/*
 *  drivers/s390/cio/cio.c
 *   S/390 common I/O routines -- low level i/o calls
 *
 *    Copyright (C) IBM Corp. 1999,2006
 *    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)
 */

#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 <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 "airq.h"
#include "cio.h"
#include "css.h"
#include "chsc.h"
#include "ioasm.h"
#include "blacklist.h"
#include "cio_debug.h"
#include "chp.h"
#include "../s390mach.h"

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

int cio_show_msg;

static int __init
cio_setup (char *parm)
{
        if (!strcmp (parm, "yes"))
                cio_show_msg = 1;
        else if (!strcmp (parm, "no"))
                cio_show_msg = 0;
        else
                printk(KERN_ERR "cio: cio_setup: "
                       "invalid cio_msg parameter '%s'", parm);
        return 1;
}

__setup ("cio_msg=", cio_setup);

/*
 * Function: cio_debug_init
 * Initializes three debug logs (under /proc/s390dbf) for common I/O:
 * - cio_msg logs the messages which are printk'ed when CONFIG_DEBUG_IO is on
 * - cio_trace logs the calling of different functions
 * - cio_crw logs the messages which are printk'ed when CONFIG_DEBUG_CRW is on
 * debug levels depend on CONFIG_DEBUG_IO resp. CONFIG_DEBUG_CRW
 */
static int __init
cio_debug_init (void)
{
        cio_debug_msg_id = debug_register ("cio_msg", 16, 4, 16*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, 4, 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", 4, 4, 16*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, 2);
        return 0;

out_unregister:
        if (cio_debug_msg_id)
                debug_unregister (cio_debug_msg_id);
        if (cio_debug_trace_id)
                debug_unregister (cio_debug_trace_id);
        if (cio_debug_crw_id)
                debug_unregister (cio_debug_crw_id);
        printk(KERN_WARNING"cio: could not initialize debugging\n");
        return -1;
}

arch_initcall (cio_debug_init);

int
cio_set_options (struct subchannel *sch, int flags)
{
       sch->options.suspend = (flags & DOIO_ALLOW_SUSPEND) != 0;
       sch->options.prefetch = (flags & DOIO_DENY_PREFETCH) != 0;
       sch->options.inter = (flags & DOIO_SUPPRESS_INTER) != 0;
       return 0;
}

/* FIXME: who wants to use this? */
int
cio_get_options (struct subchannel *sch)
{
       int flags;

       flags = 0;
       if (sch->options.suspend)
                flags |= DOIO_ALLOW_SUSPEND;
       if (sch->options.prefetch)
                flags |= DOIO_DENY_PREFETCH;
       if (sch->options.inter)
                flags |= DOIO_SUPPRESS_INTER;
       return flags;
}

/*
 * Use tpi to get a pending interrupt, call the interrupt handler and
 * return a pointer to the subchannel structure.
 */
static int
cio_tpi(void)
{
        struct tpi_info *tpi_info;
        struct subchannel *sch;
        struct irb *irb;

        tpi_info = (struct tpi_info *) __LC_SUBCHANNEL_ID;
        if (tpi (NULL) != 1)
                return 0;
        irb = (struct irb *) __LC_IRB;
        /* Store interrupt response block to lowcore. */
        if (tsch (tpi_info->schid, irb) != 0)
                /* Not status pending or not operational. */
                return 1;
        sch = (struct subchannel *)(unsigned long)tpi_info->intparm;
        if (!sch)
                return 1;
        local_bh_disable();
        irq_enter ();
        spin_lock(sch->lock);
        memcpy (&sch->schib.scsw, &irb->scsw, sizeof (struct scsw));
        if (sch->driver && sch->driver->irq)
                sch->driver->irq(&sch->dev);
        spin_unlock(sch->lock);
        irq_exit ();
        _local_bh_enable();
        return 1;
}

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;

        stsch (sch->schid, &sch->schib);

        CIO_MSG_EVENT(0, "cio_start: 'not oper' status for "
                      "subchannel 0.%x.%04x!\n", sch->schid.ssid,
                      sch->schid.sch_no);
        sprintf(dbf_text, "no%s", sch->dev.bus_id);
        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 */
{
        char dbf_txt[15];
        int ccode;

        CIO_TRACE_EVENT (4, "stIO");
        CIO_TRACE_EVENT (4, sch->dev.bus_id);

        /* sch is always under 2G. */
        sch->orb.intparm = (__u32)(unsigned long)sch;
        sch->orb.fmt = 1;

        sch->orb.pfch = sch->options.prefetch == 0;
        sch->orb.spnd = sch->options.suspend;
        sch->orb.ssic = sch->options.suspend && sch->options.inter;
        sch->orb.lpm = (lpm != 0) ? lpm : sch->lpm;
#ifdef CONFIG_64BIT
        /*
         * for 64 bit we always support 64 bit IDAWs with 4k page size only
         */
        sch->orb.c64 = 1;
        sch->orb.i2k = 0;
#endif
        sch->orb.key = key >> 4;
        /* issue "Start Subchannel" */
        sch->orb.cpa = (__u32) __pa (cpa);
        ccode = ssch (sch->schid, &sch->orb);

        /* process condition code */
        sprintf (dbf_txt, "ccode:%d", ccode);
        CIO_TRACE_EVENT (4, dbf_txt);

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

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

/*
 * resume suspended I/O operation
 */
int
cio_resume (struct subchannel *sch)
{
        char dbf_txt[15];
        int ccode;

        CIO_TRACE_EVENT (4, "resIO");
        CIO_TRACE_EVENT (4, sch->dev.bus_id);

        ccode = rsch (sch->schid);

        sprintf (dbf_txt, "ccode:%d", ccode);
        CIO_TRACE_EVENT (4, dbf_txt);

        switch (ccode) {
        case 0:
                sch->schib.scsw.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;
        }
}

/*
 * halt I/O operation
 */
int
cio_halt(struct subchannel *sch)
{
        char dbf_txt[15];
        int ccode;

        if (!sch)
                return -ENODEV;

        CIO_TRACE_EVENT (2, "haltIO");
        CIO_TRACE_EVENT (2, sch->dev.bus_id);

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

        sprintf (dbf_txt, "ccode:%d", ccode);
        CIO_TRACE_EVENT (2, dbf_txt);

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

/*
 * Clear I/O operation
 */
int
cio_clear(struct subchannel *sch)
{
        char dbf_txt[15];
        int ccode;

        if (!sch)
                return -ENODEV;

        CIO_TRACE_EVENT (2, "clearIO");
        CIO_TRACE_EVENT (2, sch->dev.bus_id);

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

        sprintf (dbf_txt, "ccode:%d", ccode);
        CIO_TRACE_EVENT (2, dbf_txt);

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

/*
 * 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)
{
        char dbf_txt[15];
        int ccode;

        if (!sch)
                return -ENODEV;

        CIO_TRACE_EVENT (2, "cancelIO");
        CIO_TRACE_EVENT (2, sch->dev.bus_id);

        ccode = xsch (sch->schid);

        sprintf (dbf_txt, "ccode:%d", ccode);
        CIO_TRACE_EVENT (2, dbf_txt);

        switch (ccode) {
        case 0:         /* success */
                /* Update information in scsw. */
                stsch (sch->schid, &sch->schib);
                return 0;
        case 1:         /* status pending */
                return -EBUSY;
        case 2:         /* not applicable */
                return -EINVAL;
        default:        /* not oper */
                return -ENODEV;
        }
}

/*
 * Function: cio_modify
 * Issues a "Modify Subchannel" on the specified subchannel
 */
int
cio_modify (struct subchannel *sch)
{
        int ccode, retry, ret;

        ret = 0;
        for (retry = 0; retry < 5; retry++) {
                ccode = msch_err (sch->schid, &sch->schib);
                if (ccode < 0)  /* -EIO if msch gets a program check. */
                        return ccode;
                switch (ccode) {
                case 0: /* successfull */
                        return 0;
                case 1: /* status pending */
                        return -EBUSY;
                case 2: /* busy */
                        udelay (100);   /* allow for recovery */
                        ret = -EBUSY;
                        break;
                case 3: /* not operational */
                        return -ENODEV;
                }
        }
        return ret;
}

/*
 * Enable subchannel.
 */
int
cio_enable_subchannel (struct subchannel *sch, unsigned int isc)
{
        char dbf_txt[15];
        int ccode;
        int retry;
        int ret;

        CIO_TRACE_EVENT (2, "ensch");
        CIO_TRACE_EVENT (2, sch->dev.bus_id);

        if (sch_is_pseudo_sch(sch))
                return -EINVAL;
        ccode = stsch (sch->schid, &sch->schib);
        if (ccode)
                return -ENODEV;

        for (retry = 5, ret = 0; retry > 0; retry--) {
                sch->schib.pmcw.ena = 1;
                sch->schib.pmcw.isc = isc;
                sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
                ret = cio_modify(sch);
                if (ret == -ENODEV)
                        break;
                if (ret == -EIO)
                        /*
                         * Got a program check in cio_modify. Try without
                         * the concurrent sense bit the next time.
                         */
                        sch->schib.pmcw.csense = 0;
                if (ret == 0) {
                        stsch (sch->schid, &sch->schib);
                        if (sch->schib.pmcw.ena)
                                break;
                }
                if (ret == -EBUSY) {
                        struct irb irb;
                        if (tsch(sch->schid, &irb) != 0)
                                break;
                }
        }
        sprintf (dbf_txt, "ret:%d", ret);
        CIO_TRACE_EVENT (2, dbf_txt);
        return ret;
}

/*
 * Disable subchannel.
 */
int
cio_disable_subchannel (struct subchannel *sch)
{
        char dbf_txt[15];
        int ccode;
        int retry;
        int ret;

        CIO_TRACE_EVENT (2, "dissch");
        CIO_TRACE_EVENT (2, sch->dev.bus_id);

        if (sch_is_pseudo_sch(sch))
                return 0;
        ccode = stsch (sch->schid, &sch->schib);
        if (ccode == 3)         /* Not operational. */
                return -ENODEV;

        if (sch->schib.scsw.actl != 0)
                /*
                 * the disable function must not be called while there are
                 *  requests pending for completion !
                 */
                return -EBUSY;

        for (retry = 5, ret = 0; retry > 0; retry--) {
                sch->schib.pmcw.ena = 0;
                ret = cio_modify(sch);
                if (ret == -ENODEV)
                        break;
                if (ret == -EBUSY)
                        /*
                         * The subchannel is busy or status pending.
                         * We'll disable when the next interrupt was delivered
                         * via the state machine.
                         */
                        break;
                if (ret == 0) {
                        stsch (sch->schid, &sch->schib);
                        if (!sch->schib.pmcw.ena)
                                break;
                }
        }
        sprintf (dbf_txt, "ret:%d", ret);
        CIO_TRACE_EVENT (2, dbf_txt);
        return ret;
}

int cio_create_sch_lock(struct subchannel *sch)
{
        sch->lock = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
        if (!sch->lock)
                return -ENOMEM;
        spin_lock_init(sch->lock);
        return 0;
}

/*
 * cio_validate_subchannel()
 *
 * Find out subchannel type and initialize struct subchannel.
 * Return codes:
 *   SUBCHANNEL_TYPE_IO for a normal io subchannel
 *   SUBCHANNEL_TYPE_CHSC for a chsc subchannel
 *   SUBCHANNEL_TYPE_MESSAGE for a messaging subchannel
 *   SUBCHANNEL_TYPE_ADM for a adm(?) subchannel
 *   -ENXIO for non-defined subchannels
 *   -ENODEV for subchannels with invalid device number or blacklisted devices
 */
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);

        /* Nuke all fields. */
        memset(sch, 0, sizeof(struct subchannel));

        sch->schid = schid;
        if (cio_is_console(schid)) {
                sch->lock = cio_get_console_lock();
        } else {
                err = cio_create_sch_lock(sch);
                if (err)
                        goto out;
        }
        mutex_init(&sch->reg_mutex);
        /* Set a name for the subchannel */
        snprintf (sch->dev.bus_id, BUS_ID_SIZE, "0.%x.%04x", schid.ssid,
                  schid.sch_no);

        /*
         * 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_err (schid, &sch->schib);
        if (ccode) {
                err = (ccode == 3) ? -ENXIO : ccode;
                goto out;
        }
        /* Copy subchannel type from path management control word. */
        sch->st = sch->schib.pmcw.st;

        /*
         * ... just being curious we check for non I/O subchannels
         */
        if (sch->st != 0) {
                CIO_DEBUG(KERN_INFO, 0,
                          "cio: Subchannel 0.%x.%04x reports "
                          "non-I/O subchannel type %04X\n",
                          sch->schid.ssid, sch->schid.sch_no, sch->st);
                /* We stop here for non-io subchannels. */
                err = sch->st;
                goto out;
        }

        /* Initialization for io subchannels. */
        if (!sch->schib.pmcw.dnv) {
                /* io subchannel but device number is invalid. */
                err = -ENODEV;
                goto out;
        }
        /* Devno is valid. */
        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(4, "Blacklisted device detected "
                              "at devno %04X, subchannel set %x\n",
                              sch->schib.pmcw.dev, sch->schid.ssid);
                err = -ENODEV;
                goto out;
        }
        if (cio_is_console(sch->schid))
                sch->opm = 0xff;
        else
                sch->opm = chp_get_sch_opm(sch);
        sch->lpm = sch->schib.pmcw.pam & sch->opm;

        CIO_DEBUG(KERN_INFO, 0,
                  "cio: Detected device %04x on subchannel 0.%x.%04X"
                  " - PIM = %02X, PAM = %02X, POM = %02X\n",
                  sch->schib.pmcw.dev, sch->schid.ssid,
                  sch->schid.sch_no, sch->schib.pmcw.pim,
                  sch->schib.pmcw.pam, sch->schib.pmcw.pom);

        /*
         * We now have to initially ...
         *  ... set "interruption subclass"
         *  ... enable "concurrent sense"
         *  ... enable "multipath mode" if more than one
         *        CHPID is available. This is done regardless
         *        whether multiple paths are available for us.
         */
        sch->schib.pmcw.isc = 3;        /* could be smth. else */
        sch->schib.pmcw.csense = 1;     /* concurrent sense */
        sch->schib.pmcw.ena = 0;
        if ((sch->lpm & (sch->lpm - 1)) != 0)
                sch->schib.pmcw.mp = 1; /* multipath mode */
        /* clean up possible residual cmf stuff */
        sch->schib.pmcw.mme = 0;
        sch->schib.pmcw.mbfc = 0;
        sch->schib.pmcw.mbi = 0;
        sch->schib.mba = 0;
        return 0;
out:
        if (!cio_is_console(schid))
                kfree(sch->lock);
        sch->lock = NULL;
        return err;
}

/*
 * do_IRQ() handles all normal I/O device IRQ's (the special
 *          SMP cross-CPU interrupts have their own specific
 *          handlers).
 *
 */
void
do_IRQ (struct pt_regs *regs)
{
        struct tpi_info *tpi_info;
        struct subchannel *sch;
        struct irb *irb;
        struct pt_regs *old_regs;

        old_regs = set_irq_regs(regs);
        irq_enter();
        asm volatile ("mc 0,0");
        if (S390_lowcore.int_clock >= S390_lowcore.jiffy_timer)
                /**
                 * Make sure that the i/o interrupt did not "overtake"
                 * the last HZ timer interrupt.
                 */
                account_ticks(S390_lowcore.int_clock);
        /*
         * Get interrupt information from lowcore
         */
        tpi_info = (struct tpi_info *) __LC_SUBCHANNEL_ID;
        irb = (struct irb *) __LC_IRB;
        do {
                kstat_cpu(smp_processor_id()).irqs[IO_INTERRUPT]++;
                /*
                 * Non I/O-subchannel thin interrupts are processed differently
                 */
                if (tpi_info->adapter_IO == 1 &&
                    tpi_info->int_type == IO_INTERRUPT_TYPE) {
                        do_adapter_IO();
                        continue;
                }
                sch = (struct subchannel *)(unsigned long)tpi_info->intparm;
                if (sch)
                        spin_lock(sch->lock);
                /* Store interrupt response block to lowcore. */
                if (tsch (tpi_info->schid, irb) == 0 && sch) {
                        /* 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->dev);
                }
                if (sch)
                        spin_unlock(sch->lock);
                /*
                 * Are more interrupts pending?
                 * If so, the tpi instruction will update the lowcore
                 * to hold the info for the next interrupt.
                 * We don't do this for VM because a tpi drops the cpu
                 * out of the sie which costs more cycles than it saves.
                 */
        } while (!MACHINE_IS_VM && tpi (NULL) != 0);
        irq_exit();
        set_irq_regs(old_regs);
}

#ifdef CONFIG_CCW_CONSOLE
static struct subchannel console_subchannel;
static int console_subchannel_in_use;

/*
 * busy wait for the next interrupt on the console
 */
void
wait_cons_dev (void)
{
        unsigned long cr6      __attribute__ ((aligned (8)));
        unsigned long save_cr6 __attribute__ ((aligned (8)));

        /* 
         * before entering the spinlock we may already have
         * processed the interrupt on a different CPU...
         */
        if (!console_subchannel_in_use)
                return;

        /* disable all but isc 7 (console device) */
        __ctl_store (save_cr6, 6, 6);
        cr6 = 0x01000000;
        __ctl_load (cr6, 6, 6);

        do {
                spin_unlock(console_subchannel.lock);
                if (!cio_tpi())
                        cpu_relax();
                spin_lock(console_subchannel.lock);
        } while (console_subchannel.schib.scsw.actl != 0);
        /*
         * restore previous isc value
         */
        __ctl_load (save_cr6, 6, 6);
}

static int
cio_test_for_console(struct subchannel_id schid, void *data)
{
        if (stsch_err(schid, &console_subchannel.schib) != 0)
                return -ENXIO;
        if (console_subchannel.schib.pmcw.dnv &&
            console_subchannel.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;
        
        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, &console_subchannel.schib) != 0 ||
                    !console_subchannel.schib.pmcw.dnv)
                        return -1;
                console_devno = console_subchannel.schib.pmcw.dev;
        } else if (console_devno != -1) {
                /* At least the console device number is known. */
                for_each_subchannel(cio_test_for_console, NULL);
                if (console_irq == -1)
                        return -1;
        } else {
                /* unlike in 2.4, we cannot autoprobe here, since
                 * the channel subsystem is not fully initialized.
                 * With some luck, the HWC console can take over */
                printk(KERN_WARNING "cio: No ccw console found!\n");
                return -1;
        }
        return console_irq;
}

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

        if (xchg(&console_subchannel_in_use, 1) != 0)
                return ERR_PTR(-EBUSY);
        sch_no = cio_get_console_sch_no();
        if (sch_no == -1) {
                console_subchannel_in_use = 0;
                return ERR_PTR(-ENODEV);
        }
        memset(&console_subchannel, 0, sizeof(struct subchannel));
        init_subchannel_id(&schid);
        schid.sch_no = sch_no;
        ret = cio_validate_subchannel(&console_subchannel, schid);
        if (ret) {
                console_subchannel_in_use = 0;
                return ERR_PTR(-ENODEV);
        }

        /*
         * enable console I/O-interrupt subclass 7
         */
        ctl_set_bit(6, 24);
        console_subchannel.schib.pmcw.isc = 7;
        console_subchannel.schib.pmcw.intparm =
                (__u32)(unsigned long)&console_subchannel;
        ret = cio_modify(&console_subchannel);
        if (ret) {
                console_subchannel_in_use = 0;
                return ERR_PTR(ret);
        }
        return &console_subchannel;
}

void
cio_release_console(void)
{
        console_subchannel.schib.pmcw.intparm = 0;
        cio_modify(&console_subchannel);
        ctl_clear_bit(6, 24);
        console_subchannel_in_use = 0;
}

/* Bah... hack to catch console special sausages. */
int
cio_is_console(struct subchannel_id schid)
{
        if (!console_subchannel_in_use)
                return 0;
        return schid_equal(&schid, &console_subchannel.schid);
}

struct subchannel *
cio_get_console_subchannel(void)
{
        if (!console_subchannel_in_use)
                return NULL;
        return &console_subchannel;
}

#endif
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);
                stsch(schid, schib);
                if (!schib->pmcw.ena)
                        return 0;
        }
        return -EBUSY; /* uhm... */
}

/* we can't use the normal udelay here, since it enables external interrupts */

static void udelay_reset(unsigned long usecs)
{
        uint64_t start_cc, end_cc;

        asm volatile ("STCK %0" : "=m" (start_cc));
        do {
                cpu_relax();
                asm volatile ("STCK %0" : "=m" (end_cc));
        } while (((end_cc - start_cc)/4096) < usecs);
}

static int
__clear_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, (struct irb *)__LC_IRB);
                        if (schid_equal(&ti.schid, &schid))
                                return 0;
                }
                udelay_reset(100);
        }
        return -EBUSY;
}

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, volatile 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 */
                if (__clear_subchannel_easy(schid))
                        break; /* give up... */
                stsch(schid, &schib);
                __disable_subchannel_easy(schid, &schib);
        }
        return 0;
}

static atomic_t chpid_reset_count;

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

        /* Check for pending channel report word. */
        mci = (struct mci *)&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_clock() + (RCHP_TIMEOUT << 12);
        while (atomic_read(&chpid_reset_count) != 0) {
                if (get_clock() > 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.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 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)
{
        struct subchannel_id schid;
        struct schib schib;

        schid = *(struct subchannel_id *)__LC_SUBCHANNEL_ID;
        if (!schid.one)
                return -ENODEV;
        if (stsch(schid, &schib))
                return -ENODEV;
        if (!schib.pmcw.dnv)
                return -ENODEV;
        iplinfo->devno = schib.pmcw.dev;
        iplinfo->is_qdio = schib.pmcw.qf;
        return 0;
}