linux-kernel - Re: [PATCH v2 3/3] coresight-tpdm: Add support to enable the lane for MCMB TPDM

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Message-ID: <8ca3d31b-74a0-497a-9b53-dfe9becd0f7a@arm.com>
Date: Tue, 17 Dec 2024 14:55:10 +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@...aro.org>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Tao Zhang <quic_taozha@...cinc.com>, coresight@...ts.linaro.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 3/3] coresight-tpdm: Add support to enable the lane for
 MCMB TPDM

On 05/11/2024 12:39, Mao Jinlong wrote:
> From: Tao Zhang <quic_taozha@...cinc.com>
> 
> Add the sysfs file to set/get the enablement of the lane. For MCMB
> configurations, the field "E_LN" in CMB_CR register is the
> individual lane enables. MCMB lane N is enabled for trace
> generation when M_CMB_CR.E=1 and M_CMB_CR.E_LN[N]=1. For lanes
> that are not implemented on a given MCMB configuration, the
> corresponding bits of this field read as 0 and ignore writes.
> 
> Signed-off-by: Tao Zhang <quic_taozha@...cinc.com>
> Signed-off-by: Mao Jinlong <quic_jinlmao@...cinc.com>
> ---
>   .../testing/sysfs-bus-coresight-devices-tpdm  |  7 +++++
>   drivers/hwtracing/coresight/coresight-tpdm.c  | 29 +++++++++++++++++++
>   drivers/hwtracing/coresight/coresight-tpdm.h  |  3 ++
>   3 files changed, 39 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> index e833edfec79e..fcc2a8f1f17f 100644
> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> @@ -265,3 +265,10 @@ Contact:	Tao Zhang (QUIC) <quic_taozha@...cinc.com>
>   Description:
>   		(RW) Set/Get which lane participates in the output pattern
>   		match cross trigger mechanism for the MCMB subunit TPDM.
> +
> +What:		/sys/bus/coresight/devices/<tpdm-name>/mcmb_lanes_select
> +Date:		Nov 2024
> +KernelVersion	6.13

6.14

Suzuki


> +Contact:	Tao Zhang (QUIC) <quic_taozha@...cinc.com>
> +Description:
> +		(RW) Set/Get the enablement of the individual lane.
> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c b/drivers/hwtracing/coresight/coresight-tpdm.c
> index 2e4dc86b03ea..bb0d6505ec9f 100644
> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
> @@ -1063,6 +1063,34 @@ static ssize_t mcmb_trig_lane_store(struct device *dev,
>   }
>   static DEVICE_ATTR_RW(mcmb_trig_lane);
>   
> +static ssize_t mcmb_lanes_select_show(struct device *dev,
> +				      struct device_attribute *attr,
> +				      char *buf)
> +{
> +	struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> +
> +	return sysfs_emit(buf, "%u\n",
> +			  (unsigned int)drvdata->cmb->mcmb.lane_select);
> +}
> +
> +static ssize_t mcmb_lanes_select_store(struct device *dev,
> +				       struct device_attribute *attr,
> +				       const char *buf,
> +				       size_t size)
> +{
> +	struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> +	unsigned long val;
> +
> +	if (kstrtoul(buf, 0, &val) || (val & ~TPDM_MCMB_E_LN_MASK))
> +		return -EINVAL;
> +
> +	guard(spinlock)(&drvdata->spinlock);
> +	drvdata->cmb->mcmb.lane_select = val & TPDM_MCMB_E_LN_MASK;
> +
> +	return size;
> +}
> +static DEVICE_ATTR_RW(mcmb_lanes_select);
> +
>   static struct attribute *tpdm_dsb_edge_attrs[] = {
>   	&dev_attr_ctrl_idx.attr,
>   	&dev_attr_ctrl_val.attr,
> @@ -1227,6 +1255,7 @@ static struct attribute *tpdm_cmb_msr_attrs[] = {
>   
>   static struct attribute *tpdm_mcmb_attrs[] = {
>   	&dev_attr_mcmb_trig_lane.attr,
> +	&dev_attr_mcmb_lanes_select.attr,
>   	NULL,
>   };
>   
> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.h b/drivers/hwtracing/coresight/coresight-tpdm.h
> index aa9746b2e77f..a80f3d680995 100644
> --- a/drivers/hwtracing/coresight/coresight-tpdm.h
> +++ b/drivers/hwtracing/coresight/coresight-tpdm.h
> @@ -48,6 +48,9 @@
>   /* MAX lanes in the output pattern for MCMB configurations*/
>   #define TPDM_MCMB_MAX_LANES 8
>   
> +/* Filter bit 0~7 from the value for CR_E_LN */
> +#define TPDM_MCMB_E_LN_MASK		GENMASK(7, 0)
> +
>   /* DSB Subunit Registers */
>   #define TPDM_DSB_CR		(0x780)
>   #define TPDM_DSB_TIER		(0x784)