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1/*
2 * PCI Virtual Channel support
3 *
4 * Copyright (C) 2013 Red Hat, Inc. All rights reserved.
5 * Author: Alex Williamson <alex.williamson@redhat.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/device.h>
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/pci.h>
16#include <linux/pci_regs.h>
17#include <linux/types.h>
18
19/**
20 * pci_vc_save_restore_dwords - Save or restore a series of dwords
21 * @dev: device
22 * @pos: starting config space position
23 * @buf: buffer to save to or restore from
24 * @dwords: number of dwords to save/restore
25 * @save: whether to save or restore
26 */
27static void pci_vc_save_restore_dwords(struct pci_dev *dev, int pos,
28 u32 *buf, int dwords, bool save)
29{
30 int i;
31
32 for (i = 0; i < dwords; i++, buf++) {
33 if (save)
34 pci_read_config_dword(dev, pos + (i * 4), buf);
35 else
36 pci_write_config_dword(dev, pos + (i * 4), *buf);
37 }
38}
39
40/**
41 * pci_vc_load_arb_table - load and wait for VC arbitration table
42 * @dev: device
43 * @pos: starting position of VC capability (VC/VC9/MFVC)
44 *
45 * Set Load VC Arbitration Table bit requesting hardware to apply the VC
46 * Arbitration Table (previously loaded). When the VC Arbitration Table
47 * Status clears, hardware has latched the table into VC arbitration logic.
48 */
49static void pci_vc_load_arb_table(struct pci_dev *dev, int pos)
50{
51 u16 ctrl;
52
53 pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL, &ctrl);
54 pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL,
55 ctrl | PCI_VC_PORT_CTRL_LOAD_TABLE);
56 if (pci_wait_for_pending(dev, pos + PCI_VC_PORT_STATUS,
57 PCI_VC_PORT_STATUS_TABLE))
58 return;
59
60 dev_err(&dev->dev, "VC arbitration table failed to load\n");
61}
62
63/**
64 * pci_vc_load_port_arb_table - Load and wait for VC port arbitration table
65 * @dev: device
66 * @pos: starting position of VC capability (VC/VC9/MFVC)
67 * @res: VC resource number, ie. VCn (0-7)
68 *
69 * Set Load Port Arbitration Table bit requesting hardware to apply the Port
70 * Arbitration Table (previously loaded). When the Port Arbitration Table
71 * Status clears, hardware has latched the table into port arbitration logic.
72 */
73static void pci_vc_load_port_arb_table(struct pci_dev *dev, int pos, int res)
74{
75 int ctrl_pos, status_pos;
76 u32 ctrl;
77
78 ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF);
79 status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF);
80
81 pci_read_config_dword(dev, ctrl_pos, &ctrl);
82 pci_write_config_dword(dev, ctrl_pos,
83 ctrl | PCI_VC_RES_CTRL_LOAD_TABLE);
84
85 if (pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_TABLE))
86 return;
87
88 dev_err(&dev->dev, "VC%d port arbitration table failed to load\n", res);
89}
90
91/**
92 * pci_vc_enable - Enable virtual channel
93 * @dev: device
94 * @pos: starting position of VC capability (VC/VC9/MFVC)
95 * @res: VC res number, ie. VCn (0-7)
96 *
97 * A VC is enabled by setting the enable bit in matching resource control
98 * registers on both sides of a link. We therefore need to find the opposite
99 * end of the link. To keep this simple we enable from the downstream device.
100 * RC devices do not have an upstream device, nor does it seem that VC9 do
101 * (spec is unclear). Once we find the upstream device, match the VC ID to
102 * get the correct resource, disable and enable on both ends.
103 */
104static void pci_vc_enable(struct pci_dev *dev, int pos, int res)
105{
106 int ctrl_pos, status_pos, id, pos2, evcc, i, ctrl_pos2, status_pos2;
107 u32 ctrl, header, cap1, ctrl2;
108 struct pci_dev *link = NULL;
109
110 /* Enable VCs from the downstream device */
111 if (!dev->has_secondary_link)
112 return;
113
114 ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF);
115 status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF);
116
117 pci_read_config_dword(dev, ctrl_pos, &ctrl);
118 id = ctrl & PCI_VC_RES_CTRL_ID;
119
120 pci_read_config_dword(dev, pos, &header);
121
122 /* If there is no opposite end of the link, skip to enable */
123 if (PCI_EXT_CAP_ID(header) == PCI_EXT_CAP_ID_VC9 ||
124 pci_is_root_bus(dev->bus))
125 goto enable;
126
127 pos2 = pci_find_ext_capability(dev->bus->self, PCI_EXT_CAP_ID_VC);
128 if (!pos2)
129 goto enable;
130
131 pci_read_config_dword(dev->bus->self, pos2 + PCI_VC_PORT_CAP1, &cap1);
132 evcc = cap1 & PCI_VC_CAP1_EVCC;
133
134 /* VC0 is hardwired enabled, so we can start with 1 */
135 for (i = 1; i < evcc + 1; i++) {
136 ctrl_pos2 = pos2 + PCI_VC_RES_CTRL +
137 (i * PCI_CAP_VC_PER_VC_SIZEOF);
138 status_pos2 = pos2 + PCI_VC_RES_STATUS +
139 (i * PCI_CAP_VC_PER_VC_SIZEOF);
140 pci_read_config_dword(dev->bus->self, ctrl_pos2, &ctrl2);
141 if ((ctrl2 & PCI_VC_RES_CTRL_ID) == id) {
142 link = dev->bus->self;
143 break;
144 }
145 }
146
147 if (!link)
148 goto enable;
149
150 /* Disable if enabled */
151 if (ctrl2 & PCI_VC_RES_CTRL_ENABLE) {
152 ctrl2 &= ~PCI_VC_RES_CTRL_ENABLE;
153 pci_write_config_dword(link, ctrl_pos2, ctrl2);
154 }
155
156 /* Enable on both ends */
157 ctrl2 |= PCI_VC_RES_CTRL_ENABLE;
158 pci_write_config_dword(link, ctrl_pos2, ctrl2);
159enable:
160 ctrl |= PCI_VC_RES_CTRL_ENABLE;
161 pci_write_config_dword(dev, ctrl_pos, ctrl);
162
163 if (!pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_NEGO))
164 dev_err(&dev->dev, "VC%d negotiation stuck pending\n", id);
165
166 if (link && !pci_wait_for_pending(link, status_pos2,
167 PCI_VC_RES_STATUS_NEGO))
168 dev_err(&link->dev, "VC%d negotiation stuck pending\n", id);
169}
170
171/**
172 * pci_vc_do_save_buffer - Size, save, or restore VC state
173 * @dev: device
174 * @pos: starting position of VC capability (VC/VC9/MFVC)
175 * @save_state: buffer for save/restore
176 * @name: for error message
177 * @save: if provided a buffer, this indicates what to do with it
178 *
179 * Walking Virtual Channel config space to size, save, or restore it
180 * is complicated, so we do it all from one function to reduce code and
181 * guarantee ordering matches in the buffer. When called with NULL
182 * @save_state, return the size of the necessary save buffer. When called
183 * with a non-NULL @save_state, @save determines whether we save to the
184 * buffer or restore from it.
185 */
186static int pci_vc_do_save_buffer(struct pci_dev *dev, int pos,
187 struct pci_cap_saved_state *save_state,
188 bool save)
189{
190 u32 cap1;
191 char evcc, lpevcc, parb_size;
192 int i, len = 0;
193 u8 *buf = save_state ? (u8 *)save_state->cap.data : NULL;
194
195 /* Sanity check buffer size for save/restore */
196 if (buf && save_state->cap.size !=
197 pci_vc_do_save_buffer(dev, pos, NULL, save)) {
198 dev_err(&dev->dev,
199 "VC save buffer size does not match @0x%x\n", pos);
200 return -ENOMEM;
201 }
202
203 pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP1, &cap1);
204 /* Extended VC Count (not counting VC0) */
205 evcc = cap1 & PCI_VC_CAP1_EVCC;
206 /* Low Priority Extended VC Count (not counting VC0) */
207 lpevcc = (cap1 & PCI_VC_CAP1_LPEVCC) >> 4;
208 /* Port Arbitration Table Entry Size (bits) */
209 parb_size = 1 << ((cap1 & PCI_VC_CAP1_ARB_SIZE) >> 10);
210
211 /*
212 * Port VC Control Register contains VC Arbitration Select, which
213 * cannot be modified when more than one LPVC is in operation. We
214 * therefore save/restore it first, as only VC0 should be enabled
215 * after device reset.
216 */
217 if (buf) {
218 if (save)
219 pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL,
220 (u16 *)buf);
221 else
222 pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL,
223 *(u16 *)buf);
224 buf += 2;
225 }
226 len += 2;
227
228 /*
229 * If we have any Low Priority VCs and a VC Arbitration Table Offset
230 * in Port VC Capability Register 2 then save/restore it next.
231 */
232 if (lpevcc) {
233 u32 cap2;
234 int vcarb_offset;
235
236 pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP2, &cap2);
237 vcarb_offset = ((cap2 & PCI_VC_CAP2_ARB_OFF) >> 24) * 16;
238
239 if (vcarb_offset) {
240 int size, vcarb_phases = 0;
241
242 if (cap2 & PCI_VC_CAP2_128_PHASE)
243 vcarb_phases = 128;
244 else if (cap2 & PCI_VC_CAP2_64_PHASE)
245 vcarb_phases = 64;
246 else if (cap2 & PCI_VC_CAP2_32_PHASE)
247 vcarb_phases = 32;
248
249 /* Fixed 4 bits per phase per lpevcc (plus VC0) */
250 size = ((lpevcc + 1) * vcarb_phases * 4) / 8;
251
252 if (size && buf) {
253 pci_vc_save_restore_dwords(dev,
254 pos + vcarb_offset,
255 (u32 *)buf,
256 size / 4, save);
257 /*
258 * On restore, we need to signal hardware to
259 * re-load the VC Arbitration Table.
260 */
261 if (!save)
262 pci_vc_load_arb_table(dev, pos);
263
264 buf += size;
265 }
266 len += size;
267 }
268 }
269
270 /*
271 * In addition to each VC Resource Control Register, we may have a
272 * Port Arbitration Table attached to each VC. The Port Arbitration
273 * Table Offset in each VC Resource Capability Register tells us if
274 * it exists. The entry size is global from the Port VC Capability
275 * Register1 above. The number of phases is determined per VC.
276 */
277 for (i = 0; i < evcc + 1; i++) {
278 u32 cap;
279 int parb_offset;
280
281 pci_read_config_dword(dev, pos + PCI_VC_RES_CAP +
282 (i * PCI_CAP_VC_PER_VC_SIZEOF), &cap);
283 parb_offset = ((cap & PCI_VC_RES_CAP_ARB_OFF) >> 24) * 16;
284 if (parb_offset) {
285 int size, parb_phases = 0;
286
287 if (cap & PCI_VC_RES_CAP_256_PHASE)
288 parb_phases = 256;
289 else if (cap & (PCI_VC_RES_CAP_128_PHASE |
290 PCI_VC_RES_CAP_128_PHASE_TB))
291 parb_phases = 128;
292 else if (cap & PCI_VC_RES_CAP_64_PHASE)
293 parb_phases = 64;
294 else if (cap & PCI_VC_RES_CAP_32_PHASE)
295 parb_phases = 32;
296
297 size = (parb_size * parb_phases) / 8;
298
299 if (size && buf) {
300 pci_vc_save_restore_dwords(dev,
301 pos + parb_offset,
302 (u32 *)buf,
303 size / 4, save);
304 buf += size;
305 }
306 len += size;
307 }
308
309 /* VC Resource Control Register */
310 if (buf) {
311 int ctrl_pos = pos + PCI_VC_RES_CTRL +
312 (i * PCI_CAP_VC_PER_VC_SIZEOF);
313 if (save)
314 pci_read_config_dword(dev, ctrl_pos,
315 (u32 *)buf);
316 else {
317 u32 tmp, ctrl = *(u32 *)buf;
318 /*
319 * For an FLR case, the VC config may remain.
320 * Preserve enable bit, restore the rest.
321 */
322 pci_read_config_dword(dev, ctrl_pos, &tmp);
323 tmp &= PCI_VC_RES_CTRL_ENABLE;
324 tmp |= ctrl & ~PCI_VC_RES_CTRL_ENABLE;
325 pci_write_config_dword(dev, ctrl_pos, tmp);
326 /* Load port arbitration table if used */
327 if (ctrl & PCI_VC_RES_CTRL_ARB_SELECT)
328 pci_vc_load_port_arb_table(dev, pos, i);
329 /* Re-enable if needed */
330 if ((ctrl ^ tmp) & PCI_VC_RES_CTRL_ENABLE)
331 pci_vc_enable(dev, pos, i);
332 }
333 buf += 4;
334 }
335 len += 4;
336 }
337
338 return buf ? 0 : len;
339}
340
341static struct {
342 u16 id;
343 const char *name;
344} vc_caps[] = { { PCI_EXT_CAP_ID_MFVC, "MFVC" },
345 { PCI_EXT_CAP_ID_VC, "VC" },
346 { PCI_EXT_CAP_ID_VC9, "VC9" } };
347
348/**
349 * pci_save_vc_state - Save VC state to pre-allocate save buffer
350 * @dev: device
351 *
352 * For each type of VC capability, VC/VC9/MFVC, find the capability and
353 * save it to the pre-allocated save buffer.
354 */
355int pci_save_vc_state(struct pci_dev *dev)
356{
357 int i;
358
359 for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
360 int pos, ret;
361 struct pci_cap_saved_state *save_state;
362
363 pos = pci_find_ext_capability(dev, vc_caps[i].id);
364 if (!pos)
365 continue;
366
367 save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
368 if (!save_state) {
369 dev_err(&dev->dev, "%s buffer not found in %s\n",
370 vc_caps[i].name, __func__);
371 return -ENOMEM;
372 }
373
374 ret = pci_vc_do_save_buffer(dev, pos, save_state, true);
375 if (ret) {
376 dev_err(&dev->dev, "%s save unsuccessful %s\n",
377 vc_caps[i].name, __func__);
378 return ret;
379 }
380 }
381
382 return 0;
383}
384
385/**
386 * pci_restore_vc_state - Restore VC state from save buffer
387 * @dev: device
388 *
389 * For each type of VC capability, VC/VC9/MFVC, find the capability and
390 * restore it from the previously saved buffer.
391 */
392void pci_restore_vc_state(struct pci_dev *dev)
393{
394 int i;
395
396 for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
397 int pos;
398 struct pci_cap_saved_state *save_state;
399
400 pos = pci_find_ext_capability(dev, vc_caps[i].id);
401 save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
402 if (!save_state || !pos)
403 continue;
404
405 pci_vc_do_save_buffer(dev, pos, save_state, false);
406 }
407}
408
409/**
410 * pci_allocate_vc_save_buffers - Allocate save buffers for VC caps
411 * @dev: device
412 *
413 * For each type of VC capability, VC/VC9/MFVC, find the capability, size
414 * it, and allocate a buffer for save/restore.
415 */
416
417void pci_allocate_vc_save_buffers(struct pci_dev *dev)
418{
419 int i;
420
421 for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
422 int len, pos = pci_find_ext_capability(dev, vc_caps[i].id);
423
424 if (!pos)
425 continue;
426
427 len = pci_vc_do_save_buffer(dev, pos, NULL, false);
428 if (pci_add_ext_cap_save_buffer(dev, vc_caps[i].id, len))
429 dev_err(&dev->dev,
430 "unable to preallocate %s save buffer\n",
431 vc_caps[i].name);
432 }
433}