// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2020 Linaro Limited, All rights reserved.
 * Author: Mike Leach <mike.leach@linaro.org>
 */

#include <linux/platform_device.h>
#include <linux/slab.h>

#include "coresight-config.h"
#include "coresight-etm-perf.h"
#include "coresight-syscfg.h"
#include "coresight-syscfg-configfs.h"

/*
 * cscfg_ API manages configurations and features for the entire coresight
 * infrastructure.
 *
 * It allows the loading of configurations and features, and loads these into
 * coresight devices as appropriate.
 */

/* protect the cscsg_data and device */
static DEFINE_MUTEX(cscfg_mutex);

/* only one of these */
static struct cscfg_manager *cscfg_mgr;

/* load features and configuations into the lists */

/* get name feature instance from a coresight device list of features */
static struct cscfg_feature_csdev *
cscfg_get_feat_csdev(struct coresight_device *csdev, const char *name)
{
        struct cscfg_feature_csdev *feat_csdev = NULL;

        list_for_each_entry(feat_csdev, &csdev->feature_csdev_list, node) {
                if (strcmp(feat_csdev->feat_desc->name, name) == 0)
                        return feat_csdev;
        }
        return NULL;
}

/* allocate the device config instance - with max number of used features */
static struct cscfg_config_csdev *
cscfg_alloc_csdev_cfg(struct coresight_device *csdev, int nr_feats)
{
        struct cscfg_config_csdev *config_csdev = NULL;
        struct device *dev = csdev->dev.parent;

        /* this is being allocated using the devm for the coresight device */
        config_csdev = devm_kzalloc(dev,
                                    offsetof(struct cscfg_config_csdev, feats_csdev[nr_feats]),
                                    GFP_KERNEL);
        if (!config_csdev)
                return NULL;

        config_csdev->csdev = csdev;
        return config_csdev;
}

/* Load a config into a device if there are any feature matches between config and device */
static int cscfg_add_csdev_cfg(struct coresight_device *csdev,
                               struct cscfg_config_desc *config_desc)
{
        struct cscfg_config_csdev *config_csdev = NULL;
        struct cscfg_feature_csdev *feat_csdev;
        unsigned long flags;
        int i;

        /* look at each required feature and see if it matches any feature on the device */
        for (i = 0; i < config_desc->nr_feat_refs; i++) {
                /* look for a matching name */
                feat_csdev = cscfg_get_feat_csdev(csdev, config_desc->feat_ref_names[i]);
                if (feat_csdev) {
                        /*
                         * At least one feature on this device matches the config
                         * add a config instance to the device and a reference to the feature.
                         */
                        if (!config_csdev) {
                                config_csdev = cscfg_alloc_csdev_cfg(csdev,
                                                                     config_desc->nr_feat_refs);
                                if (!config_csdev)
                                        return -ENOMEM;
                                config_csdev->config_desc = config_desc;
                        }
                        config_csdev->feats_csdev[config_csdev->nr_feat++] = feat_csdev;
                }
        }
        /* if matched features, add config to device.*/
        if (config_csdev) {
                raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
                list_add(&config_csdev->node, &csdev->config_csdev_list);
                raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
        }

        return 0;
}

/*
 * Add the config to the set of registered devices - call with mutex locked.
 * Iterates through devices - any device that matches one or more of the
 * configuration features will load it, the others will ignore it.
 */
static int cscfg_add_cfg_to_csdevs(struct cscfg_config_desc *config_desc)
{
        struct cscfg_registered_csdev *csdev_item;
        int err;

        list_for_each_entry(csdev_item, &cscfg_mgr->csdev_desc_list, item) {
                err = cscfg_add_csdev_cfg(csdev_item->csdev, config_desc);
                if (err)
                        return err;
        }
        return 0;
}

/*
 * Allocate a feature object for load into a csdev.
 * memory allocated using the csdev->dev object using devm managed allocator.
 */
static struct cscfg_feature_csdev *
cscfg_alloc_csdev_feat(struct coresight_device *csdev, struct cscfg_feature_desc *feat_desc)
{
        struct cscfg_feature_csdev *feat_csdev = NULL;
        struct device *dev = csdev->dev.parent;
        int i;

        feat_csdev = devm_kzalloc(dev, sizeof(struct cscfg_feature_csdev), GFP_KERNEL);
        if (!feat_csdev)
                return NULL;

        /* parameters are optional - could be 0 */
        feat_csdev->nr_params = feat_desc->nr_params;

        /*
         * if we need parameters, zero alloc the space here, the load routine in
         * the csdev device driver will fill out some information according to
         * feature descriptor.
         */
        if (feat_csdev->nr_params) {
                feat_csdev->params_csdev = devm_kcalloc(dev, feat_csdev->nr_params,
                                                        sizeof(struct cscfg_parameter_csdev),
                                                        GFP_KERNEL);
                if (!feat_csdev->params_csdev)
                        return NULL;

                /*
                 * fill in the feature reference in the param - other fields
                 * handled by loader in csdev.
                 */
                for (i = 0; i < feat_csdev->nr_params; i++)
                        feat_csdev->params_csdev[i].feat_csdev = feat_csdev;
        }

        /*
         * Always have registers to program - again the load routine in csdev device
         * will fill out according to feature descriptor and device requirements.
         */
        feat_csdev->nr_regs = feat_desc->nr_regs;
        feat_csdev->regs_csdev = devm_kcalloc(dev, feat_csdev->nr_regs,
                                              sizeof(struct cscfg_regval_csdev),
                                              GFP_KERNEL);
        if (!feat_csdev->regs_csdev)
                return NULL;

        /* load the feature default values */
        feat_csdev->feat_desc = feat_desc;
        feat_csdev->csdev = csdev;

        return feat_csdev;
}

/* load one feature into one coresight device */
static int cscfg_load_feat_csdev(struct coresight_device *csdev,
                                 struct cscfg_feature_desc *feat_desc,
                                 struct cscfg_csdev_feat_ops *ops)
{
        struct cscfg_feature_csdev *feat_csdev;
        unsigned long flags;
        int err;

        if (!ops->load_feat)
                return -EINVAL;

        feat_csdev = cscfg_alloc_csdev_feat(csdev, feat_desc);
        if (!feat_csdev)
                return -ENOMEM;

        /* load the feature into the device */
        err = ops->load_feat(csdev, feat_csdev);
        if (err)
                return err;

        /* add to internal csdev feature list & initialise using reset call */
        cscfg_reset_feat(feat_csdev);
        raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
        list_add(&feat_csdev->node, &csdev->feature_csdev_list);
        raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);

        return 0;
}

/*
 * Add feature to any matching devices - call with mutex locked.
 * Iterates through devices - any device that matches the feature will be
 * called to load it.
 */
static int cscfg_add_feat_to_csdevs(struct cscfg_feature_desc *feat_desc)
{
        struct cscfg_registered_csdev *csdev_item;
        int err;

        list_for_each_entry(csdev_item, &cscfg_mgr->csdev_desc_list, item) {
                if (csdev_item->match_flags & feat_desc->match_flags) {
                        err = cscfg_load_feat_csdev(csdev_item->csdev, feat_desc, &csdev_item->ops);
                        if (err)
                                return err;
                }
        }
        return 0;
}

/* check feature list for a named feature - call with mutex locked. */
static bool cscfg_match_list_feat(const char *name)
{
        struct cscfg_feature_desc *feat_desc;

        list_for_each_entry(feat_desc, &cscfg_mgr->feat_desc_list, item) {
                if (strcmp(feat_desc->name, name) == 0)
                        return true;
        }
        return false;
}

/* check all feat needed for cfg are in the list - call with mutex locked. */
static int cscfg_check_feat_for_cfg(struct cscfg_config_desc *config_desc)
{
        int i;

        for (i = 0; i < config_desc->nr_feat_refs; i++)
                if (!cscfg_match_list_feat(config_desc->feat_ref_names[i]))
                        return -EINVAL;
        return 0;
}

/*
 * load feature - add to feature list.
 */
static int cscfg_load_feat(struct cscfg_feature_desc *feat_desc)
{
        int err;
        struct cscfg_feature_desc *feat_desc_exist;

        /* new feature must have unique name */
        list_for_each_entry(feat_desc_exist, &cscfg_mgr->feat_desc_list, item) {
                if (!strcmp(feat_desc_exist->name, feat_desc->name))
                        return -EEXIST;
        }

        /* add feature to any matching registered devices */
        err = cscfg_add_feat_to_csdevs(feat_desc);
        if (err)
                return err;

        list_add(&feat_desc->item, &cscfg_mgr->feat_desc_list);
        return 0;
}

/*
 * load config into the system - validate used features exist then add to
 * config list.
 */
static int cscfg_load_config(struct cscfg_config_desc *config_desc)
{
        int err;
        struct cscfg_config_desc *config_desc_exist;

        /* new configuration must have a unique name */
        list_for_each_entry(config_desc_exist, &cscfg_mgr->config_desc_list, item) {
                if (!strcmp(config_desc_exist->name, config_desc->name))
                        return -EEXIST;
        }

        /* validate features are present */
        err = cscfg_check_feat_for_cfg(config_desc);
        if (err)
                return err;

        /* add config to any matching registered device */
        err = cscfg_add_cfg_to_csdevs(config_desc);
        if (err)
                return err;

        /* add config to perf fs to allow selection */
        err = etm_perf_add_symlink_cscfg(cscfg_device(), config_desc);
        if (err)
                return err;

        list_add(&config_desc->item, &cscfg_mgr->config_desc_list);
        atomic_set(&config_desc->active_cnt, 0);
        return 0;
}

/* get a feature descriptor by name */
const struct cscfg_feature_desc *cscfg_get_named_feat_desc(const char *name)
{
        const struct cscfg_feature_desc *feat_desc = NULL, *feat_desc_item;

        mutex_lock(&cscfg_mutex);

        list_for_each_entry(feat_desc_item, &cscfg_mgr->feat_desc_list, item) {
                if (strcmp(feat_desc_item->name, name) == 0) {
                        feat_desc = feat_desc_item;
                        break;
                }
        }

        mutex_unlock(&cscfg_mutex);
        return feat_desc;
}

/* called with cscfg_mutex held */
static struct cscfg_feature_csdev *
cscfg_csdev_get_feat_from_desc(struct coresight_device *csdev,
                               struct cscfg_feature_desc *feat_desc)
{
        struct cscfg_feature_csdev *feat_csdev;

        list_for_each_entry(feat_csdev, &csdev->feature_csdev_list, node) {
                if (feat_csdev->feat_desc == feat_desc)
                        return feat_csdev;
        }
        return NULL;
}

int cscfg_update_feat_param_val(struct cscfg_feature_desc *feat_desc,
                                int param_idx, u64 value)
{
        int err = 0;
        struct cscfg_feature_csdev *feat_csdev;
        struct cscfg_registered_csdev *csdev_item;

        mutex_lock(&cscfg_mutex);

        /* check if any config active & return busy */
        if (atomic_read(&cscfg_mgr->sys_active_cnt)) {
                err = -EBUSY;
                goto unlock_exit;
        }

        /* set the value */
        if ((param_idx < 0) || (param_idx >= feat_desc->nr_params)) {
                err = -EINVAL;
                goto unlock_exit;
        }
        feat_desc->params_desc[param_idx].value = value;

        /* update loaded instances.*/
        list_for_each_entry(csdev_item, &cscfg_mgr->csdev_desc_list, item) {
                feat_csdev = cscfg_csdev_get_feat_from_desc(csdev_item->csdev, feat_desc);
                if (feat_csdev)
                        feat_csdev->params_csdev[param_idx].current_value = value;
        }

unlock_exit:
        mutex_unlock(&cscfg_mutex);
        return err;
}

/*
 * Conditionally up reference count on owner to prevent unload.
 *
 * module loaded configs need to be locked in to prevent premature unload.
 */
static int cscfg_owner_get(struct cscfg_load_owner_info *owner_info)
{
        if ((owner_info->type == CSCFG_OWNER_MODULE) &&
            (!try_module_get(owner_info->owner_handle)))
                return -EINVAL;
        return 0;
}

/* conditionally lower ref count on an owner */
static void cscfg_owner_put(struct cscfg_load_owner_info *owner_info)
{
        if (owner_info->type == CSCFG_OWNER_MODULE)
                module_put(owner_info->owner_handle);
}

static void cscfg_remove_owned_csdev_configs(struct coresight_device *csdev, void *load_owner)
{
        struct cscfg_config_csdev *config_csdev, *tmp;

        if (list_empty(&csdev->config_csdev_list))
                return;

        guard(raw_spinlock_irqsave)(&csdev->cscfg_csdev_lock);

        list_for_each_entry_safe(config_csdev, tmp, &csdev->config_csdev_list, node) {
                if (config_csdev->config_desc->load_owner == load_owner)
                        list_del(&config_csdev->node);
        }
}

static void cscfg_remove_owned_csdev_features(struct coresight_device *csdev, void *load_owner)
{
        struct cscfg_feature_csdev *feat_csdev, *tmp;

        if (list_empty(&csdev->feature_csdev_list))
                return;

        list_for_each_entry_safe(feat_csdev, tmp, &csdev->feature_csdev_list, node) {
                if (feat_csdev->feat_desc->load_owner == load_owner)
                        list_del(&feat_csdev->node);
        }
}

/*
 * Unregister all configuration and features from configfs owned by load_owner.
 * Although this is called without the list mutex being held, it is in the
 * context of an unload operation which are strictly serialised,
 * so the lists cannot change during this call.
 */
static void cscfg_fs_unregister_cfgs_feats(void *load_owner)
{
        struct cscfg_config_desc *config_desc;
        struct cscfg_feature_desc *feat_desc;

        list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
                if (config_desc->load_owner == load_owner)
                        cscfg_configfs_del_config(config_desc);
        }
        list_for_each_entry(feat_desc, &cscfg_mgr->feat_desc_list, item) {
                if (feat_desc->load_owner == load_owner)
                        cscfg_configfs_del_feature(feat_desc);
        }
}

/*
 * removal is relatively easy - just remove from all lists, anything that
 * matches the owner. Memory for the descriptors will be managed by the owner,
 * memory for the csdev items is devm_ allocated with the individual csdev
 * devices.
 */
static void cscfg_unload_owned_cfgs_feats(void *load_owner)
{
        struct cscfg_config_desc *config_desc, *cfg_tmp;
        struct cscfg_feature_desc *feat_desc, *feat_tmp;
        struct cscfg_registered_csdev *csdev_item;

        lockdep_assert_held(&cscfg_mutex);

        /* remove from each csdev instance feature and config lists */
        list_for_each_entry(csdev_item, &cscfg_mgr->csdev_desc_list, item) {
                /*
                 * for each csdev, check the loaded lists and remove if
                 * referenced descriptor is owned
                 */
                cscfg_remove_owned_csdev_configs(csdev_item->csdev, load_owner);
                cscfg_remove_owned_csdev_features(csdev_item->csdev, load_owner);
        }

        /* remove from the config descriptor lists */
        list_for_each_entry_safe(config_desc, cfg_tmp, &cscfg_mgr->config_desc_list, item) {
                if (config_desc->load_owner == load_owner) {
                        etm_perf_del_symlink_cscfg(config_desc);
                        list_del(&config_desc->item);
                }
        }

        /* remove from the feature descriptor lists */
        list_for_each_entry_safe(feat_desc, feat_tmp, &cscfg_mgr->feat_desc_list, item) {
                if (feat_desc->load_owner == load_owner) {
                        list_del(&feat_desc->item);
                }
        }
}

/*
 * load the features and configs to the lists - called with list mutex held
 */
static int cscfg_load_owned_cfgs_feats(struct cscfg_config_desc **config_descs,
                                       struct cscfg_feature_desc **feat_descs,
                                       struct cscfg_load_owner_info *owner_info)
{
        int i, err;

        lockdep_assert_held(&cscfg_mutex);

        /* load features first */
        if (feat_descs) {
                for (i = 0; feat_descs[i]; i++) {
                        err = cscfg_load_feat(feat_descs[i]);
                        if (err) {
                                pr_err("coresight-syscfg: Failed to load feature %s\n",
                                       feat_descs[i]->name);
                                return err;
                        }
                        feat_descs[i]->load_owner = owner_info;
                }
        }

        /* next any configurations to check feature dependencies */
        if (config_descs) {
                for (i = 0; config_descs[i]; i++) {
                        err = cscfg_load_config(config_descs[i]);
                        if (err) {
                                pr_err("coresight-syscfg: Failed to load configuration %s\n",
                                       config_descs[i]->name);
                                return err;
                        }
                        config_descs[i]->load_owner = owner_info;
                        config_descs[i]->available = false;
                }
        }
        return 0;
}

/* set configurations as available to activate at the end of the load process */
static void cscfg_set_configs_available(struct cscfg_config_desc **config_descs)
{
        int i;

        lockdep_assert_held(&cscfg_mutex);

        if (config_descs) {
                for (i = 0; config_descs[i]; i++)
                        config_descs[i]->available = true;
        }
}

/*
 * Create and register each of the configurations and features with configfs.
 * Called without mutex being held.
 */
static int cscfg_fs_register_cfgs_feats(struct cscfg_config_desc **config_descs,
                                        struct cscfg_feature_desc **feat_descs)
{
        int i, err;

        if (feat_descs) {
                for (i = 0; feat_descs[i]; i++) {
                        err = cscfg_configfs_add_feature(feat_descs[i]);
                        if (err)
                                return err;
                }
        }
        if (config_descs) {
                for (i = 0; config_descs[i]; i++) {
                        err = cscfg_configfs_add_config(config_descs[i]);
                        if (err)
                                return err;
                }
        }
        return 0;
}

/**
 * cscfg_load_config_sets - API function to load feature and config sets.
 *
 * Take a 0 terminated array of feature descriptors and/or configuration
 * descriptors and load into the system.
 * Features are loaded first to ensure configuration dependencies can be met.
 *
 * To facilitate dynamic loading and unloading, features and configurations
 * have a "load_owner", to allow later unload by the same owner. An owner may
 * be a loadable module or configuration dynamically created via configfs.
 * As later loaded configurations can use earlier loaded features, creating load
 * dependencies, a load order list is maintained. Unload is strictly in the
 * reverse order to load.
 *
 * @config_descs: 0 terminated array of configuration descriptors.
 * @feat_descs:   0 terminated array of feature descriptors.
 * @owner_info:   Information on the owner of this set.
 */
int cscfg_load_config_sets(struct cscfg_config_desc **config_descs,
                           struct cscfg_feature_desc **feat_descs,
                           struct cscfg_load_owner_info *owner_info)
{
        int err = 0;

        mutex_lock(&cscfg_mutex);
        if (cscfg_mgr->load_state != CSCFG_NONE) {
                mutex_unlock(&cscfg_mutex);
                return -EBUSY;
        }
        cscfg_mgr->load_state = CSCFG_LOAD;

        /* first load and add to the lists */
        err = cscfg_load_owned_cfgs_feats(config_descs, feat_descs, owner_info);
        if (err)
                goto err_clean_load;

        /* add the load owner to the load order list */
        list_add_tail(&owner_info->item, &cscfg_mgr->load_order_list);
        if (!list_is_singular(&cscfg_mgr->load_order_list)) {
                /* lock previous item in load order list */
                err = cscfg_owner_get(list_prev_entry(owner_info, item));
                if (err)
                        goto err_clean_owner_list;
        }

        /*
         * make visible to configfs - configfs manipulation must occur outside
         * the list mutex lock to avoid circular lockdep issues with configfs
         * built in mutexes and semaphores. This is safe as it is not possible
         * to start a new load/unload operation till the current one is done.
         */
        mutex_unlock(&cscfg_mutex);

        /* create the configfs elements */
        err = cscfg_fs_register_cfgs_feats(config_descs, feat_descs);
        mutex_lock(&cscfg_mutex);

        if (err)
                goto err_clean_cfs;

        /* mark any new configs as available for activation */
        cscfg_set_configs_available(config_descs);
        goto exit_unlock;

err_clean_cfs:
        /* cleanup after error registering with configfs */
        cscfg_fs_unregister_cfgs_feats(owner_info);

        if (!list_is_singular(&cscfg_mgr->load_order_list))
                cscfg_owner_put(list_prev_entry(owner_info, item));

err_clean_owner_list:
        list_del(&owner_info->item);

err_clean_load:
        cscfg_unload_owned_cfgs_feats(owner_info);

exit_unlock:
        cscfg_mgr->load_state = CSCFG_NONE;
        mutex_unlock(&cscfg_mutex);
        return err;
}
EXPORT_SYMBOL_GPL(cscfg_load_config_sets);

/**
 * cscfg_unload_config_sets - unload a set of configurations by owner.
 *
 * Dynamic unload of configuration and feature sets is done on the basis of
 * the load owner of that set. Later loaded configurations can depend on
 * features loaded earlier.
 *
 * Therefore, unload is only possible if:-
 * 1) no configurations are active.
 * 2) the set being unloaded was the last to be loaded to maintain dependencies.
 *
 * Once the unload operation commences, we disallow any configuration being
 * made active until it is complete.
 *
 * @owner_info: Information on owner for set being unloaded.
 */
int cscfg_unload_config_sets(struct cscfg_load_owner_info *owner_info)
{
        int err = 0;
        struct cscfg_load_owner_info *load_list_item = NULL;

        mutex_lock(&cscfg_mutex);
        if (cscfg_mgr->load_state != CSCFG_NONE) {
                mutex_unlock(&cscfg_mutex);
                return -EBUSY;
        }

        /* unload op in progress also prevents activation of any config */
        cscfg_mgr->load_state = CSCFG_UNLOAD;

        /* cannot unload if anything is active */
        if (atomic_read(&cscfg_mgr->sys_active_cnt)) {
                err = -EBUSY;
                goto exit_unlock;
        }

        /* cannot unload if not last loaded in load order */
        if (!list_empty(&cscfg_mgr->load_order_list)) {
                load_list_item = list_last_entry(&cscfg_mgr->load_order_list,
                                                 struct cscfg_load_owner_info, item);
                if (load_list_item != owner_info)
                        load_list_item = NULL;
        }

        if (!load_list_item) {
                err = -EINVAL;
                goto exit_unlock;
        }

        /* remove from configfs - again outside the scope of the list mutex */
        mutex_unlock(&cscfg_mutex);
        cscfg_fs_unregister_cfgs_feats(owner_info);
        mutex_lock(&cscfg_mutex);

        /* unload everything from lists belonging to load_owner */
        cscfg_unload_owned_cfgs_feats(owner_info);

        /* remove from load order list */
        if (!list_is_singular(&cscfg_mgr->load_order_list)) {
                /* unlock previous item in load order list */
                cscfg_owner_put(list_prev_entry(owner_info, item));
        }
        list_del(&owner_info->item);

exit_unlock:
        cscfg_mgr->load_state = CSCFG_NONE;
        mutex_unlock(&cscfg_mutex);
        return err;
}
EXPORT_SYMBOL_GPL(cscfg_unload_config_sets);

/* Handle coresight device registration and add configs and features to devices */

/* iterate through config lists and load matching configs to device */
static int cscfg_add_cfgs_csdev(struct coresight_device *csdev)
{
        struct cscfg_config_desc *config_desc;
        int err = 0;

        list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
                err = cscfg_add_csdev_cfg(csdev, config_desc);
                if (err)
                        break;
        }
        return err;
}

/* iterate through feature lists and load matching features to device */
static int cscfg_add_feats_csdev(struct coresight_device *csdev,
                                 u32 match_flags,
                                 struct cscfg_csdev_feat_ops *ops)
{
        struct cscfg_feature_desc *feat_desc;
        int err = 0;

        if (!ops->load_feat)
                return -EINVAL;

        list_for_each_entry(feat_desc, &cscfg_mgr->feat_desc_list, item) {
                if (feat_desc->match_flags & match_flags) {
                        err = cscfg_load_feat_csdev(csdev, feat_desc, ops);
                        if (err)
                                break;
                }
        }
        return err;
}

/* Add coresight device to list and copy its matching info */
static int cscfg_list_add_csdev(struct coresight_device *csdev,
                                u32 match_flags,
                                struct cscfg_csdev_feat_ops *ops)
{
        struct cscfg_registered_csdev *csdev_item;

        /* allocate the list entry structure */
        csdev_item = kzalloc_obj(struct cscfg_registered_csdev);
        if (!csdev_item)
                return -ENOMEM;

        csdev_item->csdev = csdev;
        csdev_item->match_flags = match_flags;
        csdev_item->ops.load_feat = ops->load_feat;
        list_add(&csdev_item->item, &cscfg_mgr->csdev_desc_list);

        INIT_LIST_HEAD(&csdev->feature_csdev_list);
        INIT_LIST_HEAD(&csdev->config_csdev_list);
        raw_spin_lock_init(&csdev->cscfg_csdev_lock);

        return 0;
}

/* remove a coresight device from the list and free data */
static void cscfg_list_remove_csdev(struct coresight_device *csdev)
{
        struct cscfg_registered_csdev *csdev_item, *tmp;

        list_for_each_entry_safe(csdev_item, tmp, &cscfg_mgr->csdev_desc_list, item) {
                if (csdev_item->csdev == csdev) {
                        list_del(&csdev_item->item);
                        kfree(csdev_item);
                        break;
                }
        }
}

/**
 * cscfg_register_csdev - register a coresight device with the syscfg manager.
 *
 * Registers the coresight device with the system. @match_flags used to check
 * if the device is a match for registered features. Any currently registered
 * configurations and features that match the device will be loaded onto it.
 *
 * @csdev:              The coresight device to register.
 * @match_flags:        Matching information to load features.
 * @ops:                Standard operations supported by the device.
 */
int cscfg_register_csdev(struct coresight_device *csdev,
                         u32 match_flags,
                         struct cscfg_csdev_feat_ops *ops)
{
        int ret = 0;

        mutex_lock(&cscfg_mutex);

        /* add device to list of registered devices  */
        ret = cscfg_list_add_csdev(csdev, match_flags, ops);
        if (ret)
                goto reg_csdev_unlock;

        /* now load any registered features and configs matching the device. */
        ret = cscfg_add_feats_csdev(csdev, match_flags, ops);
        if (ret) {
                cscfg_list_remove_csdev(csdev);
                goto reg_csdev_unlock;
        }

        ret = cscfg_add_cfgs_csdev(csdev);
        if (ret) {
                cscfg_list_remove_csdev(csdev);
                goto reg_csdev_unlock;
        }

        pr_info("CSCFG registered %s", dev_name(&csdev->dev));

reg_csdev_unlock:
        mutex_unlock(&cscfg_mutex);
        return ret;
}
EXPORT_SYMBOL_GPL(cscfg_register_csdev);

/**
 * cscfg_unregister_csdev - remove coresight device from syscfg manager.
 *
 * @csdev: Device to remove.
 */
void cscfg_unregister_csdev(struct coresight_device *csdev)
{
        mutex_lock(&cscfg_mutex);
        cscfg_list_remove_csdev(csdev);
        mutex_unlock(&cscfg_mutex);
}
EXPORT_SYMBOL_GPL(cscfg_unregister_csdev);

/**
 * cscfg_csdev_reset_feats - reset features for a CoreSight device.
 *
 * Resets all parameters and register values for any features loaded
 * into @csdev to their default values.
 *
 * @csdev: The CoreSight device.
 */
void cscfg_csdev_reset_feats(struct coresight_device *csdev)
{
        struct cscfg_feature_csdev *feat_csdev;
        unsigned long flags;

        raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
        if (list_empty(&csdev->feature_csdev_list))
                goto unlock_exit;

        list_for_each_entry(feat_csdev, &csdev->feature_csdev_list, node)
                cscfg_reset_feat(feat_csdev);

unlock_exit:
        raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
}
EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats);

static bool cscfg_config_desc_get(struct cscfg_config_desc *config_desc)
{
        if (!atomic_fetch_inc(&config_desc->active_cnt)) {
                /* must ensure that config cannot be unloaded in use */
                if (unlikely(cscfg_owner_get(config_desc->load_owner))) {
                        atomic_dec(&config_desc->active_cnt);
                        return false;
                }
        }

        return true;
}

static void cscfg_config_desc_put(struct cscfg_config_desc *config_desc)
{
        if (!atomic_dec_return(&config_desc->active_cnt))
                cscfg_owner_put(config_desc->load_owner);
}

/*
 * This activate configuration for either perf or sysfs. Perf can have multiple
 * active configs, selected per event, sysfs is limited to one.
 *
 * Increments the configuration descriptor active count and the global active
 * count.
 *
 * @cfg_hash: Hash value of the selected configuration name.
 */
static int _cscfg_activate_config(unsigned long cfg_hash)
{
        struct cscfg_config_desc *config_desc;
        int err = -EINVAL;

        if (cscfg_mgr->load_state == CSCFG_UNLOAD)
                return -EBUSY;

        list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
                if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
                        /* if we happen upon a partly loaded config, can't use it */
                        if (config_desc->available == false)
                                return -EBUSY;

                        if (!cscfg_config_desc_get(config_desc)) {
                                err = -EINVAL;
                                break;
                        }

                        /*
                         * increment the global active count - control changes to
                         * active configurations
                         */
                        atomic_inc(&cscfg_mgr->sys_active_cnt);

                        err = 0;
                        dev_dbg(cscfg_device(), "Activate config %s.\n", config_desc->name);
                        break;
                }
        }
        return err;
}

static void _cscfg_deactivate_config(unsigned long cfg_hash)
{
        struct cscfg_config_desc *config_desc;

        list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
                if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
                        atomic_dec(&cscfg_mgr->sys_active_cnt);
                        cscfg_config_desc_put(config_desc);
                        dev_dbg(cscfg_device(), "Deactivate config %s.\n", config_desc->name);
                        break;
                }
        }
}

/*
 * called from configfs to set/clear the active configuration for use when
 * using sysfs to control trace.
 */
int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool activate)
{
        unsigned long cfg_hash;
        int err = 0;

        mutex_lock(&cscfg_mutex);

        cfg_hash = (unsigned long)config_desc->event_ea->var;

        if (activate) {
                /* cannot be a current active value to activate this */
                if (cscfg_mgr->sysfs_active_config) {
                        err = -EBUSY;
                        goto exit_unlock;
                }
                err = _cscfg_activate_config(cfg_hash);
                if (!err)
                        cscfg_mgr->sysfs_active_config = cfg_hash;
        } else {
                /* disable if matching current value */
                if (cscfg_mgr->sysfs_active_config == cfg_hash) {
                        _cscfg_deactivate_config(cfg_hash);
                        cscfg_mgr->sysfs_active_config = 0;
                } else
                        err = -EINVAL;
        }

exit_unlock:
        mutex_unlock(&cscfg_mutex);
        return err;
}

/* set the sysfs preset value */
void cscfg_config_sysfs_set_preset(int preset)
{
        mutex_lock(&cscfg_mutex);
        cscfg_mgr->sysfs_active_preset = preset;
        mutex_unlock(&cscfg_mutex);
}

/*
 * Used by a device to get the config and preset selected as active in configfs,
 * when using sysfs to control trace.
 */
void cscfg_config_sysfs_get_active_cfg(unsigned long *cfg_hash, int *preset)
{
        mutex_lock(&cscfg_mutex);
        *preset = cscfg_mgr->sysfs_active_preset;
        *cfg_hash = cscfg_mgr->sysfs_active_config;
        mutex_unlock(&cscfg_mutex);
}
EXPORT_SYMBOL_GPL(cscfg_config_sysfs_get_active_cfg);

/**
 * cscfg_activate_config -  Mark a configuration descriptor as active.
 *
 * This will be seen when csdev devices are enabled in the system.
 * Only activated configurations can be enabled on individual devices.
 * Activation protects the configuration from alteration or removal while
 * active.
 *
 * Selection by hash value - generated from the configuration name when it
 * was loaded and added to the cs_etm/configurations file system for selection
 * by perf.
 *
 * @cfg_hash: Hash value of the selected configuration name.
 */
int cscfg_activate_config(unsigned long cfg_hash)
{
        int err = 0;

        mutex_lock(&cscfg_mutex);
        err = _cscfg_activate_config(cfg_hash);
        mutex_unlock(&cscfg_mutex);

        return err;
}
EXPORT_SYMBOL_GPL(cscfg_activate_config);

/**
 * cscfg_deactivate_config -  Mark a config descriptor as inactive.
 *
 * Decrement the configuration and global active counts.
 *
 * @cfg_hash: Hash value of the selected configuration name.
 */
void cscfg_deactivate_config(unsigned long cfg_hash)
{
        mutex_lock(&cscfg_mutex);
        _cscfg_deactivate_config(cfg_hash);
        mutex_unlock(&cscfg_mutex);
}
EXPORT_SYMBOL_GPL(cscfg_deactivate_config);

/**
 * cscfg_csdev_enable_active_config - Enable matching active configuration for device.
 *
 * Enables the configuration selected by @cfg_hash if the configuration is supported
 * on the device and has been activated.
 *
 * If active and supported the CoreSight device @csdev will be programmed with the
 * configuration, using @preset parameters.
 *
 * Should be called before driver hardware enable for the requested device, prior to
 * programming and enabling the physical hardware.
 *
 * @csdev:      CoreSight device to program.
 * @cfg_hash:   Selector for the configuration.
 * @preset:     Preset parameter values to use, 0 for current / default values.
 */
int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
                                     unsigned long cfg_hash, int preset)
{
        struct cscfg_config_csdev *config_csdev_active = NULL, *config_csdev_item;
        struct cscfg_config_desc *config_desc;
        unsigned long flags;
        int err = 0;

        /* quickly check global count */
        if (!atomic_read(&cscfg_mgr->sys_active_cnt))
                return 0;

        /*
         * Look for matching configuration - set the active configuration
         * context if found.
         */
        raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
        list_for_each_entry(config_csdev_item, &csdev->config_csdev_list, node) {
                config_desc = config_csdev_item->config_desc;
                if (((unsigned long)config_desc->event_ea->var == cfg_hash) &&
                                cscfg_config_desc_get(config_desc)) {
                        config_csdev_active = config_csdev_item;
                        csdev->active_cscfg_ctxt = (void *)config_csdev_active;
                        break;
                }
        }
        raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);

        /*
         * If found, attempt to enable
         */
        if (config_csdev_active) {
                /*
                 * Call the generic routine that will program up the internal
                 * driver structures prior to programming up the hardware.
                 * This routine takes the driver spinlock saved in the configs.
                 */
                err = cscfg_csdev_enable_config(config_csdev_active, preset);
                if (!err) {
                        /*
                         * Successful programming. Check the active_cscfg_ctxt
                         * pointer to ensure no pre-emption disabled it via
                         * cscfg_csdev_disable_active_config() before
                         * we could start.
                         *
                         * Set enabled if OK, err if not.
                         */
                        raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
                        if (csdev->active_cscfg_ctxt)
                                config_csdev_active->enabled = true;
                        else
                                err = -EBUSY;
                        raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
                }

                if (err)
                        cscfg_config_desc_put(config_desc);
        }

        return err;
}
EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config);

/**
 * cscfg_csdev_disable_active_config - disable an active config on the device.
 *
 * Disables the active configuration on the CoreSight device @csdev.
 * Disable will save the values of any registers marked in the configurations
 * as save on disable.
 *
 * Should be called after driver hardware disable for the requested device,
 * after disabling the physical hardware and reading back registers.
 *
 * @csdev: The CoreSight device.
 */
void cscfg_csdev_disable_active_config(struct coresight_device *csdev)
{
        struct cscfg_config_csdev *config_csdev;
        unsigned long flags;

        /*
         * Check if we have an active config, and that it was successfully enabled.
         * If it was not enabled, we have no work to do, otherwise mark as disabled.
         * Clear the active config pointer.
         */
        raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
        config_csdev = (struct cscfg_config_csdev *)csdev->active_cscfg_ctxt;
        if (config_csdev) {
                if (!config_csdev->enabled)
                        config_csdev = NULL;
                else
                        config_csdev->enabled = false;
        }
        csdev->active_cscfg_ctxt = NULL;
        raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);

        /* true if there was an enabled active config */
        if (config_csdev) {
                cscfg_csdev_disable_config(config_csdev);
                cscfg_config_desc_put(config_csdev->config_desc);
        }
}
EXPORT_SYMBOL_GPL(cscfg_csdev_disable_active_config);

/* Initialise system configuration management device. */

struct device *cscfg_device(void)
{
        return cscfg_mgr ? &cscfg_mgr->dev : NULL;
}

/* Must have a release function or the kernel will complain on module unload */
static void cscfg_dev_release(struct device *dev)
{
        mutex_lock(&cscfg_mutex);
        kfree(cscfg_mgr);
        cscfg_mgr = NULL;
        mutex_unlock(&cscfg_mutex);
}

/* a device is needed to "own" some kernel elements such as sysfs entries.  */
static int cscfg_create_device(void)
{
        struct device *dev;
        int err = -ENOMEM;

        mutex_lock(&cscfg_mutex);
        if (cscfg_mgr) {
                err = -EINVAL;
                goto create_dev_exit_unlock;
        }

        cscfg_mgr = kzalloc_obj(struct cscfg_manager);
        if (!cscfg_mgr)
                goto create_dev_exit_unlock;

        /* initialise the cscfg_mgr structure */
        INIT_LIST_HEAD(&cscfg_mgr->csdev_desc_list);
        INIT_LIST_HEAD(&cscfg_mgr->feat_desc_list);
        INIT_LIST_HEAD(&cscfg_mgr->config_desc_list);
        INIT_LIST_HEAD(&cscfg_mgr->load_order_list);
        atomic_set(&cscfg_mgr->sys_active_cnt, 0);
        cscfg_mgr->load_state = CSCFG_NONE;

        /* setup the device */
        dev = cscfg_device();
        dev->release = cscfg_dev_release;
        dev->init_name = "cs_system_cfg";

        err = device_register(dev);
        if (err)
                put_device(dev);

create_dev_exit_unlock:
        mutex_unlock(&cscfg_mutex);
        return err;
}

/*
 * Loading and unloading is generally on user discretion.
 * If exiting due to coresight module unload, we need to unload any configurations that remain,
 * before we unregister the configfs intrastructure.
 *
 * Do this by walking the load_owner list and taking appropriate action, depending on the load
 * owner type.
 */
static void cscfg_unload_cfgs_on_exit(void)
{
        struct cscfg_load_owner_info *owner_info = NULL;

        /*
         * grab the mutex - even though we are exiting, some configfs files
         * may still be live till we dump them, so ensure list data is
         * protected from a race condition.
         */
        mutex_lock(&cscfg_mutex);
        while (!list_empty(&cscfg_mgr->load_order_list)) {

                /* remove in reverse order of loading */
                owner_info = list_last_entry(&cscfg_mgr->load_order_list,
                                             struct cscfg_load_owner_info, item);

                /* action according to type */
                switch (owner_info->type) {
                case CSCFG_OWNER_PRELOAD:
                        /*
                         * preloaded  descriptors are statically allocated in
                         * this module - just need to unload dynamic items from
                         * csdev lists, and remove from configfs directories.
                         */
                        pr_info("cscfg: unloading preloaded configurations\n");
                        break;

                case  CSCFG_OWNER_MODULE:
                        /*
                         * this is an error - the loadable module must have been unloaded prior
                         * to the coresight module unload. Therefore that module has not
                         * correctly unloaded configs in its own exit code.
                         * Nothing to do other than emit an error string as the static descriptor
                         * references we need to unload will have disappeared with the module.
                         */
                        pr_err("cscfg: ERROR: prior module failed to unload configuration\n");
                        goto list_remove;
                }

                /* remove from configfs - outside the scope of the list mutex */
                mutex_unlock(&cscfg_mutex);
                cscfg_fs_unregister_cfgs_feats(owner_info);
                mutex_lock(&cscfg_mutex);

                /* Next unload from csdev lists. */
                cscfg_unload_owned_cfgs_feats(owner_info);

list_remove:
                /* remove from load order list */
                list_del(&owner_info->item);
        }
        mutex_unlock(&cscfg_mutex);
}

static void cscfg_clear_device(void)
{
        cscfg_unload_cfgs_on_exit();
        cscfg_configfs_release(cscfg_mgr);
        device_unregister(cscfg_device());
}

/* Initialise system config management API device  */
int __init cscfg_init(void)
{
        int err = 0;

        /* create the device and init cscfg_mgr */
        err = cscfg_create_device();
        if (err)
                return err;

        /* initialise configfs subsystem */
        err = cscfg_configfs_init(cscfg_mgr);
        if (err)
                goto exit_err;

        /* preload built-in configurations */
        err = cscfg_preload(THIS_MODULE);
        if (err)
                goto exit_err;

        dev_info(cscfg_device(), "CoreSight Configuration manager initialised");
        return 0;

exit_err:
        cscfg_clear_device();
        return err;
}

void cscfg_exit(void)
{
        cscfg_clear_device();
}