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_H 8 #define _CORESIGHT_TRACE_ID_H 9 10 /* 11 * Coresight trace ID allocation API 12 * 13 * With multi cpu systems, and more additional trace sources a scalable 14 * trace ID reservation system is required. 15 * 16 * The system will allocate Ids on a demand basis, and allow them to be 17 * released when done. 18 * 19 * In order to ensure that a consistent cpu / ID matching is maintained 20 * throughout a perf cs_etm event session - a session in progress flag will be 21 * maintained for each sink, and IDs are cleared when all the perf sessions 22 * complete. This allows the same CPU to be re-allocated its prior ID when 23 * events are scheduled in and out. 24 * 25 * 26 * Trace ID maps will be created and initialised to prevent architecturally 27 * reserved IDs from being allocated. 28 * 29 * API permits multiple maps to be maintained - for large systems where 30 * 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 0 38 39 /* ID 0x70 onwards are reserved */ 40 #define CORESIGHT_TRACE_ID_RES_TOP 0x70 41 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 */ 59 int 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 operate 63 * on to be provided. 64 */ 65 int 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 */ 74 void 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 operate 78 * on to be provided. 79 */ 80 void 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 allocated 86 * for the CPU. 87 * 88 * Used in perf context where it is known that the value for the CPU will not 89 * be changing, when perf starts and event on a core and outputs the Trace ID 90 * for the CPU as a packet in the data file. IDs cannot change during a perf 91 * session. 92 * 93 * This function does not take the lock protecting the ID lists, avoiding 94 * 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 */ 100 int 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 operate 104 * on to be provided. 105 */ 106 int 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 */ 117 int 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 */ 126 void 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 a 134 * trace event. 135 * 136 * Perf sessions never free trace IDs to ensure that the ID associated with a 137 * 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 */ 140 void 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 to 146 * zero, then all Trace IDs will be released. 147 */ 148 void coresight_trace_id_perf_stop(struct coresight_trace_id_map *id_map); 149 150 #endif /* _CORESIGHT_TRACE_ID_H */ 151