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Message-ID: <6a8e10fc-a231-467a-8056-d291e237fec1@quicinc.com>
Date: Mon, 18 Nov 2024 18:14:36 +0800
From: Jinlong Mao <quic_jinlmao@...cinc.com>
To: Suzuki K Poulose <suzuki.poulose@....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 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.
>
>
>> + } 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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