Re: [PATCH v9 05/10] coresight: syscfg: Add API to activate and enable configurations

Hi Mathieu,

On Wed, 28 Jul 2021 at 17:24, Mathieu Poirier mathieu.poirier@linaro.org wrote:

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

...

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 mike.leach@linaro.org

.../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!

...

• 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

...

• }
  

• 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