bcm64: add gisb arbiter driver to catch bus timeouts

sys/src/9/bcm64/gisb.c

@@ -0,0 +1,63 @@
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "../port/error.h"
+#include "ureg.h"
+
+/*
+ * GISB arbiter registers
+ */
+static u32int *regs = (u32int*)(VIRTIO2 + 0x400000);
+
+enum {
+	ArbTimer	= 0x008/4,
+	ArbErrCapClear	= 0x7e4/4,
+	ArbErrCapAddrHi	= 0x7e8/4,
+	ArbErrCapAddr	= 0x7ec/4,
+	ArbErrCapStatus	= 0x7f4/4,
+		CapStatusTimeout	= 1<<12,
+		CapStatusAbort		= 1<<11,
+		CapStatusWrite		= 1<<1,
+		CapStatusValid		= 1<<0,
+	ArbErrCapMaster	= 0x7f8/4,
+};
+
+static int
+arbinterrupt(Ureg *)
+{
+	u32int status = regs[ArbErrCapStatus];
+	u32int master;
+	uvlong addr;
+
+	if((status & CapStatusValid) == 0)
+		return 0;
+
+	master = regs[ArbErrCapMaster];
+
+	addr = regs[ArbErrCapAddr];
+	addr |= (uvlong)regs[ArbErrCapAddrHi]<<32;
+
+	regs[ArbErrCapClear] = CapStatusValid;
+
+	iprint("cpu%d: GISB arbiter error: %s%s %s bus addr %llux, master %.8ux\n",
+		m->machno,
+		(status & CapStatusTimeout) ? "timeout" : "",
+		(status & CapStatusAbort) ? "abort" : "",
+		(status & CapStatusWrite) ? "writing" : "reading",
+		addr,
+		master);
+
+	return 1;
+}
+
+void
+gisblink(void)
+{
+	extern int (*buserror)(Ureg*);	// trap.c
+
+	regs[ArbErrCapClear] = CapStatusValid;
+
+	buserror = arbinterrupt;
+}

sys/src/9/bcm64/trap.c

@@ -10,6 +10,8 @@
 #include "ureg.h"
 #include "sysreg.h"
 
+int	(*buserror)(Ureg*);
+
 /* SPSR bits user can modify */
 #define USPSRMASK	(0xFULL<<28)
 
@@ -141,6 +143,8 @@ trap(Ureg *ureg)
 		}
 		if(intr == 3){
 	case 0x2F:	// SError interrupt
+			if(buserror != nil && (*buserror)(ureg))
+				break;
 			dumpregs(ureg);
 			panic("SError interrupt");
 			break;