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Date:   Thu, 28 Sep 2023 13:31:09 +0300
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To:     Wesley Cheng <quic_wcheng@quicinc.com>, mathias.nyman@intel.com,
        gregkh@linuxfoundation.org, lgirdwood@gmail.com,
        broonie@kernel.org, perex@perex.cz, tiwai@suse.com,
        agross@kernel.org, andersson@kernel.org, konrad.dybcio@linaro.org,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        conor+dt@kernel.org, srinivas.kandagatla@linaro.org,
        bgoswami@quicinc.com, Thinh.Nguyen@synopsys.com
Cc:     linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        alsa-devel@alsa-project.org, linux-arm-msm@vger.kernel.org,
        devicetree@vger.kernel.org
References: <20230921214843.18450-1-quic_wcheng@quicinc.com>
 <20230921214843.18450-2-quic_wcheng@quicinc.com>
From:   Mathias Nyman <mathias.nyman@linux.intel.com>
Subject: Re: [PATCH v7 01/33] xhci: add support to allocate several
 interrupters
In-Reply-To: <20230921214843.18450-2-quic_wcheng@quicinc.com>
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Precedence: bulk

On 22.9.2023 0.48, Wesley Cheng wrote:
> From: Mathias Nyman <mathias.nyman@linux.intel.com>
> 
> Modify the XHCI drivers to accommodate for handling multiple event rings in
> case there are multiple interrupters.  Add the required APIs so clients are
> able to allocate/request for an interrupter ring, and pass this information
> back to the client driver.  This allows for users to handle the resource
> accordingly, such as passing the event ring base address to an audio DSP.
> There is no actual support for multiple MSI/MSI-X vectors.
> 
> Factoring out XHCI interrupter APIs and structures done by Wesley Cheng, in
> order to allow for USB class drivers to utilze them.
> 
> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> Co-developed-by: Wesley Cheng <quic_wcheng@quicinc.com>
> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
> ---
>   drivers/usb/host/xhci-debugfs.c |  2 +-
>   drivers/usb/host/xhci-mem.c     | 93 ++++++++++++++++++++++++++++++---
>   drivers/usb/host/xhci-ring.c    |  2 +-
>   drivers/usb/host/xhci.c         | 49 ++++++++++-------
>   drivers/usb/host/xhci.h         | 77 +--------------------------
>   include/linux/usb/xhci-intr.h   | 86 ++++++++++++++++++++++++++++++
>   6 files changed, 207 insertions(+), 102 deletions(-)
>   create mode 100644 include/linux/usb/xhci-intr.h
> 
> diff --git a/drivers/usb/host/xhci-debugfs.c b/drivers/usb/host/xhci-debugfs.c
> index 99baa60ef50f..15a8402ee8a1 100644
> --- a/drivers/usb/host/xhci-debugfs.c
> +++ b/drivers/usb/host/xhci-debugfs.c
> @@ -693,7 +693,7 @@ void xhci_debugfs_init(struct xhci_hcd *xhci)
>   				     "command-ring",
>   				     xhci->debugfs_root);
>   
> -	xhci_debugfs_create_ring_dir(xhci, &xhci->interrupter->event_ring,
> +	xhci_debugfs_create_ring_dir(xhci, &xhci->interrupters[0]->event_ring,
>   				     "event-ring",
>   				     xhci->debugfs_root);
>   
> diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> index 8714ab5bf04d..2f9228d7d22d 100644
> --- a/drivers/usb/host/xhci-mem.c
> +++ b/drivers/usb/host/xhci-mem.c
> @@ -1837,6 +1837,26 @@ xhci_free_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
>   	kfree(ir);
>   }
>   
> +void xhci_remove_secondary_interrupter(struct usb_hcd *hcd, struct xhci_interrupter *ir)
> +{
> +	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> +	unsigned int intr_num;
> +
> +	/* interrupter 0 is primary interrupter, don't touch it */
> +	if (!ir || !ir->intr_num || ir->intr_num >= xhci->max_interrupters) {
> +		xhci_dbg(xhci, "Invalid secondary interrupter, can't remove\n");
> +		return;
> +	}
> +
> +	/* fixme, should we check xhci->interrupter[intr_num] == ir */
> +	spin_lock(&xhci->lock);

Needs to be spin_lock_irq() ir spin_lock_irqsave() as xhci->lock is used in interrupt handler.


> +	intr_num = ir->intr_num;
> +	xhci_free_interrupter(xhci, ir);
> +	xhci->interrupters[intr_num] = NULL;
> +	spin_unlock(&xhci->lock);

likewise

> +}
> +EXPORT_SYMBOL_GPL(xhci_remove_secondary_interrupter);
> +
>   void xhci_mem_cleanup(struct xhci_hcd *xhci)
>   {
>   	struct device	*dev = xhci_to_hcd(xhci)->self.sysdev;
> @@ -1844,9 +1864,13 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
>   
>   	cancel_delayed_work_sync(&xhci->cmd_timer);
>   
> -	xhci_free_interrupter(xhci, xhci->interrupter);
> -	xhci->interrupter = NULL;
> -	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Freed primary event ring");
> +	for (i = 0; i < xhci->max_interrupters; i++) {
> +		if (xhci->interrupters[i]) {
> +			xhci_free_interrupter(xhci, xhci->interrupters[i]);
> +			xhci->interrupters[i] = NULL;
> +		}
> +	}
> +	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Freed interrupters");
>   
>   	if (xhci->cmd_ring)
>   		xhci_ring_free(xhci, xhci->cmd_ring);
> @@ -1916,6 +1940,7 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
>   	for (i = 0; i < xhci->num_port_caps; i++)
>   		kfree(xhci->port_caps[i].psi);
>   	kfree(xhci->port_caps);
> +	kfree(xhci->interrupters);
>   	xhci->num_port_caps = 0;
>   
>   	xhci->usb2_rhub.ports = NULL;
> @@ -1924,6 +1949,7 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
>   	xhci->rh_bw = NULL;
>   	xhci->ext_caps = NULL;
>   	xhci->port_caps = NULL;
> +	xhci->interrupters = NULL;
>   
>   	xhci->page_size = 0;
>   	xhci->page_shift = 0;
> @@ -2276,6 +2302,13 @@ xhci_add_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
>   		return -EINVAL;
>   	}
>   
> +	if (xhci->interrupters[intr_num]) {
> +		xhci_warn(xhci, "Interrupter %d\n already set up", intr_num);
> +		return -EINVAL;
> +	}
> +
> +	xhci->interrupters[intr_num] = ir;
> +	ir->intr_num = intr_num;
>   	ir->ir_set = &xhci->run_regs->ir_set[intr_num];
>   
>   	/* set ERST count with the number of entries in the segment table */
> @@ -2295,10 +2328,53 @@ xhci_add_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
>   	return 0;
>   }
>   
> +struct xhci_interrupter *
> +xhci_create_secondary_interrupter(struct usb_hcd *hcd)
> +{
> +	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> +	struct xhci_interrupter *ir;
> +	unsigned int i;
> +	int err = -ENOSPC;
> +
> +	if (!xhci->interrupters)
> +		return NULL;
> +
> +	ir = xhci_alloc_interrupter(xhci, GFP_KERNEL);
> +	if (!ir)
> +		return NULL;
> +
> +	spin_lock_irq(&xhci->lock);
> +
> +	/* Find available secondary interrupter, interrupter 0 is reserverd for primary */

reserved

> +	for (i = 1; i < xhci->max_interrupters; i++) {
> +		if (xhci->interrupters[i] == NULL) {
> +			err = xhci_add_interrupter(xhci, ir, i);
> +			break;
> +		}
> +	}
> +
> +	spin_unlock_irq(&xhci->lock);
> +	if (err) {
> +		xhci_warn(xhci, "Failed to add secondary interrupter, max interrupters %d\n",
> +			xhci->max_interrupters);
> +		xhci_free_interrupter(xhci, ir);
> +		ir = NULL;
> +		goto out;
> +	}
> +
> +	xhci_dbg(xhci, "Add secondary interrupter %d, max interrupters %d\n",
> +		 i, xhci->max_interrupters);
> +
> +out:
> +	return ir;
> +}
> +EXPORT_SYMBOL_GPL(xhci_create_secondary_interrupter);
> +
>   int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
>   {
> -	dma_addr_t	dma;
> +	struct xhci_interrupter *ir;
>   	struct device	*dev = xhci_to_hcd(xhci)->self.sysdev;
> +	dma_addr_t	dma;
>   	unsigned int	val, val2;
>   	u64		val_64;
>   	u32		page_size, temp;
> @@ -2422,11 +2498,14 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
>   	/* Allocate and set up primary interrupter 0 with an event ring. */
>   	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
>   		       "Allocating primary event ring");
> -	xhci->interrupter = xhci_alloc_interrupter(xhci, flags);
> -	if (!xhci->interrupter)
> +	xhci->interrupters = kcalloc_node(xhci->max_interrupters, sizeof(*xhci->interrupters),
> +					  flags, dev_to_node(dev));
> +
> +	ir = xhci_alloc_interrupter(xhci, flags);
> +	if (!ir)
>   		goto fail;
>   
> -	if (xhci_add_interrupter(xhci, xhci->interrupter, 0))
> +	if (xhci_add_interrupter(xhci, ir, 0))
>   		goto fail;
>   
>   	xhci->isoc_bei_interval = AVOID_BEI_INTERVAL_MAX;
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index 1dde53f6eb31..93233cf5ff21 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -3074,7 +3074,7 @@ irqreturn_t xhci_irq(struct usb_hcd *hcd)
>   	writel(status, &xhci->op_regs->status);
>   
>   	/* This is the handler of the primary interrupter */
> -	ir = xhci->interrupter;
> +	ir = xhci->interrupters[0];
>   	if (!hcd->msi_enabled) {
>   		u32 irq_pending;
>   		irq_pending = readl(&ir->ir_set->irq_pending);
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index e1b1b64a0723..3fd2b58ee1d3 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -456,7 +456,7 @@ static int xhci_init(struct usb_hcd *hcd)
>   
>   static int xhci_run_finished(struct xhci_hcd *xhci)
>   {
> -	struct xhci_interrupter *ir = xhci->interrupter;
> +	struct xhci_interrupter *ir = xhci->interrupters[0];
>   	unsigned long	flags;
>   	u32		temp;
>   
> @@ -508,7 +508,7 @@ int xhci_run(struct usb_hcd *hcd)
>   	u64 temp_64;
>   	int ret;
>   	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> -	struct xhci_interrupter *ir = xhci->interrupter;
> +	struct xhci_interrupter *ir = xhci->interrupters[0];
>   	/* Start the xHCI host controller running only after the USB 2.0 roothub
>   	 * is setup.
>   	 */
> @@ -572,7 +572,7 @@ void xhci_stop(struct usb_hcd *hcd)
>   {
>   	u32 temp;
>   	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> -	struct xhci_interrupter *ir = xhci->interrupter;
> +	struct xhci_interrupter *ir = xhci->interrupters[0];
>   
>   	mutex_lock(&xhci->mutex);
>   
> @@ -668,36 +668,49 @@ EXPORT_SYMBOL_GPL(xhci_shutdown);
>   #ifdef CONFIG_PM
>   static void xhci_save_registers(struct xhci_hcd *xhci)
>   {
> -	struct xhci_interrupter *ir = xhci->interrupter;
> +	struct xhci_interrupter *ir;
> +	unsigned int i;
>   
>   	xhci->s3.command = readl(&xhci->op_regs->command);
>   	xhci->s3.dev_nt = readl(&xhci->op_regs->dev_notification);
>   	xhci->s3.dcbaa_ptr = xhci_read_64(xhci, &xhci->op_regs->dcbaa_ptr);
>   	xhci->s3.config_reg = readl(&xhci->op_regs->config_reg);
>   
> -	if (!ir)
> -		return;
> +	/* save both primary and all secondary interrupters */
> +	for (i = 0; i < xhci->max_interrupters; i++) {
> +		ir = xhci->interrupters[i];
> +		if (!ir)
> +			continue;
>   
> -	ir->s3_erst_size = readl(&ir->ir_set->erst_size);
> -	ir->s3_erst_base = xhci_read_64(xhci, &ir->ir_set->erst_base);
> -	ir->s3_erst_dequeue = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
> -	ir->s3_irq_pending = readl(&ir->ir_set->irq_pending);
> -	ir->s3_irq_control = readl(&ir->ir_set->irq_control);
> +		ir->s3_erst_size = readl(&ir->ir_set->erst_size);
> +		ir->s3_erst_base = xhci_read_64(xhci, &ir->ir_set->erst_base);
> +		ir->s3_erst_dequeue = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
> +		ir->s3_irq_pending = readl(&ir->ir_set->irq_pending);
> +		ir->s3_irq_control = readl(&ir->ir_set->irq_control);
> +	}
>   }
>   
>   static void xhci_restore_registers(struct xhci_hcd *xhci)
>   {
> -	struct xhci_interrupter *ir = xhci->interrupter;
> +	struct xhci_interrupter *ir;
> +	unsigned int i;
>   
>   	writel(xhci->s3.command, &xhci->op_regs->command);
>   	writel(xhci->s3.dev_nt, &xhci->op_regs->dev_notification);
>   	xhci_write_64(xhci, xhci->s3.dcbaa_ptr, &xhci->op_regs->dcbaa_ptr);
>   	writel(xhci->s3.config_reg, &xhci->op_regs->config_reg);
> -	writel(ir->s3_erst_size, &ir->ir_set->erst_size);
> -	xhci_write_64(xhci, ir->s3_erst_base, &ir->ir_set->erst_base);
> -	xhci_write_64(xhci, ir->s3_erst_dequeue, &ir->ir_set->erst_dequeue);
> -	writel(ir->s3_irq_pending, &ir->ir_set->irq_pending);
> -	writel(ir->s3_irq_control, &ir->ir_set->irq_control);
> +
> +	for (i = 0; i < xhci->max_interrupters; i++) {
> +		ir = xhci->interrupters[i];
> +		if (!ir)
> +			continue;
> +
> +		writel(ir->s3_erst_size, &ir->ir_set->erst_size);
> +		xhci_write_64(xhci, ir->s3_erst_base, &ir->ir_set->erst_base);
> +		xhci_write_64(xhci, ir->s3_erst_dequeue, &ir->ir_set->erst_dequeue);
> +		writel(ir->s3_irq_pending, &ir->ir_set->irq_pending);
> +		writel(ir->s3_irq_control, &ir->ir_set->irq_control);
> +	}
>   }
>   
>   static void xhci_set_cmd_ring_deq(struct xhci_hcd *xhci)
> @@ -1059,7 +1072,7 @@ int xhci_resume(struct xhci_hcd *xhci, pm_message_t msg)
>   		xhci_dbg(xhci, "// Disabling event ring interrupts\n");
>   		temp = readl(&xhci->op_regs->status);
>   		writel((temp & ~0x1fff) | STS_EINT, &xhci->op_regs->status);
> -		xhci_disable_interrupter(xhci->interrupter);
> +		xhci_disable_interrupter(xhci->interrupters[0]);
>   
>   		xhci_dbg(xhci, "cleaning up memory\n");
>   		xhci_mem_cleanup(xhci);

All code above looks like it should be its own patch.

The header shuffling below part of somethine else.

> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index 7e282b4522c0..d706a27ec0a3 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -17,6 +17,7 @@
>   #include <linux/kernel.h>
>   #include <linux/usb/hcd.h>
>   #include <linux/io-64-nonatomic-lo-hi.h>
> +#include <linux/usb/xhci-intr.h>
>   
>   /* Code sharing between pci-quirks and xhci hcd */
>   #include	"xhci-ext-caps.h"
> @@ -1541,18 +1542,6 @@ static inline const char *xhci_trb_type_string(u8 type)
>   #define AVOID_BEI_INTERVAL_MIN	8
>   #define AVOID_BEI_INTERVAL_MAX	32
>   
> -struct xhci_segment {
> -	union xhci_trb		*trbs;
> -	/* private to HCD */
> -	struct xhci_segment	*next;
> -	dma_addr_t		dma;
> -	/* Max packet sized bounce buffer for td-fragmant alignment */
> -	dma_addr_t		bounce_dma;
> -	void			*bounce_buf;
> -	unsigned int		bounce_offs;
> -	unsigned int		bounce_len;
> -};
> -
>   enum xhci_cancelled_td_status {
>   	TD_DIRTY = 0,
>   	TD_HALTED,
> @@ -1585,16 +1574,6 @@ struct xhci_cd {
>   	union xhci_trb		*cmd_trb;
>   };
>   
> -enum xhci_ring_type {
> -	TYPE_CTRL = 0,
> -	TYPE_ISOC,
> -	TYPE_BULK,
> -	TYPE_INTR,
> -	TYPE_STREAM,
> -	TYPE_COMMAND,
> -	TYPE_EVENT,
> -};
> -
>   static inline const char *xhci_ring_type_string(enum xhci_ring_type type)
>   {
>   	switch (type) {
> @@ -1615,46 +1594,6 @@ static inline const char *xhci_ring_type_string(enum xhci_ring_type type)
>   	}
>   
>   	return "UNKNOWN";
> -}
> -
> -struct xhci_ring {
> -	struct xhci_segment	*first_seg;
> -	struct xhci_segment	*last_seg;
> -	union  xhci_trb		*enqueue;
> -	struct xhci_segment	*enq_seg;
> -	union  xhci_trb		*dequeue;
> -	struct xhci_segment	*deq_seg;
> -	struct list_head	td_list;
> -	/*
> -	 * 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
> -	 * if we own the TRB (if we are the consumer).  See section 4.9.1.
> -	 */
> -	u32			cycle_state;
> -	unsigned int		stream_id;
> -	unsigned int		num_segs;
> -	unsigned int		num_trbs_free; /* used only by xhci DbC */
> -	unsigned int		bounce_buf_len;
> -	enum xhci_ring_type	type;
> -	bool			last_td_was_short;
> -	struct radix_tree_root	*trb_address_map;
> -};
> -
> -struct xhci_erst_entry {
> -	/* 64-bit event ring segment address */
> -	__le64	seg_addr;
> -	__le32	seg_size;
> -	/* Set to zero */
> -	__le32	rsvd;
> -};
> -
> -struct xhci_erst {
> -	struct xhci_erst_entry	*entries;
> -	unsigned int		num_entries;
> -	/* xhci->event_ring keeps track of segment dma addresses */
> -	dma_addr_t		erst_dma_addr;
> -	/* Num entries the ERST can contain */
> -	unsigned int		erst_size;
>   };
>   
>   struct xhci_scratchpad {
> @@ -1707,18 +1646,6 @@ struct xhci_bus_state {
>   	unsigned long		resuming_ports;
>   };
>   
> -struct xhci_interrupter {
> -	struct xhci_ring	*event_ring;
> -	struct xhci_erst	erst;
> -	struct xhci_intr_reg __iomem *ir_set;
> -	unsigned int		intr_num;
> -	/* For interrupter registers save and restore over suspend/resume */
> -	u32	s3_irq_pending;
> -	u32	s3_irq_control;
> -	u32	s3_erst_size;
> -	u64	s3_erst_base;
> -	u64	s3_erst_dequeue;
> -};
>   /*
>    * It can take up to 20 ms to transition from RExit to U0 on the
>    * Intel Lynx Point LP xHCI host.
> @@ -1799,7 +1726,7 @@ struct xhci_hcd {
>   	struct reset_control *reset;
>   	/* data structures */
>   	struct xhci_device_context_array *dcbaa;
> -	struct xhci_interrupter *interrupter;
> +	struct xhci_interrupter **interrupters;
>   	struct xhci_ring	*cmd_ring;
>   	unsigned int            cmd_ring_state;
>   #define CMD_RING_STATE_RUNNING         (1 << 0)
> diff --git a/include/linux/usb/xhci-intr.h b/include/linux/usb/xhci-intr.h
> new file mode 100644
> index 000000000000..e0091ee2c73a
> --- /dev/null
> +++ b/include/linux/usb/xhci-intr.h
> @@ -0,0 +1,86 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __LINUX_XHCI_INTR_H
> +#define __LINUX_XHCI_INTR_H
> +
> +#include <linux/kernel.h>
> +
> +struct xhci_erst_entry {
> +	/* 64-bit event ring segment address */
> +	__le64	seg_addr;
> +	__le32	seg_size;
> +	/* Set to zero */
> +	__le32	rsvd;
> +};
> +
> +enum xhci_ring_type {
> +	TYPE_CTRL = 0,
> +	TYPE_ISOC,
> +	TYPE_BULK,
> +	TYPE_INTR,
> +	TYPE_STREAM,
> +	TYPE_COMMAND,
> +	TYPE_EVENT,
> +};
> +
> +struct xhci_erst {
> +	struct xhci_erst_entry	*entries;
> +	unsigned int		num_entries;
> +	/* xhci->event_ring keeps track of segment dma addresses */
> +	dma_addr_t		erst_dma_addr;
> +	/* Num entries the ERST can contain */
> +	unsigned int		erst_size;
> +};
> +
> +struct xhci_segment {
> +	union xhci_trb		*trbs;
> +	/* private to HCD */
> +	struct xhci_segment	*next;
> +	dma_addr_t		dma;
> +	/* Max packet sized bounce buffer for td-fragmant alignment */
> +	dma_addr_t		bounce_dma;
> +	void			*bounce_buf;
> +	unsigned int		bounce_offs;
> +	unsigned int		bounce_len;
> +};
> +
> +struct xhci_ring {
> +	struct xhci_segment	*first_seg;
> +	struct xhci_segment	*last_seg;
> +	union  xhci_trb		*enqueue;
> +	struct xhci_segment	*enq_seg;
> +	union  xhci_trb		*dequeue;
> +	struct xhci_segment	*deq_seg;
> +	struct list_head	td_list;
> +	/*
> +	 * 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
> +	 * if we own the TRB (if we are the consumer).  See section 4.9.1.
> +	 */
> +	u32			cycle_state;
> +	unsigned int		stream_id;
> +	unsigned int		num_segs;
> +	unsigned int		num_trbs_free;
> +	unsigned int		num_trbs_free_temp;
> +	unsigned int		bounce_buf_len;
> +	enum xhci_ring_type	type;
> +	bool			last_td_was_short;
> +	struct radix_tree_root	*trb_address_map;
> +};
> +
> +struct xhci_interrupter {
> +	struct xhci_ring	*event_ring;
> +	struct xhci_erst	erst;
> +	struct xhci_intr_reg __iomem *ir_set;
> +	unsigned int		intr_num;
> +	/* For interrupter registers save and restore over suspend/resume */
> +	u32	s3_irq_pending;
> +	u32	s3_irq_control;
> +	u32	s3_erst_size;
> +	u64	s3_erst_base;
> +	u64	s3_erst_dequeue;
> +};
> +
> +struct xhci_interrupter *
> +xhci_create_secondary_interrupter(struct usb_hcd *hcd);
> +void xhci_remove_secondary_interrupter(struct usb_hcd *hcd, struct xhci_interrupter *ir);
> +#endif
> 

Not convinced we want to share all these xhci private structures in a separate
header outside of the xhci code.

As much as possible should be abstracted and added to the xhci sideband
API in patch 3/33 instead of sharing these.
  
Thanks
Mathias