added aux/icanhasmsi

sys/src/cmd/aux/icanhasmsi.c

@@ -0,0 +1,60 @@
+#include <u.h>
+#include <libc.h>
+
+int
+pcicfg16r(int fd, ushort *s, vlong offset)
+{
+	char buf[2];
+	
+	if(pread(fd, buf, 2, offset) < 2) return -1;
+	*s = buf[0] | (buf[1] << 8);
+	return 0;
+}
+
+void
+main()
+{
+	int fd;
+	long n;
+	Dir *dir;
+	char *p, *s;
+	uchar cap, c;
+	ushort sh;
+	
+	fd = open("/dev/pci", OREAD);
+	if(fd < 0) sysfatal("open /dev/pci: %r");
+	n = dirreadall(fd, &dir);
+	if(n < 0) sysfatal("dirreadall /dev/pci: %r");
+	close(fd);
+	for(; n--; dir++) {
+		p = dir->name + strlen(dir->name) - 3;
+		if(strcmp(p, "raw") != 0)
+			continue;
+		s = smprint("/dev/pci/%s", dir->name);
+		fd = open(s, OREAD);
+		if(fd < 0) {
+			fprint(2, "open %s: %r", s);
+			free(s);
+			continue;
+		}
+		if(pcicfg16r(fd, &sh, 0) < 0) goto err;
+		if(sh == 0xFFFF) goto end;
+		if(pcicfg16r(fd, &sh, 0x06) < 0) goto err;
+		if((sh & (1<<4)) == 0) goto end;
+		cap = 0x33;
+		for(;;) {
+			if(pread(fd, &cap, 1, cap+1) < 0) goto err;
+			if(cap == 0) goto end;
+			if(pread(fd, &c, 1, cap) < 0) goto err;
+			if(c == 0x05) break;
+		}
+		s[strlen(s) - 3] = 0;
+		print("%s\n", s+9);
+		goto end;
+	err:
+		fprint(2, "read %s: %r", s);
+	end:
+		free(s);
+		close(fd);
+	}
+}