Re: [PATCH v4 05/10] coresight: syscfg: Add API to activate and enable configurations
From: Mathieu Poirier
Date: Thu Feb 25 2021 - 16:21:43 EST
On Thu, Jan 28, 2021 at 05:09:31PM +0000, Mike Leach wrote:
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Configurations are first activated, then when any coresight device is
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enabled, the active configurations are checked and any matching
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one is enabled.
>
>
This patch provides the activation / enable API.
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>
Signed-off-by: Mike Leach <mike.leach@xxxxxxxxxx>
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---
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.../hwtracing/coresight/coresight-config.h | 2 +
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.../hwtracing/coresight/coresight-syscfg.c | 127 ++++++++++++++++++
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.../hwtracing/coresight/coresight-syscfg.h | 10 +-
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include/linux/coresight.h | 2 +
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4 files changed, 140 insertions(+), 1 deletion(-)
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>
diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
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index 98380b496046..26396b70c826 100644
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--- a/drivers/hwtracing/coresight/coresight-config.h
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+++ b/drivers/hwtracing/coresight/coresight-config.h
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@@ -156,6 +156,7 @@ struct cscfg_config_feat_ref {
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* @presets: Array of preset values.
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* @id_ea: Extended attribute for perf configid value
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* @event_ea: Extended attribute for perf event value
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+ * @active_cnt: ref count for activate on this configuration.
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*/
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struct cscfg_config_desc {
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const char *name;
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@@ -168,6 +169,7 @@ struct cscfg_config_desc {
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const u64 *presets; /* nr_presets * nr_total_params */
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struct dev_ext_attribute *id_ea;
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struct dev_ext_attribute *event_ea;
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+ atomic_t active_cnt;
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};
>
>
/**
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diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
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index a070f135eca3..d79cf5b36758 100644
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--- a/drivers/hwtracing/coresight/coresight-syscfg.c
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+++ b/drivers/hwtracing/coresight/coresight-syscfg.c
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@@ -298,6 +298,7 @@ static int cscfg_load_config(struct cscfg_config_desc *cfg_desc)
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return err;
>
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list_add(&cfg_desc->item, &cscfg_mgr->data.config_desc_list);
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+ atomic_set(&cfg_desc->active_cnt, 0);
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return 0;
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}
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>
@@ -477,6 +478,131 @@ void cscfg_unregister_csdev(struct coresight_device *csdev)
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}
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EXPORT_SYMBOL_GPL(cscfg_unregister_csdev);
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>
+void cscfg_csdev_reset_feats(struct coresight_device *csdev)
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+{
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+ struct cscfg_feature_csdev *feat;
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+
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+ mutex_lock(&cscfg_csdev_mutex);
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+ if (list_empty(&csdev->feature_csdev_list))
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+ goto unlock_exit;
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+
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+ list_for_each_entry(feat, &csdev->feature_csdev_list, node)
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+ cscfg_reset_feat(feat);
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+
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+unlock_exit:
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+ mutex_unlock(&cscfg_csdev_mutex);
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+}
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+EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats);
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+
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+/**
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+ * Mark a config descriptor as active.
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+ * This will be seen when csdev devices are activated in the system.
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+ *
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+ * Selection by hash value - generated from the configuration name when it
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+ * was loaded and added to the cs_etm/configurations file system for selection
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+ * by perf.
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+ *
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+ * @cfg_hash: Hash value of the selected configuration name.
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+ */
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+int cscfg_activate_config(unsigned long cfg_hash)
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+{
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+ struct cscfg_config_desc *curr_item, *match_item = 0;
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+
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+ mutex_lock(&cscfg_mutex);
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+
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+ list_for_each_entry(curr_item, &cscfg_mgr->data.config_desc_list, item) {
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+ if ((unsigned long)curr_item->id_ea->var == cfg_hash) {
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+ match_item = curr_item;
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+ atomic_inc(&cscfg_mgr->data.sys_active_cnt);
It would be nice to have a comment that mentions why this is needed. I had to
go look in patch 09 to see that it prevents a feature from being changed when
any configuration is active. And since patch 09 is the only place where
@sys_active_cnt is used, please move the declaration and handling of the
variable there.
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+ break;
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+ }
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+ }
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+ mutex_unlock(&cscfg_mutex);
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+
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+ if (!match_item)
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+ return -EINVAL;
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+
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+ dev_dbg(to_device_cscfg(), "Activate config %s.\n", match_item->name);
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+
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+ /* mark the descriptors as active so enable config will use them */
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+ mutex_lock(&cscfg_csdev_mutex);
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+ atomic_inc(&match_item->active_cnt);
What is ->active_cnt used for? I see it referenced in
cscfg_csdev_enable_active_config() but it doesn't do much other than to confirm
the configuration has been activated by someone.
There is also a chance that a caller would call cscfg_activate_config() once and
call cscfg_csdev_enable_active_config() multiple time, which would really create
problems. I would move the incrementation of sys_active_cnt within the mutex
hold in cscfg_csdev_enable_active_config() and get rid of ->active_cnt. If I am
correct we wouldn't need cscfg_activate_config() after that.
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+ mutex_unlock(&cscfg_csdev_mutex);
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+
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+ return 0;
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+}
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+EXPORT_SYMBOL_GPL(cscfg_activate_config);
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+
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+void cscfg_deactivate_config(unsigned long cfg_hash)
I'm fine with either cfg_hash or id_hash, but not both.
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+{
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+ struct cscfg_config_desc *curr_item, *match_item = 0;
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+
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+ mutex_lock(&cscfg_mutex);
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+
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+ list_for_each_entry(curr_item, &cscfg_mgr->data.config_desc_list, item) {
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+ if ((unsigned long)curr_item->id_ea->var == cfg_hash) {
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+ match_item = curr_item;
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+ break;
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+ }
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+ }
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+ mutex_unlock(&cscfg_mutex);
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+ if (!match_item)
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+ return;
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+
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+ dev_dbg(to_device_cscfg(), "Deactivate config %s.\n", match_item->name);
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+
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+ mutex_lock(&cscfg_csdev_mutex);
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+ atomic_dec(&match_item->active_cnt);
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+ mutex_unlock(&cscfg_csdev_mutex);
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+
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+ atomic_dec(&cscfg_mgr->data.sys_active_cnt);
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+}
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+EXPORT_SYMBOL_GPL(cscfg_deactivate_config);
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+
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+/* Find and program any active config for the supplied device.*/
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+int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
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+ unsigned long id_hash, int preset)
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+{
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+ struct cscfg_config_csdev *cfg = NULL, *item;
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+ const struct cscfg_config_desc *desc;
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+ int err = 0;
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+
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+ /* quickly check global count */
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+ if (!atomic_read(&cscfg_mgr->data.sys_active_cnt))
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+ return 0;
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+
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+ mutex_lock(&cscfg_csdev_mutex);
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+ list_for_each_entry(item, &csdev->config_csdev_list, node) {
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+ desc = item->desc;
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+ if ((atomic_read(&desc->active_cnt)) &&
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+ ((unsigned long)desc->id_ea->var == id_hash)) {
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+ cfg = item;
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+ break;
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+ }
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+ }
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+ if (cfg) {
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+ err = cscfg_csdev_enable_config(cfg, preset);
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+ if (!err)
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+ csdev->active_cfg_ctxt = (void *)cfg;
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+ }
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+ mutex_unlock(&cscfg_csdev_mutex);
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+ return err;
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+}
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+EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config);
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+
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+/* save and disable the active config for the device */
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+void cscfg_csdev_disable_active_config(struct coresight_device *csdev)
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+{
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+ struct cscfg_config_csdev *cfg;
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+
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+ mutex_lock(&cscfg_csdev_mutex);
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+ cfg = (struct cscfg_config_csdev *)csdev->active_cfg_ctxt;
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+ if (cfg)
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+ cscfg_csdev_disable_config(cfg);
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+ mutex_unlock(&cscfg_csdev_mutex);
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+}
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+EXPORT_SYMBOL_GPL(cscfg_csdev_disable_active_config);
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+
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/* Initialise system configuration management device. */
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>
struct device *to_device_cscfg(void)
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@@ -546,6 +672,7 @@ int __init cscfg_init(void)
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INIT_LIST_HEAD(&cscfg_mgr->data.feat_desc_list);
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INIT_LIST_HEAD(&cscfg_mgr->data.config_desc_list);
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cscfg_mgr->data.nr_csdev = 0;
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+ atomic_set(&cscfg_mgr->data.sys_active_cnt, 0);
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dev_info(to_device_cscfg(), "CoreSight Configuration manager initialised");
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return 0;
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diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h
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index ebf5e1491d86..301e26e1e98f 100644
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--- a/drivers/hwtracing/coresight/coresight-syscfg.h
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+++ b/drivers/hwtracing/coresight/coresight-syscfg.h
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@@ -17,13 +17,15 @@
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* @csdev_list: List of coresight devices registered with the configuration manager.
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* @feat_desc_list: List of feature descriptors to load into registered devices.
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* @config_desc_list: List of system configuration descriptors to load into registered devices.
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- * @nr_csdev: Number of registered devices with the cscfg system
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+ * @nr_csdev: Number of registered devices with the cscfg system
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+ * @sys_active_cnt: Total number of active config descriptor references.
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*/
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struct cscfg_api_data {
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struct list_head csdev_desc_list;
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struct list_head feat_desc_list;
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struct list_head config_desc_list;
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int nr_csdev;
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+ atomic_t sys_active_cnt;
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};
>
>
/**
>
@@ -53,6 +55,12 @@ int cscfg_register_csdev(struct coresight_device *csdev,
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struct cscfg_match_desc *info,
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struct cscfg_csdev_feat_ops *ops);
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void cscfg_unregister_csdev(struct coresight_device *csdev);
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+int cscfg_activate_config(unsigned long cfg_hash);
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+void cscfg_deactivate_config(unsigned long cfg_hash);
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+void cscfg_csdev_reset_feats(struct coresight_device *csdev);
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+int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
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+ unsigned long id_hash, int preset);
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+void cscfg_csdev_disable_active_config(struct coresight_device *csdev);
>
>
/**
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* System configuration manager device.
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diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>
index d0126ed326a6..3941854e8280 100644
>
--- a/include/linux/coresight.h
>
+++ b/include/linux/coresight.h
>
@@ -221,6 +221,7 @@ struct coresight_sysfs_link {
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* @has_conns_grp: Have added a "connections" group for sysfs links.
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* @feature_csdev_list: List of complex feature programming added to the device.
>
* @config_csdev_list: List of system configurations added to the device.
>
+ * @active_cfg_ctxt: Context information for current active congfig.
>
*/
>
struct coresight_device {
>
struct coresight_platform_data *pdata;
>
@@ -245,6 +246,7 @@ struct coresight_device {
>
/* system configuration and feature lists */
>
struct list_head feature_csdev_list;
>
struct list_head config_csdev_list;
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+ void *active_cfg_ctxt;
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};
>
>
/*
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--
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2.17.1
>