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Message-ID: <ef057e19-1209-4a72-b223-ef3f1e2b4513@arm.com>
Date: Mon, 18 Nov 2024 10:18:41 +0000
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Jinlong Mao <quic_jinlmao@...cinc.com>, Mike Leach
<mike.leach@...aro.org>, James Clark <james.clark@....com>,
Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v6 2/3] coresight: Add support to get static id for system
trace sources
On 18/11/2024 10:14, Jinlong Mao wrote:
>
>
> On 2024/11/13 21:27, Suzuki K Poulose wrote:
>> On 04/11/2024 11:56, 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_static_trace_id to get the fixed trace id from
>>> device node and pass id to coresight_trace_id_get_static_system_id to
>>> reserve the id.
>>>
>>> Signed-off-by: Mao Jinlong <quic_jinlmao@...cinc.com>
>>> Reviewed-by: Mike Leach <mike.leach@...aro.org>
>>> ---
>>> .../hwtracing/coresight/coresight-platform.c | 6 +++
>>> .../hwtracing/coresight/coresight-trace-id.c | 39 +++++++++++++------
>>> .../hwtracing/coresight/coresight-trace-id.h | 9 +++++
>>> include/linux/coresight.h | 1 +
>>> 4 files changed, 44 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/
>>> drivers/hwtracing/coresight/coresight-platform.c
>>> index 64e171eaad82..633d96b9577a 100644
>>> --- a/drivers/hwtracing/coresight/coresight-platform.c
>>> +++ b/drivers/hwtracing/coresight/coresight-platform.c
>>> @@ -796,6 +796,12 @@ int coresight_get_cpu(struct device *dev)
>>> }
>>> EXPORT_SYMBOL_GPL(coresight_get_cpu);
>>> +int coresight_get_static_trace_id(struct device *dev, u32 *id)
>>> +{
>>> + return fwnode_property_read_u32(dev_fwnode(dev), "arm,static-
>>> trace-id", id);
>>> +}
>>> +EXPORT_SYMBOL_GPL(coresight_get_static_trace_id);
>>> +
>>> struct coresight_platform_data *
>>> coresight_get_platform_data(struct device *dev)
>>> {
>>> diff --git a/drivers/hwtracing/coresight/coresight-trace-id.c b/
>>> drivers/hwtracing/coresight/coresight-trace-id.c
>>> index d98e12cb30ec..df8fe50b413f 100644
>>> --- a/drivers/hwtracing/coresight/coresight-trace-id.c
>>> +++ b/drivers/hwtracing/coresight/coresight-trace-id.c
>>> @@ -12,6 +12,12 @@
>>> #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 = {
>>> @@ -74,16 +80,18 @@ static int coresight_trace_id_find_odd_id(struct
>>> coresight_trace_id_map *id_map)
>>> * 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, unsigned int flags)
>>> {
>>> 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;
>>> - } else if (prefer_odd_id) {
>>> + 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 -EINVAL;
>>
>> nit: EBUSY sounds like a better choice here ? Requested ID is not
>> available.
>>
>> Additionally, do we need to handle a case where the preferred_id is
>> not valid ? I think we silently allocate a new trace id in such case ?
>>
>> Rest looks good to me.
>>
>> Suzuki
>>
>>
>
> If preferred_id is not valid, a random id will be allocated for the
> source. For the normal source, 0 is provided here as preferred_id.
My point is : If preferred_id is not valid *and* TRACE_ID_REQ_STATIC
flag is set, we go ahead and allocate a random different ID. Which is
not preferred. We should return -EINVAL in that case.
Suzuki
>
>>
>>
>>> + } 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)
>>> @@ -153,7 +161,7 @@ static int _coresight_trace_id_get_cpu_id(int
>>> cpu, struct coresight_trace_id_map
>>> */
>>> id = coresight_trace_id_alloc_new_id(id_map,
>>> CORESIGHT_LEGACY_CPU_TRACE_ID(cpu),
>>> - false);
>>> + TRACE_ID_ANY);
>>> if (!IS_VALID_CS_TRACE_ID(id))
>>> goto get_cpu_id_out_unlock;
>>> @@ -188,14 +196,14 @@ static void _coresight_trace_id_put_cpu_id(int
>>> cpu, struct coresight_trace_id_ma
>>> 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, unsigned int traceid_flags)
>>> {
>>> 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);
>>> + id = coresight_trace_id_alloc_new_id(id_map, preferred_id,
>>> traceid_flags);
>>> spin_unlock_irqrestore(&id_map->lock, flags);
>>> DUMP_ID(id);
>>> @@ -255,10 +263,19 @@
>>> EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id_map);
>>> int coresight_trace_id_get_system_id(void)
>>> {
>>> - return coresight_trace_id_map_get_system_id(&id_map_default);
>>> + /* 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);
>>> diff --git a/drivers/hwtracing/coresight/coresight-trace-id.h b/
>>> drivers/hwtracing/coresight/coresight-trace-id.h
>>> index 9aae50a553ca..db68e1ec56b6 100644
>>> --- a/drivers/hwtracing/coresight/coresight-trace-id.h
>>> +++ b/drivers/hwtracing/coresight/coresight-trace-id.h
>>> @@ -116,6 +116,15 @@ int coresight_trace_id_read_cpu_id_map(int cpu,
>>> struct coresight_trace_id_map *i
>>> */
>>> int coresight_trace_id_get_system_id(void);
>>> +/**
>>> + * Allocate a CoreSight static trace ID for a system component.
>>> + *
>>> + * Used to allocate static IDs for system trace sources such as
>>> dummy source.
>>> + *
>>> + * return: Trace ID or -EINVAL if allocation is impossible.
>>> + */
>>> +int coresight_trace_id_get_static_system_id(int id);
>>> +
>>> /**
>>> * Release an allocated system trace ID.
>>> *
>>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>>> index c13342594278..129795873072 100644
>>> --- a/include/linux/coresight.h
>>> +++ b/include/linux/coresight.h
>>> @@ -662,6 +662,7 @@ 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_static_trace_id(struct device *dev, u32 *id);
>>> struct coresight_platform_data *coresight_get_platform_data(struct
>>> device *dev);
>>> struct coresight_connection *
>>
>
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