// SPDX-License-Identifier: GPL-2.0
/*
 * Greybus "AP" USB driver for "ES2" controller chips
 *
 * Copyright 2014-2015 Google Inc.
 * Copyright 2014-2015 Linaro Ltd.
 */
#include <linux/kthread.h>
#include <linux/sizes.h>
#include <linux/usb.h>
#include <linux/kfifo.h>
#include <linux/debugfs.h>
#include <linux/list.h>
#include <linux/greybus.h>
#include <linux/unaligned.h>

#include "arpc.h"
#include "greybus_trace.h"


/* Default timeout for USB vendor requests. */
#define ES2_USB_CTRL_TIMEOUT    500

/* Default timeout for ARPC CPort requests */
#define ES2_ARPC_CPORT_TIMEOUT  500

/* Fixed CPort numbers */
#define ES2_CPORT_CDSI0         16
#define ES2_CPORT_CDSI1         17

/* Memory sizes for the buffers sent to/from the ES2 controller */
#define ES2_GBUF_MSG_SIZE_MAX   2048

/* Memory sizes for the ARPC buffers */
#define ARPC_OUT_SIZE_MAX       U16_MAX
#define ARPC_IN_SIZE_MAX        128

static const struct usb_device_id id_table[] = {
        { USB_DEVICE(0x18d1, 0x1eaf) },
        { },
};
MODULE_DEVICE_TABLE(usb, id_table);

#define APB1_LOG_SIZE           SZ_16K

/*
 * Number of CPort IN urbs in flight at any point in time.
 * Adjust if we are having stalls in the USB buffer due to not enough urbs in
 * flight.
 */
#define NUM_CPORT_IN_URB        4

/* Number of CPort OUT urbs in flight at any point in time.
 * Adjust if we get messages saying we are out of urbs in the system log.
 */
#define NUM_CPORT_OUT_URB       8

/*
 * Number of ARPC in urbs in flight at any point in time.
 */
#define NUM_ARPC_IN_URB         2

/*
 * @endpoint: bulk in endpoint for CPort data
 * @urb: array of urbs for the CPort in messages
 * @buffer: array of buffers for the @cport_in_urb urbs
 */
struct es2_cport_in {
        __u8 endpoint;
        struct urb *urb[NUM_CPORT_IN_URB];
        u8 *buffer[NUM_CPORT_IN_URB];
};

/**
 * struct es2_ap_dev - ES2 USB Bridge to AP structure
 * @usb_dev: pointer to the USB device we are.
 * @usb_intf: pointer to the USB interface we are bound to.
 * @hd: pointer to our gb_host_device structure
 *
 * @cport_in: endpoint, urbs and buffer for cport in messages
 * @cport_out_endpoint: endpoint for cport out messages
 * @cport_out_urb: array of urbs for the CPort out messages
 * @cport_out_urb_busy: array of flags to see if the @cport_out_urb is busy or
 *                      not.
 * @cport_out_urb_cancelled: array of flags indicating whether the
 *                      corresponding @cport_out_urb is being cancelled
 * @cport_out_urb_lock: locks the @cport_out_urb_busy "list"
 * @cdsi1_in_use: true if cport CDSI1 is in use
 * @apb_log_task: task pointer for logging thread
 * @apb_log_dentry: file system entry for the log file interface
 * @apb_log_enable_dentry: file system entry for enabling logging
 * @apb_log_fifo: kernel FIFO to carry logged data
 * @arpc_urb: array of urbs for the ARPC in messages
 * @arpc_buffer: array of buffers for the @arpc_urb urbs
 * @arpc_endpoint_in: bulk in endpoint for APBridgeA RPC
 * @arpc_id_cycle: gives an unique id to ARPC
 * @arpc_lock: locks ARPC list
 * @arpcs: list of in progress ARPCs
 */
struct es2_ap_dev {
        struct usb_device *usb_dev;
        struct usb_interface *usb_intf;
        struct gb_host_device *hd;

        struct es2_cport_in cport_in;
        __u8 cport_out_endpoint;
        struct urb *cport_out_urb[NUM_CPORT_OUT_URB];
        bool cport_out_urb_busy[NUM_CPORT_OUT_URB];
        bool cport_out_urb_cancelled[NUM_CPORT_OUT_URB];
        spinlock_t cport_out_urb_lock;

        bool cdsi1_in_use;

        struct task_struct *apb_log_task;
        struct dentry *apb_log_dentry;
        struct dentry *apb_log_enable_dentry;
        DECLARE_KFIFO(apb_log_fifo, char, APB1_LOG_SIZE);

        __u8 arpc_endpoint_in;
        struct urb *arpc_urb[NUM_ARPC_IN_URB];
        u8 *arpc_buffer[NUM_ARPC_IN_URB];

        int arpc_id_cycle;
        spinlock_t arpc_lock;
        struct list_head arpcs;
};

struct arpc {
        struct list_head list;
        struct arpc_request_message *req;
        struct arpc_response_message *resp;
        struct completion response_received;
        bool active;
};

static inline struct es2_ap_dev *hd_to_es2(struct gb_host_device *hd)
{
        return (struct es2_ap_dev *)&hd->hd_priv;
}

static void cport_out_callback(struct urb *urb);
static void usb_log_enable(struct es2_ap_dev *es2);
static void usb_log_disable(struct es2_ap_dev *es2);
static int arpc_sync(struct es2_ap_dev *es2, u8 type, void *payload,
                     size_t size, int *result, unsigned int timeout);

static int output_sync(struct es2_ap_dev *es2, void *req, u16 size, u8 cmd)
{
        struct usb_device *udev = es2->usb_dev;
        u8 *data;
        int retval;

        data = kmemdup(req, size, GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        retval = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                 cmd,
                                 USB_DIR_OUT | USB_TYPE_VENDOR |
                                 USB_RECIP_INTERFACE,
                                 0, 0, data, size, ES2_USB_CTRL_TIMEOUT);
        if (retval < 0)
                dev_err(&udev->dev, "%s: return error %d\n", __func__, retval);
        else
                retval = 0;

        kfree(data);
        return retval;
}

static void ap_urb_complete(struct urb *urb)
{
        struct usb_ctrlrequest *dr = urb->context;

        kfree(dr);
        usb_free_urb(urb);
}

static int output_async(struct es2_ap_dev *es2, void *req, u16 size, u8 cmd)
{
        struct usb_device *udev = es2->usb_dev;
        struct urb *urb;
        struct usb_ctrlrequest *dr;
        u8 *buf;
        int retval;

        urb = usb_alloc_urb(0, GFP_ATOMIC);
        if (!urb)
                return -ENOMEM;

        dr = kmalloc(sizeof(*dr) + size, GFP_ATOMIC);
        if (!dr) {
                usb_free_urb(urb);
                return -ENOMEM;
        }

        buf = (u8 *)dr + sizeof(*dr);
        memcpy(buf, req, size);

        dr->bRequest = cmd;
        dr->bRequestType = USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE;
        dr->wValue = 0;
        dr->wIndex = 0;
        dr->wLength = cpu_to_le16(size);

        usb_fill_control_urb(urb, udev, usb_sndctrlpipe(udev, 0),
                             (unsigned char *)dr, buf, size,
                             ap_urb_complete, dr);
        retval = usb_submit_urb(urb, GFP_ATOMIC);
        if (retval) {
                usb_free_urb(urb);
                kfree(dr);
        }
        return retval;
}

static int output(struct gb_host_device *hd, void *req, u16 size, u8 cmd,
                  bool async)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);

        if (async)
                return output_async(es2, req, size, cmd);

        return output_sync(es2, req, size, cmd);
}

static int es2_cport_in_enable(struct es2_ap_dev *es2,
                               struct es2_cport_in *cport_in)
{
        struct urb *urb;
        int ret;
        int i;

        for (i = 0; i < NUM_CPORT_IN_URB; ++i) {
                urb = cport_in->urb[i];

                ret = usb_submit_urb(urb, GFP_KERNEL);
                if (ret) {
                        dev_err(&es2->usb_dev->dev,
                                "failed to submit in-urb: %d\n", ret);
                        goto err_kill_urbs;
                }
        }

        return 0;

err_kill_urbs:
        for (--i; i >= 0; --i) {
                urb = cport_in->urb[i];
                usb_kill_urb(urb);
        }

        return ret;
}

static void es2_cport_in_disable(struct es2_ap_dev *es2,
                                 struct es2_cport_in *cport_in)
{
        struct urb *urb;
        int i;

        for (i = 0; i < NUM_CPORT_IN_URB; ++i) {
                urb = cport_in->urb[i];
                usb_kill_urb(urb);
        }
}

static int es2_arpc_in_enable(struct es2_ap_dev *es2)
{
        struct urb *urb;
        int ret;
        int i;

        for (i = 0; i < NUM_ARPC_IN_URB; ++i) {
                urb = es2->arpc_urb[i];

                ret = usb_submit_urb(urb, GFP_KERNEL);
                if (ret) {
                        dev_err(&es2->usb_dev->dev,
                                "failed to submit arpc in-urb: %d\n", ret);
                        goto err_kill_urbs;
                }
        }

        return 0;

err_kill_urbs:
        for (--i; i >= 0; --i) {
                urb = es2->arpc_urb[i];
                usb_kill_urb(urb);
        }

        return ret;
}

static void es2_arpc_in_disable(struct es2_ap_dev *es2)
{
        struct urb *urb;
        int i;

        for (i = 0; i < NUM_ARPC_IN_URB; ++i) {
                urb = es2->arpc_urb[i];
                usb_kill_urb(urb);
        }
}

static struct urb *next_free_urb(struct es2_ap_dev *es2, gfp_t gfp_mask)
{
        struct urb *urb = NULL;
        unsigned long flags;
        int i;

        spin_lock_irqsave(&es2->cport_out_urb_lock, flags);

        /* Look in our pool of allocated urbs first, as that's the "fastest" */
        for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
                if (!es2->cport_out_urb_busy[i] &&
                    !es2->cport_out_urb_cancelled[i]) {
                        es2->cport_out_urb_busy[i] = true;
                        urb = es2->cport_out_urb[i];
                        break;
                }
        }
        spin_unlock_irqrestore(&es2->cport_out_urb_lock, flags);
        if (urb)
                return urb;

        /*
         * Crap, pool is empty, complain to the syslog and go allocate one
         * dynamically as we have to succeed.
         */
        dev_dbg(&es2->usb_dev->dev,
                "No free CPort OUT urbs, having to dynamically allocate one!\n");
        return usb_alloc_urb(0, gfp_mask);
}

static void free_urb(struct es2_ap_dev *es2, struct urb *urb)
{
        unsigned long flags;
        int i;
        /*
         * See if this was an urb in our pool, if so mark it "free", otherwise
         * we need to free it ourselves.
         */
        spin_lock_irqsave(&es2->cport_out_urb_lock, flags);
        for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
                if (urb == es2->cport_out_urb[i]) {
                        es2->cport_out_urb_busy[i] = false;
                        urb = NULL;
                        break;
                }
        }
        spin_unlock_irqrestore(&es2->cport_out_urb_lock, flags);

        /* If urb is not NULL, then we need to free this urb */
        usb_free_urb(urb);
}

/*
 * We (ab)use the operation-message header pad bytes to transfer the
 * cport id in order to minimise overhead.
 */
static void
gb_message_cport_pack(struct gb_operation_msg_hdr *header, u16 cport_id)
{
        header->pad[0] = cport_id;
}

/* Clear the pad bytes used for the CPort id */
static void gb_message_cport_clear(struct gb_operation_msg_hdr *header)
{
        header->pad[0] = 0;
}

/* Extract the CPort id packed into the header, and clear it */
static u16 gb_message_cport_unpack(struct gb_operation_msg_hdr *header)
{
        u16 cport_id = header->pad[0];

        gb_message_cport_clear(header);

        return cport_id;
}

/*
 * Returns zero if the message was successfully queued, or a negative errno
 * otherwise.
 */
static int message_send(struct gb_host_device *hd, u16 cport_id,
                        struct gb_message *message, gfp_t gfp_mask)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct usb_device *udev = es2->usb_dev;
        size_t buffer_size;
        int retval;
        struct urb *urb;
        unsigned long flags;

        /*
         * The data actually transferred will include an indication
         * of where the data should be sent.  Do one last check of
         * the target CPort id before filling it in.
         */
        if (!cport_id_valid(hd, cport_id)) {
                dev_err(&udev->dev, "invalid cport %u\n", cport_id);
                return -EINVAL;
        }

        /* Find a free urb */
        urb = next_free_urb(es2, gfp_mask);
        if (!urb)
                return -ENOMEM;

        spin_lock_irqsave(&es2->cport_out_urb_lock, flags);
        message->hcpriv = urb;
        spin_unlock_irqrestore(&es2->cport_out_urb_lock, flags);

        /* Pack the cport id into the message header */
        gb_message_cport_pack(message->header, cport_id);

        buffer_size = sizeof(*message->header) + message->payload_size;

        usb_fill_bulk_urb(urb, udev,
                          usb_sndbulkpipe(udev,
                                          es2->cport_out_endpoint),
                          message->buffer, buffer_size,
                          cport_out_callback, message);
        urb->transfer_flags |= URB_ZERO_PACKET;

        trace_gb_message_submit(message);

        retval = usb_submit_urb(urb, gfp_mask);
        if (retval) {
                dev_err(&udev->dev, "failed to submit out-urb: %d\n", retval);

                spin_lock_irqsave(&es2->cport_out_urb_lock, flags);
                message->hcpriv = NULL;
                spin_unlock_irqrestore(&es2->cport_out_urb_lock, flags);

                free_urb(es2, urb);
                gb_message_cport_clear(message->header);

                return retval;
        }

        return 0;
}

/*
 * Can not be called in atomic context.
 */
static void message_cancel(struct gb_message *message)
{
        struct gb_host_device *hd = message->operation->connection->hd;
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct urb *urb;
        int i;

        might_sleep();

        spin_lock_irq(&es2->cport_out_urb_lock);
        urb = message->hcpriv;

        /* Prevent dynamically allocated urb from being deallocated. */
        usb_get_urb(urb);

        /* Prevent pre-allocated urb from being reused. */
        for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
                if (urb == es2->cport_out_urb[i]) {
                        es2->cport_out_urb_cancelled[i] = true;
                        break;
                }
        }
        spin_unlock_irq(&es2->cport_out_urb_lock);

        usb_kill_urb(urb);

        if (i < NUM_CPORT_OUT_URB) {
                spin_lock_irq(&es2->cport_out_urb_lock);
                es2->cport_out_urb_cancelled[i] = false;
                spin_unlock_irq(&es2->cport_out_urb_lock);
        }

        usb_free_urb(urb);
}

static int es2_cport_allocate(struct gb_host_device *hd, int cport_id,
                              unsigned long flags)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct ida *id_map = &hd->cport_id_map;
        int ida_start, ida_end;

        switch (cport_id) {
        case ES2_CPORT_CDSI0:
        case ES2_CPORT_CDSI1:
                dev_err(&hd->dev, "cport %d not available\n", cport_id);
                return -EBUSY;
        }

        if (flags & GB_CONNECTION_FLAG_OFFLOADED &&
            flags & GB_CONNECTION_FLAG_CDSI1) {
                if (es2->cdsi1_in_use) {
                        dev_err(&hd->dev, "CDSI1 already in use\n");
                        return -EBUSY;
                }

                es2->cdsi1_in_use = true;

                return ES2_CPORT_CDSI1;
        }

        if (cport_id < 0) {
                ida_start = 0;
                ida_end = hd->num_cports - 1;
        } else if (cport_id < hd->num_cports) {
                ida_start = cport_id;
                ida_end = cport_id;
        } else {
                dev_err(&hd->dev, "cport %d not available\n", cport_id);
                return -EINVAL;
        }

        return ida_alloc_range(id_map, ida_start, ida_end, GFP_KERNEL);
}

static void es2_cport_release(struct gb_host_device *hd, u16 cport_id)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);

        switch (cport_id) {
        case ES2_CPORT_CDSI1:
                es2->cdsi1_in_use = false;
                return;
        }

        ida_free(&hd->cport_id_map, cport_id);
}

static int cport_enable(struct gb_host_device *hd, u16 cport_id,
                        unsigned long flags)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct usb_device *udev = es2->usb_dev;
        struct gb_apb_request_cport_flags *req;
        u32 connection_flags;
        int ret;

        req = kzalloc_obj(*req);
        if (!req)
                return -ENOMEM;

        connection_flags = 0;
        if (flags & GB_CONNECTION_FLAG_CONTROL)
                connection_flags |= GB_APB_CPORT_FLAG_CONTROL;
        if (flags & GB_CONNECTION_FLAG_HIGH_PRIO)
                connection_flags |= GB_APB_CPORT_FLAG_HIGH_PRIO;

        req->flags = cpu_to_le32(connection_flags);

        dev_dbg(&hd->dev, "%s - cport = %u, flags = %02x\n", __func__,
                cport_id, connection_flags);

        ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                              GB_APB_REQUEST_CPORT_FLAGS,
                              USB_DIR_OUT | USB_TYPE_VENDOR |
                              USB_RECIP_INTERFACE, cport_id, 0,
                              req, sizeof(*req), ES2_USB_CTRL_TIMEOUT);
        if (ret < 0) {
                dev_err(&udev->dev, "failed to set cport flags for port %d\n",
                        cport_id);
                goto out;
        }

        ret = 0;
out:
        kfree(req);

        return ret;
}

static int es2_cport_connected(struct gb_host_device *hd, u16 cport_id)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct device *dev = &es2->usb_dev->dev;
        struct arpc_cport_connected_req req;
        int ret;

        req.cport_id = cpu_to_le16(cport_id);
        ret = arpc_sync(es2, ARPC_TYPE_CPORT_CONNECTED, &req, sizeof(req),
                        NULL, ES2_ARPC_CPORT_TIMEOUT);
        if (ret) {
                dev_err(dev, "failed to set connected state for cport %u: %d\n",
                        cport_id, ret);
                return ret;
        }

        return 0;
}

static int es2_cport_flush(struct gb_host_device *hd, u16 cport_id)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct device *dev = &es2->usb_dev->dev;
        struct arpc_cport_flush_req req;
        int ret;

        req.cport_id = cpu_to_le16(cport_id);
        ret = arpc_sync(es2, ARPC_TYPE_CPORT_FLUSH, &req, sizeof(req),
                        NULL, ES2_ARPC_CPORT_TIMEOUT);
        if (ret) {
                dev_err(dev, "failed to flush cport %u: %d\n", cport_id, ret);
                return ret;
        }

        return 0;
}

static int es2_cport_shutdown(struct gb_host_device *hd, u16 cport_id,
                              u8 phase, unsigned int timeout)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct device *dev = &es2->usb_dev->dev;
        struct arpc_cport_shutdown_req req;
        int result;
        int ret;

        if (timeout > U16_MAX)
                return -EINVAL;

        req.cport_id = cpu_to_le16(cport_id);
        req.timeout = cpu_to_le16(timeout);
        req.phase = phase;
        ret = arpc_sync(es2, ARPC_TYPE_CPORT_SHUTDOWN, &req, sizeof(req),
                        &result, ES2_ARPC_CPORT_TIMEOUT + timeout);
        if (ret) {
                dev_err(dev, "failed to send shutdown over cport %u: %d (%d)\n",
                        cport_id, ret, result);
                return ret;
        }

        return 0;
}

static int es2_cport_quiesce(struct gb_host_device *hd, u16 cport_id,
                             size_t peer_space, unsigned int timeout)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct device *dev = &es2->usb_dev->dev;
        struct arpc_cport_quiesce_req req;
        int result;
        int ret;

        if (peer_space > U16_MAX)
                return -EINVAL;

        if (timeout > U16_MAX)
                return -EINVAL;

        req.cport_id = cpu_to_le16(cport_id);
        req.peer_space = cpu_to_le16(peer_space);
        req.timeout = cpu_to_le16(timeout);
        ret = arpc_sync(es2, ARPC_TYPE_CPORT_QUIESCE, &req, sizeof(req),
                        &result, ES2_ARPC_CPORT_TIMEOUT + timeout);
        if (ret) {
                dev_err(dev, "failed to quiesce cport %u: %d (%d)\n",
                        cport_id, ret, result);
                return ret;
        }

        return 0;
}

static int es2_cport_clear(struct gb_host_device *hd, u16 cport_id)
{
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct device *dev = &es2->usb_dev->dev;
        struct arpc_cport_clear_req req;
        int ret;

        req.cport_id = cpu_to_le16(cport_id);
        ret = arpc_sync(es2, ARPC_TYPE_CPORT_CLEAR, &req, sizeof(req),
                        NULL, ES2_ARPC_CPORT_TIMEOUT);
        if (ret) {
                dev_err(dev, "failed to clear cport %u: %d\n", cport_id, ret);
                return ret;
        }

        return 0;
}

static int latency_tag_enable(struct gb_host_device *hd, u16 cport_id)
{
        int retval;
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct usb_device *udev = es2->usb_dev;

        retval = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                 GB_APB_REQUEST_LATENCY_TAG_EN,
                                 USB_DIR_OUT | USB_TYPE_VENDOR |
                                 USB_RECIP_INTERFACE, cport_id, 0, NULL,
                                 0, ES2_USB_CTRL_TIMEOUT);

        if (retval < 0)
                dev_err(&udev->dev, "Cannot enable latency tag for cport %d\n",
                        cport_id);
        return retval;
}

static int latency_tag_disable(struct gb_host_device *hd, u16 cport_id)
{
        int retval;
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        struct usb_device *udev = es2->usb_dev;

        retval = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                 GB_APB_REQUEST_LATENCY_TAG_DIS,
                                 USB_DIR_OUT | USB_TYPE_VENDOR |
                                 USB_RECIP_INTERFACE, cport_id, 0, NULL,
                                 0, ES2_USB_CTRL_TIMEOUT);

        if (retval < 0)
                dev_err(&udev->dev, "Cannot disable latency tag for cport %d\n",
                        cport_id);
        return retval;
}

static struct gb_hd_driver es2_driver = {
        .hd_priv_size                   = sizeof(struct es2_ap_dev),
        .message_send                   = message_send,
        .message_cancel                 = message_cancel,
        .cport_allocate                 = es2_cport_allocate,
        .cport_release                  = es2_cport_release,
        .cport_enable                   = cport_enable,
        .cport_connected                = es2_cport_connected,
        .cport_flush                    = es2_cport_flush,
        .cport_shutdown                 = es2_cport_shutdown,
        .cport_quiesce                  = es2_cport_quiesce,
        .cport_clear                    = es2_cport_clear,
        .latency_tag_enable             = latency_tag_enable,
        .latency_tag_disable            = latency_tag_disable,
        .output                         = output,
};

/* Common function to report consistent warnings based on URB status */
static int check_urb_status(struct urb *urb)
{
        struct device *dev = &urb->dev->dev;
        int status = urb->status;

        switch (status) {
        case 0:
                return 0;

        case -EOVERFLOW:
                dev_err(dev, "%s: overflow actual length is %d\n",
                        __func__, urb->actual_length);
                fallthrough;
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
        case -EILSEQ:
        case -EPROTO:
                /* device is gone, stop sending */
                return status;
        }
        dev_err(dev, "%s: unknown status %d\n", __func__, status);

        return -EAGAIN;
}

static void es2_destroy(struct es2_ap_dev *es2)
{
        struct usb_device *udev;
        struct urb *urb;
        int i;

        debugfs_remove(es2->apb_log_enable_dentry);
        usb_log_disable(es2);

        /* Tear down everything! */
        for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
                urb = es2->cport_out_urb[i];
                usb_kill_urb(urb);
                usb_free_urb(urb);
                es2->cport_out_urb[i] = NULL;
                es2->cport_out_urb_busy[i] = false;     /* just to be anal */
        }

        for (i = 0; i < NUM_ARPC_IN_URB; ++i) {
                usb_free_urb(es2->arpc_urb[i]);
                kfree(es2->arpc_buffer[i]);
                es2->arpc_buffer[i] = NULL;
        }

        for (i = 0; i < NUM_CPORT_IN_URB; ++i) {
                usb_free_urb(es2->cport_in.urb[i]);
                kfree(es2->cport_in.buffer[i]);
                es2->cport_in.buffer[i] = NULL;
        }

        /* release reserved CDSI0 and CDSI1 cports */
        gb_hd_cport_release_reserved(es2->hd, ES2_CPORT_CDSI1);
        gb_hd_cport_release_reserved(es2->hd, ES2_CPORT_CDSI0);

        udev = es2->usb_dev;
        gb_hd_put(es2->hd);

        usb_put_dev(udev);
}

static void cport_in_callback(struct urb *urb)
{
        struct gb_host_device *hd = urb->context;
        struct device *dev = &urb->dev->dev;
        struct gb_operation_msg_hdr *header;
        int status = check_urb_status(urb);
        int retval;
        u16 cport_id;

        if (status) {
                if ((status == -EAGAIN) || (status == -EPROTO))
                        goto exit;

                /* The urb is being unlinked */
                if (status == -ENOENT || status == -ESHUTDOWN)
                        return;

                dev_err(dev, "urb cport in error %d (dropped)\n", status);
                return;
        }

        if (urb->actual_length < sizeof(*header)) {
                dev_err(dev, "short message received\n");
                goto exit;
        }

        /* Extract the CPort id, which is packed in the message header */
        header = urb->transfer_buffer;
        cport_id = gb_message_cport_unpack(header);

        if (cport_id_valid(hd, cport_id)) {
                greybus_data_rcvd(hd, cport_id, urb->transfer_buffer,
                                  urb->actual_length);
        } else {
                dev_err(dev, "invalid cport id %u received\n", cport_id);
        }
exit:
        /* put our urb back in the request pool */
        retval = usb_submit_urb(urb, GFP_ATOMIC);
        if (retval)
                dev_err(dev, "failed to resubmit in-urb: %d\n", retval);
}

static void cport_out_callback(struct urb *urb)
{
        struct gb_message *message = urb->context;
        struct gb_host_device *hd = message->operation->connection->hd;
        struct es2_ap_dev *es2 = hd_to_es2(hd);
        int status = check_urb_status(urb);
        unsigned long flags;

        gb_message_cport_clear(message->header);

        spin_lock_irqsave(&es2->cport_out_urb_lock, flags);
        message->hcpriv = NULL;
        spin_unlock_irqrestore(&es2->cport_out_urb_lock, flags);

        /*
         * Tell the submitter that the message send (attempt) is
         * complete, and report the status.
         */
        greybus_message_sent(hd, message, status);

        free_urb(es2, urb);
}

static struct arpc *arpc_alloc(void *payload, u16 size, u8 type)
{
        struct arpc *rpc;

        if (size + sizeof(*rpc->req) > ARPC_OUT_SIZE_MAX)
                return NULL;

        rpc = kzalloc_obj(*rpc);
        if (!rpc)
                return NULL;

        INIT_LIST_HEAD(&rpc->list);
        rpc->req = kzalloc(sizeof(*rpc->req) + size, GFP_KERNEL);
        if (!rpc->req)
                goto err_free_rpc;

        rpc->resp = kzalloc_obj(*rpc->resp);
        if (!rpc->resp)
                goto err_free_req;

        rpc->req->type = type;
        rpc->req->size = cpu_to_le16(sizeof(*rpc->req) + size);
        memcpy(rpc->req->data, payload, size);

        init_completion(&rpc->response_received);

        return rpc;

err_free_req:
        kfree(rpc->req);
err_free_rpc:
        kfree(rpc);

        return NULL;
}

static void arpc_free(struct arpc *rpc)
{
        kfree(rpc->req);
        kfree(rpc->resp);
        kfree(rpc);
}

static struct arpc *arpc_find(struct es2_ap_dev *es2, __le16 id)
{
        struct arpc *rpc;

        list_for_each_entry(rpc, &es2->arpcs, list) {
                if (rpc->req->id == id)
                        return rpc;
        }

        return NULL;
}

static void arpc_add(struct es2_ap_dev *es2, struct arpc *rpc)
{
        rpc->active = true;
        rpc->req->id = cpu_to_le16(es2->arpc_id_cycle++);
        list_add_tail(&rpc->list, &es2->arpcs);
}

static void arpc_del(struct es2_ap_dev *es2, struct arpc *rpc)
{
        if (rpc->active) {
                rpc->active = false;
                list_del(&rpc->list);
        }
}

static int arpc_send(struct es2_ap_dev *es2, struct arpc *rpc, int timeout)
{
        struct usb_device *udev = es2->usb_dev;
        int retval;

        retval = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                 GB_APB_REQUEST_ARPC_RUN,
                                 USB_DIR_OUT | USB_TYPE_VENDOR |
                                 USB_RECIP_INTERFACE,
                                 0, 0,
                                 rpc->req, le16_to_cpu(rpc->req->size),
                                 ES2_USB_CTRL_TIMEOUT);
        if (retval < 0) {
                dev_err(&udev->dev,
                        "failed to send ARPC request %d: %d\n",
                        rpc->req->type, retval);
                return retval;
        }

        return 0;
}

static int arpc_sync(struct es2_ap_dev *es2, u8 type, void *payload,
                     size_t size, int *result, unsigned int timeout)
{
        struct arpc *rpc;
        unsigned long flags;
        int retval;

        if (result)
                *result = 0;

        rpc = arpc_alloc(payload, size, type);
        if (!rpc)
                return -ENOMEM;

        spin_lock_irqsave(&es2->arpc_lock, flags);
        arpc_add(es2, rpc);
        spin_unlock_irqrestore(&es2->arpc_lock, flags);

        retval = arpc_send(es2, rpc, timeout);
        if (retval)
                goto out_arpc_del;

        retval = wait_for_completion_interruptible_timeout(
                                                &rpc->response_received,
                                                msecs_to_jiffies(timeout));
        if (retval <= 0) {
                if (!retval)
                        retval = -ETIMEDOUT;
                goto out_arpc_del;
        }

        if (rpc->resp->result) {
                retval = -EREMOTEIO;
                if (result)
                        *result = rpc->resp->result;
        } else {
                retval = 0;
        }

out_arpc_del:
        spin_lock_irqsave(&es2->arpc_lock, flags);
        arpc_del(es2, rpc);
        spin_unlock_irqrestore(&es2->arpc_lock, flags);
        arpc_free(rpc);

        if (retval < 0 && retval != -EREMOTEIO) {
                dev_err(&es2->usb_dev->dev,
                        "failed to execute ARPC: %d\n", retval);
        }

        return retval;
}

static void arpc_in_callback(struct urb *urb)
{
        struct es2_ap_dev *es2 = urb->context;
        struct device *dev = &urb->dev->dev;
        int status = check_urb_status(urb);
        struct arpc *rpc;
        struct arpc_response_message *resp;
        unsigned long flags;
        int retval;

        if (status) {
                if ((status == -EAGAIN) || (status == -EPROTO))
                        goto exit;

                /* The urb is being unlinked */
                if (status == -ENOENT || status == -ESHUTDOWN)
                        return;

                dev_err(dev, "arpc in-urb error %d (dropped)\n", status);
                return;
        }

        if (urb->actual_length < sizeof(*resp)) {
                dev_err(dev, "short aprc response received\n");
                goto exit;
        }

        resp = urb->transfer_buffer;
        spin_lock_irqsave(&es2->arpc_lock, flags);
        rpc = arpc_find(es2, resp->id);
        if (!rpc) {
                dev_err(dev, "invalid arpc response id received: %u\n",
                        le16_to_cpu(resp->id));
                spin_unlock_irqrestore(&es2->arpc_lock, flags);
                goto exit;
        }

        arpc_del(es2, rpc);
        memcpy(rpc->resp, resp, sizeof(*resp));
        complete(&rpc->response_received);
        spin_unlock_irqrestore(&es2->arpc_lock, flags);

exit:
        /* put our urb back in the request pool */
        retval = usb_submit_urb(urb, GFP_ATOMIC);
        if (retval)
                dev_err(dev, "failed to resubmit arpc in-urb: %d\n", retval);
}

#define APB1_LOG_MSG_SIZE       64
static void apb_log_get(struct es2_ap_dev *es2, char *buf)
{
        int retval;

        do {
                retval = usb_control_msg(es2->usb_dev,
                                         usb_rcvctrlpipe(es2->usb_dev, 0),
                                         GB_APB_REQUEST_LOG,
                                         USB_DIR_IN | USB_TYPE_VENDOR |
                                         USB_RECIP_INTERFACE,
                                         0x00, 0x00,
                                         buf,
                                         APB1_LOG_MSG_SIZE,
                                         ES2_USB_CTRL_TIMEOUT);
                if (retval > 0)
                        kfifo_in(&es2->apb_log_fifo, buf, retval);
        } while (retval > 0);
}

static int apb_log_poll(void *data)
{
        struct es2_ap_dev *es2 = data;
        char *buf;

        buf = kmalloc(APB1_LOG_MSG_SIZE, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        while (!kthread_should_stop()) {
                msleep(1000);
                apb_log_get(es2, buf);
        }

        kfree(buf);

        return 0;
}

static ssize_t apb_log_read(struct file *f, char __user *buf,
                            size_t count, loff_t *ppos)
{
        struct es2_ap_dev *es2 = file_inode(f)->i_private;
        ssize_t ret;
        size_t copied;
        char *tmp_buf;

        if (count > APB1_LOG_SIZE)
                count = APB1_LOG_SIZE;

        tmp_buf = kmalloc(count, GFP_KERNEL);
        if (!tmp_buf)
                return -ENOMEM;

        copied = kfifo_out(&es2->apb_log_fifo, tmp_buf, count);
        ret = simple_read_from_buffer(buf, count, ppos, tmp_buf, copied);

        kfree(tmp_buf);

        return ret;
}

static const struct file_operations apb_log_fops = {
        .read   = apb_log_read,
};

static void usb_log_enable(struct es2_ap_dev *es2)
{
        if (!IS_ERR_OR_NULL(es2->apb_log_task))
                return;

        /* get log from APB1 */
        es2->apb_log_task = kthread_run(apb_log_poll, es2, "apb_log");
        if (IS_ERR(es2->apb_log_task))
                return;
        /* XXX We will need to rename this per APB */
        es2->apb_log_dentry = debugfs_create_file("apb_log", 0444,
                                                  gb_debugfs_get(), es2,
                                                  &apb_log_fops);
}

static void usb_log_disable(struct es2_ap_dev *es2)
{
        if (IS_ERR_OR_NULL(es2->apb_log_task))
                return;

        debugfs_remove(es2->apb_log_dentry);
        es2->apb_log_dentry = NULL;

        kthread_stop(es2->apb_log_task);
        es2->apb_log_task = NULL;
}

static ssize_t apb_log_enable_read(struct file *f, char __user *buf,
                                   size_t count, loff_t *ppos)
{
        struct es2_ap_dev *es2 = file_inode(f)->i_private;
        int enable = !IS_ERR_OR_NULL(es2->apb_log_task);
        char tmp_buf[3];

        sprintf(tmp_buf, "%d\n", enable);
        return simple_read_from_buffer(buf, count, ppos, tmp_buf, 2);
}

static ssize_t apb_log_enable_write(struct file *f, const char __user *buf,
                                    size_t count, loff_t *ppos)
{
        int enable;
        ssize_t retval;
        struct es2_ap_dev *es2 = file_inode(f)->i_private;

        retval = kstrtoint_from_user(buf, count, 10, &enable);
        if (retval)
                return retval;

        if (enable)
                usb_log_enable(es2);
        else
                usb_log_disable(es2);

        return count;
}

static const struct file_operations apb_log_enable_fops = {
        .read   = apb_log_enable_read,
        .write  = apb_log_enable_write,
};

static int apb_get_cport_count(struct usb_device *udev)
{
        int retval;
        __le16 *cport_count;

        cport_count = kzalloc_obj(*cport_count);
        if (!cport_count)
                return -ENOMEM;

        retval = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
                                 GB_APB_REQUEST_CPORT_COUNT,
                                 USB_DIR_IN | USB_TYPE_VENDOR |
                                 USB_RECIP_INTERFACE, 0, 0, cport_count,
                                 sizeof(*cport_count), ES2_USB_CTRL_TIMEOUT);
        if (retval != sizeof(*cport_count)) {
                dev_err(&udev->dev, "Cannot retrieve CPort count: %d\n",
                        retval);

                if (retval >= 0)
                        retval = -EIO;

                goto out;
        }

        retval = le16_to_cpu(*cport_count);

        /* We need to fit a CPort ID in one byte of a message header */
        if (retval > U8_MAX) {
                retval = U8_MAX;
                dev_warn(&udev->dev, "Limiting number of CPorts to U8_MAX\n");
        }

out:
        kfree(cport_count);
        return retval;
}

/*
 * The ES2 USB Bridge device has 15 endpoints
 * 1 Control - usual USB stuff + AP -> APBridgeA messages
 * 7 Bulk IN - CPort data in
 * 7 Bulk OUT - CPort data out
 */
static int ap_probe(struct usb_interface *interface,
                    const struct usb_device_id *id)
{
        struct es2_ap_dev *es2;
        struct gb_host_device *hd;
        struct usb_device *udev;
        struct usb_host_interface *iface_desc;
        struct usb_endpoint_descriptor *endpoint;
        __u8 ep_addr;
        int retval;
        int i;
        int num_cports;
        bool bulk_out_found = false;
        bool bulk_in_found = false;
        bool arpc_in_found = false;

        udev = usb_get_dev(interface_to_usbdev(interface));

        num_cports = apb_get_cport_count(udev);
        if (num_cports < 0) {
                usb_put_dev(udev);
                dev_err(&udev->dev, "Cannot retrieve CPort count: %d\n",
                        num_cports);
                return num_cports;
        }

        hd = gb_hd_create(&es2_driver, &udev->dev, ES2_GBUF_MSG_SIZE_MAX,
                          num_cports);
        if (IS_ERR(hd)) {
                usb_put_dev(udev);
                return PTR_ERR(hd);
        }

        es2 = hd_to_es2(hd);
        es2->hd = hd;
        es2->usb_intf = interface;
        es2->usb_dev = udev;
        spin_lock_init(&es2->cport_out_urb_lock);
        INIT_KFIFO(es2->apb_log_fifo);
        usb_set_intfdata(interface, es2);

        /*
         * Reserve the CDSI0 and CDSI1 CPorts so they won't be allocated
         * dynamically.
         */
        retval = gb_hd_cport_reserve(hd, ES2_CPORT_CDSI0);
        if (retval)
                goto error;
        retval = gb_hd_cport_reserve(hd, ES2_CPORT_CDSI1);
        if (retval)
                goto error;

        /* find all bulk endpoints */
        iface_desc = interface->cur_altsetting;
        for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
                endpoint = &iface_desc->endpoint[i].desc;
                ep_addr = endpoint->bEndpointAddress;

                if (usb_endpoint_is_bulk_in(endpoint)) {
                        if (!bulk_in_found) {
                                es2->cport_in.endpoint = ep_addr;
                                bulk_in_found = true;
                        } else if (!arpc_in_found) {
                                es2->arpc_endpoint_in = ep_addr;
                                arpc_in_found = true;
                        } else {
                                dev_warn(&udev->dev,
                                         "Unused bulk IN endpoint found: 0x%02x\n",
                                         ep_addr);
                        }
                        continue;
                }
                if (usb_endpoint_is_bulk_out(endpoint)) {
                        if (!bulk_out_found) {
                                es2->cport_out_endpoint = ep_addr;
                                bulk_out_found = true;
                        } else {
                                dev_warn(&udev->dev,
                                         "Unused bulk OUT endpoint found: 0x%02x\n",
                                         ep_addr);
                        }
                        continue;
                }
                dev_warn(&udev->dev,
                         "Unknown endpoint type found, address 0x%02x\n",
                         ep_addr);
        }
        if (!bulk_in_found || !arpc_in_found || !bulk_out_found) {
                dev_err(&udev->dev, "Not enough endpoints found in device, aborting!\n");
                retval = -ENODEV;
                goto error;
        }

        /* Allocate buffers for our cport in messages */
        for (i = 0; i < NUM_CPORT_IN_URB; ++i) {
                struct urb *urb;
                u8 *buffer;

                urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!urb) {
                        retval = -ENOMEM;
                        goto error;
                }
                es2->cport_in.urb[i] = urb;

                buffer = kmalloc(ES2_GBUF_MSG_SIZE_MAX, GFP_KERNEL);
                if (!buffer) {
                        retval = -ENOMEM;
                        goto error;
                }

                usb_fill_bulk_urb(urb, udev,
                                  usb_rcvbulkpipe(udev, es2->cport_in.endpoint),
                                  buffer, ES2_GBUF_MSG_SIZE_MAX,
                                  cport_in_callback, hd);

                es2->cport_in.buffer[i] = buffer;
        }

        /* Allocate buffers for ARPC in messages */
        for (i = 0; i < NUM_ARPC_IN_URB; ++i) {
                struct urb *urb;
                u8 *buffer;

                urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!urb) {
                        retval = -ENOMEM;
                        goto error;
                }
                es2->arpc_urb[i] = urb;

                buffer = kmalloc(ARPC_IN_SIZE_MAX, GFP_KERNEL);
                if (!buffer) {
                        retval = -ENOMEM;
                        goto error;
                }

                usb_fill_bulk_urb(urb, udev,
                                  usb_rcvbulkpipe(udev,
                                                  es2->arpc_endpoint_in),
                                  buffer, ARPC_IN_SIZE_MAX,
                                  arpc_in_callback, es2);

                es2->arpc_buffer[i] = buffer;
        }

        /* Allocate urbs for our CPort OUT messages */
        for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {
                struct urb *urb;

                urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!urb) {
                        retval = -ENOMEM;
                        goto error;
                }

                es2->cport_out_urb[i] = urb;
                es2->cport_out_urb_busy[i] = false;     /* just to be anal */
        }

        /* XXX We will need to rename this per APB */
        es2->apb_log_enable_dentry = debugfs_create_file("apb_log_enable",
                                                         0644,
                                                         gb_debugfs_get(), es2,
                                                         &apb_log_enable_fops);

        INIT_LIST_HEAD(&es2->arpcs);
        spin_lock_init(&es2->arpc_lock);

        retval = es2_arpc_in_enable(es2);
        if (retval)
                goto error;

        retval = gb_hd_add(hd);
        if (retval)
                goto err_disable_arpc_in;

        retval = es2_cport_in_enable(es2, &es2->cport_in);
        if (retval)
                goto err_hd_del;

        return 0;

err_hd_del:
        gb_hd_del(hd);
err_disable_arpc_in:
        es2_arpc_in_disable(es2);
error:
        es2_destroy(es2);

        return retval;
}

static void ap_disconnect(struct usb_interface *interface)
{
        struct es2_ap_dev *es2 = usb_get_intfdata(interface);

        gb_hd_del(es2->hd);

        es2_cport_in_disable(es2, &es2->cport_in);
        es2_arpc_in_disable(es2);

        es2_destroy(es2);
}

static struct usb_driver es2_ap_driver = {
        .name =         "es2_ap_driver",
        .probe =        ap_probe,
        .disconnect =   ap_disconnect,
        .id_table =     id_table,
        .soft_unbind =  1,
};

module_usb_driver(es2_ap_driver);

MODULE_DESCRIPTION("Greybus AP USB driver for ES2 controller chips");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Greg Kroah-Hartman <gregkh@linuxfoundation.org>");