Linux Kernel: Add support for using a MAX3421E chip as a host driver

This change "Add support for using a MAX3421E chip as a host driver." (commit 2d53139) in Linux kernel is authored by David Mosberger <davidm [at] egauge.net> on Mon Apr 28 22:14:07 2014 -0600.

Description of "Add support for using a MAX3421E chip as a host driver."

The change "Add support for using a MAX3421E chip as a host driver." introduces changes as follows.

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>

Linux kernel code changes from "Add support for using a MAX3421E chip as a host driver."

There are 1973 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/usb/Makefile                      |    1 +
 drivers/usb/host/Kconfig                  |   11 +
 drivers/usb/host/Makefile                 |    1 +
 drivers/usb/host/max3421-hcd.c            | 1937 +++++++++++++++++++++
 include/linux/platform_data/max3421-hcd.h |   23 +
 5 files changed, 1973 insertions(+)
 create mode 100644 drivers/usb/host/max3421-hcd.c
 create mode 100644 include/linux/platform_data/max3421-hcd.h

diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
index 1ae2bf39d84b..9bb672199703 100644
--- a/drivers/usb/Makefile
+++ b/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/

diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index 7a39ae86d5ce..52144c720a1d 100644
--- a/drivers/usb/host/Kconfig
+++ b/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
diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
index 7530468c9a4f..ea2bec52a4fb 100644
--- a/drivers/usb/host/Makefile
+++ b/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
diff --git a/drivers/usb/host/max3421-hcd.c b/drivers/usb/host/max3421-hcd.c
new file mode 100644
index 000000000000..dfc74d6738db
--- /dev/null
+++ b/drivers/usb/host/max3421-hcd.c
@@ -0,0 +1,1937 @@
+/*
+ * 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 = '';
+       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: %sn",
+           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 Donen", __func__);
+       }
+   }
+   if (hirq & BIT(MAX3421_HI_RWU_BIT))
+       pr_info("%s: RWUn", __func__);
+   if (hirq & BIT(MAX3421_HI_SUSDN_BIT))
+       pr_info("%s: SUSDNn", __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 = '';
+           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 %sn", __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 %dn",
+        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 > 0n",
+               __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 changesn",
+           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-offn");
+           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-onn");
+           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%dn",
+           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 structuren");
+       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 HCDn");
+       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 %dn", 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 %pn",
+           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");
diff --git a/include/linux/platform_data/max3421-hcd.h b/include/linux/platform_data/max3421-hcd.h
new file mode 100644
index 000000000000..4ad459605d87
--- /dev/null
+++ b/include/linux/platform_data/max3421-hcd.h
(patch truncated as it is too big)

The commit for this change in Linux stable tree is 2d53139 (patch).

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