1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright (C) 2014 Linaro Ltd.
4 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
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.
16 * Typical high level flow of operation is:
19 * * Client tries to acquire a channel lock.
20 * * After it is acquired it writes READ cmd in communication region cmd
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.
29 * * Client tries to acquire channel lock.
30 * * Client writes to its communication region after it acquires a
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
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.
42 * For more details about PCC, please see the ACPI specification from
43 * http://www.uefi.org/ACPIv5.1 Section 14.
45 * This file implements PCC as a Mailbox controller and allows for PCC
46 * clients to be implemented as its Mailbox Client Channels.
49 #include <linux/acpi.h>
50 #include <linux/delay.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>
64 #define MBOX_IRQ_NAME "pcc-mbox"
67 * struct pcc_chan_reg - PCC register bundle
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
77 struct acpi_generic_address *gas;
84 * struct pcc_chan_info - PCC channel specific information
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
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
95 struct 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;
105 #define to_pcc_chan_info(c) container_of(c, struct pcc_chan_info, chan)
106 static struct pcc_chan_info *chan_info;
107 static int pcc_chan_count;
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
114 * The below read_register and write_registers are used to read and
115 * write from perf critical registers such as PCC doorbell register
117 static void read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
135 static void write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
153 static int pcc_chan_reg_read(struct pcc_chan_reg *reg, u64 *val)
163 read_register(reg->vaddr, val, reg->gas->bit_width);
165 ret = acpi_read(val, reg->gas);
170 static int pcc_chan_reg_write(struct pcc_chan_reg *reg, u64 val)
178 write_register(reg->vaddr, val, reg->gas->bit_width);
180 ret = acpi_write(val, reg->gas);
185 static int pcc_chan_reg_read_modify_write(struct pcc_chan_reg *reg)
190 ret = pcc_chan_reg_read(reg, &val);
194 val &= reg->preserve_mask;
195 val |= reg->set_mask;
197 return pcc_chan_reg_write(reg, val);
201 * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number
202 * @interrupt: GSI number.
203 * @flags: interrupt flags
205 * Returns: a valid linux IRQ number on success
206 * 0 or -EINVAL on failure
208 static int pcc_map_interrupt(u32 interrupt, u32 flags)
210 int trigger, polarity;
215 trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
216 : ACPI_LEVEL_SENSITIVE;
218 polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
221 return acpi_register_gsi(NULL, interrupt, trigger, polarity);
225 * pcc_mbox_irq - PCC mailbox interrupt handler
226 * @irq: interrupt number
227 * @p: data/cookie passed from the caller to identify the channel
229 * Returns: IRQ_HANDLED if interrupt is handled or IRQ_NONE if not
231 static irqreturn_t pcc_mbox_irq(int irq, void *p)
233 struct pcc_chan_info *pchan;
234 struct mbox_chan *chan = p;
238 pchan = chan->con_priv;
240 ret = pcc_chan_reg_read(&pchan->cmd_complete, &val);
244 val &= pchan->cmd_complete.status_mask;
248 ret = pcc_chan_reg_read(&pchan->error, &val);
251 val &= pchan->error.status_mask;
253 val &= ~pchan->error.status_mask;
254 pcc_chan_reg_write(&pchan->error, val);
258 if (pcc_chan_reg_read_modify_write(&pchan->plat_irq_ack))
261 mbox_chan_received_data(chan, NULL);
267 * pcc_mbox_request_channel - PCC clients call this function to
268 * request a pointer to their PCC subspace, from which they
269 * can get the details of communicating with the remote.
270 * @cl: Pointer to Mailbox client, so we know where to bind the
272 * @subspace_id: The PCC Subspace index as parsed in the PCC client
273 * ACPI package. This is used to lookup the array of PCC
274 * subspaces as parsed by the PCC Mailbox controller.
276 * Return: Pointer to the PCC Mailbox Channel if successful or ERR_PTR.
278 struct pcc_mbox_chan *
279 pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
281 struct pcc_chan_info *pchan;
282 struct mbox_chan *chan;
286 if (subspace_id < 0 || subspace_id >= pcc_chan_count)
287 return ERR_PTR(-ENOENT);
289 pchan = chan_info + subspace_id;
290 chan = pchan->chan.mchan;
291 if (IS_ERR(chan) || chan->cl) {
292 dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
293 return ERR_PTR(-EBUSY);
295 dev = chan->mbox->dev;
297 spin_lock_irqsave(&chan->lock, flags);
300 chan->active_req = NULL;
302 init_completion(&chan->tx_complete);
304 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
305 chan->txdone_method = TXDONE_BY_ACK;
307 spin_unlock_irqrestore(&chan->lock, flags);
309 if (pchan->plat_irq > 0) {
312 rc = devm_request_irq(dev, pchan->plat_irq, pcc_mbox_irq, 0,
313 MBOX_IRQ_NAME, chan);
315 dev_err(dev, "failed to register PCC interrupt %d\n",
317 pcc_mbox_free_channel(&pchan->chan);
324 EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
327 * pcc_mbox_free_channel - Clients call this to free their Channel.
329 * @pchan: Pointer to the PCC mailbox channel as returned by
330 * pcc_mbox_request_channel()
332 void pcc_mbox_free_channel(struct pcc_mbox_chan *pchan)
334 struct pcc_chan_info *pchan_info = to_pcc_chan_info(pchan);
335 struct mbox_chan *chan = pchan->mchan;
338 if (!chan || !chan->cl)
341 if (pchan_info->plat_irq > 0)
342 devm_free_irq(chan->mbox->dev, pchan_info->plat_irq, chan);
344 spin_lock_irqsave(&chan->lock, flags);
346 chan->active_req = NULL;
347 if (chan->txdone_method == TXDONE_BY_ACK)
348 chan->txdone_method = TXDONE_BY_POLL;
350 spin_unlock_irqrestore(&chan->lock, flags);
352 EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
355 * pcc_send_data - Called from Mailbox Controller code. Used
356 * here only to ring the channel doorbell. The PCC client
357 * specific read/write is done in the client driver in
358 * order to maintain atomicity over PCC channel once
359 * OS has control over it. See above for flow of operations.
360 * @chan: Pointer to Mailbox channel over which to send data.
361 * @data: Client specific data written over channel. Used here
362 * only for debug after PCC transaction completes.
364 * Return: Err if something failed else 0 for success.
366 static int pcc_send_data(struct mbox_chan *chan, void *data)
369 struct pcc_chan_info *pchan = chan->con_priv;
371 ret = pcc_chan_reg_read_modify_write(&pchan->cmd_update);
375 return pcc_chan_reg_read_modify_write(&pchan->db);
378 static const struct mbox_chan_ops pcc_chan_ops = {
379 .send_data = pcc_send_data,
383 * parse_pcc_subspace - Count PCC subspaces defined
384 * @header: Pointer to the ACPI subtable header under the PCCT.
385 * @end: End of subtable entry.
387 * Return: If we find a PCC subspace entry of a valid type, return 0.
388 * Otherwise, return -EINVAL.
390 * This gets called for each entry in the PCC table.
392 static int parse_pcc_subspace(union acpi_subtable_headers *header,
393 const unsigned long end)
395 struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;
397 if (ss->header.type < ACPI_PCCT_TYPE_RESERVED)
404 pcc_chan_reg_init(struct pcc_chan_reg *reg, struct acpi_generic_address *gas,
405 u64 preserve_mask, u64 set_mask, u64 status_mask, char *name)
407 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
408 if (!(gas->bit_width >= 8 && gas->bit_width <= 64 &&
409 is_power_of_2(gas->bit_width))) {
410 pr_err("Error: Cannot access register of %u bit width",
415 reg->vaddr = acpi_os_ioremap(gas->address, gas->bit_width / 8);
417 pr_err("Failed to ioremap PCC %s register\n", name);
422 reg->preserve_mask = preserve_mask;
423 reg->set_mask = set_mask;
424 reg->status_mask = status_mask;
429 * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
431 * @pchan: Pointer to the PCC channel info structure.
432 * @pcct_entry: Pointer to the ACPI subtable header.
434 * Return: 0 for Success, else errno.
436 * There should be one entry per PCC channel. This gets called for each
437 * entry in the PCC table. This uses PCCY Type1 structure for all applicable
438 * types(Type 1-4) to fetch irq
440 static int pcc_parse_subspace_irq(struct pcc_chan_info *pchan,
441 struct acpi_subtable_header *pcct_entry)
444 struct acpi_pcct_hw_reduced *pcct_ss;
446 if (pcct_entry->type < ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
447 pcct_entry->type > ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
450 pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
451 pchan->plat_irq = pcc_map_interrupt(pcct_ss->platform_interrupt,
452 (u32)pcct_ss->flags);
453 if (pchan->plat_irq <= 0) {
454 pr_err("PCC GSI %d not registered\n",
455 pcct_ss->platform_interrupt);
459 if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
460 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
462 ret = pcc_chan_reg_init(&pchan->plat_irq_ack,
463 &pcct2_ss->platform_ack_register,
464 pcct2_ss->ack_preserve_mask,
465 pcct2_ss->ack_write_mask, 0,
468 } else if (pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE ||
469 pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE) {
470 struct acpi_pcct_ext_pcc_master *pcct_ext = (void *)pcct_ss;
472 ret = pcc_chan_reg_init(&pchan->plat_irq_ack,
473 &pcct_ext->platform_ack_register,
474 pcct_ext->ack_preserve_mask,
475 pcct_ext->ack_set_mask, 0,
483 * pcc_parse_subspace_db_reg - Parse the PCC doorbell register
485 * @pchan: Pointer to the PCC channel info structure.
486 * @pcct_entry: Pointer to the ACPI subtable header.
488 * Return: 0 for Success, else errno.
490 static int pcc_parse_subspace_db_reg(struct pcc_chan_info *pchan,
491 struct acpi_subtable_header *pcct_entry)
495 if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
496 struct acpi_pcct_subspace *pcct_ss;
498 pcct_ss = (struct acpi_pcct_subspace *)pcct_entry;
500 ret = pcc_chan_reg_init(&pchan->db,
501 &pcct_ss->doorbell_register,
502 pcct_ss->preserve_mask,
503 pcct_ss->write_mask, 0, "Doorbell");
506 struct acpi_pcct_ext_pcc_master *pcct_ext;
508 pcct_ext = (struct acpi_pcct_ext_pcc_master *)pcct_entry;
510 ret = pcc_chan_reg_init(&pchan->db,
511 &pcct_ext->doorbell_register,
512 pcct_ext->preserve_mask,
513 pcct_ext->write_mask, 0, "Doorbell");
517 ret = pcc_chan_reg_init(&pchan->cmd_complete,
518 &pcct_ext->cmd_complete_register,
519 0, 0, pcct_ext->cmd_complete_mask,
520 "Command Complete Check");
524 ret = pcc_chan_reg_init(&pchan->cmd_update,
525 &pcct_ext->cmd_update_register,
526 pcct_ext->cmd_update_preserve_mask,
527 pcct_ext->cmd_update_set_mask, 0,
528 "Command Complete Update");
532 ret = pcc_chan_reg_init(&pchan->error,
533 &pcct_ext->error_status_register,
534 0, 0, pcct_ext->error_status_mask,
541 * pcc_parse_subspace_shmem - Parse the PCC Shared Memory Region information
543 * @pchan: Pointer to the PCC channel info structure.
544 * @pcct_entry: Pointer to the ACPI subtable header.
547 static void pcc_parse_subspace_shmem(struct pcc_chan_info *pchan,
548 struct acpi_subtable_header *pcct_entry)
550 if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
551 struct acpi_pcct_subspace *pcct_ss =
552 (struct acpi_pcct_subspace *)pcct_entry;
554 pchan->chan.shmem_base_addr = pcct_ss->base_address;
555 pchan->chan.shmem_size = pcct_ss->length;
556 pchan->chan.latency = pcct_ss->latency;
557 pchan->chan.max_access_rate = pcct_ss->max_access_rate;
558 pchan->chan.min_turnaround_time = pcct_ss->min_turnaround_time;
560 struct acpi_pcct_ext_pcc_master *pcct_ext =
561 (struct acpi_pcct_ext_pcc_master *)pcct_entry;
563 pchan->chan.shmem_base_addr = pcct_ext->base_address;
564 pchan->chan.shmem_size = pcct_ext->length;
565 pchan->chan.latency = pcct_ext->latency;
566 pchan->chan.max_access_rate = pcct_ext->max_access_rate;
567 pchan->chan.min_turnaround_time = pcct_ext->min_turnaround_time;
572 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
574 * Return: 0 for Success, else errno.
576 static int __init acpi_pcc_probe(void)
578 int count, i, rc = 0;
580 struct acpi_table_header *pcct_tbl;
581 struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
583 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
584 if (ACPI_FAILURE(status) || !pcct_tbl)
587 /* Set up the subtable handlers */
588 for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
589 i < ACPI_PCCT_TYPE_RESERVED; i++) {
592 proc[i].handler = parse_pcc_subspace;
595 count = acpi_table_parse_entries_array(ACPI_SIG_PCCT,
596 sizeof(struct acpi_table_pcct), proc,
597 ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES);
598 if (count <= 0 || count > MAX_PCC_SUBSPACES) {
600 pr_warn("Error parsing PCC subspaces from PCCT\n");
602 pr_warn("Invalid PCCT: %d PCC subspaces\n", count);
606 pcc_chan_count = count;
609 acpi_put_table(pcct_tbl);
615 * pcc_mbox_probe - Called when we find a match for the
616 * PCCT platform device. This is purely used to represent
617 * the PCCT as a virtual device for registering with the
618 * generic Mailbox framework.
620 * @pdev: Pointer to platform device returned when a match
623 * Return: 0 for Success, else errno.
625 static int pcc_mbox_probe(struct platform_device *pdev)
627 struct device *dev = &pdev->dev;
628 struct mbox_controller *pcc_mbox_ctrl;
629 struct mbox_chan *pcc_mbox_channels;
630 struct acpi_table_header *pcct_tbl;
631 struct acpi_subtable_header *pcct_entry;
632 struct acpi_table_pcct *acpi_pcct_tbl;
633 acpi_status status = AE_OK;
634 int i, rc, count = pcc_chan_count;
636 /* Search for PCCT */
637 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
639 if (ACPI_FAILURE(status) || !pcct_tbl)
642 pcc_mbox_channels = devm_kcalloc(dev, count, sizeof(*pcc_mbox_channels),
644 if (!pcc_mbox_channels) {
649 chan_info = devm_kcalloc(dev, count, sizeof(*chan_info), GFP_KERNEL);
655 pcc_mbox_ctrl = devm_kmalloc(dev, sizeof(*pcc_mbox_ctrl), GFP_KERNEL);
656 if (!pcc_mbox_ctrl) {
661 /* Point to the first PCC subspace entry */
662 pcct_entry = (struct acpi_subtable_header *) (
663 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
665 acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
666 if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
667 pcc_mbox_ctrl->txdone_irq = true;
669 for (i = 0; i < count; i++) {
670 struct pcc_chan_info *pchan = chan_info + i;
672 pcc_mbox_channels[i].con_priv = pchan;
673 pchan->chan.mchan = &pcc_mbox_channels[i];
675 if (pcct_entry->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE &&
676 !pcc_mbox_ctrl->txdone_irq) {
677 pr_err("Plaform Interrupt flag must be set to 1");
682 if (pcc_mbox_ctrl->txdone_irq) {
683 rc = pcc_parse_subspace_irq(pchan, pcct_entry);
687 rc = pcc_parse_subspace_db_reg(pchan, pcct_entry);
691 pcc_parse_subspace_shmem(pchan, pcct_entry);
693 pcct_entry = (struct acpi_subtable_header *)
694 ((unsigned long) pcct_entry + pcct_entry->length);
697 pcc_mbox_ctrl->num_chans = count;
699 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl->num_chans);
701 pcc_mbox_ctrl->chans = pcc_mbox_channels;
702 pcc_mbox_ctrl->ops = &pcc_chan_ops;
703 pcc_mbox_ctrl->dev = dev;
705 pr_info("Registering PCC driver as Mailbox controller\n");
706 rc = mbox_controller_register(pcc_mbox_ctrl);
708 pr_err("Err registering PCC as Mailbox controller: %d\n", rc);
712 acpi_put_table(pcct_tbl);
716 static struct platform_driver pcc_mbox_driver = {
717 .probe = pcc_mbox_probe,
723 static int __init pcc_init(void)
726 struct platform_device *pcc_pdev;
731 /* Check if PCC support is available. */
732 ret = acpi_pcc_probe();
735 pr_debug("ACPI PCC probe failed.\n");
739 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
740 pcc_mbox_probe, NULL, 0, NULL, 0);
742 if (IS_ERR(pcc_pdev)) {
743 pr_debug("Err creating PCC platform bundle\n");
744 return PTR_ERR(pcc_pdev);
751 * Make PCC init postcore so that users of this mailbox
752 * such as the ACPI Processor driver have it available
755 postcore_initcall(pcc_init);