[PATCH v1 1/4] coresight: tmc: Introduce new APIs to get the RWP offset of ETR buffer

[Jie Gan]

The new functions calculate and return the offset to the write pointer of
the ETR buffer based on whether the memory mode is SG, flat or reserved.
The functions have the RWP offset can directly read data from ETR buffer,
enabling the transfer of data to any required location.

Signed-off-by: Jie Gan <quic_jiegan@xxxxxxxxxxx>
---
 .../hwtracing/coresight/coresight-tmc-etr.c   | 40 +++++++++++++++++++
 drivers/hwtracing/coresight/coresight-tmc.h   |  1 +
 2 files changed, 41 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index eda7cdad0e2b..ec636ab1fd75 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -267,6 +267,46 @@ void tmc_free_sg_table(struct tmc_sg_table *sg_table)
 }
 EXPORT_SYMBOL_GPL(tmc_free_sg_table);
 
+static long tmc_flat_resrv_get_rwp_offset(struct tmc_drvdata *drvdata)
+{
+	dma_addr_t paddr = drvdata->sysfs_buf->hwaddr;
+	u64 rwp;
+
+	rwp = tmc_read_rwp(drvdata);
+	return rwp - paddr;
+}
+
+static long tmc_sg_get_rwp_offset(struct tmc_drvdata *drvdata)
+{
+	struct etr_buf *etr_buf = drvdata->sysfs_buf;
+	struct etr_sg_table *etr_table = etr_buf->private;
+	struct tmc_sg_table *table = etr_table->sg_table;
+	long w_offset;
+	u64 rwp;
+
+	rwp = tmc_read_rwp(drvdata);
+	w_offset = tmc_sg_get_data_page_offset(table, rwp);
+
+	return w_offset;
+}
+
+/*
+ * Retrieve the offset to the write pointer of the ETR buffer based on whether
+ * the memory mode is SG, flat or reserved.
+ */
+long tmc_get_rwp_offset(struct tmc_drvdata *drvdata)
+{
+	struct etr_buf *etr_buf = drvdata->sysfs_buf;
+
+	if (etr_buf->mode == ETR_MODE_ETR_SG)
+		return tmc_sg_get_rwp_offset(drvdata);
+	else if (etr_buf->mode == ETR_MODE_FLAT || etr_buf->mode == ETR_MODE_RESRV)
+		return tmc_flat_resrv_get_rwp_offset(drvdata);
+	else
+		return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(tmc_get_rwp_offset);
+
 /*
  * Alloc pages for the table. Since this will be used by the device,
  * allocate the pages closer to the device (i.e, dev_to_node(dev)
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index b48bc9a01cc0..baedb4dcfc3f 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -442,5 +442,6 @@ void tmc_etr_remove_catu_ops(void);
 struct etr_buf *tmc_etr_get_buffer(struct coresight_device *csdev,
 				   enum cs_mode mode, void *data);
 extern const struct attribute_group coresight_etr_group;
+long tmc_get_rwp_offset(struct tmc_drvdata *drvdata);
 
 #endif
-- 
2.34.1