usb: host: xhci-mem: Allow for interrupter clients to choose specific index

Some clients may operate only on a specific XHCI interrupter instance.
Allow for the associated class driver to request for the interrupter that
it requires.

Tested-by: Puma Hsu <pumahsu@google.com>
Tested-by: Daehwan Jung <dh10.jung@samsung.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20250409194804.3773260-4-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Wesley Cheng

drivers/usb/host/xhci-mem.c

@@ -2331,30 +2331,34 @@ xhci_add_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
 
 struct xhci_interrupter *
 xhci_create_secondary_interrupter(struct usb_hcd *hcd, unsigned int segs,
-				  u32 imod_interval)
+				  u32 imod_interval, unsigned int intr_num)
 {
 	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
 	struct xhci_interrupter *ir;
 	unsigned int i;
 	int err = -ENOSPC;
 
-	if (!xhci->interrupters || xhci->max_interrupters <= 1)
+	if (!xhci->interrupters || xhci->max_interrupters <= 1 ||
+	    intr_num >= xhci->max_interrupters)
 		return NULL;
 
 	ir = xhci_alloc_interrupter(xhci, segs, GFP_KERNEL);
 	if (!ir)
 		return NULL;
 
 	spin_lock_irq(&xhci->lock);
-
-	/* Find available secondary interrupter, interrupter 0 is reserved for primary */
-	for (i = 1; i < xhci->max_interrupters; i++) {
-		if (xhci->interrupters[i] == NULL) {
-			err = xhci_add_interrupter(xhci, ir, i);
-			break;
+	if (!intr_num) {
+		/* Find available secondary interrupter, interrupter 0 is reserved for primary */
+		for (i = 1; i < xhci->max_interrupters; i++) {
+			if (!xhci->interrupters[i]) {
+				err = xhci_add_interrupter(xhci, ir, i);
+				break;
+			}
 		}
+	} else {
+		if (!xhci->interrupters[intr_num])
+			err = xhci_add_interrupter(xhci, ir, intr_num);
 	}
-
 	spin_unlock_irq(&xhci->lock);
 
 	if (err) {
@@ -2370,7 +2374,7 @@ xhci_create_secondary_interrupter(struct usb_hcd *hcd, unsigned int segs,
 			  i, imod_interval);
 
 	xhci_dbg(xhci, "Add secondary interrupter %d, max interrupters %d\n",
-		 i, xhci->max_interrupters);
+		 ir->intr_num, xhci->max_interrupters);
 
 	return ir;
 }

drivers/usb/host/xhci-sideband.c

@@ -259,7 +259,7 @@ EXPORT_SYMBOL_GPL(xhci_sideband_get_event_buffer);
  */
 int
 xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
-				 bool ip_autoclear, u32 imod_interval)
+				 bool ip_autoclear, u32 imod_interval, int intr_num)
 {
 	int ret = 0;
 
@@ -273,7 +273,8 @@ xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
 	}
 
 	sb->ir = xhci_create_secondary_interrupter(xhci_to_hcd(sb->xhci),
-						   num_seg, imod_interval);
+						   num_seg, imod_interval,
+						   intr_num);
 	if (!sb->ir) {
 		ret = -ENOMEM;
 		goto out;

drivers/usb/host/xhci.h

@@ -1853,7 +1853,7 @@ void xhci_free_container_ctx(struct xhci_hcd *xhci,
 		struct xhci_container_ctx *ctx);
 struct xhci_interrupter *
 xhci_create_secondary_interrupter(struct usb_hcd *hcd, unsigned int segs,
-				  u32 imod_interval);
+				  u32 imod_interval, unsigned int intr_num);
 void xhci_remove_secondary_interrupter(struct usb_hcd
 				       *hcd, struct xhci_interrupter *ir);
 void xhci_skip_sec_intr_events(struct xhci_hcd *xhci,

include/linux/usb/xhci-sideband.h

@@ -66,7 +66,7 @@ struct sg_table *
 xhci_sideband_get_event_buffer(struct xhci_sideband *sb);
 int
 xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
-				 bool ip_autoclear, u32 imod_interval);
+				 bool ip_autoclear, u32 imod_interval, int intr_num);
 void
 xhci_sideband_remove_interrupter(struct xhci_sideband *sb);
 int