chnl_sm.c

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/*
 * chnl_sm.c
 *
 * DSP-BIOS Bridge driver support functions for TI OMAP processors.
 *
 * Implements upper edge functions for Bridge driver channel module.
 *
 * Copyright (C) 2005-2006 Texas Instruments, Inc.
 *
 * This package is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/*
 *      The lower edge functions must be implemented by the Bridge driver
 *      writer, and are declared in chnl_sm.h.
 *
 *      Care is taken in this code to prevent simultaneous access to channel
 *      queues from
 *      1. Threads.
 *      2. io_dpc(), scheduled from the io_isr() as an event.
 *
 *      This is done primarily by:
 *      - Semaphores.
 *      - state flags in the channel object; and
 *      - ensuring the IO_Dispatch() routine, which is called from both
 *        CHNL_AddIOReq() and the DPC(if implemented), is not re-entered.
 *
 *  Channel Invariant:
 *      There is an important invariant condition which must be maintained per
 *      channel outside of bridge_chnl_get_ioc() and IO_Dispatch(), violation of
 *      which may cause timeouts and/or failure of function sync_wait_on_event.
 *      This invariant condition is:
 *
 *          list_empty(&pchnl->io_completions) ==> pchnl->sync_event is reset
 *      and
 *          !list_empty(&pchnl->io_completions) ==> pchnl->sync_event is set.
 */

#include <linux/types.h>

/*  ----------------------------------- OS */
#include <dspbridge/host_os.h>

/*  ----------------------------------- DSP/BIOS Bridge */
#include <dspbridge/dbdefs.h>

/*  ----------------------------------- OS Adaptation Layer */
#include <dspbridge/sync.h>

/*  ----------------------------------- Bridge Driver */
#include <dspbridge/dspdefs.h>
#include <dspbridge/dspchnl.h>
#include "_tiomap.h"

/*  ----------------------------------- Platform Manager */
#include <dspbridge/dev.h>

/*  ----------------------------------- Others */
#include <dspbridge/io_sm.h>

/*  ----------------------------------- Define for This */
#define USERMODE_ADDR   PAGE_OFFSET

#define MAILBOX_IRQ INT_MAIL_MPU_IRQ

/*  ----------------------------------- Function Prototypes */
static int create_chirp_list(struct list_head *list, u32 chirps);

static void free_chirp_list(struct list_head *list);

static int search_free_channel(struct chnl_mgr *chnl_mgr_obj,
                      u32 *chnl);

/*
 *  ======== bridge_chnl_add_io_req ========
 *      Enqueue an I/O request for data transfer on a channel to the DSP.
 *      The direction (mode) is specified in the channel object. Note the DSP
 *      address is specified for channels opened in direct I/O mode.
 */
int bridge_chnl_add_io_req(struct chnl_object *chnl_obj, void *host_buf,
                   u32 byte_size, u32 buf_size,
                   u32 dw_dsp_addr, u32 dw_arg)
{
    int status = 0;
    struct chnl_object *pchnl = (struct chnl_object *)chnl_obj;
    struct chnl_irp *chnl_packet_obj = NULL;
    struct bridge_dev_context *dev_ctxt;
    struct dev_object *dev_obj;
    u8 dw_state;
    bool is_eos;
    struct chnl_mgr *chnl_mgr_obj;
    u8 *host_sys_buf = NULL;
    bool sched_dpc = false;
    u16 mb_val = 0;

    is_eos = (byte_size == 0);

    /* Validate args */
    if (!host_buf || !pchnl)
        return -EFAULT;

    if (is_eos && CHNL_IS_INPUT(pchnl->chnl_mode))
        return -EPERM;

    /*
     * Check the channel state: only queue chirp if channel state
     * allows it.
     */
    dw_state = pchnl->state;
    if (dw_state != CHNL_STATEREADY) {
        if (dw_state & CHNL_STATECANCEL)
            return -ECANCELED;
        if ((dw_state & CHNL_STATEEOS) &&
                CHNL_IS_OUTPUT(pchnl->chnl_mode))
            return -EPIPE;
        /* No other possible states left */
    }

    dev_obj = dev_get_first();
    dev_get_bridge_context(dev_obj, &dev_ctxt);
    if (!dev_ctxt)
        return -EFAULT;

    if (pchnl->chnl_type == CHNL_PCPY && pchnl->chnl_id > 1 && host_buf) {
        if (!(host_buf < (void *)USERMODE_ADDR)) {
            host_sys_buf = host_buf;
            goto func_cont;
        }
        /* if addr in user mode, then copy to kernel space */
        host_sys_buf = kmalloc(buf_size, GFP_KERNEL);
        if (host_sys_buf == NULL)
            return -ENOMEM;

        if (CHNL_IS_OUTPUT(pchnl->chnl_mode)) {
            status = copy_from_user(host_sys_buf, host_buf,
                    buf_size);
            if (status) {
                kfree(host_sys_buf);
                host_sys_buf = NULL;
                return -EFAULT;
            }
        }
    }
func_cont:
    /* Mailbox IRQ is disabled to avoid race condition with DMA/ZCPY
     * channels. DPCCS is held to avoid race conditions with PCPY channels.
     * If DPC is scheduled in process context (iosm_schedule) and any
     * non-mailbox interrupt occurs, that DPC will run and break CS. Hence
     * we disable ALL DPCs. We will try to disable ONLY IO DPC later. */
    chnl_mgr_obj = pchnl->chnl_mgr_obj;
    spin_lock_bh(&chnl_mgr_obj->chnl_mgr_lock);
    omap_mbox_disable_irq(dev_ctxt->mbox, IRQ_RX);
    if (pchnl->chnl_type == CHNL_PCPY) {
        /* This is a processor-copy channel. */
        if (CHNL_IS_OUTPUT(pchnl->chnl_mode)) {
            /* Check buffer size on output channels for fit. */
            if (byte_size > io_buf_size(
                        pchnl->chnl_mgr_obj->iomgr)) {
                status = -EINVAL;
                goto out;
            }
        }
    }

    /* Get a free chirp: */
    if (list_empty(&pchnl->free_packets_list)) {
        status = -EIO;
        goto out;
    }
    chnl_packet_obj = list_first_entry(&pchnl->free_packets_list,
            struct chnl_irp, link);
    list_del(&chnl_packet_obj->link);

    /* Enqueue the chirp on the chnl's IORequest queue: */
    chnl_packet_obj->host_user_buf = chnl_packet_obj->host_sys_buf =
        host_buf;
    if (pchnl->chnl_type == CHNL_PCPY && pchnl->chnl_id > 1)
        chnl_packet_obj->host_sys_buf = host_sys_buf;

    /*
     * Note: for dma chans dw_dsp_addr contains dsp address
     * of SM buffer.
     */
    /* DSP address */
    chnl_packet_obj->dsp_tx_addr = dw_dsp_addr / chnl_mgr_obj->word_size;
    chnl_packet_obj->byte_size = byte_size;
    chnl_packet_obj->buf_size = buf_size;
    /* Only valid for output channel */
    chnl_packet_obj->arg = dw_arg;
    chnl_packet_obj->status = (is_eos ? CHNL_IOCSTATEOS :
            CHNL_IOCSTATCOMPLETE);
    list_add_tail(&chnl_packet_obj->link, &pchnl->io_requests);
    pchnl->cio_reqs++;
    /*
     * If end of stream, update the channel state to prevent
     * more IOR's.
     */
    if (is_eos)
        pchnl->state |= CHNL_STATEEOS;

    /* Request IO from the DSP */
    io_request_chnl(chnl_mgr_obj->iomgr, pchnl,
            (CHNL_IS_INPUT(pchnl->chnl_mode) ? IO_INPUT :
             IO_OUTPUT), &mb_val);
    sched_dpc = true;
out:
    omap_mbox_enable_irq(dev_ctxt->mbox, IRQ_RX);
    spin_unlock_bh(&chnl_mgr_obj->chnl_mgr_lock);
    if (mb_val != 0)
        sm_interrupt_dsp(dev_ctxt, mb_val);

    /* Schedule a DPC, to do the actual data transfer */
    if (sched_dpc)
        iosm_schedule(chnl_mgr_obj->iomgr);

    return status;
}

/*
 *  ======== bridge_chnl_cancel_io ========
 *      Return all I/O requests to the client which have not yet been
 *      transferred.  The channel's I/O completion object is
 *      signalled, and all the I/O requests are queued as IOC's, with the
 *      status field set to CHNL_IOCSTATCANCEL.
 *      This call is typically used in abort situations, and is a prelude to
 *      chnl_close();
 */
int bridge_chnl_cancel_io(struct chnl_object *chnl_obj)
{
    struct chnl_object *pchnl = (struct chnl_object *)chnl_obj;
    u32 chnl_id = -1;
    s8 chnl_mode;
    struct chnl_irp *chirp, *tmp;
    struct chnl_mgr *chnl_mgr_obj = NULL;

    /* Check args: */
    if (!pchnl || !pchnl->chnl_mgr_obj)
        return -EFAULT;

    chnl_id = pchnl->chnl_id;
    chnl_mode = pchnl->chnl_mode;
    chnl_mgr_obj = pchnl->chnl_mgr_obj;

    /*  Mark this channel as cancelled, to prevent further IORequests or
     *  IORequests or dispatching. */
    spin_lock_bh(&chnl_mgr_obj->chnl_mgr_lock);

    pchnl->state |= CHNL_STATECANCEL;

    if (list_empty(&pchnl->io_requests)) {
        spin_unlock_bh(&chnl_mgr_obj->chnl_mgr_lock);
        return 0;
    }

    if (pchnl->chnl_type == CHNL_PCPY) {
        /* Indicate we have no more buffers available for transfer: */
        if (CHNL_IS_INPUT(pchnl->chnl_mode)) {
            io_cancel_chnl(chnl_mgr_obj->iomgr, chnl_id);
        } else {
            /* Record that we no longer have output buffers
             * available: */
            chnl_mgr_obj->output_mask &= ~(1 << chnl_id);
        }
    }
    /* Move all IOR's to IOC queue: */
    list_for_each_entry_safe(chirp, tmp, &pchnl->io_requests, link) {
        list_del(&chirp->link);
        chirp->byte_size = 0;
        chirp->status |= CHNL_IOCSTATCANCEL;
        list_add_tail(&chirp->link, &pchnl->io_completions);
        pchnl->cio_cs++;
        pchnl->cio_reqs--;
    }

    spin_unlock_bh(&chnl_mgr_obj->chnl_mgr_lock);

    return 0;
}

/*
 *  ======== bridge_chnl_close ========
 *  Purpose:
 *      Ensures all pending I/O on this channel is cancelled, discards all
 *      queued I/O completion notifications, then frees the resources allocated
 *      for this channel, and makes the corresponding logical channel id
 *      available for subsequent use.
 */
int bridge_chnl_close(struct chnl_object *chnl_obj)
{
    int status;
    struct chnl_object *pchnl = (struct chnl_object *)chnl_obj;

    /* Check args: */
    if (!pchnl)
        return -EFAULT;
    /* Cancel IO: this ensures no further IO requests or notifications */
    status = bridge_chnl_cancel_io(chnl_obj);
    if (status)
        return status;
    /* Invalidate channel object: Protects from CHNL_GetIOCompletion() */
    /* Free the slot in the channel manager: */
    pchnl->chnl_mgr_obj->channels[pchnl->chnl_id] = NULL;
    spin_lock_bh(&pchnl->chnl_mgr_obj->chnl_mgr_lock);
    pchnl->chnl_mgr_obj->open_channels -= 1;
    spin_unlock_bh(&pchnl->chnl_mgr_obj->chnl_mgr_lock);
    if (pchnl->ntfy_obj) {
        ntfy_delete(pchnl->ntfy_obj);
        kfree(pchnl->ntfy_obj);
        pchnl->ntfy_obj = NULL;
    }
    /* Reset channel event: (NOTE: user_event freed in user context) */
    if (pchnl->sync_event) {
        sync_reset_event(pchnl->sync_event);
        kfree(pchnl->sync_event);
        pchnl->sync_event = NULL;
    }
    /* Free I/O request and I/O completion queues: */
    free_chirp_list(&pchnl->io_completions);
    pchnl->cio_cs = 0;

    free_chirp_list(&pchnl->io_requests);
    pchnl->cio_reqs = 0;

    free_chirp_list(&pchnl->free_packets_list);

    /* Release channel object. */
    kfree(pchnl);

    return status;
}

/*
 *  ======== bridge_chnl_create ========
 *      Create a channel manager object, responsible for opening new channels
 *      and closing old ones for a given board.
 */
int bridge_chnl_create(struct chnl_mgr **channel_mgr,
                  struct dev_object *hdev_obj,
                  const struct chnl_mgrattrs *mgr_attrts)
{
    int status = 0;
    struct chnl_mgr *chnl_mgr_obj = NULL;
    u8 max_channels;

    /* Allocate channel manager object */
    chnl_mgr_obj = kzalloc(sizeof(struct chnl_mgr), GFP_KERNEL);
    if (chnl_mgr_obj) {
        /*
         * The max_channels attr must equal the # of supported chnls for
         * each transport(# chnls for PCPY = DDMA = ZCPY): i.e.
         *      mgr_attrts->max_channels = CHNL_MAXCHANNELS =
         *                       DDMA_MAXDDMACHNLS = DDMA_MAXZCPYCHNLS.
         */
        max_channels = CHNL_MAXCHANNELS + CHNL_MAXCHANNELS * CHNL_PCPY;
        /* Create array of channels */
        chnl_mgr_obj->channels = kzalloc(sizeof(struct chnl_object *)
                        * max_channels, GFP_KERNEL);
        if (chnl_mgr_obj->channels) {
            /* Initialize chnl_mgr object */
            chnl_mgr_obj->type = CHNL_TYPESM;
            chnl_mgr_obj->word_size = mgr_attrts->word_size;
            /* Total # chnls supported */
            chnl_mgr_obj->max_channels = max_channels;
            chnl_mgr_obj->open_channels = 0;
            chnl_mgr_obj->output_mask = 0;
            chnl_mgr_obj->last_output = 0;
            chnl_mgr_obj->dev_obj = hdev_obj;
            spin_lock_init(&chnl_mgr_obj->chnl_mgr_lock);
        } else {
            status = -ENOMEM;
        }
    } else {
        status = -ENOMEM;
    }

    if (status) {
        bridge_chnl_destroy(chnl_mgr_obj);
        *channel_mgr = NULL;
    } else {
        /* Return channel manager object to caller... */
        *channel_mgr = chnl_mgr_obj;
    }
    return status;
}

/*
 *  ======== bridge_chnl_destroy ========
 *  Purpose:
 *      Close all open channels, and destroy the channel manager.
 */
int bridge_chnl_destroy(struct chnl_mgr *hchnl_mgr)
{
    int status = 0;
    struct chnl_mgr *chnl_mgr_obj = hchnl_mgr;
    u32 chnl_id;

    if (hchnl_mgr) {
        /* Close all open channels: */
        for (chnl_id = 0; chnl_id < chnl_mgr_obj->max_channels;
             chnl_id++) {
            status =
                bridge_chnl_close(chnl_mgr_obj->channels
                          [chnl_id]);
            if (status)
                dev_dbg(bridge, "%s: Error status 0x%x\n",
                    __func__, status);
        }

        /* Free channel manager object: */
        kfree(chnl_mgr_obj->channels);

        /* Set hchnl_mgr to NULL in device object. */
        dev_set_chnl_mgr(chnl_mgr_obj->dev_obj, NULL);
        /* Free this Chnl Mgr object: */
        kfree(hchnl_mgr);
    } else {
        status = -EFAULT;
    }
    return status;
}

/*
 *  ======== bridge_chnl_flush_io ========
 *  purpose:
 *      Flushes all the outstanding data requests on a channel.
 */
int bridge_chnl_flush_io(struct chnl_object *chnl_obj, u32 timeout)
{
    int status = 0;
    struct chnl_object *pchnl = (struct chnl_object *)chnl_obj;
    s8 chnl_mode = -1;
    struct chnl_mgr *chnl_mgr_obj;
    struct chnl_ioc chnl_ioc_obj;
    /* Check args: */
    if (pchnl) {
        if ((timeout == CHNL_IOCNOWAIT)
            && CHNL_IS_OUTPUT(pchnl->chnl_mode)) {
            status = -EINVAL;
        } else {
            chnl_mode = pchnl->chnl_mode;
            chnl_mgr_obj = pchnl->chnl_mgr_obj;
        }
    } else {
        status = -EFAULT;
    }
    if (!status) {
        /* Note: Currently, if another thread continues to add IO
         * requests to this channel, this function will continue to
         * flush all such queued IO requests. */
        if (CHNL_IS_OUTPUT(chnl_mode)
            && (pchnl->chnl_type == CHNL_PCPY)) {
            /* Wait for IO completions, up to the specified
             * timeout: */
            while (!list_empty(&pchnl->io_requests) && !status) {
                status = bridge_chnl_get_ioc(chnl_obj,
                        timeout, &chnl_ioc_obj);
                if (status)
                    continue;

                if (chnl_ioc_obj.status & CHNL_IOCSTATTIMEOUT)
                    status = -ETIMEDOUT;

            }
        } else {
            status = bridge_chnl_cancel_io(chnl_obj);
            /* Now, leave the channel in the ready state: */
            pchnl->state &= ~CHNL_STATECANCEL;
        }
    }
    return status;
}

/*
 *  ======== bridge_chnl_get_info ========
 *  Purpose:
 *      Retrieve information related to a channel.
 */
int bridge_chnl_get_info(struct chnl_object *chnl_obj,
                 struct chnl_info *channel_info)
{
    int status = 0;
    struct chnl_object *pchnl = (struct chnl_object *)chnl_obj;
    if (channel_info != NULL) {
        if (pchnl) {
            /* Return the requested information: */
            channel_info->chnl_mgr = pchnl->chnl_mgr_obj;
            channel_info->event_obj = pchnl->user_event;
            channel_info->cnhl_id = pchnl->chnl_id;
            channel_info->mode = pchnl->chnl_mode;
            channel_info->bytes_tx = pchnl->bytes_moved;
            channel_info->process = pchnl->process;
            channel_info->sync_event = pchnl->sync_event;
            channel_info->cio_cs = pchnl->cio_cs;
            channel_info->cio_reqs = pchnl->cio_reqs;
            channel_info->state = pchnl->state;
        } else {
            status = -EFAULT;
        }
    } else {
        status = -EFAULT;
    }
    return status;
}

/*
 *  ======== bridge_chnl_get_ioc ========
 *      Optionally wait for I/O completion on a channel.  Dequeue an I/O
 *      completion record, which contains information about the completed
 *      I/O request.
 *      Note: Ensures Channel Invariant (see notes above).
 */
int bridge_chnl_get_ioc(struct chnl_object *chnl_obj, u32 timeout,
                struct chnl_ioc *chan_ioc)
{
    int status = 0;
    struct chnl_object *pchnl = (struct chnl_object *)chnl_obj;
    struct chnl_irp *chnl_packet_obj;
    int stat_sync;
    bool dequeue_ioc = true;
    struct chnl_ioc ioc = { NULL, 0, 0, 0, 0 };
    u8 *host_sys_buf = NULL;
    struct bridge_dev_context *dev_ctxt;
    struct dev_object *dev_obj;

    /* Check args: */
    if (!chan_ioc || !pchnl) {
        status = -EFAULT;
    } else if (timeout == CHNL_IOCNOWAIT) {
        if (list_empty(&pchnl->io_completions))
            status = -EREMOTEIO;

    }

    dev_obj = dev_get_first();
    dev_get_bridge_context(dev_obj, &dev_ctxt);
    if (!dev_ctxt)
        status = -EFAULT;

    if (status)
        goto func_end;

    ioc.status = CHNL_IOCSTATCOMPLETE;
    if (timeout !=
        CHNL_IOCNOWAIT && list_empty(&pchnl->io_completions)) {
        if (timeout == CHNL_IOCINFINITE)
            timeout = SYNC_INFINITE;

        stat_sync = sync_wait_on_event(pchnl->sync_event, timeout);
        if (stat_sync == -ETIME) {
            /* No response from DSP */
            ioc.status |= CHNL_IOCSTATTIMEOUT;
            dequeue_ioc = false;
        } else if (stat_sync == -EPERM) {
            /* This can occur when the user mode thread is
             * aborted (^C), or when _VWIN32_WaitSingleObject()
             * fails due to unknown causes. */
            /* Even though Wait failed, there may be something in
             * the Q: */
            if (list_empty(&pchnl->io_completions)) {
                ioc.status |= CHNL_IOCSTATCANCEL;
                dequeue_ioc = false;
            }
        }
    }
    /* See comment in AddIOReq */
    spin_lock_bh(&pchnl->chnl_mgr_obj->chnl_mgr_lock);
    omap_mbox_disable_irq(dev_ctxt->mbox, IRQ_RX);
    if (dequeue_ioc) {
        /* Dequeue IOC and set chan_ioc; */
        chnl_packet_obj = list_first_entry(&pchnl->io_completions,
                struct chnl_irp, link);
        list_del(&chnl_packet_obj->link);
        /* Update chan_ioc from channel state and chirp: */
        pchnl->cio_cs--;
        /*
         * If this is a zero-copy channel, then set IOC's pbuf
         * to the DSP's address. This DSP address will get
         * translated to user's virtual addr later.
         */
        host_sys_buf = chnl_packet_obj->host_sys_buf;
        ioc.buf = chnl_packet_obj->host_user_buf;
        ioc.byte_size = chnl_packet_obj->byte_size;
        ioc.buf_size = chnl_packet_obj->buf_size;
        ioc.arg = chnl_packet_obj->arg;
        ioc.status |= chnl_packet_obj->status;
        /* Place the used chirp on the free list: */
        list_add_tail(&chnl_packet_obj->link,
                &pchnl->free_packets_list);
    } else {
        ioc.buf = NULL;
        ioc.byte_size = 0;
        ioc.arg = 0;
        ioc.buf_size = 0;
    }
    /* Ensure invariant: If any IOC's are queued for this channel... */
    if (!list_empty(&pchnl->io_completions)) {
        /*  Since DSPStream_Reclaim() does not take a timeout
         *  parameter, we pass the stream's timeout value to
         *  bridge_chnl_get_ioc. We cannot determine whether or not
         *  we have waited in user mode. Since the stream's timeout
         *  value may be non-zero, we still have to set the event.
         *  Therefore, this optimization is taken out.
         *
         *  if (timeout == CHNL_IOCNOWAIT) {
         *    ... ensure event is set..
         *      sync_set_event(pchnl->sync_event);
         *  } */
        sync_set_event(pchnl->sync_event);
    } else {
        /* else, if list is empty, ensure event is reset. */
        sync_reset_event(pchnl->sync_event);
    }
    omap_mbox_enable_irq(dev_ctxt->mbox, IRQ_RX);
    spin_unlock_bh(&pchnl->chnl_mgr_obj->chnl_mgr_lock);
    if (dequeue_ioc
        && (pchnl->chnl_type == CHNL_PCPY && pchnl->chnl_id > 1)) {
        if (!(ioc.buf < (void *)USERMODE_ADDR))
            goto func_cont;

        /* If the addr is in user mode, then copy it */
        if (!host_sys_buf || !ioc.buf) {
            status = -EFAULT;
            goto func_cont;
        }
        if (!CHNL_IS_INPUT(pchnl->chnl_mode))
            goto func_cont1;

        /*host_user_buf */
        status = copy_to_user(ioc.buf, host_sys_buf, ioc.byte_size);
        if (status) {
            if (current->flags & PF_EXITING)
                status = 0;
        }
        if (status)
            status = -EFAULT;
func_cont1:
        kfree(host_sys_buf);
    }
func_cont:
    /* Update User's IOC block: */
    *chan_ioc = ioc;
func_end:
    return status;
}

/*
 *  ======== bridge_chnl_get_mgr_info ========
 *      Retrieve information related to the channel manager.
 */
int bridge_chnl_get_mgr_info(struct chnl_mgr *hchnl_mgr, u32 ch_id,
                 struct chnl_mgrinfo *mgr_info)
{
    struct chnl_mgr *chnl_mgr_obj = (struct chnl_mgr *)hchnl_mgr;

    if (!mgr_info || !hchnl_mgr)
        return -EFAULT;

    if (ch_id > CHNL_MAXCHANNELS)
        return -ECHRNG;

    /* Return the requested information: */
    mgr_info->chnl_obj = chnl_mgr_obj->channels[ch_id];
    mgr_info->open_channels = chnl_mgr_obj->open_channels;
    mgr_info->type = chnl_mgr_obj->type;
    /* total # of chnls */
    mgr_info->max_channels = chnl_mgr_obj->max_channels;

    return 0;
}

/*
 *  ======== bridge_chnl_idle ========
 *      Idles a particular channel.
 */
int bridge_chnl_idle(struct chnl_object *chnl_obj, u32 timeout,
                bool flush_data)
{
    s8 chnl_mode;
    struct chnl_mgr *chnl_mgr_obj;
    int status = 0;

    chnl_mode = chnl_obj->chnl_mode;
    chnl_mgr_obj = chnl_obj->chnl_mgr_obj;

    if (CHNL_IS_OUTPUT(chnl_mode) && !flush_data) {
        /* Wait for IO completions, up to the specified timeout: */
        status = bridge_chnl_flush_io(chnl_obj, timeout);
    } else {
        status = bridge_chnl_cancel_io(chnl_obj);

        /* Reset the byte count and put channel back in ready state. */
        chnl_obj->bytes_moved = 0;
        chnl_obj->state &= ~CHNL_STATECANCEL;
    }

    return status;
}

/*
 *  ======== bridge_chnl_open ========
 *      Open a new half-duplex channel to the DSP board.
 */
int bridge_chnl_open(struct chnl_object **chnl,
                struct chnl_mgr *hchnl_mgr, s8 chnl_mode,
                u32 ch_id, const struct chnl_attr *pattrs)
{
    int status = 0;
    struct chnl_mgr *chnl_mgr_obj = hchnl_mgr;
    struct chnl_object *pchnl = NULL;
    struct sync_object *sync_event = NULL;

    *chnl = NULL;

    /* Validate Args: */
    if (!pattrs->uio_reqs)
        return -EINVAL;

    if (!hchnl_mgr)
        return -EFAULT;

    if (ch_id != CHNL_PICKFREE) {
        if (ch_id >= chnl_mgr_obj->max_channels)
            return -ECHRNG;
        if (chnl_mgr_obj->channels[ch_id] != NULL)
            return -EALREADY;
    } else {
        /* Check for free channel */
        status = search_free_channel(chnl_mgr_obj, &ch_id);
        if (status)
            return status;
    }


    /* Create channel object: */
    pchnl = kzalloc(sizeof(struct chnl_object), GFP_KERNEL);
    if (!pchnl)
        return -ENOMEM;

    /* Protect queues from io_dpc: */
    pchnl->state = CHNL_STATECANCEL;

    /* Allocate initial IOR and IOC queues: */
    status = create_chirp_list(&pchnl->free_packets_list,
            pattrs->uio_reqs);
    if (status)
        goto out_err;

    INIT_LIST_HEAD(&pchnl->io_requests);
    INIT_LIST_HEAD(&pchnl->io_completions);

    pchnl->chnl_packets = pattrs->uio_reqs;
    pchnl->cio_cs = 0;
    pchnl->cio_reqs = 0;

    sync_event = kzalloc(sizeof(struct sync_object), GFP_KERNEL);
    if (!sync_event) {
        status = -ENOMEM;
        goto out_err;
    }
    sync_init_event(sync_event);

    pchnl->ntfy_obj = kmalloc(sizeof(struct ntfy_object), GFP_KERNEL);
    if (!pchnl->ntfy_obj) {
        status = -ENOMEM;
        goto out_err;
    }
    ntfy_init(pchnl->ntfy_obj);

    /* Initialize CHNL object fields: */
    pchnl->chnl_mgr_obj = chnl_mgr_obj;
    pchnl->chnl_id = ch_id;
    pchnl->chnl_mode = chnl_mode;
    pchnl->user_event = sync_event;
    pchnl->sync_event = sync_event;
    /* Get the process handle */
    pchnl->process = current->tgid;
    pchnl->cb_arg = 0;
    pchnl->bytes_moved = 0;
    /* Default to proc-copy */
    pchnl->chnl_type = CHNL_PCPY;

    /* Insert channel object in channel manager: */
    chnl_mgr_obj->channels[pchnl->chnl_id] = pchnl;
    spin_lock_bh(&chnl_mgr_obj->chnl_mgr_lock);
    chnl_mgr_obj->open_channels++;
    spin_unlock_bh(&chnl_mgr_obj->chnl_mgr_lock);
    /* Return result... */
    pchnl->state = CHNL_STATEREADY;
    *chnl = pchnl;

    return status;

out_err:
    /* Free memory */
    free_chirp_list(&pchnl->io_completions);
    free_chirp_list(&pchnl->io_requests);
    free_chirp_list(&pchnl->free_packets_list);

    kfree(sync_event);

    if (pchnl->ntfy_obj) {
        ntfy_delete(pchnl->ntfy_obj);
        kfree(pchnl->ntfy_obj);
        pchnl->ntfy_obj = NULL;
    }
    kfree(pchnl);

    return status;
}

/*
 *  ======== bridge_chnl_register_notify ========
 *      Registers for events on a particular channel.
 */
int bridge_chnl_register_notify(struct chnl_object *chnl_obj,
                    u32 event_mask, u32 notify_type,
                    struct dsp_notification *hnotification)
{
    int status = 0;


    if (event_mask)
        status = ntfy_register(chnl_obj->ntfy_obj, hnotification,
                        event_mask, notify_type);
    else
        status = ntfy_unregister(chnl_obj->ntfy_obj, hnotification);

    return status;
}

/*
 *  ======== create_chirp_list ========
 *  Purpose:
 *      Initialize a queue of channel I/O Request/Completion packets.
 *  Parameters:
 *      list:       Pointer to a list_head
 *      chirps:     Number of Chirps to allocate.
 *  Returns:
 *      0 if successful, error code otherwise.
 *  Requires:
 *  Ensures:
 */
static int create_chirp_list(struct list_head *list, u32 chirps)
{
    struct chnl_irp *chirp;
    u32 i;

    INIT_LIST_HEAD(list);

    /* Make N chirps and place on queue. */
    for (i = 0; i < chirps; i++) {
        chirp = kzalloc(sizeof(struct chnl_irp), GFP_KERNEL);
        if (!chirp)
            break;
        list_add_tail(&chirp->link, list);
    }

    /* If we couldn't allocate all chirps, free those allocated: */
    if (i != chirps) {
        free_chirp_list(list);
        return -ENOMEM;
    }

    return 0;
}

/*
 *  ======== free_chirp_list ========
 *  Purpose:
 *      Free the queue of Chirps.
 */
static void free_chirp_list(struct list_head *chirp_list)
{
    struct chnl_irp *chirp, *tmp;

    list_for_each_entry_safe(chirp, tmp, chirp_list, link) {
        list_del(&chirp->link);
        kfree(chirp);
    }
}

/*
 *  ======== search_free_channel ========
 *      Search for a free channel slot in the array of channel pointers.
 */
static int search_free_channel(struct chnl_mgr *chnl_mgr_obj,
                      u32 *chnl)
{
    int status = -ENOSR;
    u32 i;

    for (i = 0; i < chnl_mgr_obj->max_channels; i++) {
        if (chnl_mgr_obj->channels[i] == NULL) {
            status = 0;
            *chnl = i;
            break;
        }
    }

    return status;
}