IB/ipath: prevent hardware from being accessed during reset

The reset code now turns off the PRESENT flag during a reset, so that
other code won't attempt to access a device that's in mid-reset.
Signed-off-by: Bryan O'Sullivan <bos@pathscale.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/ipath/ipath_intr.c

@@ -719,11 +719,24 @@ static void handle_rcv(struct ipath_devdata *dd, u32 istat)
 irqreturn_t ipath_intr(int irq, void *data, struct pt_regs *regs)
 {
 	struct ipath_devdata *dd = data;
-	u32 istat = ipath_read_kreg32(dd, dd->ipath_kregs->kr_intstatus);
+	u32 istat;
 	ipath_err_t estat = 0;
 	static unsigned unexpected = 0;
 	irqreturn_t ret;
 
+	if(!(dd->ipath_flags & IPATH_PRESENT)) {
+		/* this is mostly so we don't try to touch the chip while
+		 * it is being reset */
+		/*
+		 * This return value is perhaps odd, but we do not want the
+		 * interrupt core code to remove our interrupt handler
+		 * because we don't appear to be handling an interrupt
+		 * during a chip reset.
+		 */
+		return IRQ_HANDLED;
+	}
+
+	istat = ipath_read_kreg32(dd, dd->ipath_kregs->kr_intstatus);
 	if (unlikely(!istat)) {
 		ipath_stats.sps_nullintr++;
 		ret = IRQ_NONE; /* not our interrupt, or already handled */

drivers/infiniband/hw/ipath/ipath_kernel.h

@@ -731,7 +731,7 @@ u64 ipath_read_kreg64_port(const struct ipath_devdata *, ipath_kreg,
 static inline u32 ipath_read_ureg32(const struct ipath_devdata *dd,
 				    ipath_ureg regno, int port)
 {
-	if (!dd->ipath_kregbase)
+	if (!dd->ipath_kregbase || !(dd->ipath_flags & IPATH_PRESENT))
 		return 0;
 
 	return readl(regno + (u64 __iomem *)
@@ -762,7 +762,7 @@ static inline void ipath_write_ureg(const struct ipath_devdata *dd,
 static inline u32 ipath_read_kreg32(const struct ipath_devdata *dd,
 				    ipath_kreg regno)
 {
-	if (!dd->ipath_kregbase)
+	if (!dd->ipath_kregbase || !(dd->ipath_flags & IPATH_PRESENT))
 		return -1;
 	return readl((u32 __iomem *) & dd->ipath_kregbase[regno]);
 }
@@ -770,7 +770,7 @@ static inline u32 ipath_read_kreg32(const struct ipath_devdata *dd,
 static inline u64 ipath_read_kreg64(const struct ipath_devdata *dd,
 				    ipath_kreg regno)
 {
-	if (!dd->ipath_kregbase)
+	if (!dd->ipath_kregbase || !(dd->ipath_flags & IPATH_PRESENT))
 		return -1;
 
 	return readq(&dd->ipath_kregbase[regno]);
@@ -786,7 +786,7 @@ static inline void ipath_write_kreg(const struct ipath_devdata *dd,
 static inline u64 ipath_read_creg(const struct ipath_devdata *dd,
 				  ipath_sreg regno)
 {
-	if (!dd->ipath_kregbase)
+	if (!dd->ipath_kregbase || !(dd->ipath_flags & IPATH_PRESENT))
 		return 0;
 
 	return readq(regno + (u64 __iomem *)
@@ -797,7 +797,7 @@ static inline u64 ipath_read_creg(const struct ipath_devdata *dd,
 static inline u32 ipath_read_creg32(const struct ipath_devdata *dd,
 					 ipath_sreg regno)
 {
-	if (!dd->ipath_kregbase)
+	if (!dd->ipath_kregbase || !(dd->ipath_flags & IPATH_PRESENT))
 		return 0;
 	return readl(regno + (u64 __iomem *)
 		     (dd->ipath_cregbase +

drivers/infiniband/hw/ipath/ipath_pe800.c

@@ -972,6 +972,8 @@ static int ipath_setup_pe_reset(struct ipath_devdata *dd)
 	/* Use ERROR so it shows up in logs, etc. */
 	ipath_dev_err(dd, "Resetting PE-800 unit %u\n",
 		      dd->ipath_unit);
+	/* keep chip from being accessed in a few places */
+	dd->ipath_flags &= ~(IPATH_INITTED|IPATH_PRESENT);
 	val = dd->ipath_control | INFINIPATH_C_RESET;
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_control, val);
 	mb();
@@ -997,6 +999,8 @@ static int ipath_setup_pe_reset(struct ipath_devdata *dd)
 		if ((r = pci_enable_device(dd->pcidev)))
 			ipath_dev_err(dd, "pci_enable_device failed after "
 				      "reset: %d\n", r);
+		/* whether it worked or not, mark as present, again */
+		dd->ipath_flags |= IPATH_PRESENT;
 		val = ipath_read_kreg64(dd, dd->ipath_kregs->kr_revision);
 		if (val == dd->ipath_revision) {
 			ipath_cdbg(VERBOSE, "Got matching revision "