blob: ef9ecd1f595880f197140103759b1c2a2a3874bd [file] [log] [blame]
// 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);