x86/unwinder: Handle stack overflows more gracefully

[linux/fpc-iii.git] / drivers / s390 / cio / cio.c

/*
 *   S/390 common I/O routines -- low level i/o calls
 *
 *    Copyright IBM Corp. 1999, 2008
 *    Author(s): Ingo Adlung (adlung@de.ibm.com)
 *               Cornelia Huck (cornelia.huck@de.ibm.com)
 *               Arnd Bergmann (arndb@de.ibm.com)
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

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

#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <asm/cio.h>
#include <asm/delay.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>
#include <asm/setup.h>
#include <asm/reset.h>
#include <asm/ipl.h>
#include <asm/chpid.h>
#include <asm/airq.h>
#include <asm/isc.h>
#include <linux/sched/cputime.h>
#include <asm/fcx.h>
#include <asm/nmi.h>
#include <asm/crw.h>
#include "cio.h"
#include "css.h"
#include "chsc.h"
#include "ioasm.h"
#include "io_sch.h"
#include "blacklist.h"
#include "cio_debug.h"
#include "chp.h"
#include "trace.h"

debug_info_t *cio_debug_msg_id;
debug_info_t *cio_debug_trace_id;
debug_info_t *cio_debug_crw_id;

DEFINE_PER_CPU_ALIGNED(struct irb, cio_irb);
EXPORT_PER_CPU_SYMBOL(cio_irb);

/*
 * Function: cio_debug_init
 * Initializes three debug logs for common I/O:
 * - cio_msg logs generic cio messages
 * - cio_trace logs the calling of different functions
 * - cio_crw logs machine check related cio messages
 */
static int __init cio_debug_init(void)
{
        cio_debug_msg_id = debug_register("cio_msg", 16, 1, 11 * sizeof(long));
        if (!cio_debug_msg_id)
                goto out_unregister;
        debug_register_view(cio_debug_msg_id, &debug_sprintf_view);
        debug_set_level(cio_debug_msg_id, 2);
        cio_debug_trace_id = debug_register("cio_trace", 16, 1, 16);
        if (!cio_debug_trace_id)
                goto out_unregister;
        debug_register_view(cio_debug_trace_id, &debug_hex_ascii_view);
        debug_set_level(cio_debug_trace_id, 2);
        cio_debug_crw_id = debug_register("cio_crw", 8, 1, 8 * sizeof(long));
        if (!cio_debug_crw_id)
                goto out_unregister;
        debug_register_view(cio_debug_crw_id, &debug_sprintf_view);
        debug_set_level(cio_debug_crw_id, 4);
        return 0;

out_unregister:
        debug_unregister(cio_debug_msg_id);
        debug_unregister(cio_debug_trace_id);
        debug_unregister(cio_debug_crw_id);
        return -1;
}

arch_initcall (cio_debug_init);

int cio_set_options(struct subchannel *sch, int flags)
{
        struct io_subchannel_private *priv = to_io_private(sch);

        priv->options.suspend = (flags & DOIO_ALLOW_SUSPEND) != 0;
        priv->options.prefetch = (flags & DOIO_DENY_PREFETCH) != 0;
        priv->options.inter = (flags & DOIO_SUPPRESS_INTER) != 0;
        return 0;
}

static int
cio_start_handle_notoper(struct subchannel *sch, __u8 lpm)
{
        char dbf_text[15];

        if (lpm != 0)
                sch->lpm &= ~lpm;
        else
                sch->lpm = 0;

        CIO_MSG_EVENT(2, "cio_start: 'not oper' status for "
                      "subchannel 0.%x.%04x!\n", sch->schid.ssid,
                      sch->schid.sch_no);

        if (cio_update_schib(sch))
                return -ENODEV;

        sprintf(dbf_text, "no%s", dev_name(&sch->dev));
        CIO_TRACE_EVENT(0, dbf_text);
        CIO_HEX_EVENT(0, &sch->schib, sizeof (struct schib));

        return (sch->lpm ? -EACCES : -ENODEV);
}

int
cio_start_key (struct subchannel *sch,  /* subchannel structure */
               struct ccw1 * cpa,       /* logical channel prog addr */
               __u8 lpm,                /* logical path mask */
               __u8 key)                /* storage key */
{
        struct io_subchannel_private *priv = to_io_private(sch);
        union orb *orb = &priv->orb;
        int ccode;

        CIO_TRACE_EVENT(5, "stIO");
        CIO_TRACE_EVENT(5, dev_name(&sch->dev));

        memset(orb, 0, sizeof(union orb));
        /* sch is always under 2G. */
        orb->cmd.intparm = (u32)(addr_t)sch;
        orb->cmd.fmt = 1;

        orb->cmd.pfch = priv->options.prefetch == 0;
        orb->cmd.spnd = priv->options.suspend;
        orb->cmd.ssic = priv->options.suspend && priv->options.inter;
        orb->cmd.lpm = (lpm != 0) ? lpm : sch->lpm;
        /*
         * for 64 bit we always support 64 bit IDAWs with 4k page size only
         */
        orb->cmd.c64 = 1;
        orb->cmd.i2k = 0;
        orb->cmd.key = key >> 4;
        /* issue "Start Subchannel" */
        orb->cmd.cpa = (__u32) __pa(cpa);
        ccode = ssch(sch->schid, orb);

        /* process condition code */
        CIO_HEX_EVENT(5, &ccode, sizeof(ccode));

        switch (ccode) {
        case 0:
                /*
                 * initialize device status information
                 */
                sch->schib.scsw.cmd.actl |= SCSW_ACTL_START_PEND;
                return 0;
        case 1:         /* status pending */
        case 2:         /* busy */
                return -EBUSY;
        case 3:         /* device/path not operational */
                return cio_start_handle_notoper(sch, lpm);
        default:
                return ccode;
        }
}
EXPORT_SYMBOL_GPL(cio_start_key);

int
cio_start (struct subchannel *sch, struct ccw1 *cpa, __u8 lpm)
{
        return cio_start_key(sch, cpa, lpm, PAGE_DEFAULT_KEY);
}
EXPORT_SYMBOL_GPL(cio_start);

/*
 * resume suspended I/O operation
 */
int
cio_resume (struct subchannel *sch)
{
        int ccode;

        CIO_TRACE_EVENT(4, "resIO");
        CIO_TRACE_EVENT(4, dev_name(&sch->dev));

        ccode = rsch (sch->schid);

        CIO_HEX_EVENT(4, &ccode, sizeof(ccode));

        switch (ccode) {
        case 0:
                sch->schib.scsw.cmd.actl |= SCSW_ACTL_RESUME_PEND;
                return 0;
        case 1:
                return -EBUSY;
        case 2:
                return -EINVAL;
        default:
                /*
                 * useless to wait for request completion
                 *  as device is no longer operational !
                 */
                return -ENODEV;
        }
}
EXPORT_SYMBOL_GPL(cio_resume);

/*
 * halt I/O operation
 */
int
cio_halt(struct subchannel *sch)
{
        int ccode;

        if (!sch)
                return -ENODEV;

        CIO_TRACE_EVENT(2, "haltIO");
        CIO_TRACE_EVENT(2, dev_name(&sch->dev));

        /*
         * Issue "Halt subchannel" and process condition code
         */
        ccode = hsch (sch->schid);

        CIO_HEX_EVENT(2, &ccode, sizeof(ccode));

        switch (ccode) {
        case 0:
                sch->schib.scsw.cmd.actl |= SCSW_ACTL_HALT_PEND;
                return 0;
        case 1:         /* status pending */
        case 2:         /* busy */
                return -EBUSY;
        default:                /* device not operational */
                return -ENODEV;
        }
}
EXPORT_SYMBOL_GPL(cio_halt);

/*
 * Clear I/O operation
 */
int
cio_clear(struct subchannel *sch)
{
        int ccode;

        if (!sch)
                return -ENODEV;

        CIO_TRACE_EVENT(2, "clearIO");
        CIO_TRACE_EVENT(2, dev_name(&sch->dev));

        /*
         * Issue "Clear subchannel" and process condition code
         */
        ccode = csch (sch->schid);

        CIO_HEX_EVENT(2, &ccode, sizeof(ccode));

        switch (ccode) {
        case 0:
                sch->schib.scsw.cmd.actl |= SCSW_ACTL_CLEAR_PEND;
                return 0;
        default:                /* device not operational */
                return -ENODEV;
        }
}
EXPORT_SYMBOL_GPL(cio_clear);

/*
 * Function: cio_cancel
 * Issues a "Cancel Subchannel" on the specified subchannel
 * Note: We don't need any fancy intparms and flags here
 *       since xsch is executed synchronously.
 * Only for common I/O internal use as for now.
 */
int
cio_cancel (struct subchannel *sch)
{
        int ccode;

        if (!sch)
                return -ENODEV;

        CIO_TRACE_EVENT(2, "cancelIO");
        CIO_TRACE_EVENT(2, dev_name(&sch->dev));

        ccode = xsch (sch->schid);

        CIO_HEX_EVENT(2, &ccode, sizeof(ccode));

        switch (ccode) {
        case 0:         /* success */
                /* Update information in scsw. */
                if (cio_update_schib(sch))
                        return -ENODEV;
                return 0;
        case 1:         /* status pending */
                return -EBUSY;
        case 2:         /* not applicable */
                return -EINVAL;
        default:        /* not oper */
                return -ENODEV;
        }
}
EXPORT_SYMBOL_GPL(cio_cancel);

/**
 * cio_cancel_halt_clear - Cancel running I/O by performing cancel, halt
 * and clear ordinally if subchannel is valid.
 * @sch: subchannel on which to perform the cancel_halt_clear operation
 * @iretry: the number of the times remained to retry the next operation
 *
 * This should be called repeatedly since halt/clear are asynchronous
 * operations. We do one try with cio_cancel, three tries with cio_halt,
 * 255 tries with cio_clear. The caller should initialize @iretry with
 * the value 255 for its first call to this, and keep using the same
 * @iretry in the subsequent calls until it gets a non -EBUSY return.
 *
 * Returns 0 if device now idle, -ENODEV for device not operational,
 * -EBUSY if an interrupt is expected (either from halt/clear or from a
 * status pending), and -EIO if out of retries.
 */
int cio_cancel_halt_clear(struct subchannel *sch, int *iretry)
{
        int ret;

        if (cio_update_schib(sch))
                return -ENODEV;
        if (!sch->schib.pmcw.ena)
                /* Not operational -> done. */
                return 0;
        /* Stage 1: cancel io. */
        if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_HALT_PEND) &&
            !(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
                if (!scsw_is_tm(&sch->schib.scsw)) {
                        ret = cio_cancel(sch);
                        if (ret != -EINVAL)
                                return ret;
                }
                /*
                 * Cancel io unsuccessful or not applicable (transport mode).
                 * Continue with asynchronous instructions.
                 */
                *iretry = 3;    /* 3 halt retries. */
        }
        /* Stage 2: halt io. */
        if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
                if (*iretry) {
                        *iretry -= 1;
                        ret = cio_halt(sch);
                        if (ret != -EBUSY)
                                return (ret == 0) ? -EBUSY : ret;
                }
                /* Halt io unsuccessful. */
                *iretry = 255;  /* 255 clear retries. */
        }
        /* Stage 3: clear io. */
        if (*iretry) {
                *iretry -= 1;
                ret = cio_clear(sch);
                return (ret == 0) ? -EBUSY : ret;
        }
        /* Function was unsuccessful */
        return -EIO;
}
EXPORT_SYMBOL_GPL(cio_cancel_halt_clear);

static void cio_apply_config(struct subchannel *sch, struct schib *schib)
{
        schib->pmcw.intparm = sch->config.intparm;
        schib->pmcw.mbi = sch->config.mbi;
        schib->pmcw.isc = sch->config.isc;
        schib->pmcw.ena = sch->config.ena;
        schib->pmcw.mme = sch->config.mme;
        schib->pmcw.mp = sch->config.mp;
        schib->pmcw.csense = sch->config.csense;
        schib->pmcw.mbfc = sch->config.mbfc;
        if (sch->config.mbfc)
                schib->mba = sch->config.mba;
}

static int cio_check_config(struct subchannel *sch, struct schib *schib)
{
        return (schib->pmcw.intparm == sch->config.intparm) &&
                (schib->pmcw.mbi == sch->config.mbi) &&
                (schib->pmcw.isc == sch->config.isc) &&
                (schib->pmcw.ena == sch->config.ena) &&
                (schib->pmcw.mme == sch->config.mme) &&
                (schib->pmcw.mp == sch->config.mp) &&
                (schib->pmcw.csense == sch->config.csense) &&
                (schib->pmcw.mbfc == sch->config.mbfc) &&
                (!sch->config.mbfc || (schib->mba == sch->config.mba));
}

/*
 * cio_commit_config - apply configuration to the subchannel
 */
int cio_commit_config(struct subchannel *sch)
{
        int ccode, retry, ret = 0;
        struct schib schib;
        struct irb irb;

        if (stsch(sch->schid, &schib) || !css_sch_is_valid(&schib))
                return -ENODEV;

        for (retry = 0; retry < 5; retry++) {
                /* copy desired changes to local schib */
                cio_apply_config(sch, &schib);
                ccode = msch(sch->schid, &schib);
                if (ccode < 0) /* -EIO if msch gets a program check. */
                        return ccode;
                switch (ccode) {
                case 0: /* successful */
                        if (stsch(sch->schid, &schib) ||
                            !css_sch_is_valid(&schib))
                                return -ENODEV;
                        if (cio_check_config(sch, &schib)) {
                                /* commit changes from local schib */
                                memcpy(&sch->schib, &schib, sizeof(schib));
                                return 0;
                        }
                        ret = -EAGAIN;
                        break;
                case 1: /* status pending */
                        ret = -EBUSY;
                        if (tsch(sch->schid, &irb))
                                return ret;
                        break;
                case 2: /* busy */
                        udelay(100); /* allow for recovery */
                        ret = -EBUSY;
                        break;
                case 3: /* not operational */
                        return -ENODEV;
                }
        }
        return ret;
}
EXPORT_SYMBOL_GPL(cio_commit_config);

/**
 * cio_update_schib - Perform stsch and update schib if subchannel is valid.
 * @sch: subchannel on which to perform stsch
 * Return zero on success, -ENODEV otherwise.
 */
int cio_update_schib(struct subchannel *sch)
{
        struct schib schib;

        if (stsch(sch->schid, &schib) || !css_sch_is_valid(&schib))
                return -ENODEV;

        memcpy(&sch->schib, &schib, sizeof(schib));
        return 0;
}
EXPORT_SYMBOL_GPL(cio_update_schib);

/**
 * cio_enable_subchannel - enable a subchannel.
 * @sch: subchannel to be enabled
 * @intparm: interruption parameter to set
 */
int cio_enable_subchannel(struct subchannel *sch, u32 intparm)
{
        int ret;

        CIO_TRACE_EVENT(2, "ensch");
        CIO_TRACE_EVENT(2, dev_name(&sch->dev));

        if (sch_is_pseudo_sch(sch))
                return -EINVAL;
        if (cio_update_schib(sch))
                return -ENODEV;

        sch->config.ena = 1;
        sch->config.isc = sch->isc;
        sch->config.intparm = intparm;

        ret = cio_commit_config(sch);
        if (ret == -EIO) {
                /*
                 * Got a program check in msch. Try without
                 * the concurrent sense bit the next time.
                 */
                sch->config.csense = 0;
                ret = cio_commit_config(sch);
        }
        CIO_HEX_EVENT(2, &ret, sizeof(ret));
        return ret;
}
EXPORT_SYMBOL_GPL(cio_enable_subchannel);

/**
 * cio_disable_subchannel - disable a subchannel.
 * @sch: subchannel to disable
 */
int cio_disable_subchannel(struct subchannel *sch)
{
        int ret;

        CIO_TRACE_EVENT(2, "dissch");
        CIO_TRACE_EVENT(2, dev_name(&sch->dev));

        if (sch_is_pseudo_sch(sch))
                return 0;
        if (cio_update_schib(sch))
                return -ENODEV;

        sch->config.ena = 0;
        ret = cio_commit_config(sch);

        CIO_HEX_EVENT(2, &ret, sizeof(ret));
        return ret;
}
EXPORT_SYMBOL_GPL(cio_disable_subchannel);

static int cio_check_devno_blacklisted(struct subchannel *sch)
{
        if (is_blacklisted(sch->schid.ssid, sch->schib.pmcw.dev)) {
                /*
                 * This device must not be known to Linux. So we simply
                 * say that there is no device and return ENODEV.
                 */
                CIO_MSG_EVENT(6, "Blacklisted device detected "
                              "at devno %04X, subchannel set %x\n",
                              sch->schib.pmcw.dev, sch->schid.ssid);
                return -ENODEV;
        }
        return 0;
}

/**
 * cio_validate_subchannel - basic validation of subchannel
 * @sch: subchannel structure to be filled out
 * @schid: subchannel id
 *
 * Find out subchannel type and initialize struct subchannel.
 * Return codes:
 *   0 on success
 *   -ENXIO for non-defined subchannels
 *   -ENODEV for invalid subchannels or blacklisted devices
 *   -EIO for subchannels in an invalid subchannel set
 */
int cio_validate_subchannel(struct subchannel *sch, struct subchannel_id schid)
{
        char dbf_txt[15];
        int ccode;
        int err;

        sprintf(dbf_txt, "valsch%x", schid.sch_no);
        CIO_TRACE_EVENT(4, dbf_txt);

        /*
         * The first subchannel that is not-operational (ccode==3)
         * indicates that there aren't any more devices available.
         * If stsch gets an exception, it means the current subchannel set
         * is not valid.
         */
        ccode = stsch(schid, &sch->schib);
        if (ccode) {
                err = (ccode == 3) ? -ENXIO : ccode;
                goto out;
        }
        sch->st = sch->schib.pmcw.st;
        sch->schid = schid;

        switch (sch->st) {
        case SUBCHANNEL_TYPE_IO:
        case SUBCHANNEL_TYPE_MSG:
                if (!css_sch_is_valid(&sch->schib))
                        err = -ENODEV;
                else
                        err = cio_check_devno_blacklisted(sch);
                break;
        default:
                err = 0;
        }
        if (err)
                goto out;

        CIO_MSG_EVENT(4, "Subchannel 0.%x.%04x reports subchannel type %04X\n",
                      sch->schid.ssid, sch->schid.sch_no, sch->st);
out:
        return err;
}

/*
 * do_cio_interrupt() handles all normal I/O device IRQ's
 */
static irqreturn_t do_cio_interrupt(int irq, void *dummy)
{
        struct tpi_info *tpi_info;
        struct subchannel *sch;
        struct irb *irb;

        set_cpu_flag(CIF_NOHZ_DELAY);
        tpi_info = (struct tpi_info *) &get_irq_regs()->int_code;
        trace_s390_cio_interrupt(tpi_info);
        irb = this_cpu_ptr(&cio_irb);
        sch = (struct subchannel *)(unsigned long) tpi_info->intparm;
        if (!sch) {
                /* Clear pending interrupt condition. */
                inc_irq_stat(IRQIO_CIO);
                tsch(tpi_info->schid, irb);
                return IRQ_HANDLED;
        }
        spin_lock(sch->lock);
        /* Store interrupt response block to lowcore. */
        if (tsch(tpi_info->schid, irb) == 0) {
                /* Keep subchannel information word up to date. */
                memcpy (&sch->schib.scsw, &irb->scsw, sizeof (irb->scsw));
                /* Call interrupt handler if there is one. */
                if (sch->driver && sch->driver->irq)
                        sch->driver->irq(sch);
                else
                        inc_irq_stat(IRQIO_CIO);
        } else
                inc_irq_stat(IRQIO_CIO);
        spin_unlock(sch->lock);

        return IRQ_HANDLED;
}

static struct irqaction io_interrupt = {
        .name    = "IO",
        .handler = do_cio_interrupt,
};

void __init init_cio_interrupts(void)
{
        irq_set_chip_and_handler(IO_INTERRUPT,
                                 &dummy_irq_chip, handle_percpu_irq);
        setup_irq(IO_INTERRUPT, &io_interrupt);
}

#ifdef CONFIG_CCW_CONSOLE
static struct subchannel *console_sch;
static struct lock_class_key console_sch_key;

/*
 * Use cio_tsch to update the subchannel status and call the interrupt handler
 * if status had been pending. Called with the subchannel's lock held.
 */
void cio_tsch(struct subchannel *sch)
{
        struct irb *irb;
        int irq_context;

        irb = this_cpu_ptr(&cio_irb);
        /* Store interrupt response block to lowcore. */
        if (tsch(sch->schid, irb) != 0)
                /* Not status pending or not operational. */
                return;
        memcpy(&sch->schib.scsw, &irb->scsw, sizeof(union scsw));
        /* Call interrupt handler with updated status. */
        irq_context = in_interrupt();
        if (!irq_context) {
                local_bh_disable();
                irq_enter();
        }
        kstat_incr_irq_this_cpu(IO_INTERRUPT);
        if (sch->driver && sch->driver->irq)
                sch->driver->irq(sch);
        else
                inc_irq_stat(IRQIO_CIO);
        if (!irq_context) {
                irq_exit();
                _local_bh_enable();
        }
}

static int cio_test_for_console(struct subchannel_id schid, void *data)
{
        struct schib schib;

        if (stsch(schid, &schib) != 0)
                return -ENXIO;
        if ((schib.pmcw.st == SUBCHANNEL_TYPE_IO) && schib.pmcw.dnv &&
            (schib.pmcw.dev == console_devno)) {
                console_irq = schid.sch_no;
                return 1; /* found */
        }
        return 0;
}

static int cio_get_console_sch_no(void)
{
        struct subchannel_id schid;
        struct schib schib;

        init_subchannel_id(&schid);
        if (console_irq != -1) {
                /* VM provided us with the irq number of the console. */
                schid.sch_no = console_irq;
                if (stsch(schid, &schib) != 0 ||
                    (schib.pmcw.st != SUBCHANNEL_TYPE_IO) || !schib.pmcw.dnv)
                        return -1;
                console_devno = schib.pmcw.dev;
        } else if (console_devno != -1) {
                /* At least the console device number is known. */
                for_each_subchannel(cio_test_for_console, NULL);
        }
        return console_irq;
}

struct subchannel *cio_probe_console(void)
{
        struct subchannel_id schid;
        struct subchannel *sch;
        int sch_no, ret;

        sch_no = cio_get_console_sch_no();
        if (sch_no == -1) {
                pr_warn("No CCW console was found\n");
                return ERR_PTR(-ENODEV);
        }
        init_subchannel_id(&schid);
        schid.sch_no = sch_no;
        sch = css_alloc_subchannel(schid);
        if (IS_ERR(sch))
                return sch;

        lockdep_set_class(sch->lock, &console_sch_key);
        isc_register(CONSOLE_ISC);
        sch->config.isc = CONSOLE_ISC;
        sch->config.intparm = (u32)(addr_t)sch;
        ret = cio_commit_config(sch);
        if (ret) {
                isc_unregister(CONSOLE_ISC);
                put_device(&sch->dev);
                return ERR_PTR(ret);
        }
        console_sch = sch;
        return sch;
}

int cio_is_console(struct subchannel_id schid)
{
        if (!console_sch)
                return 0;
        return schid_equal(&schid, &console_sch->schid);
}

void cio_register_early_subchannels(void)
{
        int ret;

        if (!console_sch)
                return;

        ret = css_register_subchannel(console_sch);
        if (ret)
                put_device(&console_sch->dev);
}
#endif /* CONFIG_CCW_CONSOLE */

static int
__disable_subchannel_easy(struct subchannel_id schid, struct schib *schib)
{
        int retry, cc;

        cc = 0;
        for (retry=0;retry<3;retry++) {
                schib->pmcw.ena = 0;
                cc = msch(schid, schib);
                if (cc)
                        return (cc==3?-ENODEV:-EBUSY);
                if (stsch(schid, schib) || !css_sch_is_valid(schib))
                        return -ENODEV;
                if (!schib->pmcw.ena)
                        return 0;
        }
        return -EBUSY; /* uhm... */
}

static int
__clear_io_subchannel_easy(struct subchannel_id schid)
{
        int retry;

        if (csch(schid))
                return -ENODEV;
        for (retry=0;retry<20;retry++) {
                struct tpi_info ti;

                if (tpi(&ti)) {
                        tsch(ti.schid, this_cpu_ptr(&cio_irb));
                        if (schid_equal(&ti.schid, &schid))
                                return 0;
                }
                udelay_simple(100);
        }
        return -EBUSY;
}

static void __clear_chsc_subchannel_easy(void)
{
        /* It seems we can only wait for a bit here :/ */
        udelay_simple(100);
}

static int pgm_check_occured;

static void cio_reset_pgm_check_handler(void)
{
        pgm_check_occured = 1;
}

static int stsch_reset(struct subchannel_id schid, struct schib *addr)
{
        int rc;

        pgm_check_occured = 0;
        s390_base_pgm_handler_fn = cio_reset_pgm_check_handler;
        rc = stsch(schid, addr);
        s390_base_pgm_handler_fn = NULL;

        /* The program check handler could have changed pgm_check_occured. */
        barrier();

        if (pgm_check_occured)
                return -EIO;
        else
                return rc;
}

static int __shutdown_subchannel_easy(struct subchannel_id schid, void *data)
{
        struct schib schib;

        if (stsch_reset(schid, &schib))
                return -ENXIO;
        if (!schib.pmcw.ena)
                return 0;
        switch(__disable_subchannel_easy(schid, &schib)) {
        case 0:
        case -ENODEV:
                break;
        default: /* -EBUSY */
                switch (schib.pmcw.st) {
                case SUBCHANNEL_TYPE_IO:
                        if (__clear_io_subchannel_easy(schid))
                                goto out; /* give up... */
                        break;
                case SUBCHANNEL_TYPE_CHSC:
                        __clear_chsc_subchannel_easy();
                        break;
                default:
                        /* No default clear strategy */
                        break;
                }
                stsch(schid, &schib);
                __disable_subchannel_easy(schid, &schib);
        }
out:
        return 0;
}

static atomic_t chpid_reset_count;

static void s390_reset_chpids_mcck_handler(void)
{
        struct crw crw;
        union mci mci;

        /* Check for pending channel report word. */
        mci.val = S390_lowcore.mcck_interruption_code;
        if (!mci.cp)
                return;
        /* Process channel report words. */
        while (stcrw(&crw) == 0) {
                /* Check for responses to RCHP. */
                if (crw.slct && crw.rsc == CRW_RSC_CPATH)
                        atomic_dec(&chpid_reset_count);
        }
}

#define RCHP_TIMEOUT (30 * USEC_PER_SEC)
static void css_reset(void)
{
        int i, ret;
        unsigned long long timeout;
        struct chp_id chpid;

        /* Reset subchannels. */
        for_each_subchannel(__shutdown_subchannel_easy,  NULL);
        /* Reset channel paths. */
        s390_base_mcck_handler_fn = s390_reset_chpids_mcck_handler;
        /* Enable channel report machine checks. */
        __ctl_set_bit(14, 28);
        /* Temporarily reenable machine checks. */
        local_mcck_enable();
        chp_id_init(&chpid);
        for (i = 0; i <= __MAX_CHPID; i++) {
                chpid.id = i;
                ret = rchp(chpid);
                if ((ret == 0) || (ret == 2))
                        /*
                         * rchp either succeeded, or another rchp is already
                         * in progress. In either case, we'll get a crw.
                         */
                        atomic_inc(&chpid_reset_count);
        }
        /* Wait for machine check for all channel paths. */
        timeout = get_tod_clock_fast() + (RCHP_TIMEOUT << 12);
        while (atomic_read(&chpid_reset_count) != 0) {
                if (get_tod_clock_fast() > timeout)
                        break;
                cpu_relax();
        }
        /* Disable machine checks again. */
        local_mcck_disable();
        /* Disable channel report machine checks. */
        __ctl_clear_bit(14, 28);
        s390_base_mcck_handler_fn = NULL;
}

static struct reset_call css_reset_call = {
        .fn = css_reset,
};

static int __init init_css_reset_call(void)
{
        atomic_set(&chpid_reset_count, 0);
        register_reset_call(&css_reset_call);
        return 0;
}

arch_initcall(init_css_reset_call);

struct sch_match_id {
        struct subchannel_id schid;
        struct ccw_dev_id devid;
        int rc;
};

static int __reipl_subchannel_match(struct subchannel_id schid, void *data)
{
        struct schib schib;
        struct sch_match_id *match_id = data;

        if (stsch_reset(schid, &schib))
                return -ENXIO;
        if ((schib.pmcw.st == SUBCHANNEL_TYPE_IO) && schib.pmcw.dnv &&
            (schib.pmcw.dev == match_id->devid.devno) &&
            (schid.ssid == match_id->devid.ssid)) {
                match_id->schid = schid;
                match_id->rc = 0;
                return 1;
        }
        return 0;
}

static int reipl_find_schid(struct ccw_dev_id *devid,
                            struct subchannel_id *schid)
{
        struct sch_match_id match_id;

        match_id.devid = *devid;
        match_id.rc = -ENODEV;
        for_each_subchannel(__reipl_subchannel_match, &match_id);
        if (match_id.rc == 0)
                *schid = match_id.schid;
        return match_id.rc;
}

extern void do_reipl_asm(__u32 schid);

/* Make sure all subchannels are quiet before we re-ipl an lpar. */
void reipl_ccw_dev(struct ccw_dev_id *devid)
{
        struct subchannel_id uninitialized_var(schid);

        s390_reset_system();
        if (reipl_find_schid(devid, &schid) != 0)
                panic("IPL Device not found\n");
        do_reipl_asm(*((__u32*)&schid));
}

int __init cio_get_iplinfo(struct cio_iplinfo *iplinfo)
{
        static struct chsc_sda_area sda_area __initdata;
        struct subchannel_id schid;
        struct schib schib;

        schid = *(struct subchannel_id *)&S390_lowcore.subchannel_id;
        if (!schid.one)
                return -ENODEV;

        if (schid.ssid) {
                /*
                 * Firmware should have already enabled MSS but whoever started
                 * the kernel might have initiated a channel subsystem reset.
                 * Ensure that MSS is enabled.
                 */
                memset(&sda_area, 0, sizeof(sda_area));
                if (__chsc_enable_facility(&sda_area, CHSC_SDA_OC_MSS))
                        return -ENODEV;
        }
        if (stsch(schid, &schib))
                return -ENODEV;
        if (schib.pmcw.st != SUBCHANNEL_TYPE_IO)
                return -ENODEV;
        if (!schib.pmcw.dnv)
                return -ENODEV;

        iplinfo->ssid = schid.ssid;
        iplinfo->devno = schib.pmcw.dev;
        iplinfo->is_qdio = schib.pmcw.qf;
        return 0;
}

/**
 * cio_tm_start_key - perform start function
 * @sch: subchannel on which to perform the start function
 * @tcw: transport-command word to be started
 * @lpm: mask of paths to use
 * @key: storage key to use for storage access
 *
 * Start the tcw on the given subchannel. Return zero on success, non-zero
 * otherwise.
 */
int cio_tm_start_key(struct subchannel *sch, struct tcw *tcw, u8 lpm, u8 key)
{
        int cc;
        union orb *orb = &to_io_private(sch)->orb;

        memset(orb, 0, sizeof(union orb));
        orb->tm.intparm = (u32) (addr_t) sch;
        orb->tm.key = key >> 4;
        orb->tm.b = 1;
        orb->tm.lpm = lpm ? lpm : sch->lpm;
        orb->tm.tcw = (u32) (addr_t) tcw;
        cc = ssch(sch->schid, orb);
        switch (cc) {
        case 0:
                return 0;
        case 1:
        case 2:
                return -EBUSY;
        default:
                return cio_start_handle_notoper(sch, lpm);
        }
}
EXPORT_SYMBOL_GPL(cio_tm_start_key);

/**
 * cio_tm_intrg - perform interrogate function
 * @sch - subchannel on which to perform the interrogate function
 *
 * If the specified subchannel is running in transport-mode, perform the
 * interrogate function. Return zero on success, non-zero otherwie.
 */
int cio_tm_intrg(struct subchannel *sch)
{
        int cc;

        if (!to_io_private(sch)->orb.tm.b)
                return -EINVAL;
        cc = xsch(sch->schid);
        switch (cc) {
        case 0:
        case 2:
                return 0;
        case 1:
                return -EBUSY;
        default:
                return -ENODEV;
        }
}
EXPORT_SYMBOL_GPL(cio_tm_intrg);