Hi Mathieu,

On Wed, 28 Jul 2021 at 17:24, Mathieu Poirier
[off-list ref] wrote:

On Fri, Jul 23, 2021 at 05:54:39PM +0100, Mike Leach wrote:

quoted

Configurations are first activated, then when any coresight device is
enabled, the active configurations are checked and any matching
one is enabled.

This patch provides the activation / enable API.

Signed-off-by: Mike Leach <redacted>
---
 .../hwtracing/coresight/coresight-config.h    |   2 +
 .../hwtracing/coresight/coresight-syscfg.c    | 212 ++++++++++++++++++
 .../hwtracing/coresight/coresight-syscfg.h    |   8 +
 include/linux/coresight.h                     |   2 +
 4 files changed, 224 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
index 0667581822c1..25eb6c632692 100644
--- a/drivers/hwtracing/coresight/coresight-config.h
+++ b/drivers/hwtracing/coresight/coresight-config.h

@@ -127,6 +127,7 @@ struct cscfg_feature_desc {
  * @nr_total_params: Sum of all parameters declared by used features
  * @presets:         Array of preset values.
  * @event_ea:                Extended attribute for perf event value
+ * @active_cnt:              ref count for activate on this configuration.
  *
  */
 struct cscfg_config_desc {

@@ -139,6 +140,7 @@ struct cscfg_config_desc {
      int nr_total_params;
      const u64 *presets; /* nr_presets * nr_total_params */
      struct dev_ext_attribute *event_ea;
+     atomic_t active_cnt;
 };

 /**

diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
index b93f2b4a777e..8903aab36c51 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.c
+++ b/drivers/hwtracing/coresight/coresight-syscfg.c

@@ -282,6 +282,7 @@ static int cscfg_load_config(struct cscfg_config_desc *config_desc)
              return err;

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

@@ -468,6 +469,216 @@ void cscfg_unregister_csdev(struct coresight_device *csdev)
 }
 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;
+
+     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:
+     spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
+}
+EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats);
+
+/**
+ * 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.
+ *
+ * Increments the configuration descriptor active count and the global active
+ * count.
+ *
+ * @cfg_hash: Hash value of the selected configuration name.
+ */
+int cscfg_activate_config(unsigned long cfg_hash)
+{
+     struct cscfg_config_desc *config_desc;
+     int err = -EINVAL;
+
+     mutex_lock(&cscfg_mutex);
+
+     list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
+             if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
+                     /*
+                      * increment the global active count - control changes to
+                      * active configurations
+                      */
+                     atomic_inc(&cscfg_mgr->sys_active_cnt);
+
+                     /*
+                      * mark the descriptor as active so enable config on a
+                      * device instance will use it
+                      */
+                     atomic_inc(&config_desc->active_cnt);
+
+                     err = 0;
+                     dev_dbg(cscfg_device(), "Activate config %s.\n", config_desc->name);
+                     break;
+             }
+     }
+     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)
+{
+     struct cscfg_config_desc *config_desc;
+
+     mutex_lock(&cscfg_mutex);
+
+     list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
+             if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
+                     atomic_dec(&config_desc->active_cnt);
+                     atomic_dec(&cscfg_mgr->sys_active_cnt);
+                     dev_dbg(cscfg_device(), "Deactivate config %s.\n", config_desc->name);
+                     break;
+             }
+     }
+     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;
+     const 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 config - set in_enable flag if found */

The second part of this comment no longer applies.

You are right - sorry missed that!

quoted

+     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 ((atomic_read(&config_desc->active_cnt)) &&
+                 ((unsigned long)config_desc->event_ea->var == cfg_hash)) {
+                     config_csdev_active = config_csdev_item;
+                     csdev->active_cscfg_ctxt = (void *)config_csdev_active;
+                     break;
+             }
+     }
+     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.
+                      */
+                     spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
+                     if (csdev->active_cscfg_ctxt)
+                             config_csdev_active->enabled = true;
+                     else
+                             err = -EBUSY;
+                     spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
+             }

This is much better.  I spent some time trying to break the heuristic and I
can't.  I intend to re-apply this set to give it as much exposure as possible but
want to see the above comment fixed.  I will do that locally though to avoid
having to deal with another revision.  What do you think of:

        /*
         * Look for a matching configuration - set the active configuration
         * context if found.
         */

That looks fin to me

Thanks

Mike

Thanks,
Mathieu

quoted

+     }
+     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.
+      */
+     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;
+     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);
+}
+EXPORT_SYMBOL_GPL(cscfg_csdev_disable_active_config);
+
 /* Initialise system configuration management device. */

 struct device *cscfg_device(void)

@@ -536,6 +747,7 @@ int __init cscfg_init(void)
      INIT_LIST_HEAD(&cscfg_mgr->csdev_desc_list);
      INIT_LIST_HEAD(&cscfg_mgr->feat_desc_list);
      INIT_LIST_HEAD(&cscfg_mgr->config_desc_list);
+     atomic_set(&cscfg_mgr->sys_active_cnt, 0);

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

diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h
index 5bcae3b374c6..a52775890670 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.h
+++ b/drivers/hwtracing/coresight/coresight-syscfg.h

@@ -24,12 +24,14 @@
  * @csdev_desc_list: List of coresight devices registered with the configuration manager.
  * @feat_desc_list:  List of feature descriptors to load into registered devices.
  * @config_desc_list:        List of system configuration descriptors to load into registered devices.
+ * @sys_active_cnt:  Total number of active config descriptor references.
  */
 struct cscfg_manager {
      struct device dev;
      struct list_head csdev_desc_list;
      struct list_head feat_desc_list;
      struct list_head config_desc_list;
+     atomic_t sys_active_cnt;
 };

 /* get reference to dev in cscfg_manager */

@@ -61,5 +63,11 @@ int cscfg_load_config_sets(struct cscfg_config_desc **cfg_descs,
 int cscfg_register_csdev(struct coresight_device *csdev, u32 match_flags,
                       struct cscfg_csdev_feat_ops *ops);
 void cscfg_unregister_csdev(struct coresight_device *csdev);
+int cscfg_activate_config(unsigned long cfg_hash);
+void cscfg_deactivate_config(unsigned long cfg_hash);
+void cscfg_csdev_reset_feats(struct coresight_device *csdev);
+int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
+                                  unsigned long cfg_hash, int preset);
+void cscfg_csdev_disable_active_config(struct coresight_device *csdev);

 #endif /* CORESIGHT_SYSCFG_H */

diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 16544ae2b532..93a2922b7653 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h

@@ -223,6 +223,7 @@ struct coresight_sysfs_link {
  * @feature_csdev_list: List of complex feature programming added to the device.
  * @config_csdev_list:  List of system configurations added to the device.
  * @cscfg_csdev_lock:        Protect the lists of configurations and features.
+ * @active_cscfg_ctxt:  Context information for current active system configuration.
  */
 struct coresight_device {
      struct coresight_platform_data *pdata;

@@ -248,6 +249,7 @@ struct coresight_device {
      struct list_head feature_csdev_list;
      struct list_head config_csdev_list;
      spinlock_t cscfg_csdev_lock;
+     void *active_cscfg_ctxt;
 };

 /*
--

2.17.1

-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK

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