Re: [PATCH v4 03/10] coresight: config: Add configuration and feature generic functions

From: Mathieu Poirier
Date: Mon Feb 22 2021 - 17:58:36 EST

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On Thu, Jan 28, 2021 at 05:09:29PM +0000, Mike Leach wrote:
> Adds a set of generic support functions that allow devices to set and save
> features values on the device, and enable and disable configurations.
>
> Additional functions for other common operations including feature
> reset.
>
> Signed-off-by: Mike Leach <mike.leach@xxxxxxxxxx>
> ---
> drivers/hwtracing/coresight/Makefile | 2 +-
> .../hwtracing/coresight/coresight-config.c | 245 ++++++++++++++++++
> .../hwtracing/coresight/coresight-config.h | 14 +-
> .../hwtracing/coresight/coresight-syscfg.c | 5 +-
> 4 files changed, 262 insertions(+), 4 deletions(-)
> create mode 100644 drivers/hwtracing/coresight/coresight-config.c
>
> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> index 4ce854c434b1..daad9f103a78 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -4,7 +4,7 @@
> #
> obj-$(CONFIG_CORESIGHT) += coresight.o
> coresight-y := coresight-core.o coresight-etm-perf.o coresight-platform.o \
> - coresight-sysfs.o coresight-syscfg.o
> + coresight-sysfs.o coresight-syscfg.o coresight-config.o
> obj-$(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.c b/drivers/hwtracing/coresight/coresight-config.c
> new file mode 100644
> index 000000000000..6cc4b213d9b6
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-config.c
> @@ -0,0 +1,245 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright(C) 2020 Linaro Limited. All rights reserved.
> + * Author: Mike Leach <mike.leach@xxxxxxxxxx>
> + */
> +
> +#include <linux/sysfs.h>
> +#include "coresight-config.h"
> +#include "coresight-priv.h"
> +
> +/*
> + * Write the value held in the register structure into the driver internal memory
> + * location.
> + */
> +static void cscfg_set_reg(struct cscfg_reg_csdev *reg)
> +{
> + u32 *p_val32 = (u32 *)reg->drv_store;
> + u32 tmp32 = reg->value.val32;
> +
> + if (reg->value.type & CS_CFG_REG_TYPE_VAL_64BIT) {
> + *((u64 *)reg->drv_store) = reg->value.val64;
> + return;
> + }
> +
> + if (reg->value.type & CS_CFG_REG_TYPE_VAL_MASK) {
> + tmp32 = *p_val32;
> + tmp32 &= ~reg->value.mask32;
> + tmp32 |= reg->value.val32 & reg->value.mask32;
> + }
> + *p_val32 = tmp32;
> +}
> +
> +/*
> + * Read the driver value into the reg if this is marked as one we want to save.
> + */
> +static void cscfg_save_reg(struct cscfg_reg_csdev *reg)
> +{
> + if (!(reg->value.type & CS_CFG_REG_TYPE_VAL_SAVE))
> + return;
> + if (reg->value.type & CS_CFG_REG_TYPE_VAL_64BIT)
> + reg->value.val64 = *(u64 *)(reg->drv_store);
> + else
> + reg->value.val32 = *(u32 *)(reg->drv_store);
> +}
> +
> +static void cscfg_init_reg_param(struct cscfg_parameter_csdev *param_csdev,
> + struct cscfg_reg_csdev *reg_csdev)
> +{
> + param_csdev->reg = reg_csdev;

This is the link between registers and parameters... Very important and very
easy to miss. I'm not use how the situation can be improved other than adding a
comment to highlight the dependency.

> + param_csdev->val64 = reg_csdev->value.type & CS_CFG_REG_TYPE_VAL_64BIT;
> +
> + if (param_csdev->val64)
> + param_csdev->reg->value.val64 = param_csdev->current_value;
> + else
> + param_csdev->reg->value.val32 = (u32)param_csdev->current_value;
> +}
> +
> +/* set values into the driver locations referenced in cscfg_reg_csdev */
> +static int cscfg_set_on_enable(struct cscfg_feature_csdev *feat)
> +{
> + int i;
> +
> + spin_lock(feat->csdev_spinlock);
> + for (i = 0; i < feat->nr_regs; i++)
> + cscfg_set_reg(&feat->regs[i]);
> + spin_unlock(feat->csdev_spinlock);
> + dev_dbg(&feat->csdev->dev, "Feature %s: %s", feat->desc->name, "set on enable");
> + return 0;
> +}
> +
> +/* copy back values from the driver locations referenced in cscfg_reg_csdev */
> +static void cscfg_save_on_disable(struct cscfg_feature_csdev *feat)

static void cscfg_save_on_disable(struct cscfg_feature_csdev *feat_csdev)

To be modified throughout the patchset.

> +{
> + int i;
> +
> + spin_lock(feat->csdev_spinlock);
> + for (i = 0; i < feat->nr_regs; i++)
> + cscfg_save_reg(&feat->regs[i]);
> + spin_unlock(feat->csdev_spinlock);
> + dev_dbg(&feat->csdev->dev, "Feature %s: %s", feat->desc->name, "save on disable");
> +}
> +
> +/* default reset - restore default values */
> +void cscfg_reset_feat(struct cscfg_feature_csdev *feat)
> +{
> + struct cscfg_parameter_csdev *param_csdev;
> + struct cscfg_regval_desc *reg_desc;
> + struct cscfg_reg_csdev *reg_csdev;
> + int i;
> +
> + /*
> + * set the default values for all parameters and regs from the
> + * relevant static descriptors.
> + */
> + for (i = 0; i < feat->nr_params; i++)
> + feat->params[i].current_value = feat->desc->params[i].value;
> +
> + for (i = 0; i < feat->nr_regs; i++) {
> + reg_desc = &feat->desc->regs[i];
> + reg_csdev = &feat->regs[i];
> + reg_csdev->value.type = reg_desc->type;
> +
> + /* check if reg set from a parameter otherwise desc default */
> + if (reg_desc->type & CS_CFG_REG_TYPE_VAL_PARAM) {
> + /* for param, reg_desc->val32 is an index */

Overloading reg_desc->val32 into an index will make maintenance of this code
impossible. Please see if there is a way to make that more intuitive.

> + param_csdev = &feat->params[reg_desc->val32];
> + cscfg_init_reg_param(param_csdev, reg_csdev);
> + } else
> + reg_csdev->value.val64 = reg_desc->val64;

Very subtle how 32 bit values and mask are also handle by the above line.
Probably worth a comment.

> + }
> +}
> +
> +static int cscfg_update_presets(struct cscfg_config_csdev *cfg, int preset)

static int cscfg_update_presets(struct cscfg_config_csdev *cfg_csdev, ...

And throughout the patchset.

> +{
> + int i, j, line_offset = 0, val_idx = 0, max_idx;
> + struct cscfg_parameter_csdev *param;
> + struct cscfg_feature_csdev *feat;
> + const char *name;
> + u64 val;
> +
> + if (preset > cfg->desc->nr_presets)
> + return -EINVAL;

A preset < 0 should also be treated as an error.

> + /*
> + * Go through the array of features, assigning preset values to
> + * feature parameters in the order they appear.
> + * There should be precisely the same number of preset values as the
> + * sum of number of parameters over all the features - but we will
> + * ensure there is no overrun.
> + */
> + line_offset = (preset-1) * cfg->desc->nr_total_params;

line_offset = (preset - 1) * cfg->desc->nr_total_params;

> + max_idx = cfg->desc->nr_total_params;
> + for (i = 0; i < cfg->nr_feat; i++) {
> + feat = cfg->feats[i];
> + if (!feat->nr_params)
> + continue;
> +
> + for (j = 0; j < feat->nr_params; j++) {
> + param = &feat->params[j];
> + name = feat->desc->params[j].name;
> + val = cfg->desc->presets[line_offset + val_idx++];
> + if (param->val64) {
> + dev_dbg(&cfg->csdev->dev,
> + "set param %s (%lld)", name, val);
> + param->reg->value.val64 = val;
> + } else {
> + param->reg->value.val32 = (u32)val;
> + dev_dbg(&cfg->csdev->dev,
> + "set param %s (%d)", name, (u32)val);
> + }
> + if (val_idx >= max_idx)
> + break;
> + }
> +
> + /* don't overrun the preset array line */
> + if (val_idx >= max_idx)
> + break;
> + }
> + return 0;
> +}
> +
> +/*
> + * if we are not using a preset, then need to update the feature params
> + * with current values.
> + */
> +static int cscfg_update_curr_params(struct cscfg_config_csdev *cfg)
> +{
> + int i, j;
> + struct cscfg_feature_csdev *feat;
> + struct cscfg_parameter_csdev *param;
> + const char *name;
> + u64 val;
> +
> + for (i = 0; i < cfg->nr_feat; i++) {
> + feat = cfg->feats[i];
> + if (!feat->nr_params)
> + continue;
> + for (j = 0; j < feat->nr_params; j++) {
> + param = &feat->params[j];
> + name = feat->desc->params[j].name;
> + val = param->current_value;
> + if (param->val64) {
> + dev_dbg(&cfg->csdev->dev,
> + "set param %s (%lld)", name, val);
> + param->reg->value.val64 = val;
> + } else {
> + param->reg->value.val32 = (u32)val;
> + dev_dbg(&cfg->csdev->dev,
> + "set param %s (%d)", name, (u32)val);
> + }
> + }
> + }
> + return 0;
> +}
> +
> +static int cscfg_prog_config(struct cscfg_config_csdev *cfg, bool enable)
> +{
> + int i, err = 0;
> + struct cscfg_feature_csdev *feat;
> + struct coresight_device *csdev;
> +
> + for (i = 0; i < cfg->nr_feat; i++) {
> + feat = cfg->feats[i];
> + csdev = feat->csdev;
> + dev_dbg(&csdev->dev, "cfg %s; %s feature:%s", cfg->desc->name,
> + enable ? "enable" : "disable", feat->desc->name);
> +
> + if (enable)
> + err = cscfg_set_on_enable(feat);
> + else
> + cscfg_save_on_disable(feat);
> +
> + if (err)
> + break;
> + }
> + return err;
> +}
> +
> +/**
> + * Enable configuration for the device.
> + *
> + * @cfg: config_csdev to set.
> + * @preset: preset values to use - 0 for default.
> + */
> +int cscfg_csdev_enable_config(struct cscfg_config_csdev *cfg, int preset)
> +{
> + int err = 0;
> +
> + if (preset)
> + err = cscfg_update_presets(cfg, preset);
> + else
> + err = cscfg_update_curr_params(cfg);
> + if (!err)
> + err = cscfg_prog_config(cfg, true);
> + if (!err)
> + cfg->enabled = true;
> + return err;
> +}
> +
> +void cscfg_csdev_disable_config(struct cscfg_config_csdev *cfg)
> +{
> + if (cfg->enabled) {
> + cscfg_prog_config(cfg, false);
> + cfg->enabled = false;
> + }
> +}
> diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
> index 75ecdecf7013..9d66e0071f38 100644
> --- a/drivers/hwtracing/coresight/coresight-config.h
> +++ b/drivers/hwtracing/coresight/coresight-config.h
> @@ -53,7 +53,10 @@ struct cscfg_parameter_desc {
> };
>
> /**
> - * Representation of register value.
> + * Representation of register value and a descriptor of register usage.
> + *
> + * Used as a descriptor in the feature descriptors.
> + * Used as a value in when in a feature loading into a csdev.

Please move this to patch 01.

> *
> * Supports full 64 bit register value, or 32 bit value with optional mask
> * value.
> @@ -262,4 +265,13 @@ struct cscfg_csdev_feat_ops {
> struct cscfg_feature_csdev *feat);
> };
>
> +/* coresight config helper functions*/
> +
> +/* enable / disable config on a device - called with appropriate locks set.*/
> +int cscfg_csdev_enable_config(struct cscfg_config_csdev *cfg, int preset);
> +void cscfg_csdev_disable_config(struct cscfg_config_csdev *cfg);
> +
> +/* reset a feature to default values */
> +void cscfg_reset_feat(struct cscfg_feature_csdev *feat);
> +
> #endif /* _CORESIGHT_CORESIGHT_CONFIG_H */
> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> index c04cea0c1db2..4b8e4e35e3e7 100644
> --- a/drivers/hwtracing/coresight/coresight-syscfg.c
> +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
> @@ -198,14 +198,15 @@ static int cscfg_load_feat_csdev(struct coresight_device *csdev,
> if (!feat_csdev)
> return -ENOMEM;
>
> - /* load the feature into the device - may modify default ops*/
> + /* load the feature into the device */

The right comment should be added in patch 02 and not changed without code to
sustain it.

A rigorous and consistent naming convention is of prime importance in this
patch. Otherwise I think it is holding together well.

More comments tomorrow.

Thanks,
Mathieu

> err = ops->load_feat(csdev, feat_csdev);
> if (err)
> return err;
>
> - /* add to internal csdev feature list */
> + /* add to internal csdev feature list & initialise using reset call */
> mutex_lock(&cscfg_csdev_mutex);
> list_add(&feat_csdev->node, &csdev->feature_csdev_list);
> + cscfg_reset_feat(feat_csdev);
> mutex_unlock(&cscfg_csdev_mutex);
>
> return 0;
> --
> 2.17.1
>
>
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> linux-arm-kernel mailing list
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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