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1 /*
2 * Copyright (C) 2014 Linaro Ltd.
3 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * PCC (Platform Communication Channel) is defined in the ACPI 5.0+
16 * specification. It is a mailbox like mechanism to allow clients
17 * such as CPPC (Collaborative Processor Performance Control), RAS
18 * (Reliability, Availability and Serviceability) and MPST (Memory
19 * Node Power State Table) to talk to the platform (e.g. BMC) through
20 * shared memory regions as defined in the PCC table entries. The PCC
21 * specification supports a Doorbell mechanism for the PCC clients
22 * to notify the platform about new data. This Doorbell information
23 * is also specified in each PCC table entry.
24 *
25 * Typical high level flow of operation is:
26 *
27 * PCC Reads:
28 * * Client tries to acquire a channel lock.
29 * * After it is acquired it writes READ cmd in communication region cmd
30 * address.
31 * * Client issues mbox_send_message() which rings the PCC doorbell
32 * for its PCC channel.
33 * * If command completes, then client has control over channel and
34 * it can proceed with its reads.
35 * * Client releases lock.
36 *
37 * PCC Writes:
38 * * Client tries to acquire channel lock.
39 * * Client writes to its communication region after it acquires a
40 * channel lock.
41 * * Client writes WRITE cmd in communication region cmd address.
42 * * Client issues mbox_send_message() which rings the PCC doorbell
43 * for its PCC channel.
44 * * If command completes, then writes have succeded and it can release
45 * the channel lock.
46 *
47 * There is a Nominal latency defined for each channel which indicates
48 * how long to wait until a command completes. If command is not complete
49 * the client needs to retry or assume failure.
50 *
51 * For more details about PCC, please see the ACPI specification from
52 * http://www.uefi.org/ACPIv5.1 Section 14.
53 *
54 * This file implements PCC as a Mailbox controller and allows for PCC
55 * clients to be implemented as its Mailbox Client Channels.
56 */
57
58 #include <linux/acpi.h>
59 #include <linux/delay.h>
60 #include <linux/io.h>
61 #include <linux/init.h>
62 #include <linux/interrupt.h>
63 #include <linux/list.h>
64 #include <linux/platform_device.h>
65 #include <linux/mailbox_controller.h>
66 #include <linux/mailbox_client.h>
67 #include <linux/io-64-nonatomic-lo-hi.h>
68 #include <acpi/pcc.h>
69
70 #include "mailbox.h"
71
72 #define MAX_PCC_SUBSPACES 256
73 #define MBOX_IRQ_NAME "pcc-mbox"
74
75 static struct mbox_chan *pcc_mbox_channels;
76
77 /* Array of cached virtual address for doorbell registers */
78 static void __iomem **pcc_doorbell_vaddr;
79 /* Array of cached virtual address for doorbell ack registers */
80 static void __iomem **pcc_doorbell_ack_vaddr;
81 /* Array of doorbell interrupts */
82 static int *pcc_doorbell_irq;
83
84 static struct mbox_controller pcc_mbox_ctrl = {};
85 /**
86 * get_pcc_channel - Given a PCC subspace idx, get
87 * the respective mbox_channel.
88 * @id: PCC subspace index.
89 *
90 * Return: ERR_PTR(errno) if error, else pointer
91 * to mbox channel.
92 */
93 static struct mbox_chan *get_pcc_channel(int id)
94 {
95 if (id < 0 || id > pcc_mbox_ctrl.num_chans)
96 return ERR_PTR(-ENOENT);
97
98 return &pcc_mbox_channels[id];
99 }
100
101 /*
102 * PCC can be used with perf critical drivers such as CPPC
103 * So it makes sense to locally cache the virtual address and
104 * use it to read/write to PCC registers such as doorbell register
105 *
106 * The below read_register and write_registers are used to read and
107 * write from perf critical registers such as PCC doorbell register
108 */
109 static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
110 {
111 int ret_val = 0;
112
113 switch (bit_width) {
114 case 8:
115 *val = readb(vaddr);
116 break;
117 case 16:
118 *val = readw(vaddr);
119 break;
120 case 32:
121 *val = readl(vaddr);
122 break;
123 case 64:
124 *val = readq(vaddr);
125 break;
126 default:
127 pr_debug("Error: Cannot read register of %u bit width",
128 bit_width);
129 ret_val = -EFAULT;
130 break;
131 }
132 return ret_val;
133 }
134
135 static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
136 {
137 int ret_val = 0;
138
139 switch (bit_width) {
140 case 8:
141 writeb(val, vaddr);
142 break;
143 case 16:
144 writew(val, vaddr);
145 break;
146 case 32:
147 writel(val, vaddr);
148 break;
149 case 64:
150 writeq(val, vaddr);
151 break;
152 default:
153 pr_debug("Error: Cannot write register of %u bit width",
154 bit_width);
155 ret_val = -EFAULT;
156 break;
157 }
158 return ret_val;
159 }
160
161 /**
162 * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number
163 * @interrupt: GSI number.
164 * @flags: interrupt flags
165 *
166 * Returns: a valid linux IRQ number on success
167 * 0 or -EINVAL on failure
168 */
169 static int pcc_map_interrupt(u32 interrupt, u32 flags)
170 {
171 int trigger, polarity;
172
173 if (!interrupt)
174 return 0;
175
176 trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
177 : ACPI_LEVEL_SENSITIVE;
178
179 polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
180 : ACPI_ACTIVE_HIGH;
181
182 return acpi_register_gsi(NULL, interrupt, trigger, polarity);
183 }
184
185 /**
186 * pcc_mbox_irq - PCC mailbox interrupt handler
187 */
188 static irqreturn_t pcc_mbox_irq(int irq, void *p)
189 {
190 struct acpi_generic_address *doorbell_ack;
191 struct acpi_pcct_hw_reduced *pcct_ss;
192 struct mbox_chan *chan = p;
193 u64 doorbell_ack_preserve;
194 u64 doorbell_ack_write;
195 u64 doorbell_ack_val;
196 int ret;
197
198 pcct_ss = chan->con_priv;
199
200 mbox_chan_received_data(chan, NULL);
201
202 if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
203 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = chan->con_priv;
204 u32 id = chan - pcc_mbox_channels;
205
206 doorbell_ack = &pcct2_ss->doorbell_ack_register;
207 doorbell_ack_preserve = pcct2_ss->ack_preserve_mask;
208 doorbell_ack_write = pcct2_ss->ack_write_mask;
209
210 ret = read_register(pcc_doorbell_ack_vaddr[id],
211 &doorbell_ack_val,
212 doorbell_ack->bit_width);
213 if (ret)
214 return IRQ_NONE;
215
216 ret = write_register(pcc_doorbell_ack_vaddr[id],
217 (doorbell_ack_val & doorbell_ack_preserve)
218 | doorbell_ack_write,
219 doorbell_ack->bit_width);
220 if (ret)
221 return IRQ_NONE;
222 }
223
224 return IRQ_HANDLED;
225 }
226
227 /**
228 * pcc_mbox_request_channel - PCC clients call this function to
229 * request a pointer to their PCC subspace, from which they
230 * can get the details of communicating with the remote.
231 * @cl: Pointer to Mailbox client, so we know where to bind the
232 * Channel.
233 * @subspace_id: The PCC Subspace index as parsed in the PCC client
234 * ACPI package. This is used to lookup the array of PCC
235 * subspaces as parsed by the PCC Mailbox controller.
236 *
237 * Return: Pointer to the Mailbox Channel if successful or
238 * ERR_PTR.
239 */
240 struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
241 int subspace_id)
242 {
243 struct device *dev = pcc_mbox_ctrl.dev;
244 struct mbox_chan *chan;
245 unsigned long flags;
246
247 /*
248 * Each PCC Subspace is a Mailbox Channel.
249 * The PCC Clients get their PCC Subspace ID
250 * from their own tables and pass it here.
251 * This returns a pointer to the PCC subspace
252 * for the Client to operate on.
253 */
254 chan = get_pcc_channel(subspace_id);
255
256 if (IS_ERR(chan) || chan->cl) {
257 dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
258 return ERR_PTR(-EBUSY);
259 }
260
261 spin_lock_irqsave(&chan->lock, flags);
262 chan->msg_free = 0;
263 chan->msg_count = 0;
264 chan->active_req = NULL;
265 chan->cl = cl;
266 init_completion(&chan->tx_complete);
267
268 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
269 chan->txdone_method |= TXDONE_BY_ACK;
270
271 spin_unlock_irqrestore(&chan->lock, flags);
272
273 if (pcc_doorbell_irq[subspace_id] > 0) {
274 int rc;
275
276 rc = devm_request_irq(dev, pcc_doorbell_irq[subspace_id],
277 pcc_mbox_irq, 0, MBOX_IRQ_NAME, chan);
278 if (unlikely(rc)) {
279 dev_err(dev, "failed to register PCC interrupt %d\n",
280 pcc_doorbell_irq[subspace_id]);
281 pcc_mbox_free_channel(chan);
282 chan = ERR_PTR(rc);
283 }
284 }
285
286 return chan;
287 }
288 EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
289
290 /**
291 * pcc_mbox_free_channel - Clients call this to free their Channel.
292 *
293 * @chan: Pointer to the mailbox channel as returned by
294 * pcc_mbox_request_channel()
295 */
296 void pcc_mbox_free_channel(struct mbox_chan *chan)
297 {
298 u32 id = chan - pcc_mbox_channels;
299 unsigned long flags;
300
301 if (!chan || !chan->cl)
302 return;
303
304 if (id >= pcc_mbox_ctrl.num_chans) {
305 pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n");
306 return;
307 }
308
309 if (pcc_doorbell_irq[id] > 0)
310 devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan);
311
312 spin_lock_irqsave(&chan->lock, flags);
313 chan->cl = NULL;
314 chan->active_req = NULL;
315 if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
316 chan->txdone_method = TXDONE_BY_POLL;
317
318 spin_unlock_irqrestore(&chan->lock, flags);
319 }
320 EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
321
322 /**
323 * pcc_send_data - Called from Mailbox Controller code. Used
324 * here only to ring the channel doorbell. The PCC client
325 * specific read/write is done in the client driver in
326 * order to maintain atomicity over PCC channel once
327 * OS has control over it. See above for flow of operations.
328 * @chan: Pointer to Mailbox channel over which to send data.
329 * @data: Client specific data written over channel. Used here
330 * only for debug after PCC transaction completes.
331 *
332 * Return: Err if something failed else 0 for success.
333 */
334 static int pcc_send_data(struct mbox_chan *chan, void *data)
335 {
336 struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
337 struct acpi_generic_address *doorbell;
338 u64 doorbell_preserve;
339 u64 doorbell_val;
340 u64 doorbell_write;
341 u32 id = chan - pcc_mbox_channels;
342 int ret = 0;
343
344 if (id >= pcc_mbox_ctrl.num_chans) {
345 pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
346 return -ENOENT;
347 }
348
349 doorbell = &pcct_ss->doorbell_register;
350 doorbell_preserve = pcct_ss->preserve_mask;
351 doorbell_write = pcct_ss->write_mask;
352
353 /* Sync notification from OS to Platform. */
354 if (pcc_doorbell_vaddr[id]) {
355 ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
356 doorbell->bit_width);
357 if (ret)
358 return ret;
359 ret = write_register(pcc_doorbell_vaddr[id],
360 (doorbell_val & doorbell_preserve) | doorbell_write,
361 doorbell->bit_width);
362 } else {
363 ret = acpi_read(&doorbell_val, doorbell);
364 if (ret)
365 return ret;
366 ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
367 doorbell);
368 }
369 return ret;
370 }
371
372 static const struct mbox_chan_ops pcc_chan_ops = {
373 .send_data = pcc_send_data,
374 };
375
376 /**
377 * parse_pcc_subspace - Parse the PCC table and verify PCC subspace
378 * entries. There should be one entry per PCC client.
379 * @header: Pointer to the ACPI subtable header under the PCCT.
380 * @end: End of subtable entry.
381 *
382 * Return: 0 for Success, else errno.
383 *
384 * This gets called for each entry in the PCC table.
385 */
386 static int parse_pcc_subspace(struct acpi_subtable_header *header,
387 const unsigned long end)
388 {
389 struct acpi_pcct_hw_reduced *pcct_ss;
390
391 if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
392 pcct_ss = (struct acpi_pcct_hw_reduced *) header;
393
394 if ((pcct_ss->header.type !=
395 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE)
396 && (pcct_ss->header.type !=
397 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2)) {
398 pr_err("Incorrect PCC Subspace type detected\n");
399 return -EINVAL;
400 }
401 }
402
403 return 0;
404 }
405
406 /**
407 * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
408 * There should be one entry per PCC client.
409 * @id: PCC subspace index.
410 * @pcct_ss: Pointer to the ACPI subtable header under the PCCT.
411 *
412 * Return: 0 for Success, else errno.
413 *
414 * This gets called for each entry in the PCC table.
415 */
416 static int pcc_parse_subspace_irq(int id,
417 struct acpi_pcct_hw_reduced *pcct_ss)
418 {
419 pcc_doorbell_irq[id] = pcc_map_interrupt(pcct_ss->doorbell_interrupt,
420 (u32)pcct_ss->flags);
421 if (pcc_doorbell_irq[id] <= 0) {
422 pr_err("PCC GSI %d not registered\n",
423 pcct_ss->doorbell_interrupt);
424 return -EINVAL;
425 }
426
427 if (pcct_ss->header.type
428 == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
429 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
430
431 pcc_doorbell_ack_vaddr[id] = acpi_os_ioremap(
432 pcct2_ss->doorbell_ack_register.address,
433 pcct2_ss->doorbell_ack_register.bit_width / 8);
434 if (!pcc_doorbell_ack_vaddr[id]) {
435 pr_err("Failed to ioremap PCC ACK register\n");
436 return -ENOMEM;
437 }
438 }
439
440 return 0;
441 }
442
443 /**
444 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
445 *
446 * Return: 0 for Success, else errno.
447 */
448 static int __init acpi_pcc_probe(void)
449 {
450 acpi_size pcct_tbl_header_size;
451 struct acpi_table_header *pcct_tbl;
452 struct acpi_subtable_header *pcct_entry;
453 struct acpi_table_pcct *acpi_pcct_tbl;
454 int count, i, rc;
455 int sum = 0;
456 acpi_status status = AE_OK;
457
458 /* Search for PCCT */
459 status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,
460 &pcct_tbl,
461 &pcct_tbl_header_size);
462
463 if (ACPI_FAILURE(status) || !pcct_tbl) {
464 pr_warn("PCCT header not found.\n");
465 return -ENODEV;
466 }
467
468 count = acpi_table_parse_entries(ACPI_SIG_PCCT,
469 sizeof(struct acpi_table_pcct),
470 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
471 parse_pcc_subspace, MAX_PCC_SUBSPACES);
472 sum += (count > 0) ? count : 0;
473
474 count = acpi_table_parse_entries(ACPI_SIG_PCCT,
475 sizeof(struct acpi_table_pcct),
476 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2,
477 parse_pcc_subspace, MAX_PCC_SUBSPACES);
478 sum += (count > 0) ? count : 0;
479
480 if (sum == 0 || sum >= MAX_PCC_SUBSPACES) {
481 pr_err("Error parsing PCC subspaces from PCCT\n");
482 return -EINVAL;
483 }
484
485 pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
486 sum, GFP_KERNEL);
487 if (!pcc_mbox_channels) {
488 pr_err("Could not allocate space for PCC mbox channels\n");
489 return -ENOMEM;
490 }
491
492 pcc_doorbell_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
493 if (!pcc_doorbell_vaddr) {
494 rc = -ENOMEM;
495 goto err_free_mbox;
496 }
497
498 pcc_doorbell_ack_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
499 if (!pcc_doorbell_ack_vaddr) {
500 rc = -ENOMEM;
501 goto err_free_db_vaddr;
502 }
503
504 pcc_doorbell_irq = kcalloc(sum, sizeof(int), GFP_KERNEL);
505 if (!pcc_doorbell_irq) {
506 rc = -ENOMEM;
507 goto err_free_db_ack_vaddr;
508 }
509
510 /* Point to the first PCC subspace entry */
511 pcct_entry = (struct acpi_subtable_header *) (
512 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
513
514 acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
515 if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
516 pcc_mbox_ctrl.txdone_irq = true;
517
518 for (i = 0; i < sum; i++) {
519 struct acpi_generic_address *db_reg;
520 struct acpi_pcct_hw_reduced *pcct_ss;
521 pcc_mbox_channels[i].con_priv = pcct_entry;
522
523 pcct_ss = (struct acpi_pcct_hw_reduced *) pcct_entry;
524
525 if (pcc_mbox_ctrl.txdone_irq) {
526 rc = pcc_parse_subspace_irq(i, pcct_ss);
527 if (rc < 0)
528 goto err;
529 }
530
531 /* If doorbell is in system memory cache the virt address */
532 db_reg = &pcct_ss->doorbell_register;
533 if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
534 pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
535 db_reg->bit_width/8);
536 pcct_entry = (struct acpi_subtable_header *)
537 ((unsigned long) pcct_entry + pcct_entry->length);
538 }
539
540 pcc_mbox_ctrl.num_chans = sum;
541
542 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
543
544 return 0;
545
546 err:
547 kfree(pcc_doorbell_irq);
548 err_free_db_ack_vaddr:
549 kfree(pcc_doorbell_ack_vaddr);
550 err_free_db_vaddr:
551 kfree(pcc_doorbell_vaddr);
552 err_free_mbox:
553 kfree(pcc_mbox_channels);
554 return rc;
555 }
556
557 /**
558 * pcc_mbox_probe - Called when we find a match for the
559 * PCCT platform device. This is purely used to represent
560 * the PCCT as a virtual device for registering with the
561 * generic Mailbox framework.
562 *
563 * @pdev: Pointer to platform device returned when a match
564 * is found.
565 *
566 * Return: 0 for Success, else errno.
567 */
568 static int pcc_mbox_probe(struct platform_device *pdev)
569 {
570 int ret = 0;
571
572 pcc_mbox_ctrl.chans = pcc_mbox_channels;
573 pcc_mbox_ctrl.ops = &pcc_chan_ops;
574 pcc_mbox_ctrl.dev = &pdev->dev;
575
576 pr_info("Registering PCC driver as Mailbox controller\n");
577 ret = mbox_controller_register(&pcc_mbox_ctrl);
578
579 if (ret) {
580 pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
581 ret = -ENODEV;
582 }
583
584 return ret;
585 }
586
587 struct platform_driver pcc_mbox_driver = {
588 .probe = pcc_mbox_probe,
589 .driver = {
590 .name = "PCCT",
591 .owner = THIS_MODULE,
592 },
593 };
594
595 static int __init pcc_init(void)
596 {
597 int ret;
598 struct platform_device *pcc_pdev;
599
600 if (acpi_disabled)
601 return -ENODEV;
602
603 /* Check if PCC support is available. */
604 ret = acpi_pcc_probe();
605
606 if (ret) {
607 pr_debug("ACPI PCC probe failed.\n");
608 return -ENODEV;
609 }
610
611 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
612 pcc_mbox_probe, NULL, 0, NULL, 0);
613
614 if (IS_ERR(pcc_pdev)) {
615 pr_debug("Err creating PCC platform bundle\n");
616 return PTR_ERR(pcc_pdev);
617 }
618
619 return 0;
620 }
621
622 /*
623 * Make PCC init postcore so that users of this mailbox
624 * such as the ACPI Processor driver have it available
625 * at their init.
626 */
627 postcore_initcall(pcc_init);