Implementing buffer API to update the location of the ETB
internal ring buffer once a trace session has ended.
Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
---
drivers/hwtracing/coresight/coresight-etb10.c | 128 ++++++++++++++++++++++++++
include/linux/coresight.h | 14 ++-
2 files changed, 137 insertions(+), 5 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index ca2c4b42464d..8e469d097955 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/circ_buf.h>
#include <linux/perf_event.h>
#include <asm/local.h>
@@ -362,12 +363,139 @@ static void etb_reset_buffer(struct coresight_device *csdev,
local_set(&drvdata->in_use, 0);
}
+static void etb_update_buffer(struct coresight_device *csdev,
+ struct perf_output_handle *handle,
+ void *sink_config)
+{
+ int i, cur;
+ u8 *buf_ptr;
+ u32 read_ptr, write_ptr, start;
+ u32 status, read_data, words;
+ unsigned long flags, offset;
+ struct cs_buffers *buf = sink_config;
+ struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+ if (!buf)
+ return;
+
+ spin_lock_irqsave(&drvdata->spinlock, flags);
+ if (!drvdata->enable)
+ goto out;
+
+ etb_disable_hw(drvdata);
+ CS_UNLOCK(drvdata->base);
+
+ /* unit is in words, not bytes */
+ read_ptr = readl_relaxed(drvdata->base + ETB_RAM_READ_POINTER);
+ write_ptr = readl_relaxed(drvdata->base + ETB_RAM_WRITE_POINTER);
+
+ /*
+ * Entries should be aligned to the frame size. If they are not
+ * go back to the last alignement point to give decoding tools a
+ * chance to fix things.
+ */
+ if (write_ptr % ETB_FRAME_SIZE_WORDS) {
+ dev_err(drvdata->dev,
+ "write_ptr: %lu not aligned to formatter frame size\n",
+ (unsigned long)write_ptr);
+
+ write_ptr &= ~ETB_FRAME_SIZE_WORDS;
+ local_inc(&buf->lost);
+ }
+
+ /*
+ * Get a hold of the status register and see if a wrap around
+ * has occurred. If so adjust things accordingly. Otherwise
+ * start at the beginning and go until the write pointer has
+ * been reached.
+ */
+ status = readl_relaxed(drvdata->base + ETB_STATUS_REG);
+ if (status & ETB_STATUS_RAM_FULL) {
+ local_inc(&buf->lost);
+ words = drvdata->buffer_depth;
+ start = write_ptr;
+ } else {
+ words = CIRC_CNT(write_ptr, read_ptr, drvdata->buffer_depth);
+ start = read_ptr;
+ }
+
+ /*
+ * Make sure we don't overwrite data that hasn't been consumed yet.
+ * It is entirely possible that the HW buffer has more data than the
+ * ring buffer can currently handle. If so adjust the start address
+ * to take only the last traces.
+ *
+ * In snapshot mode we are looking to get the latest traces only and as
+ * such, we don't care about not overwriting data that hasn't been
+ * processed by user space.
+ *
+ * Since metrics related to ETBs is in words, multiply by the
+ * amount of byte per word to have the right units.
+ */
+ if (!buf->snapshot && words * ETB_FRAME_SIZE_WORDS > handle->size) {
+ unsigned int capacity = drvdata->buffer_depth;
+
+ /* make sure new sizes are still multiples the frame size */
+ words = handle->size / ETB_FRAME_SIZE_WORDS;
+ /* advance the start pointer to get the latest trace data */
+ start += capacity - words;
+ /* wrap around if we've reach the end of the HW buffer */
+ start &= capacity - 1;
+ /* let the decoder know we've skipped ahead */
+ local_inc(&buf->lost);
+ }
+
+ /* finally tell HW where we want to start reading from */
+ writel_relaxed(start, drvdata->base + ETB_RAM_READ_POINTER);
+
+ cur = buf->cur;
+ offset = buf->offset;
+ for (i = 0; i < words; i++) {
+ buf_ptr = buf->addr[cur] + offset;
+ read_data = readl_relaxed(drvdata->base +
+ ETB_RAM_READ_DATA_REG);
+ *buf_ptr++ = read_data >> 0;
+ *buf_ptr++ = read_data >> 8;
+ *buf_ptr++ = read_data >> 16;
+ *buf_ptr++ = read_data >> 24;
+
+ offset += 4;
+ if (offset >= PAGE_SIZE) {
+ offset = 0;
+ cur++;
+ /* wrap around at the end of the buffer */
+ cur &= buf->nr_pages - 1;
+ }
+ }
+
+ /* reset ETB buffer for next run */
+ writel_relaxed(0x0, drvdata->base + ETB_RAM_READ_POINTER);
+ writel_relaxed(0x0, drvdata->base + ETB_RAM_WRITE_POINTER);
+
+ /*
+ * In snapshot mode all we have to do is communicate to
+ * perf_aux_output_end() the address of the current head. In full
+ * trace mode the same function expects a size to move rb->aux_head
+ * forward.
+ */
+ if (buf->snapshot)
+ local_set(&buf->data_size, (cur * PAGE_SIZE) + offset);
+ else
+ local_add(words * ETB_FRAME_SIZE_WORDS, &buf->data_size);
+
+ CS_LOCK(drvdata->base);
+ etb_enable_hw(drvdata);
+out:
+ spin_unlock_irqrestore(&drvdata->spinlock, flags);
+}
+
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,
+ .update_buffer = etb_update_buffer,
};
static const struct coresight_ops etb_cs_ops = {
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 78202d5ea58a..cdf401d51998 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -186,11 +186,12 @@ struct coresight_device {
/**
* struct coresight_ops_sink - basic operations for a sink
* Operations available for sinks
- * @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.
+ * @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.
+ * @update_buffer: update buffer pointers after a trace session.
*/
struct coresight_ops_sink {
int (*enable)(struct coresight_device *csdev);
@@ -203,6 +204,9 @@ struct coresight_ops_sink {
void (*reset_buffer)(struct coresight_device *csdev,
struct perf_output_handle *handle,
void *sink_config);
+ void (*update_buffer)(struct coresight_device *csdev,
+ struct perf_output_handle *handle,
+ void *sink_config);
};
/**
--
1.9.1
--
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