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