1 files changed, 300 insertions, 0 deletions
diff --git a/drivers/hwtracing/coresight/coresight-trace-id.c b/drivers/hwtracing/coresight/coresight-trace-id.c
new file mode 100644
index 000000000000..7ed337d54d3e
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-trace-id.c
@@ -0,0 +1,300 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022, Linaro Limited, All rights reserved.
+ * Author: Mike Leach <mike.leach@linaro.org>
+ */
+#include <linux/coresight.h>
+#include <linux/coresight-pmu.h>
+#include <linux/cpumask.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include "coresight-trace-id.h"
+
+enum trace_id_flags {
+	TRACE_ID_ANY = 0x0,
+	TRACE_ID_PREFER_ODD = 0x1,
+	TRACE_ID_REQ_STATIC = 0x2,
+};
+
+/* Default trace ID map. Used in sysfs mode and for system sources */
+static DEFINE_PER_CPU(atomic_t, id_map_default_cpu_ids) = ATOMIC_INIT(0);
+static struct coresight_trace_id_map id_map_default = {
+	.cpu_map = &id_map_default_cpu_ids,
+	.lock = __RAW_SPIN_LOCK_UNLOCKED(id_map_default.lock)
+};
+
+/* #define TRACE_ID_DEBUG 1 */
+#if defined(TRACE_ID_DEBUG) || defined(CONFIG_COMPILE_TEST)
+
+static void coresight_trace_id_dump_table(struct coresight_trace_id_map *id_map,
+					  const char *func_name)
+{
+	pr_debug("%s id_map::\n", func_name);
+	pr_debug("Used = %*pb\n", CORESIGHT_TRACE_IDS_MAX, id_map->used_ids);
+}
+#define DUMP_ID_MAP(map)   coresight_trace_id_dump_table(map, __func__)
+#define DUMP_ID_CPU(cpu, id) pr_debug("%s called;  cpu=%d, id=%d\n", __func__, cpu, id)
+#define DUMP_ID(id)   pr_debug("%s called; id=%d\n", __func__, id)
+#define PERF_SESSION(n) pr_debug("%s perf count %d\n", __func__, n)
+#else
+#define DUMP_ID_MAP(map)
+#define DUMP_ID(id)
+#define DUMP_ID_CPU(cpu, id)
+#define PERF_SESSION(n)
+#endif
+
+/* unlocked read of current trace ID value for given CPU */
+static int _coresight_trace_id_read_cpu_id(int cpu, struct coresight_trace_id_map *id_map)
+{
+	return atomic_read(per_cpu_ptr(id_map->cpu_map, cpu));
+}
+
+/* look for next available odd ID, return 0 if none found */
+static int coresight_trace_id_find_odd_id(struct coresight_trace_id_map *id_map)
+{
+	int found_id = 0, bit = 1, next_id;
+
+	while ((bit < CORESIGHT_TRACE_ID_RES_TOP) && !found_id) {
+		/*
+		 * bitmap length of CORESIGHT_TRACE_ID_RES_TOP,
+		 * search from offset `bit`.
+		 */
+		next_id = find_next_zero_bit(id_map->used_ids,
+					     CORESIGHT_TRACE_ID_RES_TOP, bit);
+		if ((next_id < CORESIGHT_TRACE_ID_RES_TOP) && (next_id & 0x1))
+			found_id = next_id;
+		else
+			bit = next_id + 1;
+	}
+	return found_id;
+}
+
+/*
+ * Allocate new ID and set in use
+ *
+ * if @preferred_id is a valid id then try to use that value if available.
+ * if @preferred_id is not valid and @prefer_odd_id is true, try for odd id.
+ *
+ * Otherwise allocate next available ID.
+ */
+static int coresight_trace_id_alloc_new_id(struct coresight_trace_id_map *id_map,
+					   int preferred_id, unsigned int flags)
+{
+	int id = 0;
+
+	/* for backwards compatibility, cpu IDs may use preferred value */
+	if (IS_VALID_CS_TRACE_ID(preferred_id)) {
+		if (!test_bit(preferred_id, id_map->used_ids)) {
+			id = preferred_id;
+			goto trace_id_allocated;
+		} else if (flags & TRACE_ID_REQ_STATIC)
+			return -EBUSY;
+	} else if (flags & TRACE_ID_PREFER_ODD) {
+	/* may use odd ids to avoid preferred legacy cpu IDs */
+		id = coresight_trace_id_find_odd_id(id_map);
+		if (id)
+			goto trace_id_allocated;
+	} else if (!IS_VALID_CS_TRACE_ID(preferred_id) &&
+			(flags & TRACE_ID_REQ_STATIC))
+		return -EINVAL;
+
+	/*
+	 * skip reserved bit 0, look at bitmap length of
+	 * CORESIGHT_TRACE_ID_RES_TOP from offset of bit 1.
+	 */
+	id = find_next_zero_bit(id_map->used_ids, CORESIGHT_TRACE_ID_RES_TOP, 1);
+	if (id >= CORESIGHT_TRACE_ID_RES_TOP)
+		return -EINVAL;
+
+	/* mark as used */
+trace_id_allocated:
+	set_bit(id, id_map->used_ids);
+	return id;
+}
+
+static void coresight_trace_id_free(int id, struct coresight_trace_id_map *id_map)
+{
+	if (WARN(!IS_VALID_CS_TRACE_ID(id), "Invalid Trace ID %d\n", id))
+		return;
+	if (WARN(!test_bit(id, id_map->used_ids), "Freeing unused ID %d\n", id))
+		return;
+	clear_bit(id, id_map->used_ids);
+}
+
+/*
+ * Release all IDs and clear CPU associations.
+ */
+static void coresight_trace_id_release_all(struct coresight_trace_id_map *id_map)
+{
+	unsigned long flags;
+	int cpu;
+
+	raw_spin_lock_irqsave(&id_map->lock, flags);
+	bitmap_zero(id_map->used_ids, CORESIGHT_TRACE_IDS_MAX);
+	for_each_possible_cpu(cpu)
+		atomic_set(per_cpu_ptr(id_map->cpu_map, cpu), 0);
+	raw_spin_unlock_irqrestore(&id_map->lock, flags);
+	DUMP_ID_MAP(id_map);
+}
+
+static int _coresight_trace_id_get_cpu_id(int cpu, struct coresight_trace_id_map *id_map)
+{
+	unsigned long flags;
+	int id;
+
+	raw_spin_lock_irqsave(&id_map->lock, flags);
+
+	/* check for existing allocation for this CPU */
+	id = _coresight_trace_id_read_cpu_id(cpu, id_map);
+	if (id)
+		goto get_cpu_id_out_unlock;
+
+	/*
+	 * Find a new ID.
+	 *
+	 * Use legacy values where possible in the dynamic trace ID allocator to
+	 * allow older tools to continue working if they are not upgraded at the
+	 * same time as the kernel drivers.
+	 *
+	 * If the generated legacy ID is invalid, or not available then the next
+	 * available dynamic ID will be used.
+	 */
+	id = coresight_trace_id_alloc_new_id(id_map,
+					     CORESIGHT_LEGACY_CPU_TRACE_ID(cpu),
+					     TRACE_ID_ANY);
+	if (!IS_VALID_CS_TRACE_ID(id))
+		goto get_cpu_id_out_unlock;
+
+	/* allocate the new id to the cpu */
+	atomic_set(per_cpu_ptr(id_map->cpu_map, cpu), id);
+
+get_cpu_id_out_unlock:
+	raw_spin_unlock_irqrestore(&id_map->lock, flags);
+
+	DUMP_ID_CPU(cpu, id);
+	DUMP_ID_MAP(id_map);
+	return id;
+}
+
+static void _coresight_trace_id_put_cpu_id(int cpu, struct coresight_trace_id_map *id_map)
+{
+	unsigned long flags;
+	int id;
+
+	/* check for existing allocation for this CPU */
+	id = _coresight_trace_id_read_cpu_id(cpu, id_map);
+	if (!id)
+		return;
+
+	raw_spin_lock_irqsave(&id_map->lock, flags);
+
+	coresight_trace_id_free(id, id_map);
+	atomic_set(per_cpu_ptr(id_map->cpu_map, cpu), 0);
+
+	raw_spin_unlock_irqrestore(&id_map->lock, flags);
+	DUMP_ID_CPU(cpu, id);
+	DUMP_ID_MAP(id_map);
+}
+
+static int coresight_trace_id_map_get_system_id(struct coresight_trace_id_map *id_map,
+					int preferred_id, unsigned int traceid_flags)
+{
+	unsigned long flags;
+	int id;
+
+	raw_spin_lock_irqsave(&id_map->lock, flags);
+	id = coresight_trace_id_alloc_new_id(id_map, preferred_id, traceid_flags);
+	raw_spin_unlock_irqrestore(&id_map->lock, flags);
+
+	DUMP_ID(id);
+	DUMP_ID_MAP(id_map);
+	return id;
+}
+
+static void coresight_trace_id_map_put_system_id(struct coresight_trace_id_map *id_map, int id)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&id_map->lock, flags);
+	coresight_trace_id_free(id, id_map);
+	raw_spin_unlock_irqrestore(&id_map->lock, flags);
+
+	DUMP_ID(id);
+	DUMP_ID_MAP(id_map);
+}
+
+/* API functions */
+
+int coresight_trace_id_get_cpu_id(int cpu)
+{
+	return _coresight_trace_id_get_cpu_id(cpu, &id_map_default);
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_get_cpu_id);
+
+int coresight_trace_id_get_cpu_id_map(int cpu, struct coresight_trace_id_map *id_map)
+{
+	return _coresight_trace_id_get_cpu_id(cpu, id_map);
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_get_cpu_id_map);
+
+void coresight_trace_id_put_cpu_id(int cpu)
+{
+	_coresight_trace_id_put_cpu_id(cpu, &id_map_default);
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_put_cpu_id);
+
+void coresight_trace_id_put_cpu_id_map(int cpu, struct coresight_trace_id_map *id_map)
+{
+	_coresight_trace_id_put_cpu_id(cpu, id_map);
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_put_cpu_id_map);
+
+int coresight_trace_id_read_cpu_id(int cpu)
+{
+	return _coresight_trace_id_read_cpu_id(cpu, &id_map_default);
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id);
+
+int coresight_trace_id_read_cpu_id_map(int cpu, struct coresight_trace_id_map *id_map)
+{
+	return _coresight_trace_id_read_cpu_id(cpu, id_map);
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id_map);
+
+int coresight_trace_id_get_system_id(void)
+{
+	/* prefer odd IDs for system components to avoid legacy CPU IDS */
+	return coresight_trace_id_map_get_system_id(&id_map_default, 0,
+			TRACE_ID_PREFER_ODD);
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_get_system_id);
+
+int coresight_trace_id_get_static_system_id(int trace_id)
+{
+	return coresight_trace_id_map_get_system_id(&id_map_default,
+			trace_id, TRACE_ID_REQ_STATIC);
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_get_static_system_id);
+
+void coresight_trace_id_put_system_id(int id)
+{
+	coresight_trace_id_map_put_system_id(&id_map_default, id);
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_put_system_id);
+
+void coresight_trace_id_perf_start(struct coresight_trace_id_map *id_map)
+{
+	atomic_inc(&id_map->perf_cs_etm_session_active);
+	PERF_SESSION(atomic_read(&id_map->perf_cs_etm_session_active));
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_perf_start);
+
+void coresight_trace_id_perf_stop(struct coresight_trace_id_map *id_map)
+{
+	if (!atomic_dec_return(&id_map->perf_cs_etm_session_active))
+		coresight_trace_id_release_all(id_map);
+	PERF_SESSION(atomic_read(&id_map->perf_cs_etm_session_active));
+}
+EXPORT_SYMBOL_GPL(coresight_trace_id_perf_stop);