Implementing perf related APIs to activate and terminate
a trace session. More specifically dealing with the sink
buffer's internal mechanic along with perf's API to start
and stop interactions with the ring buffers.
Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org>
---
drivers/hwtracing/coresight/coresight-etb10.c | 58 +++++++++++++++++++++++++++
include/linux/coresight.h | 9 +++++
2 files changed, 67 insertions(+)
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c
b/drivers/hwtracing/coresight/coresight-etb10.c
index 7f34e7af465e..ca2c4b42464d 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -28,6 +28,7 @@
#include <linux/amba/bus.h>
#include <linux/clk.h>
#include <linux/mm.h>
+#include <linux/perf_event.h>
#include <asm/local.h>
@@ -306,10 +307,67 @@ static void *etb_setup_aux(struct coresight_device
*csdev, int cpu,
return buf;
}
+static int etb_set_buffer(struct coresight_device *csdev,
+ struct perf_output_handle *handle,
+ void *sink_config)
+{
+ int ret = 0;
+ unsigned long head;
+ struct cs_buffers *buf = sink_config;
+ struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+ /* This sink can only be used by a single session */
+ if (local_xchg(&drvdata->in_use, 1))
+ return -EBUSY;
+
+ /* how much space do we have in this session */
+ buf->size = handle->size;
+
+ /* wrap head around to the amount of space we have */
+ head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1);
+
+ /* find the page to write to */
+ buf->cur = head / PAGE_SIZE;
+
+ /* and offset within that page */
+ buf->offset = head % PAGE_SIZE;
+
+ local_set(&buf->head, head);
+ local_set(&buf->data_size, 0);
+
+ return ret;
+}
+
+static void etb_reset_buffer(struct coresight_device *csdev,
+ struct perf_output_handle *handle,
+ void *sink_config)
+{
+ struct cs_buffers *buf = sink_config;
+ struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+ if (buf) {
+ /*
+ * In snapshot mode ->data_size holds the new address of the
+ * ring buffer's head. The size itself is the whole address
+ * range since we want the latest information.
+ */
+ if (buf->snapshot)
+ handle->head = local_xchg(&buf->data_size,
+ buf->nr_pages << PAGE_SHIFT);
+
+ perf_aux_output_end(handle, local_xchg(&buf->data_size, 0),
+ local_xchg(&buf->lost, 0));
+ }
+
+ local_set(&drvdata->in_use, 0);
+}
+
static const struct coresight_ops_sink etb_sink_ops = {
.enable = etb_enable,
.disable = etb_disable,
.setup_aux = etb_setup_aux,
+ .set_buffer = etb_set_buffer,
+ .reset_buffer = etb_reset_buffer,
};
static const struct coresight_ops etb_cs_ops = {
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index b1c25eba83b4..78202d5ea58a 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -15,6 +15,7 @@
#include <linux/device.h>
#include <linux/sched.h>
+#include <linux/perf_event.h>
/* Peripheral id registers (0xFD0-0xFEC) */
#define CORESIGHT_PERIPHIDR4 0xfd0
@@ -188,12 +189,20 @@ struct coresight_device {
* @enable: enables the sink.
* @disable: disables the sink.
* @setup_aux: initialises perf's ring buffer for trace collection.
+ * @set_buffer: initialises buffer mechanic before a trace session.
+ * @reset_buffer: finalises buffer mechanic after a trace session.
*/
struct coresight_ops_sink {
int (*enable)(struct coresight_device *csdev);
void (*disable)(struct coresight_device *csdev);
void *(*setup_aux)(struct coresight_device *csdev, int cpu,
void **pages, int nr_pages, bool overwrite);
+ int (*set_buffer)(struct coresight_device *csdev,
+ struct perf_output_handle *handle,
+ void *sink_config);
+ void (*reset_buffer)(struct coresight_device *csdev,
+ struct perf_output_handle *handle,
+ void *sink_config);
};
/**
--
1.9.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
