uas: improve error handling

[mirror_ubuntu-zesty-kernel.git] / drivers / usb / storage / uas.c

/*
 * USB Attached SCSI
 * Note that this is not the same as the USB Mass Storage driver
 *
 * Copyright Matthew Wilcox for Intel Corp, 2010
 * Copyright Sarah Sharp for Intel Corp, 2010
 *
 * Distributed under the terms of the GNU GPL, version two.
 */

#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>
#include <linux/usb/storage.h>
#include <linux/usb/uas.h>

#include <scsi/scsi.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>

/*
 * The r00-r01c specs define this version of the SENSE IU data structure.
 * It's still in use by several different firmware releases.
 */
struct sense_iu_old {
        __u8 iu_id;
        __u8 rsvd1;
        __be16 tag;
        __be16 len;
        __u8 status;
        __u8 service_response;
        __u8 sense[SCSI_SENSE_BUFFERSIZE];
};

struct uas_dev_info {
        struct usb_interface *intf;
        struct usb_device *udev;
        int qdepth;
        unsigned cmd_pipe, status_pipe, data_in_pipe, data_out_pipe;
        unsigned use_streams:1;
        unsigned uas_sense_old:1;
        struct scsi_cmnd *cmnd;
};

enum {
        SUBMIT_STATUS_URB       = (1 << 1),
        ALLOC_DATA_IN_URB       = (1 << 2),
        SUBMIT_DATA_IN_URB      = (1 << 3),
        ALLOC_DATA_OUT_URB      = (1 << 4),
        SUBMIT_DATA_OUT_URB     = (1 << 5),
        ALLOC_CMD_URB           = (1 << 6),
        SUBMIT_CMD_URB          = (1 << 7),
        COMMAND_INFLIGHT        = (1 << 8),
        DATA_IN_URB_INFLIGHT    = (1 << 9),
        DATA_OUT_URB_INFLIGHT   = (1 << 10),
        COMMAND_COMPLETED       = (1 << 11),
};

/* Overrides scsi_pointer */
struct uas_cmd_info {
        unsigned int state;
        unsigned int stream;
        struct urb *cmd_urb;
        struct urb *data_in_urb;
        struct urb *data_out_urb;
        struct list_head list;
};

/* I hate forward declarations, but I actually have a loop */
static int uas_submit_urbs(struct scsi_cmnd *cmnd,
                                struct uas_dev_info *devinfo, gfp_t gfp);
static void uas_do_work(struct work_struct *work);

static DECLARE_WORK(uas_work, uas_do_work);
static DEFINE_SPINLOCK(uas_work_lock);
static LIST_HEAD(uas_work_list);

static void uas_do_work(struct work_struct *work)
{
        struct uas_cmd_info *cmdinfo;
        struct uas_cmd_info *temp;
        struct list_head list;
        int err;

        spin_lock_irq(&uas_work_lock);
        list_replace_init(&uas_work_list, &list);
        spin_unlock_irq(&uas_work_lock);

        list_for_each_entry_safe(cmdinfo, temp, &list, list) {
                struct scsi_pointer *scp = (void *)cmdinfo;
                struct scsi_cmnd *cmnd = container_of(scp,
                                                        struct scsi_cmnd, SCp);
                err = uas_submit_urbs(cmnd, cmnd->device->hostdata, GFP_NOIO);
                if (err) {
                        list_del(&cmdinfo->list);
                        spin_lock_irq(&uas_work_lock);
                        list_add_tail(&cmdinfo->list, &uas_work_list);
                        spin_unlock_irq(&uas_work_lock);
                        schedule_work(&uas_work);
                }
        }
}

static void uas_sense(struct urb *urb, struct scsi_cmnd *cmnd)
{
        struct sense_iu *sense_iu = urb->transfer_buffer;
        struct scsi_device *sdev = cmnd->device;

        if (urb->actual_length > 16) {
                unsigned len = be16_to_cpup(&sense_iu->len);
                if (len + 16 != urb->actual_length) {
                        int newlen = min(len + 16, urb->actual_length) - 16;
                        if (newlen < 0)
                                newlen = 0;
                        sdev_printk(KERN_INFO, sdev, "%s: urb length %d "
                                "disagrees with IU sense data length %d, "
                                "using %d bytes of sense data\n", __func__,
                                        urb->actual_length, len, newlen);
                        len = newlen;
                }
                memcpy(cmnd->sense_buffer, sense_iu->sense, len);
        }

        cmnd->result = sense_iu->status;
}

static void uas_sense_old(struct urb *urb, struct scsi_cmnd *cmnd)
{
        struct sense_iu_old *sense_iu = urb->transfer_buffer;
        struct scsi_device *sdev = cmnd->device;

        if (urb->actual_length > 8) {
                unsigned len = be16_to_cpup(&sense_iu->len) - 2;
                if (len + 8 != urb->actual_length) {
                        int newlen = min(len + 8, urb->actual_length) - 8;
                        if (newlen < 0)
                                newlen = 0;
                        sdev_printk(KERN_INFO, sdev, "%s: urb length %d "
                                "disagrees with IU sense data length %d, "
                                "using %d bytes of sense data\n", __func__,
                                        urb->actual_length, len, newlen);
                        len = newlen;
                }
                memcpy(cmnd->sense_buffer, sense_iu->sense, len);
        }

        cmnd->result = sense_iu->status;
}

static void uas_log_cmd_state(struct scsi_cmnd *cmnd, const char *caller)
{
        struct uas_cmd_info *ci = (void *)&cmnd->SCp;

        scmd_printk(KERN_INFO, cmnd, "%s %p tag %d, inflight:"
                    "%s%s%s%s%s%s%s%s%s%s%s\n",
                    caller, cmnd, cmnd->request->tag,
                    (ci->state & SUBMIT_STATUS_URB)     ? " s-st"  : "",
                    (ci->state & ALLOC_DATA_IN_URB)     ? " a-in"  : "",
                    (ci->state & SUBMIT_DATA_IN_URB)    ? " s-in"  : "",
                    (ci->state & ALLOC_DATA_OUT_URB)    ? " a-out" : "",
                    (ci->state & SUBMIT_DATA_OUT_URB)   ? " s-out" : "",
                    (ci->state & ALLOC_CMD_URB)         ? " a-cmd" : "",
                    (ci->state & SUBMIT_CMD_URB)        ? " s-cmd" : "",
                    (ci->state & COMMAND_INFLIGHT)      ? " CMD"   : "",
                    (ci->state & DATA_IN_URB_INFLIGHT)  ? " IN"    : "",
                    (ci->state & DATA_OUT_URB_INFLIGHT) ? " OUT"   : "",
                    (ci->state & COMMAND_COMPLETED)     ? " done"  : "");
}

static int uas_try_complete(struct scsi_cmnd *cmnd, const char *caller)
{
        struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;

        if (cmdinfo->state & (COMMAND_INFLIGHT |
                              DATA_IN_URB_INFLIGHT |
                              DATA_OUT_URB_INFLIGHT))
                return -EBUSY;
        BUG_ON(cmdinfo->state & COMMAND_COMPLETED);
        cmdinfo->state |= COMMAND_COMPLETED;
        usb_free_urb(cmdinfo->data_in_urb);
        usb_free_urb(cmdinfo->data_out_urb);
        cmnd->scsi_done(cmnd);
        return 0;
}

static void uas_xfer_data(struct urb *urb, struct scsi_cmnd *cmnd,
                          unsigned direction)
{
        struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
        int err;

        cmdinfo->state |= direction | SUBMIT_STATUS_URB;
        err = uas_submit_urbs(cmnd, cmnd->device->hostdata, GFP_ATOMIC);
        if (err) {
                spin_lock(&uas_work_lock);
                list_add_tail(&cmdinfo->list, &uas_work_list);
                spin_unlock(&uas_work_lock);
                schedule_work(&uas_work);
        }
}

static void uas_stat_cmplt(struct urb *urb)
{
        struct iu *iu = urb->transfer_buffer;
        struct Scsi_Host *shost = urb->context;
        struct uas_dev_info *devinfo = (void *)shost->hostdata[0];
        struct scsi_cmnd *cmnd;
        struct uas_cmd_info *cmdinfo;
        u16 tag;

        if (urb->status) {
                dev_err(&urb->dev->dev, "URB BAD STATUS %d\n", urb->status);
                usb_free_urb(urb);
                return;
        }

        tag = be16_to_cpup(&iu->tag) - 1;
        if (tag == 0)
                cmnd = devinfo->cmnd;
        else
                cmnd = scsi_host_find_tag(shost, tag - 1);
        if (!cmnd) {
                usb_free_urb(urb);
                return;
        }
        cmdinfo = (void *)&cmnd->SCp;

        switch (iu->iu_id) {
        case IU_ID_STATUS:
                if (devinfo->cmnd == cmnd)
                        devinfo->cmnd = NULL;

                if (urb->actual_length < 16)
                        devinfo->uas_sense_old = 1;
                if (devinfo->uas_sense_old)
                        uas_sense_old(urb, cmnd);
                else
                        uas_sense(urb, cmnd);
                if (cmnd->result != 0) {
                        /* cancel data transfers on error */
                        if (cmdinfo->state & DATA_IN_URB_INFLIGHT)
                                usb_unlink_urb(cmdinfo->data_in_urb);
                        if (cmdinfo->state & DATA_OUT_URB_INFLIGHT)
                                usb_unlink_urb(cmdinfo->data_out_urb);
                }
                cmdinfo->state &= ~COMMAND_INFLIGHT;
                uas_try_complete(cmnd, __func__);
                break;
        case IU_ID_READ_READY:
                uas_xfer_data(urb, cmnd, SUBMIT_DATA_IN_URB);
                break;
        case IU_ID_WRITE_READY:
                uas_xfer_data(urb, cmnd, SUBMIT_DATA_OUT_URB);
                break;
        default:
                scmd_printk(KERN_ERR, cmnd,
                        "Bogus IU (%d) received on status pipe\n", iu->iu_id);
        }
        usb_free_urb(urb);
}

static void uas_data_cmplt(struct urb *urb)
{
        struct scsi_cmnd *cmnd = urb->context;
        struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
        struct scsi_data_buffer *sdb = NULL;

        if (cmdinfo->data_in_urb == urb) {
                sdb = scsi_in(cmnd);
                cmdinfo->state &= ~DATA_IN_URB_INFLIGHT;
        } else if (cmdinfo->data_out_urb == urb) {
                sdb = scsi_out(cmnd);
                cmdinfo->state &= ~DATA_OUT_URB_INFLIGHT;
        }
        BUG_ON(sdb == NULL);
        if (urb->status) {
                /* error: no data transfered */
                sdb->resid = sdb->length;
        } else {
                sdb->resid = sdb->length - urb->actual_length;
        }
        uas_try_complete(cmnd, __func__);
}

static struct urb *uas_alloc_data_urb(struct uas_dev_info *devinfo, gfp_t gfp,
                                      unsigned int pipe, u16 stream_id,
                                      struct scsi_cmnd *cmnd,
                                      enum dma_data_direction dir)
{
        struct usb_device *udev = devinfo->udev;
        struct urb *urb = usb_alloc_urb(0, gfp);
        struct scsi_data_buffer *sdb = (dir == DMA_FROM_DEVICE)
                ? scsi_in(cmnd) : scsi_out(cmnd);

        if (!urb)
                goto out;
        usb_fill_bulk_urb(urb, udev, pipe, NULL, sdb->length,
                          uas_data_cmplt, cmnd);
        if (devinfo->use_streams)
                urb->stream_id = stream_id;
        urb->num_sgs = udev->bus->sg_tablesize ? sdb->table.nents : 0;
        urb->sg = sdb->table.sgl;
 out:
        return urb;
}

static struct urb *uas_alloc_sense_urb(struct uas_dev_info *devinfo, gfp_t gfp,
                                       struct Scsi_Host *shost, u16 stream_id)
{
        struct usb_device *udev = devinfo->udev;
        struct urb *urb = usb_alloc_urb(0, gfp);
        struct sense_iu *iu;

        if (!urb)
                goto out;

        iu = kzalloc(sizeof(*iu), gfp);
        if (!iu)
                goto free;

        usb_fill_bulk_urb(urb, udev, devinfo->status_pipe, iu, sizeof(*iu),
                                                uas_stat_cmplt, shost);
        urb->stream_id = stream_id;
        urb->transfer_flags |= URB_FREE_BUFFER;
 out:
        return urb;
 free:
        usb_free_urb(urb);
        return NULL;
}

static struct urb *uas_alloc_cmd_urb(struct uas_dev_info *devinfo, gfp_t gfp,
                                        struct scsi_cmnd *cmnd, u16 stream_id)
{
        struct usb_device *udev = devinfo->udev;
        struct scsi_device *sdev = cmnd->device;
        struct urb *urb = usb_alloc_urb(0, gfp);
        struct command_iu *iu;
        int len;

        if (!urb)
                goto out;

        len = cmnd->cmd_len - 16;
        if (len < 0)
                len = 0;
        len = ALIGN(len, 4);
        iu = kzalloc(sizeof(*iu) + len, gfp);
        if (!iu)
                goto free;

        iu->iu_id = IU_ID_COMMAND;
        if (blk_rq_tagged(cmnd->request))
                iu->tag = cpu_to_be16(cmnd->request->tag + 2);
        else
                iu->tag = cpu_to_be16(1);
        iu->prio_attr = UAS_SIMPLE_TAG;
        iu->len = len;
        int_to_scsilun(sdev->lun, &iu->lun);
        memcpy(iu->cdb, cmnd->cmnd, cmnd->cmd_len);

        usb_fill_bulk_urb(urb, udev, devinfo->cmd_pipe, iu, sizeof(*iu) + len,
                                                        usb_free_urb, NULL);
        urb->transfer_flags |= URB_FREE_BUFFER;
 out:
        return urb;
 free:
        usb_free_urb(urb);
        return NULL;
}

/*
 * Why should I request the Status IU before sending the Command IU?  Spec
 * says to, but also says the device may receive them in any order.  Seems
 * daft to me.
 */

static int uas_submit_sense_urb(struct Scsi_Host *shost,
                                gfp_t gfp, unsigned int stream)
{
        struct uas_dev_info *devinfo = (void *)shost->hostdata[0];
        struct urb *urb;

        urb = uas_alloc_sense_urb(devinfo, gfp, shost, stream);
        if (!urb)
                return SCSI_MLQUEUE_DEVICE_BUSY;
        if (usb_submit_urb(urb, gfp)) {
                shost_printk(KERN_INFO, shost,
                             "sense urb submission failure\n");
                usb_free_urb(urb);
                return SCSI_MLQUEUE_DEVICE_BUSY;
        }
        return 0;
}

static int uas_submit_urbs(struct scsi_cmnd *cmnd,
                           struct uas_dev_info *devinfo, gfp_t gfp)
{
        struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
        int err;

        if (cmdinfo->state & SUBMIT_STATUS_URB) {
                err = uas_submit_sense_urb(cmnd->device->host, gfp,
                                           cmdinfo->stream);
                if (err) {
                        return err;
                }
                cmdinfo->state &= ~SUBMIT_STATUS_URB;
        }

        if (cmdinfo->state & ALLOC_DATA_IN_URB) {
                cmdinfo->data_in_urb = uas_alloc_data_urb(devinfo, gfp,
                                        devinfo->data_in_pipe, cmdinfo->stream,
                                        cmnd, DMA_FROM_DEVICE);
                if (!cmdinfo->data_in_urb)
                        return SCSI_MLQUEUE_DEVICE_BUSY;
                cmdinfo->state &= ~ALLOC_DATA_IN_URB;
        }

        if (cmdinfo->state & SUBMIT_DATA_IN_URB) {
                if (usb_submit_urb(cmdinfo->data_in_urb, gfp)) {
                        scmd_printk(KERN_INFO, cmnd,
                                        "data in urb submission failure\n");
                        return SCSI_MLQUEUE_DEVICE_BUSY;
                }
                cmdinfo->state &= ~SUBMIT_DATA_IN_URB;
                cmdinfo->state |= DATA_IN_URB_INFLIGHT;
        }

        if (cmdinfo->state & ALLOC_DATA_OUT_URB) {
                cmdinfo->data_out_urb = uas_alloc_data_urb(devinfo, gfp,
                                        devinfo->data_out_pipe, cmdinfo->stream,
                                        cmnd, DMA_TO_DEVICE);
                if (!cmdinfo->data_out_urb)
                        return SCSI_MLQUEUE_DEVICE_BUSY;
                cmdinfo->state &= ~ALLOC_DATA_OUT_URB;
        }

        if (cmdinfo->state & SUBMIT_DATA_OUT_URB) {
                if (usb_submit_urb(cmdinfo->data_out_urb, gfp)) {
                        scmd_printk(KERN_INFO, cmnd,
                                        "data out urb submission failure\n");
                        return SCSI_MLQUEUE_DEVICE_BUSY;
                }
                cmdinfo->state &= ~SUBMIT_DATA_OUT_URB;
                cmdinfo->state |= DATA_OUT_URB_INFLIGHT;
        }

        if (cmdinfo->state & ALLOC_CMD_URB) {
                cmdinfo->cmd_urb = uas_alloc_cmd_urb(devinfo, gfp, cmnd,
                                                        cmdinfo->stream);
                if (!cmdinfo->cmd_urb)
                        return SCSI_MLQUEUE_DEVICE_BUSY;
                cmdinfo->state &= ~ALLOC_CMD_URB;
        }

        if (cmdinfo->state & SUBMIT_CMD_URB) {
                if (usb_submit_urb(cmdinfo->cmd_urb, gfp)) {
                        scmd_printk(KERN_INFO, cmnd,
                                        "cmd urb submission failure\n");
                        return SCSI_MLQUEUE_DEVICE_BUSY;
                }
                cmdinfo->state &= ~SUBMIT_CMD_URB;
                cmdinfo->state |= COMMAND_INFLIGHT;
        }

        return 0;
}

static int uas_queuecommand_lck(struct scsi_cmnd *cmnd,
                                        void (*done)(struct scsi_cmnd *))
{
        struct scsi_device *sdev = cmnd->device;
        struct uas_dev_info *devinfo = sdev->hostdata;
        struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
        int err;

        BUILD_BUG_ON(sizeof(struct uas_cmd_info) > sizeof(struct scsi_pointer));

        if (devinfo->cmnd)
                return SCSI_MLQUEUE_DEVICE_BUSY;

        if (blk_rq_tagged(cmnd->request)) {
                cmdinfo->stream = cmnd->request->tag + 2;
        } else {
                devinfo->cmnd = cmnd;
                cmdinfo->stream = 1;
        }

        cmnd->scsi_done = done;

        cmdinfo->state = SUBMIT_STATUS_URB |
                        ALLOC_CMD_URB | SUBMIT_CMD_URB;

        switch (cmnd->sc_data_direction) {
        case DMA_FROM_DEVICE:
                cmdinfo->state |= ALLOC_DATA_IN_URB | SUBMIT_DATA_IN_URB;
                break;
        case DMA_BIDIRECTIONAL:
                cmdinfo->state |= ALLOC_DATA_IN_URB | SUBMIT_DATA_IN_URB;
        case DMA_TO_DEVICE:
                cmdinfo->state |= ALLOC_DATA_OUT_URB | SUBMIT_DATA_OUT_URB;
        case DMA_NONE:
                break;
        }

        if (!devinfo->use_streams) {
                cmdinfo->state &= ~(SUBMIT_DATA_IN_URB | SUBMIT_DATA_OUT_URB);
                cmdinfo->stream = 0;
        }

        err = uas_submit_urbs(cmnd, devinfo, GFP_ATOMIC);
        if (err) {
                /* If we did nothing, give up now */
                if (cmdinfo->state & SUBMIT_STATUS_URB) {
                        return SCSI_MLQUEUE_DEVICE_BUSY;
                }
                spin_lock(&uas_work_lock);
                list_add_tail(&cmdinfo->list, &uas_work_list);
                spin_unlock(&uas_work_lock);
                schedule_work(&uas_work);
        }

        return 0;
}

static DEF_SCSI_QCMD(uas_queuecommand)

static int uas_eh_abort_handler(struct scsi_cmnd *cmnd)
{
        uas_log_cmd_state(cmnd, __func__);

/* XXX: Send ABORT TASK Task Management command */
        return FAILED;
}

static int uas_eh_device_reset_handler(struct scsi_cmnd *cmnd)
{
        struct scsi_device *sdev = cmnd->device;
        sdev_printk(KERN_INFO, sdev, "%s tag %d\n", __func__,
                                                        cmnd->request->tag);

/* XXX: Send LOGICAL UNIT RESET Task Management command */
        return FAILED;
}

static int uas_eh_target_reset_handler(struct scsi_cmnd *cmnd)
{
        struct scsi_device *sdev = cmnd->device;
        sdev_printk(KERN_INFO, sdev, "%s tag %d\n", __func__,
                                                        cmnd->request->tag);

/* XXX: Can we reset just the one USB interface?
 * Would calling usb_set_interface() have the right effect?
 */
        return FAILED;
}

static int uas_eh_bus_reset_handler(struct scsi_cmnd *cmnd)
{
        struct scsi_device *sdev = cmnd->device;
        struct uas_dev_info *devinfo = sdev->hostdata;
        struct usb_device *udev = devinfo->udev;

        sdev_printk(KERN_INFO, sdev, "%s tag %d\n", __func__,
                                                        cmnd->request->tag);

        if (usb_reset_device(udev))
                return SUCCESS;

        return FAILED;
}

static int uas_slave_alloc(struct scsi_device *sdev)
{
        sdev->hostdata = (void *)sdev->host->hostdata[0];
        return 0;
}

static int uas_slave_configure(struct scsi_device *sdev)
{
        struct uas_dev_info *devinfo = sdev->hostdata;
        scsi_set_tag_type(sdev, MSG_ORDERED_TAG);
        scsi_activate_tcq(sdev, devinfo->qdepth - 2);
        return 0;
}

static struct scsi_host_template uas_host_template = {
        .module = THIS_MODULE,
        .name = "uas",
        .queuecommand = uas_queuecommand,
        .slave_alloc = uas_slave_alloc,
        .slave_configure = uas_slave_configure,
        .eh_abort_handler = uas_eh_abort_handler,
        .eh_device_reset_handler = uas_eh_device_reset_handler,
        .eh_target_reset_handler = uas_eh_target_reset_handler,
        .eh_bus_reset_handler = uas_eh_bus_reset_handler,
        .can_queue = 65536,     /* Is there a limit on the _host_ ? */
        .this_id = -1,
        .sg_tablesize = SG_NONE,
        .cmd_per_lun = 1,       /* until we override it */
        .skip_settle_delay = 1,
        .ordered_tag = 1,
};

static struct usb_device_id uas_usb_ids[] = {
        { USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, USB_SC_SCSI, USB_PR_BULK) },
        { USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, USB_SC_SCSI, USB_PR_UAS) },
        /* 0xaa is a prototype device I happen to have access to */
        { USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, USB_SC_SCSI, 0xaa) },
        { }
};
MODULE_DEVICE_TABLE(usb, uas_usb_ids);

static int uas_is_interface(struct usb_host_interface *intf)
{
        return (intf->desc.bInterfaceClass == USB_CLASS_MASS_STORAGE &&
                intf->desc.bInterfaceSubClass == USB_SC_SCSI &&
                intf->desc.bInterfaceProtocol == USB_PR_UAS);
}

static int uas_isnt_supported(struct usb_device *udev)
{
        struct usb_hcd *hcd = bus_to_hcd(udev->bus);

        dev_warn(&udev->dev, "The driver for the USB controller %s does not "
                        "support scatter-gather which is\n",
                        hcd->driver->description);
        dev_warn(&udev->dev, "required by the UAS driver. Please try an"
                        "alternative USB controller if you wish to use UAS.\n");
        return -ENODEV;
}

static int uas_switch_interface(struct usb_device *udev,
                                                struct usb_interface *intf)
{
        int i;
        int sg_supported = udev->bus->sg_tablesize != 0;

        for (i = 0; i < intf->num_altsetting; i++) {
                struct usb_host_interface *alt = &intf->altsetting[i];

                if (uas_is_interface(alt)) {
                        if (!sg_supported)
                                return uas_isnt_supported(udev);
                        return usb_set_interface(udev,
                                                alt->desc.bInterfaceNumber,
                                                alt->desc.bAlternateSetting);
                }
        }

        return -ENODEV;
}

static void uas_configure_endpoints(struct uas_dev_info *devinfo)
{
        struct usb_host_endpoint *eps[4] = { };
        struct usb_interface *intf = devinfo->intf;
        struct usb_device *udev = devinfo->udev;
        struct usb_host_endpoint *endpoint = intf->cur_altsetting->endpoint;
        unsigned i, n_endpoints = intf->cur_altsetting->desc.bNumEndpoints;

        devinfo->uas_sense_old = 0;
        devinfo->cmnd = NULL;

        for (i = 0; i < n_endpoints; i++) {
                unsigned char *extra = endpoint[i].extra;
                int len = endpoint[i].extralen;
                while (len > 1) {
                        if (extra[1] == USB_DT_PIPE_USAGE) {
                                unsigned pipe_id = extra[2];
                                if (pipe_id > 0 && pipe_id < 5)
                                        eps[pipe_id - 1] = &endpoint[i];
                                break;
                        }
                        len -= extra[0];
                        extra += extra[0];
                }
        }

        /*
         * Assume that if we didn't find a control pipe descriptor, we're
         * using a device with old firmware that happens to be set up like
         * this.
         */
        if (!eps[0]) {
                devinfo->cmd_pipe = usb_sndbulkpipe(udev, 1);
                devinfo->status_pipe = usb_rcvbulkpipe(udev, 1);
                devinfo->data_in_pipe = usb_rcvbulkpipe(udev, 2);
                devinfo->data_out_pipe = usb_sndbulkpipe(udev, 2);

                eps[1] = usb_pipe_endpoint(udev, devinfo->status_pipe);
                eps[2] = usb_pipe_endpoint(udev, devinfo->data_in_pipe);
                eps[3] = usb_pipe_endpoint(udev, devinfo->data_out_pipe);
        } else {
                devinfo->cmd_pipe = usb_sndbulkpipe(udev,
                                                eps[0]->desc.bEndpointAddress);
                devinfo->status_pipe = usb_rcvbulkpipe(udev,
                                                eps[1]->desc.bEndpointAddress);
                devinfo->data_in_pipe = usb_rcvbulkpipe(udev,
                                                eps[2]->desc.bEndpointAddress);
                devinfo->data_out_pipe = usb_sndbulkpipe(udev,
                                                eps[3]->desc.bEndpointAddress);
        }

        devinfo->qdepth = usb_alloc_streams(devinfo->intf, eps + 1, 3, 256,
                                                                GFP_KERNEL);
        if (devinfo->qdepth < 0) {
                devinfo->qdepth = 256;
                devinfo->use_streams = 0;
        } else {
                devinfo->use_streams = 1;
        }
}

static void uas_free_streams(struct uas_dev_info *devinfo)
{
        struct usb_device *udev = devinfo->udev;
        struct usb_host_endpoint *eps[3];

        eps[0] = usb_pipe_endpoint(udev, devinfo->status_pipe);
        eps[1] = usb_pipe_endpoint(udev, devinfo->data_in_pipe);
        eps[2] = usb_pipe_endpoint(udev, devinfo->data_out_pipe);
        usb_free_streams(devinfo->intf, eps, 3, GFP_KERNEL);
}

/*
 * XXX: What I'd like to do here is register a SCSI host for each USB host in
 * the system.  Follow usb-storage's design of registering a SCSI host for
 * each USB device for the moment.  Can implement this by walking up the
 * USB hierarchy until we find a USB host.
 */
static int uas_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
        int result;
        struct Scsi_Host *shost;
        struct uas_dev_info *devinfo;
        struct usb_device *udev = interface_to_usbdev(intf);

        if (uas_switch_interface(udev, intf))
                return -ENODEV;

        devinfo = kmalloc(sizeof(struct uas_dev_info), GFP_KERNEL);
        if (!devinfo)
                return -ENOMEM;

        result = -ENOMEM;
        shost = scsi_host_alloc(&uas_host_template, sizeof(void *));
        if (!shost)
                goto free;

        shost->max_cmd_len = 16 + 252;
        shost->max_id = 1;
        shost->sg_tablesize = udev->bus->sg_tablesize;

        devinfo->intf = intf;
        devinfo->udev = udev;
        uas_configure_endpoints(devinfo);

        result = scsi_init_shared_tag_map(shost, devinfo->qdepth - 2);
        if (result)
                goto free;

        result = scsi_add_host(shost, &intf->dev);
        if (result)
                goto deconfig_eps;

        shost->hostdata[0] = (unsigned long)devinfo;

        scsi_scan_host(shost);
        usb_set_intfdata(intf, shost);
        return result;

deconfig_eps:
        uas_free_streams(devinfo);
 free:
        kfree(devinfo);
        if (shost)
                scsi_host_put(shost);
        return result;
}

static int uas_pre_reset(struct usb_interface *intf)
{
/* XXX: Need to return 1 if it's not our device in error handling */
        return 0;
}

static int uas_post_reset(struct usb_interface *intf)
{
/* XXX: Need to return 1 if it's not our device in error handling */
        return 0;
}

static void uas_disconnect(struct usb_interface *intf)
{
        struct Scsi_Host *shost = usb_get_intfdata(intf);
        struct uas_dev_info *devinfo = (void *)shost->hostdata[0];

        scsi_remove_host(shost);
        uas_free_streams(devinfo);
        kfree(devinfo);
}

/*
 * XXX: Should this plug into libusual so we can auto-upgrade devices from
 * Bulk-Only to UAS?
 */
static struct usb_driver uas_driver = {
        .name = "uas",
        .probe = uas_probe,
        .disconnect = uas_disconnect,
        .pre_reset = uas_pre_reset,
        .post_reset = uas_post_reset,
        .id_table = uas_usb_ids,
};

module_usb_driver(uas_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Matthew Wilcox and Sarah Sharp");