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