1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Copyright (C) 2002 Benjamin Herrenschmidt (benh@kernel.crashing.org)
4  *
5  *  Todo: - add support for the OF persistent properties
6  */
7 #include <linux/export.h>
8 #include <linux/kernel.h>
9 #include <linux/stddef.h>
10 #include <linux/string.h>
11 #include <linux/nvram.h>
12 #include <linux/init.h>
13 #include <linux/delay.h>
14 #include <linux/errno.h>
15 #include <linux/adb.h>
16 #include <linux/pmu.h>
17 #include <linux/memblock.h>
18 #include <linux/completion.h>
19 #include <linux/spinlock.h>
20 #include <linux/of_address.h>
21 #include <asm/sections.h>
22 #include <asm/io.h>
23 #include <asm/machdep.h>
24 #include <asm/nvram.h>
25 
26 #include "pmac.h"
27 
28 #define DEBUG
29 
30 #ifdef DEBUG
31 #define DBG(x...) printk(x)
32 #else
33 #define DBG(x...)
34 #endif
35 
36 #define NVRAM_SIZE		0x2000	/* 8kB of non-volatile RAM */
37 
38 #define CORE99_SIGNATURE	0x5a
39 #define CORE99_ADLER_START	0x14
40 
41 /* On Core99, nvram is either a sharp, a micron or an AMD flash */
42 #define SM_FLASH_STATUS_DONE	0x80
43 #define SM_FLASH_STATUS_ERR	0x38
44 
45 #define SM_FLASH_CMD_ERASE_CONFIRM	0xd0
46 #define SM_FLASH_CMD_ERASE_SETUP	0x20
47 #define SM_FLASH_CMD_RESET		0xff
48 #define SM_FLASH_CMD_WRITE_SETUP	0x40
49 #define SM_FLASH_CMD_CLEAR_STATUS	0x50
50 #define SM_FLASH_CMD_READ_STATUS	0x70
51 
52 /* CHRP NVRAM header */
53 struct chrp_header {
54   u8		signature;
55   u8		cksum;
56   u16		len;
57   char          name[12];
58   u8		data[];
59 };
60 
61 struct core99_header {
62   struct chrp_header	hdr;
63   u32			adler;
64   u32			generation;
65   u32			reserved[2];
66 };
67 
68 /*
69  * Read and write the non-volatile RAM on PowerMacs and CHRP machines.
70  */
71 static int nvram_naddrs;
72 static volatile unsigned char __iomem *nvram_data;
73 static int is_core_99;
74 static int core99_bank;
75 static int nvram_partitions[3];
76 // XXX Turn that into a sem
77 static DEFINE_RAW_SPINLOCK(nv_lock);
78 
79 static int (*core99_write_bank)(int bank, u8* datas);
80 static int (*core99_erase_bank)(int bank);
81 
82 static char *nvram_image;
83 
84 
core99_nvram_read_byte(int addr)85 static unsigned char core99_nvram_read_byte(int addr)
86 {
87 	if (nvram_image == NULL)
88 		return 0xff;
89 	return nvram_image[addr];
90 }
91 
core99_nvram_write_byte(int addr,unsigned char val)92 static void core99_nvram_write_byte(int addr, unsigned char val)
93 {
94 	if (nvram_image == NULL)
95 		return;
96 	nvram_image[addr] = val;
97 }
98 
core99_nvram_read(char * buf,size_t count,loff_t * index)99 static ssize_t core99_nvram_read(char *buf, size_t count, loff_t *index)
100 {
101 	int i;
102 
103 	if (nvram_image == NULL)
104 		return -ENODEV;
105 	if (*index > NVRAM_SIZE)
106 		return 0;
107 
108 	i = *index;
109 	if (i + count > NVRAM_SIZE)
110 		count = NVRAM_SIZE - i;
111 
112 	memcpy(buf, &nvram_image[i], count);
113 	*index = i + count;
114 	return count;
115 }
116 
core99_nvram_write(char * buf,size_t count,loff_t * index)117 static ssize_t core99_nvram_write(char *buf, size_t count, loff_t *index)
118 {
119 	int i;
120 
121 	if (nvram_image == NULL)
122 		return -ENODEV;
123 	if (*index > NVRAM_SIZE)
124 		return 0;
125 
126 	i = *index;
127 	if (i + count > NVRAM_SIZE)
128 		count = NVRAM_SIZE - i;
129 
130 	memcpy(&nvram_image[i], buf, count);
131 	*index = i + count;
132 	return count;
133 }
134 
core99_nvram_size(void)135 static ssize_t core99_nvram_size(void)
136 {
137 	if (nvram_image == NULL)
138 		return -ENODEV;
139 	return NVRAM_SIZE;
140 }
141 
142 #ifdef CONFIG_PPC32
143 static volatile unsigned char __iomem *nvram_addr;
144 static int nvram_mult;
145 
ppc32_nvram_size(void)146 static ssize_t ppc32_nvram_size(void)
147 {
148 	return NVRAM_SIZE;
149 }
150 
direct_nvram_read_byte(int addr)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 
direct_nvram_write_byte(int addr,unsigned char val)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 
indirect_nvram_read_byte(int addr)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 
indirect_nvram_write_byte(int addr,unsigned char val)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 
pmu_nvram_complete(struct adb_request * req)188 static void pmu_nvram_complete(struct adb_request *req)
189 {
190 	if (req->arg)
191 		complete((struct completion *)req->arg);
192 }
193 
pmu_nvram_read_byte(int addr)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 
pmu_nvram_write_byte(int addr,unsigned char val)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 
chrp_checksum(struct chrp_header * hdr)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 
core99_calc_adler(u8 * buffer)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 
core99_check(u8 * datas)261 static u32 __init 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 
sm_erase_bank(int bank)280 static int sm_erase_bank(int bank)
281 {
282 	int stat;
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 	if (memchr_inv(base, 0xff, NVRAM_SIZE)) {
305 		printk(KERN_ERR "nvram: Sharp/Micron flash erase failed !\n");
306 		return -ENXIO;
307 	}
308 	return 0;
309 }
310 
sm_write_bank(int bank,u8 * datas)311 static int sm_write_bank(int bank, u8* datas)
312 {
313 	int i, stat = 0;
314 	unsigned long timeout;
315 
316 	u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
317 
318        	DBG("nvram: Sharp/Micron Writing bank %d...\n", bank);
319 
320 	for (i=0; i<NVRAM_SIZE; i++) {
321 		out_8(base+i, SM_FLASH_CMD_WRITE_SETUP);
322 		udelay(1);
323 		out_8(base+i, datas[i]);
324 		timeout = 0;
325 		do {
326 			if (++timeout > 1000000) {
327 				printk(KERN_ERR "nvram: Sharp/Micron flash write timeout !\n");
328 				break;
329 			}
330 			out_8(base, SM_FLASH_CMD_READ_STATUS);
331 			stat = in_8(base);
332 		} while (!(stat & SM_FLASH_STATUS_DONE));
333 		if (!(stat & SM_FLASH_STATUS_DONE))
334 			break;
335 	}
336 	out_8(base, SM_FLASH_CMD_CLEAR_STATUS);
337 	out_8(base, SM_FLASH_CMD_RESET);
338 	if (memcmp(base, datas, NVRAM_SIZE)) {
339 		printk(KERN_ERR "nvram: Sharp/Micron flash write failed !\n");
340 		return -ENXIO;
341 	}
342 	return 0;
343 }
344 
amd_erase_bank(int bank)345 static int amd_erase_bank(int bank)
346 {
347 	int stat = 0;
348 	unsigned long timeout;
349 
350 	u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
351 
352        	DBG("nvram: AMD Erasing bank %d...\n", bank);
353 
354 	/* Unlock 1 */
355 	out_8(base+0x555, 0xaa);
356 	udelay(1);
357 	/* Unlock 2 */
358 	out_8(base+0x2aa, 0x55);
359 	udelay(1);
360 
361 	/* Sector-Erase */
362 	out_8(base+0x555, 0x80);
363 	udelay(1);
364 	out_8(base+0x555, 0xaa);
365 	udelay(1);
366 	out_8(base+0x2aa, 0x55);
367 	udelay(1);
368 	out_8(base, 0x30);
369 	udelay(1);
370 
371 	timeout = 0;
372 	do {
373 		if (++timeout > 1000000) {
374 			printk(KERN_ERR "nvram: AMD flash erase timeout !\n");
375 			break;
376 		}
377 		stat = in_8(base) ^ in_8(base);
378 	} while (stat != 0);
379 
380 	/* Reset */
381 	out_8(base, 0xf0);
382 	udelay(1);
383 
384 	if (memchr_inv(base, 0xff, NVRAM_SIZE)) {
385 		printk(KERN_ERR "nvram: AMD flash erase failed !\n");
386 		return -ENXIO;
387 	}
388 	return 0;
389 }
390 
amd_write_bank(int bank,u8 * datas)391 static int amd_write_bank(int bank, u8* datas)
392 {
393 	int i, stat = 0;
394 	unsigned long timeout;
395 
396 	u8 __iomem *base = (u8 __iomem *)nvram_data + core99_bank*NVRAM_SIZE;
397 
398        	DBG("nvram: AMD Writing bank %d...\n", bank);
399 
400 	for (i=0; i<NVRAM_SIZE; i++) {
401 		/* Unlock 1 */
402 		out_8(base+0x555, 0xaa);
403 		udelay(1);
404 		/* Unlock 2 */
405 		out_8(base+0x2aa, 0x55);
406 		udelay(1);
407 
408 		/* Write single word */
409 		out_8(base+0x555, 0xa0);
410 		udelay(1);
411 		out_8(base+i, datas[i]);
412 
413 		timeout = 0;
414 		do {
415 			if (++timeout > 1000000) {
416 				printk(KERN_ERR "nvram: AMD flash write timeout !\n");
417 				break;
418 			}
419 			stat = in_8(base) ^ in_8(base);
420 		} while (stat != 0);
421 		if (stat != 0)
422 			break;
423 	}
424 
425 	/* Reset */
426 	out_8(base, 0xf0);
427 	udelay(1);
428 
429 	if (memcmp(base, datas, NVRAM_SIZE)) {
430 		printk(KERN_ERR "nvram: AMD flash write failed !\n");
431 		return -ENXIO;
432 	}
433 	return 0;
434 }
435 
lookup_partitions(void)436 static void __init lookup_partitions(void)
437 {
438 	u8 buffer[17];
439 	int i, offset;
440 	struct chrp_header* hdr;
441 
442 	if (pmac_newworld) {
443 		nvram_partitions[pmac_nvram_OF] = -1;
444 		nvram_partitions[pmac_nvram_XPRAM] = -1;
445 		nvram_partitions[pmac_nvram_NR] = -1;
446 		hdr = (struct chrp_header *)buffer;
447 
448 		offset = 0;
449 		buffer[16] = 0;
450 		do {
451 			for (i=0;i<16;i++)
452 				buffer[i] = ppc_md.nvram_read_val(offset+i);
453 			if (!strcmp(hdr->name, "common"))
454 				nvram_partitions[pmac_nvram_OF] = offset + 0x10;
455 			if (!strcmp(hdr->name, "APL,MacOS75")) {
456 				nvram_partitions[pmac_nvram_XPRAM] = offset + 0x10;
457 				nvram_partitions[pmac_nvram_NR] = offset + 0x110;
458 			}
459 			offset += (hdr->len * 0x10);
460 		} while(offset < NVRAM_SIZE);
461 	} else {
462 		nvram_partitions[pmac_nvram_OF] = 0x1800;
463 		nvram_partitions[pmac_nvram_XPRAM] = 0x1300;
464 		nvram_partitions[pmac_nvram_NR] = 0x1400;
465 	}
466 	DBG("nvram: OF partition at 0x%x\n", nvram_partitions[pmac_nvram_OF]);
467 	DBG("nvram: XP partition at 0x%x\n", nvram_partitions[pmac_nvram_XPRAM]);
468 	DBG("nvram: NR partition at 0x%x\n", nvram_partitions[pmac_nvram_NR]);
469 }
470 
core99_nvram_sync(void)471 static void core99_nvram_sync(void)
472 {
473 	struct core99_header* hdr99;
474 	unsigned long flags;
475 
476 	if (!is_core_99 || !nvram_data || !nvram_image)
477 		return;
478 
479 	raw_spin_lock_irqsave(&nv_lock, flags);
480 	if (!memcmp(nvram_image, (u8*)nvram_data + core99_bank*NVRAM_SIZE,
481 		NVRAM_SIZE))
482 		goto bail;
483 
484 	DBG("Updating nvram...\n");
485 
486 	hdr99 = (struct core99_header*)nvram_image;
487 	hdr99->generation++;
488 	hdr99->hdr.signature = CORE99_SIGNATURE;
489 	hdr99->hdr.cksum = chrp_checksum(&hdr99->hdr);
490 	hdr99->adler = core99_calc_adler(nvram_image);
491 	core99_bank = core99_bank ? 0 : 1;
492 	if (core99_erase_bank)
493 		if (core99_erase_bank(core99_bank)) {
494 			printk("nvram: Error erasing bank %d\n", core99_bank);
495 			goto bail;
496 		}
497 	if (core99_write_bank)
498 		if (core99_write_bank(core99_bank, nvram_image))
499 			printk("nvram: Error writing bank %d\n", core99_bank);
500  bail:
501 	raw_spin_unlock_irqrestore(&nv_lock, flags);
502 
503 #ifdef DEBUG
504        	mdelay(2000);
505 #endif
506 }
507 
core99_nvram_setup(struct device_node * dp,unsigned long addr)508 static int __init core99_nvram_setup(struct device_node *dp, unsigned long addr)
509 {
510 	int i;
511 	u32 gen_bank0, gen_bank1;
512 
513 	if (nvram_naddrs < 1) {
514 		printk(KERN_ERR "nvram: no address\n");
515 		return -EINVAL;
516 	}
517 	nvram_image = memblock_alloc(NVRAM_SIZE, SMP_CACHE_BYTES);
518 	if (!nvram_image)
519 		panic("%s: Failed to allocate %u bytes\n", __func__,
520 		      NVRAM_SIZE);
521 	nvram_data = ioremap(addr, NVRAM_SIZE*2);
522 	nvram_naddrs = 1; /* Make sure we get the correct case */
523 
524 	DBG("nvram: Checking bank 0...\n");
525 
526 	gen_bank0 = core99_check((u8 *)nvram_data);
527 	gen_bank1 = core99_check((u8 *)nvram_data + NVRAM_SIZE);
528 	core99_bank = (gen_bank0 < gen_bank1) ? 1 : 0;
529 
530 	DBG("nvram: gen0=%d, gen1=%d\n", gen_bank0, gen_bank1);
531 	DBG("nvram: Active bank is: %d\n", core99_bank);
532 
533 	for (i=0; i<NVRAM_SIZE; i++)
534 		nvram_image[i] = nvram_data[i + core99_bank*NVRAM_SIZE];
535 
536 	ppc_md.nvram_read_val	= core99_nvram_read_byte;
537 	ppc_md.nvram_write_val	= core99_nvram_write_byte;
538 	ppc_md.nvram_read	= core99_nvram_read;
539 	ppc_md.nvram_write	= core99_nvram_write;
540 	ppc_md.nvram_size	= core99_nvram_size;
541 	ppc_md.nvram_sync	= core99_nvram_sync;
542 	ppc_md.machine_shutdown	= core99_nvram_sync;
543 	/*
544 	 * Maybe we could be smarter here though making an exclusive list
545 	 * of known flash chips is a bit nasty as older OF didn't provide us
546 	 * with a useful "compatible" entry. A solution would be to really
547 	 * identify the chip using flash id commands and base ourselves on
548 	 * a list of known chips IDs
549 	 */
550 	if (of_device_is_compatible(dp, "amd-0137")) {
551 		core99_erase_bank = amd_erase_bank;
552 		core99_write_bank = amd_write_bank;
553 	} else {
554 		core99_erase_bank = sm_erase_bank;
555 		core99_write_bank = sm_write_bank;
556 	}
557 	return 0;
558 }
559 
pmac_nvram_init(void)560 int __init pmac_nvram_init(void)
561 {
562 	struct device_node *dp;
563 	struct resource r1, r2;
564 	unsigned int s1 = 0, s2 = 0;
565 	int err = 0;
566 
567 	nvram_naddrs = 0;
568 
569 	dp = of_find_node_by_name(NULL, "nvram");
570 	if (dp == NULL) {
571 		printk(KERN_ERR "Can't find NVRAM device\n");
572 		return -ENODEV;
573 	}
574 
575 	/* Try to obtain an address */
576 	if (of_address_to_resource(dp, 0, &r1) == 0) {
577 		nvram_naddrs = 1;
578 		s1 = resource_size(&r1);
579 		if (of_address_to_resource(dp, 1, &r2) == 0) {
580 			nvram_naddrs = 2;
581 			s2 = resource_size(&r2);
582 		}
583 	}
584 
585 	is_core_99 = of_device_is_compatible(dp, "nvram,flash");
586 	if (is_core_99) {
587 		err = core99_nvram_setup(dp, r1.start);
588 		goto bail;
589 	}
590 
591 #ifdef CONFIG_PPC32
592 	if (machine_is(chrp) && nvram_naddrs == 1) {
593 		nvram_data = ioremap(r1.start, s1);
594 		nvram_mult = 1;
595 		ppc_md.nvram_read_val	= direct_nvram_read_byte;
596 		ppc_md.nvram_write_val	= direct_nvram_write_byte;
597 		ppc_md.nvram_size	= ppc32_nvram_size;
598 	} else if (nvram_naddrs == 1) {
599 		nvram_data = ioremap(r1.start, s1);
600 		nvram_mult = (s1 + NVRAM_SIZE - 1) / NVRAM_SIZE;
601 		ppc_md.nvram_read_val	= direct_nvram_read_byte;
602 		ppc_md.nvram_write_val	= direct_nvram_write_byte;
603 		ppc_md.nvram_size	= ppc32_nvram_size;
604 	} else if (nvram_naddrs == 2) {
605 		nvram_addr = ioremap(r1.start, s1);
606 		nvram_data = ioremap(r2.start, s2);
607 		ppc_md.nvram_read_val	= indirect_nvram_read_byte;
608 		ppc_md.nvram_write_val	= indirect_nvram_write_byte;
609 		ppc_md.nvram_size	= ppc32_nvram_size;
610 	} else if (nvram_naddrs == 0 && sys_ctrler == SYS_CTRLER_PMU) {
611 #ifdef CONFIG_ADB_PMU
612 		nvram_naddrs = -1;
613 		ppc_md.nvram_read_val	= pmu_nvram_read_byte;
614 		ppc_md.nvram_write_val	= pmu_nvram_write_byte;
615 		ppc_md.nvram_size	= ppc32_nvram_size;
616 #endif /* CONFIG_ADB_PMU */
617 	} else {
618 		printk(KERN_ERR "Incompatible type of NVRAM\n");
619 		err = -ENXIO;
620 	}
621 #endif /* CONFIG_PPC32 */
622 bail:
623 	of_node_put(dp);
624 	if (err == 0)
625 		lookup_partitions();
626 	return err;
627 }
628 
pmac_get_partition(int partition)629 int pmac_get_partition(int partition)
630 {
631 	return nvram_partitions[partition];
632 }
633 
pmac_xpram_read(int xpaddr)634 u8 pmac_xpram_read(int xpaddr)
635 {
636 	int offset = pmac_get_partition(pmac_nvram_XPRAM);
637 
638 	if (offset < 0 || xpaddr < 0 || xpaddr > 0x100)
639 		return 0xff;
640 
641 	return ppc_md.nvram_read_val(xpaddr + offset);
642 }
643 
pmac_xpram_write(int xpaddr,u8 data)644 void pmac_xpram_write(int xpaddr, u8 data)
645 {
646 	int offset = pmac_get_partition(pmac_nvram_XPRAM);
647 
648 	if (offset < 0 || xpaddr < 0 || xpaddr > 0x100)
649 		return;
650 
651 	ppc_md.nvram_write_val(xpaddr + offset, data);
652 }
653 
654 EXPORT_SYMBOL(pmac_get_partition);
655 EXPORT_SYMBOL(pmac_xpram_read);
656 EXPORT_SYMBOL(pmac_xpram_write);
657