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1/* SPDX-License-Identifier: GPL-2.0 */2/*3 * Copyright(C) 2022 Linaro Limited. All rights reserved.4 * Author: Mike Leach <mike.leach@linaro.org>5 */6 7#ifndef _CORESIGHT_TRACE_ID_H8#define _CORESIGHT_TRACE_ID_H9 10/*11 * Coresight trace ID allocation API12 *13 * With multi cpu systems, and more additional trace sources a scalable14 * trace ID reservation system is required.15 *16 * The system will allocate Ids on a demand basis, and allow them to be17 * released when done.18 *19 * In order to ensure that a consistent cpu / ID matching is maintained20 * throughout a perf cs_etm event session - a session in progress flag will be21 * maintained for each sink, and IDs are cleared when all the perf sessions22 * complete. This allows the same CPU to be re-allocated its prior ID when23 * events are scheduled in and out.24 *25 *26 * Trace ID maps will be created and initialised to prevent architecturally27 * reserved IDs from being allocated.28 *29 * API permits multiple maps to be maintained - for large systems where30 * different sets of cpus trace into different independent sinks.31 */32 33#include <linux/bitops.h>34#include <linux/types.h>35 36/* ID 0 is reserved */37#define CORESIGHT_TRACE_ID_RES_0 038 39/* ID 0x70 onwards are reserved */40#define CORESIGHT_TRACE_ID_RES_TOP 0x7041 42/* check an ID is in the valid range */43#define IS_VALID_CS_TRACE_ID(id) \44 ((id > CORESIGHT_TRACE_ID_RES_0) && (id < CORESIGHT_TRACE_ID_RES_TOP))45 46/**47 * Read and optionally allocate a CoreSight trace ID and associate with a CPU.48 *49 * Function will read the current trace ID for the associated CPU,50 * allocating an new ID if one is not currently allocated.51 *52 * Numeric ID values allocated use legacy allocation algorithm if possible,53 * otherwise any available ID is used.54 *55 * @cpu: The CPU index to allocate for.56 *57 * return: CoreSight trace ID or -EINVAL if allocation impossible.58 */59int coresight_trace_id_get_cpu_id(int cpu);60 61/**62 * Version of coresight_trace_id_get_cpu_id() that allows the ID map to operate63 * on to be provided.64 */65int coresight_trace_id_get_cpu_id_map(int cpu, struct coresight_trace_id_map *id_map);66 67/**68 * Release an allocated trace ID associated with the CPU.69 *70 * This will release the CoreSight trace ID associated with the CPU.71 *72 * @cpu: The CPU index to release the associated trace ID.73 */74void coresight_trace_id_put_cpu_id(int cpu);75 76/**77 * Version of coresight_trace_id_put_cpu_id() that allows the ID map to operate78 * on to be provided.79 */80void coresight_trace_id_put_cpu_id_map(int cpu, struct coresight_trace_id_map *id_map);81 82/**83 * Read the current allocated CoreSight Trace ID value for the CPU.84 *85 * Fast read of the current value that does not allocate if no ID allocated86 * for the CPU.87 *88 * Used in perf context where it is known that the value for the CPU will not89 * be changing, when perf starts and event on a core and outputs the Trace ID90 * for the CPU as a packet in the data file. IDs cannot change during a perf91 * session.92 *93 * This function does not take the lock protecting the ID lists, avoiding94 * locking dependency issues with perf locks.95 *96 * @cpu: The CPU index to read.97 *98 * return: current value, will be 0 if unallocated.99 */100int coresight_trace_id_read_cpu_id(int cpu);101 102/**103 * Version of coresight_trace_id_read_cpu_id() that allows the ID map to operate104 * on to be provided.105 */106int coresight_trace_id_read_cpu_id_map(int cpu, struct coresight_trace_id_map *id_map);107 108/**109 * Allocate a CoreSight trace ID for a system component.110 *111 * Unconditionally allocates a Trace ID, without associating the ID with a CPU.112 *113 * Used to allocate IDs for system trace sources such as STM.114 *115 * return: Trace ID or -EINVAL if allocation is impossible.116 */117int coresight_trace_id_get_system_id(void);118 119/**120 * Release an allocated system trace ID.121 *122 * Unconditionally release a trace ID allocated to a system component.123 *124 * @id: value of trace ID allocated.125 */126void coresight_trace_id_put_system_id(int id);127 128/* notifiers for perf session start and stop */129 130/**131 * Notify the Trace ID allocator that a perf session is starting.132 *133 * Increase the perf session reference count - called by perf when setting up a134 * trace event.135 *136 * Perf sessions never free trace IDs to ensure that the ID associated with a137 * CPU cannot change during their and other's concurrent sessions. Instead,138 * this refcount is used so that the last event to finish always frees all IDs.139 */140void coresight_trace_id_perf_start(struct coresight_trace_id_map *id_map);141 142/**143 * Notify the ID allocator that a perf session is stopping.144 *145 * Decrease the perf session reference count. If this causes the count to go to146 * zero, then all Trace IDs will be released.147 */148void coresight_trace_id_perf_stop(struct coresight_trace_id_map *id_map);149 150#endif /* _CORESIGHT_TRACE_ID_H */151