USB: xhci: No-op command queueing and irq handler.

xHCI host controllers can optionally implement a no-op test.  This
simple test ensures the OS has correctly setup all basic data structures
and can correctly respond to interrupts from the host controller
hardware.

There are two rings exercised by the no-op test:  the command ring, and
the event ring.

The host controller driver writes a no-op command TRB to the command
ring, and rings the doorbell for the command ring (the first entry in
the doorbell array).  The hardware receives this event, places a command
completion event on the event ring, and fires an interrupt.

The host controller driver sees the interrupt, and checks the event ring
for TRBs it can process, and sees the command completion event.  (See
the rules in xhci-ring.c for who "owns" a TRB.  This is a simplified set
of rules, and may not contain all the details that are in the xHCI 0.95
spec.)

A timer fires every 60 seconds to debug the state of the hardware and
command and event rings.  This timer only runs if
CONFIG_USB_XHCI_HCD_DEBUGGING is 'y'.
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

@@ -230,6 +230,64 @@ void xhci_print_registers(struct xhci_hcd *xhci)
 	xhci_print_op_regs(xhci);
 }
 
+void xhci_print_trb_offsets(struct xhci_hcd *xhci, union xhci_trb *trb)
+{
+	int i;
+	for (i = 0; i < 4; ++i)
+		xhci_dbg(xhci, "Offset 0x%x = 0x%x\n",
+				i*4, trb->generic.field[i]);
+}
+
+/**
+ * Debug a transfer request block (TRB).
+ */
+void xhci_debug_trb(struct xhci_hcd *xhci, union xhci_trb *trb)
+{
+	u64	address;
+	u32	type = xhci_readl(xhci, &trb->link.control) & TRB_TYPE_BITMASK;
+
+	switch (type) {
+	case TRB_TYPE(TRB_LINK):
+		xhci_dbg(xhci, "Link TRB:\n");
+		xhci_print_trb_offsets(xhci, trb);
+
+		address = trb->link.segment_ptr[0] +
+			(((u64) trb->link.segment_ptr[1]) << 32);
+		xhci_dbg(xhci, "Next ring segment DMA address = 0x%llx\n", address);
+
+		xhci_dbg(xhci, "Interrupter target = 0x%x\n",
+				GET_INTR_TARGET(trb->link.intr_target));
+		xhci_dbg(xhci, "Cycle bit = %u\n",
+				(unsigned int) (trb->link.control & TRB_CYCLE));
+		xhci_dbg(xhci, "Toggle cycle bit = %u\n",
+				(unsigned int) (trb->link.control & LINK_TOGGLE));
+		xhci_dbg(xhci, "No Snoop bit = %u\n",
+				(unsigned int) (trb->link.control & TRB_NO_SNOOP));
+		break;
+	case TRB_TYPE(TRB_TRANSFER):
+		address = trb->trans_event.buffer[0] +
+			(((u64) trb->trans_event.buffer[1]) << 32);
+		/*
+		 * FIXME: look at flags to figure out if it's an address or if
+		 * the data is directly in the buffer field.
+		 */
+		xhci_dbg(xhci, "DMA address or buffer contents= %llu\n", address);
+		break;
+	case TRB_TYPE(TRB_COMPLETION):
+		address = trb->event_cmd.cmd_trb[0] +
+			(((u64) trb->event_cmd.cmd_trb[1]) << 32);
+		xhci_dbg(xhci, "Command TRB pointer = %llu\n", address);
+		xhci_dbg(xhci, "Completion status = %u\n",
+				(unsigned int) GET_COMP_CODE(trb->event_cmd.status));
+		xhci_dbg(xhci, "Flags = 0x%x\n", (unsigned int) trb->event_cmd.flags);
+		break;
+	default:
+		xhci_dbg(xhci, "Unknown TRB with TRB type ID %u\n",
+				(unsigned int) type>>10);
+		xhci_print_trb_offsets(xhci, trb);
+		break;
+	}
+}
 
 /**
  * Debug a segment with an xHCI ring.
@@ -261,6 +319,20 @@ void xhci_debug_segment(struct xhci_hcd *xhci, struct xhci_segment *seg)
 	}
 }
 
+void xhci_dbg_ring_ptrs(struct xhci_hcd *xhci, struct xhci_ring *ring)
+{
+	xhci_dbg(xhci, "Ring deq = 0x%x (virt), 0x%x (dma)\n",
+			(unsigned int) ring->dequeue,
+			trb_virt_to_dma(ring->deq_seg, ring->dequeue));
+	xhci_dbg(xhci, "Ring deq updated %u times\n",
+			ring->deq_updates);
+	xhci_dbg(xhci, "Ring enq = 0x%x (virt), 0x%x (dma)\n",
+			(unsigned int) ring->enqueue,
+			trb_virt_to_dma(ring->enq_seg, ring->enqueue));
+	xhci_dbg(xhci, "Ring enq updated %u times\n",
+			ring->enq_updates);
+}
+
 /**
  * Debugging for an xHCI ring, which is a queue broken into multiple segments.
  *
@@ -277,6 +349,10 @@ void xhci_debug_ring(struct xhci_hcd *xhci, struct xhci_ring *ring)
 	struct xhci_segment *first_seg = ring->first_seg;
 	xhci_debug_segment(xhci, first_seg);
 
+	if (!ring->enq_updates && !ring->deq_updates) {
+		xhci_dbg(xhci, "  Ring has not been updated\n");
+		return;
+	}
 	for (seg = first_seg->next; seg != first_seg; seg = seg->next)
 		xhci_debug_segment(xhci, seg);
 }

drivers/usb/host/xhci-hcd.c

@@ -217,6 +217,120 @@ int xhci_init(struct usb_hcd *hcd)
 	return retval;
 }
 
+/*
+ * Called in interrupt context when there might be work
+ * queued on the event ring
+ *
+ * xhci->lock must be held by caller.
+ */
+static void xhci_work(struct xhci_hcd *xhci)
+{
+	u32 temp;
+
+	/*
+	 * Clear the op reg interrupt status first,
+	 * so we can receive interrupts from other MSI-X interrupters.
+	 * Write 1 to clear the interrupt status.
+	 */
+	temp = xhci_readl(xhci, &xhci->op_regs->status);
+	temp |= STS_EINT;
+	xhci_writel(xhci, temp, &xhci->op_regs->status);
+	/* FIXME when MSI-X is supported and there are multiple vectors */
+	/* Clear the MSI-X event interrupt status */
+
+	/* Acknowledge the interrupt */
+	temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
+	temp |= 0x3;
+	xhci_writel(xhci, temp, &xhci->ir_set->irq_pending);
+	/* Flush posted writes */
+	xhci_readl(xhci, &xhci->ir_set->irq_pending);
+
+	/* FIXME this should be a delayed service routine that clears the EHB */
+	handle_event(xhci);
+
+	/* Clear the event handler busy flag; the event ring should be empty. */
+	temp = xhci_readl(xhci, &xhci->ir_set->erst_dequeue[0]);
+	xhci_writel(xhci, temp & ~ERST_EHB, &xhci->ir_set->erst_dequeue[0]);
+	/* Flush posted writes -- FIXME is this necessary? */
+	xhci_readl(xhci, &xhci->ir_set->irq_pending);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * xHCI spec says we can get an interrupt, and if the HC has an error condition,
+ * we might get bad data out of the event ring.  Section 4.10.2.7 has a list of
+ * indicators of an event TRB error, but we check the status *first* to be safe.
+ */
+irqreturn_t xhci_irq(struct usb_hcd *hcd)
+{
+	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
+	u32 temp, temp2;
+
+	spin_lock(&xhci->lock);
+	/* Check if the xHC generated the interrupt, or the irq is shared */
+	temp = xhci_readl(xhci, &xhci->op_regs->status);
+	temp2 = xhci_readl(xhci, &xhci->ir_set->irq_pending);
+	if (!(temp & STS_EINT) && !ER_IRQ_PENDING(temp2)) {
+		spin_unlock(&xhci->lock);
+		return IRQ_NONE;
+	}
+
+	temp = xhci_readl(xhci, &xhci->op_regs->status);
+	if (temp & STS_FATAL) {
+		xhci_warn(xhci, "WARNING: Host System Error\n");
+		xhci_halt(xhci);
+		xhci_to_hcd(xhci)->state = HC_STATE_HALT;
+		return -ESHUTDOWN;
+	}
+
+	xhci_work(xhci);
+	spin_unlock(&xhci->lock);
+
+	return IRQ_HANDLED;
+}
+
+#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
+void event_ring_work(unsigned long arg)
+{
+	unsigned long flags;
+	int temp;
+	struct xhci_hcd *xhci = (struct xhci_hcd *) arg;
+	int i, j;
+
+	xhci_dbg(xhci, "Poll event ring: %lu\n", jiffies);
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	temp = xhci_readl(xhci, &xhci->op_regs->status);
+	xhci_dbg(xhci, "op reg status = 0x%x\n", temp);
+	temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
+	xhci_dbg(xhci, "ir_set 0 pending = 0x%x\n", temp);
+	xhci_dbg(xhci, "No-op commands handled = %d\n", xhci->noops_handled);
+	xhci_dbg(xhci, "HC error bitmask = 0x%x\n", xhci->error_bitmask);
+	xhci->error_bitmask = 0;
+	xhci_dbg(xhci, "Event ring:\n");
+	xhci_debug_segment(xhci, xhci->event_ring->deq_seg);
+	xhci_dbg_ring_ptrs(xhci, xhci->event_ring);
+	temp = xhci_readl(xhci, &xhci->ir_set->erst_dequeue[0]);
+	temp &= ERST_PTR_MASK;
+	xhci_dbg(xhci, "ERST deq = 0x%x\n", temp);
+	xhci_dbg(xhci, "Command ring:\n");
+	xhci_debug_segment(xhci, xhci->cmd_ring->deq_seg);
+	xhci_dbg_ring_ptrs(xhci, xhci->cmd_ring);
+	xhci_dbg_cmd_ptrs(xhci);
+
+	if (xhci->noops_submitted != NUM_TEST_NOOPS)
+		if (setup_one_noop(xhci))
+			ring_cmd_db(xhci);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	if (!xhci->zombie)
+		mod_timer(&xhci->event_ring_timer, jiffies + POLL_TIMEOUT * HZ);
+	else
+		xhci_dbg(xhci, "Quit polling the event ring.\n");
+}
+#endif
+
 /*
  * Start the HC after it was halted.
  *
@@ -233,8 +347,9 @@ int xhci_run(struct usb_hcd *hcd)
 {
 	u32 temp;
 	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
-	xhci_dbg(xhci, "xhci_run\n");
+	void (*doorbell)(struct xhci_hcd *) = NULL;
 
+	xhci_dbg(xhci, "xhci_run\n");
 #if 0	/* FIXME: MSI not setup yet */
 	/* Do this at the very last minute */
 	ret = xhci_setup_msix(xhci);
@@ -243,6 +358,17 @@ int xhci_run(struct usb_hcd *hcd)
 
 	return -ENOSYS;
 #endif
+#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
+	init_timer(&xhci->event_ring_timer);
+	xhci->event_ring_timer.data = (unsigned long) xhci;
+	xhci->event_ring_timer.function = event_ring_work;
+	/* Poll the event ring */
+	xhci->event_ring_timer.expires = jiffies + POLL_TIMEOUT * HZ;
+	xhci->zombie = 0;
+	xhci_dbg(xhci, "Setting event ring polling timer\n");
+	add_timer(&xhci->event_ring_timer);
+#endif
+
 	xhci_dbg(xhci, "// Set the interrupt modulation register\n");
 	temp = xhci_readl(xhci, &xhci->ir_set->irq_control);
 	temp &= 0xffff;
@@ -266,10 +392,24 @@ int xhci_run(struct usb_hcd *hcd)
 			&xhci->ir_set->irq_pending);
 	xhci_print_ir_set(xhci, xhci->ir_set, 0);
 
+	if (NUM_TEST_NOOPS > 0)
+		doorbell = setup_one_noop(xhci);
+
 	xhci_dbg(xhci, "Command ring memory map follows:\n");
 	xhci_debug_ring(xhci, xhci->cmd_ring);
+	xhci_dbg_ring_ptrs(xhci, xhci->cmd_ring);
+	xhci_dbg_cmd_ptrs(xhci);
+
 	xhci_dbg(xhci, "ERST memory map follows:\n");
 	xhci_dbg_erst(xhci, &xhci->erst);
+	xhci_dbg(xhci, "Event ring:\n");
+	xhci_debug_ring(xhci, xhci->event_ring);
+	xhci_dbg_ring_ptrs(xhci, xhci->event_ring);
+	temp = xhci_readl(xhci, &xhci->ir_set->erst_dequeue[1]);
+	xhci_dbg(xhci, "ERST deq upper = 0x%x\n", temp);
+	temp = xhci_readl(xhci, &xhci->ir_set->erst_dequeue[0]);
+	temp &= ERST_PTR_MASK;
+	xhci_dbg(xhci, "ERST deq = 0x%x\n", temp);
 
 	temp = xhci_readl(xhci, &xhci->op_regs->command);
 	temp |= (CMD_RUN);
@@ -280,6 +420,8 @@ int xhci_run(struct usb_hcd *hcd)
 	temp = xhci_readl(xhci, &xhci->op_regs->command);
 	xhci_dbg(xhci, "// @%x = 0x%x\n",
 			(unsigned int) &xhci->op_regs->command, temp);
+	if (doorbell)
+		(*doorbell)(xhci);
 
 	xhci_dbg(xhci, "Finished xhci_run\n");
 	return 0;
@@ -309,6 +451,12 @@ void xhci_stop(struct usb_hcd *hcd)
 #if 0	/* No MSI yet */
 	xhci_cleanup_msix(xhci);
 #endif
+#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
+	/* Tell the event ring poll function not to reschedule */
+	xhci->zombie = 1;
+	del_timer_sync(&xhci->event_ring_timer);
+#endif
+
 	xhci_dbg(xhci, "// Disabling event ring interrupts\n");
 	temp = xhci_readl(xhci, &xhci->op_regs->status);
 	xhci_writel(xhci, temp & ~STS_EINT, &xhci->op_regs->status);
@@ -346,6 +494,8 @@ void xhci_shutdown(struct usb_hcd *hcd)
 		    xhci_readl(xhci, &xhci->op_regs->status));
 }
 
+/*-------------------------------------------------------------------------*/
+
 int xhci_get_frame(struct usb_hcd *hcd)
 {
 	struct xhci_hcd *xhci = hcd_to_xhci(hcd);

drivers/usb/host/xhci-mem.c

@@ -172,7 +172,9 @@ static struct xhci_ring *xhci_ring_alloc(struct xhci_hcd *xhci,
 	}
 	/* The ring is empty, so the enqueue pointer == dequeue pointer */
 	ring->enqueue = ring->first_seg->trbs;
+	ring->enq_seg = ring->first_seg;
 	ring->dequeue = ring->enqueue;
+	ring->deq_seg = ring->first_seg;
 	/* The ring is initialized to 0. The producer must write 1 to the cycle
 	 * bit to handover ownership of the TRB, so PCS = 1.  The consumer must
 	 * compare CCS to the cycle bit to check ownership, so CCS = 1.
@@ -374,14 +376,7 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 	xhci_writel(xhci, val, &xhci->ir_set->erst_base[0]);
 
 	/* Set the event ring dequeue address */
-	xhci_dbg(xhci, "// Set ERST dequeue address for ir_set 0 = 0x%x%x\n",
-			xhci->erst.entries[0].seg_addr[1], xhci->erst.entries[0].seg_addr[0]);
-	val = xhci_readl(xhci, &xhci->run_regs->ir_set[0].erst_dequeue[0]);
-	val &= ERST_PTR_MASK;
-	val |= (xhci->erst.entries[0].seg_addr[0] & ~ERST_PTR_MASK);
-	xhci_writel(xhci, val, &xhci->run_regs->ir_set[0].erst_dequeue[0]);
-	xhci_writel(xhci, xhci->erst.entries[0].seg_addr[1],
-			&xhci->run_regs->ir_set[0].erst_dequeue[1]);
+	set_hc_event_deq(xhci);
 	xhci_dbg(xhci, "Wrote ERST address to ir_set 0.\n");
 	xhci_print_ir_set(xhci, xhci->ir_set, 0);
 

drivers/usb/host/xhci-pci.c

@@ -96,6 +96,7 @@ static const struct hc_driver xhci_pci_hc_driver = {
 	/*
 	 * generic hardware linkage
 	 */
+	.irq =			xhci_irq,
 	.flags =		HCD_MEMORY | HCD_USB3,
 
 	/*

drivers/usb/host/xhci.h

@@ -24,6 +24,7 @@
 #define __LINUX_XHCI_HCD_H
 
 #include <linux/usb.h>
+#include <linux/timer.h>
 
 #include "../core/hcd.h"
 /* Code sharing between pci-quirks and xhci hcd */
@@ -377,6 +378,7 @@ struct intr_reg {
 /* irq_pending bitmasks */
 #define	ER_IRQ_PENDING(p)	((p) & 0x1)
 /* bits 2:31 need to be preserved */
+/* THIS IS BUGGY - FIXME - IP IS WRITE 1 TO CLEAR */
 #define	ER_IRQ_CLEAR(p)		((p) & 0xfffffffe)
 #define	ER_IRQ_ENABLE(p)	((ER_IRQ_CLEAR(p)) | 0x2)
 #define	ER_IRQ_DISABLE(p)	((ER_IRQ_CLEAR(p)) & ~(0x2))
@@ -699,11 +701,14 @@ struct xhci_link_trb {
 /* control bitfields */
 #define LINK_TOGGLE	(0x1<<1)
 
+/* Command completion event TRB */
+struct xhci_event_cmd {
+	/* Pointer to command TRB, or the value passed by the event data trb */
+	u32 cmd_trb[2];
+	u32 status;
+	u32 flags;
+} __attribute__ ((packed));
 
-union xhci_trb {
-	struct xhci_link_trb		link;
-	struct xhci_transfer_event	trans_event;
-};
 
 /* Normal TRB fields */
 /* transfer_len bitmasks - bits 0:16 */
@@ -737,6 +742,17 @@ union xhci_trb {
 /* Control transfer TRB specific fields */
 #define TRB_DIR_IN		(1<<16)
 
+struct xhci_generic_trb {
+	u32 field[4];
+} __attribute__ ((packed));
+
+union xhci_trb {
+	struct xhci_link_trb		link;
+	struct xhci_transfer_event	trans_event;
+	struct xhci_event_cmd		event_cmd;
+	struct xhci_generic_trb		generic;
+};
+
 /* TRB bit mask */
 #define	TRB_TYPE_BITMASK	(0xfc00)
 #define TRB_TYPE(p)		((p) << 10)
@@ -825,7 +841,11 @@ struct xhci_segment {
 struct xhci_ring {
 	struct xhci_segment	*first_seg;
 	union  xhci_trb		*enqueue;
+	struct xhci_segment	*enq_seg;
+	unsigned int		enq_updates;
 	union  xhci_trb		*dequeue;
+	struct xhci_segment	*deq_seg;
+	unsigned int		deq_updates;
 	/*
 	 * Write the cycle state into the TRB cycle field to give ownership of
 	 * the TRB to the host controller (if we are the producer), or to check
@@ -861,6 +881,8 @@ struct xhci_erst {
 #define	ERST_SIZE	64
 /* Initial number of event segment rings allocated */
 #define	ERST_ENTRIES	1
+/* Poll every 60 seconds */
+#define	POLL_TIMEOUT	60
 /* XXX: Make these module parameters */
 
 
@@ -907,8 +929,21 @@ struct xhci_hcd {
 	/* DMA pools */
 	struct dma_pool	*device_pool;
 	struct dma_pool	*segment_pool;
+
+#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
+	/* Poll the rings - for debugging */
+	struct timer_list	event_ring_timer;
+	int			zombie;
+#endif
+	/* Statistics */
+	int			noops_submitted;
+	int			noops_handled;
+	int			error_bitmask;
 };
 
+/* For testing purposes */
+#define NUM_TEST_NOOPS	0
+
 /* convert between an HCD pointer and the corresponding EHCI_HCD */
 static inline struct xhci_hcd *hcd_to_xhci(struct usb_hcd *hcd)
 {
@@ -956,9 +991,11 @@ void xhci_print_ir_set(struct xhci_hcd *xhci, struct intr_reg *ir_set, int set_n
 void xhci_print_registers(struct xhci_hcd *xhci);
 void xhci_dbg_regs(struct xhci_hcd *xhci);
 void xhci_print_run_regs(struct xhci_hcd *xhci);
+void xhci_debug_segment(struct xhci_hcd *xhci, struct xhci_segment *seg);
 void xhci_debug_ring(struct xhci_hcd *xhci, struct xhci_ring *ring);
 void xhci_dbg_erst(struct xhci_hcd *xhci, struct xhci_erst *erst);
 void xhci_dbg_cmd_ptrs(struct xhci_hcd *xhci);
+void xhci_dbg_ring_ptrs(struct xhci_hcd *xhci, struct xhci_ring *ring);
 
 /* xHCI memory managment */
 void xhci_mem_cleanup(struct xhci_hcd *xhci);
@@ -978,5 +1015,13 @@ int xhci_run(struct usb_hcd *hcd);
 void xhci_stop(struct usb_hcd *hcd);
 void xhci_shutdown(struct usb_hcd *hcd);
 int xhci_get_frame(struct usb_hcd *hcd);
+irqreturn_t xhci_irq(struct usb_hcd *hcd);
+
+/* xHCI ring, segment, TRB, and TD functions */
+dma_addr_t trb_virt_to_dma(struct xhci_segment *seg, union xhci_trb *trb);
+void ring_cmd_db(struct xhci_hcd *xhci);
+void *setup_one_noop(struct xhci_hcd *xhci);
+void handle_event(struct xhci_hcd *xhci);
+void set_hc_event_deq(struct xhci_hcd *xhci);
 
 #endif /* __LINUX_XHCI_HCD_H */