Add support for using a MAX3421E chip as a host driver.

Signed-off-by: David Mosberger <davidm@egauge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/Makefile

@@ -28,6 +28,7 @@ obj-$(CONFIG_USB_IMX21_HCD)	+= host/
 obj-$(CONFIG_USB_FSL_MPH_DR_OF)	+= host/
 obj-$(CONFIG_USB_FUSBH200_HCD)	+= host/
 obj-$(CONFIG_USB_FOTG210_HCD)	+= host/
+obj-$(CONFIG_USB_MAX3421_HCD)	+= host/
 
 obj-$(CONFIG_USB_C67X00_HCD)	+= c67x00/
 

drivers/usb/host/Kconfig

@@ -342,6 +342,17 @@ config USB_FOTG210_HCD
 	  To compile this driver as a module, choose M here: the
 	  module will be called fotg210-hcd.
 
+config USB_MAX3421_HCD
+	tristate "MAX3421 HCD (USB-over-SPI) support"
+	depends on USB && SPI
+	---help---
+	  The Maxim MAX3421E chip supports standard USB 2.0-compliant
+	  full-speed devices either in host or peripheral mode.  This
+	  driver supports the host-mode of the MAX3421E only.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called max3421-hcd.
+
 config USB_OHCI_HCD
 	tristate "OHCI HCD (USB 1.1) support"
 	select ISP1301_OMAP if MACH_OMAP_H2 || MACH_OMAP_H3

drivers/usb/host/Makefile

@@ -70,3 +70,4 @@ obj-$(CONFIG_USB_HCD_BCMA)	+= bcma-hcd.o
 obj-$(CONFIG_USB_HCD_SSB)	+= ssb-hcd.o
 obj-$(CONFIG_USB_FUSBH200_HCD)	+= fusbh200-hcd.o
 obj-$(CONFIG_USB_FOTG210_HCD)	+= fotg210-hcd.o
+obj-$(CONFIG_USB_MAX3421_HCD)	+= max3421-hcd.o

drivers/usb/host/max3421-hcd.c

+/*
+ * MAX3421 Host Controller driver for USB.
+ *
+ * Author: David Mosberger-Tang <davidm@egauge.net>
+ *
+ * (C) Copyright 2014 David Mosberger-Tang <davidm@egauge.net>
+ *
+ * MAX3421 is a chip implementing a USB 2.0 Full-/Low-Speed host
+ * controller on a SPI bus.
+ *
+ * Based on:
+ *	o MAX3421E datasheet
+ *		http://datasheets.maximintegrated.com/en/ds/MAX3421E.pdf
+ *	o MAX3421E Programming Guide
+ *		http://www.hdl.co.jp/ftpdata/utl-001/AN3785.pdf
+ *	o gadget/dummy_hcd.c
+ *		For USB HCD implementation.
+ *	o Arduino MAX3421 driver
+ *	     https://github.com/felis/USB_Host_Shield_2.0/blob/master/Usb.cpp
+ *
+ * This file is licenced under the GPL v2.
+ *
+ * Important note on worst-case (full-speed) packet size constraints
+ * (See USB 2.0 Section 5.6.3 and following):
+ *
+ *	- control:	  64 bytes
+ *	- isochronous:	1023 bytes
+ *	- interrupt:	  64 bytes
+ *	- bulk:		  64 bytes
+ *
+ * Since the MAX3421 FIFO size is 64 bytes, we do not have to work about
+ * multi-FIFO writes/reads for a single USB packet *except* for isochronous
+ * transfers.  We don't support isochronous transfers at this time, so we
+ * just assume that a USB packet always fits into a single FIFO buffer.
+ *
+ * NOTE: The June 2006 version of "MAX3421E Programming Guide"
+ * (AN3785) has conflicting info for the RCVDAVIRQ bit:
+ *
+ *	The description of RCVDAVIRQ says "The CPU *must* clear
+ *	this IRQ bit (by writing a 1 to it) before reading the
+ *	RCVFIFO data.
+ *
+ * However, the earlier section on "Programming BULK-IN
+ * Transfers" says * that:
+ *
+ *	After the CPU retrieves the data, it clears the
+ *	RCVDAVIRQ bit.
+ *
+ * The December 2006 version has been corrected and it consistently
+ * states the second behavior is the correct one.
+ *
+ * Synchronous SPI transactions sleep so we can't perform any such
+ * transactions while holding a spin-lock (and/or while interrupts are
+ * masked).  To achieve this, all SPI transactions are issued from a
+ * single thread (max3421_spi_thread).
+ */
+
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/usb.h>
+#include <linux/usb/hcd.h>
+
+#include <linux/platform_data/max3421-hcd.h>
+
+#define DRIVER_DESC	"MAX3421 USB Host-Controller Driver"
+#define DRIVER_VERSION	"1.0"
+
+/* 11-bit counter that wraps around (USB 2.0 Section 8.3.3): */
+#define USB_MAX_FRAME_NUMBER	0x7ff
+#define USB_MAX_RETRIES		3 /* # of retries before error is reported */
+
+/*
+ * Max. # of times we're willing to retransmit a request immediately in
+ * resposne to a NAK.  Afterwards, we fall back on trying once a frame.
+ */
+#define NAK_MAX_FAST_RETRANSMITS	2
+
+#define POWER_BUDGET	500	/* in mA; use 8 for low-power port testing */
+
+/* Port-change mask: */
+#define PORT_C_MASK	((USB_PORT_STAT_C_CONNECTION |	\
+			  USB_PORT_STAT_C_ENABLE |	\
+			  USB_PORT_STAT_C_SUSPEND |	\
+			  USB_PORT_STAT_C_OVERCURRENT | \
+			  USB_PORT_STAT_C_RESET) << 16)
+
+enum max3421_rh_state {
+	MAX3421_RH_RESET,
+	MAX3421_RH_SUSPENDED,
+	MAX3421_RH_RUNNING
+};
+
+enum pkt_state {
+	PKT_STATE_SETUP,	/* waiting to send setup packet to ctrl pipe */
+	PKT_STATE_TRANSFER,	/* waiting to xfer transfer_buffer */
+	PKT_STATE_TERMINATE	/* waiting to terminate control transfer */
+};
+
+enum scheduling_pass {
+	SCHED_PASS_PERIODIC,
+	SCHED_PASS_NON_PERIODIC,
+	SCHED_PASS_DONE
+};
+
+struct max3421_hcd {
+	spinlock_t lock;
+
+	struct task_struct *spi_thread;
+
+	struct max3421_hcd *next;
+
+	enum max3421_rh_state rh_state;
+	/* lower 16 bits contain port status, upper 16 bits the change mask: */
+	u32 port_status;
+
+	unsigned active:1;
+
+	struct list_head ep_list;	/* list of EP's with work */
+
+	/*
+	 * The following are owned by spi_thread (may be accessed by
+	 * SPI-thread without acquiring the HCD lock:
+	 */
+	u8 rev;				/* chip revision */
+	u16 frame_number;
+	/*
+	 * URB we're currently processing.  Must not be reset to NULL
+	 * unless MAX3421E chip is idle:
+	 */
+	struct urb *curr_urb;
+	enum scheduling_pass sched_pass;
+	struct usb_device *loaded_dev;	/* dev that's loaded into the chip */
+	int loaded_epnum;		/* epnum whose toggles are loaded */
+	int urb_done;			/* > 0 -> no errors, < 0: errno */
+	size_t curr_len;
+	u8 hien;
+	u8 mode;
+	u8 iopins[2];
+	unsigned int do_enable_irq:1;
+	unsigned int do_reset_hcd:1;
+	unsigned int do_reset_port:1;
+	unsigned int do_check_unlink:1;
+	unsigned int do_iopin_update:1;
+#ifdef DEBUG
+	unsigned long err_stat[16];
+#endif
+};
+
+struct max3421_ep {
+	struct usb_host_endpoint *ep;
+	struct list_head ep_list;
+	u32 naks;
+	u16 last_active;		/* frame # this ep was last active */
+	enum pkt_state pkt_state;
+	u8 retries;
+	u8 retransmit;			/* packet needs retransmission */
+};
+
+static struct max3421_hcd *max3421_hcd_list;
+
+#define MAX3421_FIFO_SIZE	64
+
+#define MAX3421_SPI_DIR_RD	0	/* read register from MAX3421 */
+#define MAX3421_SPI_DIR_WR	1	/* write register to MAX3421 */
+
+/* SPI commands: */
+#define MAX3421_SPI_DIR_SHIFT	1
+#define MAX3421_SPI_REG_SHIFT	3
+
+#define MAX3421_REG_RCVFIFO	1
+#define MAX3421_REG_SNDFIFO	2
+#define MAX3421_REG_SUDFIFO	4
+#define MAX3421_REG_RCVBC	6
+#define MAX3421_REG_SNDBC	7
+#define MAX3421_REG_USBIRQ	13
+#define MAX3421_REG_USBIEN	14
+#define MAX3421_REG_USBCTL	15
+#define MAX3421_REG_CPUCTL	16
+#define MAX3421_REG_PINCTL	17
+#define MAX3421_REG_REVISION	18
+#define MAX3421_REG_IOPINS1	20
+#define MAX3421_REG_IOPINS2	21
+#define MAX3421_REG_GPINIRQ	22
+#define MAX3421_REG_GPINIEN	23
+#define MAX3421_REG_GPINPOL	24
+#define MAX3421_REG_HIRQ	25
+#define MAX3421_REG_HIEN	26
+#define MAX3421_REG_MODE	27
+#define MAX3421_REG_PERADDR	28
+#define MAX3421_REG_HCTL	29
+#define MAX3421_REG_HXFR	30
+#define MAX3421_REG_HRSL	31
+
+enum {
+	MAX3421_USBIRQ_OSCOKIRQ_BIT = 0,
+	MAX3421_USBIRQ_NOVBUSIRQ_BIT = 5,
+	MAX3421_USBIRQ_VBUSIRQ_BIT
+};
+
+enum {
+	MAX3421_CPUCTL_IE_BIT = 0,
+	MAX3421_CPUCTL_PULSEWID0_BIT = 6,
+	MAX3421_CPUCTL_PULSEWID1_BIT
+};
+
+enum {
+	MAX3421_USBCTL_PWRDOWN_BIT = 4,
+	MAX3421_USBCTL_CHIPRES_BIT
+};
+
+enum {
+	MAX3421_PINCTL_GPXA_BIT	= 0,
+	MAX3421_PINCTL_GPXB_BIT,
+	MAX3421_PINCTL_POSINT_BIT,
+	MAX3421_PINCTL_INTLEVEL_BIT,
+	MAX3421_PINCTL_FDUPSPI_BIT,
+	MAX3421_PINCTL_EP0INAK_BIT,
+	MAX3421_PINCTL_EP2INAK_BIT,
+	MAX3421_PINCTL_EP3INAK_BIT,
+};
+
+enum {
+	MAX3421_HI_BUSEVENT_BIT = 0,	/* bus-reset/-resume */
+	MAX3421_HI_RWU_BIT,		/* remote wakeup */
+	MAX3421_HI_RCVDAV_BIT,		/* receive FIFO data available */
+	MAX3421_HI_SNDBAV_BIT,		/* send buffer available */
+	MAX3421_HI_SUSDN_BIT,		/* suspend operation done */
+	MAX3421_HI_CONDET_BIT,		/* peripheral connect/disconnect */
+	MAX3421_HI_FRAME_BIT,		/* frame generator */
+	MAX3421_HI_HXFRDN_BIT,		/* host transfer done */
+};
+
+enum {
+	MAX3421_HCTL_BUSRST_BIT = 0,
+	MAX3421_HCTL_FRMRST_BIT,
+	MAX3421_HCTL_SAMPLEBUS_BIT,
+	MAX3421_HCTL_SIGRSM_BIT,
+	MAX3421_HCTL_RCVTOG0_BIT,
+	MAX3421_HCTL_RCVTOG1_BIT,
+	MAX3421_HCTL_SNDTOG0_BIT,
+	MAX3421_HCTL_SNDTOG1_BIT
+};
+
+enum {
+	MAX3421_MODE_HOST_BIT = 0,
+	MAX3421_MODE_LOWSPEED_BIT,
+	MAX3421_MODE_HUBPRE_BIT,
+	MAX3421_MODE_SOFKAENAB_BIT,
+	MAX3421_MODE_SEPIRQ_BIT,
+	MAX3421_MODE_DELAYISO_BIT,
+	MAX3421_MODE_DMPULLDN_BIT,
+	MAX3421_MODE_DPPULLDN_BIT
+};
+
+enum {
+	MAX3421_HRSL_OK = 0,
+	MAX3421_HRSL_BUSY,
+	MAX3421_HRSL_BADREQ,
+	MAX3421_HRSL_UNDEF,
+	MAX3421_HRSL_NAK,
+	MAX3421_HRSL_STALL,
+	MAX3421_HRSL_TOGERR,
+	MAX3421_HRSL_WRONGPID,
+	MAX3421_HRSL_BADBC,
+	MAX3421_HRSL_PIDERR,
+	MAX3421_HRSL_PKTERR,
+	MAX3421_HRSL_CRCERR,
+	MAX3421_HRSL_KERR,
+	MAX3421_HRSL_JERR,
+	MAX3421_HRSL_TIMEOUT,
+	MAX3421_HRSL_BABBLE,
+	MAX3421_HRSL_RESULT_MASK = 0xf,
+	MAX3421_HRSL_RCVTOGRD_BIT = 4,
+	MAX3421_HRSL_SNDTOGRD_BIT,
+	MAX3421_HRSL_KSTATUS_BIT,
+	MAX3421_HRSL_JSTATUS_BIT
+};
+
+/* Return same error-codes as ohci.h:cc_to_error: */
+static const int hrsl_to_error[] = {
+	[MAX3421_HRSL_OK] =		0,
+	[MAX3421_HRSL_BUSY] =		-EINVAL,
+	[MAX3421_HRSL_BADREQ] =		-EINVAL,
+	[MAX3421_HRSL_UNDEF] =		-EINVAL,
+	[MAX3421_HRSL_NAK] =		-EAGAIN,
+	[MAX3421_HRSL_STALL] =		-EPIPE,
+	[MAX3421_HRSL_TOGERR] =		-EILSEQ,
+	[MAX3421_HRSL_WRONGPID] =	-EPROTO,
+	[MAX3421_HRSL_BADBC] =		-EREMOTEIO,
+	[MAX3421_HRSL_PIDERR] =		-EPROTO,
+	[MAX3421_HRSL_PKTERR] =		-EPROTO,
+	[MAX3421_HRSL_CRCERR] =		-EILSEQ,
+	[MAX3421_HRSL_KERR] =		-EIO,
+	[MAX3421_HRSL_JERR] =		-EIO,
+	[MAX3421_HRSL_TIMEOUT] =	-ETIME,
+	[MAX3421_HRSL_BABBLE] =		-EOVERFLOW
+};
+
+/*
+ * See http://www.beyondlogic.org/usbnutshell/usb4.shtml#Control for a
+ * reasonable overview of how control transfers use the the IN/OUT
+ * tokens.
+ */
+#define MAX3421_HXFR_BULK_IN(ep)	(0x00 | (ep))	/* bulk or interrupt */
+#define MAX3421_HXFR_SETUP		 0x10
+#define MAX3421_HXFR_BULK_OUT(ep)	(0x20 | (ep))	/* bulk or interrupt */
+#define MAX3421_HXFR_ISO_IN(ep)		(0x40 | (ep))
+#define MAX3421_HXFR_ISO_OUT(ep)	(0x60 | (ep))
+#define MAX3421_HXFR_HS_IN		 0x80		/* handshake in */
+#define MAX3421_HXFR_HS_OUT		 0xa0		/* handshake out */
+
+#define field(val, bit)	((val) << (bit))
+
+static inline s16
+frame_diff(u16 left, u16 right)
+{
+	return ((unsigned) (left - right)) % (USB_MAX_FRAME_NUMBER + 1);
+}
+
+static inline struct max3421_hcd *
+hcd_to_max3421(struct usb_hcd *hcd)
+{
+	return (struct max3421_hcd *) hcd->hcd_priv;
+}
+
+static inline struct usb_hcd *
+max3421_to_hcd(struct max3421_hcd *max3421_hcd)
+{
+	return container_of((void *) max3421_hcd, struct usb_hcd, hcd_priv);
+}
+
+static u8
+spi_rd8(struct usb_hcd *hcd, unsigned int reg)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct spi_transfer transfer;
+	u8 tx_data[1];
+	/*
+	 * RX data must be in its own cache-line so it stays flushed
+	 * from the cache until the transfer is complete.  Otherwise,
+	 * we get stale data from the cache.
+	 */
+	u8 rx_data[SMP_CACHE_BYTES] ____cacheline_aligned;
+	struct spi_message msg;
+
+	memset(&transfer, 0, sizeof(transfer));
+
+	spi_message_init(&msg);
+
+	tx_data[0] = (field(reg, MAX3421_SPI_REG_SHIFT) |
+		      field(MAX3421_SPI_DIR_RD, MAX3421_SPI_DIR_SHIFT));
+
+	transfer.tx_buf = tx_data;
+	transfer.rx_buf = rx_data;
+	transfer.len = 2;
+
+	spi_message_add_tail(&transfer, &msg);
+	spi_sync(spi, &msg);
+
+	return rx_data[1];
+}
+
+static void
+spi_wr8(struct usb_hcd *hcd, unsigned int reg, u8 val)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct spi_transfer transfer;
+	struct spi_message msg;
+	u8 tx_data[2];
+
+	memset(&transfer, 0, sizeof(transfer));
+
+	spi_message_init(&msg);
+
+	tx_data[0] = (field(reg, MAX3421_SPI_REG_SHIFT) |
+		      field(MAX3421_SPI_DIR_WR, MAX3421_SPI_DIR_SHIFT));
+	tx_data[1] = val;
+
+	transfer.tx_buf = tx_data;
+	transfer.len = 2;
+
+	spi_message_add_tail(&transfer, &msg);
+	spi_sync(spi, &msg);
+}
+
+static void
+spi_rd_buf(struct usb_hcd *hcd, unsigned int reg, void *buf, size_t len)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct spi_transfer transfer[2];
+	struct spi_message msg;
+	u8 cmd;
+
+	memset(transfer, 0, sizeof(transfer));
+
+	spi_message_init(&msg);
+
+	cmd = (field(reg, MAX3421_SPI_REG_SHIFT) |
+	       field(MAX3421_SPI_DIR_RD, MAX3421_SPI_DIR_SHIFT));
+
+	transfer[0].tx_buf = &cmd;
+	transfer[0].len = 1;
+
+	transfer[1].rx_buf = buf;
+	transfer[1].len = len;
+
+	spi_message_add_tail(&transfer[0], &msg);
+	spi_message_add_tail(&transfer[1], &msg);
+	spi_sync(spi, &msg);
+}
+
+static void
+spi_wr_buf(struct usb_hcd *hcd, unsigned int reg, void *buf, size_t len)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct spi_transfer transfer[2];
+	struct spi_message msg;
+	u8 cmd;
+
+	memset(transfer, 0, sizeof(transfer));
+
+	spi_message_init(&msg);
+
+	cmd = (field(reg, MAX3421_SPI_REG_SHIFT) |
+	       field(MAX3421_SPI_DIR_WR, MAX3421_SPI_DIR_SHIFT));
+
+	transfer[0].tx_buf = &cmd;
+	transfer[0].len = 1;
+
+	transfer[1].tx_buf = buf;
+	transfer[1].len = len;
+
+	spi_message_add_tail(&transfer[0], &msg);
+	spi_message_add_tail(&transfer[1], &msg);
+	spi_sync(spi, &msg);
+}
+
+/*
+ * Figure out the correct setting for the LOWSPEED and HUBPRE mode
+ * bits.  The HUBPRE bit needs to be set when MAX3421E operates at
+ * full speed, but it's talking to a low-speed device (i.e., through a
+ * hub).  Setting that bit ensures that every low-speed packet is
+ * preceded by a full-speed PRE PID.  Possible configurations:
+ *
+ * Hub speed:	Device speed:	=>	LOWSPEED bit:	HUBPRE bit:
+ *	FULL	FULL		=>	0		0
+ *	FULL	LOW		=>	1		1
+ *	LOW	LOW		=>	1		0
+ *	LOW	FULL		=>	1		0
+ */
+static void
+max3421_set_speed(struct usb_hcd *hcd, struct usb_device *dev)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	u8 mode_lowspeed, mode_hubpre, mode = max3421_hcd->mode;
+
+	mode_lowspeed = BIT(MAX3421_MODE_LOWSPEED_BIT);
+	mode_hubpre   = BIT(MAX3421_MODE_HUBPRE_BIT);
+	if (max3421_hcd->port_status & USB_PORT_STAT_LOW_SPEED) {
+		mode |=  mode_lowspeed;
+		mode &= ~mode_hubpre;
+	} else if (dev->speed == USB_SPEED_LOW) {
+		mode |= mode_lowspeed | mode_hubpre;
+	} else {
+		mode &= ~(mode_lowspeed | mode_hubpre);
+	}
+	if (mode != max3421_hcd->mode) {
+		max3421_hcd->mode = mode;
+		spi_wr8(hcd, MAX3421_REG_MODE, max3421_hcd->mode);
+	}
+
+}
+
+/*
+ * Caller must NOT hold HCD spinlock.
+ */
+static void
+max3421_set_address(struct usb_hcd *hcd, struct usb_device *dev, int epnum,
+		    int force_toggles)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	int old_epnum, same_ep, rcvtog, sndtog;
+	struct usb_device *old_dev;
+	u8 hctl;
+
+	old_dev = max3421_hcd->loaded_dev;
+	old_epnum = max3421_hcd->loaded_epnum;
+
+	same_ep = (dev == old_dev && epnum == old_epnum);
+	if (same_ep && !force_toggles)
+		return;
+
+	if (old_dev && !same_ep) {
+		/* save the old end-points toggles: */
+		u8 hrsl = spi_rd8(hcd, MAX3421_REG_HRSL);
+
+		rcvtog = (hrsl >> MAX3421_HRSL_RCVTOGRD_BIT) & 1;
+		sndtog = (hrsl >> MAX3421_HRSL_SNDTOGRD_BIT) & 1;
+
+		/* no locking: HCD (i.e., we) own toggles, don't we? */
+		usb_settoggle(old_dev, old_epnum, 0, rcvtog);
+		usb_settoggle(old_dev, old_epnum, 1, sndtog);
+	}
+	/* setup new endpoint's toggle bits: */
+	rcvtog = usb_gettoggle(dev, epnum, 0);
+	sndtog = usb_gettoggle(dev, epnum, 1);
+	hctl = (BIT(rcvtog + MAX3421_HCTL_RCVTOG0_BIT) |
+		BIT(sndtog + MAX3421_HCTL_SNDTOG0_BIT));
+
+	max3421_hcd->loaded_epnum = epnum;
+	spi_wr8(hcd, MAX3421_REG_HCTL, hctl);
+
+	/*
+	 * Note: devnum for one and the same device can change during
+	 * address-assignment so it's best to just always load the
+	 * address whenever the end-point changed/was forced.
+	 */
+	max3421_hcd->loaded_dev = dev;
+	spi_wr8(hcd, MAX3421_REG_PERADDR, dev->devnum);
+}
+
+static int
+max3421_ctrl_setup(struct usb_hcd *hcd, struct urb *urb)
+{
+	spi_wr_buf(hcd, MAX3421_REG_SUDFIFO, urb->setup_packet, 8);
+	return MAX3421_HXFR_SETUP;
+}
+
+static int
+max3421_transfer_in(struct usb_hcd *hcd, struct urb *urb)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	int epnum = usb_pipeendpoint(urb->pipe);
+
+	max3421_hcd->curr_len = 0;
+	max3421_hcd->hien |= BIT(MAX3421_HI_RCVDAV_BIT);
+	return MAX3421_HXFR_BULK_IN(epnum);
+}
+
+static int
+max3421_transfer_out(struct usb_hcd *hcd, struct urb *urb, int fast_retransmit)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	int epnum = usb_pipeendpoint(urb->pipe);
+	u32 max_packet;
+	void *src;
+
+	src = urb->transfer_buffer + urb->actual_length;
+
+	if (fast_retransmit) {
+		if (max3421_hcd->rev == 0x12) {
+			/* work around rev 0x12 bug: */
+			spi_wr8(hcd, MAX3421_REG_SNDBC, 0);
+			spi_wr8(hcd, MAX3421_REG_SNDFIFO, ((u8 *) src)[0]);
+			spi_wr8(hcd, MAX3421_REG_SNDBC, max3421_hcd->curr_len);
+		}
+		return MAX3421_HXFR_BULK_OUT(epnum);
+	}
+
+	max_packet = usb_maxpacket(urb->dev, urb->pipe, 1);
+
+	if (max_packet > MAX3421_FIFO_SIZE) {
+		/*
+		 * We do not support isochronous transfers at this
+		 * time.
+		 */
+		dev_err(&spi->dev,
+			"%s: packet-size of %u too big (limit is %u bytes)",
+			__func__, max_packet, MAX3421_FIFO_SIZE);
+		max3421_hcd->urb_done = -EMSGSIZE;
+		return -EMSGSIZE;
+	}
+	max3421_hcd->curr_len = min((urb->transfer_buffer_length -
+				     urb->actual_length), max_packet);
+
+	spi_wr_buf(hcd, MAX3421_REG_SNDFIFO, src, max3421_hcd->curr_len);
+	spi_wr8(hcd, MAX3421_REG_SNDBC, max3421_hcd->curr_len);
+	return MAX3421_HXFR_BULK_OUT(epnum);
+}
+
+/*
+ * Issue the next host-transfer command.
+ * Caller must NOT hold HCD spinlock.
+ */
+static void
+max3421_next_transfer(struct usb_hcd *hcd, int fast_retransmit)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	struct urb *urb = max3421_hcd->curr_urb;
+	struct max3421_ep *max3421_ep = urb->ep->hcpriv;
+	int cmd = -EINVAL;
+
+	if (!urb)
+		return;	/* nothing to do */
+
+	switch (max3421_ep->pkt_state) {
+	case PKT_STATE_SETUP:
+		cmd = max3421_ctrl_setup(hcd, urb);
+		break;
+
+	case PKT_STATE_TRANSFER:
+		if (usb_urb_dir_in(urb))
+			cmd = max3421_transfer_in(hcd, urb);
+		else
+			cmd = max3421_transfer_out(hcd, urb, fast_retransmit);
+		break;
+
+	case PKT_STATE_TERMINATE:
+		/*
+		 * IN transfers are terminated with HS_OUT token,
+		 * OUT transfers with HS_IN:
+		 */
+		if (usb_urb_dir_in(urb))
+			cmd = MAX3421_HXFR_HS_OUT;
+		else
+			cmd = MAX3421_HXFR_HS_IN;
+		break;
+	}
+
+	if (cmd < 0)
+		return;
+
+	/* issue the command and wait for host-xfer-done interrupt: */
+
+	spi_wr8(hcd, MAX3421_REG_HXFR, cmd);
+	max3421_hcd->hien |= BIT(MAX3421_HI_HXFRDN_BIT);
+}
+
+/*
+ * Find the next URB to process and start its execution.
+ *
+ * At this time, we do not anticipate ever connecting a USB hub to the
+ * MAX3421 chip, so at most USB device can be connected and we can use
+ * a simplistic scheduler: at the start of a frame, schedule all
+ * periodic transfers.  Once that is done, use the remainder of the
+ * frame to process non-periodic (bulk & control) transfers.
+ *
+ * Preconditions:
+ * o Caller must NOT hold HCD spinlock.
+ * o max3421_hcd->curr_urb MUST BE NULL.
+ * o MAX3421E chip must be idle.
+ */
+static int
+max3421_select_and_start_urb(struct usb_hcd *hcd)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	struct urb *urb, *curr_urb = NULL;
+	struct max3421_ep *max3421_ep;
+	int epnum, force_toggles = 0;
+	struct usb_host_endpoint *ep;
+	struct list_head *pos;
+	unsigned long flags;
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+
+	for (;
+	     max3421_hcd->sched_pass < SCHED_PASS_DONE;
+	     ++max3421_hcd->sched_pass)
+		list_for_each(pos, &max3421_hcd->ep_list) {
+			urb = NULL;
+			max3421_ep = container_of(pos, struct max3421_ep,
+						  ep_list);
+			ep = max3421_ep->ep;
+
+			switch (usb_endpoint_type(&ep->desc)) {
+			case USB_ENDPOINT_XFER_ISOC:
+			case USB_ENDPOINT_XFER_INT:
+				if (max3421_hcd->sched_pass !=
+				    SCHED_PASS_PERIODIC)
+					continue;
+				break;
+
+			case USB_ENDPOINT_XFER_CONTROL:
+			case USB_ENDPOINT_XFER_BULK:
+				if (max3421_hcd->sched_pass !=
+				    SCHED_PASS_NON_PERIODIC)
+					continue;
+				break;
+			}
+
+			if (list_empty(&ep->urb_list))
+				continue;	/* nothing to do */
+			urb = list_first_entry(&ep->urb_list, struct urb,
+					       urb_list);
+			if (urb->unlinked) {
+				dev_dbg(&spi->dev, "%s: URB %p unlinked=%d",
+					__func__, urb, urb->unlinked);
+				max3421_hcd->curr_urb = urb;
+				max3421_hcd->urb_done = 1;
+				spin_unlock_irqrestore(&max3421_hcd->lock,
+						       flags);
+				return 1;
+			}
+
+			switch (usb_endpoint_type(&ep->desc)) {
+			case USB_ENDPOINT_XFER_CONTROL:
+				/*
+				 * Allow one control transaction per
+				 * frame per endpoint:
+				 */
+				if (frame_diff(max3421_ep->last_active,
+					       max3421_hcd->frame_number) == 0)
+					continue;
+				break;
+
+			case USB_ENDPOINT_XFER_BULK:
+				if (max3421_ep->retransmit
+				    && (frame_diff(max3421_ep->last_active,
+						   max3421_hcd->frame_number)
+					== 0))
+					/*
+					 * We already tried this EP
+					 * during this frame and got a
+					 * NAK or error; wait for next frame
+					 */
+					continue;
+				break;
+
+			case USB_ENDPOINT_XFER_ISOC:
+			case USB_ENDPOINT_XFER_INT:
+				if (frame_diff(max3421_hcd->frame_number,
+					       max3421_ep->last_active)
+				    < urb->interval)
+					/*
+					 * We already processed this
+					 * end-point in the current
+					 * frame
+					 */
+					continue;
+				break;
+			}
+
+			/* move current ep to tail: */
+			list_move_tail(pos, &max3421_hcd->ep_list);
+			curr_urb = urb;
+			goto done;
+		}
+done:
+	if (!curr_urb) {
+		spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+		return 0;
+	}
+
+	urb = max3421_hcd->curr_urb = curr_urb;
+	epnum = usb_endpoint_num(&urb->ep->desc);
+	if (max3421_ep->retransmit)
+		/* restart (part of) a USB transaction: */
+		max3421_ep->retransmit = 0;
+	else {
+		/* start USB transaction: */
+		if (usb_endpoint_xfer_control(&ep->desc)) {
+			/*
+			 * See USB 2.0 spec section 8.6.1
+			 * Initialization via SETUP Token:
+			 */
+			usb_settoggle(urb->dev, epnum, 0, 1);
+			usb_settoggle(urb->dev, epnum, 1, 1);
+			max3421_ep->pkt_state = PKT_STATE_SETUP;
+			force_toggles = 1;
+		} else
+			max3421_ep->pkt_state = PKT_STATE_TRANSFER;
+	}
+
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+
+	max3421_ep->last_active = max3421_hcd->frame_number;
+	max3421_set_address(hcd, urb->dev, epnum, force_toggles);
+	max3421_set_speed(hcd, urb->dev);
+	max3421_next_transfer(hcd, 0);
+	return 1;
+}
+
+/*
+ * Check all endpoints for URBs that got unlinked.
+ *
+ * Caller must NOT hold HCD spinlock.
+ */
+static int
+max3421_check_unlink(struct usb_hcd *hcd)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	struct list_head *pos, *upos, *next_upos;
+	struct max3421_ep *max3421_ep;
+	struct usb_host_endpoint *ep;
+	struct urb *urb;
+	unsigned long flags;
+	int retval = 0;
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+	list_for_each(pos, &max3421_hcd->ep_list) {
+		max3421_ep = container_of(pos, struct max3421_ep, ep_list);
+		ep = max3421_ep->ep;
+		list_for_each_safe(upos, next_upos, &ep->urb_list) {
+			urb = container_of(upos, struct urb, urb_list);
+			if (urb->unlinked) {
+				retval = 1;
+				dev_dbg(&spi->dev, "%s: URB %p unlinked=%d",
+					__func__, urb, urb->unlinked);
+				usb_hcd_unlink_urb_from_ep(hcd, urb);
+				spin_unlock_irqrestore(&max3421_hcd->lock,
+						       flags);
+				usb_hcd_giveback_urb(hcd, urb, 0);
+				spin_lock_irqsave(&max3421_hcd->lock, flags);
+			}
+		}
+	}
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+	return retval;
+}
+
+/*
+ * Caller must NOT hold HCD spinlock.
+ */
+static void
+max3421_slow_retransmit(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	struct urb *urb = max3421_hcd->curr_urb;
+	struct max3421_ep *max3421_ep;
+
+	max3421_ep = urb->ep->hcpriv;
+	max3421_ep->retransmit = 1;
+	max3421_hcd->curr_urb = NULL;
+}
+
+/*
+ * Caller must NOT hold HCD spinlock.
+ */
+static void
+max3421_recv_data_available(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	struct urb *urb = max3421_hcd->curr_urb;
+	size_t remaining, transfer_size;
+	u8 rcvbc;
+
+	rcvbc = spi_rd8(hcd, MAX3421_REG_RCVBC);
+
+	if (rcvbc > MAX3421_FIFO_SIZE)
+		rcvbc = MAX3421_FIFO_SIZE;
+	if (urb->actual_length >= urb->transfer_buffer_length)
+		remaining = 0;
+	else
+		remaining = urb->transfer_buffer_length - urb->actual_length;
+	transfer_size = rcvbc;
+	if (transfer_size > remaining)
+		transfer_size = remaining;
+	if (transfer_size > 0) {
+		void *dst = urb->transfer_buffer + urb->actual_length;
+
+		spi_rd_buf(hcd, MAX3421_REG_RCVFIFO, dst, transfer_size);
+		urb->actual_length += transfer_size;
+		max3421_hcd->curr_len = transfer_size;
+	}
+
+	/* ack the RCVDAV irq now that the FIFO has been read: */
+	spi_wr8(hcd, MAX3421_REG_HIRQ, BIT(MAX3421_HI_RCVDAV_BIT));
+}
+
+static void
+max3421_handle_error(struct usb_hcd *hcd, u8 hrsl)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	u8 result_code = hrsl & MAX3421_HRSL_RESULT_MASK;
+	struct urb *urb = max3421_hcd->curr_urb;
+	struct max3421_ep *max3421_ep = urb->ep->hcpriv;
+	int switch_sndfifo;
+
+	/*
+	 * If an OUT command results in any response other than OK
+	 * (i.e., error or NAK), we have to perform a dummy-write to
+	 * SNDBC so the FIFO gets switched back to us.  Otherwise, we
+	 * get out of sync with the SNDFIFO double buffer.
+	 */
+	switch_sndfifo = (max3421_ep->pkt_state == PKT_STATE_TRANSFER &&
+			  usb_urb_dir_out(urb));
+
+	switch (result_code) {
+	case MAX3421_HRSL_OK:
+		return;			/* this shouldn't happen */
+
+	case MAX3421_HRSL_WRONGPID:	/* received wrong PID */
+	case MAX3421_HRSL_BUSY:		/* SIE busy */
+	case MAX3421_HRSL_BADREQ:	/* bad val in HXFR */
+	case MAX3421_HRSL_UNDEF:	/* reserved */
+	case MAX3421_HRSL_KERR:		/* K-state instead of response */
+	case MAX3421_HRSL_JERR:		/* J-state instead of response */
+		/*
+		 * packet experienced an error that we cannot recover
+		 * from; report error
+		 */
+		max3421_hcd->urb_done = hrsl_to_error[result_code];
+		dev_dbg(&spi->dev, "%s: unexpected error HRSL=0x%02x",
+			__func__, hrsl);
+		break;
+
+	case MAX3421_HRSL_TOGERR:
+		if (usb_urb_dir_in(urb))
+			; /* don't do anything (device will switch toggle) */
+		else {
+			/* flip the send toggle bit: */
+			int sndtog = (hrsl >> MAX3421_HRSL_SNDTOGRD_BIT) & 1;
+
+			sndtog ^= 1;
+			spi_wr8(hcd, MAX3421_REG_HCTL,
+				BIT(sndtog + MAX3421_HCTL_SNDTOG0_BIT));
+		}
+		/* FALL THROUGH */
+	case MAX3421_HRSL_BADBC:	/* bad byte count */
+	case MAX3421_HRSL_PIDERR:	/* received PID is corrupted */
+	case MAX3421_HRSL_PKTERR:	/* packet error (stuff, EOP) */
+	case MAX3421_HRSL_CRCERR:	/* CRC error */
+	case MAX3421_HRSL_BABBLE:	/* device talked too long */
+	case MAX3421_HRSL_TIMEOUT:
+		if (max3421_ep->retries++ < USB_MAX_RETRIES)
+			/* retry the packet again in the next frame */
+			max3421_slow_retransmit(hcd);
+		else {
+			/* Based on ohci.h cc_to_err[]: */
+			max3421_hcd->urb_done = hrsl_to_error[result_code];
+			dev_dbg(&spi->dev, "%s: unexpected error HRSL=0x%02x",
+				__func__, hrsl);
+		}
+		break;
+
+	case MAX3421_HRSL_STALL:
+		dev_dbg(&spi->dev, "%s: unexpected error HRSL=0x%02x",
+			__func__, hrsl);
+		max3421_hcd->urb_done = hrsl_to_error[result_code];
+		break;
+
+	case MAX3421_HRSL_NAK:
+		/*
+		 * Device wasn't ready for data or has no data
+		 * available: retry the packet again.
+		 */
+		if (max3421_ep->naks++ < NAK_MAX_FAST_RETRANSMITS) {
+			max3421_next_transfer(hcd, 1);
+			switch_sndfifo = 0;
+		} else
+			max3421_slow_retransmit(hcd);
+		break;
+	}
+	if (switch_sndfifo)
+		spi_wr8(hcd, MAX3421_REG_SNDBC, 0);
+}
+
+/*
+ * Caller must NOT hold HCD spinlock.
+ */
+static int
+max3421_transfer_in_done(struct usb_hcd *hcd, struct urb *urb)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	u32 max_packet;
+
+	if (urb->actual_length >= urb->transfer_buffer_length)
+		return 1;	/* read is complete, so we're done */
+
+	/*
+	 * USB 2.0 Section 5.3.2 Pipes: packets must be full size
+	 * except for last one.
+	 */
+	max_packet = usb_maxpacket(urb->dev, urb->pipe, 0);
+	if (max_packet > MAX3421_FIFO_SIZE) {
+		/*
+		 * We do not support isochronous transfers at this
+		 * time...
+		 */
+		dev_err(&spi->dev,
+			"%s: packet-size of %u too big (limit is %u bytes)",
+			__func__, max_packet, MAX3421_FIFO_SIZE);
+		return -EINVAL;
+	}
+
+	if (max3421_hcd->curr_len < max_packet) {
+		if (urb->transfer_flags & URB_SHORT_NOT_OK) {
+			/*
+			 * remaining > 0 and received an
+			 * unexpected partial packet ->
+			 * error
+			 */
+			return -EREMOTEIO;
+		} else
+			/* short read, but it's OK */
+			return 1;
+	}
+	return 0;	/* not done */
+}
+
+/*
+ * Caller must NOT hold HCD spinlock.
+ */
+static int
+max3421_transfer_out_done(struct usb_hcd *hcd, struct urb *urb)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+
+	urb->actual_length += max3421_hcd->curr_len;
+	if (urb->actual_length < urb->transfer_buffer_length)
+		return 0;
+	if (urb->transfer_flags & URB_ZERO_PACKET) {
+		/*
+		 * Some hardware needs a zero-size packet at the end
+		 * of a bulk-out transfer if the last transfer was a
+		 * full-sized packet (i.e., such hardware use <
+		 * max_packet as an indicator that the end of the
+		 * packet has been reached).
+		 */
+		u32 max_packet = usb_maxpacket(urb->dev, urb->pipe, 1);
+
+		if (max3421_hcd->curr_len == max_packet)
+			return 0;
+	}
+	return 1;
+}
+
+/*
+ * Caller must NOT hold HCD spinlock.
+ */
+static void
+max3421_host_transfer_done(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	struct urb *urb = max3421_hcd->curr_urb;
+	struct max3421_ep *max3421_ep;
+	u8 result_code, hrsl;
+	int urb_done = 0;
+
+	max3421_hcd->hien &= ~(BIT(MAX3421_HI_HXFRDN_BIT) |
+			       BIT(MAX3421_HI_RCVDAV_BIT));
+
+	hrsl = spi_rd8(hcd, MAX3421_REG_HRSL);
+	result_code = hrsl & MAX3421_HRSL_RESULT_MASK;
+
+#ifdef DEBUG
+	++max3421_hcd->err_stat[result_code];
+#endif
+
+	max3421_ep = urb->ep->hcpriv;
+
+	if (unlikely(result_code != MAX3421_HRSL_OK)) {
+		max3421_handle_error(hcd, hrsl);
+		return;
+	}
+
+	max3421_ep->naks = 0;
+	max3421_ep->retries = 0;
+	switch (max3421_ep->pkt_state) {
+
+	case PKT_STATE_SETUP:
+		if (urb->transfer_buffer_length > 0)
+			max3421_ep->pkt_state = PKT_STATE_TRANSFER;
+		else
+			max3421_ep->pkt_state = PKT_STATE_TERMINATE;
+		break;
+
+	case PKT_STATE_TRANSFER:
+		if (usb_urb_dir_in(urb))
+			urb_done = max3421_transfer_in_done(hcd, urb);
+		else
+			urb_done = max3421_transfer_out_done(hcd, urb);
+		if (urb_done > 0 && usb_pipetype(urb->pipe) == PIPE_CONTROL) {
+			/*
+			 * We aren't really done - we still need to
+			 * terminate the control transfer:
+			 */
+			max3421_hcd->urb_done = urb_done = 0;
+			max3421_ep->pkt_state = PKT_STATE_TERMINATE;
+		}
+		break;
+
+	case PKT_STATE_TERMINATE:
+		urb_done = 1;
+		break;
+	}
+
+	if (urb_done)
+		max3421_hcd->urb_done = urb_done;
+	else
+		max3421_next_transfer(hcd, 0);
+}
+
+/*
+ * Caller must NOT hold HCD spinlock.
+ */
+static void
+max3421_detect_conn(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	unsigned int jk, have_conn = 0;
+	u32 old_port_status, chg;
+	unsigned long flags;
+	u8 hrsl, mode;
+
+	hrsl = spi_rd8(hcd, MAX3421_REG_HRSL);
+
+	jk = ((((hrsl >> MAX3421_HRSL_JSTATUS_BIT) & 1) << 0) |
+	      (((hrsl >> MAX3421_HRSL_KSTATUS_BIT) & 1) << 1));
+
+	mode = max3421_hcd->mode;
+
+	switch (jk) {
+	case 0x0: /* SE0: disconnect */
+		/*
+		 * Turn off SOFKAENAB bit to avoid getting interrupt
+		 * every milli-second:
+		 */
+		mode &= ~BIT(MAX3421_MODE_SOFKAENAB_BIT);
+		break;
+
+	case 0x1: /* J=0,K=1: low-speed (in full-speed or vice versa) */
+	case 0x2: /* J=1,K=0: full-speed (in full-speed or vice versa) */
+		if (jk == 0x2)
+			/* need to switch to the other speed: */
+			mode ^= BIT(MAX3421_MODE_LOWSPEED_BIT);
+		/* turn on SOFKAENAB bit: */
+		mode |= BIT(MAX3421_MODE_SOFKAENAB_BIT);
+		have_conn = 1;
+		break;
+
+	case 0x3: /* illegal */
+		break;
+	}
+
+	max3421_hcd->mode = mode;
+	spi_wr8(hcd, MAX3421_REG_MODE, max3421_hcd->mode);
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+	old_port_status = max3421_hcd->port_status;
+	if (have_conn)
+		max3421_hcd->port_status |=  USB_PORT_STAT_CONNECTION;
+	else
+		max3421_hcd->port_status &= ~USB_PORT_STAT_CONNECTION;
+	if (mode & BIT(MAX3421_MODE_LOWSPEED_BIT))
+		max3421_hcd->port_status |=  USB_PORT_STAT_LOW_SPEED;
+	else
+		max3421_hcd->port_status &= ~USB_PORT_STAT_LOW_SPEED;
+	chg = (old_port_status ^ max3421_hcd->port_status);
+	max3421_hcd->port_status |= chg << 16;
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+}
+
+static irqreturn_t
+max3421_irq_handler(int irq, void *dev_id)
+{
+	struct usb_hcd *hcd = dev_id;
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+
+	if (max3421_hcd->spi_thread &&
+	    max3421_hcd->spi_thread->state != TASK_RUNNING)
+		wake_up_process(max3421_hcd->spi_thread);
+	if (!max3421_hcd->do_enable_irq) {
+		max3421_hcd->do_enable_irq = 1;
+		disable_irq_nosync(spi->irq);
+	}
+	return IRQ_HANDLED;
+}
+
+#ifdef DEBUG
+
+static void
+dump_eps(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	struct max3421_ep *max3421_ep;
+	struct usb_host_endpoint *ep;
+	struct list_head *pos, *upos;
+	char ubuf[512], *dp, *end;
+	unsigned long flags;
+	struct urb *urb;
+	int epnum, ret;
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+	list_for_each(pos, &max3421_hcd->ep_list) {
+		max3421_ep = container_of(pos, struct max3421_ep, ep_list);
+		ep = max3421_ep->ep;
+
+		dp = ubuf;
+		end = dp + sizeof(ubuf);
+		*dp = '\0';
+		list_for_each(upos, &ep->urb_list) {
+			urb = container_of(upos, struct urb, urb_list);
+			ret = snprintf(dp, end - dp, " %p(%d.%s %d/%d)", urb,
+				       usb_pipetype(urb->pipe),
+				       usb_urb_dir_in(urb) ? "IN" : "OUT",
+				       urb->actual_length,
+				       urb->transfer_buffer_length);
+			if (ret < 0 || ret >= end - dp)
+				break;	/* error or buffer full */
+			dp += ret;
+		}
+
+		epnum = usb_endpoint_num(&ep->desc);
+		pr_info("EP%0u %u lst %04u rtr %u nak %6u rxmt %u: %s\n",
+			epnum, max3421_ep->pkt_state, max3421_ep->last_active,
+			max3421_ep->retries, max3421_ep->naks,
+			max3421_ep->retransmit, ubuf);
+	}
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+}
+
+#endif /* DEBUG */
+
+/* Return zero if no work was performed, 1 otherwise.  */
+static int
+max3421_handle_irqs(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	u32 chg, old_port_status;
+	unsigned long flags;
+	u8 hirq;
+
+	/*
+	 * Read and ack pending interrupts (CPU must never
+	 * clear SNDBAV directly and RCVDAV must be cleared by
+	 * max3421_recv_data_available()!):
+	 */
+	hirq = spi_rd8(hcd, MAX3421_REG_HIRQ);
+	hirq &= max3421_hcd->hien;
+	if (!hirq)
+		return 0;
+
+	spi_wr8(hcd, MAX3421_REG_HIRQ,
+		hirq & ~(BIT(MAX3421_HI_SNDBAV_BIT) |
+			 BIT(MAX3421_HI_RCVDAV_BIT)));
+
+	if (hirq & BIT(MAX3421_HI_FRAME_BIT)) {
+		max3421_hcd->frame_number = ((max3421_hcd->frame_number + 1)
+					     & USB_MAX_FRAME_NUMBER);
+		max3421_hcd->sched_pass = SCHED_PASS_PERIODIC;
+	}
+
+	if (hirq & BIT(MAX3421_HI_RCVDAV_BIT))
+		max3421_recv_data_available(hcd);
+
+	if (hirq & BIT(MAX3421_HI_HXFRDN_BIT))
+		max3421_host_transfer_done(hcd);
+
+	if (hirq & BIT(MAX3421_HI_CONDET_BIT))
+		max3421_detect_conn(hcd);
+
+	/*
+	 * Now process interrupts that may affect HCD state
+	 * other than the end-points:
+	 */
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+
+	old_port_status = max3421_hcd->port_status;
+	if (hirq & BIT(MAX3421_HI_BUSEVENT_BIT)) {
+		if (max3421_hcd->port_status & USB_PORT_STAT_RESET) {
+			/* BUSEVENT due to completion of Bus Reset */
+			max3421_hcd->port_status &= ~USB_PORT_STAT_RESET;
+			max3421_hcd->port_status |=  USB_PORT_STAT_ENABLE;
+		} else {
+			/* BUSEVENT due to completion of Bus Resume */
+			pr_info("%s: BUSEVENT Bus Resume Done\n", __func__);
+		}
+	}
+	if (hirq & BIT(MAX3421_HI_RWU_BIT))
+		pr_info("%s: RWU\n", __func__);
+	if (hirq & BIT(MAX3421_HI_SUSDN_BIT))
+		pr_info("%s: SUSDN\n", __func__);
+
+	chg = (old_port_status ^ max3421_hcd->port_status);
+	max3421_hcd->port_status |= chg << 16;
+
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+
+#ifdef DEBUG
+	{
+		static unsigned long last_time;
+		char sbuf[16 * 16], *dp, *end;
+		int i;
+
+		if (jiffies - last_time > 5*HZ) {
+			dp = sbuf;
+			end = sbuf + sizeof(sbuf);
+			*dp = '\0';
+			for (i = 0; i < 16; ++i) {
+				int ret = snprintf(dp, end - dp, " %lu",
+						   max3421_hcd->err_stat[i]);
+				if (ret < 0 || ret >= end - dp)
+					break;	/* error or buffer full */
+				dp += ret;
+			}
+			pr_info("%s: hrsl_stats %s\n", __func__, sbuf);
+			memset(max3421_hcd->err_stat, 0,
+			       sizeof(max3421_hcd->err_stat));
+			last_time = jiffies;
+
+			dump_eps(hcd);
+		}
+	}
+#endif
+	return 1;
+}
+
+static int
+max3421_reset_hcd(struct usb_hcd *hcd)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	int timeout;
+
+	/* perform a chip reset and wait for OSCIRQ signal to appear: */
+	spi_wr8(hcd, MAX3421_REG_USBCTL, BIT(MAX3421_USBCTL_CHIPRES_BIT));
+	/* clear reset: */
+	spi_wr8(hcd, MAX3421_REG_USBCTL, 0);
+	timeout = 1000;
+	while (1) {
+		if (spi_rd8(hcd, MAX3421_REG_USBIRQ)
+		    & BIT(MAX3421_USBIRQ_OSCOKIRQ_BIT))
+			break;
+		if (--timeout < 0) {
+			dev_err(&spi->dev,
+				"timed out waiting for oscillator OK signal");
+			return 1;
+		}
+		cond_resched();
+	}
+
+	/*
+	 * Turn on host mode, automatic generation of SOF packets, and
+	 * enable pull-down registers on DM/DP:
+	 */
+	max3421_hcd->mode = (BIT(MAX3421_MODE_HOST_BIT) |
+			     BIT(MAX3421_MODE_SOFKAENAB_BIT) |
+			     BIT(MAX3421_MODE_DMPULLDN_BIT) |
+			     BIT(MAX3421_MODE_DPPULLDN_BIT));
+	spi_wr8(hcd, MAX3421_REG_MODE, max3421_hcd->mode);
+
+	/* reset frame-number: */
+	max3421_hcd->frame_number = USB_MAX_FRAME_NUMBER;
+	spi_wr8(hcd, MAX3421_REG_HCTL, BIT(MAX3421_HCTL_FRMRST_BIT));
+
+	/* sample the state of the D+ and D- lines */
+	spi_wr8(hcd, MAX3421_REG_HCTL, BIT(MAX3421_HCTL_SAMPLEBUS_BIT));
+	max3421_detect_conn(hcd);
+
+	/* enable frame, connection-detected, and bus-event interrupts: */
+	max3421_hcd->hien = (BIT(MAX3421_HI_FRAME_BIT) |
+			     BIT(MAX3421_HI_CONDET_BIT) |
+			     BIT(MAX3421_HI_BUSEVENT_BIT));
+	spi_wr8(hcd, MAX3421_REG_HIEN, max3421_hcd->hien);
+
+	/* enable interrupts: */
+	spi_wr8(hcd, MAX3421_REG_CPUCTL, BIT(MAX3421_CPUCTL_IE_BIT));
+	return 1;
+}
+
+static int
+max3421_urb_done(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	unsigned long flags;
+	struct urb *urb;
+	int status;
+
+	status = max3421_hcd->urb_done;
+	max3421_hcd->urb_done = 0;
+	if (status > 0)
+		status = 0;
+	urb = max3421_hcd->curr_urb;
+	if (urb) {
+		max3421_hcd->curr_urb = NULL;
+		spin_lock_irqsave(&max3421_hcd->lock, flags);
+		usb_hcd_unlink_urb_from_ep(hcd, urb);
+		spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+
+		/* must be called without the HCD spinlock: */
+		usb_hcd_giveback_urb(hcd, urb, status);
+	}
+	return 1;
+}
+
+static int
+max3421_spi_thread(void *dev_id)
+{
+	struct usb_hcd *hcd = dev_id;
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	int i, i_worked = 1;
+
+	/* set full-duplex SPI mode, low-active interrupt pin: */
+	spi_wr8(hcd, MAX3421_REG_PINCTL,
+		(BIT(MAX3421_PINCTL_FDUPSPI_BIT) |	/* full-duplex */
+		 BIT(MAX3421_PINCTL_INTLEVEL_BIT)));	/* low-active irq */
+
+	while (!kthread_should_stop()) {
+		max3421_hcd->rev = spi_rd8(hcd, MAX3421_REG_REVISION);
+		if (max3421_hcd->rev == 0x12 || max3421_hcd->rev == 0x13)
+			break;
+		dev_err(&spi->dev, "bad rev 0x%02x", max3421_hcd->rev);
+		msleep(10000);
+	}
+	dev_info(&spi->dev, "rev 0x%x, SPI clk %dHz, bpw %u, irq %d\n",
+		 max3421_hcd->rev, spi->max_speed_hz, spi->bits_per_word,
+		 spi->irq);
+
+	while (!kthread_should_stop()) {
+		if (!i_worked) {
+			/*
+			 * We'll be waiting for wakeups from the hard
+			 * interrupt handler, so now is a good time to
+			 * sync our hien with the chip:
+			 */
+			spi_wr8(hcd, MAX3421_REG_HIEN, max3421_hcd->hien);
+
+			set_current_state(TASK_INTERRUPTIBLE);
+			if (max3421_hcd->do_enable_irq) {
+				max3421_hcd->do_enable_irq = 0;
+				enable_irq(spi->irq);
+			}
+			schedule();
+			__set_current_state(TASK_RUNNING);
+		}
+
+		i_worked = 0;
+
+		if (max3421_hcd->urb_done)
+			i_worked |= max3421_urb_done(hcd);
+		else if (max3421_handle_irqs(hcd))
+			i_worked = 1;
+		else if (!max3421_hcd->curr_urb)
+			i_worked |= max3421_select_and_start_urb(hcd);
+
+		if (max3421_hcd->do_reset_hcd) {
+			/* reset the HCD: */
+			max3421_hcd->do_reset_hcd = 0;
+			i_worked |= max3421_reset_hcd(hcd);
+		}
+		if (max3421_hcd->do_reset_port) {
+			/* perform a USB bus reset: */
+			max3421_hcd->do_reset_port = 0;
+			spi_wr8(hcd, MAX3421_REG_HCTL,
+				BIT(MAX3421_HCTL_BUSRST_BIT));
+			i_worked = 1;
+		}
+		if (max3421_hcd->do_check_unlink) {
+			max3421_hcd->do_check_unlink = 0;
+			i_worked |= max3421_check_unlink(hcd);
+		}
+		if (max3421_hcd->do_iopin_update) {
+			/*
+			 * IOPINS1/IOPINS2 do not auto-increment, so we can't
+			 * use spi_wr_buf().
+			 */
+			for (i = 0; i < ARRAY_SIZE(max3421_hcd->iopins); ++i) {
+				u8 val = spi_rd8(hcd, MAX3421_REG_IOPINS1);
+
+				val = ((val & 0xf0) |
+				       (max3421_hcd->iopins[i] & 0x0f));
+				spi_wr8(hcd, MAX3421_REG_IOPINS1 + i, val);
+				max3421_hcd->iopins[i] = val;
+			}
+			max3421_hcd->do_iopin_update = 0;
+			i_worked = 1;
+		}
+	}
+	set_current_state(TASK_RUNNING);
+	dev_info(&spi->dev, "SPI thread exiting");
+	return 0;
+}
+
+static int
+max3421_reset_port(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+
+	max3421_hcd->port_status &= ~(USB_PORT_STAT_ENABLE |
+				      USB_PORT_STAT_LOW_SPEED);
+	max3421_hcd->do_reset_port = 1;
+	wake_up_process(max3421_hcd->spi_thread);
+	return 0;
+}
+
+static int
+max3421_reset(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+
+	hcd->self.sg_tablesize = 0;
+	hcd->speed = HCD_USB2;
+	hcd->self.root_hub->speed = USB_SPEED_FULL;
+	max3421_hcd->do_reset_hcd = 1;
+	wake_up_process(max3421_hcd->spi_thread);
+	return 0;
+}
+
+static int
+max3421_start(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+
+	spin_lock_init(&max3421_hcd->lock);
+	max3421_hcd->rh_state = MAX3421_RH_RUNNING;
+
+	INIT_LIST_HEAD(&max3421_hcd->ep_list);
+
+	hcd->power_budget = POWER_BUDGET;
+	hcd->state = HC_STATE_RUNNING;
+	hcd->uses_new_polling = 1;
+	return 0;
+}
+
+static void
+max3421_stop(struct usb_hcd *hcd)
+{
+}
+
+static int
+max3421_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	struct max3421_ep *max3421_ep;
+	unsigned long flags;
+	int retval;
+
+	switch (usb_pipetype(urb->pipe)) {
+	case PIPE_INTERRUPT:
+	case PIPE_ISOCHRONOUS:
+		if (urb->interval < 0) {
+			dev_err(&spi->dev,
+			  "%s: interval=%d for intr-/iso-pipe; expected > 0\n",
+				__func__, urb->interval);
+			return -EINVAL;
+		}
+	default:
+		break;
+	}
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+
+	max3421_ep = urb->ep->hcpriv;
+	if (!max3421_ep) {
+		/* gets freed in max3421_endpoint_disable: */
+		max3421_ep = kzalloc(sizeof(struct max3421_ep), mem_flags);
+		if (!max3421_ep)
+			return -ENOMEM;
+		max3421_ep->ep = urb->ep;
+		max3421_ep->last_active = max3421_hcd->frame_number;
+		urb->ep->hcpriv = max3421_ep;
+
+		list_add_tail(&max3421_ep->ep_list, &max3421_hcd->ep_list);
+	}
+
+	retval = usb_hcd_link_urb_to_ep(hcd, urb);
+	if (retval == 0) {
+		/* Since we added to the queue, restart scheduling: */
+		max3421_hcd->sched_pass = SCHED_PASS_PERIODIC;
+		wake_up_process(max3421_hcd->spi_thread);
+	}
+
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+	return retval;
+}
+
+static int
+max3421_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	unsigned long flags;
+	int retval;
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+
+	/*
+	 * This will set urb->unlinked which in turn causes the entry
+	 * to be dropped at the next opportunity.
+	 */
+	retval = usb_hcd_check_unlink_urb(hcd, urb, status);
+	if (retval == 0) {
+		max3421_hcd->do_check_unlink = 1;
+		wake_up_process(max3421_hcd->spi_thread);
+	}
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+	return retval;
+}
+
+static void
+max3421_endpoint_disable(struct usb_hcd *hcd, struct usb_host_endpoint *ep)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	unsigned long flags;
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+
+	if (ep->hcpriv) {
+		struct max3421_ep *max3421_ep = ep->hcpriv;
+
+		/* remove myself from the ep_list: */
+		if (!list_empty(&max3421_ep->ep_list))
+			list_del(&max3421_ep->ep_list);
+		kfree(max3421_ep);
+		ep->hcpriv = NULL;
+	}
+
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+}
+
+static int
+max3421_get_frame_number(struct usb_hcd *hcd)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	return max3421_hcd->frame_number;
+}
+
+/*
+ * Should return a non-zero value when any port is undergoing a resume
+ * transition while the root hub is suspended.
+ */
+static int
+max3421_hub_status_data(struct usb_hcd *hcd, char *buf)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	unsigned long flags;
+	int retval = 0;
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+	if (!HCD_HW_ACCESSIBLE(hcd))
+		goto done;
+
+	*buf = 0;
+	if ((max3421_hcd->port_status & PORT_C_MASK) != 0) {
+		*buf = (1 << 1); /* a hub over-current condition exists */
+		dev_dbg(hcd->self.controller,
+			"port status 0x%08x has changes\n",
+			max3421_hcd->port_status);
+		retval = 1;
+		if (max3421_hcd->rh_state == MAX3421_RH_SUSPENDED)
+			usb_hcd_resume_root_hub(hcd);
+	}
+done:
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+	return retval;
+}
+
+static inline void
+hub_descriptor(struct usb_hub_descriptor *desc)
+{
+	memset(desc, 0, sizeof(*desc));
+	/*
+	 * See Table 11-13: Hub Descriptor in USB 2.0 spec.
+	 */
+	desc->bDescriptorType = 0x29;	/* hub descriptor */
+	desc->bDescLength = 9;
+	desc->wHubCharacteristics = cpu_to_le16(0x0001);
+	desc->bNbrPorts = 1;
+}
+
+/*
+ * Set the MAX3421E general-purpose output with number PIN_NUMBER to
+ * VALUE (0 or 1).  PIN_NUMBER may be in the range from 1-8.  For
+ * any other value, this function acts as a no-op.
+ */
+static void
+max3421_gpout_set_value(struct usb_hcd *hcd, u8 pin_number, u8 value)
+{
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	u8 mask, idx;
+
+	--pin_number;
+	if (pin_number > 7)
+		return;
+
+	mask = 1u << pin_number;
+	idx = pin_number / 4;
+
+	if (value)
+		max3421_hcd->iopins[idx] |=  mask;
+	else
+		max3421_hcd->iopins[idx] &= ~mask;
+	max3421_hcd->do_iopin_update = 1;
+	wake_up_process(max3421_hcd->spi_thread);
+}
+
+static int
+max3421_hub_control(struct usb_hcd *hcd, u16 type_req, u16 value, u16 index,
+		    char *buf, u16 length)
+{
+	struct spi_device *spi = to_spi_device(hcd->self.controller);
+	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
+	struct max3421_hcd_platform_data *pdata;
+	unsigned long flags;
+	int retval = 0;
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+
+	pdata = spi->dev.platform_data;
+
+	switch (type_req) {
+	case ClearHubFeature:
+		break;
+	case ClearPortFeature:
+		switch (value) {
+		case USB_PORT_FEAT_SUSPEND:
+			break;
+		case USB_PORT_FEAT_POWER:
+			dev_dbg(hcd->self.controller, "power-off\n");
+			max3421_gpout_set_value(hcd, pdata->vbus_gpout, 0);
+			/* FALLS THROUGH */
+		default:
+			max3421_hcd->port_status &= ~(1 << value);
+		}
+		break;
+	case GetHubDescriptor:
+		hub_descriptor((struct usb_hub_descriptor *) buf);
+		break;
+
+	case DeviceRequest | USB_REQ_GET_DESCRIPTOR:
+	case GetPortErrorCount:
+	case SetHubDepth:
+		/* USB3 only */
+		goto error;
+
+	case GetHubStatus:
+		*(__le32 *) buf = cpu_to_le32(0);
+		break;
+
+	case GetPortStatus:
+		if (index != 1) {
+			retval = -EPIPE;
+			goto error;
+		}
+		((__le16 *) buf)[0] = cpu_to_le16(max3421_hcd->port_status);
+		((__le16 *) buf)[1] =
+			cpu_to_le16(max3421_hcd->port_status >> 16);
+		break;
+
+	case SetHubFeature:
+		retval = -EPIPE;
+		break;
+
+	case SetPortFeature:
+		switch (value) {
+		case USB_PORT_FEAT_LINK_STATE:
+		case USB_PORT_FEAT_U1_TIMEOUT:
+		case USB_PORT_FEAT_U2_TIMEOUT:
+		case USB_PORT_FEAT_BH_PORT_RESET:
+			goto error;
+		case USB_PORT_FEAT_SUSPEND:
+			if (max3421_hcd->active)
+				max3421_hcd->port_status |=
+					USB_PORT_STAT_SUSPEND;
+			break;
+		case USB_PORT_FEAT_POWER:
+			dev_dbg(hcd->self.controller, "power-on\n");
+			max3421_hcd->port_status |= USB_PORT_STAT_POWER;
+			max3421_gpout_set_value(hcd, pdata->vbus_gpout, 1);
+			break;
+		case USB_PORT_FEAT_RESET:
+			max3421_reset_port(hcd);
+			/* FALLS THROUGH */
+		default:
+			if ((max3421_hcd->port_status & USB_PORT_STAT_POWER)
+			    != 0)
+				max3421_hcd->port_status |= (1 << value);
+		}
+		break;
+
+	default:
+		dev_dbg(hcd->self.controller,
+			"hub control req%04x v%04x i%04x l%d\n",
+			type_req, value, index, length);
+error:		/* "protocol stall" on error */
+		retval = -EPIPE;
+	}
+
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+	return retval;
+}
+
+static int
+max3421_bus_suspend(struct usb_hcd *hcd)
+{
+	return -1;
+}
+
+static int
+max3421_bus_resume(struct usb_hcd *hcd)
+{
+	return -1;
+}
+
+/*
+ * The SPI driver already takes care of DMA-mapping/unmapping, so no
+ * reason to do it twice.
+ */
+static int
+max3421_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
+{
+	return 0;
+}
+
+static void
+max3421_unmap_urb_for_dma(struct usb_hcd *hcd, struct urb *urb)
+{
+}
+
+static struct hc_driver max3421_hcd_desc = {
+	.description =		"max3421",
+	.product_desc =		DRIVER_DESC,
+	.hcd_priv_size =	sizeof(struct max3421_hcd),
+	.flags =		HCD_USB11,
+	.reset =		max3421_reset,
+	.start =		max3421_start,
+	.stop =			max3421_stop,
+	.get_frame_number =	max3421_get_frame_number,
+	.urb_enqueue =		max3421_urb_enqueue,
+	.urb_dequeue =		max3421_urb_dequeue,
+	.map_urb_for_dma =	max3421_map_urb_for_dma,
+	.unmap_urb_for_dma =	max3421_unmap_urb_for_dma,
+	.endpoint_disable =	max3421_endpoint_disable,
+	.hub_status_data =	max3421_hub_status_data,
+	.hub_control =		max3421_hub_control,
+	.bus_suspend =		max3421_bus_suspend,
+	.bus_resume =		max3421_bus_resume,
+};
+
+static int
+max3421_probe(struct spi_device *spi)
+{
+	struct max3421_hcd *max3421_hcd;
+	struct usb_hcd *hcd;
+	int retval;
+
+	if (spi_setup(spi) < 0) {
+		dev_err(&spi->dev, "Unable to setup SPI bus");
+		return -EFAULT;
+	}
+
+	hcd = usb_create_hcd(&max3421_hcd_desc, &spi->dev,
+			     dev_name(&spi->dev));
+	if (!hcd) {
+		dev_err(&spi->dev, "failed to create HCD structure\n");
+		return -ENOMEM;
+	}
+	set_bit(HCD_FLAG_POLL_RH, &hcd->flags);
+	max3421_hcd = hcd_to_max3421(hcd);
+	max3421_hcd->next = max3421_hcd_list;
+	max3421_hcd_list = max3421_hcd;
+	INIT_LIST_HEAD(&max3421_hcd->ep_list);
+
+	max3421_hcd->spi_thread = kthread_run(max3421_spi_thread, hcd,
+					      "max3421_spi_thread");
+	if (max3421_hcd->spi_thread == ERR_PTR(-ENOMEM)) {
+		dev_err(&spi->dev,
+			"failed to create SPI thread (out of memory)\n");
+		return -ENOMEM;
+	}
+
+	retval = usb_add_hcd(hcd, 0, 0);
+	if (retval) {
+		dev_err(&spi->dev, "failed to add HCD\n");
+		usb_put_hcd(hcd);
+		return retval;
+	}
+
+	retval = request_irq(spi->irq, max3421_irq_handler,
+			     IRQF_TRIGGER_LOW, "max3421", hcd);
+	if (retval < 0) {
+		usb_put_hcd(hcd);
+		dev_err(&spi->dev, "failed to request irq %d\n", spi->irq);
+		return retval;
+	}
+	return 0;
+}
+
+static int
+max3421_remove(struct spi_device *spi)
+{
+	struct max3421_hcd *max3421_hcd = NULL, **prev;
+	struct usb_hcd *hcd = NULL;
+	unsigned long flags;
+
+	for (prev = &max3421_hcd_list; *prev; prev = &(*prev)->next) {
+		max3421_hcd = *prev;
+		hcd = max3421_to_hcd(max3421_hcd);
+		if (hcd->self.controller == &spi->dev)
+			break;
+	}
+	if (!max3421_hcd) {
+		dev_err(&spi->dev, "no MAX3421 HCD found for SPI device %p\n",
+			spi);
+		return -ENODEV;
+	}
+
+	usb_remove_hcd(hcd);
+
+	spin_lock_irqsave(&max3421_hcd->lock, flags);
+
+	kthread_stop(max3421_hcd->spi_thread);
+	*prev = max3421_hcd->next;
+
+	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
+
+	free_irq(spi->irq, hcd);
+
+	usb_put_hcd(hcd);
+	return 0;
+}
+
+static struct spi_driver max3421_driver = {
+	.probe		= max3421_probe,
+	.remove		= max3421_remove,
+	.driver		= {
+		.name	= "max3421-hcd",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init
+max3421_mod_init(void)
+{
+	return spi_register_driver(&max3421_driver);
+}
+
+static void __exit
+max3421_mod_exit(void)
+{
+	spi_unregister_driver(&max3421_driver);
+}
+
+module_init(max3421_mod_init);
+module_exit(max3421_mod_exit);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("David Mosberger <davidm@egauge.net>");
+MODULE_LICENSE("GPL");

include/linux/platform_data/max3421-hcd.h

+/*
+ * Copyright (c) 2014 eGauge Systems LLC
+ *	Contributed by David Mosberger-Tang <davidm@egauge.net>
+ *
+ * Platform-data structure for MAX3421 USB HCD driver.
+ *
+ */
+#ifndef MAX3421_HCD_PLAT_H_INCLUDED
+#define MAX3421_HCD_PLAT_H_INCLUDED
+
+/*
+ * This structure defines the mapping of certain auxiliary functions to the
+ * MAX3421E GPIO pins.  The chip has eight GP inputs and eight GP outputs.
+ * A value of 0 indicates that the pin is not used/wired to anything.
+ *
+ * At this point, the only control the max3421-hcd driver cares about is
+ * to control Vbus (5V to the peripheral).
+ */
+struct max3421_hcd_platform_data {
+	u8 vbus_gpout;			/* pin controlling Vbus */
+};
+
+#endif /* MAX3421_HCD_PLAT_H_INCLUDED */