aboutsummaryrefslogtreecommitdiff
path: root/drivers/mailbox/pcc.c
blob: ef9ecd1f595880f197140103759b1c2a2a3874bd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	Copyright (C) 2014 Linaro Ltd.
 *	Author:	Ashwin Chaugule <ashwin.chaugule@linaro.org>
 *
 *  PCC (Platform Communication Channel) is defined in the ACPI 5.0+
 *  specification. It is a mailbox like mechanism to allow clients
 *  such as CPPC (Collaborative Processor Performance Control), RAS
 *  (Reliability, Availability and Serviceability) and MPST (Memory
 *  Node Power State Table) to talk to the platform (e.g. BMC) through
 *  shared memory regions as defined in the PCC table entries. The PCC
 *  specification supports a Doorbell mechanism for the PCC clients
 *  to notify the platform about new data. This Doorbell information
 *  is also specified in each PCC table entry.
 *
 *  Typical high level flow of operation is:
 *
 *  PCC Reads:
 *  * Client tries to acquire a channel lock.
 *  * After it is acquired it writes READ cmd in communication region cmd
 *		address.
 *  * Client issues mbox_send_message() which rings the PCC doorbell
 *		for its PCC channel.
 *  * If command completes, then client has control over channel and
 *		it can proceed with its reads.
 *  * Client releases lock.
 *
 *  PCC Writes:
 *  * Client tries to acquire channel lock.
 *  * Client writes to its communication region after it acquires a
 *		channel lock.
 *  * Client writes WRITE cmd in communication region cmd address.
 *  * Client issues mbox_send_message() which rings the PCC doorbell
 *		for its PCC channel.
 *  * If command completes, then writes have succeded and it can release
 *		the channel lock.
 *
 *  There is a Nominal latency defined for each channel which indicates
 *  how long to wait until a command completes. If command is not complete
 *  the client needs to retry or assume failure.
 *
 *	For more details about PCC, please see the ACPI specification from
 *  http://www.uefi.org/ACPIv5.1 Section 14.
 *
 *  This file implements PCC as a Mailbox controller and allows for PCC
 *  clients to be implemented as its Mailbox Client Channels.
 */

#include <linux/acpi.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/platform_device.h>
#include <linux/mailbox_controller.h>
#include <linux/mailbox_client.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <acpi/pcc.h>

#include "mailbox.h"

#define MBOX_IRQ_NAME		"pcc-mbox"

static struct mbox_chan *pcc_mbox_channels;

/* Array of cached virtual address for doorbell registers */
static void __iomem **pcc_doorbell_vaddr;
/* Array of cached virtual address for doorbell ack registers */
static void __iomem **pcc_doorbell_ack_vaddr;
/* Array of doorbell interrupts */
static int *pcc_doorbell_irq;

static struct mbox_controller pcc_mbox_ctrl = {};
/**
 * get_pcc_channel - Given a PCC subspace idx, get
 *	the respective mbox_channel.
 * @id: PCC subspace index.
 *
 * Return: ERR_PTR(errno) if error, else pointer
 *	to mbox channel.
 */
static struct mbox_chan *get_pcc_channel(int id)
{
	if (id < 0 || id >= pcc_mbox_ctrl.num_chans)
		return ERR_PTR(-ENOENT);

	return &pcc_mbox_channels[id];
}

/*
 * PCC can be used with perf critical drivers such as CPPC
 * So it makes sense to locally cache the virtual address and
 * use it to read/write to PCC registers such as doorbell register
 *
 * The below read_register and write_registers are used to read and
 * write from perf critical registers such as PCC doorbell register
 */
static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
{
	int ret_val = 0;

	switch (bit_width) {
	case 8:
		*val = readb(vaddr);
		break;
	case 16:
		*val = readw(vaddr);
		break;
	case 32:
		*val = readl(vaddr);
		break;
	case 64:
		*val = readq(vaddr);
		break;
	default:
		pr_debug("Error: Cannot read register of %u bit width",
			bit_width);
		ret_val = -EFAULT;
		break;
	}
	return ret_val;
}

static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
{
	int ret_val = 0;

	switch (bit_width) {
	case 8:
		writeb(val, vaddr);
		break;
	case 16:
		writew(val, vaddr);
		break;
	case 32:
		writel(val, vaddr);
		break;
	case 64:
		writeq(val, vaddr);
		break;
	default:
		pr_debug("Error: Cannot write register of %u bit width",
			bit_width);
		ret_val = -EFAULT;
		break;
	}
	return ret_val;
}

/**
 * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number
 * @interrupt: GSI number.
 * @flags: interrupt flags
 *
 * Returns: a valid linux IRQ number on success
 *		0 or -EINVAL on failure
 */
static int pcc_map_interrupt(u32 interrupt, u32 flags)
{
	int trigger, polarity;

	if (!interrupt)
		return 0;

	trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
			: ACPI_LEVEL_SENSITIVE;

	polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
			: ACPI_ACTIVE_HIGH;

	return acpi_register_gsi(NULL, interrupt, trigger, polarity);
}

/**
 * pcc_mbox_irq - PCC mailbox interrupt handler
 */
static irqreturn_t pcc_mbox_irq(int irq, void *p)
{
	struct acpi_generic_address *doorbell_ack;
	struct acpi_pcct_hw_reduced *pcct_ss;
	struct mbox_chan *chan = p;
	u64 doorbell_ack_preserve;
	u64 doorbell_ack_write;
	u64 doorbell_ack_val;
	int ret;

	pcct_ss = chan->con_priv;

	mbox_chan_received_data(chan, NULL);

	if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
		struct acpi_pcct_hw_reduced_type2 *pcct2_ss = chan->con_priv;
		u32 id = chan - pcc_mbox_channels;

		doorbell_ack = &pcct2_ss->platform_ack_register;
		doorbell_ack_preserve = pcct2_ss->ack_preserve_mask;
		doorbell_ack_write = pcct2_ss->ack_write_mask;

		ret = read_register(pcc_doorbell_ack_vaddr[id],
				    &doorbell_ack_val,
				    doorbell_ack->bit_width);
		if (ret)
			return IRQ_NONE;

		ret = write_register(pcc_doorbell_ack_vaddr[id],
				     (doorbell_ack_val & doorbell_ack_preserve)
					| doorbell_ack_write,
				     doorbell_ack->bit_width);
		if (ret)
			return IRQ_NONE;
	}

	return IRQ_HANDLED;
}

/**
 * pcc_mbox_request_channel - PCC clients call this function to
 *		request a pointer to their PCC subspace, from which they
 *		can get the details of communicating with the remote.
 * @cl: Pointer to Mailbox client, so we know where to bind the
 *		Channel.
 * @subspace_id: The PCC Subspace index as parsed in the PCC client
 *		ACPI package. This is used to lookup the array of PCC
 *		subspaces as parsed by the PCC Mailbox controller.
 *
 * Return: Pointer to the Mailbox Channel if successful or
 *		ERR_PTR.
 */
struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
		int subspace_id)
{
	struct device *dev = pcc_mbox_ctrl.dev;
	struct mbox_chan *chan;
	unsigned long flags;

	/*
	 * Each PCC Subspace is a Mailbox Channel.
	 * The PCC Clients get their PCC Subspace ID
	 * from their own tables and pass it here.
	 * This returns a pointer to the PCC subspace
	 * for the Client to operate on.
	 */
	chan = get_pcc_channel(subspace_id);

	if (IS_ERR(chan) || chan->cl) {
		dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
		return ERR_PTR(-EBUSY);
	}

	spin_lock_irqsave(&chan->lock, flags);
	chan->msg_free = 0;
	chan->msg_count = 0;
	chan->active_req = NULL;
	chan->cl = cl;
	init_completion(&chan->tx_complete);

	if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
		chan->txdone_method = TXDONE_BY_ACK;

	spin_unlock_irqrestore(&chan->lock, flags);

	if (pcc_doorbell_irq[subspace_id] > 0) {
		int rc;

		rc = devm_request_irq(dev, pcc_doorbell_irq[subspace_id],
				      pcc_mbox_irq, 0, MBOX_IRQ_NAME, chan);
		if (unlikely(rc)) {
			dev_err(dev, "failed to register PCC interrupt %d\n",
				pcc_doorbell_irq[subspace_id]);
			pcc_mbox_free_channel(chan);
			chan = ERR_PTR(rc);
		}
	}

	return chan;
}
EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);

/**
 * pcc_mbox_free_channel - Clients call this to free their Channel.
 *
 * @chan: Pointer to the mailbox channel as returned by
 *		pcc_mbox_request_channel()
 */
void pcc_mbox_free_channel(struct mbox_chan *chan)
{
	u32 id = chan - pcc_mbox_channels;
	unsigned long flags;

	if (!chan || !chan->cl)
		return;

	if (id >= pcc_mbox_ctrl.num_chans) {
		pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n");
		return;
	}

	if (pcc_doorbell_irq[id] > 0)
		devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan);

	spin_lock_irqsave(&chan->lock, flags);
	chan->cl = NULL;
	chan->active_req = NULL;
	if (chan->txdone_method == TXDONE_BY_ACK)
		chan->txdone_method = TXDONE_BY_POLL;

	spin_unlock_irqrestore(&chan->lock, flags);
}
EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);

/**
 * pcc_send_data - Called from Mailbox Controller code. Used
 *		here only to ring the channel doorbell. The PCC client
 *		specific read/write is done in the client driver in
 *		order to maintain atomicity over PCC channel once
 *		OS has control over it. See above for flow of operations.
 * @chan: Pointer to Mailbox channel over which to send data.
 * @data: Client specific data written over channel. Used here
 *		only for debug after PCC transaction completes.
 *
 * Return: Err if something failed else 0 for success.
 */
static int pcc_send_data(struct mbox_chan *chan, void *data)
{
	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
	struct acpi_generic_address *doorbell;
	u64 doorbell_preserve;
	u64 doorbell_val;
	u64 doorbell_write;
	u32 id = chan - pcc_mbox_channels;
	int ret = 0;

	if (id >= pcc_mbox_ctrl.num_chans) {
		pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
		return -ENOENT;
	}

	doorbell = &pcct_ss->doorbell_register;
	doorbell_preserve = pcct_ss->preserve_mask;
	doorbell_write = pcct_ss->write_mask;

	/* Sync notification from OS to Platform. */
	if (pcc_doorbell_vaddr[id]) {
		ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
			doorbell->bit_width);
		if (ret)
			return ret;
		ret = write_register(pcc_doorbell_vaddr[id],
			(doorbell_val & doorbell_preserve) | doorbell_write,
			doorbell->bit_width);
	} else {
		ret = acpi_read(&doorbell_val, doorbell);
		if (ret)
			return ret;
		ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
			doorbell);
	}
	return ret;
}

static const struct mbox_chan_ops pcc_chan_ops = {
	.send_data = pcc_send_data,
};

/**
 * parse_pcc_subspaces -- Count PCC subspaces defined
 * @header: Pointer to the ACPI subtable header under the PCCT.
 * @end: End of subtable entry.
 *
 * Return: If we find a PCC subspace entry of a valid type, return 0.
 *	Otherwise, return -EINVAL.
 *
 * This gets called for each entry in the PCC table.
 */
static int parse_pcc_subspace(union acpi_subtable_headers *header,
		const unsigned long end)
{
	struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;

	if (ss->header.type < ACPI_PCCT_TYPE_RESERVED)
		return 0;

	return -EINVAL;
}

/**
 * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
 *		There should be one entry per PCC client.
 * @id: PCC subspace index.
 * @pcct_ss: Pointer to the ACPI subtable header under the PCCT.
 *
 * Return: 0 for Success, else errno.
 *
 * This gets called for each entry in the PCC table.
 */
static int pcc_parse_subspace_irq(int id,
				  struct acpi_pcct_hw_reduced *pcct_ss)
{
	pcc_doorbell_irq[id] = pcc_map_interrupt(pcct_ss->platform_interrupt,
						 (u32)pcct_ss->flags);
	if (pcc_doorbell_irq[id] <= 0) {
		pr_err("PCC GSI %d not registered\n",
		       pcct_ss->platform_interrupt);
		return -EINVAL;
	}

	if (pcct_ss->header.type
		== ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
		struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;

		pcc_doorbell_ack_vaddr[id] = acpi_os_ioremap(
				pcct2_ss->platform_ack_register.address,
				pcct2_ss->platform_ack_register.bit_width / 8);
		if (!pcc_doorbell_ack_vaddr[id]) {
			pr_err("Failed to ioremap PCC ACK register\n");
			return -ENOMEM;
		}
	}

	return 0;
}

/**
 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
 *
 * Return: 0 for Success, else errno.
 */
static int __init acpi_pcc_probe(void)
{
	struct acpi_table_header *pcct_tbl;
	struct acpi_subtable_header *pcct_entry;
	struct acpi_table_pcct *acpi_pcct_tbl;
	struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
	int count, i, rc;
	acpi_status status = AE_OK;

	/* Search for PCCT */
	status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);

	if (ACPI_FAILURE(status) || !pcct_tbl)
		return -ENODEV;

	/* Set up the subtable handlers */
	for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
	     i < ACPI_PCCT_TYPE_RESERVED; i++) {
		proc[i].id = i;
		proc[i].count = 0;
		proc[i].handler = parse_pcc_subspace;
	}

	count = acpi_table_parse_entries_array(ACPI_SIG_PCCT,
			sizeof(struct acpi_table_pcct), proc,
			ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES);
	if (count <= 0 || count > MAX_PCC_SUBSPACES) {
		if (count < 0)
			pr_warn("Error parsing PCC subspaces from PCCT\n");
		else
			pr_warn("Invalid PCCT: %d PCC subspaces\n", count);

		rc = -EINVAL;
		goto err_put_pcct;
	}

	pcc_mbox_channels = kcalloc(count, sizeof(struct mbox_chan),
				    GFP_KERNEL);
	if (!pcc_mbox_channels) {
		pr_err("Could not allocate space for PCC mbox channels\n");
		rc = -ENOMEM;
		goto err_put_pcct;
	}

	pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
	if (!pcc_doorbell_vaddr) {
		rc = -ENOMEM;
		goto err_free_mbox;
	}

	pcc_doorbell_ack_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
	if (!pcc_doorbell_ack_vaddr) {
		rc = -ENOMEM;
		goto err_free_db_vaddr;
	}

	pcc_doorbell_irq = kcalloc(count, sizeof(int), GFP_KERNEL);
	if (!pcc_doorbell_irq) {
		rc = -ENOMEM;
		goto err_free_db_ack_vaddr;
	}

	/* Point to the first PCC subspace entry */
	pcct_entry = (struct acpi_subtable_header *) (
		(unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));

	acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
	if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
		pcc_mbox_ctrl.txdone_irq = true;

	for (i = 0; i < count; i++) {
		struct acpi_generic_address *db_reg;
		struct acpi_pcct_subspace *pcct_ss;
		pcc_mbox_channels[i].con_priv = pcct_entry;

		if (pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
		    pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
			struct acpi_pcct_hw_reduced *pcct_hrss;

			pcct_hrss = (struct acpi_pcct_hw_reduced *) pcct_entry;

			if (pcc_mbox_ctrl.txdone_irq) {
				rc = pcc_parse_subspace_irq(i, pcct_hrss);
				if (rc < 0)
					goto err;
			}
		}
		pcct_ss = (struct acpi_pcct_subspace *) pcct_entry;

		/* If doorbell is in system memory cache the virt address */
		db_reg = &pcct_ss->doorbell_register;
		if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
			pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
							db_reg->bit_width/8);
		pcct_entry = (struct acpi_subtable_header *)
			((unsigned long) pcct_entry + pcct_entry->length);
	}

	pcc_mbox_ctrl.num_chans = count;

	pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);

	return 0;

err:
	kfree(pcc_doorbell_irq);
err_free_db_ack_vaddr:
	kfree(pcc_doorbell_ack_vaddr);
err_free_db_vaddr:
	kfree(pcc_doorbell_vaddr);
err_free_mbox:
	kfree(pcc_mbox_channels);
err_put_pcct:
	acpi_put_table(pcct_tbl);
	return rc;
}

/**
 * pcc_mbox_probe - Called when we find a match for the
 *	PCCT platform device. This is purely used to represent
 *	the PCCT as a virtual device for registering with the
 *	generic Mailbox framework.
 *
 * @pdev: Pointer to platform device returned when a match
 *	is found.
 *
 *	Return: 0 for Success, else errno.
 */
static int pcc_mbox_probe(struct platform_device *pdev)
{
	int ret = 0;

	pcc_mbox_ctrl.chans = pcc_mbox_channels;
	pcc_mbox_ctrl.ops = &pcc_chan_ops;
	pcc_mbox_ctrl.dev = &pdev->dev;

	pr_info("Registering PCC driver as Mailbox controller\n");
	ret = mbox_controller_register(&pcc_mbox_ctrl);

	if (ret) {
		pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
		ret = -ENODEV;
	}

	return ret;
}

static struct platform_driver pcc_mbox_driver = {
	.probe = pcc_mbox_probe,
	.driver = {
		.name = "PCCT",
		.owner = THIS_MODULE,
	},
};

static int __init pcc_init(void)
{
	int ret;
	struct platform_device *pcc_pdev;

	if (acpi_disabled)
		return -ENODEV;

	/* Check if PCC support is available. */
	ret = acpi_pcc_probe();

	if (ret) {
		pr_debug("ACPI PCC probe failed.\n");
		return -ENODEV;
	}

	pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
			pcc_mbox_probe, NULL, 0, NULL, 0);

	if (IS_ERR(pcc_pdev)) {
		pr_debug("Err creating PCC platform bundle\n");
		return PTR_ERR(pcc_pdev);
	}

	return 0;
}

/*
 * Make PCC init postcore so that users of this mailbox
 * such as the ACPI Processor driver have it available
 * at their init.
 */
postcore_initcall(pcc_init);