On 03/06/2024 11:04, James Clark wrote:

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);

Actually, even better we can have an "int flags" argument rather than having to work out what a load of booleans mean. And then use these:

TRACE_ID_WANT_ODD | TRACE_ID_WANT_PREFERRED

flags = TRACE_ID_WANT_ODD flags |= preferred_id > 0 ? TRACE_ID_WANT_PREFERRED : 0; coresight_trace_id_alloc_new_id(id_map, preferred_id, flags);

...

• } 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 *

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

Some dummy source has static trace id configured in HW and it cannot be changed via software programming. Configure the trace id in device tree and reserve the id when device probe.

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

.../sysfs-bus-coresight-devices-dummy-source | 15 +++++ drivers/hwtracing/coresight/coresight-dummy.c | 58 +++++++++++++++++-- 2 files changed, 69 insertions(+), 4 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source

diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source b/Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source new file mode 100644 index 000000000000..d93c198115c9 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source @@ -0,0 +1,15 @@ +What: /sys/bus/coresight/devices/dummy_source<N>/enable_source +Date: June 2024 +KernelVersion: 6.9 +Contact: Mao Jinlong quic_jinlmao@quicinc.com +Description: (RW) Enable/disable tracing of dummy source. A sink should be activated

• before enabling the source. The path of coresight components linking
  

• the source to the sink is configured and managed automatically by the
  

• coresight framework.
  

+What: /sys/bus/coresight/devices/dummy_source<N>/traceid +Date: June 2024 +KernelVersion: 6.9 +Contact: Mao Jinlong quic_jinlmao@quicinc.com +Description: (R) Show the trace ID that will appear in the trace stream

• coming from this trace entity.
  

diff --git a/drivers/hwtracing/coresight/coresight-dummy.c b/drivers/hwtracing/coresight/coresight-dummy.c index ac70c0b491be..1f7133ac2c0b 100644 --- a/drivers/hwtracing/coresight/coresight-dummy.c +++ b/drivers/hwtracing/coresight/coresight-dummy.c @@ -11,10 +11,12 @@ #include <linux/pm_runtime.h> #include "coresight-priv.h" +#include "coresight-trace-id.h" struct dummy_drvdata { struct device *dev; struct coresight_device *csdev;

• u8 traceid;

}; DEFINE_CORESIGHT_DEVLIST(source_devs, "dummy_source"); @@ -67,6 +69,32 @@ static const struct coresight_ops dummy_sink_cs_ops = { .sink_ops = &dummy_sink_ops, }; +/* User can get the trace id of dummy source from this node. */ +static ssize_t traceid_show(struct device *dev,

• 	    struct device_attribute *attr, char *buf)
  

+{

• unsigned long val;
• struct dummy_drvdata *drvdata = dev_get_drvdata(dev->parent);
• val = drvdata->traceid;
• return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);

+} +static DEVICE_ATTR_RO(traceid);

+static struct attribute *coresight_dummy_attrs[] = {

• &dev_attr_traceid.attr,
• NULL,

+};

+static const struct attribute_group coresight_dummy_group = {

• .attrs = coresight_dummy_attrs,

+};

+static const struct attribute_group *coresight_dummy_groups[] = {

• &coresight_dummy_group,
• NULL,

+};

static int dummy_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; @@ -74,6 +102,11 @@ static int dummy_probe(struct platform_device *pdev) struct coresight_platform_data *pdata; struct dummy_drvdata *drvdata; struct coresight_desc desc = { 0 };

• int ret, trace_id;
• drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
• if (!drvdata)

• return -ENOMEM;
  

if (of_device_is_compatible(node, "arm,coresight-dummy-source")) { @@ -85,6 +118,24 @@ static int dummy_probe(struct platform_device *pdev) desc.subtype.source_subtype = CORESIGHT_DEV_SUBTYPE_SOURCE_OTHERS; desc.ops = &dummy_source_cs_ops;

• desc.groups = coresight_dummy_groups;
  

• ret = coresight_get_source_traceid(dev, &trace_id);
  

• if (!ret) {
  

• 	ret = coresight_trace_id_get_system_id(trace_id);
  

• 	if (ret < 0)
  

• 		return ret;
  

• 	drvdata->traceid = ret;
  

• } else {
  

• 	trace_id = coresight_trace_id_get_system_id(0);
  

• 	if (trace_id < 0) {
  

• 		ret = trace_id;
  

• 		return ret;
  

• 	}
  

• 	drvdata->traceid = (u8)trace_id;
  

• }
  

It's a bit weird to use ret in one version and trace_id in the other. And one casts to (u8) but the other doesn't. I'm sure it all compiles to the same in the end but it would be a bit more readable if it was more consistent.

} else if (of_device_is_compatible(node, "arm,coresight-dummy-sink")) { desc.name = coresight_alloc_device_name(&sink_devs, dev); if (!desc.name) @@ -103,10 +154,6 @@ static int dummy_probe(struct platform_device *pdev) return PTR_ERR(pdata); pdev->dev.platform_data = pdata;

• drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
• if (!drvdata)

• return -ENOMEM;
  

• drvdata->dev = &pdev->dev; platform_set_drvdata(pdev, drvdata);

@@ -126,7 +173,10 @@ static void dummy_remove(struct platform_device *pdev) { struct dummy_drvdata *drvdata = platform_get_drvdata(pdev); struct device *dev = &pdev->dev;

• struct device_node *node = dev->of_node;

• if (of_device_is_compatible(node, "arm,coresight-dummy-source"))

• coresight_trace_id_put_system_id(drvdata->traceid);
  

  pm_runtime_disable(dev); coresight_unregister(drvdata->csdev);

}