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 if (val) { /* Ensure GAS exists and value is non-zero */
245 val &= pchan->cmd_complete.status_mask;
250 ret = pcc_chan_reg_read(&pchan->error, &val);
253 val &= pchan->error.status_mask;
255 val &= ~pchan->error.status_mask;
256 pcc_chan_reg_write(&pchan->error, val);
260 if (pcc_chan_reg_read_modify_write(&pchan->plat_irq_ack))
263 mbox_chan_received_data(chan, NULL);
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
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.
278 * Return: Pointer to the PCC Mailbox Channel if successful or ERR_PTR.
280 struct pcc_mbox_chan *
281 pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
283 struct pcc_chan_info *pchan;
284 struct mbox_chan *chan;
288 if (subspace_id < 0 || subspace_id >= pcc_chan_count)
289 return ERR_PTR(-ENOENT);
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);
297 dev = chan->mbox->dev;
299 spin_lock_irqsave(&chan->lock, flags);
302 chan->active_req = NULL;
304 init_completion(&chan->tx_complete);
306 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
307 chan->txdone_method = TXDONE_BY_ACK;
309 spin_unlock_irqrestore(&chan->lock, flags);
311 if (pchan->plat_irq > 0) {
314 rc = devm_request_irq(dev, pchan->plat_irq, pcc_mbox_irq, 0,
315 MBOX_IRQ_NAME, chan);
317 dev_err(dev, "failed to register PCC interrupt %d\n",
319 pcc_mbox_free_channel(&pchan->chan);
326 EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
329 * pcc_mbox_free_channel - Clients call this to free their Channel.
331 * @pchan: Pointer to the PCC mailbox channel as returned by
332 * pcc_mbox_request_channel()
334 void pcc_mbox_free_channel(struct pcc_mbox_chan *pchan)
336 struct pcc_chan_info *pchan_info = to_pcc_chan_info(pchan);
337 struct mbox_chan *chan = pchan->mchan;
340 if (!chan || !chan->cl)
343 if (pchan_info->plat_irq > 0)
344 devm_free_irq(chan->mbox->dev, pchan_info->plat_irq, chan);
346 spin_lock_irqsave(&chan->lock, flags);
348 chan->active_req = NULL;
349 if (chan->txdone_method == TXDONE_BY_ACK)
350 chan->txdone_method = TXDONE_BY_POLL;
352 spin_unlock_irqrestore(&chan->lock, flags);
354 EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
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.
366 * Return: Err if something failed else 0 for success.
368 static int pcc_send_data(struct mbox_chan *chan, void *data)
371 struct pcc_chan_info *pchan = chan->con_priv;
373 ret = pcc_chan_reg_read_modify_write(&pchan->cmd_update);
377 return pcc_chan_reg_read_modify_write(&pchan->db);
380 static const struct mbox_chan_ops pcc_chan_ops = {
381 .send_data = pcc_send_data,
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.
389 * Return: If we find a PCC subspace entry of a valid type, return 0.
390 * Otherwise, return -EINVAL.
392 * This gets called for each entry in the PCC table.
394 static int parse_pcc_subspace(union acpi_subtable_headers *header,
395 const unsigned long end)
397 struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;
399 if (ss->header.type < ACPI_PCCT_TYPE_RESERVED)
406 pcc_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)
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",
417 reg->vaddr = acpi_os_ioremap(gas->address, gas->bit_width / 8);
419 pr_err("Failed to ioremap PCC %s register\n", name);
424 reg->preserve_mask = preserve_mask;
425 reg->set_mask = set_mask;
426 reg->status_mask = status_mask;
431 * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
433 * @pchan: Pointer to the PCC channel info structure.
434 * @pcct_entry: Pointer to the ACPI subtable header.
436 * Return: 0 for Success, else errno.
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
442 static int pcc_parse_subspace_irq(struct pcc_chan_info *pchan,
443 struct acpi_subtable_header *pcct_entry)
446 struct acpi_pcct_hw_reduced *pcct_ss;
448 if (pcct_entry->type < ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
449 pcct_entry->type > ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
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);
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;
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,
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;
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,
485 * pcc_parse_subspace_db_reg - Parse the PCC doorbell register
487 * @pchan: Pointer to the PCC channel info structure.
488 * @pcct_entry: Pointer to the ACPI subtable header.
490 * Return: 0 for Success, else errno.
492 static int pcc_parse_subspace_db_reg(struct pcc_chan_info *pchan,
493 struct acpi_subtable_header *pcct_entry)
497 if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
498 struct acpi_pcct_subspace *pcct_ss;
500 pcct_ss = (struct acpi_pcct_subspace *)pcct_entry;
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");
508 struct acpi_pcct_ext_pcc_master *pcct_ext;
510 pcct_ext = (struct acpi_pcct_ext_pcc_master *)pcct_entry;
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");
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");
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");
534 ret = pcc_chan_reg_init(&pchan->error,
535 &pcct_ext->error_status_register,
536 0, 0, pcct_ext->error_status_mask,
543 * pcc_parse_subspace_shmem - Parse the PCC Shared Memory Region information
545 * @pchan: Pointer to the PCC channel info structure.
546 * @pcct_entry: Pointer to the ACPI subtable header.
549 static void pcc_parse_subspace_shmem(struct pcc_chan_info *pchan,
550 struct acpi_subtable_header *pcct_entry)
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;
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;
562 struct acpi_pcct_ext_pcc_master *pcct_ext =
563 (struct acpi_pcct_ext_pcc_master *)pcct_entry;
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;
574 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
576 * Return: 0 for Success, else errno.
578 static int __init acpi_pcc_probe(void)
580 int count, i, rc = 0;
582 struct acpi_table_header *pcct_tbl;
583 struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
585 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
586 if (ACPI_FAILURE(status) || !pcct_tbl)
589 /* Set up the subtable handlers */
590 for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
591 i < ACPI_PCCT_TYPE_RESERVED; i++) {
594 proc[i].handler = parse_pcc_subspace;
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) {
602 pr_warn("Error parsing PCC subspaces from PCCT\n");
604 pr_warn("Invalid PCCT: %d PCC subspaces\n", count);
608 pcc_chan_count = count;
611 acpi_put_table(pcct_tbl);
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.
622 * @pdev: Pointer to platform device returned when a match
625 * Return: 0 for Success, else errno.
627 static int pcc_mbox_probe(struct platform_device *pdev)
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;
638 /* Search for PCCT */
639 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
641 if (ACPI_FAILURE(status) || !pcct_tbl)
644 pcc_mbox_channels = devm_kcalloc(dev, count, sizeof(*pcc_mbox_channels),
646 if (!pcc_mbox_channels) {
651 chan_info = devm_kcalloc(dev, count, sizeof(*chan_info), GFP_KERNEL);
657 pcc_mbox_ctrl = devm_kzalloc(dev, sizeof(*pcc_mbox_ctrl), GFP_KERNEL);
658 if (!pcc_mbox_ctrl) {
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));
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;
671 for (i = 0; i < count; i++) {
672 struct pcc_chan_info *pchan = chan_info + i;
674 pcc_mbox_channels[i].con_priv = pchan;
675 pchan->chan.mchan = &pcc_mbox_channels[i];
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");
684 if (pcc_mbox_ctrl->txdone_irq) {
685 rc = pcc_parse_subspace_irq(pchan, pcct_entry);
689 rc = pcc_parse_subspace_db_reg(pchan, pcct_entry);
693 pcc_parse_subspace_shmem(pchan, pcct_entry);
695 pcct_entry = (struct acpi_subtable_header *)
696 ((unsigned long) pcct_entry + pcct_entry->length);
699 pcc_mbox_ctrl->num_chans = count;
701 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl->num_chans);
703 pcc_mbox_ctrl->chans = pcc_mbox_channels;
704 pcc_mbox_ctrl->ops = &pcc_chan_ops;
705 pcc_mbox_ctrl->dev = dev;
707 pr_info("Registering PCC driver as Mailbox controller\n");
708 rc = mbox_controller_register(pcc_mbox_ctrl);
710 pr_err("Err registering PCC as Mailbox controller: %d\n", rc);
714 acpi_put_table(pcct_tbl);
718 static struct platform_driver pcc_mbox_driver = {
719 .probe = pcc_mbox_probe,
725 static int __init pcc_init(void)
728 struct platform_device *pcc_pdev;
733 /* Check if PCC support is available. */
734 ret = acpi_pcc_probe();
737 pr_debug("ACPI PCC probe failed.\n");
741 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
742 pcc_mbox_probe, NULL, 0, NULL, 0);
744 if (IS_ERR(pcc_pdev)) {
745 pr_debug("Err creating PCC platform bundle\n");
747 return PTR_ERR(pcc_pdev);
754 * Make PCC init postcore so that users of this mailbox
755 * such as the ACPI Processor driver have it available
758 postcore_initcall(pcc_init);