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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 * @type: PCC subspace type
95 * @plat_irq_flags: platform interrupt flags
96 * @chan_in_use: this flag is used just to check if the interrupt needs
97 * handling when it is shared. Since only one transfer can occur
98 * at a time and mailbox takes care of locking, this flag can be
99 * accessed without a lock. Note: the type only support the
100 * communication from OSPM to Platform, like type3, use it, and
101 * other types completely ignore it.
102 */
103struct pcc_chan_info {
104 struct pcc_mbox_chan chan;
105 struct pcc_chan_reg db;
106 struct pcc_chan_reg plat_irq_ack;
107 struct pcc_chan_reg cmd_complete;
108 struct pcc_chan_reg cmd_update;
109 struct pcc_chan_reg error;
110 int plat_irq;
111 u8 type;
112 unsigned int plat_irq_flags;
113 bool chan_in_use;
114};
115
116#define to_pcc_chan_info(c) container_of(c, struct pcc_chan_info, chan)
117static struct pcc_chan_info *chan_info;
118static int pcc_chan_count;
119
120static int pcc_send_data(struct mbox_chan *chan, void *data);
121
122/*
123 * PCC can be used with perf critical drivers such as CPPC
124 * So it makes sense to locally cache the virtual address and
125 * use it to read/write to PCC registers such as doorbell register
126 *
127 * The below read_register and write_registers are used to read and
128 * write from perf critical registers such as PCC doorbell register
129 */
130static void read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
131{
132 switch (bit_width) {
133 case 8:
134 *val = readb(vaddr);
135 break;
136 case 16:
137 *val = readw(vaddr);
138 break;
139 case 32:
140 *val = readl(vaddr);
141 break;
142 case 64:
143 *val = readq(vaddr);
144 break;
145 }
146}
147
148static void write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
149{
150 switch (bit_width) {
151 case 8:
152 writeb(val, vaddr);
153 break;
154 case 16:
155 writew(val, vaddr);
156 break;
157 case 32:
158 writel(val, vaddr);
159 break;
160 case 64:
161 writeq(val, vaddr);
162 break;
163 }
164}
165
166static int pcc_chan_reg_read(struct pcc_chan_reg *reg, u64 *val)
167{
168 int ret = 0;
169
170 if (!reg->gas) {
171 *val = 0;
172 return 0;
173 }
174
175 if (reg->vaddr)
176 read_register(reg->vaddr, val, reg->gas->bit_width);
177 else
178 ret = acpi_read(val, reg->gas);
179
180 return ret;
181}
182
183static int pcc_chan_reg_write(struct pcc_chan_reg *reg, u64 val)
184{
185 int ret = 0;
186
187 if (!reg->gas)
188 return 0;
189
190 if (reg->vaddr)
191 write_register(reg->vaddr, val, reg->gas->bit_width);
192 else
193 ret = acpi_write(val, reg->gas);
194
195 return ret;
196}
197
198static int pcc_chan_reg_read_modify_write(struct pcc_chan_reg *reg)
199{
200 int ret = 0;
201 u64 val;
202
203 ret = pcc_chan_reg_read(reg, &val);
204 if (ret)
205 return ret;
206
207 val &= reg->preserve_mask;
208 val |= reg->set_mask;
209
210 return pcc_chan_reg_write(reg, val);
211}
212
213/**
214 * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number
215 * @interrupt: GSI number.
216 * @flags: interrupt flags
217 *
218 * Returns: a valid linux IRQ number on success
219 * 0 or -EINVAL on failure
220 */
221static int pcc_map_interrupt(u32 interrupt, u32 flags)
222{
223 int trigger, polarity;
224
225 if (!interrupt)
226 return 0;
227
228 trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
229 : ACPI_LEVEL_SENSITIVE;
230
231 polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
232 : ACPI_ACTIVE_HIGH;
233
234 return acpi_register_gsi(NULL, interrupt, trigger, polarity);
235}
236
237static bool pcc_chan_plat_irq_can_be_shared(struct pcc_chan_info *pchan)
238{
239 return (pchan->plat_irq_flags & ACPI_PCCT_INTERRUPT_MODE) ==
240 ACPI_LEVEL_SENSITIVE;
241}
242
243static bool pcc_mbox_cmd_complete_check(struct pcc_chan_info *pchan)
244{
245 u64 val;
246 int ret;
247
248 ret = pcc_chan_reg_read(&pchan->cmd_complete, &val);
249 if (ret)
250 return false;
251
252 if (!pchan->cmd_complete.gas)
253 return true;
254
255 /*
256 * Judge if the channel respond the interrupt based on the value of
257 * command complete.
258 */
259 val &= pchan->cmd_complete.status_mask;
260
261 /*
262 * If this is PCC slave subspace channel, and the command complete
263 * bit 0 indicates that Platform is sending a notification and OSPM
264 * needs to respond this interrupt to process this command.
265 */
266 if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
267 return !val;
268
269 return !!val;
270}
271
272/**
273 * pcc_mbox_irq - PCC mailbox interrupt handler
274 * @irq: interrupt number
275 * @p: data/cookie passed from the caller to identify the channel
276 *
277 * Returns: IRQ_HANDLED if interrupt is handled or IRQ_NONE if not
278 */
279static irqreturn_t pcc_mbox_irq(int irq, void *p)
280{
281 struct pcc_chan_info *pchan;
282 struct mbox_chan *chan = p;
283 u64 val;
284 int ret;
285
286 pchan = chan->con_priv;
287 if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE &&
288 !pchan->chan_in_use)
289 return IRQ_NONE;
290
291 if (!pcc_mbox_cmd_complete_check(pchan))
292 return IRQ_NONE;
293
294 ret = pcc_chan_reg_read(&pchan->error, &val);
295 if (ret)
296 return IRQ_NONE;
297 val &= pchan->error.status_mask;
298 if (val) {
299 val &= ~pchan->error.status_mask;
300 pcc_chan_reg_write(&pchan->error, val);
301 return IRQ_NONE;
302 }
303
304 if (pcc_chan_reg_read_modify_write(&pchan->plat_irq_ack))
305 return IRQ_NONE;
306
307 mbox_chan_received_data(chan, NULL);
308
309 /*
310 * The PCC slave subspace channel needs to set the command complete bit
311 * and ring doorbell after processing message.
312 *
313 * The PCC master subspace channel clears chan_in_use to free channel.
314 */
315 if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
316 pcc_send_data(chan, NULL);
317 pchan->chan_in_use = false;
318
319 return IRQ_HANDLED;
320}
321
322/**
323 * pcc_mbox_request_channel - PCC clients call this function to
324 * request a pointer to their PCC subspace, from which they
325 * can get the details of communicating with the remote.
326 * @cl: Pointer to Mailbox client, so we know where to bind the
327 * Channel.
328 * @subspace_id: The PCC Subspace index as parsed in the PCC client
329 * ACPI package. This is used to lookup the array of PCC
330 * subspaces as parsed by the PCC Mailbox controller.
331 *
332 * Return: Pointer to the PCC Mailbox Channel if successful or ERR_PTR.
333 */
334struct pcc_mbox_chan *
335pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
336{
337 struct pcc_chan_info *pchan;
338 struct mbox_chan *chan;
339 int rc;
340
341 if (subspace_id < 0 || subspace_id >= pcc_chan_count)
342 return ERR_PTR(-ENOENT);
343
344 pchan = chan_info + subspace_id;
345 chan = pchan->chan.mchan;
346 if (IS_ERR(chan) || chan->cl) {
347 pr_err("Channel not found for idx: %d\n", subspace_id);
348 return ERR_PTR(-EBUSY);
349 }
350
351 rc = mbox_bind_client(chan, cl);
352 if (rc)
353 return ERR_PTR(rc);
354
355 return &pchan->chan;
356}
357EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
358
359/**
360 * pcc_mbox_free_channel - Clients call this to free their Channel.
361 *
362 * @pchan: Pointer to the PCC mailbox channel as returned by
363 * pcc_mbox_request_channel()
364 */
365void pcc_mbox_free_channel(struct pcc_mbox_chan *pchan)
366{
367 struct mbox_chan *chan = pchan->mchan;
368
369 if (!chan || !chan->cl)
370 return;
371
372 mbox_free_channel(chan);
373}
374EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
375
376/**
377 * pcc_send_data - Called from Mailbox Controller code. Used
378 * here only to ring the channel doorbell. The PCC client
379 * specific read/write is done in the client driver in
380 * order to maintain atomicity over PCC channel once
381 * OS has control over it. See above for flow of operations.
382 * @chan: Pointer to Mailbox channel over which to send data.
383 * @data: Client specific data written over channel. Used here
384 * only for debug after PCC transaction completes.
385 *
386 * Return: Err if something failed else 0 for success.
387 */
388static int pcc_send_data(struct mbox_chan *chan, void *data)
389{
390 int ret;
391 struct pcc_chan_info *pchan = chan->con_priv;
392
393 ret = pcc_chan_reg_read_modify_write(&pchan->cmd_update);
394 if (ret)
395 return ret;
396
397 ret = pcc_chan_reg_read_modify_write(&pchan->db);
398 if (!ret && pchan->plat_irq > 0)
399 pchan->chan_in_use = true;
400
401 return ret;
402}
403
404/**
405 * pcc_startup - Called from Mailbox Controller code. Used here
406 * to request the interrupt.
407 * @chan: Pointer to Mailbox channel to startup.
408 *
409 * Return: Err if something failed else 0 for success.
410 */
411static int pcc_startup(struct mbox_chan *chan)
412{
413 struct pcc_chan_info *pchan = chan->con_priv;
414 unsigned long irqflags;
415 int rc;
416
417 if (pchan->plat_irq > 0) {
418 irqflags = pcc_chan_plat_irq_can_be_shared(pchan) ?
419 IRQF_SHARED | IRQF_ONESHOT : 0;
420 rc = devm_request_irq(chan->mbox->dev, pchan->plat_irq, pcc_mbox_irq,
421 irqflags, MBOX_IRQ_NAME, chan);
422 if (unlikely(rc)) {
423 dev_err(chan->mbox->dev, "failed to register PCC interrupt %d\n",
424 pchan->plat_irq);
425 return rc;
426 }
427 }
428
429 return 0;
430}
431
432/**
433 * pcc_shutdown - Called from Mailbox Controller code. Used here
434 * to free the interrupt.
435 * @chan: Pointer to Mailbox channel to shutdown.
436 */
437static void pcc_shutdown(struct mbox_chan *chan)
438{
439 struct pcc_chan_info *pchan = chan->con_priv;
440
441 if (pchan->plat_irq > 0)
442 devm_free_irq(chan->mbox->dev, pchan->plat_irq, chan);
443}
444
445static const struct mbox_chan_ops pcc_chan_ops = {
446 .send_data = pcc_send_data,
447 .startup = pcc_startup,
448 .shutdown = pcc_shutdown,
449};
450
451/**
452 * parse_pcc_subspace - Count PCC subspaces defined
453 * @header: Pointer to the ACPI subtable header under the PCCT.
454 * @end: End of subtable entry.
455 *
456 * Return: If we find a PCC subspace entry of a valid type, return 0.
457 * Otherwise, return -EINVAL.
458 *
459 * This gets called for each entry in the PCC table.
460 */
461static int parse_pcc_subspace(union acpi_subtable_headers *header,
462 const unsigned long end)
463{
464 struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;
465
466 if (ss->header.type < ACPI_PCCT_TYPE_RESERVED)
467 return 0;
468
469 return -EINVAL;
470}
471
472static int
473pcc_chan_reg_init(struct pcc_chan_reg *reg, struct acpi_generic_address *gas,
474 u64 preserve_mask, u64 set_mask, u64 status_mask, char *name)
475{
476 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
477 if (!(gas->bit_width >= 8 && gas->bit_width <= 64 &&
478 is_power_of_2(gas->bit_width))) {
479 pr_err("Error: Cannot access register of %u bit width",
480 gas->bit_width);
481 return -EFAULT;
482 }
483
484 reg->vaddr = acpi_os_ioremap(gas->address, gas->bit_width / 8);
485 if (!reg->vaddr) {
486 pr_err("Failed to ioremap PCC %s register\n", name);
487 return -ENOMEM;
488 }
489 }
490 reg->gas = gas;
491 reg->preserve_mask = preserve_mask;
492 reg->set_mask = set_mask;
493 reg->status_mask = status_mask;
494 return 0;
495}
496
497/**
498 * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
499 *
500 * @pchan: Pointer to the PCC channel info structure.
501 * @pcct_entry: Pointer to the ACPI subtable header.
502 *
503 * Return: 0 for Success, else errno.
504 *
505 * There should be one entry per PCC channel. This gets called for each
506 * entry in the PCC table. This uses PCCY Type1 structure for all applicable
507 * types(Type 1-4) to fetch irq
508 */
509static int pcc_parse_subspace_irq(struct pcc_chan_info *pchan,
510 struct acpi_subtable_header *pcct_entry)
511{
512 int ret = 0;
513 struct acpi_pcct_hw_reduced *pcct_ss;
514
515 if (pcct_entry->type < ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
516 pcct_entry->type > ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
517 return 0;
518
519 pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
520 pchan->plat_irq = pcc_map_interrupt(pcct_ss->platform_interrupt,
521 (u32)pcct_ss->flags);
522 if (pchan->plat_irq <= 0) {
523 pr_err("PCC GSI %d not registered\n",
524 pcct_ss->platform_interrupt);
525 return -EINVAL;
526 }
527 pchan->plat_irq_flags = pcct_ss->flags;
528
529 if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
530 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
531
532 ret = pcc_chan_reg_init(&pchan->plat_irq_ack,
533 &pcct2_ss->platform_ack_register,
534 pcct2_ss->ack_preserve_mask,
535 pcct2_ss->ack_write_mask, 0,
536 "PLAT IRQ ACK");
537
538 } else if (pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE ||
539 pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE) {
540 struct acpi_pcct_ext_pcc_master *pcct_ext = (void *)pcct_ss;
541
542 ret = pcc_chan_reg_init(&pchan->plat_irq_ack,
543 &pcct_ext->platform_ack_register,
544 pcct_ext->ack_preserve_mask,
545 pcct_ext->ack_set_mask, 0,
546 "PLAT IRQ ACK");
547 }
548
549 if (pcc_chan_plat_irq_can_be_shared(pchan) &&
550 !pchan->plat_irq_ack.gas) {
551 pr_err("PCC subspace has level IRQ with no ACK register\n");
552 return -EINVAL;
553 }
554
555 return ret;
556}
557
558/**
559 * pcc_parse_subspace_db_reg - Parse the PCC doorbell register
560 *
561 * @pchan: Pointer to the PCC channel info structure.
562 * @pcct_entry: Pointer to the ACPI subtable header.
563 *
564 * Return: 0 for Success, else errno.
565 */
566static int pcc_parse_subspace_db_reg(struct pcc_chan_info *pchan,
567 struct acpi_subtable_header *pcct_entry)
568{
569 int ret = 0;
570
571 if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
572 struct acpi_pcct_subspace *pcct_ss;
573
574 pcct_ss = (struct acpi_pcct_subspace *)pcct_entry;
575
576 ret = pcc_chan_reg_init(&pchan->db,
577 &pcct_ss->doorbell_register,
578 pcct_ss->preserve_mask,
579 pcct_ss->write_mask, 0, "Doorbell");
580
581 } else {
582 struct acpi_pcct_ext_pcc_master *pcct_ext;
583
584 pcct_ext = (struct acpi_pcct_ext_pcc_master *)pcct_entry;
585
586 ret = pcc_chan_reg_init(&pchan->db,
587 &pcct_ext->doorbell_register,
588 pcct_ext->preserve_mask,
589 pcct_ext->write_mask, 0, "Doorbell");
590 if (ret)
591 return ret;
592
593 ret = pcc_chan_reg_init(&pchan->cmd_complete,
594 &pcct_ext->cmd_complete_register,
595 0, 0, pcct_ext->cmd_complete_mask,
596 "Command Complete Check");
597 if (ret)
598 return ret;
599
600 ret = pcc_chan_reg_init(&pchan->cmd_update,
601 &pcct_ext->cmd_update_register,
602 pcct_ext->cmd_update_preserve_mask,
603 pcct_ext->cmd_update_set_mask, 0,
604 "Command Complete Update");
605 if (ret)
606 return ret;
607
608 ret = pcc_chan_reg_init(&pchan->error,
609 &pcct_ext->error_status_register,
610 0, 0, pcct_ext->error_status_mask,
611 "Error Status");
612 }
613 return ret;
614}
615
616/**
617 * pcc_parse_subspace_shmem - Parse the PCC Shared Memory Region information
618 *
619 * @pchan: Pointer to the PCC channel info structure.
620 * @pcct_entry: Pointer to the ACPI subtable header.
621 *
622 */
623static void pcc_parse_subspace_shmem(struct pcc_chan_info *pchan,
624 struct acpi_subtable_header *pcct_entry)
625{
626 if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
627 struct acpi_pcct_subspace *pcct_ss =
628 (struct acpi_pcct_subspace *)pcct_entry;
629
630 pchan->chan.shmem_base_addr = pcct_ss->base_address;
631 pchan->chan.shmem_size = pcct_ss->length;
632 pchan->chan.latency = pcct_ss->latency;
633 pchan->chan.max_access_rate = pcct_ss->max_access_rate;
634 pchan->chan.min_turnaround_time = pcct_ss->min_turnaround_time;
635 } else {
636 struct acpi_pcct_ext_pcc_master *pcct_ext =
637 (struct acpi_pcct_ext_pcc_master *)pcct_entry;
638
639 pchan->chan.shmem_base_addr = pcct_ext->base_address;
640 pchan->chan.shmem_size = pcct_ext->length;
641 pchan->chan.latency = pcct_ext->latency;
642 pchan->chan.max_access_rate = pcct_ext->max_access_rate;
643 pchan->chan.min_turnaround_time = pcct_ext->min_turnaround_time;
644 }
645}
646
647/**
648 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
649 *
650 * Return: 0 for Success, else errno.
651 */
652static int __init acpi_pcc_probe(void)
653{
654 int count, i, rc = 0;
655 acpi_status status;
656 struct acpi_table_header *pcct_tbl;
657 struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
658
659 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
660 if (ACPI_FAILURE(status) || !pcct_tbl)
661 return -ENODEV;
662
663 /* Set up the subtable handlers */
664 for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
665 i < ACPI_PCCT_TYPE_RESERVED; i++) {
666 proc[i].id = i;
667 proc[i].count = 0;
668 proc[i].handler = parse_pcc_subspace;
669 }
670
671 count = acpi_table_parse_entries_array(ACPI_SIG_PCCT,
672 sizeof(struct acpi_table_pcct), proc,
673 ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES);
674 if (count <= 0 || count > MAX_PCC_SUBSPACES) {
675 if (count < 0)
676 pr_warn("Error parsing PCC subspaces from PCCT\n");
677 else
678 pr_warn("Invalid PCCT: %d PCC subspaces\n", count);
679
680 rc = -EINVAL;
681 } else {
682 pcc_chan_count = count;
683 }
684
685 acpi_put_table(pcct_tbl);
686
687 return rc;
688}
689
690/**
691 * pcc_mbox_probe - Called when we find a match for the
692 * PCCT platform device. This is purely used to represent
693 * the PCCT as a virtual device for registering with the
694 * generic Mailbox framework.
695 *
696 * @pdev: Pointer to platform device returned when a match
697 * is found.
698 *
699 * Return: 0 for Success, else errno.
700 */
701static int pcc_mbox_probe(struct platform_device *pdev)
702{
703 struct device *dev = &pdev->dev;
704 struct mbox_controller *pcc_mbox_ctrl;
705 struct mbox_chan *pcc_mbox_channels;
706 struct acpi_table_header *pcct_tbl;
707 struct acpi_subtable_header *pcct_entry;
708 struct acpi_table_pcct *acpi_pcct_tbl;
709 acpi_status status = AE_OK;
710 int i, rc, count = pcc_chan_count;
711
712 /* Search for PCCT */
713 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
714
715 if (ACPI_FAILURE(status) || !pcct_tbl)
716 return -ENODEV;
717
718 pcc_mbox_channels = devm_kcalloc(dev, count, sizeof(*pcc_mbox_channels),
719 GFP_KERNEL);
720 if (!pcc_mbox_channels) {
721 rc = -ENOMEM;
722 goto err;
723 }
724
725 chan_info = devm_kcalloc(dev, count, sizeof(*chan_info), GFP_KERNEL);
726 if (!chan_info) {
727 rc = -ENOMEM;
728 goto err;
729 }
730
731 pcc_mbox_ctrl = devm_kzalloc(dev, sizeof(*pcc_mbox_ctrl), GFP_KERNEL);
732 if (!pcc_mbox_ctrl) {
733 rc = -ENOMEM;
734 goto err;
735 }
736
737 /* Point to the first PCC subspace entry */
738 pcct_entry = (struct acpi_subtable_header *) (
739 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
740
741 acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
742 if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
743 pcc_mbox_ctrl->txdone_irq = true;
744
745 for (i = 0; i < count; i++) {
746 struct pcc_chan_info *pchan = chan_info + i;
747
748 pcc_mbox_channels[i].con_priv = pchan;
749 pchan->chan.mchan = &pcc_mbox_channels[i];
750
751 if (pcct_entry->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE &&
752 !pcc_mbox_ctrl->txdone_irq) {
753 pr_err("Platform Interrupt flag must be set to 1");
754 rc = -EINVAL;
755 goto err;
756 }
757
758 if (pcc_mbox_ctrl->txdone_irq) {
759 rc = pcc_parse_subspace_irq(pchan, pcct_entry);
760 if (rc < 0)
761 goto err;
762 }
763 rc = pcc_parse_subspace_db_reg(pchan, pcct_entry);
764 if (rc < 0)
765 goto err;
766
767 pcc_parse_subspace_shmem(pchan, pcct_entry);
768
769 pchan->type = pcct_entry->type;
770 pcct_entry = (struct acpi_subtable_header *)
771 ((unsigned long) pcct_entry + pcct_entry->length);
772 }
773
774 pcc_mbox_ctrl->num_chans = count;
775
776 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl->num_chans);
777
778 pcc_mbox_ctrl->chans = pcc_mbox_channels;
779 pcc_mbox_ctrl->ops = &pcc_chan_ops;
780 pcc_mbox_ctrl->dev = dev;
781
782 pr_info("Registering PCC driver as Mailbox controller\n");
783 rc = mbox_controller_register(pcc_mbox_ctrl);
784 if (rc)
785 pr_err("Err registering PCC as Mailbox controller: %d\n", rc);
786 else
787 return 0;
788err:
789 acpi_put_table(pcct_tbl);
790 return rc;
791}
792
793static struct platform_driver pcc_mbox_driver = {
794 .probe = pcc_mbox_probe,
795 .driver = {
796 .name = "PCCT",
797 },
798};
799
800static int __init pcc_init(void)
801{
802 int ret;
803 struct platform_device *pcc_pdev;
804
805 if (acpi_disabled)
806 return -ENODEV;
807
808 /* Check if PCC support is available. */
809 ret = acpi_pcc_probe();
810
811 if (ret) {
812 pr_debug("ACPI PCC probe failed.\n");
813 return -ENODEV;
814 }
815
816 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
817 pcc_mbox_probe, NULL, 0, NULL, 0);
818
819 if (IS_ERR(pcc_pdev)) {
820 pr_debug("Err creating PCC platform bundle\n");
821 pcc_chan_count = 0;
822 return PTR_ERR(pcc_pdev);
823 }
824
825 return 0;
826}
827
828/*
829 * Make PCC init postcore so that users of this mailbox
830 * such as the ACPI Processor driver have it available
831 * at their init.
832 */
833postcore_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);