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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/list.h>
63#include <linux/platform_device.h>
64#include <linux/mailbox_controller.h>
65#include <linux/mailbox_client.h>
66#include <linux/io-64-nonatomic-lo-hi.h>
67
68#include "mailbox.h"
69
70#define MAX_PCC_SUBSPACES 256
71
72static struct mbox_chan *pcc_mbox_channels;
73
74/* Array of cached virtual address for doorbell registers */
75static void __iomem **pcc_doorbell_vaddr;
76
77static struct mbox_controller pcc_mbox_ctrl = {};
78/**
79 * get_pcc_channel - Given a PCC subspace idx, get
80 * the respective mbox_channel.
81 * @id: PCC subspace index.
82 *
83 * Return: ERR_PTR(errno) if error, else pointer
84 * to mbox channel.
85 */
86static struct mbox_chan *get_pcc_channel(int id)
87{
88 if (id < 0 || id > pcc_mbox_ctrl.num_chans)
89 return ERR_PTR(-ENOENT);
90
91 return &pcc_mbox_channels[id];
92}
93
94/**
95 * pcc_mbox_request_channel - PCC clients call this function to
96 * request a pointer to their PCC subspace, from which they
97 * can get the details of communicating with the remote.
98 * @cl: Pointer to Mailbox client, so we know where to bind the
99 * Channel.
100 * @subspace_id: The PCC Subspace index as parsed in the PCC client
101 * ACPI package. This is used to lookup the array of PCC
102 * subspaces as parsed by the PCC Mailbox controller.
103 *
104 * Return: Pointer to the Mailbox Channel if successful or
105 * ERR_PTR.
106 */
107struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
108 int subspace_id)
109{
110 struct device *dev = pcc_mbox_ctrl.dev;
111 struct mbox_chan *chan;
112 unsigned long flags;
113
114 /*
115 * Each PCC Subspace is a Mailbox Channel.
116 * The PCC Clients get their PCC Subspace ID
117 * from their own tables and pass it here.
118 * This returns a pointer to the PCC subspace
119 * for the Client to operate on.
120 */
121 chan = get_pcc_channel(subspace_id);
122
123 if (IS_ERR(chan) || chan->cl) {
124 dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
125 return ERR_PTR(-EBUSY);
126 }
127
128 spin_lock_irqsave(&chan->lock, flags);
129 chan->msg_free = 0;
130 chan->msg_count = 0;
131 chan->active_req = NULL;
132 chan->cl = cl;
133 init_completion(&chan->tx_complete);
134
135 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
136 chan->txdone_method |= TXDONE_BY_ACK;
137
138 spin_unlock_irqrestore(&chan->lock, flags);
139
140 return chan;
141}
142EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
143
144/**
145 * pcc_mbox_free_channel - Clients call this to free their Channel.
146 *
147 * @chan: Pointer to the mailbox channel as returned by
148 * pcc_mbox_request_channel()
149 */
150void pcc_mbox_free_channel(struct mbox_chan *chan)
151{
152 unsigned long flags;
153
154 if (!chan || !chan->cl)
155 return;
156
157 spin_lock_irqsave(&chan->lock, flags);
158 chan->cl = NULL;
159 chan->active_req = NULL;
160 if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
161 chan->txdone_method = TXDONE_BY_POLL;
162
163 spin_unlock_irqrestore(&chan->lock, flags);
164}
165EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
166
167/*
168 * PCC can be used with perf critical drivers such as CPPC
169 * So it makes sense to locally cache the virtual address and
170 * use it to read/write to PCC registers such as doorbell register
171 *
172 * The below read_register and write_registers are used to read and
173 * write from perf critical registers such as PCC doorbell register
174 */
175static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
176{
177 int ret_val = 0;
178
179 switch (bit_width) {
180 case 8:
181 *val = readb(vaddr);
182 break;
183 case 16:
184 *val = readw(vaddr);
185 break;
186 case 32:
187 *val = readl(vaddr);
188 break;
189 case 64:
190 *val = readq(vaddr);
191 break;
192 default:
193 pr_debug("Error: Cannot read register of %u bit width",
194 bit_width);
195 ret_val = -EFAULT;
196 break;
197 }
198 return ret_val;
199}
200
201static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
202{
203 int ret_val = 0;
204
205 switch (bit_width) {
206 case 8:
207 writeb(val, vaddr);
208 break;
209 case 16:
210 writew(val, vaddr);
211 break;
212 case 32:
213 writel(val, vaddr);
214 break;
215 case 64:
216 writeq(val, vaddr);
217 break;
218 default:
219 pr_debug("Error: Cannot write register of %u bit width",
220 bit_width);
221 ret_val = -EFAULT;
222 break;
223 }
224 return ret_val;
225}
226
227/**
228 * pcc_send_data - Called from Mailbox Controller code. Used
229 * here only to ring the channel doorbell. The PCC client
230 * specific read/write is done in the client driver in
231 * order to maintain atomicity over PCC channel once
232 * OS has control over it. See above for flow of operations.
233 * @chan: Pointer to Mailbox channel over which to send data.
234 * @data: Client specific data written over channel. Used here
235 * only for debug after PCC transaction completes.
236 *
237 * Return: Err if something failed else 0 for success.
238 */
239static int pcc_send_data(struct mbox_chan *chan, void *data)
240{
241 struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
242 struct acpi_generic_address *doorbell;
243 u64 doorbell_preserve;
244 u64 doorbell_val;
245 u64 doorbell_write;
246 u32 id = chan - pcc_mbox_channels;
247 int ret = 0;
248
249 if (id >= pcc_mbox_ctrl.num_chans) {
250 pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
251 return -ENOENT;
252 }
253
254 doorbell = &pcct_ss->doorbell_register;
255 doorbell_preserve = pcct_ss->preserve_mask;
256 doorbell_write = pcct_ss->write_mask;
257
258 /* Sync notification from OS to Platform. */
259 if (pcc_doorbell_vaddr[id]) {
260 ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
261 doorbell->bit_width);
262 if (ret)
263 return ret;
264 ret = write_register(pcc_doorbell_vaddr[id],
265 (doorbell_val & doorbell_preserve) | doorbell_write,
266 doorbell->bit_width);
267 } else {
268 ret = acpi_read(&doorbell_val, doorbell);
269 if (ret)
270 return ret;
271 ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
272 doorbell);
273 }
274 return ret;
275}
276
277static const struct mbox_chan_ops pcc_chan_ops = {
278 .send_data = pcc_send_data,
279};
280
281/**
282 * parse_pcc_subspace - Parse the PCC table and verify PCC subspace
283 * entries. There should be one entry per PCC client.
284 * @header: Pointer to the ACPI subtable header under the PCCT.
285 * @end: End of subtable entry.
286 *
287 * Return: 0 for Success, else errno.
288 *
289 * This gets called for each entry in the PCC table.
290 */
291static int parse_pcc_subspace(struct acpi_subtable_header *header,
292 const unsigned long end)
293{
294 struct acpi_pcct_hw_reduced *pcct_ss;
295
296 if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
297 pcct_ss = (struct acpi_pcct_hw_reduced *) header;
298
299 if (pcct_ss->header.type !=
300 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) {
301 pr_err("Incorrect PCC Subspace type detected\n");
302 return -EINVAL;
303 }
304 }
305
306 return 0;
307}
308
309/**
310 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
311 *
312 * Return: 0 for Success, else errno.
313 */
314static int __init acpi_pcc_probe(void)
315{
316 acpi_size pcct_tbl_header_size;
317 struct acpi_table_header *pcct_tbl;
318 struct acpi_subtable_header *pcct_entry;
319 int count, i;
320 acpi_status status = AE_OK;
321
322 /* Search for PCCT */
323 status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,
324 &pcct_tbl,
325 &pcct_tbl_header_size);
326
327 if (ACPI_FAILURE(status) || !pcct_tbl) {
328 pr_warn("PCCT header not found.\n");
329 return -ENODEV;
330 }
331
332 count = acpi_table_parse_entries(ACPI_SIG_PCCT,
333 sizeof(struct acpi_table_pcct),
334 ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
335 parse_pcc_subspace, MAX_PCC_SUBSPACES);
336
337 if (count <= 0) {
338 pr_err("Error parsing PCC subspaces from PCCT\n");
339 return -EINVAL;
340 }
341
342 pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
343 count, GFP_KERNEL);
344
345 if (!pcc_mbox_channels) {
346 pr_err("Could not allocate space for PCC mbox channels\n");
347 return -ENOMEM;
348 }
349
350 pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
351 if (!pcc_doorbell_vaddr) {
352 kfree(pcc_mbox_channels);
353 return -ENOMEM;
354 }
355
356 /* Point to the first PCC subspace entry */
357 pcct_entry = (struct acpi_subtable_header *) (
358 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
359
360 for (i = 0; i < count; i++) {
361 struct acpi_generic_address *db_reg;
362 struct acpi_pcct_hw_reduced *pcct_ss;
363 pcc_mbox_channels[i].con_priv = pcct_entry;
364
365 /* If doorbell is in system memory cache the virt address */
366 pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
367 db_reg = &pcct_ss->doorbell_register;
368 if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
369 pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
370 db_reg->bit_width/8);
371 pcct_entry = (struct acpi_subtable_header *)
372 ((unsigned long) pcct_entry + pcct_entry->length);
373 }
374
375 pcc_mbox_ctrl.num_chans = count;
376
377 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
378
379 return 0;
380}
381
382/**
383 * pcc_mbox_probe - Called when we find a match for the
384 * PCCT platform device. This is purely used to represent
385 * the PCCT as a virtual device for registering with the
386 * generic Mailbox framework.
387 *
388 * @pdev: Pointer to platform device returned when a match
389 * is found.
390 *
391 * Return: 0 for Success, else errno.
392 */
393static int pcc_mbox_probe(struct platform_device *pdev)
394{
395 int ret = 0;
396
397 pcc_mbox_ctrl.chans = pcc_mbox_channels;
398 pcc_mbox_ctrl.ops = &pcc_chan_ops;
399 pcc_mbox_ctrl.dev = &pdev->dev;
400
401 pr_info("Registering PCC driver as Mailbox controller\n");
402 ret = mbox_controller_register(&pcc_mbox_ctrl);
403
404 if (ret) {
405 pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
406 ret = -ENODEV;
407 }
408
409 return ret;
410}
411
412struct platform_driver pcc_mbox_driver = {
413 .probe = pcc_mbox_probe,
414 .driver = {
415 .name = "PCCT",
416 .owner = THIS_MODULE,
417 },
418};
419
420static int __init pcc_init(void)
421{
422 int ret;
423 struct platform_device *pcc_pdev;
424
425 if (acpi_disabled)
426 return -ENODEV;
427
428 /* Check if PCC support is available. */
429 ret = acpi_pcc_probe();
430
431 if (ret) {
432 pr_debug("ACPI PCC probe failed.\n");
433 return -ENODEV;
434 }
435
436 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
437 pcc_mbox_probe, NULL, 0, NULL, 0);
438
439 if (IS_ERR(pcc_pdev)) {
440 pr_debug("Err creating PCC platform bundle\n");
441 return PTR_ERR(pcc_pdev);
442 }
443
444 return 0;
445}
446
447/*
448 * Make PCC init postcore so that users of this mailbox
449 * such as the ACPI Processor driver have it available
450 * at their init.
451 */
452postcore_initcall(pcc_init);