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Message-ID: <6424c536-2f2c-4a59-8b6d-f610201dc7a7@arm.com>
Date: Wed, 13 Nov 2024 13:27:05 +0000
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Mao Jinlong <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 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
> + } 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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