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