xhci: Refactor interrupter code for initial multi interrupter support.

xHC supports several interrupters, each with its own mmio register set,
event ring and MSI/MSI-X vector. Transfers can be assigned different
interrupters when queued. See xhci 4.17 for details.
Current driver only supports one interrupter.

Create a xhci_interrupter structure containing an event ring, pointer to
mmio registers for this interrupter, variables to store registers over s3
suspend, erst, etc. Add functions to create and free an interrupter, and
pass an interrupter pointer to functions that deal with events.

Secondary interrupters are also useful without having an interrupt vector.
One use case is the xHCI audio sideband offloading where a DSP can take
care of specific audio endpoints.

When all transfer events of an offloaded endpoint can be mapped to a
separate interrupter event ring the DSP can poll this ring, and we can mask
these events preventing waking up the CPU.

Only minor functional changes such as clearing some of the interrupter
registers when freeing the interrupter.

Still create only one primary interrupter.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20230202150505.618915-4-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: matnyman

drivers/usb/host/xhci-debugfs.c

@@ -692,7 +692,7 @@ void xhci_debugfs_init(struct xhci_hcd *xhci)
 				     "command-ring",
 				     xhci->debugfs_root);
 
-	xhci_debugfs_create_ring_dir(xhci, &xhci->event_ring,
+	xhci_debugfs_create_ring_dir(xhci, &xhci->interrupter->event_ring,
 				     "event-ring",
 				     xhci->debugfs_root);
 

drivers/usb/host/xhci-mem.c

@@ -1819,17 +1819,43 @@ int xhci_alloc_erst(struct xhci_hcd *xhci,
 	return 0;
 }
 
-void xhci_free_erst(struct xhci_hcd *xhci, struct xhci_erst *erst)
+static void
+xhci_free_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 {
-	size_t size;
 	struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
+	size_t erst_size;
+	u64 tmp64;
+	u32 tmp;
 
-	size = sizeof(struct xhci_erst_entry) * (erst->num_entries);
-	if (erst->entries)
-		dma_free_coherent(dev, size,
-				erst->entries,
-				erst->erst_dma_addr);
-	erst->entries = NULL;
+	if (!ir)
+		return;
+
+	erst_size = sizeof(struct xhci_erst_entry) * (ir->erst.num_entries);
+	if (ir->erst.entries)
+		dma_free_coherent(dev, erst_size,
+				  ir->erst.entries,
+				  ir->erst.erst_dma_addr);
+	ir->erst.entries = NULL;
+
+	/*
+	 * Clean out interrupter registers except ERSTBA. Clearing either the
+	 * low or high 32 bits of ERSTBA immediately causes the controller to
+	 * dereference the partially cleared 64 bit address, causing IOMMU error.
+	 */
+	tmp = readl(&ir->ir_set->erst_size);
+	tmp &= ERST_SIZE_MASK;
+	writel(tmp, &ir->ir_set->erst_size);
+
+	tmp64 = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
+	tmp64 &= (u64) ERST_PTR_MASK;
+	xhci_write_64(xhci, tmp64, &ir->ir_set->erst_dequeue);
+
+	/* free interrrupter event ring */
+	if (ir->event_ring)
+		xhci_ring_free(xhci, ir->event_ring);
+	ir->event_ring = NULL;
+
+	kfree(ir);
 }
 
 void xhci_mem_cleanup(struct xhci_hcd *xhci)
@@ -1839,12 +1865,9 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 
 	cancel_delayed_work_sync(&xhci->cmd_timer);
 
-	xhci_free_erst(xhci, &xhci->erst);
-
-	if (xhci->event_ring)
-		xhci_ring_free(xhci, xhci->event_ring);
-	xhci->event_ring = NULL;
-	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Freed event ring");
+	xhci_free_interrupter(xhci, xhci->interrupter);
+	xhci->interrupter = NULL;
+	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Freed primary event ring");
 
 	if (xhci->cmd_ring)
 		xhci_ring_free(xhci, xhci->cmd_ring);
@@ -1929,18 +1952,18 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 	xhci->usb3_rhub.bus_state.bus_suspended = 0;
 }
 
-static void xhci_set_hc_event_deq(struct xhci_hcd *xhci)
+static void xhci_set_hc_event_deq(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 {
 	u64 temp;
 	dma_addr_t deq;
 
-	deq = xhci_trb_virt_to_dma(xhci->event_ring->deq_seg,
-			xhci->event_ring->dequeue);
+	deq = xhci_trb_virt_to_dma(ir->event_ring->deq_seg,
+			ir->event_ring->dequeue);
 	if (!deq)
 		xhci_warn(xhci, "WARN something wrong with SW event ring "
 				"dequeue ptr.\n");
 	/* Update HC event ring dequeue pointer */
-	temp = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
+	temp = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
 	temp &= ERST_PTR_MASK;
 	/* Don't clear the EHB bit (which is RW1C) because
 	 * there might be more events to service.
@@ -1950,7 +1973,7 @@ static void xhci_set_hc_event_deq(struct xhci_hcd *xhci)
 			"// Write event ring dequeue pointer, "
 			"preserving EHB bit");
 	xhci_write_64(xhci, ((u64) deq & (u64) ~ERST_PTR_MASK) | temp,
-			&xhci->ir_set->erst_dequeue);
+			&ir->ir_set->erst_dequeue);
 }
 
 static void xhci_add_in_port(struct xhci_hcd *xhci, unsigned int num_ports,
@@ -2217,14 +2240,76 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags)
 	return 0;
 }
 
+static struct xhci_interrupter *
+xhci_alloc_interrupter(struct xhci_hcd *xhci, unsigned int intr_num, gfp_t flags)
+{
+	struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
+	struct xhci_interrupter *ir;
+	u64 erst_base;
+	u32 erst_size;
+	int ret;
+
+	if (intr_num > xhci->max_interrupters) {
+		xhci_warn(xhci, "Can't allocate interrupter %d, max interrupters %d\n",
+			  intr_num, xhci->max_interrupters);
+		return NULL;
+	}
+
+	if (xhci->interrupter) {
+		xhci_warn(xhci, "Can't allocate already set up interrupter %d\n", intr_num);
+		return NULL;
+	}
+
+	ir = kzalloc_node(sizeof(*ir), flags, dev_to_node(dev));
+	if (!ir)
+		return NULL;
+
+	ir->ir_set = &xhci->run_regs->ir_set[intr_num];
+	ir->event_ring = xhci_ring_alloc(xhci, ERST_NUM_SEGS, 1, TYPE_EVENT,
+					0, flags);
+	if (!ir->event_ring) {
+		xhci_warn(xhci, "Failed to allocate interrupter %d event ring\n", intr_num);
+		goto fail_ir;
+	}
+
+	ret = xhci_alloc_erst(xhci, ir->event_ring, &ir->erst, flags);
+	if (ret) {
+		xhci_warn(xhci, "Failed to allocate interrupter %d erst\n", intr_num);
+		goto fail_ev;
+
+	}
+	/* set ERST count with the number of entries in the segment table */
+	erst_size = readl(&ir->ir_set->erst_size);
+	erst_size &= ERST_SIZE_MASK;
+	erst_size |= ERST_NUM_SEGS;
+	writel(erst_size, &ir->ir_set->erst_size);
+
+	erst_base = xhci_read_64(xhci, &ir->ir_set->erst_base);
+	erst_base &= ERST_PTR_MASK;
+	erst_base |= (ir->erst.erst_dma_addr & (u64) ~ERST_PTR_MASK);
+	xhci_write_64(xhci, erst_base, &ir->ir_set->erst_base);
+
+	/* Set the event ring dequeue address of this interrupter */
+	xhci_set_hc_event_deq(xhci, ir);
+
+	return ir;
+
+fail_ev:
+	xhci_ring_free(xhci, ir->event_ring);
+fail_ir:
+	kfree(ir);
+
+	return NULL;
+}
+
 int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 {
 	dma_addr_t	dma;
 	struct device	*dev = xhci_to_hcd(xhci)->self.sysdev;
 	unsigned int	val, val2;
 	u64		val_64;
 	u32		page_size, temp;
-	int		i, ret;
+	int		i;
 
 	INIT_LIST_HEAD(&xhci->cmd_list);
 
@@ -2337,46 +2422,13 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 			" from cap regs base addr", val);
 	xhci->dba = (void __iomem *) xhci->cap_regs + val;
 	/* Set ir_set to interrupt register set 0 */
-	xhci->ir_set = &xhci->run_regs->ir_set[0];
-
-	/*
-	 * Event ring setup: Allocate a normal ring, but also setup
-	 * the event ring segment table (ERST).  Section 4.9.3.
-	 */
-	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "// Allocating event ring");
-	xhci->event_ring = xhci_ring_alloc(xhci, ERST_NUM_SEGS, 1, TYPE_EVENT,
-					0, flags);
-	if (!xhci->event_ring)
-		goto fail;
-
-	ret = xhci_alloc_erst(xhci, xhci->event_ring, &xhci->erst, flags);
-	if (ret)
-		goto fail;
-
-	/* set ERST count with the number of entries in the segment table */
-	val = readl(&xhci->ir_set->erst_size);
-	val &= ERST_SIZE_MASK;
-	val |= ERST_NUM_SEGS;
-	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
-			"// Write ERST size = %i to ir_set 0 (some bits preserved)",
-			val);
-	writel(val, &xhci->ir_set->erst_size);
 
+	/* allocate and set up primary interrupter with an event ring. */
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
-			"// Set ERST entries to point to event ring.");
-	/* set the segment table base address */
-	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
-			"// Set ERST base address for ir_set 0 = 0x%llx",
-			(unsigned long long)xhci->erst.erst_dma_addr);
-	val_64 = xhci_read_64(xhci, &xhci->ir_set->erst_base);
-	val_64 &= ERST_BASE_RSVDP;
-	val_64 |= (xhci->erst.erst_dma_addr & (u64) ~ERST_BASE_RSVDP);
-	xhci_write_64(xhci, val_64, &xhci->ir_set->erst_base);
-
-	/* Set the event ring dequeue address */
-	xhci_set_hc_event_deq(xhci);
-	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
-			"Wrote ERST address to ir_set 0.");
+		       "Allocating primary event ring");
+	xhci->interrupter = xhci_alloc_interrupter(xhci, 0, flags);
+	if (!xhci->interrupter)
+		goto fail;
 
 	xhci->isoc_bei_interval = AVOID_BEI_INTERVAL_MAX;