[PATCH v4 3/5] usb: xhci: sideband: allocate sideband ring segments from a dedicated pool

@@ -9,6 +9,7 @@
  */
 
 #include <linux/usb/xhci-sideband.h>
+#include <linux/dmapool.h>
 
 #include "xhci.h"
 

@@ -67,6 +68,7 @@ __xhci_sideband_remove_endpoint(struct xhci_sideband *sb, struct xhci_virt_ep *e
 	xhci_stop_endpoint_sync(sb->xhci, ep, 0, GFP_KERNEL);
 
 	ep->sideband = NULL;
+	ep->priv_seg_pool = NULL;
 	sb->eps[ep->ep_index] = NULL;
 }
 

@@ -113,6 +115,8 @@ EXPORT_SYMBOL_GPL(xhci_sideband_notify_ep_ring_free);
  * xhci_sideband_add_endpoint - add endpoint to sideband access list
  * @sb: sideband instance for this usb device
  * @host_ep: usb host endpoint
+ * @pool: dma pool to allocate this endpoint's ring segments from, or NULL
+ *        to leave the endpoint's current pool selection untouched
  *
  * Adds an endpoint to the list of sideband accessed endpoints for this usb
  * device.

@@ -123,7 +127,8 @@ EXPORT_SYMBOL_GPL(xhci_sideband_notify_ep_ring_free);
  */
 int
 xhci_sideband_add_endpoint(struct xhci_sideband *sb,
-			   struct usb_host_endpoint *host_ep)
+			   struct usb_host_endpoint *host_ep,
+			   struct dma_pool *pool)
 {
 	struct xhci_virt_ep *ep;
 	unsigned int ep_index;

@@ -153,6 +158,9 @@ xhci_sideband_add_endpoint(struct xhci_sideband *sb,
 	ep->sideband = sb;
 	sb->eps[ep_index] = ep;
 
+	if (pool)
+		ep->priv_seg_pool = pool;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(xhci_sideband_add_endpoint);

@@ -288,6 +296,7 @@ EXPORT_SYMBOL_GPL(xhci_sideband_check);
  * xhci_sideband_create_interrupter - creates a new interrupter for this sideband
  * @sb: sideband instance for this usb device
  * @num_seg: number of event ring segments to allocate
+ * @pool: dma pool to allocate the interrupter's event ring segments from
  * @ip_autoclear: IP autoclearing support such as MSI implemented
  *
  * Sets up a xhci interrupter that can be used for this sideband accessed usb

@@ -301,7 +310,8 @@ EXPORT_SYMBOL_GPL(xhci_sideband_check);
  */
 int
 xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
-				 bool ip_autoclear, u32 imod_interval, int intr_num)
+				 struct dma_pool *pool, bool ip_autoclear,
+				 u32 imod_interval, int intr_num)
 {
 	if (!sb || !sb->xhci)
 		return -ENODEV;

@@ -315,7 +325,7 @@ xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
 		return -EBUSY;
 
 	sb->ir = xhci_create_secondary_interrupter(xhci_to_hcd(sb->xhci),
-						   num_seg, NULL,
+						   num_seg, pool,
 						   imod_interval, intr_num);
 	if (!sb->ir)
 		return -ENOMEM;

@@ -370,6 +380,8 @@ EXPORT_SYMBOL_GPL(xhci_sideband_interrupter_id);
 /**
  * xhci_sideband_register - register a sideband for a usb device
  * @intf: usb interface associated with the sideband device
+ * @type: xHCI sideband type
+ * @notify_client: callback for xHCI sideband sequences
  *
  * Allows for clients to utilize XHCI interrupters and fetch transfer and event
  * ring parameters for executing data transfers.

@@ -436,6 +448,15 @@ EXPORT_SYMBOL_GPL(xhci_sideband_register);
  * After this the endpoint and interrupter event buffers should no longer
  * be accessed via sideband. The xhci driver can now take over handling
  * the buffers.
+ * Any transfer ring allocated from a client supplied dma pool is freed here
+ * as well, as the client is not expected to keep that pool alive any longer
+ * than this call. This includes rings of endpoints already removed with
+ * xhci_sideband_remove_endpoint(), which xhci would otherwise only free once
+ * the device is reconfigured or torn down, i.e. after the client is gone.
+ *
+ * The caller must ensure the usb device is no longer streaming through the
+ * normal, non-sideband path when calling this, as the freed rings are still
+ * referenced by the endpoint contexts until xhci reconfigures the device.
  */
 void
 xhci_sideband_unregister(struct xhci_sideband *sb)

@@ -458,6 +479,17 @@ xhci_sideband_unregister(struct xhci_sideband *sb)
 			if (sb->eps[i])
 				__xhci_sideband_remove_endpoint(sb, sb->eps[i]);
 
+		spin_lock_irq(&xhci->lock);
+		for (i = 0; i < EP_CTX_PER_DEV; i++) {
+			struct xhci_ring *ring = vdev->eps[i].ring;
+
+			if (ring && ring->segment_pool != xhci->segment_pool) {
+				xhci_ring_free(xhci, ring);
+				vdev->eps[i].ring = NULL;
+			}
+		}
+		spin_unlock_irq(&xhci->lock);
+
 		__xhci_sideband_remove_interrupter(sb);
 
 		sb->vdev = NULL;

@@ -19,6 +19,7 @@
 #include <linux/usb/hcd.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/io-64-nonatomic-hi-lo.h>
+#include <linux/usb/xhci-sideband.h>
 
 /* Code sharing between pci-quirks and xhci hcd */
 #include	"xhci-ext-caps.h"

@@ -740,8 +741,6 @@ struct xhci_interval_bw_table {
 	unsigned int		ss_bw_out;
 };
 
-#define EP_CTX_PER_DEV		31
-
 struct xhci_virt_device {
 	int				slot_id;
 	struct usb_device		*udev;

@@ -1255,14 +1254,11 @@ static inline const char *xhci_trb_type_string(u8 type)
 #define NEC_FW_MAJOR(p)		(((p) >> 8) & 0xff)
 
 /*
- * TRBS_PER_SEGMENT must be a multiple of 4,
- * since the command ring is 64-byte aligned.
- * It must also be greater than 16.
+ * TRBS_PER_SEGMENT and TRB_SEGMENT_SIZE are defined in
+ * <linux/usb/xhci-sideband.h>, shared with sideband client drivers.
  */
-#define TRBS_PER_SEGMENT	256
 /* Allow two commands + a link TRB, along with any reserved command TRBs */
 #define MAX_RSVD_CMD_TRBS	(TRBS_PER_SEGMENT - 3)
-#define TRB_SEGMENT_SIZE	(TRBS_PER_SEGMENT*16)
 #define TRB_SEGMENT_SHIFT	(ilog2(TRB_SEGMENT_SIZE))
 /* TRB buffer pointers can't cross 64KB boundaries */
 #define TRB_MAX_BUFF_SHIFT		16

@@ -13,7 +13,19 @@
 #include <linux/usb.h>
 #include <linux/usb/hcd.h>
 
-#define	EP_CTX_PER_DEV		31	/* FIXME defined twice, from xhci.h */
+/*
+ * Constants shared with the xHCI host driver (drivers/usb/host/xhci.h),
+ * which includes this header for its canonical definitions.
+ */
+#define EP_CTX_PER_DEV      31
+
+/*
+ * TRBS_PER_SEGMENT must be a multiple of 4,
+ * since the command ring is 64-byte aligned.
+ * It must also be greater than 16.
+ */
+#define TRBS_PER_SEGMENT    256
+#define TRB_SEGMENT_SIZE    (TRBS_PER_SEGMENT * 16)
 
 struct xhci_sideband;
 

@@ -72,7 +84,8 @@ void
 xhci_sideband_unregister(struct xhci_sideband *sb);
 int
 xhci_sideband_add_endpoint(struct xhci_sideband *sb,
-			   struct usb_host_endpoint *host_ep);
+			   struct usb_host_endpoint *host_ep,
+			   struct dma_pool *pool);
 int
 xhci_sideband_remove_endpoint(struct xhci_sideband *sb,
 			      struct usb_host_endpoint *host_ep);

@@ -94,7 +107,8 @@ static inline bool xhci_sideband_check(struct usb_hcd *hcd)
 
 int
 xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
-				 bool ip_autoclear, u32 imod_interval, int intr_num);
+				 struct dma_pool *pool, bool ip_autoclear,
+				 u32 imod_interval, int intr_num);
 void
 xhci_sideband_remove_interrupter(struct xhci_sideband *sb);
 int

@@ -7,6 +7,7 @@
 #include <linux/ctype.h>
 #include <linux/dma-mapping.h>
 #include <linux/dma-map-ops.h>
+#include <linux/dmapool.h>
 #include <linux/init.h>
 #include <linux/iommu.h>
 #include <linux/module.h>

@@ -131,6 +132,7 @@ struct uaudio_dev {
 
 	/* xhci sideband */
 	struct xhci_sideband *sb;
+	struct dma_pool *segment_pool;
 
 	/* SoC USB device */
 	struct snd_soc_usb_device *sdev;

@@ -1140,7 +1142,8 @@ uaudio_endpoint_setup(struct snd_usb_substream *subs,
 
 	memcpy(ep_desc, &ep->desc, sizeof(ep->desc));
 
-	ret = xhci_sideband_add_endpoint(uadev[card_num].sb, ep);
+	ret = xhci_sideband_add_endpoint(uadev[card_num].sb, ep,
+					 uadev[card_num].segment_pool);
 	if (ret < 0) {
 		dev_err(&subs->dev->dev,
 			"failed to add data ep to sec intr: %d\n", ret);

@@ -1211,8 +1214,9 @@ static int uaudio_event_ring_setup(struct snd_usb_substream *subs,
 		goto exit;
 
 	/* event ring */
-	ret = xhci_sideband_create_interrupter(uadev[card_num].sb, 1, false,
-					       0, uaudio_qdev->data->intr_num);
+	ret = xhci_sideband_create_interrupter(uadev[card_num].sb, 1,
+					       uadev[card_num].segment_pool,
+					       false, 0, uaudio_qdev->data->intr_num);
 	if (ret < 0) {
 		dev_err(&subs->dev->dev, "failed to fetch interrupter\n");
 		goto put_offload;

@@ -1786,6 +1790,7 @@ static void qc_usb_audio_offload_probe(struct snd_usb_audio *chip)
 	struct usb_interface_descriptor *altsd;
 	struct usb_host_interface *alts;
 	struct snd_soc_usb_device *sdev;
+	struct dma_pool *segment_pool;
 	struct xhci_sideband *sb;
 
 	/*

@@ -1804,10 +1809,21 @@ static void qc_usb_audio_offload_probe(struct snd_usb_audio *chip)
 		if (!sdev)
 			return;
 
+		segment_pool = dma_pool_create("xHCI sideband ring segments",
+					       interface_to_usbdev(intf)->bus->sysdev,
+					       TRB_SEGMENT_SIZE, TRB_SEGMENT_SIZE,
+					       TRB_SEGMENT_SIZE);
+		if (!segment_pool)
+			goto free_sdev;
+
 		sb = xhci_sideband_register(intf, XHCI_SIDEBAND_VENDOR,
 					    uaudio_sideband_notifier);
-		if (!sb)
+		if (!sb) {
+			dma_pool_destroy(segment_pool);
 			goto free_sdev;
+		}
+
+		uadev[chip->card->number].segment_pool = segment_pool;
 	} else {
 		sb = uadev[chip->card->number].sb;
 		sdev = uadev[chip->card->number].sdev;

@@ -1844,8 +1860,11 @@ static void qc_usb_audio_offload_probe(struct snd_usb_audio *chip)
 	return;
 
 unreg_xhci:
+	segment_pool = uadev[chip->card->number].segment_pool;
 	xhci_sideband_unregister(sb);
+	dma_pool_destroy(segment_pool);
 	uadev[chip->card->number].sb = NULL;
+	uadev[chip->card->number].segment_pool = NULL;
 free_sdev:
 	kfree(sdev);
 	uadev[chip->card->number].sdev = NULL;

@@ -1905,8 +1924,13 @@ static void qc_usb_audio_offload_disconnect(struct snd_usb_audio *chip)
 	 * This is to accommodate for devices w/ multiple UAC functions.
 	 */
 	if (chip->num_interfaces == 1) {
+		struct dma_pool *segment_pool = dev->segment_pool;
+
 		snd_soc_usb_disconnect(uaudio_qdev->auxdev->dev.parent, dev->sdev);
 		xhci_sideband_unregister(dev->sb);
+		dma_pool_destroy(segment_pool);
+		dev->sb = NULL;
+		dev->segment_pool = NULL;
 		dev->chip = NULL;
 		kfree(dev->sdev->ppcm_idx);
 		kfree(dev->sdev);