/*
* Copyright (C) 2014 Linaro Ltd.
* Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* 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. See pcc_send_data()
* and pcc_tx_done() for basic mode of operation.
*
* 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/list.h>
#include <linux/platform_device.h>
#include <linux/mailbox_controller.h>
#include <linux/mailbox_client.h>
#include "mailbox.h"
#define MAX_PCC_SUBSPACES 256
#define PCCS_SS_SIG_MAGIC 0x50434300
#define PCC_CMD_COMPLETE 0x1
static struct mbox_chan *pcc_mbox_channels;
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)
{
struct mbox_chan *pcc_chan;
if (id < 0 || id > pcc_mbox_ctrl.num_chans)
return ERR_PTR(-ENOENT);
pcc_chan = (struct mbox_chan *)
(unsigned long) pcc_mbox_channels +
(id * sizeof(*pcc_chan));
return pcc_chan;
}
/**
* get_subspace_id - Given a Mailbox channel, find out the
* PCC subspace id.
* @chan: Pointer to Mailbox Channel from which we want
* the index.
* Return: Errno if not found, else positive index number.
*/
static int get_subspace_id(struct mbox_chan *chan)
{
unsigned int id = chan - pcc_mbox_channels;
if (id < 0 || id > pcc_mbox_ctrl.num_chans)
return -ENOENT;
return id;
}
/**
* 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 (!chan || chan->cl) {
dev_err(dev, "%s: PCC mailbox not free\n", __func__);
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);
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)
{
unsigned long flags;
if (!chan || !chan->cl)
return;
spin_lock_irqsave(&chan->lock, flags);
chan->cl = NULL;
chan->active_req = NULL;
if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
chan->txdone_method = TXDONE_BY_POLL;
spin_unlock_irqrestore(&chan->lock, flags);
}
EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
/**
* pcc_tx_done - Callback from Mailbox controller code to
* check if PCC message transmission completed.
* @chan: Pointer to Mailbox channel on which previous
* transmission occurred.
*
* Return: TRUE if succeeded.
*/
static bool pcc_tx_done(struct mbox_chan *chan)
{
struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
struct acpi_pcct_shared_memory *generic_comm_base =
(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
u16 cmd_delay = pcct_ss->latency;
unsigned int retries = 0;
/* Try a few times while waiting for platform to consume */
while (!(readw_relaxed(&generic_comm_base->status)
& PCC_CMD_COMPLETE)) {
if (retries++ < 5)
udelay(cmd_delay);
else {
/*
* If the remote is dead, this will cause the Mbox
* controller to timeout after mbox client.tx_tout
* msecs.
*/
pr_err("PCC platform did not respond.\n");
return false;
}
}
return true;
}
/**
* pcc_send_data - Called from Mailbox Controller code to finally
* transmit data over channel.
* @chan: Pointer to Mailbox channel over which to send data.
* @data: Actual data to be written over channel.
*
* 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_pcct_shared_memory *generic_comm_base =
(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
struct acpi_generic_address doorbell;
u64 doorbell_preserve;
u64 doorbell_val;
u64 doorbell_write;
u16 cmd = *(u16 *) data;
u16 ss_idx = -1;
ss_idx = get_subspace_id(chan);
if (ss_idx < 0) {
pr_err("Invalid Subspace ID from PCC client\n");
return -EINVAL;
}
doorbell = pcct_ss->doorbell_register;
doorbell_preserve = pcct_ss->preserve_mask;
doorbell_write = pcct_ss->write_mask;
/* Write to the shared comm region. */
writew(cmd, &generic_comm_base->command);
/* Write Subspace MAGIC value so platform can identify destination. */
writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
/* Flip CMD COMPLETE bit */
writew(0, &generic_comm_base->status);
/* Sync notification from OSPM to Platform. */
acpi_read(&doorbell_val, &doorbell);
acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
&doorbell);
return 0;
}
static struct mbox_chan_ops pcc_chan_ops = {
.send_data = pcc_send_data,
.last_tx_done = pcc_tx_done,
};
/**
* parse_pcc_subspace - Parse the PCC table and verify PCC subspace
* entries. There should be one entry per PCC client.
* @header: Pointer to the ACPI subtable header under the PCCT.
* @end: End of subtable entry.
*
* Return: 0 for Success, else errno.
*
* This gets called for each entry in the PCC table.
*/
static int parse_pcc_subspace(struct acpi_subtable_header *header,
const unsigned long end)
{
struct acpi_pcct_hw_reduced *pcct_ss;
if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
pcct_ss = (struct acpi_pcct_hw_reduced *) header;
if (pcct_ss->header.type !=
ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) {
pr_err("Incorrect PCC Subspace type detected\n");
return -EINVAL;
}
}
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)
{
acpi_size pcct_tbl_header_size;
struct acpi_table_header *pcct_tbl;
struct acpi_subtable_header *pcct_entry;
int count, i;
acpi_status status = AE_OK;
/* Search for PCCT */
status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,
&pcct_tbl,
&pcct_tbl_header_size);
if (ACPI_FAILURE(status) || !pcct_tbl) {
pr_warn("PCCT header not found.\n");
return -ENODEV;
}
count = acpi_table_parse_entries(ACPI_SIG_PCCT,
sizeof(struct acpi_table_pcct),
ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
parse_pcc_subspace, MAX_PCC_SUBSPACES);
if (count <= 0) {
pr_err("Error parsing PCC subspaces from PCCT\n");
return -EINVAL;
}
pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
count, GFP_KERNEL);
if (!pcc_mbox_channels) {
pr_err("Could not allocate space for PCC mbox channels\n");
return -ENOMEM;
}
/* Point to the first PCC subspace entry */
pcct_entry = (struct acpi_subtable_header *) (
(unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
for (i = 0; i < count; i++) {
pcc_mbox_channels[i].con_priv = 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);
return 0;
}
/**
* 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.txdone_poll = true;
pcc_mbox_ctrl.txpoll_period = 10;
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;
}
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;
}
device_initcall(pcc_init);
