add support for peeking at pci busses on UltraSparc systems. This prevents

data access errors when trying to read/write to non-existant PCI devices.

fix the psycho bridge to use peek for probing devices.  This no longer
fakes it if the OFW node doesn't exist (and the reg == 0).

Reviewed by:	jake, tmm

sys/sparc64/include/bus.h

@@ -811,6 +811,33 @@ bus_space_copy_region_stream_8(bus_space_tag_t t, bus_space_handle_t h1,
 	    bus_space_write_stream_8(t, h1, o1, bus_space_read_8(t, h2, o2));
 }
 
+static __inline int
+bus_space_peek_1(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o,
+	u_int8_t *a)
+{
+
+	__BUS_DEBUG_ACCESS(h, o, "peek", 1);
+	return (fasword8(bus_type_asi[t->bst_type], (caddr_t)(h + o), a));
+}
+
+static __inline int
+bus_space_peek_2(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o,
+	u_int16_t *a)
+{
+
+	__BUS_DEBUG_ACCESS(h, o, "peek", 2);
+	return (fasword16(bus_type_asi[t->bst_type], (caddr_t)(h + o), a));
+}
+
+static __inline int
+bus_space_peek_4(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o,
+	u_int32_t *a)
+{
+
+	__BUS_DEBUG_ACCESS(h, o, "peek", 4);
+	return (fasword32(bus_type_asi[t->bst_type], (caddr_t)(h + o), a));
+}
+
 /* Back-compat functions for old ISA drivers */
 extern bus_space_tag_t isa_io_bt;
 extern bus_space_handle_t isa_io_hdl;

sys/sparc64/include/cpufunc.h

@@ -136,6 +136,15 @@ STNC_GEN(u_long, stxa);
 #define	stwa(va, asi, val)	ST_GENERIC(va, asi, val, stwa)
 #define	stxa(va, asi, val)	ST_GENERIC(va, asi, val, stxa)
 
+/*
+ * Attempt to read from addr, val.  If a Data Access Error trap happens,
+ * they return -1 and the contents of val is undefined.  A return of 0
+ * means no trap happened, and the contents of val is valid.
+ */
+int fasword8(u_long asi, void *addr, uint8_t *val);
+int fasword16(u_long asi, void *addr, uint16_t *val);
+int fasword32(u_long asi, void *addr, uint32_t *val);
+
 #define	membar(mask) do {						\
 	__asm __volatile("membar %0" : : "n" (mask) : "memory");	\
 } while (0)

sys/sparc64/pci/psycho.c

@@ -57,6 +57,7 @@
 #include <machine/nexusvar.h>
 #include <machine/ofw_upa.h>
 #include <machine/resource.h>
+#include <machine/cpu.h>
 
 #include <sys/rman.h>
 
@@ -872,33 +873,39 @@ psycho_read_config(device_t dev, u_int bus, u_int slot, u_int func, u_int reg,
 	bus_space_handle_t bh;
 	u_long offset = 0;
 	u_int32_t r, devid;
+	u_int8_t byte;
+	u_int16_t shrt;
+	u_int32_t wrd;
 	int i;
 
-	/*
-	 * The psycho bridge does not tolerate accesses to unconfigured PCI
-	 * devices' or function's config space, so look up the device in the
-	 * firmware device tree first, and if it is not present, return a value
-	 * that will make the detection code think that there is no device here.
-	 * This is ugly...
-	 */
-	if (reg == 0 && ofw_pci_find_node(bus, slot, func) == 0)
-		return (0xffffffff);
 	sc = (struct psycho_softc *)device_get_softc(dev);
 	offset = PSYCHO_CONF_OFF(bus, slot, func, reg);
 	bh = sc->sc_bh[PCI_CS_CONFIG];
 	switch (width) {
 	case 1:
-		r = bus_space_read_1(sc->sc_cfgt, bh, offset);
+		i = bus_space_peek_1(sc->sc_cfgt, bh, offset, &byte);
+		r = byte;
 		break;
 	case 2:
-		r = bus_space_read_2(sc->sc_cfgt, bh, offset);
+		i = bus_space_peek_2(sc->sc_cfgt, bh, offset, &shrt);
+		r = shrt;
 		break;
 	case 4:
-		r = bus_space_read_4(sc->sc_cfgt, bh, offset);
+		i = bus_space_peek_4(sc->sc_cfgt, bh, offset, &wrd);
+		r = wrd;
 		break;
 	default:
 		panic("psycho_read_config: bad width");
 	}
+
+	if (i) {
+#ifdef PSYCHO_DEBUG
+		printf("psycho read data error reading: %d.%d.%d: 0x%x\n",
+		    bus, slot, func, reg);
+#endif
+		r = -1;
+	}
+
 	if (reg == PCIR_INTPIN && r == 0) {
 		/* Check for DQT_BAD_INTPIN quirk. */
 		devid = psycho_read_config(dev, bus, slot, func,

sys/sparc64/sparc64/support.S

@@ -527,6 +527,58 @@ ENTRY(fs_fault)
 	 mov	-1, %o0
 END(fsfault)
 
+	.globl	fas_nofault_begin
+fas_nofault_begin:
+
+/*
+ * int fasword8(u_long asi, uint64_t addr, uint8_t *val)
+ */
+ENTRY(fasword8)
+	wr	%o0, 0, %asi
+	membar	#Sync
+	lduba	[%o1] %asi, %o3
+	membar	#Sync
+	stb	%o3, [%o2]
+	retl
+	 clr	%o0
+END(fasword8)
+
+/*
+ * int fasword16(u_long asi, uint64_t addr, uint16_t *val)
+ */
+ENTRY(fasword16)
+	wr	%o0, 0, %asi
+	membar	#Sync
+	lduha	[%o1] %asi, %o3
+	membar	#Sync
+	sth	%o3, [%o2]
+	retl
+	 clr	%o0
+END(fasword16)
+
+/*
+ * int fasword32(u_long asi, uint64_t addr, uint32_t *val)
+ */
+ENTRY(fasword32)
+	wr	%o0, 0, %asi
+	membar	#Sync
+	lduwa	[%o1] %asi, %o3
+	membar	#Sync
+	stw	%o3, [%o2]
+	retl
+	 clr	%o0
+END(fasword32)
+
+	.globl	fas_nofault_end
+fas_nofault_end:
+	nop
+
+	.globl	fas_fault
+ENTRY(fas_fault)
+	retl
+	 mov	-1, %o0
+END(fas_fault)
+
 	.globl	fpu_fault_begin
 fpu_fault_begin:
 	nop

sys/sparc64/sparc64/trap.c

@@ -101,6 +101,10 @@ extern char fs_nofault_end[];
 extern char fs_nofault_intr_begin[];
 extern char fs_nofault_intr_end[];
 
+extern char fas_fault[];
+extern char fas_nofault_begin[];
+extern char fas_nofault_end[];
+
 extern char *syscallnames[];
 
 const char *trap_msg[] = {
@@ -329,6 +333,27 @@ trap(struct trapframe *tf)
 			}
 			error = 1;	
 			break;
+		case T_DATA_ERROR:
+			/*
+			 * handle PCI poke/peek as per UltraSPARC IIi
+			 * User's Manual 16.2.1.
+			 *
+			 * XXX - We really should make sure that tpc is
+			 * pointing to the membar #Sync we are expecting.
+			 */
+#define MEMBARSYNC_INST	((u_int32_t)0x8143e040)
+			if (tf->tf_tpc > (u_long)fas_nofault_begin &&
+			    tf->tf_tpc < (u_long)fas_nofault_end &&
+			    *(u_int32_t *)tf->tf_tpc == MEMBARSYNC_INST &&
+			    ((u_int32_t *)tf->tf_tpc)[-2] == MEMBARSYNC_INST) {
+				tf->tf_tpc = (u_long)fas_fault;
+				tf->tf_tnpc = tf->tf_tpc + 4;
+				error = 0;
+				break;
+			}
+#undef MEMBARSYNC_INST
+			error = 1;
+			break;
 		default:
 			error = 1;
 			break;