// SPDX-License-Identifier: GPL-2.0-only
/*
* CPPC (Collaborative Processor Performance Control) methods used by CPUfreq drivers.
*
* (C) Copyright 2014, 2015 Linaro Ltd.
* Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
*
* CPPC describes a few methods for controlling CPU performance using
* information from a per CPU table called CPC. This table is described in
* the ACPI v5.0+ specification. The table consists of a list of
* registers which may be memory mapped or hardware registers and also may
* include some static integer values.
*
* CPU performance is on an abstract continuous scale as against a discretized
* P-state scale which is tied to CPU frequency only. In brief, the basic
* operation involves:
*
* - OS makes a CPU performance request. (Can provide min and max bounds)
*
* - Platform (such as BMC) is free to optimize request within requested bounds
* depending on power/thermal budgets etc.
*
* - Platform conveys its decision back to OS
*
* The communication between OS and platform occurs through another medium
* called (PCC) Platform Communication Channel. This is a generic mailbox like
* mechanism which includes doorbell semantics to indicate register updates.
* See drivers/mailbox/pcc.c for details on PCC.
*
* Finer details about the PCC and CPPC spec are available in the ACPI v5.1 and
* above specifications.
*/
#define pr_fmt(fmt) "ACPI CPPC: " fmt
#include <linux/delay.h>
#include <linux/iopoll.h>
#include <linux/ktime.h>
#include <linux/rwsem.h>
#include <linux/wait.h>
#include <linux/topology.h>
#include <acpi/cppc_acpi.h>
struct cppc_pcc_data {
struct pcc_mbox_chan *pcc_channel;
void __iomem *pcc_comm_addr;
bool pcc_channel_acquired;
unsigned int deadline_us;
unsigned int pcc_mpar, pcc_mrtt, pcc_nominal;
bool pending_pcc_write_cmd; /* Any pending/batched PCC write cmds? */
bool platform_owns_pcc; /* Ownership of PCC subspace */
unsigned int pcc_write_cnt; /* Running count of PCC write commands */
/*
