Re: [PATCH v4 08/10] coresight: add a new function in helper_ops

On 8/6/2025 8:35 AM, Jie Gan wrote:

On 8/5/2025 8:30 PM, Mike Leach wrote:

quoted

Hi,

On Fri, 25 Jul 2025 at 11:08, Jie Gan [off-list ref] wrote:

quoted

Add a new function to identifiy whether the byte-cntr function is
enabled or not in helper_ops.

The byte-cntr's read_ops is expected if the byte-cntr is enabled when
the user try to read trace data via sysfs node.

Signed-off-by: Jie Gan <redacted>
---
  .../hwtracing/coresight/coresight-ctcu-core.c | 35 +++++++++++++++++++
  include/linux/coresight.h                     |  3 ++
  2 files changed, 38 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-ctcu-core.c b/ 

drivers/hwtracing/coresight/coresight-ctcu-core.c
index 8fc08e42187e..dec911980939 100644

--- a/drivers/hwtracing/coresight/coresight-ctcu-core.c
+++ b/drivers/hwtracing/coresight/coresight-ctcu-core.c

@@ -234,9 +234,44 @@ static int ctcu_disable(struct coresight_device 

*csdev, void *data)
         return ctcu_set_etr_traceid(csdev, path, false);
  }

+static bool ctcu_qcom_byte_cntr_in_use(struct coresight_device *csdev,
+                                      void **data)
+{
+       struct ctcu_byte_cntr *byte_cntr_data;
+       struct coresight_device *helper;
+       struct ctcu_drvdata *drvdata;
+       int port;
+
+       if (!csdev)
+               return false;
+
+       helper = coresight_get_helper(csdev, 
CORESIGHT_DEV_SUBTYPE_HELPER_CTCU);
+       if (!helper)
+               return false;
+
+       port = coresight_get_in_port_dest(csdev, helper);
+       if (port < 0)
+               return false;
+
+       drvdata = dev_get_drvdata(helper->dev.parent);
+       /* Something wrong when initialize byte_cntr_read_ops */
+       if (!drvdata->byte_cntr_read_ops)
+               return false;
+
+       byte_cntr_data = &drvdata->byte_cntr_data[port];
+       /* Return the pointer of the ctcu_drvdata if byte-cntr has 
enabled */
+       if (byte_cntr_data && byte_cntr_data->thresh_val) {
+               *data = (void *)drvdata->byte_cntr_read_ops;
+               return true;
+       }
+
+       return false;
+}
+
  static const struct coresight_ops_helper ctcu_helper_ops = {
         .enable = ctcu_enable,
         .disable = ctcu_disable,
+       .qcom_byte_cntr_in_use = ctcu_qcom_byte_cntr_in_use,

These ops structures are for generic functions used throughout the
devices. Do not put this function here.

This is a specific ctcu helper. Make it external to the file and
declare it in coresight-ctcu.h

Will address the comment in next version.

Hi Mike
Cant add an external function in ctcu-core.c and called in tmc-core.c 
because there is a cycle dependency error:
depmod: ERROR: Cycle detected: coresight_tmc -> coresight_ctcu -> 
coresight_tmc
depmod: ERROR: Found 2 modules in dependency cycles!

How about I add a function in tmc-core.c to directly retrieving the 
sysfs_read_ops of the byte-cntr?

like below:
/* Return the byte-cntr's sysfs_read_ops if in use */
static const struct sysfs_read_ops *tmc_qcom_byte_cntr_in_use(struct 
tmc_drvdata *drvdata)
{
         struct ctcu_byte_cntr *byte_cntr_data;
         struct ctcu_drvdata *ctcu_drvdata;
         struct coresight_device *helper;
         int port;

         helper = coresight_get_helper(drvdata->csdev, 
CORESIGHT_DEV_SUBTYPE_HELPER_CTCU);
         if (!helper)
                 return NULL;

         port = coresight_get_in_port_dest(drvdata->csdev, helper);
         if (port < 0)
                 return NULL;

         ctcu_drvdata = dev_get_drvdata(helper->dev.parent);
         byte_cntr_data = &ctcu_drvdata->byte_cntr_data[port];
         if (byte_cntr_data && byte_cntr_data->thresh_val)
                 return ctcu_drvdata->byte_cntr_sysfs_read_ops;

         return NULL;
}

Thanks,
Jie

Thanks,
Jie

quoted

Mike

quoted

  };

  static const struct coresight_ops ctcu_ops = {

diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 4ac65c68bbf4..b5f052854b08 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h

@@ -419,11 +419,14 @@ struct coresight_ops_source {

   *
   * @enable     : Enable the device
   * @disable    : Disable the device
+ * @qcom_byte_cntr_in_use:     check whether the byte-cntr is enabled.
   */
  struct coresight_ops_helper {
         int (*enable)(struct coresight_device *csdev, enum cs_mode 
mode,
                       void *data);
         int (*disable)(struct coresight_device *csdev, void *data);
+       bool (*qcom_byte_cntr_in_use)(struct coresight_device *csdev,
+                                     void **data);
  };


-- 
2.34.1