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Date:   Mon, 22 Feb 2021 11:50:55 -0700
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Mike Leach <mike.leach@linaro.org>
Cc:     linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org,
        linux-doc@vger.kernel.org, suzuki.poulose@arm.com,
        yabinc@google.com, corbet@lwn.net, leo.yan@linaro.org,
        alexander.shishkin@linux.intel.com, tingwei@codeaurora.org,
        gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 01/10] coresight: syscfg: Initial coresight system
 configuration
Message-ID: <20210222185055.GA3239381@xps15>
References: <20210128170936.9222-1-mike.leach@linaro.org>
 <20210128170936.9222-2-mike.leach@linaro.org>
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In-Reply-To: <20210128170936.9222-2-mike.leach@linaro.org>
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On Thu, Jan 28, 2021 at 05:09:27PM +0000, Mike Leach wrote:
> Creates an system management API to allow complex configurations and
> features to be programmed into a CoreSight infrastructure.
> 
> A feature is defined as a programming set for a device or class of
> devices.
> 
> A configuration is a set of features across the system that are enabled
> for a trace session.
> 
> The API will manage system wide configuration, and allow complex
> programmed features to be added to individual device instances, and
> provide for system wide configuration selection on trace capture
> operations.
> 
> This patch creates the initial data object and the initial API for
> loading configurations and features.
> 
> Signed-off-by: Mike Leach <mike.leach@linaro.org>
> ---
>  drivers/hwtracing/coresight/Makefile          |   2 +-
>  .../hwtracing/coresight/coresight-config.h    | 167 +++++++++++++++
>  drivers/hwtracing/coresight/coresight-core.c  |  12 +-
>  .../hwtracing/coresight/coresight-etm-perf.c  |   2 +-
>  .../hwtracing/coresight/coresight-etm-perf.h  |   2 +-
>  .../hwtracing/coresight/coresight-syscfg.c    | 197 ++++++++++++++++++
>  .../hwtracing/coresight/coresight-syscfg.h    |  54 +++++
>  7 files changed, 432 insertions(+), 4 deletions(-)
>  create mode 100644 drivers/hwtracing/coresight/coresight-config.h
>  create mode 100644 drivers/hwtracing/coresight/coresight-syscfg.c
>  create mode 100644 drivers/hwtracing/coresight/coresight-syscfg.h
> 
> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> index f20e357758d1..4ce854c434b1 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -4,7 +4,7 @@
>  #
>  obj-$(CONFIG_CORESIGHT) += coresight.o
>  coresight-y := coresight-core.o  coresight-etm-perf.o coresight-platform.o \
> -		coresight-sysfs.o
> +		coresight-sysfs.o coresight-syscfg.o
>  obj-$(CONFIG_CORESIGHT_LINK_AND_SINK_TMC) += coresight-tmc.o
>  coresight-tmc-y := coresight-tmc-core.o coresight-tmc-etf.o \
>  		      coresight-tmc-etr.o
> diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
> new file mode 100644
> index 000000000000..3fedf8ab3cee
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-config.h
> @@ -0,0 +1,167 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2020 Linaro Limited, All rights reserved.
> + * Author: Mike Leach <mike.leach@linaro.org>
> + */
> +
> +#ifndef _CORESIGHT_CORESIGHT_CONFIG_H
> +#define _CORESIGHT_CORESIGHT_CONFIG_H
> +
> +#include <linux/coresight.h>
> +#include <linux/types.h>
> +
> +/* CoreSight Configuration Management - component and system wide configuration */
> +
> +/*
> + * Register type flags for register value descriptor:
> + * describe how the value is interpreted, and handled.
> + */
> +#define CS_CFG_REG_TYPE_STD		0x80	/* reg is standard reg */
> +#define CS_CFG_REG_TYPE_RESOURCE	0x40	/* reg is a resource */
> +#define CS_CFG_REG_TYPE_VAL_PARAM	0x08	/* reg value uses param */
> +#define CS_CFG_REG_TYPE_VAL_MASK	0x04	/* reg value bit masked */
> +#define CS_CFG_REG_TYPE_VAL_64BIT	0x02	/* reg value 64 bit */
> +#define CS_CFG_REG_TYPE_VAL_SAVE	0x01	/* reg value save on disable */
> +
> +/*
> + * flags defining what device class a feature will match to when processing a
> + * system configuration - used by config data and devices.
> + */
> +#define	CS_CFG_MATCH_CLASS_SRC_ALL	0x0001	/* match any source */
> +#define CS_CFG_MATCH_CLASS_SRC_ETM4	0x0002	/* match any ETMv4 device */
> +
> +/* flags defining device instance matching - used in config match desc data. */
> +#define CS_CFG_MATCH_INST_ANY		0x80000000 /* any instance of a class */
> +
> +/*
> + * Limit number of presets in a configuration
> + * This is related to the number of bits (4) we use to select the preset on
> + * the perf command line. Preset 0 is always none selected.
> + * See PMU_FORMAT_ATTR(preset, "config:0-3") in coresight-etm-perf.c
> + */
> +#define CS_CFG_CONFIG_PRESET_MAX 15
> +
> +/**
> + * Parameter descriptor for a device feature.
> + *
> + * @name:  Name of parameter.
> + * @value: Initial or default value.
> + */
> +struct cscfg_parameter_desc {
> +	const char *name;
> +	u64 value;
> +};
> +
> +/**
> + * Representation of register value.
> + *
> + * Supports full 64 bit register value, or 32 bit value with optional mask
> + * value.
> + *
> + * @type:	define register usage and interpretation.
> + * @offset:	the address offset for register in the hardware device (per device specification).
> + * @hw_info:	optional hardware device type specific information. (ETM / CTI specific etc)
> + * @val64:	64 bit value.
> + * @val32:	32 bit value.
> + * @mask32:	32 bit mask when using 32 bit value to access device register.
> + */
> +struct cscfg_regval_desc {
> +	struct {
> +		u32 type:8;
> +		u32 offset:12;
> +		u32 hw_info:12;
> +	};
> +	union {
> +		u64 val64;
> +		struct {
> +			u32 val32;
> +			u32 mask32;
> +		};
> +	};
> +};
> +
> +/**
> + * Device feature descriptor - combination of registers and parameters to
> + * program a device to implement a specific complex function.
> + *
> + * @name:	feature name.
> + * @brief:	brief description of the feature.
> + * @item:	List entry.
> + * @match_flags: matching information if loading into a device
> + * @nr_params:  number of parameters used.
> + * @params:	array of parameters used.
> + * @nr_regs:	number of registers used.
> + * @reg:	array of registers used.
> + */
> +struct cscfg_feature_desc {
> +	const char *name;
> +	const char *brief;
> +	struct list_head item;
> +	u32 match_flags;
> +	int nr_params;
> +	struct cscfg_parameter_desc *params;

	struct cscfg_parameter_desc *params_desc;

> +	int nr_regs;
> +	struct cscfg_regval_desc *regs;

        struct cscfg_regval_desc *regs_desc;

That way I know exactly what I'm looking at when I see something like the
following in patch 03:

        reg_desc = &feat->desc->regs[i];