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#include <linux/coresight-pmu.h>
  7#include <linux/cpumask.h>
  8#include <linux/kernel.h>
  9#include <linux/spinlock.h>
 10#include <linux/types.h>
 11
 12#include "coresight-trace-id.h"
 13
 14/* Default trace ID map. Used on systems that don't require per sink mappings */
 15static struct coresight_trace_id_map id_map_default;
 16
 17/* maintain a record of the mapping of IDs and pending releases per cpu */
 18static DEFINE_PER_CPU(atomic_t, cpu_id) = ATOMIC_INIT(0);
 19static cpumask_t cpu_id_release_pending;
 20
 21/* perf session active counter */
 22static atomic_t perf_cs_etm_session_active = ATOMIC_INIT(0);
 23
 24/* lock to protect id_map and cpu data  */
 25static DEFINE_SPINLOCK(id_map_lock);
 26
 27/* #define TRACE_ID_DEBUG 1 */
 28#if defined(TRACE_ID_DEBUG) || defined(CONFIG_COMPILE_TEST)
 29
 30static void coresight_trace_id_dump_table(struct coresight_trace_id_map *id_map,
 31					  const char *func_name)
 32{
 33	pr_debug("%s id_map::\n", func_name);
 34	pr_debug("Used = %*pb\n", CORESIGHT_TRACE_IDS_MAX, id_map->used_ids);
 35	pr_debug("Pend = %*pb\n", CORESIGHT_TRACE_IDS_MAX, id_map->pend_rel_ids);
 36}
 37#define DUMP_ID_MAP(map)   coresight_trace_id_dump_table(map, __func__)
 38#define DUMP_ID_CPU(cpu, id) pr_debug("%s called;  cpu=%d, id=%d\n", __func__, cpu, id)
 39#define DUMP_ID(id)   pr_debug("%s called; id=%d\n", __func__, id)
 40#define PERF_SESSION(n) pr_debug("%s perf count %d\n", __func__, n)
 41#else
 42#define DUMP_ID_MAP(map)
 43#define DUMP_ID(id)
 44#define DUMP_ID_CPU(cpu, id)
 45#define PERF_SESSION(n)
 46#endif
 47
 48/* unlocked read of current trace ID value for given CPU */
 49static int _coresight_trace_id_read_cpu_id(int cpu)
 50{
 51	return atomic_read(&per_cpu(cpu_id, cpu));
 52}
 53
 54/* look for next available odd ID, return 0 if none found */
 55static int coresight_trace_id_find_odd_id(struct coresight_trace_id_map *id_map)
 56{
 57	int found_id = 0, bit = 1, next_id;
 58
 59	while ((bit < CORESIGHT_TRACE_ID_RES_TOP) && !found_id) {
 60		/*
 61		 * bitmap length of CORESIGHT_TRACE_ID_RES_TOP,
 62		 * search from offset `bit`.
 63		 */
 64		next_id = find_next_zero_bit(id_map->used_ids,
 65					     CORESIGHT_TRACE_ID_RES_TOP, bit);
 66		if ((next_id < CORESIGHT_TRACE_ID_RES_TOP) && (next_id & 0x1))
 67			found_id = next_id;
 68		else
 69			bit = next_id + 1;
 70	}
 71	return found_id;
 72}
 73
 74/*
 75 * Allocate new ID and set in use
 76 *
 77 * if @preferred_id is a valid id then try to use that value if available.
 78 * if @preferred_id is not valid and @prefer_odd_id is true, try for odd id.
 79 *
 80 * Otherwise allocate next available ID.
 81 */
 82static int coresight_trace_id_alloc_new_id(struct coresight_trace_id_map *id_map,
 83					   int preferred_id, bool prefer_odd_id)
 84{
 85	int id = 0;
 86
 87	/* for backwards compatibility, cpu IDs may use preferred value */
 88	if (IS_VALID_CS_TRACE_ID(preferred_id) &&
 89	    !test_bit(preferred_id, id_map->used_ids)) {
 90		id = preferred_id;
 91		goto trace_id_allocated;
 92	} else if (prefer_odd_id) {
 93	/* may use odd ids to avoid preferred legacy cpu IDs */
 94		id = coresight_trace_id_find_odd_id(id_map);
 95		if (id)
 96			goto trace_id_allocated;
 97	}
 98
 99	/*
100	 * skip reserved bit 0, look at bitmap length of
101	 * CORESIGHT_TRACE_ID_RES_TOP from offset of bit 1.
102	 */
103	id = find_next_zero_bit(id_map->used_ids, CORESIGHT_TRACE_ID_RES_TOP, 1);
104	if (id >= CORESIGHT_TRACE_ID_RES_TOP)
105		return -EINVAL;
106
107	/* mark as used */
108trace_id_allocated:
109	set_bit(id, id_map->used_ids);
110	return id;
111}
112
113static void coresight_trace_id_free(int id, struct coresight_trace_id_map *id_map)
114{
115	if (WARN(!IS_VALID_CS_TRACE_ID(id), "Invalid Trace ID %d\n", id))
116		return;
117	if (WARN(!test_bit(id, id_map->used_ids), "Freeing unused ID %d\n", id))
118		return;
119	clear_bit(id, id_map->used_ids);
120}
121
122static void coresight_trace_id_set_pend_rel(int id, struct coresight_trace_id_map *id_map)
123{
124	if (WARN(!IS_VALID_CS_TRACE_ID(id), "Invalid Trace ID %d\n", id))
125		return;
126	set_bit(id, id_map->pend_rel_ids);
127}
128
129/*
130 * release all pending IDs for all current maps & clear CPU associations
131 *
132 * This currently operates on the default id map, but may be extended to
133 * operate on all registered id maps if per sink id maps are used.
134 */
135static void coresight_trace_id_release_all_pending(void)
136{
137	struct coresight_trace_id_map *id_map = &id_map_default;
138	unsigned long flags;
139	int cpu, bit;
140
141	spin_lock_irqsave(&id_map_lock, flags);
142	for_each_set_bit(bit, id_map->pend_rel_ids, CORESIGHT_TRACE_ID_RES_TOP) {
143		clear_bit(bit, id_map->used_ids);
144		clear_bit(bit, id_map->pend_rel_ids);
145	}
146	for_each_cpu(cpu, &cpu_id_release_pending) {
147		atomic_set(&per_cpu(cpu_id, cpu), 0);
148		cpumask_clear_cpu(cpu, &cpu_id_release_pending);
149	}
150	spin_unlock_irqrestore(&id_map_lock, flags);
151	DUMP_ID_MAP(id_map);
152}
153
154static int coresight_trace_id_map_get_cpu_id(int cpu, struct coresight_trace_id_map *id_map)
155{
156	unsigned long flags;
157	int id;
158
159	spin_lock_irqsave(&id_map_lock, flags);
160
161	/* check for existing allocation for this CPU */
162	id = _coresight_trace_id_read_cpu_id(cpu);
163	if (id)
164		goto get_cpu_id_clr_pend;
165
166	/*
167	 * Find a new ID.
168	 *
169	 * Use legacy values where possible in the dynamic trace ID allocator to
170	 * allow older tools to continue working if they are not upgraded at the
171	 * same time as the kernel drivers.
172	 *
173	 * If the generated legacy ID is invalid, or not available then the next
174	 * available dynamic ID will be used.
175	 */
176	id = coresight_trace_id_alloc_new_id(id_map,
177					     CORESIGHT_LEGACY_CPU_TRACE_ID(cpu),
178					     false);
179	if (!IS_VALID_CS_TRACE_ID(id))
180		goto get_cpu_id_out_unlock;
181
182	/* allocate the new id to the cpu */
183	atomic_set(&per_cpu(cpu_id, cpu), id);
184
185get_cpu_id_clr_pend:
186	/* we are (re)using this ID - so ensure it is not marked for release */
187	cpumask_clear_cpu(cpu, &cpu_id_release_pending);
188	clear_bit(id, id_map->pend_rel_ids);
189
190get_cpu_id_out_unlock:
191	spin_unlock_irqrestore(&id_map_lock, flags);
192
193	DUMP_ID_CPU(cpu, id);
194	DUMP_ID_MAP(id_map);
195	return id;
196}
197
198static void coresight_trace_id_map_put_cpu_id(int cpu, struct coresight_trace_id_map *id_map)
199{
200	unsigned long flags;
201	int id;
202
203	/* check for existing allocation for this CPU */
204	id = _coresight_trace_id_read_cpu_id(cpu);
205	if (!id)
206		return;
207
208	spin_lock_irqsave(&id_map_lock, flags);
209
210	if (atomic_read(&perf_cs_etm_session_active)) {
211		/* set release at pending if perf still active */
212		coresight_trace_id_set_pend_rel(id, id_map);
213		cpumask_set_cpu(cpu, &cpu_id_release_pending);
214	} else {
215		/* otherwise clear id */
216		coresight_trace_id_free(id, id_map);
217		atomic_set(&per_cpu(cpu_id, cpu), 0);
218	}
219
220	spin_unlock_irqrestore(&id_map_lock, flags);
221	DUMP_ID_CPU(cpu, id);
222	DUMP_ID_MAP(id_map);
223}
224
225static int coresight_trace_id_map_get_system_id(struct coresight_trace_id_map *id_map)
226{
227	unsigned long flags;
228	int id;
229
230	spin_lock_irqsave(&id_map_lock, flags);
231	/* prefer odd IDs for system components to avoid legacy CPU IDS */
232	id = coresight_trace_id_alloc_new_id(id_map, 0, true);
233	spin_unlock_irqrestore(&id_map_lock, flags);
234
235	DUMP_ID(id);
236	DUMP_ID_MAP(id_map);
237	return id;
238}
239
240static void coresight_trace_id_map_put_system_id(struct coresight_trace_id_map *id_map, int id)
241{
242	unsigned long flags;
243
244	spin_lock_irqsave(&id_map_lock, flags);
245	coresight_trace_id_free(id, id_map);
246	spin_unlock_irqrestore(&id_map_lock, flags);
247
248	DUMP_ID(id);
249	DUMP_ID_MAP(id_map);
250}
251
252/* API functions */
253
254int coresight_trace_id_get_cpu_id(int cpu)
255{
256	return coresight_trace_id_map_get_cpu_id(cpu, &id_map_default);
257}
258EXPORT_SYMBOL_GPL(coresight_trace_id_get_cpu_id);
259
260void coresight_trace_id_put_cpu_id(int cpu)
261{
262	coresight_trace_id_map_put_cpu_id(cpu, &id_map_default);
263}
264EXPORT_SYMBOL_GPL(coresight_trace_id_put_cpu_id);
265
266int coresight_trace_id_read_cpu_id(int cpu)
267{
268	return _coresight_trace_id_read_cpu_id(cpu);
269}
270EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id);
271
272int coresight_trace_id_get_system_id(void)
273{
274	return coresight_trace_id_map_get_system_id(&id_map_default);
275}
276EXPORT_SYMBOL_GPL(coresight_trace_id_get_system_id);
277
278void coresight_trace_id_put_system_id(int id)
279{
280	coresight_trace_id_map_put_system_id(&id_map_default, id);
281}
282EXPORT_SYMBOL_GPL(coresight_trace_id_put_system_id);
283
284void coresight_trace_id_perf_start(void)
285{
286	atomic_inc(&perf_cs_etm_session_active);
287	PERF_SESSION(atomic_read(&perf_cs_etm_session_active));
288}
289EXPORT_SYMBOL_GPL(coresight_trace_id_perf_start);
290
291void coresight_trace_id_perf_stop(void)
292{
293	if (!atomic_dec_return(&perf_cs_etm_session_active))
294		coresight_trace_id_release_all_pending();
295	PERF_SESSION(atomic_read(&perf_cs_etm_session_active));
296}
297EXPORT_SYMBOL_GPL(coresight_trace_id_perf_stop);