coresight: tmc: implementing TMC-ETF AUX space API

This patch implement the AUX area interfaces required to
use the TMC (configured as an ETF) from the Perf sub-system.

The heuristic is heavily borrowed from the ETB10 implementation.

Signed-off-by: Mathieu Poirier <[email protected]>
Reviewed-by: Suzuki K Poulose <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/hwtracing/coresight/coresight-tmc-etf.c

@@ -15,7 +15,9 @@
  * this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/circ_buf.h>
 #include <linux/coresight.h>
+#include <linux/perf_event.h>
 #include <linux/slab.h>
 #include "coresight-priv.h"
 #include "coresight-tmc.h"
@@ -282,9 +284,206 @@ static void tmc_disable_etf_link(struct coresight_device *csdev,
  dev_info(drvdata->dev, "TMC disabled\n");
 }
 
+static void *tmc_alloc_etf_buffer(struct coresight_device *csdev, int cpu,
+ void **pages, int nr_pages, bool overwrite)
+{
+ int node;
+ struct cs_buffers *buf;
+
+ if (cpu == -1)
+ cpu = smp_processor_id();
+ node = cpu_to_node(cpu);
+
+ /* Allocate memory structure for interaction with Perf */
+ buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
+ if (!buf)
+ return NULL;
+
+ buf->snapshot = overwrite;
+ buf->nr_pages = nr_pages;
+ buf->data_pages = pages;
+
+ return buf;
+}
+
+static void tmc_free_etf_buffer(void *config)
+{
+ struct cs_buffers *buf = config;
+
+ kfree(buf);
+}
+
+static int tmc_set_etf_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;
+
+ /* 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->data_size, 0);
+
+ return ret;
+}
+
+static unsigned long tmc_reset_etf_buffer(struct coresight_device *csdev,
+ struct perf_output_handle *handle,
+ void *sink_config, bool *lost)
+{
+ long size = 0;
+ struct cs_buffers *buf = sink_config;
+
+ 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);
+ /*
+ * Tell the tracer PMU how much we got in this run and if
+ * something went wrong along the way. Nobody else can use
+ * this cs_buffers instance until we are done. As such
+ * resetting parameters here and squaring off with the ring
+ * buffer API in the tracer PMU is fine.
+ */
+ *lost = !!local_xchg(&buf->lost, 0);
+ size = local_xchg(&buf->data_size, 0);
+ }
+
+ return size;
+}
+
+static void tmc_update_etf_buffer(struct coresight_device *csdev,
+ struct perf_output_handle *handle,
+ void *sink_config)
+{
+ int i, cur;
+ u32 *buf_ptr;
+ u32 read_ptr, write_ptr;
+ u32 status, to_read;
+ unsigned long offset;
+ struct cs_buffers *buf = sink_config;
+ struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+ if (!buf)
+ return;
+
+ /* This shouldn't happen */
+ if (WARN_ON_ONCE(local_read(&drvdata->mode) != CS_MODE_PERF))
+ return;
+
+ CS_UNLOCK(drvdata->base);
+
+ tmc_flush_and_stop(drvdata);
+
+ read_ptr = readl_relaxed(drvdata->base + TMC_RRP);
+ write_ptr = readl_relaxed(drvdata->base + TMC_RWP);
+
+ /*
+ * Get a hold of the status register and see if a wrap around
+ * has occurred. If so adjust things accordingly.
+ */
+ status = readl_relaxed(drvdata->base + TMC_STS);
+ if (status & TMC_STS_FULL) {
+ local_inc(&buf->lost);
+ to_read = drvdata->size;
+ } else {
+ to_read = CIRC_CNT(write_ptr, read_ptr, drvdata->size);
+ }
+
+ /*
+ * The TMC RAM buffer may be bigger than the space available in the
+ * perf ring buffer (handle->size). If so advance the RRP so that we
+ * get the latest trace data.
+ */
+ if (to_read > handle->size) {
+ u32 mask = 0;
+
+ /*
+ * The value written to RRP must be byte-address aligned to
+ * the width of the trace memory databus _and_ to a frame
+ * boundary (16 byte), whichever is the biggest. For example,
+ * for 32-bit, 64-bit and 128-bit wide trace memory, the four
+ * LSBs must be 0s. For 256-bit wide trace memory, the five
+ * LSBs must be 0s.
+ */
+ switch (drvdata->memwidth) {
+ case TMC_MEM_INTF_WIDTH_32BITS:
+ case TMC_MEM_INTF_WIDTH_64BITS:
+ case TMC_MEM_INTF_WIDTH_128BITS:
+ mask = GENMASK(31, 5);
+ break;
+ case TMC_MEM_INTF_WIDTH_256BITS:
+ mask = GENMASK(31, 6);
+ break;
+ }
+
+ /*
+ * Make sure the new size is aligned in accordance with the
+ * requirement explained above.
+ */
+ to_read = handle->size & mask;
+ /* Move the RAM read pointer up */
+ read_ptr = (write_ptr + drvdata->size) - to_read;
+ /* Make sure we are still within our limits */
+ if (read_ptr > (drvdata->size - 1))
+ read_ptr -= drvdata->size;
+ /* Tell the HW */
+ writel_relaxed(read_ptr, drvdata->base + TMC_RRP);
+ local_inc(&buf->lost);
+ }
+
+ cur = buf->cur;
+ offset = buf->offset;
+
+ /* for every byte to read */
+ for (i = 0; i < to_read; i += 4) {
+ buf_ptr = buf->data_pages[cur] + offset;
+ *buf_ptr = readl_relaxed(drvdata->base + TMC_RRD);
+
+ offset += 4;
+ if (offset >= PAGE_SIZE) {
+ offset = 0;
+ cur++;
+ /* wrap around at the end of the buffer */
+ cur &= buf->nr_pages - 1;
+ }
+ }
+
+ /*
+ * 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(to_read, &buf->data_size);
+
+ CS_LOCK(drvdata->base);
+}
+
 static const struct coresight_ops_sink tmc_etf_sink_ops = {
  .enable = tmc_enable_etf_sink,
  .disable = tmc_disable_etf_sink,
+ .alloc_buffer = tmc_alloc_etf_buffer,
+ .free_buffer = tmc_free_etf_buffer,
+ .set_buffer = tmc_set_etf_buffer,
+ .reset_buffer = tmc_reset_etf_buffer,
+ .update_buffer = tmc_update_etf_buffer,
 };
 
 static const struct coresight_ops_link tmc_etf_link_ops = {

drivers/hwtracing/coresight/coresight-tmc.h

@@ -52,6 +52,7 @@
 #define TMC_CTL_CAPT_EN BIT(0)
 /* TMC_STS - 0x00C */
 #define TMC_STS_TMCREADY_BIT 2
+#define TMC_STS_FULL BIT(0)
 #define TMC_STS_TRIGGERED BIT(1)
 /* TMC_AXICTL - 0x110 */
 #define TMC_AXICTL_PROT_CTL_B0 BIT(0)