https://github.com/torvalds/linux
Tip revision: 4fe89d07dcc2804c8b562f6c7896a45643d34b2f authored by Linus Torvalds on 02 October 2022, 21:09:07 UTC
Linux 6.0
Linux 6.0
Tip revision: 4fe89d0
pcc.c
// 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 succeeded 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/log2.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"
/**
* struct pcc_chan_reg - PCC register bundle
*
* @vaddr: cached virtual address for this register
* @gas: pointer to the generic address structure for this register
* @preserve_mask: bitmask to preserve when writing to this register
* @set_mask: bitmask to set when writing to this register
* @status_mask: bitmask to determine and/or update the status for this register
*/
struct pcc_chan_reg {
void __iomem *vaddr;
struct acpi_generic_address *gas;
u64 preserve_mask;
u64 set_mask;
u64 status_mask;
};
/**
* struct pcc_chan_info - PCC channel specific information
*
* @chan: PCC channel information with Shared Memory Region info
* @db: PCC register bundle for the doorbell register
* @plat_irq_ack: PCC register bundle for the platform interrupt acknowledge
* register
* @cmd_complete: PCC register bundle for the command complete check register
* @cmd_update: PCC register bundle for the command complete update register
* @error: PCC register bundle for the error status register
* @plat_irq: platform interrupt
*/
struct pcc_chan_info {
struct pcc_mbox_chan chan;
struct pcc_chan_reg db;
struct pcc_chan_reg plat_irq_ack;
struct pcc_chan_reg cmd_complete;
struct pcc_chan_reg cmd_update;
struct pcc_chan_reg error;
int plat_irq;
};
#define to_pcc_chan_info(c) container_of(c, struct pcc_chan_info, chan)
static struct pcc_chan_info *chan_info;
static int pcc_chan_count;
/*
* 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 void read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
{
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;
}
}
static void write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
{
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;
}
}
static int pcc_chan_reg_read(struct pcc_chan_reg *reg, u64 *val)
{
int ret = 0;
if (!reg->gas) {
*val = 0;
return 0;
}
if (reg->vaddr)
read_register(reg->vaddr, val, reg->gas->bit_width);
else
ret = acpi_read(val, reg->gas);
return ret;
}
static int pcc_chan_reg_write(struct pcc_chan_reg *reg, u64 val)
{
int ret = 0;
if (!reg->gas)
return 0;
if (reg->vaddr)
write_register(reg->vaddr, val, reg->gas->bit_width);
else
ret = acpi_write(val, reg->gas);
return ret;
}
static int pcc_chan_reg_read_modify_write(struct pcc_chan_reg *reg)
{
int ret = 0;
u64 val;
ret = pcc_chan_reg_read(reg, &val);
if (ret)
return ret;
val &= reg->preserve_mask;
val |= reg->set_mask;
return pcc_chan_reg_write(reg, 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
* @irq: interrupt number
* @p: data/cookie passed from the caller to identify the channel
*
* Returns: IRQ_HANDLED if interrupt is handled or IRQ_NONE if not
*/
static irqreturn_t pcc_mbox_irq(int irq, void *p)
{
struct pcc_chan_info *pchan;
struct mbox_chan *chan = p;
u64 val;
int ret;
pchan = chan->con_priv;
ret = pcc_chan_reg_read(&pchan->cmd_complete, &val);
if (ret)
return IRQ_NONE;
if (val) { /* Ensure GAS exists and value is non-zero */
val &= pchan->cmd_complete.status_mask;
if (!val)
return IRQ_NONE;
}
ret = pcc_chan_reg_read(&pchan->error, &val);
if (ret)
return IRQ_NONE;
val &= pchan->error.status_mask;
if (val) {
val &= ~pchan->error.status_mask;
pcc_chan_reg_write(&pchan->error, val);
return IRQ_NONE;
}
if (pcc_chan_reg_read_modify_write(&pchan->plat_irq_ack))
return IRQ_NONE;
mbox_chan_received_data(chan, NULL);
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 PCC Mailbox Channel if successful or ERR_PTR.
*/
struct pcc_mbox_chan *
pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
{
struct pcc_chan_info *pchan;
struct mbox_chan *chan;
struct device *dev;
unsigned long flags;
if (subspace_id < 0 || subspace_id >= pcc_chan_count)
return ERR_PTR(-ENOENT);
pchan = chan_info + subspace_id;
chan = pchan->chan.mchan;
if (IS_ERR(chan) || chan->cl) {
pr_err("Channel not found for idx: %d\n", subspace_id);
return ERR_PTR(-EBUSY);
}
dev = chan->mbox->dev;
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 (pchan->plat_irq > 0) {
int rc;
rc = devm_request_irq(dev, pchan->plat_irq, pcc_mbox_irq, 0,
MBOX_IRQ_NAME, chan);
if (unlikely(rc)) {
dev_err(dev, "failed to register PCC interrupt %d\n",
pchan->plat_irq);
pcc_mbox_free_channel(&pchan->chan);
return ERR_PTR(rc);
}
}
return &pchan->chan;
}
EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
/**
* pcc_mbox_free_channel - Clients call this to free their Channel.
*
* @pchan: Pointer to the PCC mailbox channel as returned by
* pcc_mbox_request_channel()
*/
void pcc_mbox_free_channel(struct pcc_mbox_chan *pchan)
{
struct pcc_chan_info *pchan_info = to_pcc_chan_info(pchan);
struct mbox_chan *chan = pchan->mchan;
unsigned long flags;
if (!chan || !chan->cl)
return;
if (pchan_info->plat_irq > 0)
devm_free_irq(chan->mbox->dev, pchan_info->plat_irq, 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)
{
int ret;
struct pcc_chan_info *pchan = chan->con_priv;
ret = pcc_chan_reg_read_modify_write(&pchan->cmd_update);
if (ret)
return ret;
return pcc_chan_reg_read_modify_write(&pchan->db);
}
static const struct mbox_chan_ops pcc_chan_ops = {
.send_data = pcc_send_data,
};
/**
* parse_pcc_subspace - 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;
}
static int
pcc_chan_reg_init(struct pcc_chan_reg *reg, struct acpi_generic_address *gas,
u64 preserve_mask, u64 set_mask, u64 status_mask, char *name)
{
if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
if (!(gas->bit_width >= 8 && gas->bit_width <= 64 &&
is_power_of_2(gas->bit_width))) {
pr_err("Error: Cannot access register of %u bit width",
gas->bit_width);
return -EFAULT;
}
reg->vaddr = acpi_os_ioremap(gas->address, gas->bit_width / 8);
if (!reg->vaddr) {
pr_err("Failed to ioremap PCC %s register\n", name);
return -ENOMEM;
}
}
reg->gas = gas;
reg->preserve_mask = preserve_mask;
reg->set_mask = set_mask;
reg->status_mask = status_mask;
return 0;
}
/**
* pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
*
* @pchan: Pointer to the PCC channel info structure.
* @pcct_entry: Pointer to the ACPI subtable header.
*
* Return: 0 for Success, else errno.
*
* There should be one entry per PCC channel. This gets called for each
* entry in the PCC table. This uses PCCY Type1 structure for all applicable
* types(Type 1-4) to fetch irq
*/
static int pcc_parse_subspace_irq(struct pcc_chan_info *pchan,
struct acpi_subtable_header *pcct_entry)
{
int ret = 0;
struct acpi_pcct_hw_reduced *pcct_ss;
if (pcct_entry->type < ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
pcct_entry->type > ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
return 0;
pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
pchan->plat_irq = pcc_map_interrupt(pcct_ss->platform_interrupt,
(u32)pcct_ss->flags);
if (pchan->plat_irq <= 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;
ret = pcc_chan_reg_init(&pchan->plat_irq_ack,
&pcct2_ss->platform_ack_register,
pcct2_ss->ack_preserve_mask,
pcct2_ss->ack_write_mask, 0,
"PLAT IRQ ACK");
} else if (pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE ||
pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE) {
struct acpi_pcct_ext_pcc_master *pcct_ext = (void *)pcct_ss;
ret = pcc_chan_reg_init(&pchan->plat_irq_ack,
&pcct_ext->platform_ack_register,
pcct_ext->ack_preserve_mask,
pcct_ext->ack_set_mask, 0,
"PLAT IRQ ACK");
}
return ret;
}
/**
* pcc_parse_subspace_db_reg - Parse the PCC doorbell register
*
* @pchan: Pointer to the PCC channel info structure.
* @pcct_entry: Pointer to the ACPI subtable header.
*
* Return: 0 for Success, else errno.
*/
static int pcc_parse_subspace_db_reg(struct pcc_chan_info *pchan,
struct acpi_subtable_header *pcct_entry)
{
int ret = 0;
if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
struct acpi_pcct_subspace *pcct_ss;
pcct_ss = (struct acpi_pcct_subspace *)pcct_entry;
ret = pcc_chan_reg_init(&pchan->db,
&pcct_ss->doorbell_register,
pcct_ss->preserve_mask,
pcct_ss->write_mask, 0, "Doorbell");
} else {
struct acpi_pcct_ext_pcc_master *pcct_ext;
pcct_ext = (struct acpi_pcct_ext_pcc_master *)pcct_entry;
ret = pcc_chan_reg_init(&pchan->db,
&pcct_ext->doorbell_register,
pcct_ext->preserve_mask,
pcct_ext->write_mask, 0, "Doorbell");
if (ret)
return ret;
ret = pcc_chan_reg_init(&pchan->cmd_complete,
&pcct_ext->cmd_complete_register,
0, 0, pcct_ext->cmd_complete_mask,
"Command Complete Check");
if (ret)
return ret;
ret = pcc_chan_reg_init(&pchan->cmd_update,
&pcct_ext->cmd_update_register,
pcct_ext->cmd_update_preserve_mask,
pcct_ext->cmd_update_set_mask, 0,
"Command Complete Update");
if (ret)
return ret;
ret = pcc_chan_reg_init(&pchan->error,
&pcct_ext->error_status_register,
0, 0, pcct_ext->error_status_mask,
"Error Status");
}
return ret;
}
/**
* pcc_parse_subspace_shmem - Parse the PCC Shared Memory Region information
*
* @pchan: Pointer to the PCC channel info structure.
* @pcct_entry: Pointer to the ACPI subtable header.
*
*/
static void pcc_parse_subspace_shmem(struct pcc_chan_info *pchan,
struct acpi_subtable_header *pcct_entry)
{
if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
struct acpi_pcct_subspace *pcct_ss =
(struct acpi_pcct_subspace *)pcct_entry;
pchan->chan.shmem_base_addr = pcct_ss->base_address;
pchan->chan.shmem_size = pcct_ss->length;
pchan->chan.latency = pcct_ss->latency;
pchan->chan.max_access_rate = pcct_ss->max_access_rate;
pchan->chan.min_turnaround_time = pcct_ss->min_turnaround_time;
} else {
struct acpi_pcct_ext_pcc_master *pcct_ext =
(struct acpi_pcct_ext_pcc_master *)pcct_entry;
pchan->chan.shmem_base_addr = pcct_ext->base_address;
pchan->chan.shmem_size = pcct_ext->length;
pchan->chan.latency = pcct_ext->latency;
pchan->chan.max_access_rate = pcct_ext->max_access_rate;
pchan->chan.min_turnaround_time = pcct_ext->min_turnaround_time;
}
}
/**
* acpi_pcc_probe - Parse the ACPI tree for the PCCT.
*
* Return: 0 for Success, else errno.
*/
static int __init acpi_pcc_probe(void)
{
int count, i, rc = 0;
acpi_status status;
struct acpi_table_header *pcct_tbl;
struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
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;
} else {
pcc_chan_count = count;
}
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)
{
struct device *dev = &pdev->dev;
struct mbox_controller *pcc_mbox_ctrl;
struct mbox_chan *pcc_mbox_channels;
struct acpi_table_header *pcct_tbl;
struct acpi_subtable_header *pcct_entry;
struct acpi_table_pcct *acpi_pcct_tbl;
acpi_status status = AE_OK;
int i, rc, count = pcc_chan_count;
/* Search for PCCT */
status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
if (ACPI_FAILURE(status) || !pcct_tbl)
return -ENODEV;
pcc_mbox_channels = devm_kcalloc(dev, count, sizeof(*pcc_mbox_channels),
GFP_KERNEL);
if (!pcc_mbox_channels) {
rc = -ENOMEM;
goto err;
}
chan_info = devm_kcalloc(dev, count, sizeof(*chan_info), GFP_KERNEL);
if (!chan_info) {
rc = -ENOMEM;
goto err;
}
pcc_mbox_ctrl = devm_kzalloc(dev, sizeof(*pcc_mbox_ctrl), GFP_KERNEL);
if (!pcc_mbox_ctrl) {
rc = -ENOMEM;
goto err;
}
/* 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 pcc_chan_info *pchan = chan_info + i;
pcc_mbox_channels[i].con_priv = pchan;
pchan->chan.mchan = &pcc_mbox_channels[i];
if (pcct_entry->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE &&
!pcc_mbox_ctrl->txdone_irq) {
pr_err("Plaform Interrupt flag must be set to 1");
rc = -EINVAL;
goto err;
}
if (pcc_mbox_ctrl->txdone_irq) {
rc = pcc_parse_subspace_irq(pchan, pcct_entry);
if (rc < 0)
goto err;
}
rc = pcc_parse_subspace_db_reg(pchan, pcct_entry);
if (rc < 0)
goto err;
pcc_parse_subspace_shmem(pchan, pcct_entry);
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);
pcc_mbox_ctrl->chans = pcc_mbox_channels;
pcc_mbox_ctrl->ops = &pcc_chan_ops;
pcc_mbox_ctrl->dev = dev;
pr_info("Registering PCC driver as Mailbox controller\n");
rc = mbox_controller_register(pcc_mbox_ctrl);
if (rc)
pr_err("Err registering PCC as Mailbox controller: %d\n", rc);
else
return 0;
err:
acpi_put_table(pcct_tbl);
return rc;
}
static struct platform_driver pcc_mbox_driver = {
.probe = pcc_mbox_probe,
.driver = {
.name = "PCCT",
},
};
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);