linux/drivers/acpi/acpi_pcc.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Author: Sudeep Holla <[email protected]>
 * Copyright 2021 Arm Limited
 *
 * The PCC Address Space also referred as PCC Operation Region pertains to the
 * region of PCC subspace that succeeds the PCC signature. The PCC Operation
 * Region works in conjunction with the PCC Table(Platform Communications
 * Channel Table). PCC subspaces that are marked for use as PCC Operation
 * Regions must not be used as PCC subspaces for the standard ACPI features
 * such as CPPC, RASF, PDTT and MPST. These standard features must always use
 * the PCC Table instead.
 *
 * This driver sets up the PCC Address Space and installs an handler to enable
 * handling of PCC OpRegion in the firmware.
 *
 */
#include <linux/kernel.h>
#include <linux/acpi.h>
#include <linux/completion.h>
#include <linux/idr.h>
#include <linux/io.h>

#include <acpi/pcc.h>

/*
 * Arbitrary retries in case the remote processor is slow to respond
 * to PCC commands
 */
#define PCC_CMD_WAIT_RETRIES_NUM …

struct pcc_data { … };

static struct acpi_pcc_info pcc_ctx;

static void pcc_rx_callback(struct mbox_client *cl, void *m)
{ … }

static acpi_status
acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
			     void *handler_context,  void **region_context)
{ … }

static acpi_status
acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr,
			       u32 bits, acpi_integer *value,
			       void *handler_context, void *region_context)
{ … }

void __init acpi_init_pcc(void)
{ … }