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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright(C) 2022 Linaro Limited. All rights reserved.
* Author: Mike Leach <mike.leach@linaro.org>
*/
#ifndef _CORESIGHT_TRACE_ID_H
#define _CORESIGHT_TRACE_ID_H
/*
* Coresight trace ID allocation API
*
* With multi cpu systems, and more additional trace sources a scalable
* trace ID reservation system is required.
*
* The system will allocate Ids on a demand basis, and allow them to be
* released when done.
*
* In order to ensure that a consistent cpu / ID matching is maintained
* throughout a perf cs_etm event session - a session in progress flag will
* be maintained, and released IDs not cleared until the perf session is
* complete. This allows the same CPU to be re-allocated its prior ID.
*
*
* Trace ID maps will be created and initialised to prevent architecturally
* reserved IDs from being allocated.
*
* API permits multiple maps to be maintained - for large systems where
* different sets of cpus trace into different independent sinks.
*/
#include <linux/bitops.h>
#include <linux/types.h>
/* ID 0 is reserved */
#define CORESIGHT_TRACE_ID_RES_0 0
/* ID 0x70 onwards are reserved */
#define CORESIGHT_TRACE_ID_RES_TOP 0x70
/* check an ID is in the valid range */
#define IS_VALID_CS_TRACE_ID(id) \
((id > CORESIGHT_TRACE_ID_RES_0) && (id < CORESIGHT_TRACE_ID_RES_TOP))
/* Allocate and release IDs for a single default trace ID map */
/**
* Read and optionally allocate a CoreSight trace ID and associate with a CPU.
*
* Function will read the current trace ID for the associated CPU,
* allocating an new ID if one is not currently allocated.
*
* Numeric ID values allocated use legacy allocation algorithm if possible,
* otherwise any available ID is used.
*
* @cpu: The CPU index to allocate for.
*
* return: CoreSight trace ID or -EINVAL if allocation impossible.
*/
int coresight_trace_id_get_cpu_id(int cpu);
/**
* Release an allocated trace ID associated with the CPU.
*
* This will release the CoreSight trace ID associated with the CPU,
* unless a perf session is in operation.
*
* If a perf session is in operation then the ID will be marked as pending
* release.
*
* @cpu: The CPU index to release the associated trace ID.
*/
void coresight_trace_id_put_cpu_id(int cpu);
/**
* Read the current allocated CoreSight Trace ID value for the CPU.
*
* Fast read of the current value that does not allocate if no ID allocated
* for the CPU.
*
* Used in perf context where it is known that the value for the CPU will not
* be changing, when perf starts and event on a core and outputs the Trace ID
* for the CPU as a packet in the data file. IDs cannot change during a perf
* session.
*
* This function does not take the lock protecting the ID lists, avoiding
* locking dependency issues with perf locks.
*
* @cpu: The CPU index to read.
*
* return: current value, will be 0 if unallocated.
*/
int coresight_trace_id_read_cpu_id(int cpu);
/**
* Allocate a CoreSight trace ID for a system component.
*
* Unconditionally allocates a Trace ID, without associating the ID with a CPU.
*
* Used to allocate IDs for system trace sources such as STM.
*
* return: Trace ID or -EINVAL if allocation is impossible.
*/
int coresight_trace_id_get_system_id(void);
/**
* Release an allocated system trace ID.
*
* Unconditionally release a trace ID allocated to a system component.
*
* @id: value of trace ID allocated.
*/
void coresight_trace_id_put_system_id(int id);
/* notifiers for perf session start and stop */
/**
* Notify the Trace ID allocator that a perf session is starting.
*
* Increase the perf session reference count - called by perf when setting up
* a trace event.
*
* This reference count is used by the ID allocator to ensure that trace IDs
* associated with a CPU cannot change or be released during a perf session.
*/
void coresight_trace_id_perf_start(void);
/**
* Notify the ID allocator that a perf session is stopping.
*
* Decrease the perf session reference count.
* if this causes the count to go to zero, then all Trace IDs marked as pending
* release, will be released.
*/
void coresight_trace_id_perf_stop(void);
#endif /* _CORESIGHT_TRACE_ID_H */
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