xref: /openbmc/linux/arch/x86/kernel/amd_nb.c (revision 48cc39c3)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Shared support code for AMD K8 northbridges and derivatives.
4  * Copyright 2006 Andi Kleen, SUSE Labs.
5  */
6 
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8 
9 #include <linux/types.h>
10 #include <linux/slab.h>
11 #include <linux/init.h>
12 #include <linux/errno.h>
13 #include <linux/export.h>
14 #include <linux/spinlock.h>
15 #include <linux/pci_ids.h>
16 #include <asm/amd_nb.h>
17 
18 #define PCI_DEVICE_ID_AMD_17H_ROOT	0x1450
19 #define PCI_DEVICE_ID_AMD_17H_M10H_ROOT	0x15d0
20 #define PCI_DEVICE_ID_AMD_17H_M30H_ROOT	0x1480
21 #define PCI_DEVICE_ID_AMD_17H_M60H_ROOT	0x1630
22 #define PCI_DEVICE_ID_AMD_17H_DF_F4	0x1464
23 #define PCI_DEVICE_ID_AMD_17H_M10H_DF_F4 0x15ec
24 #define PCI_DEVICE_ID_AMD_17H_M30H_DF_F4 0x1494
25 #define PCI_DEVICE_ID_AMD_17H_M60H_DF_F4 0x144c
26 #define PCI_DEVICE_ID_AMD_17H_M70H_DF_F4 0x1444
27 #define PCI_DEVICE_ID_AMD_19H_DF_F4	0x1654
28 #define PCI_DEVICE_ID_AMD_19H_M40H_ROOT	0x14b5
29 #define PCI_DEVICE_ID_AMD_19H_M40H_DF_F4 0x167d
30 #define PCI_DEVICE_ID_AMD_19H_M50H_DF_F4 0x166e
31 
32 /* Protect the PCI config register pairs used for SMN and DF indirect access. */
33 static DEFINE_MUTEX(smn_mutex);
34 
35 static u32 *flush_words;
36 
37 static const struct pci_device_id amd_root_ids[] = {
38 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_ROOT) },
39 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M10H_ROOT) },
40 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M30H_ROOT) },
41 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M60H_ROOT) },
42 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_ROOT) },
43 	{}
44 };
45 
46 #define PCI_DEVICE_ID_AMD_CNB17H_F4     0x1704
47 
48 static const struct pci_device_id amd_nb_misc_ids[] = {
49 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB_MISC) },
50 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_10H_NB_MISC) },
51 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F3) },
52 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M10H_F3) },
53 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F3) },
54 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M60H_NB_F3) },
55 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F3) },
56 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_M30H_NB_F3) },
57 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_DF_F3) },
58 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M10H_DF_F3) },
59 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M30H_DF_F3) },
60 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M60H_DF_F3) },
61 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CNB17H_F3) },
62 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M70H_DF_F3) },
63 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_DF_F3) },
64 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_DF_F3) },
65 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M50H_DF_F3) },
66 	{}
67 };
68 
69 static const struct pci_device_id amd_nb_link_ids[] = {
70 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) },
71 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F4) },
72 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M60H_NB_F4) },
73 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F4) },
74 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_M30H_NB_F4) },
75 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_DF_F4) },
76 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M10H_DF_F4) },
77 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M30H_DF_F4) },
78 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M60H_DF_F4) },
79 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M70H_DF_F4) },
80 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_DF_F4) },
81 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_DF_F4) },
82 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M50H_DF_F4) },
83 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CNB17H_F4) },
84 	{}
85 };
86 
87 static const struct pci_device_id hygon_root_ids[] = {
88 	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_17H_ROOT) },
89 	{}
90 };
91 
92 static const struct pci_device_id hygon_nb_misc_ids[] = {
93 	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_17H_DF_F3) },
94 	{}
95 };
96 
97 static const struct pci_device_id hygon_nb_link_ids[] = {
98 	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_17H_DF_F4) },
99 	{}
100 };
101 
102 const struct amd_nb_bus_dev_range amd_nb_bus_dev_ranges[] __initconst = {
103 	{ 0x00, 0x18, 0x20 },
104 	{ 0xff, 0x00, 0x20 },
105 	{ 0xfe, 0x00, 0x20 },
106 	{ }
107 };
108 
109 static struct amd_northbridge_info amd_northbridges;
110 
111 u16 amd_nb_num(void)
112 {
113 	return amd_northbridges.num;
114 }
115 EXPORT_SYMBOL_GPL(amd_nb_num);
116 
117 bool amd_nb_has_feature(unsigned int feature)
118 {
119 	return ((amd_northbridges.flags & feature) == feature);
120 }
121 EXPORT_SYMBOL_GPL(amd_nb_has_feature);
122 
123 struct amd_northbridge *node_to_amd_nb(int node)
124 {
125 	return (node < amd_northbridges.num) ? &amd_northbridges.nb[node] : NULL;
126 }
127 EXPORT_SYMBOL_GPL(node_to_amd_nb);
128 
129 static struct pci_dev *next_northbridge(struct pci_dev *dev,
130 					const struct pci_device_id *ids)
131 {
132 	do {
133 		dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
134 		if (!dev)
135 			break;
136 	} while (!pci_match_id(ids, dev));
137 	return dev;
138 }
139 
140 static int __amd_smn_rw(u16 node, u32 address, u32 *value, bool write)
141 {
142 	struct pci_dev *root;
143 	int err = -ENODEV;
144 
145 	if (node >= amd_northbridges.num)
146 		goto out;
147 
148 	root = node_to_amd_nb(node)->root;
149 	if (!root)
150 		goto out;
151 
152 	mutex_lock(&smn_mutex);
153 
154 	err = pci_write_config_dword(root, 0x60, address);
155 	if (err) {
156 		pr_warn("Error programming SMN address 0x%x.\n", address);
157 		goto out_unlock;
158 	}
159 
160 	err = (write ? pci_write_config_dword(root, 0x64, *value)
161 		     : pci_read_config_dword(root, 0x64, value));
162 	if (err)
163 		pr_warn("Error %s SMN address 0x%x.\n",
164 			(write ? "writing to" : "reading from"), address);
165 
166 out_unlock:
167 	mutex_unlock(&smn_mutex);
168 
169 out:
170 	return err;
171 }
172 
173 int amd_smn_read(u16 node, u32 address, u32 *value)
174 {
175 	return __amd_smn_rw(node, address, value, false);
176 }
177 EXPORT_SYMBOL_GPL(amd_smn_read);
178 
179 int amd_smn_write(u16 node, u32 address, u32 value)
180 {
181 	return __amd_smn_rw(node, address, &value, true);
182 }
183 EXPORT_SYMBOL_GPL(amd_smn_write);
184 
185 /*
186  * Data Fabric Indirect Access uses FICAA/FICAD.
187  *
188  * Fabric Indirect Configuration Access Address (FICAA): Constructed based
189  * on the device's Instance Id and the PCI function and register offset of
190  * the desired register.
191  *
192  * Fabric Indirect Configuration Access Data (FICAD): There are FICAD LO
193  * and FICAD HI registers but so far we only need the LO register.
194  */
195 int amd_df_indirect_read(u16 node, u8 func, u16 reg, u8 instance_id, u32 *lo)
196 {
197 	struct pci_dev *F4;
198 	u32 ficaa;
199 	int err = -ENODEV;
200 
201 	if (node >= amd_northbridges.num)
202 		goto out;
203 
204 	F4 = node_to_amd_nb(node)->link;
205 	if (!F4)
206 		goto out;
207 
208 	ficaa  = 1;
209 	ficaa |= reg & 0x3FC;
210 	ficaa |= (func & 0x7) << 11;
211 	ficaa |= instance_id << 16;
212 
213 	mutex_lock(&smn_mutex);
214 
215 	err = pci_write_config_dword(F4, 0x5C, ficaa);
216 	if (err) {
217 		pr_warn("Error writing DF Indirect FICAA, FICAA=0x%x\n", ficaa);
218 		goto out_unlock;
219 	}
220 
221 	err = pci_read_config_dword(F4, 0x98, lo);
222 	if (err)
223 		pr_warn("Error reading DF Indirect FICAD LO, FICAA=0x%x.\n", ficaa);
224 
225 out_unlock:
226 	mutex_unlock(&smn_mutex);
227 
228 out:
229 	return err;
230 }
231 EXPORT_SYMBOL_GPL(amd_df_indirect_read);
232 
233 int amd_cache_northbridges(void)
234 {
235 	const struct pci_device_id *misc_ids = amd_nb_misc_ids;
236 	const struct pci_device_id *link_ids = amd_nb_link_ids;
237 	const struct pci_device_id *root_ids = amd_root_ids;
238 	struct pci_dev *root, *misc, *link;
239 	struct amd_northbridge *nb;
240 	u16 roots_per_misc = 0;
241 	u16 misc_count = 0;
242 	u16 root_count = 0;
243 	u16 i, j;
244 
245 	if (amd_northbridges.num)
246 		return 0;
247 
248 	if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
249 		root_ids = hygon_root_ids;
250 		misc_ids = hygon_nb_misc_ids;
251 		link_ids = hygon_nb_link_ids;
252 	}
253 
254 	misc = NULL;
255 	while ((misc = next_northbridge(misc, misc_ids)) != NULL)
256 		misc_count++;
257 
258 	if (!misc_count)
259 		return -ENODEV;
260 
261 	root = NULL;
262 	while ((root = next_northbridge(root, root_ids)) != NULL)
263 		root_count++;
264 
265 	if (root_count) {
266 		roots_per_misc = root_count / misc_count;
267 
268 		/*
269 		 * There should be _exactly_ N roots for each DF/SMN
270 		 * interface.
271 		 */
272 		if (!roots_per_misc || (root_count % roots_per_misc)) {
273 			pr_info("Unsupported AMD DF/PCI configuration found\n");
274 			return -ENODEV;
275 		}
276 	}
277 
278 	nb = kcalloc(misc_count, sizeof(struct amd_northbridge), GFP_KERNEL);
279 	if (!nb)
280 		return -ENOMEM;
281 
282 	amd_northbridges.nb = nb;
283 	amd_northbridges.num = misc_count;
284 
285 	link = misc = root = NULL;
286 	for (i = 0; i < amd_northbridges.num; i++) {
287 		node_to_amd_nb(i)->root = root =
288 			next_northbridge(root, root_ids);
289 		node_to_amd_nb(i)->misc = misc =
290 			next_northbridge(misc, misc_ids);
291 		node_to_amd_nb(i)->link = link =
292 			next_northbridge(link, link_ids);
293 
294 		/*
295 		 * If there are more PCI root devices than data fabric/
296 		 * system management network interfaces, then the (N)
297 		 * PCI roots per DF/SMN interface are functionally the
298 		 * same (for DF/SMN access) and N-1 are redundant.  N-1
299 		 * PCI roots should be skipped per DF/SMN interface so
300 		 * the following DF/SMN interfaces get mapped to
301 		 * correct PCI roots.
302 		 */
303 		for (j = 1; j < roots_per_misc; j++)
304 			root = next_northbridge(root, root_ids);
305 	}
306 
307 	if (amd_gart_present())
308 		amd_northbridges.flags |= AMD_NB_GART;
309 
310 	/*
311 	 * Check for L3 cache presence.
312 	 */
313 	if (!cpuid_edx(0x80000006))
314 		return 0;
315 
316 	/*
317 	 * Some CPU families support L3 Cache Index Disable. There are some
318 	 * limitations because of E382 and E388 on family 0x10.
319 	 */
320 	if (boot_cpu_data.x86 == 0x10 &&
321 	    boot_cpu_data.x86_model >= 0x8 &&
322 	    (boot_cpu_data.x86_model > 0x9 ||
323 	     boot_cpu_data.x86_stepping >= 0x1))
324 		amd_northbridges.flags |= AMD_NB_L3_INDEX_DISABLE;
325 
326 	if (boot_cpu_data.x86 == 0x15)
327 		amd_northbridges.flags |= AMD_NB_L3_INDEX_DISABLE;
328 
329 	/* L3 cache partitioning is supported on family 0x15 */
330 	if (boot_cpu_data.x86 == 0x15)
331 		amd_northbridges.flags |= AMD_NB_L3_PARTITIONING;
332 
333 	return 0;
334 }
335 EXPORT_SYMBOL_GPL(amd_cache_northbridges);
336 
337 /*
338  * Ignores subdevice/subvendor but as far as I can figure out
339  * they're useless anyways
340  */
341 bool __init early_is_amd_nb(u32 device)
342 {
343 	const struct pci_device_id *misc_ids = amd_nb_misc_ids;
344 	const struct pci_device_id *id;
345 	u32 vendor = device & 0xffff;
346 
347 	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
348 	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
349 		return false;
350 
351 	if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
352 		misc_ids = hygon_nb_misc_ids;
353 
354 	device >>= 16;
355 	for (id = misc_ids; id->vendor; id++)
356 		if (vendor == id->vendor && device == id->device)
357 			return true;
358 	return false;
359 }
360 
361 struct resource *amd_get_mmconfig_range(struct resource *res)
362 {
363 	u32 address;
364 	u64 base, msr;
365 	unsigned int segn_busn_bits;
366 
367 	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
368 	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
369 		return NULL;
370 
371 	/* assume all cpus from fam10h have mmconfig */
372 	if (boot_cpu_data.x86 < 0x10)
373 		return NULL;
374 
375 	address = MSR_FAM10H_MMIO_CONF_BASE;
376 	rdmsrl(address, msr);
377 
378 	/* mmconfig is not enabled */
379 	if (!(msr & FAM10H_MMIO_CONF_ENABLE))
380 		return NULL;
381 
382 	base = msr & (FAM10H_MMIO_CONF_BASE_MASK<<FAM10H_MMIO_CONF_BASE_SHIFT);
383 
384 	segn_busn_bits = (msr >> FAM10H_MMIO_CONF_BUSRANGE_SHIFT) &
385 			 FAM10H_MMIO_CONF_BUSRANGE_MASK;
386 
387 	res->flags = IORESOURCE_MEM;
388 	res->start = base;
389 	res->end = base + (1ULL<<(segn_busn_bits + 20)) - 1;
390 	return res;
391 }
392 
393 int amd_get_subcaches(int cpu)
394 {
395 	struct pci_dev *link = node_to_amd_nb(topology_die_id(cpu))->link;
396 	unsigned int mask;
397 
398 	if (!amd_nb_has_feature(AMD_NB_L3_PARTITIONING))
399 		return 0;
400 
401 	pci_read_config_dword(link, 0x1d4, &mask);
402 
403 	return (mask >> (4 * cpu_data(cpu).cpu_core_id)) & 0xf;
404 }
405 
406 int amd_set_subcaches(int cpu, unsigned long mask)
407 {
408 	static unsigned int reset, ban;
409 	struct amd_northbridge *nb = node_to_amd_nb(topology_die_id(cpu));
410 	unsigned int reg;
411 	int cuid;
412 
413 	if (!amd_nb_has_feature(AMD_NB_L3_PARTITIONING) || mask > 0xf)
414 		return -EINVAL;
415 
416 	/* if necessary, collect reset state of L3 partitioning and BAN mode */
417 	if (reset == 0) {
418 		pci_read_config_dword(nb->link, 0x1d4, &reset);
419 		pci_read_config_dword(nb->misc, 0x1b8, &ban);
420 		ban &= 0x180000;
421 	}
422 
423 	/* deactivate BAN mode if any subcaches are to be disabled */
424 	if (mask != 0xf) {
425 		pci_read_config_dword(nb->misc, 0x1b8, &reg);
426 		pci_write_config_dword(nb->misc, 0x1b8, reg & ~0x180000);
427 	}
428 
429 	cuid = cpu_data(cpu).cpu_core_id;
430 	mask <<= 4 * cuid;
431 	mask |= (0xf ^ (1 << cuid)) << 26;
432 
433 	pci_write_config_dword(nb->link, 0x1d4, mask);
434 
435 	/* reset BAN mode if L3 partitioning returned to reset state */
436 	pci_read_config_dword(nb->link, 0x1d4, &reg);
437 	if (reg == reset) {
438 		pci_read_config_dword(nb->misc, 0x1b8, &reg);
439 		reg &= ~0x180000;
440 		pci_write_config_dword(nb->misc, 0x1b8, reg | ban);
441 	}
442 
443 	return 0;
444 }
445 
446 static void amd_cache_gart(void)
447 {
448 	u16 i;
449 
450 	if (!amd_nb_has_feature(AMD_NB_GART))
451 		return;
452 
453 	flush_words = kmalloc_array(amd_northbridges.num, sizeof(u32), GFP_KERNEL);
454 	if (!flush_words) {
455 		amd_northbridges.flags &= ~AMD_NB_GART;
456 		pr_notice("Cannot initialize GART flush words, GART support disabled\n");
457 		return;
458 	}
459 
460 	for (i = 0; i != amd_northbridges.num; i++)
461 		pci_read_config_dword(node_to_amd_nb(i)->misc, 0x9c, &flush_words[i]);
462 }
463 
464 void amd_flush_garts(void)
465 {
466 	int flushed, i;
467 	unsigned long flags;
468 	static DEFINE_SPINLOCK(gart_lock);
469 
470 	if (!amd_nb_has_feature(AMD_NB_GART))
471 		return;
472 
473 	/*
474 	 * Avoid races between AGP and IOMMU. In theory it's not needed
475 	 * but I'm not sure if the hardware won't lose flush requests
476 	 * when another is pending. This whole thing is so expensive anyways
477 	 * that it doesn't matter to serialize more. -AK
478 	 */
479 	spin_lock_irqsave(&gart_lock, flags);
480 	flushed = 0;
481 	for (i = 0; i < amd_northbridges.num; i++) {
482 		pci_write_config_dword(node_to_amd_nb(i)->misc, 0x9c,
483 				       flush_words[i] | 1);
484 		flushed++;
485 	}
486 	for (i = 0; i < amd_northbridges.num; i++) {
487 		u32 w;
488 		/* Make sure the hardware actually executed the flush*/
489 		for (;;) {
490 			pci_read_config_dword(node_to_amd_nb(i)->misc,
491 					      0x9c, &w);
492 			if (!(w & 1))
493 				break;
494 			cpu_relax();
495 		}
496 	}
497 	spin_unlock_irqrestore(&gart_lock, flags);
498 	if (!flushed)
499 		pr_notice("nothing to flush?\n");
500 }
501 EXPORT_SYMBOL_GPL(amd_flush_garts);
502 
503 static void __fix_erratum_688(void *info)
504 {
505 #define MSR_AMD64_IC_CFG 0xC0011021
506 
507 	msr_set_bit(MSR_AMD64_IC_CFG, 3);
508 	msr_set_bit(MSR_AMD64_IC_CFG, 14);
509 }
510 
511 /* Apply erratum 688 fix so machines without a BIOS fix work. */
512 static __init void fix_erratum_688(void)
513 {
514 	struct pci_dev *F4;
515 	u32 val;
516 
517 	if (boot_cpu_data.x86 != 0x14)
518 		return;
519 
520 	if (!amd_northbridges.num)
521 		return;
522 
523 	F4 = node_to_amd_nb(0)->link;
524 	if (!F4)
525 		return;
526 
527 	if (pci_read_config_dword(F4, 0x164, &val))
528 		return;
529 
530 	if (val & BIT(2))
531 		return;
532 
533 	on_each_cpu(__fix_erratum_688, NULL, 0);
534 
535 	pr_info("x86/cpu/AMD: CPU erratum 688 worked around\n");
536 }
537 
538 static __init int init_amd_nbs(void)
539 {
540 	amd_cache_northbridges();
541 	amd_cache_gart();
542 
543 	fix_erratum_688();
544 
545 	return 0;
546 }
547 
548 /* This has to go after the PCI subsystem */
549 fs_initcall(init_amd_nbs);
550