xref: /linux/arch/x86/kernel/amd_nb.c (revision 122333d6bd229af279cdb35d1b874b71b3b9ccfb)
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_MA0H_ROOT	0x14b5
23 #define PCI_DEVICE_ID_AMD_19H_M10H_ROOT	0x14a4
24 #define PCI_DEVICE_ID_AMD_19H_M60H_ROOT	0x14d8
25 #define PCI_DEVICE_ID_AMD_19H_M70H_ROOT	0x14e8
26 #define PCI_DEVICE_ID_AMD_17H_DF_F4	0x1464
27 #define PCI_DEVICE_ID_AMD_17H_M10H_DF_F4 0x15ec
28 #define PCI_DEVICE_ID_AMD_17H_M30H_DF_F4 0x1494
29 #define PCI_DEVICE_ID_AMD_17H_M60H_DF_F4 0x144c
30 #define PCI_DEVICE_ID_AMD_17H_M70H_DF_F4 0x1444
31 #define PCI_DEVICE_ID_AMD_17H_MA0H_DF_F4 0x1728
32 #define PCI_DEVICE_ID_AMD_19H_DF_F4	0x1654
33 #define PCI_DEVICE_ID_AMD_19H_M10H_DF_F4 0x14b1
34 #define PCI_DEVICE_ID_AMD_19H_M40H_ROOT	0x14b5
35 #define PCI_DEVICE_ID_AMD_19H_M40H_DF_F4 0x167d
36 #define PCI_DEVICE_ID_AMD_19H_M50H_DF_F4 0x166e
37 #define PCI_DEVICE_ID_AMD_19H_M60H_DF_F4 0x14e4
38 #define PCI_DEVICE_ID_AMD_19H_M70H_DF_F4 0x14f4
39 #define PCI_DEVICE_ID_AMD_19H_M78H_DF_F4 0x12fc
40 
41 /* Protect the PCI config register pairs used for SMN. */
42 static DEFINE_MUTEX(smn_mutex);
43 
44 static u32 *flush_words;
45 
46 static const struct pci_device_id amd_root_ids[] = {
47 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_ROOT) },
48 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M10H_ROOT) },
49 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M30H_ROOT) },
50 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M60H_ROOT) },
51 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_MA0H_ROOT) },
52 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M10H_ROOT) },
53 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_ROOT) },
54 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M60H_ROOT) },
55 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M70H_ROOT) },
56 	{}
57 };
58 
59 #define PCI_DEVICE_ID_AMD_CNB17H_F4     0x1704
60 
61 static const struct pci_device_id amd_nb_misc_ids[] = {
62 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB_MISC) },
63 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_10H_NB_MISC) },
64 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F3) },
65 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M10H_F3) },
66 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F3) },
67 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M60H_NB_F3) },
68 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F3) },
69 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_M30H_NB_F3) },
70 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_DF_F3) },
71 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M10H_DF_F3) },
72 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M30H_DF_F3) },
73 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M60H_DF_F3) },
74 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_MA0H_DF_F3) },
75 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CNB17H_F3) },
76 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M70H_DF_F3) },
77 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_DF_F3) },
78 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M10H_DF_F3) },
79 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_DF_F3) },
80 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M50H_DF_F3) },
81 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M60H_DF_F3) },
82 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M70H_DF_F3) },
83 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M78H_DF_F3) },
84 	{}
85 };
86 
87 static const struct pci_device_id amd_nb_link_ids[] = {
88 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) },
89 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F4) },
90 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M60H_NB_F4) },
91 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F4) },
92 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_M30H_NB_F4) },
93 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_DF_F4) },
94 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M10H_DF_F4) },
95 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M30H_DF_F4) },
96 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M60H_DF_F4) },
97 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M70H_DF_F4) },
98 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_MA0H_DF_F4) },
99 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_DF_F4) },
100 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M10H_DF_F4) },
101 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_DF_F4) },
102 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M50H_DF_F4) },
103 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CNB17H_F4) },
104 	{}
105 };
106 
107 static const struct pci_device_id hygon_root_ids[] = {
108 	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_17H_ROOT) },
109 	{}
110 };
111 
112 static const struct pci_device_id hygon_nb_misc_ids[] = {
113 	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_17H_DF_F3) },
114 	{}
115 };
116 
117 static const struct pci_device_id hygon_nb_link_ids[] = {
118 	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_17H_DF_F4) },
119 	{}
120 };
121 
122 const struct amd_nb_bus_dev_range amd_nb_bus_dev_ranges[] __initconst = {
123 	{ 0x00, 0x18, 0x20 },
124 	{ 0xff, 0x00, 0x20 },
125 	{ 0xfe, 0x00, 0x20 },
126 	{ }
127 };
128 
129 static struct amd_northbridge_info amd_northbridges;
130 
131 u16 amd_nb_num(void)
132 {
133 	return amd_northbridges.num;
134 }
135 EXPORT_SYMBOL_GPL(amd_nb_num);
136 
137 bool amd_nb_has_feature(unsigned int feature)
138 {
139 	return ((amd_northbridges.flags & feature) == feature);
140 }
141 EXPORT_SYMBOL_GPL(amd_nb_has_feature);
142 
143 struct amd_northbridge *node_to_amd_nb(int node)
144 {
145 	return (node < amd_northbridges.num) ? &amd_northbridges.nb[node] : NULL;
146 }
147 EXPORT_SYMBOL_GPL(node_to_amd_nb);
148 
149 static struct pci_dev *next_northbridge(struct pci_dev *dev,
150 					const struct pci_device_id *ids)
151 {
152 	do {
153 		dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
154 		if (!dev)
155 			break;
156 	} while (!pci_match_id(ids, dev));
157 	return dev;
158 }
159 
160 static int __amd_smn_rw(u16 node, u32 address, u32 *value, bool write)
161 {
162 	struct pci_dev *root;
163 	int err = -ENODEV;
164 
165 	if (node >= amd_northbridges.num)
166 		goto out;
167 
168 	root = node_to_amd_nb(node)->root;
169 	if (!root)
170 		goto out;
171 
172 	mutex_lock(&smn_mutex);
173 
174 	err = pci_write_config_dword(root, 0x60, address);
175 	if (err) {
176 		pr_warn("Error programming SMN address 0x%x.\n", address);
177 		goto out_unlock;
178 	}
179 
180 	err = (write ? pci_write_config_dword(root, 0x64, *value)
181 		     : pci_read_config_dword(root, 0x64, value));
182 	if (err)
183 		pr_warn("Error %s SMN address 0x%x.\n",
184 			(write ? "writing to" : "reading from"), address);
185 
186 out_unlock:
187 	mutex_unlock(&smn_mutex);
188 
189 out:
190 	return err;
191 }
192 
193 int amd_smn_read(u16 node, u32 address, u32 *value)
194 {
195 	return __amd_smn_rw(node, address, value, false);
196 }
197 EXPORT_SYMBOL_GPL(amd_smn_read);
198 
199 int amd_smn_write(u16 node, u32 address, u32 value)
200 {
201 	return __amd_smn_rw(node, address, &value, true);
202 }
203 EXPORT_SYMBOL_GPL(amd_smn_write);
204 
205 
206 static int amd_cache_northbridges(void)
207 {
208 	const struct pci_device_id *misc_ids = amd_nb_misc_ids;
209 	const struct pci_device_id *link_ids = amd_nb_link_ids;
210 	const struct pci_device_id *root_ids = amd_root_ids;
211 	struct pci_dev *root, *misc, *link;
212 	struct amd_northbridge *nb;
213 	u16 roots_per_misc = 0;
214 	u16 misc_count = 0;
215 	u16 root_count = 0;
216 	u16 i, j;
217 
218 	if (amd_northbridges.num)
219 		return 0;
220 
221 	if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
222 		root_ids = hygon_root_ids;
223 		misc_ids = hygon_nb_misc_ids;
224 		link_ids = hygon_nb_link_ids;
225 	}
226 
227 	misc = NULL;
228 	while ((misc = next_northbridge(misc, misc_ids)))
229 		misc_count++;
230 
231 	if (!misc_count)
232 		return -ENODEV;
233 
234 	root = NULL;
235 	while ((root = next_northbridge(root, root_ids)))
236 		root_count++;
237 
238 	if (root_count) {
239 		roots_per_misc = root_count / misc_count;
240 
241 		/*
242 		 * There should be _exactly_ N roots for each DF/SMN
243 		 * interface.
244 		 */
245 		if (!roots_per_misc || (root_count % roots_per_misc)) {
246 			pr_info("Unsupported AMD DF/PCI configuration found\n");
247 			return -ENODEV;
248 		}
249 	}
250 
251 	nb = kcalloc(misc_count, sizeof(struct amd_northbridge), GFP_KERNEL);
252 	if (!nb)
253 		return -ENOMEM;
254 
255 	amd_northbridges.nb = nb;
256 	amd_northbridges.num = misc_count;
257 
258 	link = misc = root = NULL;
259 	for (i = 0; i < amd_northbridges.num; i++) {
260 		node_to_amd_nb(i)->root = root =
261 			next_northbridge(root, root_ids);
262 		node_to_amd_nb(i)->misc = misc =
263 			next_northbridge(misc, misc_ids);
264 		node_to_amd_nb(i)->link = link =
265 			next_northbridge(link, link_ids);
266 
267 		/*
268 		 * If there are more PCI root devices than data fabric/
269 		 * system management network interfaces, then the (N)
270 		 * PCI roots per DF/SMN interface are functionally the
271 		 * same (for DF/SMN access) and N-1 are redundant.  N-1
272 		 * PCI roots should be skipped per DF/SMN interface so
273 		 * the following DF/SMN interfaces get mapped to
274 		 * correct PCI roots.
275 		 */
276 		for (j = 1; j < roots_per_misc; j++)
277 			root = next_northbridge(root, root_ids);
278 	}
279 
280 	if (amd_gart_present())
281 		amd_northbridges.flags |= AMD_NB_GART;
282 
283 	/*
284 	 * Check for L3 cache presence.
285 	 */
286 	if (!cpuid_edx(0x80000006))
287 		return 0;
288 
289 	/*
290 	 * Some CPU families support L3 Cache Index Disable. There are some
291 	 * limitations because of E382 and E388 on family 0x10.
292 	 */
293 	if (boot_cpu_data.x86 == 0x10 &&
294 	    boot_cpu_data.x86_model >= 0x8 &&
295 	    (boot_cpu_data.x86_model > 0x9 ||
296 	     boot_cpu_data.x86_stepping >= 0x1))
297 		amd_northbridges.flags |= AMD_NB_L3_INDEX_DISABLE;
298 
299 	if (boot_cpu_data.x86 == 0x15)
300 		amd_northbridges.flags |= AMD_NB_L3_INDEX_DISABLE;
301 
302 	/* L3 cache partitioning is supported on family 0x15 */
303 	if (boot_cpu_data.x86 == 0x15)
304 		amd_northbridges.flags |= AMD_NB_L3_PARTITIONING;
305 
306 	return 0;
307 }
308 
309 /*
310  * Ignores subdevice/subvendor but as far as I can figure out
311  * they're useless anyways
312  */
313 bool __init early_is_amd_nb(u32 device)
314 {
315 	const struct pci_device_id *misc_ids = amd_nb_misc_ids;
316 	const struct pci_device_id *id;
317 	u32 vendor = device & 0xffff;
318 
319 	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
320 	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
321 		return false;
322 
323 	if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
324 		misc_ids = hygon_nb_misc_ids;
325 
326 	device >>= 16;
327 	for (id = misc_ids; id->vendor; id++)
328 		if (vendor == id->vendor && device == id->device)
329 			return true;
330 	return false;
331 }
332 
333 struct resource *amd_get_mmconfig_range(struct resource *res)
334 {
335 	u32 address;
336 	u64 base, msr;
337 	unsigned int segn_busn_bits;
338 
339 	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
340 	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
341 		return NULL;
342 
343 	/* assume all cpus from fam10h have mmconfig */
344 	if (boot_cpu_data.x86 < 0x10)
345 		return NULL;
346 
347 	address = MSR_FAM10H_MMIO_CONF_BASE;
348 	rdmsrl(address, msr);
349 
350 	/* mmconfig is not enabled */
351 	if (!(msr & FAM10H_MMIO_CONF_ENABLE))
352 		return NULL;
353 
354 	base = msr & (FAM10H_MMIO_CONF_BASE_MASK<<FAM10H_MMIO_CONF_BASE_SHIFT);
355 
356 	segn_busn_bits = (msr >> FAM10H_MMIO_CONF_BUSRANGE_SHIFT) &
357 			 FAM10H_MMIO_CONF_BUSRANGE_MASK;
358 
359 	res->flags = IORESOURCE_MEM;
360 	res->start = base;
361 	res->end = base + (1ULL<<(segn_busn_bits + 20)) - 1;
362 	return res;
363 }
364 
365 int amd_get_subcaches(int cpu)
366 {
367 	struct pci_dev *link = node_to_amd_nb(topology_die_id(cpu))->link;
368 	unsigned int mask;
369 
370 	if (!amd_nb_has_feature(AMD_NB_L3_PARTITIONING))
371 		return 0;
372 
373 	pci_read_config_dword(link, 0x1d4, &mask);
374 
375 	return (mask >> (4 * cpu_data(cpu).cpu_core_id)) & 0xf;
376 }
377 
378 int amd_set_subcaches(int cpu, unsigned long mask)
379 {
380 	static unsigned int reset, ban;
381 	struct amd_northbridge *nb = node_to_amd_nb(topology_die_id(cpu));
382 	unsigned int reg;
383 	int cuid;
384 
385 	if (!amd_nb_has_feature(AMD_NB_L3_PARTITIONING) || mask > 0xf)
386 		return -EINVAL;
387 
388 	/* if necessary, collect reset state of L3 partitioning and BAN mode */
389 	if (reset == 0) {
390 		pci_read_config_dword(nb->link, 0x1d4, &reset);
391 		pci_read_config_dword(nb->misc, 0x1b8, &ban);
392 		ban &= 0x180000;
393 	}
394 
395 	/* deactivate BAN mode if any subcaches are to be disabled */
396 	if (mask != 0xf) {
397 		pci_read_config_dword(nb->misc, 0x1b8, &reg);
398 		pci_write_config_dword(nb->misc, 0x1b8, reg & ~0x180000);
399 	}
400 
401 	cuid = cpu_data(cpu).cpu_core_id;
402 	mask <<= 4 * cuid;
403 	mask |= (0xf ^ (1 << cuid)) << 26;
404 
405 	pci_write_config_dword(nb->link, 0x1d4, mask);
406 
407 	/* reset BAN mode if L3 partitioning returned to reset state */
408 	pci_read_config_dword(nb->link, 0x1d4, &reg);
409 	if (reg == reset) {
410 		pci_read_config_dword(nb->misc, 0x1b8, &reg);
411 		reg &= ~0x180000;
412 		pci_write_config_dword(nb->misc, 0x1b8, reg | ban);
413 	}
414 
415 	return 0;
416 }
417 
418 static void amd_cache_gart(void)
419 {
420 	u16 i;
421 
422 	if (!amd_nb_has_feature(AMD_NB_GART))
423 		return;
424 
425 	flush_words = kmalloc_array(amd_northbridges.num, sizeof(u32), GFP_KERNEL);
426 	if (!flush_words) {
427 		amd_northbridges.flags &= ~AMD_NB_GART;
428 		pr_notice("Cannot initialize GART flush words, GART support disabled\n");
429 		return;
430 	}
431 
432 	for (i = 0; i != amd_northbridges.num; i++)
433 		pci_read_config_dword(node_to_amd_nb(i)->misc, 0x9c, &flush_words[i]);
434 }
435 
436 void amd_flush_garts(void)
437 {
438 	int flushed, i;
439 	unsigned long flags;
440 	static DEFINE_SPINLOCK(gart_lock);
441 
442 	if (!amd_nb_has_feature(AMD_NB_GART))
443 		return;
444 
445 	/*
446 	 * Avoid races between AGP and IOMMU. In theory it's not needed
447 	 * but I'm not sure if the hardware won't lose flush requests
448 	 * when another is pending. This whole thing is so expensive anyways
449 	 * that it doesn't matter to serialize more. -AK
450 	 */
451 	spin_lock_irqsave(&gart_lock, flags);
452 	flushed = 0;
453 	for (i = 0; i < amd_northbridges.num; i++) {
454 		pci_write_config_dword(node_to_amd_nb(i)->misc, 0x9c,
455 				       flush_words[i] | 1);
456 		flushed++;
457 	}
458 	for (i = 0; i < amd_northbridges.num; i++) {
459 		u32 w;
460 		/* Make sure the hardware actually executed the flush*/
461 		for (;;) {
462 			pci_read_config_dword(node_to_amd_nb(i)->misc,
463 					      0x9c, &w);
464 			if (!(w & 1))
465 				break;
466 			cpu_relax();
467 		}
468 	}
469 	spin_unlock_irqrestore(&gart_lock, flags);
470 	if (!flushed)
471 		pr_notice("nothing to flush?\n");
472 }
473 EXPORT_SYMBOL_GPL(amd_flush_garts);
474 
475 static void __fix_erratum_688(void *info)
476 {
477 #define MSR_AMD64_IC_CFG 0xC0011021
478 
479 	msr_set_bit(MSR_AMD64_IC_CFG, 3);
480 	msr_set_bit(MSR_AMD64_IC_CFG, 14);
481 }
482 
483 /* Apply erratum 688 fix so machines without a BIOS fix work. */
484 static __init void fix_erratum_688(void)
485 {
486 	struct pci_dev *F4;
487 	u32 val;
488 
489 	if (boot_cpu_data.x86 != 0x14)
490 		return;
491 
492 	if (!amd_northbridges.num)
493 		return;
494 
495 	F4 = node_to_amd_nb(0)->link;
496 	if (!F4)
497 		return;
498 
499 	if (pci_read_config_dword(F4, 0x164, &val))
500 		return;
501 
502 	if (val & BIT(2))
503 		return;
504 
505 	on_each_cpu(__fix_erratum_688, NULL, 0);
506 
507 	pr_info("x86/cpu/AMD: CPU erratum 688 worked around\n");
508 }
509 
510 static __init int init_amd_nbs(void)
511 {
512 	amd_cache_northbridges();
513 	amd_cache_gart();
514 
515 	fix_erratum_688();
516 
517 	return 0;
518 }
519 
520 /* This has to go after the PCI subsystem */
521 fs_initcall(init_amd_nbs);
522