Re: [PATCH v2 2/3] coresight: Add support to get preferred id for system trace sources

On 03/06/2024 10:43, Mao Jinlong wrote:

Dynamic trace id was introduced in coresight subsystem, so trace id is allocated dynamically. However, some hardware ATB source has static trace id and it cannot be changed via software programming. For such source, it can call coresight_get_source_traceid to get the fixed trace id from device node and pass id to coresight_trace_id_get_system_id to reserve the id.

Signed-off-by: Mao Jinlong quic_jinlmao@quicinc.com

.../hwtracing/coresight/coresight-platform.c | 26 +++++++++++++++ drivers/hwtracing/coresight/coresight-stm.c | 2 +- .../hwtracing/coresight/coresight-trace-id.c | 32 ++++++++++++------- .../hwtracing/coresight/coresight-trace-id.h | 5 ++- include/linux/coresight.h | 1 + 5 files changed, 53 insertions(+), 13 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c index 9d550f5697fa..8dd3cbd676b8 100644 --- a/drivers/hwtracing/coresight/coresight-platform.c +++ b/drivers/hwtracing/coresight/coresight-platform.c @@ -183,6 +183,17 @@ static int of_coresight_get_cpu(struct device *dev) return cpu; } +/*

• • of_coresight_get_trace_id: Get the atid of a source device.
• • Returns 0 on success.
• */

+static int of_coresight_get_trace_id(struct device *dev, u32 *id) +{

• return of_property_read_u32(dev->of_node, "trace-id", id);

+}

/*

• of_coresight_parse_endpoint : Parse the given output endpoint @ep
• and fill the connection information in @pdata->out_conns

@@ -782,6 +793,12 @@ static inline int acpi_coresight_get_cpu(struct device *dev) { return -ENODEV; }

+static int of_coresight_get_trace_id(struct device *dev, u32 *id) +{

• return -ENODEV;

+}

#endif int coresight_get_cpu(struct device *dev) @@ -794,6 +811,15 @@ int coresight_get_cpu(struct device *dev) } EXPORT_SYMBOL_GPL(coresight_get_cpu); +int coresight_get_source_traceid(struct device *dev, u32 *id) +{

• if (!is_of_node(dev->fwnode))

• return -EINVAL;
  

• return of_coresight_get_trace_id(dev, id);

+} +EXPORT_SYMBOL_GPL(coresight_get_source_traceid);

struct coresight_platform_data * coresight_get_platform_data(struct device *dev) { diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c index e1c62820dfda..802f9e4ae570 100644 --- a/drivers/hwtracing/coresight/coresight-stm.c +++ b/drivers/hwtracing/coresight/coresight-stm.c @@ -901,7 +901,7 @@ static int __stm_probe(struct device *dev, struct resource *res) goto stm_unregister; }

• trace_id = coresight_trace_id_get_system_id();

• trace_id = coresight_trace_id_get_system_id(0);

I would #define 0 to "TRACE_ID_ANY" or something like that so it's obvious what it means.

if (trace_id < 0) { ret = trace_id; goto cs_unregister; diff --git a/drivers/hwtracing/coresight/coresight-trace-id.c b/drivers/hwtracing/coresight/coresight-trace-id.c index af5b4ef59cea..5c25c75a2f08 100644 --- a/drivers/hwtracing/coresight/coresight-trace-id.c +++ b/drivers/hwtracing/coresight/coresight-trace-id.c @@ -75,20 +75,23 @@ static int coresight_trace_id_find_odd_id(struct coresight_trace_id_map *id_map)

• Allocate new ID and set in use
• if @preferred_id is a valid id then try to use that value if available.

• • if @only_preferred is true, if @preferred_id is used, return error EINVAL.

if @only_preferred is true @preferred_id must be free, otherwise return error -EINVAL

• 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, bool prefer_odd_id)
  

• 	   int preferred_id, bool prefer_odd_id, bool only_preferred)
  

{ int id = 0; /* for backwards compatibility, cpu IDs may use preferred value */

• if (IS_VALID_CS_TRACE_ID(preferred_id) &&

•    !test_bit(preferred_id, id_map->used_ids)) {
  

• id = preferred_id;
  

• goto trace_id_allocated;
  

• 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 (WARN(only_preferred, "Trace ID %d is used.\n", preferred_id))
  

• 	return -EINVAL;
  

  } else if (prefer_odd_id) { /* may use odd ids to avoid preferred legacy cpu IDs */ id = coresight_trace_id_find_odd_id(id_map);

@@ -175,7 +178,7 @@ static int coresight_trace_id_map_get_cpu_id(int cpu, struct coresight_trace_id_ */ id = coresight_trace_id_alloc_new_id(id_map, CORESIGHT_LEGACY_CPU_TRACE_ID(cpu),

• 			     false);
  

• 			     false, false);
  

  if (!IS_VALID_CS_TRACE_ID(id)) goto get_cpu_id_out_unlock;

@@ -222,14 +225,21 @@ static void coresight_trace_id_map_put_cpu_id(int cpu, struct coresight_trace_id DUMP_ID_MAP(id_map); } -static int coresight_trace_id_map_get_system_id(struct coresight_trace_id_map *id_map) +static int coresight_trace_id_map_get_system_id(struct coresight_trace_id_map *id_map,

• 		int preferred_id, bool only_preferred)
  

Looks like "only_preferred" was left on here by mistake and it's not used. For this function preferred_id != 0 means the same.

{ unsigned long flags; int id; spin_lock_irqsave(&id_map_lock, flags);

• /* prefer odd IDs for system components to avoid legacy CPU IDS */
• id = coresight_trace_id_alloc_new_id(id_map, 0, true);

• if (preferred_id > 0) {

• /* use preferred id if it is available */
  

• id = coresight_trace_id_alloc_new_id(id_map, preferred_id, false, true);
  

• } else {

• /* prefer odd IDs for system components to avoid legacy CPU IDS */
  

• id = coresight_trace_id_alloc_new_id(id_map, 0, true, false);
  

prefer_odd_id is different in each of these calls which I think is a mistake?

You could do one function call to avoid that:

only_preferred = preferred_id > 0 coresight_trace_id_alloc_new_id(id_map, preferred_id, true, only_preferred);

• } spin_unlock_irqrestore(&id_map_lock, flags);

DUMP_ID(id); @@ -269,9 +279,9 @@ int coresight_trace_id_read_cpu_id(int cpu) } EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id); -int coresight_trace_id_get_system_id(void) +int coresight_trace_id_get_system_id(int id) {

• return coresight_trace_id_map_get_system_id(&id_map_default);

• return coresight_trace_id_map_get_system_id(&id_map_default, id, true);

} EXPORT_SYMBOL_GPL(coresight_trace_id_get_system_id); diff --git a/drivers/hwtracing/coresight/coresight-trace-id.h b/drivers/hwtracing/coresight/coresight-trace-id.h index 3797777d367e..9189a33c5857 100644 --- a/drivers/hwtracing/coresight/coresight-trace-id.h +++ b/drivers/hwtracing/coresight/coresight-trace-id.h @@ -118,9 +118,12 @@ int coresight_trace_id_read_cpu_id(int cpu);

• Used to allocate IDs for system trace sources such as STM.

• • @id: Preferred id value. If id is 0, get a free id from id map. If id is greater

0 -> TRACE_ID_ANY

• •  than 0, get a preferred id.
    

• • return: Trace ID or -EINVAL if allocation is impossible.
  */

-int coresight_trace_id_get_system_id(void); +int coresight_trace_id_get_system_id(int id); /**

• Release an allocated system trace ID.

diff --git a/include/linux/coresight.h b/include/linux/coresight.h index f09ace92176e..0599303be326 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -643,6 +643,7 @@ void coresight_relaxed_write64(struct coresight_device *csdev, void coresight_write64(struct coresight_device *csdev, u64 val, u32 offset); extern int coresight_get_cpu(struct device *dev); +extern int coresight_get_source_traceid(struct device *dev, u32 *id); struct coresight_platform_data *coresight_get_platform_data(struct device *dev); struct coresight_connection *