/*
 * zfcp device driver
 *
 * Setup and helper functions to access QDIO.
 *
 * Copyright IBM Corporation 2002, 2008
 */

#define KMSG_COMPONENT "zfcp"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include "zfcp_ext.h"

#define QBUFF_PER_PAGE          (PAGE_SIZE / sizeof(struct qdio_buffer))

static int zfcp_qdio_buffers_enqueue(struct qdio_buffer **sbal)
{
        int pos;

        for (pos = 0; pos < QDIO_MAX_BUFFERS_PER_Q; pos += QBUFF_PER_PAGE) {
                sbal[pos] = (struct qdio_buffer *) get_zeroed_page(GFP_KERNEL);
                if (!sbal[pos])
                        return -ENOMEM;
        }
        for (pos = 0; pos < QDIO_MAX_BUFFERS_PER_Q; pos++)
                if (pos % QBUFF_PER_PAGE)
                        sbal[pos] = sbal[pos - 1] + 1;
        return 0;
}

static struct qdio_buffer_element *
zfcp_qdio_sbale(struct zfcp_qdio_queue *q, int sbal_idx, int sbale_idx)
{
        return &q->sbal[sbal_idx]->element[sbale_idx];
}

/**
 * zfcp_qdio_free - free memory used by request- and resposne queue
 * @adapter: pointer to the zfcp_adapter structure
 */
void zfcp_qdio_free(struct zfcp_adapter *adapter)
{
        struct qdio_buffer **sbal_req, **sbal_resp;
        int p;

        if (adapter->ccw_device)
                qdio_free(adapter->ccw_device);

        sbal_req = adapter->req_q.sbal;
        sbal_resp = adapter->resp_q.sbal;

        for (p = 0; p < QDIO_MAX_BUFFERS_PER_Q; p += QBUFF_PER_PAGE) {
                free_page((unsigned long) sbal_req[p]);
                free_page((unsigned long) sbal_resp[p]);
        }
}

static void zfcp_qdio_handler_error(struct zfcp_adapter *adapter, char *id)
{
        dev_warn(&adapter->ccw_device->dev, "A QDIO problem occurred\n");

        zfcp_erp_adapter_reopen(adapter,
                                ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED |
                                ZFCP_STATUS_COMMON_ERP_FAILED, id, NULL);
}

static void zfcp_qdio_zero_sbals(struct qdio_buffer *sbal[], int first, int cnt)
{
        int i, sbal_idx;

        for (i = first; i < first + cnt; i++) {
                sbal_idx = i % QDIO_MAX_BUFFERS_PER_Q;
                memset(sbal[sbal_idx], 0, sizeof(struct qdio_buffer));
        }
}

/* this needs to be called prior to updating the queue fill level */
static void zfcp_qdio_account(struct zfcp_adapter *adapter)
{
        ktime_t now;
        s64 span;
        int free, used;

        spin_lock(&adapter->qdio_stat_lock);
        now = ktime_get();
        span = ktime_us_delta(now, adapter->req_q_time);
        free = max(0, atomic_read(&adapter->req_q.count));
        used = QDIO_MAX_BUFFERS_PER_Q - free;
        adapter->req_q_util += used * span;
        adapter->req_q_time = now;
        spin_unlock(&adapter->qdio_stat_lock);
}

static void zfcp_qdio_int_req(struct ccw_device *cdev, unsigned int qdio_err,
                              int queue_no, int first, int count,
                              unsigned long parm)
{
        struct zfcp_adapter *adapter = (struct zfcp_adapter *) parm;
        struct zfcp_qdio_queue *queue = &adapter->req_q;

        if (unlikely(qdio_err)) {
                zfcp_hba_dbf_event_qdio(adapter, qdio_err, first, count);
                zfcp_qdio_handler_error(adapter, "qdireq1");
                return;
        }

        /* cleanup all SBALs being program-owned now */
        zfcp_qdio_zero_sbals(queue->sbal, first, count);

        zfcp_qdio_account(adapter);
        atomic_add(count, &queue->count);
        wake_up(&adapter->request_wq);
}

static void zfcp_qdio_reqid_check(struct zfcp_adapter *adapter,
                                  unsigned long req_id, int sbal_idx)
{
        struct zfcp_fsf_req *fsf_req;
        unsigned long flags;

        spin_lock_irqsave(&adapter->req_list_lock, flags);
        fsf_req = zfcp_reqlist_find(adapter, req_id);

        if (!fsf_req)
                /*
                 * Unknown request means that we have potentially memory
                 * corruption and must stop the machine immediatly.
                 */
                panic("error: unknown request id (%lx) on adapter %s.\n",
                      req_id, dev_name(&adapter->ccw_device->dev));

        zfcp_reqlist_remove(adapter, fsf_req);
        spin_unlock_irqrestore(&adapter->req_list_lock, flags);

        fsf_req->sbal_response = sbal_idx;
        fsf_req->qdio_inb_usage = atomic_read(&adapter->resp_q.count);
        zfcp_fsf_req_complete(fsf_req);
}

static void zfcp_qdio_resp_put_back(struct zfcp_adapter *adapter, int processed)
{
        struct zfcp_qdio_queue *queue = &adapter->resp_q;
        struct ccw_device *cdev = adapter->ccw_device;
        u8 count, start = queue->first;
        unsigned int retval;

        count = atomic_read(&queue->count) + processed;

        retval = do_QDIO(cdev, QDIO_FLAG_SYNC_INPUT, 0, start, count);

        if (unlikely(retval)) {
                atomic_set(&queue->count, count);
                /* FIXME: Recover this with an adapter reopen? */
        } else {
                queue->first += count;
                queue->first %= QDIO_MAX_BUFFERS_PER_Q;
                atomic_set(&queue->count, 0);
        }
}

static void zfcp_qdio_int_resp(struct ccw_device *cdev, unsigned int qdio_err,
                               int queue_no, int first, int count,
                               unsigned long parm)
{
        struct zfcp_adapter *adapter = (struct zfcp_adapter *) parm;
        struct zfcp_qdio_queue *queue = &adapter->resp_q;
        struct qdio_buffer_element *sbale;
        int sbal_idx, sbale_idx, sbal_no;

        if (unlikely(qdio_err)) {
                zfcp_hba_dbf_event_qdio(adapter, qdio_err, first, count);
                zfcp_qdio_handler_error(adapter, "qdires1");
                return;
        }

        /*
         * go through all SBALs from input queue currently
         * returned by QDIO layer
         */
        for (sbal_no = 0; sbal_no < count; sbal_no++) {
                sbal_idx = (first + sbal_no) % QDIO_MAX_BUFFERS_PER_Q;

                /* go through all SBALEs of SBAL */
                for (sbale_idx = 0; sbale_idx < QDIO_MAX_ELEMENTS_PER_BUFFER;
                     sbale_idx++) {
                        sbale = zfcp_qdio_sbale(queue, sbal_idx, sbale_idx);
                        zfcp_qdio_reqid_check(adapter,
                                              (unsigned long) sbale->addr,
                                              sbal_idx);
                        if (likely(sbale->flags & SBAL_FLAGS_LAST_ENTRY))
                                break;
                };

                if (unlikely(!(sbale->flags & SBAL_FLAGS_LAST_ENTRY)))
                        dev_warn(&adapter->ccw_device->dev,
                                 "A QDIO protocol error occurred, "
                                 "operations continue\n");
        }

        /*
         * put range of SBALs back to response queue
         * (including SBALs which have already been free before)
         */
        zfcp_qdio_resp_put_back(adapter, count);
}

/**
 * zfcp_qdio_sbale_req - return ptr to SBALE of req_q for a struct zfcp_fsf_req
 * @fsf_req: pointer to struct fsf_req
 * Returns: pointer to qdio_buffer_element (SBALE) structure
 */
struct qdio_buffer_element *zfcp_qdio_sbale_req(struct zfcp_fsf_req *req)
{
        return zfcp_qdio_sbale(&req->adapter->req_q, req->sbal_last, 0);
}

/**
 * zfcp_qdio_sbale_curr - return curr SBALE on req_q for a struct zfcp_fsf_req
 * @fsf_req: pointer to struct fsf_req
 * Returns: pointer to qdio_buffer_element (SBALE) structure
 */
struct qdio_buffer_element *zfcp_qdio_sbale_curr(struct zfcp_fsf_req *req)
{
        return zfcp_qdio_sbale(&req->adapter->req_q, req->sbal_last,
                               req->sbale_curr);
}

static void zfcp_qdio_sbal_limit(struct zfcp_fsf_req *fsf_req, int max_sbals)
{
        int count = atomic_read(&fsf_req->adapter->req_q.count);
        count = min(count, max_sbals);
        fsf_req->sbal_limit = (fsf_req->sbal_first + count - 1)
                                        % QDIO_MAX_BUFFERS_PER_Q;
}

static struct qdio_buffer_element *
zfcp_qdio_sbal_chain(struct zfcp_fsf_req *fsf_req, unsigned long sbtype)
{
        struct qdio_buffer_element *sbale;

        /* set last entry flag in current SBALE of current SBAL */
        sbale = zfcp_qdio_sbale_curr(fsf_req);
        sbale->flags |= SBAL_FLAGS_LAST_ENTRY;

        /* don't exceed last allowed SBAL */
        if (fsf_req->sbal_last == fsf_req->sbal_limit)
                return NULL;

        /* set chaining flag in first SBALE of current SBAL */
        sbale = zfcp_qdio_sbale_req(fsf_req);
        sbale->flags |= SBAL_FLAGS0_MORE_SBALS;

        /* calculate index of next SBAL */
        fsf_req->sbal_last++;
        fsf_req->sbal_last %= QDIO_MAX_BUFFERS_PER_Q;

        /* keep this requests number of SBALs up-to-date */
        fsf_req->sbal_number++;

        /* start at first SBALE of new SBAL */
        fsf_req->sbale_curr = 0;

        /* set storage-block type for new SBAL */
        sbale = zfcp_qdio_sbale_curr(fsf_req);
        sbale->flags |= sbtype;

        return sbale;
}

static struct qdio_buffer_element *
zfcp_qdio_sbale_next(struct zfcp_fsf_req *fsf_req, unsigned long sbtype)
{
        if (fsf_req->sbale_curr == ZFCP_LAST_SBALE_PER_SBAL)
                return zfcp_qdio_sbal_chain(fsf_req, sbtype);
        fsf_req->sbale_curr++;
        return zfcp_qdio_sbale_curr(fsf_req);
}

static void zfcp_qdio_undo_sbals(struct zfcp_fsf_req *fsf_req)
{
        struct qdio_buffer **sbal = fsf_req->adapter->req_q.sbal;
        int first = fsf_req->sbal_first;
        int last = fsf_req->sbal_last;
        int count = (last - first + QDIO_MAX_BUFFERS_PER_Q) %
                QDIO_MAX_BUFFERS_PER_Q + 1;
        zfcp_qdio_zero_sbals(sbal, first, count);
}

static int zfcp_qdio_fill_sbals(struct zfcp_fsf_req *fsf_req,
                                unsigned int sbtype, void *start_addr,
                                unsigned int total_length)
{
        struct qdio_buffer_element *sbale;
        unsigned long remaining, length;
        void *addr;

        /* split segment up */
        for (addr = start_addr, remaining = total_length; remaining > 0;
             addr += length, remaining -= length) {
                sbale = zfcp_qdio_sbale_next(fsf_req, sbtype);
                if (!sbale) {
                        atomic_inc(&fsf_req->adapter->qdio_outb_full);
                        zfcp_qdio_undo_sbals(fsf_req);
                        return -EINVAL;
                }

                /* new piece must not exceed next page boundary */
                length = min(remaining,
                             (PAGE_SIZE - ((unsigned long)addr &
                                           (PAGE_SIZE - 1))));
                sbale->addr = addr;
                sbale->length = length;
        }
        return 0;
}

/**
 * zfcp_qdio_sbals_from_sg - fill SBALs from scatter-gather list
 * @fsf_req: request to be processed
 * @sbtype: SBALE flags
 * @sg: scatter-gather list
 * @max_sbals: upper bound for number of SBALs to be used
 * Returns: number of bytes, or error (negativ)
 */
int zfcp_qdio_sbals_from_sg(struct zfcp_fsf_req *fsf_req, unsigned long sbtype,
                            struct scatterlist *sg, int max_sbals)
{
        struct qdio_buffer_element *sbale;
        int retval, bytes = 0;

        /* figure out last allowed SBAL */
        zfcp_qdio_sbal_limit(fsf_req, max_sbals);

        /* set storage-block type for this request */
        sbale = zfcp_qdio_sbale_req(fsf_req);
        sbale->flags |= sbtype;

        for (; sg; sg = sg_next(sg)) {
                retval = zfcp_qdio_fill_sbals(fsf_req, sbtype, sg_virt(sg),
                                              sg->length);
                if (retval < 0)
                        return retval;
                bytes += sg->length;
        }

        /* assume that no other SBALEs are to follow in the same SBAL */
        sbale = zfcp_qdio_sbale_curr(fsf_req);
        sbale->flags |= SBAL_FLAGS_LAST_ENTRY;

        return bytes;
}

/**
 * zfcp_qdio_send - set PCI flag in first SBALE and send req to QDIO
 * @fsf_req: pointer to struct zfcp_fsf_req
 * Returns: 0 on success, error otherwise
 */
int zfcp_qdio_send(struct zfcp_fsf_req *fsf_req)
{
        struct zfcp_adapter *adapter = fsf_req->adapter;
        struct zfcp_qdio_queue *req_q = &adapter->req_q;
        int first = fsf_req->sbal_first;
        int count = fsf_req->sbal_number;
        int retval;
        unsigned int qdio_flags = QDIO_FLAG_SYNC_OUTPUT;

        zfcp_qdio_account(adapter);

        retval = do_QDIO(adapter->ccw_device, qdio_flags, 0, first, count);
        if (unlikely(retval)) {
                zfcp_qdio_zero_sbals(req_q->sbal, first, count);
                return retval;
        }

        /* account for transferred buffers */
        atomic_sub(count, &req_q->count);
        req_q->first += count;
        req_q->first %= QDIO_MAX_BUFFERS_PER_Q;
        return 0;
}

/**
 * zfcp_qdio_allocate - allocate queue memory and initialize QDIO data
 * @adapter: pointer to struct zfcp_adapter
 * Returns: -ENOMEM on memory allocation error or return value from
 *          qdio_allocate
 */
int zfcp_qdio_allocate(struct zfcp_adapter *adapter)
{
        struct qdio_initialize *init_data;

        if (zfcp_qdio_buffers_enqueue(adapter->req_q.sbal) ||
                   zfcp_qdio_buffers_enqueue(adapter->resp_q.sbal))
                return -ENOMEM;

        init_data = &adapter->qdio_init_data;

        init_data->cdev = adapter->ccw_device;
        init_data->q_format = QDIO_ZFCP_QFMT;
        memcpy(init_data->adapter_name, dev_name(&adapter->ccw_device->dev), 8);
        ASCEBC(init_data->adapter_name, 8);
        init_data->qib_param_field_format = 0;
        init_data->qib_param_field = NULL;
        init_data->input_slib_elements = NULL;
        init_data->output_slib_elements = NULL;
        init_data->no_input_qs = 1;
        init_data->no_output_qs = 1;
        init_data->input_handler = zfcp_qdio_int_resp;
        init_data->output_handler = zfcp_qdio_int_req;
        init_data->int_parm = (unsigned long) adapter;
        init_data->flags = QDIO_INBOUND_0COPY_SBALS |
                        QDIO_OUTBOUND_0COPY_SBALS | QDIO_USE_OUTBOUND_PCIS;
        init_data->input_sbal_addr_array =
                        (void **) (adapter->resp_q.sbal);
        init_data->output_sbal_addr_array =
                        (void **) (adapter->req_q.sbal);

        return qdio_allocate(init_data);
}

/**
 * zfcp_close_qdio - close qdio queues for an adapter
 */
void zfcp_qdio_close(struct zfcp_adapter *adapter)
{
        struct zfcp_qdio_queue *req_q;
        int first, count;

        if (!(atomic_read(&adapter->status) & ZFCP_STATUS_ADAPTER_QDIOUP))
                return;

        /* clear QDIOUP flag, thus do_QDIO is not called during qdio_shutdown */
        req_q = &adapter->req_q;
        spin_lock_bh(&adapter->req_q_lock);
        atomic_clear_mask(ZFCP_STATUS_ADAPTER_QDIOUP, &adapter->status);
        spin_unlock_bh(&adapter->req_q_lock);

        qdio_shutdown(adapter->ccw_device, QDIO_FLAG_CLEANUP_USING_CLEAR);

        /* cleanup used outbound sbals */
        count = atomic_read(&req_q->count);
        if (count < QDIO_MAX_BUFFERS_PER_Q) {
                first = (req_q->first + count) % QDIO_MAX_BUFFERS_PER_Q;
                count = QDIO_MAX_BUFFERS_PER_Q - count;
                zfcp_qdio_zero_sbals(req_q->sbal, first, count);
        }
        req_q->first = 0;
        atomic_set(&req_q->count, 0);
        adapter->resp_q.first = 0;
        atomic_set(&adapter->resp_q.count, 0);
}

/**
 * zfcp_qdio_open - prepare and initialize response queue
 * @adapter: pointer to struct zfcp_adapter
 * Returns: 0 on success, otherwise -EIO
 */
int zfcp_qdio_open(struct zfcp_adapter *adapter)
{
        struct qdio_buffer_element *sbale;
        int cc;

        if (atomic_read(&adapter->status) & ZFCP_STATUS_ADAPTER_QDIOUP)
                return -EIO;

        if (qdio_establish(&adapter->qdio_init_data))
                goto failed_establish;

        if (qdio_activate(adapter->ccw_device))
                goto failed_qdio;

        for (cc = 0; cc < QDIO_MAX_BUFFERS_PER_Q; cc++) {
                sbale = &(adapter->resp_q.sbal[cc]->element[0]);
                sbale->length = 0;
                sbale->flags = SBAL_FLAGS_LAST_ENTRY;
                sbale->addr = NULL;
        }

        if (do_QDIO(adapter->ccw_device, QDIO_FLAG_SYNC_INPUT, 0, 0,
                     QDIO_MAX_BUFFERS_PER_Q))
                goto failed_qdio;

        /* set index of first avalable SBALS / number of available SBALS */
        adapter->req_q.first = 0;
        atomic_set(&adapter->req_q.count, QDIO_MAX_BUFFERS_PER_Q);

        return 0;

failed_qdio:
        qdio_shutdown(adapter->ccw_device, QDIO_FLAG_CLEANUP_USING_CLEAR);
failed_establish:
        dev_err(&adapter->ccw_device->dev,
                "Setting up the QDIO connection to the FCP adapter failed\n");
        return -EIO;
}