum(struct chrp_header * hdr)229 static u8 chrp_checksum(struct chrp_header* hdr)
230 {
231 	u8 *ptr;
232 	u16 sum = hdr->signature;
233 	for (ptr = (u8 *)&hdr->len; ptr < hdr->data; ptr++)
234 		sum += *ptr;
235 	while (sum > 0xFF)
236 		sum = (sum & 0xFF) + (sum>>8);
237 	return sum;
238 }
239 
core99_calc_adler(u8 * buffer)240 static u32 core99_calc_adler(u8 *buffer)
241 {
242 	int cnt;
243 	u32 low, high;
244 
245    	buffer += CORE99_ADLER_START;
246 	low = 1;
247 	high = 0;
248 	for (cnt=0; cnt<(NVRAM_SIZE-CORE99_ADLER_START); cnt++) {
249 		if ((cnt % 5000) == 0) {
250 			high  %= 65521UL;
251 			high %= 65521UL;
252 		}
253 		low += buffer[cnt];
254 		high += low;
255 	}
256 	low  %= 65521UL;
257 	high %= 65521UL;
258 
259 	return (high << 16) | low;
260 }
261 
core99_check(u8 * datas)262 static u32 core99_check(u8* datas)
263 {
264 	struct core99_header* hdr99 = (struct core99_header*)datas;
265 
266 	if (hdr99->hdr.signature != CORE99_SIGNATURE) {
267 		DBG("Invalid signature\n");
268 		return 0;
269 	}
270 	if (hdr99->hdr.cksum != chrp_checksum(&hdr99->hdr)) {
271 		DBG("Invalid checksum\n");
272 		return 0;
273 	}
274 	if (hdr99->adler != core99_calc_adler(datas)) {
275 		DBG("Invalid adler\n");
276 		return 0;
277 	}
278 	return hdr99->generation;
279 }
280 
sm_erase_bank(int bank)281 static int sm_erase_bank(int bank)
282 {
283 	int stat, i;
284 	unsigned long timeout;
285 
286 	u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
287 
288        	DBG("nvram: Sharp/Micron Erasing bank %d...\n", bank);
289 
290 	out_8(base, SM_FLASH_CMD_ERASE_SETUP);
291 	out_8(base, SM_FLASH_CMD_ERASE_CONFIRM);
292 	timeout = 0;
293 	do {
294 		if (++timeout > 1000000) {
295 			printk(KERN_ERR "nvram: Sharp/Micron flash erase timeout !\n");
296 			break;
297 		}
298 		out_8(base, SM_FLASH_CMD_READ_STATUS);
299 		stat = in_8(base);
300 	} while (!(stat & SM_FLASH_STATUS_DONE));
301 
302 	out_8(base, SM_FLASH_CMD_CLEAR_STATUS);
303 	out_8(base, SM_FLASH_CMD_RESET);
304 
305 	for (i=0; i<NVRAM_SIZE; i++)
306 		if (base[i] != 0xff) {
307 			printk(KERN_ERR "nvram: Sharp/Micron flash erase failed !\n");
308 			return -ENXIO;
309 		}
310 	return 0;
311 }
312 
sm_write_bank(int bank,u8 * datas)313 static int sm_write_bank(int bank, u8* datas)
314 {
315 	int i, stat = 0;
316 	unsigned long timeout;
317 
318 	u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
319 
320        	DBG("nvram: Sharp/Micron Writing bank %d...\n", bank);
321 
322 	for (i=0; i<NVRAM_SIZE; i++) {
323 		out_8(base+i, SM_FLASH_CMD_WRITE_SETUP);
324 		udelay(1);
325 		out_8(base+i, datas[i]);
326 		timeout = 0;
327 		do {
328 			if (++timeout > 1000000) {
329 				printk(KERN_ERR "nvram: Sharp/Micron flash write timeout !\n");
330 				break;
331 			}
332 			out_8(base, SM_FLASH_CMD_READ_STATUS);
333 			stat = in_8(base);
334 		} while (!(stat & SM_FLASH_STATUS_DONE));
335 		if (!(stat & SM_FLASH_STATUS_DONE))
336 			break;
337 	}
338 	out_8(base, SM_FLASH_CMD_CLEAR_STATUS);
339 	out_8(base, SM_FLASH_CMD_RESET);
340 	for (i=0; i<NVRAM_SIZE; i++)
341 		if (base[i] != datas[i]) {
342 			printk(KERN_ERR "nvram: Sharp/Micron flash write failed !\n");
343 			return -ENXIO;
344 		}
345 	return 0;
346 }
347 
amd_erase_bank(int bank)348 static int amd_erase_bank(int bank)
349 {
350 	int i, stat = 0;
351 	unsigned long timeout;
352 
353 	u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
354 
355        	DBG("nvram: AMD Erasing bank %d...\n", bank);
356 
357 	/* Unlock 1 */
358 	out_8(base+0x555, 0xaa);
359 	udelay(1);
360 	/* Unlock 2 */
361 	out_8(base+0x2aa, 0x55);
362 	udelay(1);
363 
364 	/* Sector-Erase */
365 	out_8(base+0x555, 0x80);
366 	udelay(1);
367 	out_8(base+0x555, 0xaa);
368 	udelay(1);
369 	out_8(base+0x2aa, 0x55);
370 	udelay(1);
371 	out_8(base, 0x30);
372 	udelay(1);
373 
374 	timeout = 0;
375 	do {
376 		if (++timeout > 1000000) {
377 			printk(KERN_ERR "nvram: AMD flash erase timeout !\n");
378 			break;
379 		}
380 		stat = in_8(base) ^ in_8(base);
381 	} while (stat != 0);
382 
383 	/* Reset */
384 	out_8(base, 0xf0);
385 	udelay(1);
386 
387 	for (i=0; i<NVRAM_SIZE; i++)
388 		if (base[i] != 0xff) {
389 			printk(KERN_ERR "nvram: AMD flash erase failed !\n");
390 			return -ENXIO;
391 		}
392 	return 0;
393 }
394 
amd_write_bank(int bank,u8 * datas)395 static int amd_write_bank(int bank, u8* datas)
396 {
397 	int i, stat = 0;
398 	unsigned long timeout;
399 
400 	u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
401 
402        	DBG("nvram: AMD Writing bank %d...\n", bank);
403 
404 	for (i=0; i<NVRAM_SIZE; i++) {
405 		/* Unlock 1 */
406 		out_8(base+0x555, 0xaa);
407 		udelay(1);
408 		/* Unlock 2 */
409 		out_8(base+0x2aa, 0x55);
410 		udelay(1);
411 
412 		/* Write single word */
413 		out_8(base+0x555, 0xa0);
414 		udelay(1);
415 		out_8(base+i, datas[i]);
416 
417 		timeout = 0;
418 		do {
419 			if (++timeout > 1000000) {
420 				printk(KERN_ERR "nvram: AMD flash write timeout !\n");
421 				break;
422 			}
423 			stat = in_8(base) ^ in_8(base);
424 		} while (stat != 0);
425 		if (stat != 0)
426 			break;
427 	}
428 
429 	/* Reset */
430 	out_8(base, 0xf0);
431 	udelay(1);
432 
433 	for (i=0; i<NVRAM_SIZE; i++)
434 		if (base[i] != datas[i]) {
435 			printk(KERN_ERR "nvram: AMD flash write failed !\n");
436 			return -ENXIO;
437 		}
438 	return 0;
439 }
440 
lookup_partitions(void)441 static void __init lookup_partitions(void)
442 {
443 	u8 buffer[17];
444 	int i, offset;
445 	struct chrp_header* hdr;
446 
447 	if (pmac_newworld) {
448 		nvram_partitions[pmac_nvram_OF] = -1;
449 		nvram_partitions[pmac_nvram_XPRAM] = -1;
450 		nvram_partitions[pmac_nvram_NR] = -1;
451 		hdr = (struct chrp_header *)buffer;
452 
453 		offset = 0;
454 		buffer[16] = 0;
455 		do {
456 			for (i=0;i<16;i++)
457 				buffer[i] = ppc_md.nvram_read_val(offset+i);
458 			if (!strcmp(hdr->name, "common"))
459 				nvram_partitions[pmac_nvram_OF] = offset + 0x10;
460 			if (!strcmp(hdr->name, "APL,MacOS75")) {
461 				nvram_partitions[pmac_nvram_XPRAM] = offset + 0x10;
462 				nvram_partitions[pmac_nvram_NR] = offset + 0x110;
463 			}
464 			offset += (hdr->len * 0x10);
465 		} while(offset < NVRAM_SIZE);
466 	} else {
467 		nvram_partitions[pmac_nvram_OF] = 0x1800;
468 		nvram_partitions[pmac_nvram_XPRAM] = 0x1300;
469 		nvram_partitions[pmac_nvram_NR] = 0x1400;
470 	}
471 	DBG("nvram: OF partition at 0x%x\n", nvram_partitions[pmac_nvram_OF]);
472 	DBG("nvram: XP partition at 0x%x\n", nvram_partitions[pmac_nvram_XPRAM]);
473 	DBG("nvram: NR partition at 0x%x\n", nvram_partitions[pmac_nvram_NR]);
474 }
475 
core99_nvram_sync(void)476 static void core99_nvram_sync(void)
477 {
478 	struct core99_header* hdr99;
479 	unsigned long flags;
480 
481 	if (!is_core_99 || !nvram_data || !nvram_image)
482 		return;
483 
484 	spin_lock_irqsave(&nv_lock, flags);
485 	if (!memcmp(nvram_image, (u8*)nvram_data + core99_bank*NVRAM_SIZE,
486 		NVRAM_SIZE))
487 		goto bail;
488 
489 	DBG("Updating nvram...\n");
490 
491 	hdr99 = (struct core99_header*)nvram_image;
492 	hdr99->generation++;
493 	hdr99->hdr.signature = CORE99_SIGNATURE;
494 	hdr99->hdr.cksum = chrp_checksum(&hdr99->hdr);
495 	hdr99->adler = core99_calc_adler(nvram_image);
496 	core99_bank = core99_bank ? 0 : 1;
497 	if (core99_erase_bank)
498 		if (core99_erase_bank(core99_bank)) {
499 			printk("nvram: Error erasing bank %d\n", core99_bank);
500 			goto bail;
501 		}
502 	if (core99_write_bank)
503 		if (core99_write_bank(core99_bank, nvram_image))
504 			printk("nvram: Error writing bank %d\n", core99_bank);
505  bail:
506 	spin_unlock_irqrestore(&nv_lock, flags);
507 
508 #ifdef DEBUG
509        	mdelay(2000);
510 #endif
511 }
512 
core99_nvram_setup(struct device_node * dp,unsigned long addr)513 static int __init core99_nvram_setup(struct device_node *dp, unsigned long addr)
514 {
515 	int i;
516 	u32 gen_bank0, gen_bank1;
517 
518 	if (nvram_naddrs < 1) {
519 		printk(KERN_ERR "nvram: no address\n");
520 		return -EINVAL;
521 	}
522 	nvram_image = alloc_bootmem(NVRAM_SIZE);
523 	if (nvram_image == NULL) {
524 		printk(KERN_ERR "nvram: can't allocate ram image\n");
525 		return -ENOMEM;
526 	}
527 	nvram_data = ioremap(addr, NVRAM_SIZE*2);
528 	nvram_naddrs = 1; /* Make sure we get the correct case */
529 
530 	DBG("nvram: Checking bank 0...\n");
531 
532 	gen_bank0 = core99_check((u8 *)nvram_data);
533 	gen_bank1 = core99_check((u8 *)nvram_data + NVRAM_SIZE);
534 	core99_bank = (gen_bank0 < gen_bank1) ? 1 : 0;
535 
536 	DBG("nvram: gen0=%d, gen1=%d\n", gen_bank0, gen_bank1);
537 	DBG("nvram: Active bank is: %d\n", core99_bank);
538 
539 	for (i=0; i<NVRAM_SIZE; i++)
540 		nvram_image[i] = nvram_data[i + core99_bank*NVRAM_SIZE];
541 
542 	ppc_md.nvram_read_val	= core99_nvram_read_byte;
543 	ppc_md.nvram_write_val	= core99_nvram_write_byte;
544 	ppc_md.nvram_read	= core99_nvram_read;
545 	ppc_md.nvram_write	= core99_nvram_write;
546 	ppc_md.nvram_size	= core99_nvram_size;
547 	ppc_md.nvram_sync	= core99_nvram_sync;
548 	ppc_md.machine_shutdown	= core99_nvram_sync;
549 	/*
550 	 * Maybe we could be smarter here though making an exclusive list
551 	 * of known flash chips is a bit nasty as older OF didn't provide us
552 	 * with a useful "compatible" entry. A solution would be to really
553 	 * identify the chip using flash id commands and base ourselves on
554 	 * a list of known chips IDs
555 	 */
556 	if (of_device_is_compatible(dp, "amd-0137")) {
557 		core99_erase_bank = amd_erase_bank;
558 		core99_write_bank = amd_write_bank;
559 	} else {
560 		core99_erase_bank = sm_erase_bank;
561 		core99_write_bank = sm_write_bank;
562 	}
563 	return 0;
564 }
565 
pmac_nvram_init(void)566 int __init pmac_nvram_init(void)
567 {
568 	struct device_node *dp;
569 	struct resource r1, r2;
570 	unsigned int s1 = 0, s2 = 0;
571 	int err = 0;
572 
573 	nvram_naddrs = 0;
574 
575 	dp = of_find_node_by_name(NULL, "nvram");
576 	if (dp == NULL) {
577 		printk(KERN_ERR "Can't find NVRAM device\n");
578 		return -ENODEV;
579 	}
580 
581 	/* Try to obtain an address */
582 	if (of_address_to_resource(dp, 0, &r1) == 0) {
583 		nvram_naddrs = 1;
584 		s1 = (r1.end - r1.start) + 1;
585 		if (of_address_to_resource(dp, 1, &r2) == 0) {
586 			nvram_naddrs = 2;
587 			s2 = (r2.end - r2.start) + 1;
588 		}
589 	}
590 
591 	is_core_99 = of_device_is_compatible(dp, "nvram,flash");
592 	if (is_core_99) {
593 		err = core99_nvram_setup(dp, r1.start);
594 		goto bail;
595 	}
596 
597 #ifdef CONFIG_PPC32
598 	if (machine_is(chrp) && nvram_naddrs == 1) {
599 		nvram_data = ioremap(r1.start, s1);
600 		nvram_mult = 1;
601 		ppc_md.nvram_read_val	= direct_nvram_read_byte;
602 		ppc_md.nvram_write_val	= direct_nvram_write_byte;
603 	} else if (nvram_naddrs == 1) {
604 		nvram_data = ioremap(r1.start, s1);
605 		nvram_mult = (s1 + NVRAM_SIZE - 1) / NVRAM_SIZE;
606 		ppc_md.nvram_read_val	= direct_nvram_read_byte;
607 		ppc_md.nvram_write_val	= direct_nvram_write_byte;
608 	} else if (nvram_naddrs == 2) {
609 		nvram_addr = ioremap(r1.start, s1);
610 		nvram_data = ioremap(r2.start, s2);
611 		ppc_md.nvram_read_val	= indirect_nvram_read_byte;
612 		ppc_md.nvram_write_val	= indirect_nvram_write_byte;
613 	} else if (nvram_naddrs == 0 && sys_ctrler == SYS_CTRLER_PMU) {
614 #ifdef CONFIG_ADB_PMU
615 		nvram_naddrs = -1;
616 		ppc_md.nvram_read_val	= pmu_nvram_read_byte;
617 		ppc_md.nvram_write_val	= pmu_nvram_write_byte;
618 #endif /* CONFIG_ADB_PMU */
619 	} else {
620 		printk(KERN_ERR "Incompatible type of NVRAM\n");
621 		err = -ENXIO;
622 	}
623 #endif /* CONFIG_PPC32 */
624 bail:
625 	of_node_put(dp);
626 	if (err == 0)
627 		lookup_partitions();
628 	return err;
629 }
630 
pmac_get_partition(int partition)631 int pmac_get_partition(int partition)
632 {
633 	return nvram_partitions[partition];
634 }
635 
pmac_xpram_read(int xpaddr)636 u8 pmac_xpram_read(int xpaddr)
637 {
638 	int offset = pmac_get_partition(pmac_nvram_XPRAM);
639 
640 	if (offset < 0 || xpaddr < 0 || xpaddr > 0x100)
641 		return 0xff;
642 
643 	return ppc_md.nvram_read_val(xpaddr + offset);
644 }
645 
pmac_xpram_write(int xpaddr,u8 data)646 void pmac_xpram_write(int xpaddr, u8 data)
647 {
648 	int offset = pmac_get_partition(pmac_nvram_XPRAM);
649 
650 	if (offset < 0 || xpaddr < 0 || xpaddr > 0x100)
651 		return;
652 
653 	ppc_md.nvram_write_val(xpaddr + offset, data);
654 }
655 
656 EXPORT_SYMBOL(pmac_get_partition);
657 EXPORT_SYMBOL(pmac_xpram_read);
658 EXPORT_SYMBOL(pmac_xpram_write);
659