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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * PCI Virtual Channel support
4 *
5 * Copyright (C) 2013 Red Hat, Inc. All rights reserved.
6 * Author: Alex Williamson <alex.williamson@redhat.com>
7 */
8
9#include <linux/device.h>
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/pci.h>
13#include <linux/pci_regs.h>
14#include <linux/types.h>
15
16/**
17 * pci_vc_save_restore_dwords - Save or restore a series of dwords
18 * @dev: device
19 * @pos: starting config space position
20 * @buf: buffer to save to or restore from
21 * @dwords: number of dwords to save/restore
22 * @save: whether to save or restore
23 */
24static void pci_vc_save_restore_dwords(struct pci_dev *dev, int pos,
25 u32 *buf, int dwords, bool save)
26{
27 int i;
28
29 for (i = 0; i < dwords; i++, buf++) {
30 if (save)
31 pci_read_config_dword(dev, pos + (i * 4), buf);
32 else
33 pci_write_config_dword(dev, pos + (i * 4), *buf);
34 }
35}
36
37/**
38 * pci_vc_load_arb_table - load and wait for VC arbitration table
39 * @dev: device
40 * @pos: starting position of VC capability (VC/VC9/MFVC)
41 *
42 * Set Load VC Arbitration Table bit requesting hardware to apply the VC
43 * Arbitration Table (previously loaded). When the VC Arbitration Table
44 * Status clears, hardware has latched the table into VC arbitration logic.
45 */
46static void pci_vc_load_arb_table(struct pci_dev *dev, int pos)
47{
48 u16 ctrl;
49
50 pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL, &ctrl);
51 pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL,
52 ctrl | PCI_VC_PORT_CTRL_LOAD_TABLE);
53 if (pci_wait_for_pending(dev, pos + PCI_VC_PORT_STATUS,
54 PCI_VC_PORT_STATUS_TABLE))
55 return;
56
57 pci_err(dev, "VC arbitration table failed to load\n");
58}
59
60/**
61 * pci_vc_load_port_arb_table - Load and wait for VC port arbitration table
62 * @dev: device
63 * @pos: starting position of VC capability (VC/VC9/MFVC)
64 * @res: VC resource number, ie. VCn (0-7)
65 *
66 * Set Load Port Arbitration Table bit requesting hardware to apply the Port
67 * Arbitration Table (previously loaded). When the Port Arbitration Table
68 * Status clears, hardware has latched the table into port arbitration logic.
69 */
70static void pci_vc_load_port_arb_table(struct pci_dev *dev, int pos, int res)
71{
72 int ctrl_pos, status_pos;
73 u32 ctrl;
74
75 ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF);
76 status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF);
77
78 pci_read_config_dword(dev, ctrl_pos, &ctrl);
79 pci_write_config_dword(dev, ctrl_pos,
80 ctrl | PCI_VC_RES_CTRL_LOAD_TABLE);
81
82 if (pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_TABLE))
83 return;
84
85 pci_err(dev, "VC%d port arbitration table failed to load\n", res);
86}
87
88/**
89 * pci_vc_enable - Enable virtual channel
90 * @dev: device
91 * @pos: starting position of VC capability (VC/VC9/MFVC)
92 * @res: VC res number, ie. VCn (0-7)
93 *
94 * A VC is enabled by setting the enable bit in matching resource control
95 * registers on both sides of a link. We therefore need to find the opposite
96 * end of the link. To keep this simple we enable from the downstream device.
97 * RC devices do not have an upstream device, nor does it seem that VC9 do
98 * (spec is unclear). Once we find the upstream device, match the VC ID to
99 * get the correct resource, disable and enable on both ends.
100 */
101static void pci_vc_enable(struct pci_dev *dev, int pos, int res)
102{
103 int ctrl_pos, status_pos, id, pos2, evcc, i, ctrl_pos2, status_pos2;
104 u32 ctrl, header, cap1, ctrl2;
105 struct pci_dev *link = NULL;
106
107 /* Enable VCs from the downstream device */
108 if (!dev->has_secondary_link)
109 return;
110
111 ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF);
112 status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF);
113
114 pci_read_config_dword(dev, ctrl_pos, &ctrl);
115 id = ctrl & PCI_VC_RES_CTRL_ID;
116
117 pci_read_config_dword(dev, pos, &header);
118
119 /* If there is no opposite end of the link, skip to enable */
120 if (PCI_EXT_CAP_ID(header) == PCI_EXT_CAP_ID_VC9 ||
121 pci_is_root_bus(dev->bus))
122 goto enable;
123
124 pos2 = pci_find_ext_capability(dev->bus->self, PCI_EXT_CAP_ID_VC);
125 if (!pos2)
126 goto enable;
127
128 pci_read_config_dword(dev->bus->self, pos2 + PCI_VC_PORT_CAP1, &cap1);
129 evcc = cap1 & PCI_VC_CAP1_EVCC;
130
131 /* VC0 is hardwired enabled, so we can start with 1 */
132 for (i = 1; i < evcc + 1; i++) {
133 ctrl_pos2 = pos2 + PCI_VC_RES_CTRL +
134 (i * PCI_CAP_VC_PER_VC_SIZEOF);
135 status_pos2 = pos2 + PCI_VC_RES_STATUS +
136 (i * PCI_CAP_VC_PER_VC_SIZEOF);
137 pci_read_config_dword(dev->bus->self, ctrl_pos2, &ctrl2);
138 if ((ctrl2 & PCI_VC_RES_CTRL_ID) == id) {
139 link = dev->bus->self;
140 break;
141 }
142 }
143
144 if (!link)
145 goto enable;
146
147 /* Disable if enabled */
148 if (ctrl2 & PCI_VC_RES_CTRL_ENABLE) {
149 ctrl2 &= ~PCI_VC_RES_CTRL_ENABLE;
150 pci_write_config_dword(link, ctrl_pos2, ctrl2);
151 }
152
153 /* Enable on both ends */
154 ctrl2 |= PCI_VC_RES_CTRL_ENABLE;
155 pci_write_config_dword(link, ctrl_pos2, ctrl2);
156enable:
157 ctrl |= PCI_VC_RES_CTRL_ENABLE;
158 pci_write_config_dword(dev, ctrl_pos, ctrl);
159
160 if (!pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_NEGO))
161 pci_err(dev, "VC%d negotiation stuck pending\n", id);
162
163 if (link && !pci_wait_for_pending(link, status_pos2,
164 PCI_VC_RES_STATUS_NEGO))
165 pci_err(link, "VC%d negotiation stuck pending\n", id);
166}
167
168/**
169 * pci_vc_do_save_buffer - Size, save, or restore VC state
170 * @dev: device
171 * @pos: starting position of VC capability (VC/VC9/MFVC)
172 * @save_state: buffer for save/restore
173 * @name: for error message
174 * @save: if provided a buffer, this indicates what to do with it
175 *
176 * Walking Virtual Channel config space to size, save, or restore it
177 * is complicated, so we do it all from one function to reduce code and
178 * guarantee ordering matches in the buffer. When called with NULL
179 * @save_state, return the size of the necessary save buffer. When called
180 * with a non-NULL @save_state, @save determines whether we save to the
181 * buffer or restore from it.
182 */
183static int pci_vc_do_save_buffer(struct pci_dev *dev, int pos,
184 struct pci_cap_saved_state *save_state,
185 bool save)
186{
187 u32 cap1;
188 char evcc, lpevcc, parb_size;
189 int i, len = 0;
190 u8 *buf = save_state ? (u8 *)save_state->cap.data : NULL;
191
192 /* Sanity check buffer size for save/restore */
193 if (buf && save_state->cap.size !=
194 pci_vc_do_save_buffer(dev, pos, NULL, save)) {
195 pci_err(dev, "VC save buffer size does not match @0x%x\n", pos);
196 return -ENOMEM;
197 }
198
199 pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP1, &cap1);
200 /* Extended VC Count (not counting VC0) */
201 evcc = cap1 & PCI_VC_CAP1_EVCC;
202 /* Low Priority Extended VC Count (not counting VC0) */
203 lpevcc = (cap1 & PCI_VC_CAP1_LPEVCC) >> 4;
204 /* Port Arbitration Table Entry Size (bits) */
205 parb_size = 1 << ((cap1 & PCI_VC_CAP1_ARB_SIZE) >> 10);
206
207 /*
208 * Port VC Control Register contains VC Arbitration Select, which
209 * cannot be modified when more than one LPVC is in operation. We
210 * therefore save/restore it first, as only VC0 should be enabled
211 * after device reset.
212 */
213 if (buf) {
214 if (save)
215 pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL,
216 (u16 *)buf);
217 else
218 pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL,
219 *(u16 *)buf);
220 buf += 4;
221 }
222 len += 4;
223
224 /*
225 * If we have any Low Priority VCs and a VC Arbitration Table Offset
226 * in Port VC Capability Register 2 then save/restore it next.
227 */
228 if (lpevcc) {
229 u32 cap2;
230 int vcarb_offset;
231
232 pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP2, &cap2);
233 vcarb_offset = ((cap2 & PCI_VC_CAP2_ARB_OFF) >> 24) * 16;
234
235 if (vcarb_offset) {
236 int size, vcarb_phases = 0;
237
238 if (cap2 & PCI_VC_CAP2_128_PHASE)
239 vcarb_phases = 128;
240 else if (cap2 & PCI_VC_CAP2_64_PHASE)
241 vcarb_phases = 64;
242 else if (cap2 & PCI_VC_CAP2_32_PHASE)
243 vcarb_phases = 32;
244
245 /* Fixed 4 bits per phase per lpevcc (plus VC0) */
246 size = ((lpevcc + 1) * vcarb_phases * 4) / 8;
247
248 if (size && buf) {
249 pci_vc_save_restore_dwords(dev,
250 pos + vcarb_offset,
251 (u32 *)buf,
252 size / 4, save);
253 /*
254 * On restore, we need to signal hardware to
255 * re-load the VC Arbitration Table.
256 */
257 if (!save)
258 pci_vc_load_arb_table(dev, pos);
259
260 buf += size;
261 }
262 len += size;
263 }
264 }
265
266 /*
267 * In addition to each VC Resource Control Register, we may have a
268 * Port Arbitration Table attached to each VC. The Port Arbitration
269 * Table Offset in each VC Resource Capability Register tells us if
270 * it exists. The entry size is global from the Port VC Capability
271 * Register1 above. The number of phases is determined per VC.
272 */
273 for (i = 0; i < evcc + 1; i++) {
274 u32 cap;
275 int parb_offset;
276
277 pci_read_config_dword(dev, pos + PCI_VC_RES_CAP +
278 (i * PCI_CAP_VC_PER_VC_SIZEOF), &cap);
279 parb_offset = ((cap & PCI_VC_RES_CAP_ARB_OFF) >> 24) * 16;
280 if (parb_offset) {
281 int size, parb_phases = 0;
282
283 if (cap & PCI_VC_RES_CAP_256_PHASE)
284 parb_phases = 256;
285 else if (cap & (PCI_VC_RES_CAP_128_PHASE |
286 PCI_VC_RES_CAP_128_PHASE_TB))
287 parb_phases = 128;
288 else if (cap & PCI_VC_RES_CAP_64_PHASE)
289 parb_phases = 64;
290 else if (cap & PCI_VC_RES_CAP_32_PHASE)
291 parb_phases = 32;
292
293 size = (parb_size * parb_phases) / 8;
294
295 if (size && buf) {
296 pci_vc_save_restore_dwords(dev,
297 pos + parb_offset,
298 (u32 *)buf,
299 size / 4, save);
300 buf += size;
301 }
302 len += size;
303 }
304
305 /* VC Resource Control Register */
306 if (buf) {
307 int ctrl_pos = pos + PCI_VC_RES_CTRL +
308 (i * PCI_CAP_VC_PER_VC_SIZEOF);
309 if (save)
310 pci_read_config_dword(dev, ctrl_pos,
311 (u32 *)buf);
312 else {
313 u32 tmp, ctrl = *(u32 *)buf;
314 /*
315 * For an FLR case, the VC config may remain.
316 * Preserve enable bit, restore the rest.
317 */
318 pci_read_config_dword(dev, ctrl_pos, &tmp);
319 tmp &= PCI_VC_RES_CTRL_ENABLE;
320 tmp |= ctrl & ~PCI_VC_RES_CTRL_ENABLE;
321 pci_write_config_dword(dev, ctrl_pos, tmp);
322 /* Load port arbitration table if used */
323 if (ctrl & PCI_VC_RES_CTRL_ARB_SELECT)
324 pci_vc_load_port_arb_table(dev, pos, i);
325 /* Re-enable if needed */
326 if ((ctrl ^ tmp) & PCI_VC_RES_CTRL_ENABLE)
327 pci_vc_enable(dev, pos, i);
328 }
329 buf += 4;
330 }
331 len += 4;
332 }
333
334 return buf ? 0 : len;
335}
336
337static struct {
338 u16 id;
339 const char *name;
340} vc_caps[] = { { PCI_EXT_CAP_ID_MFVC, "MFVC" },
341 { PCI_EXT_CAP_ID_VC, "VC" },
342 { PCI_EXT_CAP_ID_VC9, "VC9" } };
343
344/**
345 * pci_save_vc_state - Save VC state to pre-allocate save buffer
346 * @dev: device
347 *
348 * For each type of VC capability, VC/VC9/MFVC, find the capability and
349 * save it to the pre-allocated save buffer.
350 */
351int pci_save_vc_state(struct pci_dev *dev)
352{
353 int i;
354
355 for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
356 int pos, ret;
357 struct pci_cap_saved_state *save_state;
358
359 pos = pci_find_ext_capability(dev, vc_caps[i].id);
360 if (!pos)
361 continue;
362
363 save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
364 if (!save_state) {
365 pci_err(dev, "%s buffer not found in %s\n",
366 vc_caps[i].name, __func__);
367 return -ENOMEM;
368 }
369
370 ret = pci_vc_do_save_buffer(dev, pos, save_state, true);
371 if (ret) {
372 pci_err(dev, "%s save unsuccessful %s\n",
373 vc_caps[i].name, __func__);
374 return ret;
375 }
376 }
377
378 return 0;
379}
380
381/**
382 * pci_restore_vc_state - Restore VC state from save buffer
383 * @dev: device
384 *
385 * For each type of VC capability, VC/VC9/MFVC, find the capability and
386 * restore it from the previously saved buffer.
387 */
388void pci_restore_vc_state(struct pci_dev *dev)
389{
390 int i;
391
392 for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
393 int pos;
394 struct pci_cap_saved_state *save_state;
395
396 pos = pci_find_ext_capability(dev, vc_caps[i].id);
397 save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
398 if (!save_state || !pos)
399 continue;
400
401 pci_vc_do_save_buffer(dev, pos, save_state, false);
402 }
403}
404
405/**
406 * pci_allocate_vc_save_buffers - Allocate save buffers for VC caps
407 * @dev: device
408 *
409 * For each type of VC capability, VC/VC9/MFVC, find the capability, size
410 * it, and allocate a buffer for save/restore.
411 */
412
413void pci_allocate_vc_save_buffers(struct pci_dev *dev)
414{
415 int i;
416
417 for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
418 int len, pos = pci_find_ext_capability(dev, vc_caps[i].id);
419
420 if (!pos)
421 continue;
422
423 len = pci_vc_do_save_buffer(dev, pos, NULL, false);
424 if (pci_add_ext_cap_save_buffer(dev, vc_caps[i].id, len))
425 pci_err(dev, "unable to preallocate %s save buffer\n",
426 vc_caps[i].name);
427 }
428}