coresight: syscfg: Add initial configfs support

Adds configfs subsystem and attributes to the configuration manager
to enable the listing of loaded configurations and features.

The default values of feature parameters can be accessed and altered
from these attributes to affect all installed devices using the feature.

Link: https://lore.kernel.org/r/20210723165444.1048-10-mike.leach@linaro.org
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210818194022.379573-10-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 396 insertions, 0 deletions

diff --git a/drivers/hwtracing/coresight/coresight-syscfg-configfs.c b/drivers/hwtracing/coresight/coresight-syscfg-configfs.c
new file mode 100644
index 000000000000..c547816b9000
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-syscfg-configfs.c
@@ -0,0 +1,396 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020 Linaro Limited, All rights reserved.
+ * Author: Mike Leach <mike.leach@linaro.org>
+ */
+
+#include <linux/configfs.h>
+
+#include "coresight-syscfg-configfs.h"
+
+/* create a default ci_type. */
+static inline struct config_item_type *cscfg_create_ci_type(void)
+{
+	struct config_item_type *ci_type;
+
+	ci_type = devm_kzalloc(cscfg_device(), sizeof(*ci_type), GFP_KERNEL);
+	if (ci_type)
+		ci_type->ct_owner = THIS_MODULE;
+
+	return ci_type;
+}
+
+/* configurations sub-group */
+
+/* attributes for the config view group */
+static ssize_t cscfg_cfg_description_show(struct config_item *item, char *page)
+{
+	struct cscfg_fs_config *fs_config = container_of(to_config_group(item),
+							 struct cscfg_fs_config, group);
+
+	return scnprintf(page, PAGE_SIZE, "%s", fs_config->config_desc->description);
+}
+CONFIGFS_ATTR_RO(cscfg_cfg_, description);
+
+static ssize_t cscfg_cfg_feature_refs_show(struct config_item *item, char *page)
+{
+	struct cscfg_fs_config *fs_config = container_of(to_config_group(item),
+							 struct cscfg_fs_config, group);
+	const struct cscfg_config_desc *config_desc = fs_config->config_desc;
+	ssize_t ch_used = 0;
+	int i;
+
+	for (i = 0; i < config_desc->nr_feat_refs; i++)
+		ch_used += scnprintf(page + ch_used, PAGE_SIZE - ch_used,
+				     "%s\n", config_desc->feat_ref_names[i]);
+	return ch_used;
+}
+CONFIGFS_ATTR_RO(cscfg_cfg_, feature_refs);
+
+/* list preset values in order of features and params */
+static ssize_t cscfg_cfg_values_show(struct config_item *item, char *page)
+{
+	const struct cscfg_feature_desc *feat_desc;
+	const struct cscfg_config_desc *config_desc;
+	struct cscfg_fs_preset *fs_preset;
+	int i, j, val_idx, preset_idx;
+	ssize_t used = 0;
+
+	fs_preset = container_of(to_config_group(item), struct cscfg_fs_preset, group);
+	config_desc = fs_preset->config_desc;
+
+	if (!config_desc->nr_presets)
+		return 0;
+
+	preset_idx = fs_preset->preset_num - 1;
+
+	/* start index on the correct array line */
+	val_idx = config_desc->nr_total_params * preset_idx;
+
+	/*
+	 * A set of presets is the sum of all params in used features,
+	 * in order of declaration of features and params in the features
+	 */
+	for (i = 0; i < config_desc->nr_feat_refs; i++) {
+		feat_desc = cscfg_get_named_feat_desc(config_desc->feat_ref_names[i]);
+		for (j = 0; j < feat_desc->nr_params; j++) {
+			used += scnprintf(page + used, PAGE_SIZE - used,
+					  "%s.%s = 0x%llx ",
+					  feat_desc->name,
+					  feat_desc->params_desc[j].name,
+					  config_desc->presets[val_idx++]);
+		}
+	}
+	used += scnprintf(page + used, PAGE_SIZE - used, "\n");
+
+	return used;
+}
+CONFIGFS_ATTR_RO(cscfg_cfg_, values);
+
+static struct configfs_attribute *cscfg_config_view_attrs[] = {
+	&cscfg_cfg_attr_description,
+	&cscfg_cfg_attr_feature_refs,
+	NULL,
+};
+
+static struct config_item_type cscfg_config_view_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_attrs = cscfg_config_view_attrs,
+};
+
+static struct configfs_attribute *cscfg_config_preset_attrs[] = {
+	&cscfg_cfg_attr_values,
+	NULL,
+};
+
+static struct config_item_type cscfg_config_preset_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_attrs = cscfg_config_preset_attrs,
+};
+
+static int cscfg_add_preset_groups(struct cscfg_fs_config *cfg_view)
+{
+	int preset_num;
+	struct cscfg_fs_preset *cfg_fs_preset;
+	struct cscfg_config_desc *config_desc = cfg_view->config_desc;
+	char name[CONFIGFS_ITEM_NAME_LEN];
+
+	if (!config_desc->nr_presets)
+		return 0;
+
+	for (preset_num = 1; preset_num <= config_desc->nr_presets; preset_num++) {
+		cfg_fs_preset = devm_kzalloc(cscfg_device(),
+					     sizeof(struct cscfg_fs_preset), GFP_KERNEL);
+
+		if (!cfg_fs_preset)
+			return -ENOMEM;
+
+		snprintf(name, CONFIGFS_ITEM_NAME_LEN, "preset%d", preset_num);
+		cfg_fs_preset->preset_num = preset_num;
+		cfg_fs_preset->config_desc = cfg_view->config_desc;
+		config_group_init_type_name(&cfg_fs_preset->group, name,
+					    &cscfg_config_preset_type);
+		configfs_add_default_group(&cfg_fs_preset->group, &cfg_view->group);
+	}
+	return 0;
+}
+
+static struct config_group *cscfg_create_config_group(struct cscfg_config_desc *config_desc)
+{
+	struct cscfg_fs_config *cfg_view;
+	struct device *dev = cscfg_device();
+	int err;
+
+	if (!dev)
+		return ERR_PTR(-EINVAL);
+
+	cfg_view = devm_kzalloc(dev, sizeof(struct cscfg_fs_config), GFP_KERNEL);
+	if (!cfg_view)
+		return ERR_PTR(-ENOMEM);
+
+	cfg_view->config_desc = config_desc;
+	config_group_init_type_name(&cfg_view->group, config_desc->name, &cscfg_config_view_type);
+
+	/* add in a preset<n> dir for each preset */
+	err = cscfg_add_preset_groups(cfg_view);
+	if (err)
+		return ERR_PTR(err);
+
+	return &cfg_view->group;
+}
+
+/* attributes for features view */
+
+static ssize_t cscfg_feat_description_show(struct config_item *item, char *page)
+{
+	struct cscfg_fs_feature *fs_feat = container_of(to_config_group(item),
+							struct cscfg_fs_feature, group);
+
+	return scnprintf(page, PAGE_SIZE, "%s", fs_feat->feat_desc->description);
+}
+CONFIGFS_ATTR_RO(cscfg_feat_, description);
+
+static ssize_t cscfg_feat_matches_show(struct config_item *item, char *page)
+{
+	struct cscfg_fs_feature *fs_feat = container_of(to_config_group(item),
+							struct cscfg_fs_feature, group);
+	u32 match_flags = fs_feat->feat_desc->match_flags;
+	int used = 0;
+
+	if (match_flags & CS_CFG_MATCH_CLASS_SRC_ALL)
+		used = scnprintf(page, PAGE_SIZE, "SRC_ALL ");
+
+	if (match_flags & CS_CFG_MATCH_CLASS_SRC_ETM4)
+		used += scnprintf(page + used, PAGE_SIZE - used, "SRC_ETMV4 ");
+
+	used += scnprintf(page + used, PAGE_SIZE - used, "\n");
+	return used;
+}
+CONFIGFS_ATTR_RO(cscfg_feat_, matches);
+
+static ssize_t cscfg_feat_nr_params_show(struct config_item *item, char *page)
+{
+	struct cscfg_fs_feature *fs_feat = container_of(to_config_group(item),
+							struct cscfg_fs_feature, group);
+
+	return scnprintf(page, PAGE_SIZE, "%d\n", fs_feat->feat_desc->nr_params);
+}
+CONFIGFS_ATTR_RO(cscfg_feat_, nr_params);
+
+/* base feature desc attrib structures */
+static struct configfs_attribute *cscfg_feature_view_attrs[] = {
+	&cscfg_feat_attr_description,
+	&cscfg_feat_attr_matches,
+	&cscfg_feat_attr_nr_params,
+	NULL,
+};
+
+static struct config_item_type cscfg_feature_view_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_attrs = cscfg_feature_view_attrs,
+};
+
+static ssize_t cscfg_param_value_show(struct config_item *item, char *page)
+{
+	struct cscfg_fs_param *param_item = container_of(to_config_group(item),
+							 struct cscfg_fs_param, group);
+	u64 value = param_item->feat_desc->params_desc[param_item->param_idx].value;
+
+	return scnprintf(page, PAGE_SIZE, "0x%llx\n", value);
+}
+
+static ssize_t cscfg_param_value_store(struct config_item *item,
+				       const char *page, size_t size)
+{
+	struct cscfg_fs_param *param_item = container_of(to_config_group(item),
+							 struct cscfg_fs_param, group);
+	struct cscfg_feature_desc *feat_desc = param_item->feat_desc;
+	int param_idx = param_item->param_idx;
+	u64 value;
+	int err;
+
+	err = kstrtoull(page, 0, &value);
+	if (!err)
+		err = cscfg_update_feat_param_val(feat_desc, param_idx, value);
+
+	return err ? err : size;
+}
+CONFIGFS_ATTR(cscfg_param_, value);
+
+static struct configfs_attribute *cscfg_param_view_attrs[] = {
+	&cscfg_param_attr_value,
+	NULL,
+};
+
+static struct config_item_type cscfg_param_view_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_attrs = cscfg_param_view_attrs,
+};
+
+/*
+ * configfs has far less functionality provided to add attributes dynamically than sysfs,
+ * and the show and store fns pass the enclosing config_item so the actual attribute cannot
+ * be determined. Therefore we add each item as a group directory, with a value attribute.
+ */
+static int cscfg_create_params_group_items(struct cscfg_feature_desc *feat_desc,
+					   struct config_group *params_group)
+{
+	struct device *dev = cscfg_device();
+	struct cscfg_fs_param *param_item;
+	int i;
+
+	/* parameter items - as groups with default_value attribute */
+	for (i = 0; i < feat_desc->nr_params; i++) {
+		param_item = devm_kzalloc(dev, sizeof(struct cscfg_fs_param), GFP_KERNEL);
+		if (!param_item)
+			return -ENOMEM;
+		param_item->feat_desc = feat_desc;
+		param_item->param_idx = i;
+		config_group_init_type_name(&param_item->group,
+					    feat_desc->params_desc[i].name,
+					    &cscfg_param_view_type);
+		configfs_add_default_group(&param_item->group, params_group);
+	}
+	return 0;
+}
+
+static struct config_group *cscfg_create_feature_group(struct cscfg_feature_desc *feat_desc)
+{
+	struct cscfg_fs_feature *feat_view;
+	struct config_item_type *params_group_type;
+	struct config_group *params_group = NULL;
+	struct device *dev = cscfg_device();
+	int item_err;
+
+	if (!dev)
+		return ERR_PTR(-EINVAL);
+
+	feat_view = devm_kzalloc(dev, sizeof(struct cscfg_fs_feature), GFP_KERNEL);
+	if (!feat_view)
+		return ERR_PTR(-ENOMEM);
+
+	if (feat_desc->nr_params) {
+		params_group = devm_kzalloc(dev, sizeof(struct config_group), GFP_KERNEL);
+		if (!params_group)
+			return ERR_PTR(-ENOMEM);
+
+		params_group_type = cscfg_create_ci_type();
+		if (!params_group_type)
+			return ERR_PTR(-ENOMEM);
+	}
+
+	feat_view->feat_desc = feat_desc;
+	config_group_init_type_name(&feat_view->group,
+				    feat_desc->name,
+				    &cscfg_feature_view_type);
+	if (params_group) {
+		config_group_init_type_name(params_group, "params", params_group_type);
+		configfs_add_default_group(params_group, &feat_view->group);
+		item_err = cscfg_create_params_group_items(feat_desc, params_group);
+		if (item_err)
+			return ERR_PTR(item_err);
+	}
+	return &feat_view->group;
+}
+
+static struct config_item_type cscfg_configs_type = {
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_group cscfg_configs_grp = {
+	.cg_item = {
+		.ci_namebuf = "configurations",
+		.ci_type = &cscfg_configs_type,
+	},
+};
+
+/* add configuration to configurations group */
+int cscfg_configfs_add_config(struct cscfg_config_desc *config_desc)
+{
+	struct config_group *new_group;
+	int err;
+
+	new_group = cscfg_create_config_group(config_desc);
+	if (IS_ERR(new_group))
+		return PTR_ERR(new_group);
+	err =  configfs_register_group(&cscfg_configs_grp, new_group);
+	return err;
+}
+
+static struct config_item_type cscfg_features_type = {
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_group cscfg_features_grp = {
+	.cg_item = {
+		.ci_namebuf = "features",
+		.ci_type = &cscfg_features_type,
+	},
+};
+
+/* add feature to features group */
+int cscfg_configfs_add_feature(struct cscfg_feature_desc *feat_desc)
+{
+	struct config_group *new_group;
+	int err;
+
+	new_group = cscfg_create_feature_group(feat_desc);
+	if (IS_ERR(new_group))
+		return PTR_ERR(new_group);
+	err =  configfs_register_group(&cscfg_features_grp, new_group);
+	return err;
+}
+
+int cscfg_configfs_init(struct cscfg_manager *cscfg_mgr)
+{
+	struct configfs_subsystem *subsys;
+	struct config_item_type *ci_type;
+
+	if (!cscfg_mgr)
+		return -EINVAL;
+
+	ci_type = cscfg_create_ci_type();
+	if (!ci_type)
+		return -ENOMEM;
+
+	subsys = &cscfg_mgr->cfgfs_subsys;
+	config_item_set_name(&subsys->su_group.cg_item, CSCFG_FS_SUBSYS_NAME);
+	subsys->su_group.cg_item.ci_type = ci_type;
+
+	config_group_init(&subsys->su_group);
+	mutex_init(&subsys->su_mutex);
+
+	/* Add default groups to subsystem */
+	config_group_init(&cscfg_configs_grp);
+	configfs_add_default_group(&cscfg_configs_grp, &subsys->su_group);
+
+	config_group_init(&cscfg_features_grp);
+	configfs_add_default_group(&cscfg_features_grp, &subsys->su_group);
+
+	return configfs_register_subsystem(subsys);
+}
+
+void cscfg_configfs_release(struct cscfg_manager *cscfg_mgr)
+{
+	configfs_unregister_subsystem(&cscfg_mgr->cfgfs_subsys);
+}