// SPDX-License-Identifier: GPL-2.0
/*
 * zfcp device driver
 *
 * Setup and helper functions to access QDIO.
 *
 * Copyright IBM Corp. 2002, 2020
 */

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

#include <linux/lockdep.h>
#include <linux/slab.h>
#include <linux/module.h>
#include "zfcp_ext.h"
#include "zfcp_qdio.h"

static bool enable_multibuffer = true;
module_param_named(datarouter, enable_multibuffer, bool, 0400);
MODULE_PARM_DESC(datarouter, "Enable hardware data router support (default on)");

#define ZFCP_QDIO_REQUEST_RESCAN_MSECS  (MSEC_PER_SEC * 10)
#define ZFCP_QDIO_REQUEST_SCAN_MSECS    MSEC_PER_SEC

static void zfcp_qdio_handler_error(struct zfcp_qdio *qdio, char *dbftag,
                                    unsigned int qdio_err)
{
        struct zfcp_adapter *adapter = qdio->adapter;

        dev_warn(&adapter->ccw_device->dev, "A QDIO problem occurred\n");

        if (qdio_err & QDIO_ERROR_SLSB_STATE) {
                zfcp_qdio_siosl(adapter);
                zfcp_erp_adapter_shutdown(adapter, 0, dbftag);
                return;
        }
        zfcp_erp_adapter_reopen(adapter,
                                ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED |
                                ZFCP_STATUS_COMMON_ERP_FAILED, dbftag);
}

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 inline void zfcp_qdio_account(struct zfcp_qdio *qdio)
{
        unsigned long long now, span;
        int used;

        now = get_tod_clock_monotonic();
        span = (now - qdio->req_q_time) >> 12;
        used = QDIO_MAX_BUFFERS_PER_Q - atomic_read(&qdio->req_q_free);
        qdio->req_q_util += used * span;
        qdio->req_q_time = now;
}

static void zfcp_qdio_int_req(struct ccw_device *cdev, unsigned int qdio_err,
                              int queue_no, int idx, int count,
                              unsigned long parm)
{
        struct zfcp_qdio *qdio = (struct zfcp_qdio *) parm;

        if (unlikely(qdio_err)) {
                zfcp_qdio_handler_error(qdio, "qdireq1", qdio_err);
                return;
        }
}

static void zfcp_qdio_request_tasklet(struct tasklet_struct *tasklet)
{
        struct zfcp_qdio *qdio = from_tasklet(qdio, tasklet, request_tasklet);
        struct ccw_device *cdev = qdio->adapter->ccw_device;
        unsigned int start, error;
        int completed;

        completed = qdio_inspect_queue(cdev, 0, false, &start, &error);
        if (completed > 0) {
                if (error) {
                        zfcp_qdio_handler_error(qdio, "qdreqt1", error);
                } else {
                        /* cleanup all SBALs being program-owned now */
                        zfcp_qdio_zero_sbals(qdio->req_q, start, completed);

                        spin_lock_irq(&qdio->stat_lock);
                        zfcp_qdio_account(qdio);
                        spin_unlock_irq(&qdio->stat_lock);
                        atomic_add(completed, &qdio->req_q_free);
                        wake_up(&qdio->req_q_wq);
                }
        }

        if (atomic_read(&qdio->req_q_free) < QDIO_MAX_BUFFERS_PER_Q)
                timer_reduce(&qdio->request_timer,
                             jiffies + msecs_to_jiffies(ZFCP_QDIO_REQUEST_RESCAN_MSECS));
}

static void zfcp_qdio_request_timer(struct timer_list *timer)
{
        struct zfcp_qdio *qdio = from_timer(qdio, timer, request_timer);

        tasklet_schedule(&qdio->request_tasklet);
}

static void zfcp_qdio_int_resp(struct ccw_device *cdev, unsigned int qdio_err,
                               int queue_no, int idx, int count,
                               unsigned long parm)
{
        struct zfcp_qdio *qdio = (struct zfcp_qdio *) parm;
        struct zfcp_adapter *adapter = qdio->adapter;
        int sbal_no, sbal_idx;

        if (unlikely(qdio_err)) {
                if (zfcp_adapter_multi_buffer_active(adapter)) {
                        void *pl[ZFCP_QDIO_MAX_SBALS_PER_REQ + 1];
                        struct qdio_buffer_element *sbale;
                        u64 req_id;
                        u8 scount;

                        memset(pl, 0,
                               ZFCP_QDIO_MAX_SBALS_PER_REQ * sizeof(void *));
                        sbale = qdio->res_q[idx]->element;
                        req_id = sbale->addr;
                        scount = min(sbale->scount + 1,
                                     ZFCP_QDIO_MAX_SBALS_PER_REQ + 1);
                                     /* incl. signaling SBAL */

                        for (sbal_no = 0; sbal_no < scount; sbal_no++) {
                                sbal_idx = (idx + sbal_no) %
                                        QDIO_MAX_BUFFERS_PER_Q;
                                pl[sbal_no] = qdio->res_q[sbal_idx];
                        }
                        zfcp_dbf_hba_def_err(adapter, req_id, scount, pl);
                }
                zfcp_qdio_handler_error(qdio, "qdires1", qdio_err);
                return;
        }

        /*
         * go through all SBALs from input queue currently
         * returned by QDIO layer
         */
        for (sbal_no = 0; sbal_no < count; sbal_no++) {
                sbal_idx = (idx + sbal_no) % QDIO_MAX_BUFFERS_PER_Q;
                /* go through all SBALEs of SBAL */
                zfcp_fsf_reqid_check(qdio, sbal_idx);
        }

        /*
         * put SBALs back to response queue
         */
        if (do_QDIO(cdev, QDIO_FLAG_SYNC_INPUT, 0, idx, count, NULL))
                zfcp_erp_adapter_reopen(qdio->adapter, 0, "qdires2");
}

static void zfcp_qdio_irq_tasklet(struct tasklet_struct *tasklet)
{
        struct zfcp_qdio *qdio = from_tasklet(qdio, tasklet, irq_tasklet);
        struct ccw_device *cdev = qdio->adapter->ccw_device;
        unsigned int start, error;
        int completed;

        if (atomic_read(&qdio->req_q_free) < QDIO_MAX_BUFFERS_PER_Q)
                tasklet_schedule(&qdio->request_tasklet);

        /* Check the Response Queue: */
        completed = qdio_inspect_queue(cdev, 0, true, &start, &error);
        if (completed < 0)
                return;
        if (completed > 0)
                zfcp_qdio_int_resp(cdev, error, 0, start, completed,
                                   (unsigned long) qdio);

        if (qdio_start_irq(cdev))
                /* More work pending: */
                tasklet_schedule(&qdio->irq_tasklet);
}

static void zfcp_qdio_poll(struct ccw_device *cdev, unsigned long data)
{
        struct zfcp_qdio *qdio = (struct zfcp_qdio *) data;

        tasklet_schedule(&qdio->irq_tasklet);
}

static struct qdio_buffer_element *
zfcp_qdio_sbal_chain(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req)
{
        struct qdio_buffer_element *sbale;

        /* set last entry flag in current SBALE of current SBAL */
        sbale = zfcp_qdio_sbale_curr(qdio, q_req);
        sbale->eflags |= SBAL_EFLAGS_LAST_ENTRY;

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

        /* set chaining flag in first SBALE of current SBAL */
        sbale = zfcp_qdio_sbale_req(qdio, q_req);
        sbale->sflags |= SBAL_SFLAGS0_MORE_SBALS;

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

        /* keep this requests number of SBALs up-to-date */
        q_req->sbal_number++;
        BUG_ON(q_req->sbal_number > ZFCP_QDIO_MAX_SBALS_PER_REQ);

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

        /* set storage-block type for new SBAL */
        sbale = zfcp_qdio_sbale_curr(qdio, q_req);
        sbale->sflags |= q_req->sbtype;

        return sbale;
}

static struct qdio_buffer_element *
zfcp_qdio_sbale_next(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req)
{
        if (q_req->sbale_curr == qdio->max_sbale_per_sbal - 1)
                return zfcp_qdio_sbal_chain(qdio, q_req);
        q_req->sbale_curr++;
        return zfcp_qdio_sbale_curr(qdio, q_req);
}

/**
 * zfcp_qdio_sbals_from_sg - fill SBALs from scatter-gather list
 * @qdio: pointer to struct zfcp_qdio
 * @q_req: pointer to struct zfcp_qdio_req
 * @sg: scatter-gather list
 * Returns: zero or -EINVAL on error
 */
int zfcp_qdio_sbals_from_sg(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req,
                            struct scatterlist *sg)
{
        struct qdio_buffer_element *sbale;

        /* set storage-block type for this request */
        sbale = zfcp_qdio_sbale_req(qdio, q_req);
        sbale->sflags |= q_req->sbtype;

        for (; sg; sg = sg_next(sg)) {
                sbale = zfcp_qdio_sbale_next(qdio, q_req);
                if (!sbale) {
                        atomic_inc(&qdio->req_q_full);
                        zfcp_qdio_zero_sbals(qdio->req_q, q_req->sbal_first,
                                             q_req->sbal_number);
                        return -EINVAL;
                }
                sbale->addr = sg_phys(sg);
                sbale->length = sg->length;
        }
        return 0;
}

static int zfcp_qdio_sbal_check(struct zfcp_qdio *qdio)
{
        if (atomic_read(&qdio->req_q_free) ||
            !(atomic_read(&qdio->adapter->status) & ZFCP_STATUS_ADAPTER_QDIOUP))
                return 1;
        return 0;
}

/**
 * zfcp_qdio_sbal_get - get free sbal in request queue, wait if necessary
 * @qdio: pointer to struct zfcp_qdio
 *
 * The req_q_lock must be held by the caller of this function, and
 * this function may only be called from process context; it will
 * sleep when waiting for a free sbal.
 *
 * Returns: 0 on success, -EIO if there is no free sbal after waiting.
 */
int zfcp_qdio_sbal_get(struct zfcp_qdio *qdio)
{
        long ret;

        ret = wait_event_interruptible_lock_irq_timeout(qdio->req_q_wq,
                       zfcp_qdio_sbal_check(qdio), qdio->req_q_lock, 5 * HZ);

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

        if (ret > 0)
                return 0;

        if (!ret) {
                atomic_inc(&qdio->req_q_full);
                /* assume hanging outbound queue, try queue recovery */
                zfcp_erp_adapter_reopen(qdio->adapter, 0, "qdsbg_1");
        }

        return -EIO;
}

/**
 * zfcp_qdio_send - send req to QDIO
 * @qdio: pointer to struct zfcp_qdio
 * @q_req: pointer to struct zfcp_qdio_req
 * Returns: 0 on success, error otherwise
 */
int zfcp_qdio_send(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req)
{
        int retval;
        u8 sbal_number = q_req->sbal_number;

        /*
         * This should actually be a spin_lock_bh(stat_lock), to protect against
         * Request Queue completion processing in tasklet context.
         * But we can't do so (and are safe), as we always get called with IRQs
         * disabled by spin_lock_irq[save](req_q_lock).
         */
        lockdep_assert_irqs_disabled();
        spin_lock(&qdio->stat_lock);
        zfcp_qdio_account(qdio);
        spin_unlock(&qdio->stat_lock);

        atomic_sub(sbal_number, &qdio->req_q_free);

        retval = do_QDIO(qdio->adapter->ccw_device, QDIO_FLAG_SYNC_OUTPUT, 0,
                         q_req->sbal_first, sbal_number, NULL);

        if (unlikely(retval)) {
                /* Failed to submit the IO, roll back our modifications. */
                atomic_add(sbal_number, &qdio->req_q_free);
                zfcp_qdio_zero_sbals(qdio->req_q, q_req->sbal_first,
                                     sbal_number);
                return retval;
        }

        if (atomic_read(&qdio->req_q_free) <= 2 * ZFCP_QDIO_MAX_SBALS_PER_REQ)
                tasklet_schedule(&qdio->request_tasklet);
        else
                timer_reduce(&qdio->request_timer,
                             jiffies + msecs_to_jiffies(ZFCP_QDIO_REQUEST_SCAN_MSECS));

        /* account for transferred buffers */
        qdio->req_q_idx += sbal_number;
        qdio->req_q_idx %= QDIO_MAX_BUFFERS_PER_Q;

        return 0;
}

/**
 * zfcp_qdio_allocate - allocate queue memory and initialize QDIO data
 * @qdio: pointer to struct zfcp_qdio
 * Returns: -ENOMEM on memory allocation error or return value from
 *          qdio_allocate
 */
static int zfcp_qdio_allocate(struct zfcp_qdio *qdio)
{
        int ret;

        ret = qdio_alloc_buffers(qdio->req_q, QDIO_MAX_BUFFERS_PER_Q);
        if (ret)
                return -ENOMEM;

        ret = qdio_alloc_buffers(qdio->res_q, QDIO_MAX_BUFFERS_PER_Q);
        if (ret)
                goto free_req_q;

        init_waitqueue_head(&qdio->req_q_wq);

        ret = qdio_allocate(qdio->adapter->ccw_device, 1, 1);
        if (ret)
                goto free_res_q;

        return 0;

free_res_q:
        qdio_free_buffers(qdio->res_q, QDIO_MAX_BUFFERS_PER_Q);
free_req_q:
        qdio_free_buffers(qdio->req_q, QDIO_MAX_BUFFERS_PER_Q);
        return ret;
}

/**
 * zfcp_close_qdio - close qdio queues for an adapter
 * @qdio: pointer to structure zfcp_qdio
 */
void zfcp_qdio_close(struct zfcp_qdio *qdio)
{
        struct zfcp_adapter *adapter = qdio->adapter;
        int idx, count;

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

        /* clear QDIOUP flag, thus do_QDIO is not called during qdio_shutdown */
        spin_lock_irq(&qdio->req_q_lock);
        atomic_andnot(ZFCP_STATUS_ADAPTER_QDIOUP, &adapter->status);
        spin_unlock_irq(&qdio->req_q_lock);

        wake_up(&qdio->req_q_wq);

        tasklet_disable(&qdio->irq_tasklet);
        tasklet_disable(&qdio->request_tasklet);
        del_timer_sync(&qdio->request_timer);
        qdio_stop_irq(adapter->ccw_device);
        qdio_shutdown(adapter->ccw_device, QDIO_FLAG_CLEANUP_USING_CLEAR);

        /* cleanup used outbound sbals */
        count = atomic_read(&qdio->req_q_free);
        if (count < QDIO_MAX_BUFFERS_PER_Q) {
                idx = (qdio->req_q_idx + count) % QDIO_MAX_BUFFERS_PER_Q;
                count = QDIO_MAX_BUFFERS_PER_Q - count;
                zfcp_qdio_zero_sbals(qdio->req_q, idx, count);
        }
        qdio->req_q_idx = 0;
        atomic_set(&qdio->req_q_free, 0);
}

void zfcp_qdio_shost_update(struct zfcp_adapter *const adapter,
                            const struct zfcp_qdio *const qdio)
{
        struct Scsi_Host *const shost = adapter->scsi_host;

        if (shost == NULL)
                return;

        shost->sg_tablesize = qdio->max_sbale_per_req;
        shost->max_sectors = qdio->max_sbale_per_req * 8;
}

/**
 * zfcp_qdio_open - prepare and initialize response queue
 * @qdio: pointer to struct zfcp_qdio
 * Returns: 0 on success, otherwise -EIO
 */
int zfcp_qdio_open(struct zfcp_qdio *qdio)
{
        struct qdio_buffer **input_sbals[1] = {qdio->res_q};
        struct qdio_buffer **output_sbals[1] = {qdio->req_q};
        struct qdio_buffer_element *sbale;
        struct qdio_initialize init_data = {0};
        struct zfcp_adapter *adapter = qdio->adapter;
        struct ccw_device *cdev = adapter->ccw_device;
        struct qdio_ssqd_desc ssqd;
        int cc;

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

        atomic_andnot(ZFCP_STATUS_ADAPTER_SIOSL_ISSUED,
                          &qdio->adapter->status);

        init_data.q_format = QDIO_ZFCP_QFMT;
        init_data.qib_rflags = QIB_RFLAGS_ENABLE_DATA_DIV;
        if (enable_multibuffer)
                init_data.qdr_ac |= QDR_AC_MULTI_BUFFER_ENABLE;
        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.irq_poll = zfcp_qdio_poll;
        init_data.int_parm = (unsigned long) qdio;
        init_data.input_sbal_addr_array = input_sbals;
        init_data.output_sbal_addr_array = output_sbals;

        if (qdio_establish(cdev, &init_data))
                goto failed_establish;

        if (qdio_get_ssqd_desc(cdev, &ssqd))
                goto failed_qdio;

        if (ssqd.qdioac2 & CHSC_AC2_DATA_DIV_ENABLED)
                atomic_or(ZFCP_STATUS_ADAPTER_DATA_DIV_ENABLED,
                                &qdio->adapter->status);

        if (ssqd.qdioac2 & CHSC_AC2_MULTI_BUFFER_ENABLED) {
                atomic_or(ZFCP_STATUS_ADAPTER_MB_ACT, &adapter->status);
                qdio->max_sbale_per_sbal = QDIO_MAX_ELEMENTS_PER_BUFFER;
        } else {
                atomic_andnot(ZFCP_STATUS_ADAPTER_MB_ACT, &adapter->status);
                qdio->max_sbale_per_sbal = QDIO_MAX_ELEMENTS_PER_BUFFER - 1;
        }

        qdio->max_sbale_per_req =
                ZFCP_QDIO_MAX_SBALS_PER_REQ * qdio->max_sbale_per_sbal
                - 2;
        if (qdio_activate(cdev))
                goto failed_qdio;

        for (cc = 0; cc < QDIO_MAX_BUFFERS_PER_Q; cc++) {
                sbale = &(qdio->res_q[cc]->element[0]);
                sbale->length = 0;
                sbale->eflags = SBAL_EFLAGS_LAST_ENTRY;
                sbale->sflags = 0;
                sbale->addr = 0;
        }

        if (do_QDIO(cdev, QDIO_FLAG_SYNC_INPUT, 0, 0, QDIO_MAX_BUFFERS_PER_Q,
                    NULL))
                goto failed_qdio;

        /* set index of first available SBALS / number of available SBALS */
        qdio->req_q_idx = 0;
        atomic_set(&qdio->req_q_free, QDIO_MAX_BUFFERS_PER_Q);
        atomic_or(ZFCP_STATUS_ADAPTER_QDIOUP, &qdio->adapter->status);

        /* Enable processing for Request Queue completions: */
        tasklet_enable(&qdio->request_tasklet);
        /* Enable processing for QDIO interrupts: */
        tasklet_enable(&qdio->irq_tasklet);
        /* This results in a qdio_start_irq(): */
        tasklet_schedule(&qdio->irq_tasklet);

        zfcp_qdio_shost_update(adapter, qdio);

        return 0;

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

void zfcp_qdio_destroy(struct zfcp_qdio *qdio)
{
        if (!qdio)
                return;

        tasklet_kill(&qdio->irq_tasklet);
        tasklet_kill(&qdio->request_tasklet);

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

        qdio_free_buffers(qdio->req_q, QDIO_MAX_BUFFERS_PER_Q);
        qdio_free_buffers(qdio->res_q, QDIO_MAX_BUFFERS_PER_Q);
        kfree(qdio);
}

int zfcp_qdio_setup(struct zfcp_adapter *adapter)
{
        struct zfcp_qdio *qdio;

        qdio = kzalloc(sizeof(struct zfcp_qdio), GFP_KERNEL);
        if (!qdio)
                return -ENOMEM;

        qdio->adapter = adapter;

        if (zfcp_qdio_allocate(qdio)) {
                kfree(qdio);
                return -ENOMEM;
        }

        spin_lock_init(&qdio->req_q_lock);
        spin_lock_init(&qdio->stat_lock);
        timer_setup(&qdio->request_timer, zfcp_qdio_request_timer, 0);
        tasklet_setup(&qdio->irq_tasklet, zfcp_qdio_irq_tasklet);
        tasklet_setup(&qdio->request_tasklet, zfcp_qdio_request_tasklet);
        tasklet_disable(&qdio->irq_tasklet);
        tasklet_disable(&qdio->request_tasklet);

        adapter->qdio = qdio;
        return 0;
}

/**
 * zfcp_qdio_siosl - Trigger logging in FCP channel
 * @adapter: The zfcp_adapter where to trigger logging
 *
 * Call the cio siosl function to trigger hardware logging.  This
 * wrapper function sets a flag to ensure hardware logging is only
 * triggered once before going through qdio shutdown.
 *
 * The triggers are always run from qdio tasklet context, so no
 * additional synchronization is necessary.
 */
void zfcp_qdio_siosl(struct zfcp_adapter *adapter)
{
        int rc;

        if (atomic_read(&adapter->status) & ZFCP_STATUS_ADAPTER_SIOSL_ISSUED)
                return;

        rc = ccw_device_siosl(adapter->ccw_device);
        if (!rc)
                atomic_or(ZFCP_STATUS_ADAPTER_SIOSL_ISSUED,
                                &adapter->status);
}