USB: xhci: Ring allocation and initialization.

Allocate basic xHCI host controller data structures.  For every xHC, there
is a command ring, an event ring, and a doorbell array.

The doorbell array is used to notify the host controller that work has
been enqueued onto one of the rings.  The host controller driver enqueues
commands on the command ring.  The HW enqueues command completion events
on the event ring and interrupts the system (currently using PCI
interrupts, although the xHCI HW will use MSI interrupts eventually).

All rings and the doorbell array must be allocated by the xHCI host
controller driver.

Each ring is comprised of one or more segments, which consists of 16-byte
Transfer Request Blocks (TRBs) that can be chained to form a Transfer
Descriptor (TD) that represents a multiple-buffer request.  Segments are
linked into a ring using Link TRBs, which means they are dynamically
growable.

The producer of the ring enqueues a TD by writing one or more TRBs in the
ring and toggling the TRB cycle bit for each TRB.  The consumer knows it
can process the TRB when the cycle bit matches its internal consumer cycle
state for the ring.  The consumer cycle state is toggled an odd amount of
times in the ring.

An example ring (a ring must have a minimum of 16 TRBs on it, but that's
too big to draw in ASCII art):

              chain  cycle
               bit    bit
 ------------------------
| TD A TRB 1 |  1  |  1  |<-------------  <-- consumer dequeue ptr
 ------------------------               |     consumer cycle state = 1
| TD A TRB 2 |  1  |  1  |              |
 ------------------------               |
| TD A TRB 3 |  0  |  1  |  segment 1   |
 ------------------------               |
| TD B TRB 1 |  1  |  1  |              |
 ------------------------               |
| TD B TRB 2 |  0  |  1  |              |
 ------------------------               |
| Link TRB   |  0  |  1  |-----         |
 ------------------------     |         |
                              |         |
              chain  cycle    |         |
               bit    bit     |         |
 ------------------------     |         |
| TD C TRB 1 |  0  |  1  |<----         |
 ------------------------               |
| TD D TRB 1 |  1  |  1  |              |
 ------------------------               |
| TD D TRB 2 |  1  |  1  |   segment 2  |
 ------------------------               |
| TD D TRB 3 |  1  |  1  |              |
 ------------------------               |
| TD D TRB 4 |  1  |  1  |              |
 ------------------------               |
| Link TRB   |  1  |  1  |-----         |
 ------------------------     |         |
                              |         |
              chain  cycle    |         |
               bit    bit     |         |
 ------------------------     |         |
| TD D TRB 5 |  1  |  1  |<----         |
 ------------------------               |
| TD D TRB 6 |  0  |  1  |              |
 ------------------------               |
| TD E TRB 1 |  0  |  1  |   segment 3  |
 ------------------------               |
|            |  0  |  0  |              | <-- producer enqueue ptr
 ------------------------               |
|            |  0  |  0  |              |
 ------------------------               |
| Link TRB   |  0  |  0  |---------------
 ------------------------
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/xhci-dbg.c

@@ -56,6 +56,8 @@ void xhci_dbg_regs(struct xhci_hcd *xhci)
 	temp = xhci_readl(xhci, &xhci->cap_regs->db_off);
 	xhci_dbg(xhci, "// @%x = 0x%x DBOFF\n",
 			(unsigned int) &xhci->cap_regs->db_off, temp);
+	xhci_dbg(xhci, "// Doorbell array at 0x%x:\n",
+			(unsigned int) xhci->dba);
 }
 
 void xhci_print_cap_regs(struct xhci_hcd *xhci)
@@ -227,3 +229,82 @@ void xhci_print_registers(struct xhci_hcd *xhci)
 	xhci_print_cap_regs(xhci);
 	xhci_print_op_regs(xhci);
 }
+
+
+/**
+ * Debug a segment with an xHCI ring.
+ *
+ * @return The Link TRB of the segment, or NULL if there is no Link TRB
+ * (which is a bug, since all segments must have a Link TRB).
+ *
+ * Prints out all TRBs in the segment, even those after the Link TRB.
+ *
+ * XXX: should we print out TRBs that the HC owns?  As long as we don't
+ * write, that should be fine...  We shouldn't expect that the memory pointed to
+ * by the TRB is valid at all.  Do we care about ones the HC owns?  Probably,
+ * for HC debugging.
+ */
+void xhci_debug_segment(struct xhci_hcd *xhci, struct xhci_segment *seg)
+{
+	int i;
+	u32 addr = (u32) seg->dma;
+	union xhci_trb *trb = seg->trbs;
+
+	for (i = 0; i < TRBS_PER_SEGMENT; ++i) {
+		trb = &seg->trbs[i];
+		xhci_dbg(xhci, "@%08x %08x %08x %08x %08x\n", addr,
+				(unsigned int) trb->link.segment_ptr[0],
+				(unsigned int) trb->link.segment_ptr[1],
+				(unsigned int) trb->link.intr_target,
+				(unsigned int) trb->link.control);
+		addr += sizeof(*trb);
+	}
+}
+
+/**
+ * Debugging for an xHCI ring, which is a queue broken into multiple segments.
+ *
+ * Print out each segment in the ring.  Check that the DMA address in
+ * each link segment actually matches the segment's stored DMA address.
+ * Check that the link end bit is only set at the end of the ring.
+ * Check that the dequeue and enqueue pointers point to real data in this ring
+ * (not some other ring).
+ */
+void xhci_debug_ring(struct xhci_hcd *xhci, struct xhci_ring *ring)
+{
+	/* FIXME: Throw an error if any segment doesn't have a Link TRB */
+	struct xhci_segment *seg;
+	struct xhci_segment *first_seg = ring->first_seg;
+	xhci_debug_segment(xhci, first_seg);
+
+	for (seg = first_seg->next; seg != first_seg; seg = seg->next)
+		xhci_debug_segment(xhci, seg);
+}
+
+void xhci_dbg_erst(struct xhci_hcd *xhci, struct xhci_erst *erst)
+{
+	u32 addr = (u32) erst->erst_dma_addr;
+	int i;
+	struct xhci_erst_entry *entry;
+
+	for (i = 0; i < erst->num_entries; ++i) {
+		entry = &erst->entries[i];
+		xhci_dbg(xhci, "@%08x %08x %08x %08x %08x\n",
+				(unsigned int) addr,
+				(unsigned int) entry->seg_addr[0],
+				(unsigned int) entry->seg_addr[1],
+				(unsigned int) entry->seg_size,
+				(unsigned int) entry->rsvd);
+		addr += sizeof(*entry);
+	}
+}
+
+void xhci_dbg_cmd_ptrs(struct xhci_hcd *xhci)
+{
+	u32 val;
+
+	val = xhci_readl(xhci, &xhci->op_regs->cmd_ring[0]);
+	xhci_dbg(xhci, "// xHC command ring deq ptr low bits + flags = 0x%x\n", val);
+	val = xhci_readl(xhci, &xhci->op_regs->cmd_ring[1]);
+	xhci_dbg(xhci, "// xHC command ring deq ptr high bits = 0x%x\n", val);
+}

drivers/usb/host/xhci-hcd.c

@@ -266,6 +266,11 @@ int xhci_run(struct usb_hcd *hcd)
 			&xhci->ir_set->irq_pending);
 	xhci_print_ir_set(xhci, xhci->ir_set, 0);
 
+	xhci_dbg(xhci, "Command ring memory map follows:\n");
+	xhci_debug_ring(xhci, xhci->cmd_ring);
+	xhci_dbg(xhci, "ERST memory map follows:\n");
+	xhci_dbg_erst(xhci, &xhci->erst);
+
 	temp = xhci_readl(xhci, &xhci->op_regs->command);
 	temp |= (CMD_RUN);
 	xhci_dbg(xhci, "// Turn on HC, cmd = 0x%x.\n",