overlay: Parse /proc/interrupts in lieu of debugfs/i915_gem_interrupt

So the interrupt counter was removed from i915_gem_interrupt, and if we
do not have the perf API available, we therefore need to read it from
/proc/interrupts instead.

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

1 files changed, 73 insertions, 28 deletions

diff --git a/overlay/gem-interrupts.c b/overlay/gem-interrupts.c
index 15dc7919..48a36b85 100644
--- a/overlay/gem-interrupts.c
+++ b/overlay/gem-interrupts.c
@@ -29,6 +29,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <ctype.h>
 
 #include "gem-interrupts.h"
 #include "debugfs.h"
@@ -48,16 +49,77 @@ static int perf_open(void)
 	return perf_event_open(&attr, -1, 0, -1, 0);
 }
 
-static int debugfs_open(void)
+static long long debugfs_read(void)
 {
-	char buf[1024];
-	struct stat st;
+	char buf[8192], *b;
+	int fd, len;
 
 	sprintf(buf, "%s/i915_gem_interrupt", debugfs_dri_path);
-	if (stat(buf, &st))
-		return errno;
+	fd = open(buf, 0);
+	if (fd < 0)
+		return -1;
 
-	return 0;
+	len = read(fd, buf, sizeof(buf)-1);
+	close(fd);
+
+	if (len < 0)
+		return -1;
+
+	buf[len] = '\0';
+
+	b = strstr(buf, "Interrupts received:");
+	if (b == NULL)
+		return -1;
+
+	return strtoull(b + sizeof("Interrupts received:"), 0, 0);
+}
+
+static long long procfs_read(void)
+{
+	char buf[8192], *b;
+	int fd, len;
+	unsigned long long val;
+
+/* 44:         51      42446          0          0   PCI-MSI-edge      i915*/
+	fd = open("/proc/interrupts", 0);
+	if (fd < 0)
+		return -1;
+
+	len = read(fd, buf, sizeof(buf)-1);
+	close(fd);
+
+	if (len < 0)
+		return -1;
+
+	buf[len] = '\0';
+
+	b = strstr(buf, "i915");
+	if (b == NULL)
+		return -1;
+	while (*--b != ':')
+		;
+
+	val = 0;
+	do {
+		while (isspace(*++b))
+			;
+		if (!isdigit(*b))
+			break;
+
+		val += strtoull(b, &b, 0);
+	} while(1);
+
+	return val;
+}
+
+static long long interrupts_read(void)
+{
+	long long val;
+
+	val = debugfs_read();
+	if (val < 0)
+		val = procfs_read();
+	return val;
 }
 
 int gem_interrupts_init(struct gem_interrupts *irqs)
@@ -65,8 +127,8 @@ int gem_interrupts_init(struct gem_interrupts *irqs)
 	memset(irqs, 0, sizeof(*irqs));
 
 	irqs->fd = perf_open();
-	if (irqs->fd < 0)
-		irqs->error = debugfs_open();
+	if (irqs->fd < 0 && interrupts_read() < 0)
+		irqs->error = ENODEV;
 
 	return irqs->error;
 }
@@ -80,26 +142,9 @@ int gem_interrupts_update(struct gem_interrupts *irqs)
 		return irqs->error;
 
 	if (irqs->fd < 0) {
-		char buf[8192], *b;
-		int fd, len;
-
-		sprintf(buf, "%s/i915_gem_interrupt", debugfs_dri_path);
-		fd = open(buf, 0);
-		if (fd < 0)
-			return irqs->error = errno;
-		len = read(fd, buf, sizeof(buf)-1);
-		close(fd);
-
-		if (len < 0)
-			return irqs->error = errno;
-
-		buf[len] = '\0';
-
-		b = strstr(buf, "Interrupts received:");
-		if (b == NULL)
-			return irqs->error = ENOENT;
-
-		val = strtoull(b + sizeof("Interrupts received:"), 0, 0);
+		val = interrupts_read();
+		if (val < 0)
+			return irqs->error = ENODEV;
 	} else {
 		if (read(irqs->fd, &val, sizeof(val)) < 0)
 			return irqs->error = errno;