diff options
Diffstat (limited to 'drivers/hwtracing/coresight/coresight-trace-id.h')
| -rw-r--r-- | drivers/hwtracing/coresight/coresight-trace-id.h | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/drivers/hwtracing/coresight/coresight-trace-id.h b/drivers/hwtracing/coresight/coresight-trace-id.h new file mode 100644 index 000000000000..3797777d367e --- /dev/null +++ b/drivers/hwtracing/coresight/coresight-trace-id.h @@ -0,0 +1,156 @@ +/* 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> + + +/* architecturally we have 128 IDs some of which are reserved */ +#define CORESIGHT_TRACE_IDS_MAX 128 + +/* 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)) + +/** + * Trace ID map. + * + * @used_ids: Bitmap to register available (bit = 0) and in use (bit = 1) IDs. + * Initialised so that the reserved IDs are permanently marked as + * in use. + * @pend_rel_ids: CPU IDs that have been released by the trace source but not + * yet marked as available, to allow re-allocation to the same + * CPU during a perf session. + */ +struct coresight_trace_id_map { + DECLARE_BITMAP(used_ids, CORESIGHT_TRACE_IDS_MAX); + DECLARE_BITMAP(pend_rel_ids, CORESIGHT_TRACE_IDS_MAX); +}; + +/* 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 */ |