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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2014 Linaro Ltd.
4 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
5 *
6 * PCC (Platform Communication Channel) is defined in the ACPI 5.0+
7 * specification. It is a mailbox like mechanism to allow clients
8 * such as CPPC (Collaborative Processor Performance Control), RAS
9 * (Reliability, Availability and Serviceability) and MPST (Memory
10 * Node Power State Table) to talk to the platform (e.g. BMC) through
11 * shared memory regions as defined in the PCC table entries. The PCC
12 * specification supports a Doorbell mechanism for the PCC clients
13 * to notify the platform about new data. This Doorbell information
14 * is also specified in each PCC table entry.
15 *
16 * Typical high level flow of operation is:
17 *
18 * PCC Reads:
19 * * Client tries to acquire a channel lock.
20 * * After it is acquired it writes READ cmd in communication region cmd
21 * address.
22 * * Client issues mbox_send_message() which rings the PCC doorbell
23 * for its PCC channel.
24 * * If command completes, then client has control over channel and
25 * it can proceed with its reads.
26 * * Client releases lock.
27 *
28 * PCC Writes:
29 * * Client tries to acquire channel lock.
30 * * Client writes to its communication region after it acquires a
31 * channel lock.
32 * * Client writes WRITE cmd in communication region cmd address.
33 * * Client issues mbox_send_message() which rings the PCC doorbell
34 * for its PCC channel.
35 * * If command completes, then writes have succeded and it can release
36 * the channel lock.
37 *
38 * There is a Nominal latency defined for each channel which indicates
39 * how long to wait until a command completes. If command is not complete
40 * the client needs to retry or assume failure.
41 *
42 * For more details about PCC, please see the ACPI specification from
43 * http://www.uefi.org/ACPIv5.1 Section 14.
44 *
45 * This file implements PCC as a Mailbox controller and allows for PCC
46 * clients to be implemented as its Mailbox Client Channels.
47 */
48
49#include <linux/acpi.h>
50#include <linux/delay.h>
51#include <linux/io.h>
52#include <linux/init.h>
53#include <linux/interrupt.h>
54#include <linux/list.h>
55#include <linux/platform_device.h>
56#include <linux/mailbox_controller.h>
57#include <linux/mailbox_client.h>
58#include <linux/io-64-nonatomic-lo-hi.h>
59#include <acpi/pcc.h>
60
61#include "mailbox.h"
62
63#define MBOX_IRQ_NAME "pcc-mbox"
64
65static struct mbox_chan *pcc_mbox_channels;
66
67/* Array of cached virtual address for doorbell registers */
68static void __iomem **pcc_doorbell_vaddr;
69/* Array of cached virtual address for doorbell ack registers */
70static void __iomem **pcc_doorbell_ack_vaddr;
71/* Array of doorbell interrupts */
72static int *pcc_doorbell_irq;
73
74static struct mbox_controller pcc_mbox_ctrl = {};
75/**
76 * get_pcc_channel - Given a PCC subspace idx, get
77 * the respective mbox_channel.
78 * @id: PCC subspace index.
79 *
80 * Return: ERR_PTR(errno) if error, else pointer
81 * to mbox channel.
82 */
83static struct mbox_chan *get_pcc_channel(int id)
84{
85 if (id < 0 || id >= pcc_mbox_ctrl.num_chans)
86 return ERR_PTR(-ENOENT);
87
88 return &pcc_mbox_channels[id];
89}
90
91/*
92 * PCC can be used with perf critical drivers such as CPPC
93 * So it makes sense to locally cache the virtual address and
94 * use it to read/write to PCC registers such as doorbell register
95 *
96 * The below read_register and write_registers are used to read and
97 * write from perf critical registers such as PCC doorbell register
98 */
99static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
100{
101 int ret_val = 0;
102
103 switch (bit_width) {
104 case 8:
105 *val = readb(vaddr);
106 break;
107 case 16:
108 *val = readw(vaddr);
109 break;
110 case 32:
111 *val = readl(vaddr);
112 break;
113 case 64:
114 *val = readq(vaddr);
115 break;
116 default:
117 pr_debug("Error: Cannot read register of %u bit width",
118 bit_width);
119 ret_val = -EFAULT;
120 break;
121 }
122 return ret_val;
123}
124
125static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
126{
127 int ret_val = 0;
128
129 switch (bit_width) {
130 case 8:
131 writeb(val, vaddr);
132 break;
133 case 16:
134 writew(val, vaddr);
135 break;
136 case 32:
137 writel(val, vaddr);
138 break;
139 case 64:
140 writeq(val, vaddr);
141 break;
142 default:
143 pr_debug("Error: Cannot write register of %u bit width",
144 bit_width);
145 ret_val = -EFAULT;
146 break;
147 }
148 return ret_val;
149}
150
151/**
152 * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number
153 * @interrupt: GSI number.
154 * @flags: interrupt flags
155 *
156 * Returns: a valid linux IRQ number on success
157 * 0 or -EINVAL on failure
158 */
159static int pcc_map_interrupt(u32 interrupt, u32 flags)
160{
161 int trigger, polarity;
162
163 if (!interrupt)
164 return 0;
165
166 trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
167 : ACPI_LEVEL_SENSITIVE;
168
169 polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
170 : ACPI_ACTIVE_HIGH;
171
172 return acpi_register_gsi(NULL, interrupt, trigger, polarity);
173}
174
175/**
176 * pcc_mbox_irq - PCC mailbox interrupt handler
177 */
178static irqreturn_t pcc_mbox_irq(int irq, void *p)
179{
180 struct acpi_generic_address *doorbell_ack;
181 struct acpi_pcct_hw_reduced *pcct_ss;
182 struct mbox_chan *chan = p;
183 u64 doorbell_ack_preserve;
184 u64 doorbell_ack_write;
185 u64 doorbell_ack_val;
186 int ret;
187
188 pcct_ss = chan->con_priv;
189
190 mbox_chan_received_data(chan, NULL);
191
192 if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
193 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = chan->con_priv;
194 u32 id = chan - pcc_mbox_channels;
195
196 doorbell_ack = &pcct2_ss->platform_ack_register;
197 doorbell_ack_preserve = pcct2_ss->ack_preserve_mask;
198 doorbell_ack_write = pcct2_ss->ack_write_mask;
199
200 ret = read_register(pcc_doorbell_ack_vaddr[id],
201 &doorbell_ack_val,
202 doorbell_ack->bit_width);
203 if (ret)
204 return IRQ_NONE;
205
206 ret = write_register(pcc_doorbell_ack_vaddr[id],
207 (doorbell_ack_val & doorbell_ack_preserve)
208 | doorbell_ack_write,
209 doorbell_ack->bit_width);
210 if (ret)
211 return IRQ_NONE;
212 }
213
214 return IRQ_HANDLED;
215}
216
217/**
218 * pcc_mbox_request_channel - PCC clients call this function to
219 * request a pointer to their PCC subspace, from which they
220 * can get the details of communicating with the remote.
221 * @cl: Pointer to Mailbox client, so we know where to bind the
222 * Channel.
223 * @subspace_id: The PCC Subspace index as parsed in the PCC client
224 * ACPI package. This is used to lookup the array of PCC
225 * subspaces as parsed by the PCC Mailbox controller.
226 *
227 * Return: Pointer to the Mailbox Channel if successful or
228 * ERR_PTR.
229 */
230struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
231 int subspace_id)
232{
233 struct device *dev = pcc_mbox_ctrl.dev;
234 struct mbox_chan *chan;
235 unsigned long flags;
236
237 /*
238 * Each PCC Subspace is a Mailbox Channel.
239 * The PCC Clients get their PCC Subspace ID
240 * from their own tables and pass it here.
241 * This returns a pointer to the PCC subspace
242 * for the Client to operate on.
243 */
244 chan = get_pcc_channel(subspace_id);
245
246 if (IS_ERR(chan) || chan->cl) {
247 dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
248 return ERR_PTR(-EBUSY);
249 }
250
251 spin_lock_irqsave(&chan->lock, flags);
252 chan->msg_free = 0;
253 chan->msg_count = 0;
254 chan->active_req = NULL;
255 chan->cl = cl;
256 init_completion(&chan->tx_complete);
257
258 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
259 chan->txdone_method = TXDONE_BY_ACK;
260
261 spin_unlock_irqrestore(&chan->lock, flags);
262
263 if (pcc_doorbell_irq[subspace_id] > 0) {
264 int rc;
265
266 rc = devm_request_irq(dev, pcc_doorbell_irq[subspace_id],
267 pcc_mbox_irq, 0, MBOX_IRQ_NAME, chan);
268 if (unlikely(rc)) {
269 dev_err(dev, "failed to register PCC interrupt %d\n",
270 pcc_doorbell_irq[subspace_id]);
271 pcc_mbox_free_channel(chan);
272 chan = ERR_PTR(rc);
273 }
274 }
275
276 return chan;
277}
278EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
279
280/**
281 * pcc_mbox_free_channel - Clients call this to free their Channel.
282 *
283 * @chan: Pointer to the mailbox channel as returned by
284 * pcc_mbox_request_channel()
285 */
286void pcc_mbox_free_channel(struct mbox_chan *chan)
287{
288 u32 id = chan - pcc_mbox_channels;
289 unsigned long flags;
290
291 if (!chan || !chan->cl)
292 return;
293
294 if (id >= pcc_mbox_ctrl.num_chans) {
295 pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n");
296 return;
297 }
298
299 if (pcc_doorbell_irq[id] > 0)
300 devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan);
301
302 spin_lock_irqsave(&chan->lock, flags);
303 chan->cl = NULL;
304 chan->active_req = NULL;
305 if (chan->txdone_method == TXDONE_BY_ACK)
306 chan->txdone_method = TXDONE_BY_POLL;
307
308 spin_unlock_irqrestore(&chan->lock, flags);
309}
310EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
311
312/**
313 * pcc_send_data - Called from Mailbox Controller code. Used
314 * here only to ring the channel doorbell. The PCC client
315 * specific read/write is done in the client driver in
316 * order to maintain atomicity over PCC channel once
317 * OS has control over it. See above for flow of operations.
318 * @chan: Pointer to Mailbox channel over which to send data.
319 * @data: Client specific data written over channel. Used here
320 * only for debug after PCC transaction completes.
321 *
322 * Return: Err if something failed else 0 for success.
323 */
324static int pcc_send_data(struct mbox_chan *chan, void *data)
325{
326 struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
327 struct acpi_generic_address *doorbell;
328 u64 doorbell_preserve;
329 u64 doorbell_val;
330 u64 doorbell_write;
331 u32 id = chan - pcc_mbox_channels;
332 int ret = 0;
333
334 if (id >= pcc_mbox_ctrl.num_chans) {
335 pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
336 return -ENOENT;
337 }
338
339 doorbell = &pcct_ss->doorbell_register;
340 doorbell_preserve = pcct_ss->preserve_mask;
341 doorbell_write = pcct_ss->write_mask;
342
343 /* Sync notification from OS to Platform. */
344 if (pcc_doorbell_vaddr[id]) {
345 ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
346 doorbell->bit_width);
347 if (ret)
348 return ret;
349 ret = write_register(pcc_doorbell_vaddr[id],
350 (doorbell_val & doorbell_preserve) | doorbell_write,
351 doorbell->bit_width);
352 } else {
353 ret = acpi_read(&doorbell_val, doorbell);
354 if (ret)
355 return ret;
356 ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
357 doorbell);
358 }
359 return ret;
360}
361
362static const struct mbox_chan_ops pcc_chan_ops = {
363 .send_data = pcc_send_data,
364};
365
366/**
367 * parse_pcc_subspaces -- Count PCC subspaces defined
368 * @header: Pointer to the ACPI subtable header under the PCCT.
369 * @end: End of subtable entry.
370 *
371 * Return: If we find a PCC subspace entry of a valid type, return 0.
372 * Otherwise, return -EINVAL.
373 *
374 * This gets called for each entry in the PCC table.
375 */
376static int parse_pcc_subspace(union acpi_subtable_headers *header,
377 const unsigned long end)
378{
379 struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;
380
381 if (ss->header.type < ACPI_PCCT_TYPE_RESERVED)
382 return 0;
383
384 return -EINVAL;
385}
386
387/**
388 * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
389 * There should be one entry per PCC client.
390 * @id: PCC subspace index.
391 * @pcct_ss: Pointer to the ACPI subtable header under the PCCT.
392 *
393 * Return: 0 for Success, else errno.
394 *
395 * This gets called for each entry in the PCC table.
396 */
397static int pcc_parse_subspace_irq(int id,
398 struct acpi_pcct_hw_reduced *pcct_ss)
399{
400 pcc_doorbell_irq[id] = pcc_map_interrupt(pcct_ss->platform_interrupt,
401 (u32)pcct_ss->flags);
402 if (pcc_doorbell_irq[id] <= 0) {
403 pr_err("PCC GSI %d not registered\n",
404 pcct_ss->platform_interrupt);
405 return -EINVAL;
406 }
407
408 if (pcct_ss->header.type
409 == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
410 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
411
412 pcc_doorbell_ack_vaddr[id] = acpi_os_ioremap(
413 pcct2_ss->platform_ack_register.address,
414 pcct2_ss->platform_ack_register.bit_width / 8);
415 if (!pcc_doorbell_ack_vaddr[id]) {
416 pr_err("Failed to ioremap PCC ACK register\n");
417 return -ENOMEM;
418 }
419 }
420
421 return 0;
422}
423
424/**
425 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
426 *
427 * Return: 0 for Success, else errno.
428 */
429static int __init acpi_pcc_probe(void)
430{
431 struct acpi_table_header *pcct_tbl;
432 struct acpi_subtable_header *pcct_entry;
433 struct acpi_table_pcct *acpi_pcct_tbl;
434 struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
435 int count, i, rc;
436 acpi_status status = AE_OK;
437
438 /* Search for PCCT */
439 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
440
441 if (ACPI_FAILURE(status) || !pcct_tbl)
442 return -ENODEV;
443
444 /* Set up the subtable handlers */
445 for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
446 i < ACPI_PCCT_TYPE_RESERVED; i++) {
447 proc[i].id = i;
448 proc[i].count = 0;
449 proc[i].handler = parse_pcc_subspace;
450 }
451
452 count = acpi_table_parse_entries_array(ACPI_SIG_PCCT,
453 sizeof(struct acpi_table_pcct), proc,
454 ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES);
455 if (count <= 0 || count > MAX_PCC_SUBSPACES) {
456 if (count < 0)
457 pr_warn("Error parsing PCC subspaces from PCCT\n");
458 else
459 pr_warn("Invalid PCCT: %d PCC subspaces\n", count);
460
461 rc = -EINVAL;
462 goto err_put_pcct;
463 }
464
465 pcc_mbox_channels = kcalloc(count, sizeof(struct mbox_chan),
466 GFP_KERNEL);
467 if (!pcc_mbox_channels) {
468 pr_err("Could not allocate space for PCC mbox channels\n");
469 rc = -ENOMEM;
470 goto err_put_pcct;
471 }
472
473 pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
474 if (!pcc_doorbell_vaddr) {
475 rc = -ENOMEM;
476 goto err_free_mbox;
477 }
478
479 pcc_doorbell_ack_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
480 if (!pcc_doorbell_ack_vaddr) {
481 rc = -ENOMEM;
482 goto err_free_db_vaddr;
483 }
484
485 pcc_doorbell_irq = kcalloc(count, sizeof(int), GFP_KERNEL);
486 if (!pcc_doorbell_irq) {
487 rc = -ENOMEM;
488 goto err_free_db_ack_vaddr;
489 }
490
491 /* Point to the first PCC subspace entry */
492 pcct_entry = (struct acpi_subtable_header *) (
493 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
494
495 acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
496 if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
497 pcc_mbox_ctrl.txdone_irq = true;
498
499 for (i = 0; i < count; i++) {
500 struct acpi_generic_address *db_reg;
501 struct acpi_pcct_subspace *pcct_ss;
502 pcc_mbox_channels[i].con_priv = pcct_entry;
503
504 if (pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
505 pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
506 struct acpi_pcct_hw_reduced *pcct_hrss;
507
508 pcct_hrss = (struct acpi_pcct_hw_reduced *) pcct_entry;
509
510 if (pcc_mbox_ctrl.txdone_irq) {
511 rc = pcc_parse_subspace_irq(i, pcct_hrss);
512 if (rc < 0)
513 goto err;
514 }
515 }
516 pcct_ss = (struct acpi_pcct_subspace *) pcct_entry;
517
518 /* If doorbell is in system memory cache the virt address */
519 db_reg = &pcct_ss->doorbell_register;
520 if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
521 pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
522 db_reg->bit_width/8);
523 pcct_entry = (struct acpi_subtable_header *)
524 ((unsigned long) pcct_entry + pcct_entry->length);
525 }
526
527 pcc_mbox_ctrl.num_chans = count;
528
529 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
530
531 return 0;
532
533err:
534 kfree(pcc_doorbell_irq);
535err_free_db_ack_vaddr:
536 kfree(pcc_doorbell_ack_vaddr);
537err_free_db_vaddr:
538 kfree(pcc_doorbell_vaddr);
539err_free_mbox:
540 kfree(pcc_mbox_channels);
541err_put_pcct:
542 acpi_put_table(pcct_tbl);
543 return rc;
544}
545
546/**
547 * pcc_mbox_probe - Called when we find a match for the
548 * PCCT platform device. This is purely used to represent
549 * the PCCT as a virtual device for registering with the
550 * generic Mailbox framework.
551 *
552 * @pdev: Pointer to platform device returned when a match
553 * is found.
554 *
555 * Return: 0 for Success, else errno.
556 */
557static int pcc_mbox_probe(struct platform_device *pdev)
558{
559 int ret = 0;
560
561 pcc_mbox_ctrl.chans = pcc_mbox_channels;
562 pcc_mbox_ctrl.ops = &pcc_chan_ops;
563 pcc_mbox_ctrl.dev = &pdev->dev;
564
565 pr_info("Registering PCC driver as Mailbox controller\n");
566 ret = mbox_controller_register(&pcc_mbox_ctrl);
567
568 if (ret) {
569 pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
570 ret = -ENODEV;
571 }
572
573 return ret;
574}
575
576static struct platform_driver pcc_mbox_driver = {
577 .probe = pcc_mbox_probe,
578 .driver = {
579 .name = "PCCT",
580 .owner = THIS_MODULE,
581 },
582};
583
584static int __init pcc_init(void)
585{
586 int ret;
587 struct platform_device *pcc_pdev;
588
589 if (acpi_disabled)
590 return -ENODEV;
591
592 /* Check if PCC support is available. */
593 ret = acpi_pcc_probe();
594
595 if (ret) {
596 pr_debug("ACPI PCC probe failed.\n");
597 return -ENODEV;
598 }
599
600 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
601 pcc_mbox_probe, NULL, 0, NULL, 0);
602
603 if (IS_ERR(pcc_pdev)) {
604 pr_debug("Err creating PCC platform bundle\n");
605 return PTR_ERR(pcc_pdev);
606 }
607
608 return 0;
609}
610
611/*
612 * Make PCC init postcore so that users of this mailbox
613 * such as the ACPI Processor driver have it available
614 * at their init.
615 */
616postcore_initcall(pcc_init);
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
75static struct mbox_chan *pcc_mbox_channels;
76
77/* Array of cached virtual address for doorbell registers */
78static void __iomem **pcc_doorbell_vaddr;
79/* Array of cached virtual address for doorbell ack registers */
80static void __iomem **pcc_doorbell_ack_vaddr;
81/* Array of doorbell interrupts */
82static int *pcc_doorbell_irq;
83
84static 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 */
93static 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 */
109static 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
135static 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 */
169static 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 */
188static 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 */
240struct 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}
288EXPORT_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 */
296void 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}
320EXPORT_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 */
334static 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
372static 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 */
386static 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 */
416static 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 */
448static int __init acpi_pcc_probe(void)
449{
450 struct acpi_table_header *pcct_tbl;
451 struct acpi_subtable_header *pcct_entry;
452 struct acpi_table_pcct *acpi_pcct_tbl;
453 int count, i, rc;
454 int sum = 0;
455 acpi_status status = AE_OK;
456
457 /* Search for PCCT */
458 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
459
460 if (ACPI_FAILURE(status) || !pcct_tbl) {
461 pr_warn("PCCT header not found.\n");
462 return -ENODEV;
463 }
464
465 count = acpi_table_parse_entries(ACPI_SIG_PCCT,
466 sizeof(struct acpi_table_pcct),
467 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
468 parse_pcc_subspace, MAX_PCC_SUBSPACES);
469 sum += (count > 0) ? count : 0;
470
471 count = acpi_table_parse_entries(ACPI_SIG_PCCT,
472 sizeof(struct acpi_table_pcct),
473 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2,
474 parse_pcc_subspace, MAX_PCC_SUBSPACES);
475 sum += (count > 0) ? count : 0;
476
477 if (sum == 0 || sum >= MAX_PCC_SUBSPACES) {
478 pr_err("Error parsing PCC subspaces from PCCT\n");
479 return -EINVAL;
480 }
481
482 pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
483 sum, GFP_KERNEL);
484 if (!pcc_mbox_channels) {
485 pr_err("Could not allocate space for PCC mbox channels\n");
486 return -ENOMEM;
487 }
488
489 pcc_doorbell_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
490 if (!pcc_doorbell_vaddr) {
491 rc = -ENOMEM;
492 goto err_free_mbox;
493 }
494
495 pcc_doorbell_ack_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
496 if (!pcc_doorbell_ack_vaddr) {
497 rc = -ENOMEM;
498 goto err_free_db_vaddr;
499 }
500
501 pcc_doorbell_irq = kcalloc(sum, sizeof(int), GFP_KERNEL);
502 if (!pcc_doorbell_irq) {
503 rc = -ENOMEM;
504 goto err_free_db_ack_vaddr;
505 }
506
507 /* Point to the first PCC subspace entry */
508 pcct_entry = (struct acpi_subtable_header *) (
509 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
510
511 acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
512 if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
513 pcc_mbox_ctrl.txdone_irq = true;
514
515 for (i = 0; i < sum; i++) {
516 struct acpi_generic_address *db_reg;
517 struct acpi_pcct_hw_reduced *pcct_ss;
518 pcc_mbox_channels[i].con_priv = pcct_entry;
519
520 pcct_ss = (struct acpi_pcct_hw_reduced *) pcct_entry;
521
522 if (pcc_mbox_ctrl.txdone_irq) {
523 rc = pcc_parse_subspace_irq(i, pcct_ss);
524 if (rc < 0)
525 goto err;
526 }
527
528 /* If doorbell is in system memory cache the virt address */
529 db_reg = &pcct_ss->doorbell_register;
530 if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
531 pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
532 db_reg->bit_width/8);
533 pcct_entry = (struct acpi_subtable_header *)
534 ((unsigned long) pcct_entry + pcct_entry->length);
535 }
536
537 pcc_mbox_ctrl.num_chans = sum;
538
539 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
540
541 return 0;
542
543err:
544 kfree(pcc_doorbell_irq);
545err_free_db_ack_vaddr:
546 kfree(pcc_doorbell_ack_vaddr);
547err_free_db_vaddr:
548 kfree(pcc_doorbell_vaddr);
549err_free_mbox:
550 kfree(pcc_mbox_channels);
551 return rc;
552}
553
554/**
555 * pcc_mbox_probe - Called when we find a match for the
556 * PCCT platform device. This is purely used to represent
557 * the PCCT as a virtual device for registering with the
558 * generic Mailbox framework.
559 *
560 * @pdev: Pointer to platform device returned when a match
561 * is found.
562 *
563 * Return: 0 for Success, else errno.
564 */
565static int pcc_mbox_probe(struct platform_device *pdev)
566{
567 int ret = 0;
568
569 pcc_mbox_ctrl.chans = pcc_mbox_channels;
570 pcc_mbox_ctrl.ops = &pcc_chan_ops;
571 pcc_mbox_ctrl.dev = &pdev->dev;
572
573 pr_info("Registering PCC driver as Mailbox controller\n");
574 ret = mbox_controller_register(&pcc_mbox_ctrl);
575
576 if (ret) {
577 pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
578 ret = -ENODEV;
579 }
580
581 return ret;
582}
583
584struct platform_driver pcc_mbox_driver = {
585 .probe = pcc_mbox_probe,
586 .driver = {
587 .name = "PCCT",
588 .owner = THIS_MODULE,
589 },
590};
591
592static int __init pcc_init(void)
593{
594 int ret;
595 struct platform_device *pcc_pdev;
596
597 if (acpi_disabled)
598 return -ENODEV;
599
600 /* Check if PCC support is available. */
601 ret = acpi_pcc_probe();
602
603 if (ret) {
604 pr_debug("ACPI PCC probe failed.\n");
605 return -ENODEV;
606 }
607
608 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
609 pcc_mbox_probe, NULL, 0, NULL, 0);
610
611 if (IS_ERR(pcc_pdev)) {
612 pr_debug("Err creating PCC platform bundle\n");
613 return PTR_ERR(pcc_pdev);
614 }
615
616 return 0;
617}
618
619/*
620 * Make PCC init postcore so that users of this mailbox
621 * such as the ACPI Processor driver have it available
622 * at their init.
623 */
624postcore_initcall(pcc_init);