/*
 * Copyright (C) 2001 Mike Corrigan  IBM Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/bootmem.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/module.h>

#include <asm/system.h>
#include <asm/paca.h>
#include <asm/firmware.h>
#include <asm/iseries/it_lp_queue.h>
#include <asm/iseries/hv_lp_event.h>
#include <asm/iseries/hv_call_event.h>
#include "it_lp_naca.h"

/*
 * The LpQueue is used to pass event data from the hypervisor to
 * the partition.  This is where I/O interrupt events are communicated.
 *
 * It is written to by the hypervisor so cannot end up in the BSS.
 */
struct hvlpevent_queue hvlpevent_queue __attribute__((__section__(".data")));

DEFINE_PER_CPU(unsigned long[HvLpEvent_Type_NumTypes], hvlpevent_counts);

static char *event_types[HvLpEvent_Type_NumTypes] = {
        "Hypervisor",
        "Machine Facilities",
        "Session Manager",
        "SPD I/O",
        "Virtual Bus",
        "PCI I/O",
        "RIO I/O",
        "Virtual Lan",
        "Virtual I/O"
};

/* Array of LpEvent handler functions */
static LpEventHandler lpEventHandler[HvLpEvent_Type_NumTypes];
static unsigned lpEventHandlerPaths[HvLpEvent_Type_NumTypes];

static struct HvLpEvent * get_next_hvlpevent(void)
{
        struct HvLpEvent * event;
        event = (struct HvLpEvent *)hvlpevent_queue.hq_current_event;

        if (hvlpevent_is_valid(event)) {
                /* rmb() needed only for weakly consistent machines (regatta) */
                rmb();
                /* Set pointer to next potential event */
                hvlpevent_queue.hq_current_event += ((event->xSizeMinus1 +
                                IT_LP_EVENT_ALIGN) / IT_LP_EVENT_ALIGN) *
                                        IT_LP_EVENT_ALIGN;

                /* Wrap to beginning if no room at end */
                if (hvlpevent_queue.hq_current_event >
                                hvlpevent_queue.hq_last_event) {
                        hvlpevent_queue.hq_current_event =
                                hvlpevent_queue.hq_event_stack;
                }
        } else {
                event = NULL;
        }

        return event;
}

static unsigned long spread_lpevents = NR_CPUS;

int hvlpevent_is_pending(void)
{
        struct HvLpEvent *next_event;

        if (smp_processor_id() >= spread_lpevents)
                return 0;

        next_event = (struct HvLpEvent *)hvlpevent_queue.hq_current_event;

        return hvlpevent_is_valid(next_event) ||
                hvlpevent_queue.hq_overflow_pending;
}

static void hvlpevent_clear_valid(struct HvLpEvent * event)
{
        /* Tell the Hypervisor that we're done with this event.
         * Also clear bits within this event that might look like valid bits.
         * ie. on 64-byte boundaries.
         */
        struct HvLpEvent *tmp;
        unsigned extra = ((event->xSizeMinus1 + IT_LP_EVENT_ALIGN) /
                                IT_LP_EVENT_ALIGN) - 1;

        switch (extra) {
        case 3:
                tmp = (struct HvLpEvent*)((char*)event + 3 * IT_LP_EVENT_ALIGN);
                hvlpevent_invalidate(tmp);
        case 2:
                tmp = (struct HvLpEvent*)((char*)event + 2 * IT_LP_EVENT_ALIGN);
                hvlpevent_invalidate(tmp);
        case 1:
                tmp = (struct HvLpEvent*)((char*)event + 1 * IT_LP_EVENT_ALIGN);
                hvlpevent_invalidate(tmp);
        }

        mb();

        hvlpevent_invalidate(event);
}

void process_hvlpevents(void)
{
        struct HvLpEvent * event;

 restart:
        /* If we have recursed, just return */
        if (!spin_trylock(&hvlpevent_queue.hq_lock))
                return;

        for (;;) {
                event = get_next_hvlpevent();
                if (event) {
                        /* Call appropriate handler here, passing
                         * a pointer to the LpEvent.  The handler
                         * must make a copy of the LpEvent if it
                         * needs it in a bottom half. (perhaps for
                         * an ACK)
                         *
                         *  Handlers are responsible for ACK processing
                         *
                         * The Hypervisor guarantees that LpEvents will
                         * only be delivered with types that we have
                         * registered for, so no type check is necessary
                         * here!
                         */
                        if (event->xType < HvLpEvent_Type_NumTypes)
                                __get_cpu_var(hvlpevent_counts)[event->xType]++;
                        if (event->xType < HvLpEvent_Type_NumTypes &&
                                        lpEventHandler[event->xType])
                                lpEventHandler[event->xType](event);
                        else {
                                u8 type = event->xType;

                                /*
                                 * Don't printk in the spinlock as printk
                                 * may require ack events form the HV to send
                                 * any characters there.
                                 */
                                hvlpevent_clear_valid(event);
                                spin_unlock(&hvlpevent_queue.hq_lock);
                                printk(KERN_INFO
                                        "Unexpected Lp Event type=%d\n", type);
                                goto restart;
                        }

                        hvlpevent_clear_valid(event);
                } else if (hvlpevent_queue.hq_overflow_pending)
                        /*
                         * No more valid events. If overflow events are
                         * pending process them
                         */
                        HvCallEvent_getOverflowLpEvents(hvlpevent_queue.hq_index);
                else
                        break;
        }

        spin_unlock(&hvlpevent_queue.hq_lock);
}

static int set_spread_lpevents(char *str)
{
        unsigned long val = simple_strtoul(str, NULL, 0);

        /*
         * The parameter is the number of processors to share in processing
         * lp events.
         */
        if (( val > 0) && (val <= NR_CPUS)) {
                spread_lpevents = val;
                printk("lpevent processing spread over %ld processors\n", val);
        } else {
                printk("invalid spread_lpevents %ld\n", val);
        }

        return 1;
}
__setup("spread_lpevents=", set_spread_lpevents);

void __init setup_hvlpevent_queue(void)
{
        void *eventStack;

        spin_lock_init(&hvlpevent_queue.hq_lock);

        /* Allocate a page for the Event Stack. */
        eventStack = alloc_bootmem_pages(IT_LP_EVENT_STACK_SIZE);
        memset(eventStack, 0, IT_LP_EVENT_STACK_SIZE);

        /* Invoke the hypervisor to initialize the event stack */
        HvCallEvent_setLpEventStack(0, eventStack, IT_LP_EVENT_STACK_SIZE);

        hvlpevent_queue.hq_event_stack = eventStack;
        hvlpevent_queue.hq_current_event = eventStack;
        hvlpevent_queue.hq_last_event = (char *)eventStack +
                (IT_LP_EVENT_STACK_SIZE - IT_LP_EVENT_MAX_SIZE);
        hvlpevent_queue.hq_index = 0;
}

/* Register a handler for an LpEvent type */
int HvLpEvent_registerHandler(HvLpEvent_Type eventType, LpEventHandler handler)
{
        if (eventType < HvLpEvent_Type_NumTypes) {
                lpEventHandler[eventType] = handler;
                return 0;
        }
        return 1;
}
EXPORT_SYMBOL(HvLpEvent_registerHandler);

int HvLpEvent_unregisterHandler(HvLpEvent_Type eventType)
{
        might_sleep();

        if (eventType < HvLpEvent_Type_NumTypes) {
                if (!lpEventHandlerPaths[eventType]) {
                        lpEventHandler[eventType] = NULL;
                        /*
                         * We now sleep until all other CPUs have scheduled.
                         * This ensures that the deletion is seen by all
                         * other CPUs, and that the deleted handler isn't
                         * still running on another CPU when we return.
                         */
                        synchronize_sched();
                        return 0;
                }
        }
        return 1;
}
EXPORT_SYMBOL(HvLpEvent_unregisterHandler);

/*
 * lpIndex is the partition index of the target partition.
 * needed only for VirtualIo, VirtualLan and SessionMgr.  Zero
 * indicates to use our partition index - for the other types.
 */
int HvLpEvent_openPath(HvLpEvent_Type eventType, HvLpIndex lpIndex)
{
        if ((eventType < HvLpEvent_Type_NumTypes) &&
                        lpEventHandler[eventType]) {
                if (lpIndex == 0)
                        lpIndex = itLpNaca.xLpIndex;
                HvCallEvent_openLpEventPath(lpIndex, eventType);
                ++lpEventHandlerPaths[eventType];
                return 0;
        }
        return 1;
}

int HvLpEvent_closePath(HvLpEvent_Type eventType, HvLpIndex lpIndex)
{
        if ((eventType < HvLpEvent_Type_NumTypes) &&
                        lpEventHandler[eventType] &&
                        lpEventHandlerPaths[eventType]) {
                if (lpIndex == 0)
                        lpIndex = itLpNaca.xLpIndex;
                HvCallEvent_closeLpEventPath(lpIndex, eventType);
                --lpEventHandlerPaths[eventType];
                return 0;
        }
        return 1;
}

static int proc_lpevents_show(struct seq_file *m, void *v)
{
        int cpu, i;
        unsigned long sum;
        static unsigned long cpu_totals[NR_CPUS];

        /* FIXME: do we care that there's no locking here? */
        sum = 0;
        for_each_online_cpu(cpu) {
                cpu_totals[cpu] = 0;
                for (i = 0; i < HvLpEvent_Type_NumTypes; i++) {
                        cpu_totals[cpu] += per_cpu(hvlpevent_counts, cpu)[i];
                }
                sum += cpu_totals[cpu];
        }

        seq_printf(m, "LpEventQueue 0\n");
        seq_printf(m, "  events processed:\t%lu\n", sum);

        for (i = 0; i < HvLpEvent_Type_NumTypes; ++i) {
                sum = 0;
                for_each_online_cpu(cpu) {
                        sum += per_cpu(hvlpevent_counts, cpu)[i];
                }

                seq_printf(m, "    %-20s %10lu\n", event_types[i], sum);
        }

        seq_printf(m, "\n  events processed by processor:\n");

        for_each_online_cpu(cpu) {
                seq_printf(m, "    CPU%02d  %10lu\n", cpu, cpu_totals[cpu]);
        }

        return 0;
}

static int proc_lpevents_open(struct inode *inode, struct file *file)
{
        return single_open(file, proc_lpevents_show, NULL);
}

static const struct file_operations proc_lpevents_operations = {
        .open           = proc_lpevents_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int __init proc_lpevents_init(void)
{
        if (!firmware_has_feature(FW_FEATURE_ISERIES))
                return 0;

        proc_create("iSeries/lpevents", S_IFREG|S_IRUGO, NULL,
                    &proc_lpevents_operations);
        return 0;
}
__initcall(proc_lpevents_init);