intel/perf: Extern C

Allow libintel_perf to be included as a dependency from a C++ project by
wrapping some declaration within an extern "C" block, and then add a
function to allow direct reading of the OA stream.

v2: Don't expose internal helpers (Lionel)

Signed-off-by: Antonio Caggiano <antonio.caggiano@collabora.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10216>

src/intel/perf/intel_perf.h

@@ -41,6 +41,10 @@
 
 #include "drm-uapi/i915_drm.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct intel_device_info;
 
 struct intel_perf_config;
@@ -510,4 +514,8 @@ void intel_perf_get_counters_passes(struct intel_perf_config *perf,
                                     uint32_t counter_indices_count,
                                     struct intel_perf_counter_pass *counter_pass);
 
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
 #endif /* INTEL_PERF_H */

src/intel/perf/intel_perf_query.c

@@ -22,6 +22,7 @@
  */
 
 #include <unistd.h>
+#include <poll.h>
 
 #include "common/intel_gem.h"
 
@@ -347,7 +348,7 @@ dec_n_users(struct intel_perf_context *perf_ctx)
    }
 }
 
-static void
+void
 intel_perf_close(struct intel_perf_context *perfquery,
                  const struct intel_perf_query_info *query)
 {
@@ -355,20 +356,21 @@ intel_perf_close(struct intel_perf_context *perfquery,
       close(perfquery->oa_stream_fd);
       perfquery->oa_stream_fd = -1;
    }
-   if (query->kind == INTEL_PERF_QUERY_TYPE_RAW) {
+   if (query && query->kind == INTEL_PERF_QUERY_TYPE_RAW) {
       struct intel_perf_query_info *raw_query =
          (struct intel_perf_query_info *) query;
       raw_query->oa_metrics_set_id = 0;
    }
 }
 
-static bool
+bool
 intel_perf_open(struct intel_perf_context *perf_ctx,
                 int metrics_set_id,
                 int report_format,
                 int period_exponent,
                 int drm_fd,
-                uint32_t ctx_id)
+                uint32_t ctx_id,
+                bool enable)
 {
    uint64_t properties[DRM_I915_PERF_PROP_MAX * 2];
    uint32_t p = 0;
@@ -402,7 +404,7 @@ intel_perf_open(struct intel_perf_context *perf_ctx,
    struct drm_i915_perf_open_param param = {
       .flags = I915_PERF_FLAG_FD_CLOEXEC |
                I915_PERF_FLAG_FD_NONBLOCK |
-               I915_PERF_FLAG_DISABLED,
+               (enable ? 0 : I915_PERF_FLAG_DISABLED),
       .num_properties = p / 2,
       .properties_ptr = (uintptr_t) properties,
    };
@@ -417,6 +419,9 @@ intel_perf_open(struct intel_perf_context *perf_ctx,
    perf_ctx->current_oa_metrics_set_id = metrics_set_id;
    perf_ctx->current_oa_format = report_format;
 
+   if (enable)
+      ++perf_ctx->n_oa_users;
+
    return true;
 }
 
@@ -829,7 +834,7 @@ intel_perf_begin_query(struct intel_perf_context *perf_ctx,
 
          if (!intel_perf_open(perf_ctx, metric_id, queryinfo->oa_format,
                             perf_ctx->period_exponent, perf_ctx->drm_fd,
-                            perf_ctx->hw_ctx))
+                            perf_ctx->hw_ctx, false))
             return false;
       } else {
          assert(perf_ctx->current_oa_metrics_set_id == metric_id &&
@@ -958,6 +963,33 @@ intel_perf_end_query(struct intel_perf_context *perf_ctx,
    }
 }
 
+bool intel_perf_oa_stream_ready(struct intel_perf_context *perf_ctx)
+{
+   struct pollfd pfd;
+
+   pfd.fd = perf_ctx->oa_stream_fd;
+   pfd.events = POLLIN;
+   pfd.revents = 0;
+
+   if (poll(&pfd, 1, 0) < 0) {
+      DBG("Error polling OA stream\n");
+      return false;
+   }
+
+   if (!(pfd.revents & POLLIN))
+      return false;
+
+   return true;
+}
+
+ssize_t
+intel_perf_read_oa_stream(struct intel_perf_context *perf_ctx,
+                          void* buf,
+                          size_t nbytes)
+{
+   return read(perf_ctx->oa_stream_fd, buf, nbytes);
+}
+
 enum OaReadStatus {
    OA_READ_STATUS_ERROR,
    OA_READ_STATUS_UNFINISHED,

src/intel/perf/intel_perf_query.h

@@ -26,12 +26,36 @@
 
 #include <stdint.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct intel_device_info;
 
 struct intel_perf_config;
 struct intel_perf_context;
 struct intel_perf_query_object;
 
+bool
+intel_perf_open(struct intel_perf_context *perf_ctx,
+                int metrics_set_id,
+                int report_format,
+                int period_exponent,
+                int drm_fd,
+                uint32_t ctx_id,
+                bool enable);
+
+void
+intel_perf_close(struct intel_perf_context *perfquery,
+                 const struct intel_perf_query_info *query);
+
+bool intel_perf_oa_stream_ready(struct intel_perf_context *perf_ctx);
+
+ssize_t
+intel_perf_read_oa_stream(struct intel_perf_context *perf_ctx,
+                          void* buf,
+                          size_t nbytes);
+
 struct intel_perf_context *intel_perf_new_context(void *parent);
 
 void intel_perf_init_context(struct intel_perf_context *perf_ctx,
@@ -78,4 +102,8 @@ void intel_perf_dump_query(struct intel_perf_context *perf_ctx,
                            struct intel_perf_query_object *obj,
                            void *current_batch);
 
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
 #endif /* INTEL_PERF_QUERY_H */