/*
 *  CCW device PGID and path verification I/O handling.
 *
 *    Copyright IBM Corp. 2002, 2009
 *    Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
 *               Martin Schwidefsky <schwidefsky@de.ibm.com>
 *               Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
 */

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <asm/ccwdev.h>
#include <asm/cio.h>

#include "cio.h"
#include "cio_debug.h"
#include "device.h"
#include "io_sch.h"

#define PGID_RETRIES    256
#define PGID_TIMEOUT    (10 * HZ)

static void verify_start(struct ccw_device *cdev);

/*
 * Process path verification data and report result.
 */
static void verify_done(struct ccw_device *cdev, int rc)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_dev_id *id = &cdev->private->dev_id;
        int mpath = cdev->private->flags.mpath;
        int pgroup = cdev->private->flags.pgroup;

        if (rc)
                goto out;
        /* Ensure consistent multipathing state at device and channel. */
        if (sch->config.mp != mpath) {
                sch->config.mp = mpath;
                rc = cio_commit_config(sch);
        }
out:
        CIO_MSG_EVENT(2, "vrfy: device 0.%x.%04x: rc=%d pgroup=%d mpath=%d "
                         "vpm=%02x\n", id->ssid, id->devno, rc, pgroup, mpath,
                         sch->vpm);
        ccw_device_verify_done(cdev, rc);
}

/*
 * Create channel program to perform a NOOP.
 */
static void nop_build_cp(struct ccw_device *cdev)
{
        struct ccw_request *req = &cdev->private->req;
        struct ccw1 *cp = cdev->private->iccws;

        cp->cmd_code    = CCW_CMD_NOOP;
        cp->cda         = 0;
        cp->count       = 0;
        cp->flags       = CCW_FLAG_SLI;
        req->cp         = cp;
}

/*
 * Perform NOOP on a single path.
 */
static void nop_do(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_request *req = &cdev->private->req;

        req->lpm = lpm_adjust(req->lpm, sch->schib.pmcw.pam & sch->opm &
                              ~cdev->private->path_noirq_mask);
        if (!req->lpm)
                goto out_nopath;
        nop_build_cp(cdev);
        ccw_request_start(cdev);
        return;

out_nopath:
        verify_done(cdev, sch->vpm ? 0 : -EACCES);
}

/*
 * Adjust NOOP I/O status.
 */
static enum io_status nop_filter(struct ccw_device *cdev, void *data,
                                 struct irb *irb, enum io_status status)
{
        /* Only subchannel status might indicate a path error. */
        if (status == IO_STATUS_ERROR && irb->scsw.cmd.cstat == 0)
                return IO_DONE;
        return status;
}

/*
 * Process NOOP request result for a single path.
 */
static void nop_callback(struct ccw_device *cdev, void *data, int rc)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_request *req = &cdev->private->req;

        switch (rc) {
        case 0:
                sch->vpm |= req->lpm;
                break;
        case -ETIME:
                cdev->private->path_noirq_mask |= req->lpm;
                break;
        case -EACCES:
                cdev->private->path_notoper_mask |= req->lpm;
                break;
        default:
                goto err;
        }
        /* Continue on the next path. */
        req->lpm >>= 1;
        nop_do(cdev);
        return;

err:
        verify_done(cdev, rc);
}

/*
 * Create channel program to perform SET PGID on a single path.
 */
static void spid_build_cp(struct ccw_device *cdev, u8 fn)
{
        struct ccw_request *req = &cdev->private->req;
        struct ccw1 *cp = cdev->private->iccws;
        int i = pathmask_to_pos(req->lpm);
        struct pgid *pgid = &cdev->private->pgid[i];

        pgid->inf.fc    = fn;
        cp->cmd_code    = CCW_CMD_SET_PGID;
        cp->cda         = (u32) (addr_t) pgid;
        cp->count       = sizeof(*pgid);
        cp->flags       = CCW_FLAG_SLI;
        req->cp         = cp;
}

static void pgid_wipeout_callback(struct ccw_device *cdev, void *data, int rc)
{
        if (rc) {
                /* We don't know the path groups' state. Abort. */
                verify_done(cdev, rc);
                return;
        }
        /*
         * Path groups have been reset. Restart path verification but
         * leave paths in path_noirq_mask out.
         */
        cdev->private->flags.pgid_unknown = 0;
        verify_start(cdev);
}

/*
 * Reset pathgroups and restart path verification, leave unusable paths out.
 */
static void pgid_wipeout_start(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_dev_id *id = &cdev->private->dev_id;
        struct ccw_request *req = &cdev->private->req;
        u8 fn;

        CIO_MSG_EVENT(2, "wipe: device 0.%x.%04x: pvm=%02x nim=%02x\n",
                      id->ssid, id->devno, cdev->private->pgid_valid_mask,
                      cdev->private->path_noirq_mask);

        /* Initialize request data. */
        memset(req, 0, sizeof(*req));
        req->timeout    = PGID_TIMEOUT;
        req->maxretries = PGID_RETRIES;
        req->lpm        = sch->schib.pmcw.pam;
        req->callback   = pgid_wipeout_callback;
        fn = SPID_FUNC_DISBAND;
        if (cdev->private->flags.mpath)
                fn |= SPID_FUNC_MULTI_PATH;
        spid_build_cp(cdev, fn);
        ccw_request_start(cdev);
}

/*
 * Perform establish/resign SET PGID on a single path.
 */
static void spid_do(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_request *req = &cdev->private->req;
        u8 fn;

        /* Use next available path that is not already in correct state. */
        req->lpm = lpm_adjust(req->lpm, cdev->private->pgid_todo_mask);
        if (!req->lpm)
                goto out_nopath;
        /* Channel program setup. */
        if (req->lpm & sch->opm)
                fn = SPID_FUNC_ESTABLISH;
        else
                fn = SPID_FUNC_RESIGN;
        if (cdev->private->flags.mpath)
                fn |= SPID_FUNC_MULTI_PATH;
        spid_build_cp(cdev, fn);
        ccw_request_start(cdev);
        return;

out_nopath:
        if (cdev->private->flags.pgid_unknown) {
                /* At least one SPID could be partially done. */
                pgid_wipeout_start(cdev);
                return;
        }
        verify_done(cdev, sch->vpm ? 0 : -EACCES);
}

/*
 * Process SET PGID request result for a single path.
 */
static void spid_callback(struct ccw_device *cdev, void *data, int rc)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_request *req = &cdev->private->req;

        switch (rc) {
        case 0:
                sch->vpm |= req->lpm & sch->opm;
                break;
        case -ETIME:
                cdev->private->flags.pgid_unknown = 1;
                cdev->private->path_noirq_mask |= req->lpm;
                break;
        case -EACCES:
                cdev->private->path_notoper_mask |= req->lpm;
                break;
        case -EOPNOTSUPP:
                if (cdev->private->flags.mpath) {
                        /* Try without multipathing. */
                        cdev->private->flags.mpath = 0;
                        goto out_restart;
                }
                /* Try without pathgrouping. */
                cdev->private->flags.pgroup = 0;
                goto out_restart;
        default:
                goto err;
        }
        req->lpm >>= 1;
        spid_do(cdev);
        return;

out_restart:
        verify_start(cdev);
        return;
err:
        verify_done(cdev, rc);
}

static void spid_start(struct ccw_device *cdev)
{
        struct ccw_request *req = &cdev->private->req;

        /* Initialize request data. */
        memset(req, 0, sizeof(*req));
        req->timeout    = PGID_TIMEOUT;
        req->maxretries = PGID_RETRIES;
        req->lpm        = 0x80;
        req->singlepath = 1;
        req->callback   = spid_callback;
        spid_do(cdev);
}

static int pgid_is_reset(struct pgid *p)
{
        char *c;

        for (c = (char *)p + 1; c < (char *)(p + 1); c++) {
                if (*c != 0)
                        return 0;
        }
        return 1;
}

static int pgid_cmp(struct pgid *p1, struct pgid *p2)
{
        return memcmp((char *) p1 + 1, (char *) p2 + 1,
                      sizeof(struct pgid) - 1);
}

/*
 * Determine pathgroup state from PGID data.
 */
static void pgid_analyze(struct ccw_device *cdev, struct pgid **p,
                         int *mismatch, u8 *reserved, u8 *reset)
{
        struct pgid *pgid = &cdev->private->pgid[0];
        struct pgid *first = NULL;
        int lpm;
        int i;

        *mismatch = 0;
        *reserved = 0;
        *reset = 0;
        for (i = 0, lpm = 0x80; i < 8; i++, pgid++, lpm >>= 1) {
                if ((cdev->private->pgid_valid_mask & lpm) == 0)
                        continue;
                if (pgid->inf.ps.state2 == SNID_STATE2_RESVD_ELSE)
                        *reserved |= lpm;
                if (pgid_is_reset(pgid)) {
                        *reset |= lpm;
                        continue;
                }
                if (!first) {
                        first = pgid;
                        continue;
                }
                if (pgid_cmp(pgid, first) != 0)
                        *mismatch = 1;
        }
        if (!first)
                first = &channel_subsystems[0]->global_pgid;
        *p = first;
}

static u8 pgid_to_donepm(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct pgid *pgid;
        int i;
        int lpm;
        u8 donepm = 0;

        /* Set bits for paths which are already in the target state. */
        for (i = 0; i < 8; i++) {
                lpm = 0x80 >> i;
                if ((cdev->private->pgid_valid_mask & lpm) == 0)
                        continue;
                pgid = &cdev->private->pgid[i];
                if (sch->opm & lpm) {
                        if (pgid->inf.ps.state1 != SNID_STATE1_GROUPED)
                                continue;
                } else {
                        if (pgid->inf.ps.state1 != SNID_STATE1_UNGROUPED)
                                continue;
                }
                if (cdev->private->flags.mpath) {
                        if (pgid->inf.ps.state3 != SNID_STATE3_MULTI_PATH)
                                continue;
                } else {
                        if (pgid->inf.ps.state3 != SNID_STATE3_SINGLE_PATH)
                                continue;
                }
                donepm |= lpm;
        }

        return donepm;
}

static void pgid_fill(struct ccw_device *cdev, struct pgid *pgid)
{
        int i;

        for (i = 0; i < 8; i++)
                memcpy(&cdev->private->pgid[i], pgid, sizeof(struct pgid));
}

/*
 * Process SENSE PGID data and report result.
 */
static void snid_done(struct ccw_device *cdev, int rc)
{
        struct ccw_dev_id *id = &cdev->private->dev_id;
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct pgid *pgid;
        int mismatch = 0;
        u8 reserved = 0;
        u8 reset = 0;
        u8 donepm;

        if (rc)
                goto out;
        pgid_analyze(cdev, &pgid, &mismatch, &reserved, &reset);
        if (reserved == cdev->private->pgid_valid_mask)
                rc = -EUSERS;
        else if (mismatch)
                rc = -EOPNOTSUPP;
        else {
                donepm = pgid_to_donepm(cdev);
                sch->vpm = donepm & sch->opm;
                cdev->private->pgid_reset_mask |= reset;
                cdev->private->pgid_todo_mask &=
                        ~(donepm | cdev->private->path_noirq_mask);
                pgid_fill(cdev, pgid);
        }
out:
        CIO_MSG_EVENT(2, "snid: device 0.%x.%04x: rc=%d pvm=%02x vpm=%02x "
                      "todo=%02x mism=%d rsvd=%02x reset=%02x\n", id->ssid,
                      id->devno, rc, cdev->private->pgid_valid_mask, sch->vpm,
                      cdev->private->pgid_todo_mask, mismatch, reserved, reset);
        switch (rc) {
        case 0:
                if (cdev->private->flags.pgid_unknown) {
                        pgid_wipeout_start(cdev);
                        return;
                }
                /* Anything left to do? */
                if (cdev->private->pgid_todo_mask == 0) {
                        verify_done(cdev, sch->vpm == 0 ? -EACCES : 0);
                        return;
                }
                /* Perform path-grouping. */
                spid_start(cdev);
                break;
        case -EOPNOTSUPP:
                /* Path-grouping not supported. */
                cdev->private->flags.pgroup = 0;
                cdev->private->flags.mpath = 0;
                verify_start(cdev);
                break;
        default:
                verify_done(cdev, rc);
        }
}

/*
 * Create channel program to perform a SENSE PGID on a single path.
 */
static void snid_build_cp(struct ccw_device *cdev)
{
        struct ccw_request *req = &cdev->private->req;
        struct ccw1 *cp = cdev->private->iccws;
        int i = pathmask_to_pos(req->lpm);

        /* Channel program setup. */
        cp->cmd_code    = CCW_CMD_SENSE_PGID;
        cp->cda         = (u32) (addr_t) &cdev->private->pgid[i];
        cp->count       = sizeof(struct pgid);
        cp->flags       = CCW_FLAG_SLI;
        req->cp         = cp;
}

/*
 * Perform SENSE PGID on a single path.
 */
static void snid_do(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_request *req = &cdev->private->req;
        int ret;

        req->lpm = lpm_adjust(req->lpm, sch->schib.pmcw.pam &
                              ~cdev->private->path_noirq_mask);
        if (!req->lpm)
                goto out_nopath;
        snid_build_cp(cdev);
        ccw_request_start(cdev);
        return;

out_nopath:
        if (cdev->private->pgid_valid_mask)
                ret = 0;
        else if (cdev->private->path_noirq_mask)
                ret = -ETIME;
        else
                ret = -EACCES;
        snid_done(cdev, ret);
}

/*
 * Process SENSE PGID request result for single path.
 */
static void snid_callback(struct ccw_device *cdev, void *data, int rc)
{
        struct ccw_request *req = &cdev->private->req;

        switch (rc) {
        case 0:
                cdev->private->pgid_valid_mask |= req->lpm;
                break;
        case -ETIME:
                cdev->private->flags.pgid_unknown = 1;
                cdev->private->path_noirq_mask |= req->lpm;
                break;
        case -EACCES:
                cdev->private->path_notoper_mask |= req->lpm;
                break;
        default:
                goto err;
        }
        /* Continue on the next path. */
        req->lpm >>= 1;
        snid_do(cdev);
        return;

err:
        snid_done(cdev, rc);
}

/*
 * Perform path verification.
 */
static void verify_start(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_request *req = &cdev->private->req;
        struct ccw_dev_id *devid = &cdev->private->dev_id;

        sch->vpm = 0;
        sch->lpm = sch->schib.pmcw.pam;

        /* Initialize PGID data. */
        memset(cdev->private->pgid, 0, sizeof(cdev->private->pgid));
        cdev->private->pgid_valid_mask = 0;
        cdev->private->pgid_todo_mask = sch->schib.pmcw.pam;
        cdev->private->path_notoper_mask = 0;

        /* Initialize request data. */
        memset(req, 0, sizeof(*req));
        req->timeout    = PGID_TIMEOUT;
        req->maxretries = PGID_RETRIES;
        req->lpm        = 0x80;
        req->singlepath = 1;
        if (cdev->private->flags.pgroup) {
                CIO_TRACE_EVENT(4, "snid");
                CIO_HEX_EVENT(4, devid, sizeof(*devid));
                req->callback   = snid_callback;
                snid_do(cdev);
        } else {
                CIO_TRACE_EVENT(4, "nop");
                CIO_HEX_EVENT(4, devid, sizeof(*devid));
                req->filter     = nop_filter;
                req->callback   = nop_callback;
                nop_do(cdev);
        }
}

/**
 * ccw_device_verify_start - perform path verification
 * @cdev: ccw device
 *
 * Perform an I/O on each available channel path to @cdev to determine which
 * paths are operational. The resulting path mask is stored in sch->vpm.
 * If device options specify pathgrouping, establish a pathgroup for the
 * operational paths. When finished, call ccw_device_verify_done with a
 * return code specifying the result.
 */
void ccw_device_verify_start(struct ccw_device *cdev)
{
        CIO_TRACE_EVENT(4, "vrfy");
        CIO_HEX_EVENT(4, &cdev->private->dev_id, sizeof(cdev->private->dev_id));
        /*
         * Initialize pathgroup and multipath state with target values.
         * They may change in the course of path verification.
         */
        cdev->private->flags.pgroup = cdev->private->options.pgroup;
        cdev->private->flags.mpath = cdev->private->options.mpath;
        cdev->private->flags.doverify = 0;
        cdev->private->path_noirq_mask = 0;
        verify_start(cdev);
}

/*
 * Process disband SET PGID request result.
 */
static void disband_callback(struct ccw_device *cdev, void *data, int rc)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_dev_id *id = &cdev->private->dev_id;

        if (rc)
                goto out;
        /* Ensure consistent multipathing state at device and channel. */
        cdev->private->flags.mpath = 0;
        if (sch->config.mp) {
                sch->config.mp = 0;
                rc = cio_commit_config(sch);
        }
out:
        CIO_MSG_EVENT(0, "disb: device 0.%x.%04x: rc=%d\n", id->ssid, id->devno,
                      rc);
        ccw_device_disband_done(cdev, rc);
}

/**
 * ccw_device_disband_start - disband pathgroup
 * @cdev: ccw device
 *
 * Execute a SET PGID channel program on @cdev to disband a previously
 * established pathgroup. When finished, call ccw_device_disband_done with
 * a return code specifying the result.
 */
void ccw_device_disband_start(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_request *req = &cdev->private->req;
        u8 fn;

        CIO_TRACE_EVENT(4, "disb");
        CIO_HEX_EVENT(4, &cdev->private->dev_id, sizeof(cdev->private->dev_id));
        /* Request setup. */
        memset(req, 0, sizeof(*req));
        req->timeout    = PGID_TIMEOUT;
        req->maxretries = PGID_RETRIES;
        req->lpm        = sch->schib.pmcw.pam & sch->opm;
        req->singlepath = 1;
        req->callback   = disband_callback;
        fn = SPID_FUNC_DISBAND;
        if (cdev->private->flags.mpath)
                fn |= SPID_FUNC_MULTI_PATH;
        spid_build_cp(cdev, fn);
        ccw_request_start(cdev);
}

struct stlck_data {
        struct completion done;
        int rc;
};

static void stlck_build_cp(struct ccw_device *cdev, void *buf1, void *buf2)
{
        struct ccw_request *req = &cdev->private->req;
        struct ccw1 *cp = cdev->private->iccws;

        cp[0].cmd_code = CCW_CMD_STLCK;
        cp[0].cda = (u32) (addr_t) buf1;
        cp[0].count = 32;
        cp[0].flags = CCW_FLAG_CC;
        cp[1].cmd_code = CCW_CMD_RELEASE;
        cp[1].cda = (u32) (addr_t) buf2;
        cp[1].count = 32;
        cp[1].flags = 0;
        req->cp = cp;
}

static void stlck_callback(struct ccw_device *cdev, void *data, int rc)
{
        struct stlck_data *sdata = data;

        sdata->rc = rc;
        complete(&sdata->done);
}

/**
 * ccw_device_stlck_start - perform unconditional release
 * @cdev: ccw device
 * @data: data pointer to be passed to ccw_device_stlck_done
 * @buf1: data pointer used in channel program
 * @buf2: data pointer used in channel program
 *
 * Execute a channel program on @cdev to release an existing PGID reservation.
 */
static void ccw_device_stlck_start(struct ccw_device *cdev, void *data,
                                   void *buf1, void *buf2)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct ccw_request *req = &cdev->private->req;

        CIO_TRACE_EVENT(4, "stlck");
        CIO_HEX_EVENT(4, &cdev->private->dev_id, sizeof(cdev->private->dev_id));
        /* Request setup. */
        memset(req, 0, sizeof(*req));
        req->timeout    = PGID_TIMEOUT;
        req->maxretries = PGID_RETRIES;
        req->lpm        = sch->schib.pmcw.pam & sch->opm;
        req->data       = data;
        req->callback   = stlck_callback;
        stlck_build_cp(cdev, buf1, buf2);
        ccw_request_start(cdev);
}

/*
 * Perform unconditional reserve + release.
 */
int ccw_device_stlck(struct ccw_device *cdev)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        struct stlck_data data;
        u8 *buffer;
        int rc;

        /* Check if steal lock operation is valid for this device. */
        if (cdev->drv) {
                if (!cdev->private->options.force)
                        return -EINVAL;
        }
        buffer = kzalloc(64, GFP_DMA | GFP_KERNEL);
        if (!buffer)
                return -ENOMEM;
        init_completion(&data.done);
        data.rc = -EIO;
        spin_lock_irq(sch->lock);
        rc = cio_enable_subchannel(sch, (u32) (addr_t) sch);
        if (rc)
                goto out_unlock;
        /* Perform operation. */
        cdev->private->state = DEV_STATE_STEAL_LOCK;
        ccw_device_stlck_start(cdev, &data, &buffer[0], &buffer[32]);
        spin_unlock_irq(sch->lock);
        /* Wait for operation to finish. */
        if (wait_for_completion_interruptible(&data.done)) {
                /* Got a signal. */
                spin_lock_irq(sch->lock);
                ccw_request_cancel(cdev);
                spin_unlock_irq(sch->lock);
                wait_for_completion(&data.done);
        }
        rc = data.rc;
        /* Check results. */
        spin_lock_irq(sch->lock);
        cio_disable_subchannel(sch);
        cdev->private->state = DEV_STATE_BOXED;
out_unlock:
        spin_unlock_irq(sch->lock);
        kfree(buffer);

        return rc;
}