overlay: Add rc6 residency

Not much point at the moment since we use forcewake to continuously
probe the GPU busyness. But that will eventually change to a more
power-efficient in-kernel.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 93 insertions, 0 deletions

diff --git a/overlay/rc6.c b/overlay/rc6.c
new file mode 100644
index 00000000..54e8594d
--- /dev/null
+++ b/overlay/rc6.c
@@ -0,0 +1,93 @@
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <time.h>
+#include <errno.h>
+
+#include "rc6.h"
+
+int rc6_init(struct rc6 *rc6)
+{
+	struct stat st;
+	int fd;
+
+	memset(rc6, 0, sizeof(*rc6));
+
+	fd = stat("/sys/class/drm/card0/power", &st);
+	if (fd == -1)
+		return rc6->error = errno;
+
+	return 0;
+}
+
+static uint64_t file_to_u64(const char *path)
+{
+	char buf[4096];
+	int fd, len;
+
+	fd = open(path, 0);
+	if (fd < 0)
+		return 0;
+
+	len = read(fd, buf, sizeof(buf)-1);
+	close(fd);
+
+	if (len < 0)
+		return 0;
+
+	buf[len] = '\0';
+
+	return strtoull(buf, 0, 0);
+}
+
+static uint64_t clock_ms_to_u64(void)
+{
+	struct timespec tv;
+
+	if (clock_gettime(CLOCK_MONOTONIC, &tv) < 0)
+		return 0;
+
+	return (uint64_t)tv.tv_sec * 1000 + tv.tv_nsec / 10000000;
+}
+
+int rc6_update(struct rc6 *rc6)
+{
+	struct rc6_stat *s = &rc6->stat[rc6->count++&1];
+	struct rc6_stat *d = &rc6->stat[rc6->count&1];
+	uint64_t d_time, d_rc6, d_rc6p, d_rc6pp;
+	struct stat st;
+
+	if (rc6->error)
+		return rc6->error;
+
+	if (stat("/sys/class/drm/card0/power", &st) < 0)
+		return rc6->error = errno;
+
+	if (stat("/sys/class/drm/card0/power/rc6_residency_ms", &st) < 0)
+		return ENOENT;
+
+	s->rc6_residency = file_to_u64("/sys/class/drm/card0/power/rc6_residency_ms");
+	s->rc6p_residency = file_to_u64("/sys/class/drm/card0/power/rc6p_residency_ms");
+	s->rc6pp_residency = file_to_u64("/sys/class/drm/card0/power/rc6pp_residency_ms");
+	s->timestamp = clock_ms_to_u64();
+
+	if (rc6->count == 1)
+		return EAGAIN;
+
+	d_time = s->timestamp - d->timestamp;
+
+	d_rc6 = s->rc6_residency - d->rc6_residency;
+	rc6->rc6 = 100 * d_rc6 / d_time;
+
+	d_rc6p = s->rc6p_residency - d->rc6p_residency;
+	rc6->rc6p = 100 * d_rc6p / d_time;
+
+	d_rc6pp = s->rc6pp_residency - d->rc6pp_residency;
+	rc6->rc6pp = 100 * d_rc6pp / d_time;
+
+	rc6->rc6_combined = 100 * (d_rc6 + d_rc6p + d_rc6pp) / d_time;
+	return 0;
+}