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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 succeeded 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/log2.h>
56#include <linux/platform_device.h>
57#include <linux/mailbox_controller.h>
58#include <linux/mailbox_client.h>
59#include <linux/io-64-nonatomic-lo-hi.h>
60#include <acpi/pcc.h>
61
62#include "mailbox.h"
63
64#define MBOX_IRQ_NAME "pcc-mbox"
65
66/**
67 * struct pcc_chan_reg - PCC register bundle
68 *
69 * @vaddr: cached virtual address for this register
70 * @gas: pointer to the generic address structure for this register
71 * @preserve_mask: bitmask to preserve when writing to this register
72 * @set_mask: bitmask to set when writing to this register
73 * @status_mask: bitmask to determine and/or update the status for this register
74 */
75struct pcc_chan_reg {
76 void __iomem *vaddr;
77 struct acpi_generic_address *gas;
78 u64 preserve_mask;
79 u64 set_mask;
80 u64 status_mask;
81};
82
83/**
84 * struct pcc_chan_info - PCC channel specific information
85 *
86 * @chan: PCC channel information with Shared Memory Region info
87 * @db: PCC register bundle for the doorbell register
88 * @plat_irq_ack: PCC register bundle for the platform interrupt acknowledge
89 * register
90 * @cmd_complete: PCC register bundle for the command complete check register
91 * @cmd_update: PCC register bundle for the command complete update register
92 * @error: PCC register bundle for the error status register
93 * @plat_irq: platform interrupt
94 */
95struct pcc_chan_info {
96 struct pcc_mbox_chan chan;
97 struct pcc_chan_reg db;
98 struct pcc_chan_reg plat_irq_ack;
99 struct pcc_chan_reg cmd_complete;
100 struct pcc_chan_reg cmd_update;
101 struct pcc_chan_reg error;
102 int plat_irq;
103};
104
105#define to_pcc_chan_info(c) container_of(c, struct pcc_chan_info, chan)
106static struct pcc_chan_info *chan_info;
107static int pcc_chan_count;
108
109/*
110 * PCC can be used with perf critical drivers such as CPPC
111 * So it makes sense to locally cache the virtual address and
112 * use it to read/write to PCC registers such as doorbell register
113 *
114 * The below read_register and write_registers are used to read and
115 * write from perf critical registers such as PCC doorbell register
116 */
117static void read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
118{
119 switch (bit_width) {
120 case 8:
121 *val = readb(vaddr);
122 break;
123 case 16:
124 *val = readw(vaddr);
125 break;
126 case 32:
127 *val = readl(vaddr);
128 break;
129 case 64:
130 *val = readq(vaddr);
131 break;
132 }
133}
134
135static void write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
136{
137 switch (bit_width) {
138 case 8:
139 writeb(val, vaddr);
140 break;
141 case 16:
142 writew(val, vaddr);
143 break;
144 case 32:
145 writel(val, vaddr);
146 break;
147 case 64:
148 writeq(val, vaddr);
149 break;
150 }
151}
152
153static int pcc_chan_reg_read(struct pcc_chan_reg *reg, u64 *val)
154{
155 int ret = 0;
156
157 if (!reg->gas) {
158 *val = 0;
159 return 0;
160 }
161
162 if (reg->vaddr)
163 read_register(reg->vaddr, val, reg->gas->bit_width);
164 else
165 ret = acpi_read(val, reg->gas);
166
167 return ret;
168}
169
170static int pcc_chan_reg_write(struct pcc_chan_reg *reg, u64 val)
171{
172 int ret = 0;
173
174 if (!reg->gas)
175 return 0;
176
177 if (reg->vaddr)
178 write_register(reg->vaddr, val, reg->gas->bit_width);
179 else
180 ret = acpi_write(val, reg->gas);
181
182 return ret;
183}
184
185static int pcc_chan_reg_read_modify_write(struct pcc_chan_reg *reg)
186{
187 int ret = 0;
188 u64 val;
189
190 ret = pcc_chan_reg_read(reg, &val);
191 if (ret)
192 return ret;
193
194 val &= reg->preserve_mask;
195 val |= reg->set_mask;
196
197 return pcc_chan_reg_write(reg, val);
198}
199
200/**
201 * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number
202 * @interrupt: GSI number.
203 * @flags: interrupt flags
204 *
205 * Returns: a valid linux IRQ number on success
206 * 0 or -EINVAL on failure
207 */
208static int pcc_map_interrupt(u32 interrupt, u32 flags)
209{
210 int trigger, polarity;
211
212 if (!interrupt)
213 return 0;
214
215 trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
216 : ACPI_LEVEL_SENSITIVE;
217
218 polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
219 : ACPI_ACTIVE_HIGH;
220
221 return acpi_register_gsi(NULL, interrupt, trigger, polarity);
222}
223
224/**
225 * pcc_mbox_irq - PCC mailbox interrupt handler
226 * @irq: interrupt number
227 * @p: data/cookie passed from the caller to identify the channel
228 *
229 * Returns: IRQ_HANDLED if interrupt is handled or IRQ_NONE if not
230 */
231static irqreturn_t pcc_mbox_irq(int irq, void *p)
232{
233 struct pcc_chan_info *pchan;
234 struct mbox_chan *chan = p;
235 u64 val;
236 int ret;
237
238 pchan = chan->con_priv;
239
240 ret = pcc_chan_reg_read(&pchan->cmd_complete, &val);
241 if (ret)
242 return IRQ_NONE;
243
244 if (val) { /* Ensure GAS exists and value is non-zero */
245 val &= pchan->cmd_complete.status_mask;
246 if (!val)
247 return IRQ_NONE;
248 }
249
250 ret = pcc_chan_reg_read(&pchan->error, &val);
251 if (ret)
252 return IRQ_NONE;
253 val &= pchan->error.status_mask;
254 if (val) {
255 val &= ~pchan->error.status_mask;
256 pcc_chan_reg_write(&pchan->error, val);
257 return IRQ_NONE;
258 }
259
260 if (pcc_chan_reg_read_modify_write(&pchan->plat_irq_ack))
261 return IRQ_NONE;
262
263 mbox_chan_received_data(chan, NULL);
264
265 return IRQ_HANDLED;
266}
267
268/**
269 * pcc_mbox_request_channel - PCC clients call this function to
270 * request a pointer to their PCC subspace, from which they
271 * can get the details of communicating with the remote.
272 * @cl: Pointer to Mailbox client, so we know where to bind the
273 * Channel.
274 * @subspace_id: The PCC Subspace index as parsed in the PCC client
275 * ACPI package. This is used to lookup the array of PCC
276 * subspaces as parsed by the PCC Mailbox controller.
277 *
278 * Return: Pointer to the PCC Mailbox Channel if successful or ERR_PTR.
279 */
280struct pcc_mbox_chan *
281pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
282{
283 struct pcc_chan_info *pchan;
284 struct mbox_chan *chan;
285 struct device *dev;
286 unsigned long flags;
287
288 if (subspace_id < 0 || subspace_id >= pcc_chan_count)
289 return ERR_PTR(-ENOENT);
290
291 pchan = chan_info + subspace_id;
292 chan = pchan->chan.mchan;
293 if (IS_ERR(chan) || chan->cl) {
294 pr_err("Channel not found for idx: %d\n", subspace_id);
295 return ERR_PTR(-EBUSY);
296 }
297 dev = chan->mbox->dev;
298
299 spin_lock_irqsave(&chan->lock, flags);
300 chan->msg_free = 0;
301 chan->msg_count = 0;
302 chan->active_req = NULL;
303 chan->cl = cl;
304 init_completion(&chan->tx_complete);
305
306 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
307 chan->txdone_method = TXDONE_BY_ACK;
308
309 spin_unlock_irqrestore(&chan->lock, flags);
310
311 if (pchan->plat_irq > 0) {
312 int rc;
313
314 rc = devm_request_irq(dev, pchan->plat_irq, pcc_mbox_irq, 0,
315 MBOX_IRQ_NAME, chan);
316 if (unlikely(rc)) {
317 dev_err(dev, "failed to register PCC interrupt %d\n",
318 pchan->plat_irq);
319 pcc_mbox_free_channel(&pchan->chan);
320 return ERR_PTR(rc);
321 }
322 }
323
324 return &pchan->chan;
325}
326EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
327
328/**
329 * pcc_mbox_free_channel - Clients call this to free their Channel.
330 *
331 * @pchan: Pointer to the PCC mailbox channel as returned by
332 * pcc_mbox_request_channel()
333 */
334void pcc_mbox_free_channel(struct pcc_mbox_chan *pchan)
335{
336 struct pcc_chan_info *pchan_info = to_pcc_chan_info(pchan);
337 struct mbox_chan *chan = pchan->mchan;
338 unsigned long flags;
339
340 if (!chan || !chan->cl)
341 return;
342
343 if (pchan_info->plat_irq > 0)
344 devm_free_irq(chan->mbox->dev, pchan_info->plat_irq, chan);
345
346 spin_lock_irqsave(&chan->lock, flags);
347 chan->cl = NULL;
348 chan->active_req = NULL;
349 if (chan->txdone_method == TXDONE_BY_ACK)
350 chan->txdone_method = TXDONE_BY_POLL;
351
352 spin_unlock_irqrestore(&chan->lock, flags);
353}
354EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
355
356/**
357 * pcc_send_data - Called from Mailbox Controller code. Used
358 * here only to ring the channel doorbell. The PCC client
359 * specific read/write is done in the client driver in
360 * order to maintain atomicity over PCC channel once
361 * OS has control over it. See above for flow of operations.
362 * @chan: Pointer to Mailbox channel over which to send data.
363 * @data: Client specific data written over channel. Used here
364 * only for debug after PCC transaction completes.
365 *
366 * Return: Err if something failed else 0 for success.
367 */
368static int pcc_send_data(struct mbox_chan *chan, void *data)
369{
370 int ret;
371 struct pcc_chan_info *pchan = chan->con_priv;
372
373 ret = pcc_chan_reg_read_modify_write(&pchan->cmd_update);
374 if (ret)
375 return ret;
376
377 return pcc_chan_reg_read_modify_write(&pchan->db);
378}
379
380static const struct mbox_chan_ops pcc_chan_ops = {
381 .send_data = pcc_send_data,
382};
383
384/**
385 * parse_pcc_subspace - Count PCC subspaces defined
386 * @header: Pointer to the ACPI subtable header under the PCCT.
387 * @end: End of subtable entry.
388 *
389 * Return: If we find a PCC subspace entry of a valid type, return 0.
390 * Otherwise, return -EINVAL.
391 *
392 * This gets called for each entry in the PCC table.
393 */
394static int parse_pcc_subspace(union acpi_subtable_headers *header,
395 const unsigned long end)
396{
397 struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;
398
399 if (ss->header.type < ACPI_PCCT_TYPE_RESERVED)
400 return 0;
401
402 return -EINVAL;
403}
404
405static int
406pcc_chan_reg_init(struct pcc_chan_reg *reg, struct acpi_generic_address *gas,
407 u64 preserve_mask, u64 set_mask, u64 status_mask, char *name)
408{
409 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
410 if (!(gas->bit_width >= 8 && gas->bit_width <= 64 &&
411 is_power_of_2(gas->bit_width))) {
412 pr_err("Error: Cannot access register of %u bit width",
413 gas->bit_width);
414 return -EFAULT;
415 }
416
417 reg->vaddr = acpi_os_ioremap(gas->address, gas->bit_width / 8);
418 if (!reg->vaddr) {
419 pr_err("Failed to ioremap PCC %s register\n", name);
420 return -ENOMEM;
421 }
422 }
423 reg->gas = gas;
424 reg->preserve_mask = preserve_mask;
425 reg->set_mask = set_mask;
426 reg->status_mask = status_mask;
427 return 0;
428}
429
430/**
431 * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
432 *
433 * @pchan: Pointer to the PCC channel info structure.
434 * @pcct_entry: Pointer to the ACPI subtable header.
435 *
436 * Return: 0 for Success, else errno.
437 *
438 * There should be one entry per PCC channel. This gets called for each
439 * entry in the PCC table. This uses PCCY Type1 structure for all applicable
440 * types(Type 1-4) to fetch irq
441 */
442static int pcc_parse_subspace_irq(struct pcc_chan_info *pchan,
443 struct acpi_subtable_header *pcct_entry)
444{
445 int ret = 0;
446 struct acpi_pcct_hw_reduced *pcct_ss;
447
448 if (pcct_entry->type < ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
449 pcct_entry->type > ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
450 return 0;
451
452 pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
453 pchan->plat_irq = pcc_map_interrupt(pcct_ss->platform_interrupt,
454 (u32)pcct_ss->flags);
455 if (pchan->plat_irq <= 0) {
456 pr_err("PCC GSI %d not registered\n",
457 pcct_ss->platform_interrupt);
458 return -EINVAL;
459 }
460
461 if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
462 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
463
464 ret = pcc_chan_reg_init(&pchan->plat_irq_ack,
465 &pcct2_ss->platform_ack_register,
466 pcct2_ss->ack_preserve_mask,
467 pcct2_ss->ack_write_mask, 0,
468 "PLAT IRQ ACK");
469
470 } else if (pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE ||
471 pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE) {
472 struct acpi_pcct_ext_pcc_master *pcct_ext = (void *)pcct_ss;
473
474 ret = pcc_chan_reg_init(&pchan->plat_irq_ack,
475 &pcct_ext->platform_ack_register,
476 pcct_ext->ack_preserve_mask,
477 pcct_ext->ack_set_mask, 0,
478 "PLAT IRQ ACK");
479 }
480
481 return ret;
482}
483
484/**
485 * pcc_parse_subspace_db_reg - Parse the PCC doorbell register
486 *
487 * @pchan: Pointer to the PCC channel info structure.
488 * @pcct_entry: Pointer to the ACPI subtable header.
489 *
490 * Return: 0 for Success, else errno.
491 */
492static int pcc_parse_subspace_db_reg(struct pcc_chan_info *pchan,
493 struct acpi_subtable_header *pcct_entry)
494{
495 int ret = 0;
496
497 if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
498 struct acpi_pcct_subspace *pcct_ss;
499
500 pcct_ss = (struct acpi_pcct_subspace *)pcct_entry;
501
502 ret = pcc_chan_reg_init(&pchan->db,
503 &pcct_ss->doorbell_register,
504 pcct_ss->preserve_mask,
505 pcct_ss->write_mask, 0, "Doorbell");
506
507 } else {
508 struct acpi_pcct_ext_pcc_master *pcct_ext;
509
510 pcct_ext = (struct acpi_pcct_ext_pcc_master *)pcct_entry;
511
512 ret = pcc_chan_reg_init(&pchan->db,
513 &pcct_ext->doorbell_register,
514 pcct_ext->preserve_mask,
515 pcct_ext->write_mask, 0, "Doorbell");
516 if (ret)
517 return ret;
518
519 ret = pcc_chan_reg_init(&pchan->cmd_complete,
520 &pcct_ext->cmd_complete_register,
521 0, 0, pcct_ext->cmd_complete_mask,
522 "Command Complete Check");
523 if (ret)
524 return ret;
525
526 ret = pcc_chan_reg_init(&pchan->cmd_update,
527 &pcct_ext->cmd_update_register,
528 pcct_ext->cmd_update_preserve_mask,
529 pcct_ext->cmd_update_set_mask, 0,
530 "Command Complete Update");
531 if (ret)
532 return ret;
533
534 ret = pcc_chan_reg_init(&pchan->error,
535 &pcct_ext->error_status_register,
536 0, 0, pcct_ext->error_status_mask,
537 "Error Status");
538 }
539 return ret;
540}
541
542/**
543 * pcc_parse_subspace_shmem - Parse the PCC Shared Memory Region information
544 *
545 * @pchan: Pointer to the PCC channel info structure.
546 * @pcct_entry: Pointer to the ACPI subtable header.
547 *
548 */
549static void pcc_parse_subspace_shmem(struct pcc_chan_info *pchan,
550 struct acpi_subtable_header *pcct_entry)
551{
552 if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
553 struct acpi_pcct_subspace *pcct_ss =
554 (struct acpi_pcct_subspace *)pcct_entry;
555
556 pchan->chan.shmem_base_addr = pcct_ss->base_address;
557 pchan->chan.shmem_size = pcct_ss->length;
558 pchan->chan.latency = pcct_ss->latency;
559 pchan->chan.max_access_rate = pcct_ss->max_access_rate;
560 pchan->chan.min_turnaround_time = pcct_ss->min_turnaround_time;
561 } else {
562 struct acpi_pcct_ext_pcc_master *pcct_ext =
563 (struct acpi_pcct_ext_pcc_master *)pcct_entry;
564
565 pchan->chan.shmem_base_addr = pcct_ext->base_address;
566 pchan->chan.shmem_size = pcct_ext->length;
567 pchan->chan.latency = pcct_ext->latency;
568 pchan->chan.max_access_rate = pcct_ext->max_access_rate;
569 pchan->chan.min_turnaround_time = pcct_ext->min_turnaround_time;
570 }
571}
572
573/**
574 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
575 *
576 * Return: 0 for Success, else errno.
577 */
578static int __init acpi_pcc_probe(void)
579{
580 int count, i, rc = 0;
581 acpi_status status;
582 struct acpi_table_header *pcct_tbl;
583 struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
584
585 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
586 if (ACPI_FAILURE(status) || !pcct_tbl)
587 return -ENODEV;
588
589 /* Set up the subtable handlers */
590 for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
591 i < ACPI_PCCT_TYPE_RESERVED; i++) {
592 proc[i].id = i;
593 proc[i].count = 0;
594 proc[i].handler = parse_pcc_subspace;
595 }
596
597 count = acpi_table_parse_entries_array(ACPI_SIG_PCCT,
598 sizeof(struct acpi_table_pcct), proc,
599 ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES);
600 if (count <= 0 || count > MAX_PCC_SUBSPACES) {
601 if (count < 0)
602 pr_warn("Error parsing PCC subspaces from PCCT\n");
603 else
604 pr_warn("Invalid PCCT: %d PCC subspaces\n", count);
605
606 rc = -EINVAL;
607 } else {
608 pcc_chan_count = count;
609 }
610
611 acpi_put_table(pcct_tbl);
612
613 return rc;
614}
615
616/**
617 * pcc_mbox_probe - Called when we find a match for the
618 * PCCT platform device. This is purely used to represent
619 * the PCCT as a virtual device for registering with the
620 * generic Mailbox framework.
621 *
622 * @pdev: Pointer to platform device returned when a match
623 * is found.
624 *
625 * Return: 0 for Success, else errno.
626 */
627static int pcc_mbox_probe(struct platform_device *pdev)
628{
629 struct device *dev = &pdev->dev;
630 struct mbox_controller *pcc_mbox_ctrl;
631 struct mbox_chan *pcc_mbox_channels;
632 struct acpi_table_header *pcct_tbl;
633 struct acpi_subtable_header *pcct_entry;
634 struct acpi_table_pcct *acpi_pcct_tbl;
635 acpi_status status = AE_OK;
636 int i, rc, count = pcc_chan_count;
637
638 /* Search for PCCT */
639 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
640
641 if (ACPI_FAILURE(status) || !pcct_tbl)
642 return -ENODEV;
643
644 pcc_mbox_channels = devm_kcalloc(dev, count, sizeof(*pcc_mbox_channels),
645 GFP_KERNEL);
646 if (!pcc_mbox_channels) {
647 rc = -ENOMEM;
648 goto err;
649 }
650
651 chan_info = devm_kcalloc(dev, count, sizeof(*chan_info), GFP_KERNEL);
652 if (!chan_info) {
653 rc = -ENOMEM;
654 goto err;
655 }
656
657 pcc_mbox_ctrl = devm_kzalloc(dev, sizeof(*pcc_mbox_ctrl), GFP_KERNEL);
658 if (!pcc_mbox_ctrl) {
659 rc = -ENOMEM;
660 goto err;
661 }
662
663 /* Point to the first PCC subspace entry */
664 pcct_entry = (struct acpi_subtable_header *) (
665 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
666
667 acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
668 if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
669 pcc_mbox_ctrl->txdone_irq = true;
670
671 for (i = 0; i < count; i++) {
672 struct pcc_chan_info *pchan = chan_info + i;
673
674 pcc_mbox_channels[i].con_priv = pchan;
675 pchan->chan.mchan = &pcc_mbox_channels[i];
676
677 if (pcct_entry->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE &&
678 !pcc_mbox_ctrl->txdone_irq) {
679 pr_err("Platform Interrupt flag must be set to 1");
680 rc = -EINVAL;
681 goto err;
682 }
683
684 if (pcc_mbox_ctrl->txdone_irq) {
685 rc = pcc_parse_subspace_irq(pchan, pcct_entry);
686 if (rc < 0)
687 goto err;
688 }
689 rc = pcc_parse_subspace_db_reg(pchan, pcct_entry);
690 if (rc < 0)
691 goto err;
692
693 pcc_parse_subspace_shmem(pchan, pcct_entry);
694
695 pcct_entry = (struct acpi_subtable_header *)
696 ((unsigned long) pcct_entry + pcct_entry->length);
697 }
698
699 pcc_mbox_ctrl->num_chans = count;
700
701 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl->num_chans);
702
703 pcc_mbox_ctrl->chans = pcc_mbox_channels;
704 pcc_mbox_ctrl->ops = &pcc_chan_ops;
705 pcc_mbox_ctrl->dev = dev;
706
707 pr_info("Registering PCC driver as Mailbox controller\n");
708 rc = mbox_controller_register(pcc_mbox_ctrl);
709 if (rc)
710 pr_err("Err registering PCC as Mailbox controller: %d\n", rc);
711 else
712 return 0;
713err:
714 acpi_put_table(pcct_tbl);
715 return rc;
716}
717
718static struct platform_driver pcc_mbox_driver = {
719 .probe = pcc_mbox_probe,
720 .driver = {
721 .name = "PCCT",
722 },
723};
724
725static int __init pcc_init(void)
726{
727 int ret;
728 struct platform_device *pcc_pdev;
729
730 if (acpi_disabled)
731 return -ENODEV;
732
733 /* Check if PCC support is available. */
734 ret = acpi_pcc_probe();
735
736 if (ret) {
737 pr_debug("ACPI PCC probe failed.\n");
738 return -ENODEV;
739 }
740
741 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
742 pcc_mbox_probe, NULL, 0, NULL, 0);
743
744 if (IS_ERR(pcc_pdev)) {
745 pr_debug("Err creating PCC platform bundle\n");
746 pcc_chan_count = 0;
747 return PTR_ERR(pcc_pdev);
748 }
749
750 return 0;
751}
752
753/*
754 * Make PCC init postcore so that users of this mailbox
755 * such as the ACPI Processor driver have it available
756 * at their init.
757 */
758postcore_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);