// SPDX-License-Identifier: GPL-2.0+
/*
 * ipmi_si.c
 *
 * The interface to the IPMI driver for the system interfaces (KCS, SMIC,
 * BT).
 *
 * Author: MontaVista Software, Inc.
 *         Corey Minyard <minyard@mvista.com>
 *         source@mvista.com
 *
 * Copyright 2002 MontaVista Software Inc.
 * Copyright 2006 IBM Corp., Christian Krafft <krafft@de.ibm.com>
 */

/*
 * This file holds the "policy" for the interface to the SMI state
 * machine.  It does the configuration, handles timers and interrupts,
 * and drives the real SMI state machine.
 */

#define pr_fmt(fmt) "ipmi_si: " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/timer.h>
#include <linux/errno.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/mutex.h>
#include <linux/kthread.h>
#include <asm/irq.h>
#include <linux/interrupt.h>
#include <linux/rcupdate.h>
#include <linux/ipmi.h>
#include <linux/ipmi_smi.h>
#include "ipmi_si.h"
#include "ipmi_si_sm.h"
#include <linux/string.h>
#include <linux/ctype.h>

/* Measure times between events in the driver. */
#undef DEBUG_TIMING

/* Call every 10 ms. */
#define SI_TIMEOUT_TIME_USEC    10000
#define SI_USEC_PER_JIFFY       (1000000/HZ)
#define SI_TIMEOUT_JIFFIES      (SI_TIMEOUT_TIME_USEC/SI_USEC_PER_JIFFY)
#define SI_SHORT_TIMEOUT_USEC  250 /* .25ms when the SM request a
                                      short timeout */

enum si_intf_state {
        SI_NORMAL,
        SI_GETTING_FLAGS,
        SI_GETTING_EVENTS,
        SI_CLEARING_FLAGS,
        SI_GETTING_MESSAGES,
        SI_CHECKING_ENABLES,
        SI_SETTING_ENABLES
        /* FIXME - add watchdog stuff. */
};

/* Some BT-specific defines we need here. */
#define IPMI_BT_INTMASK_REG             2
#define IPMI_BT_INTMASK_CLEAR_IRQ_BIT   2
#define IPMI_BT_INTMASK_ENABLE_IRQ_BIT  1

/* 'invalid' to allow a firmware-specified interface to be disabled */
const char *const si_to_str[] = { "invalid", "kcs", "smic", "bt", NULL };

static bool initialized;

/*
 * Indexes into stats[] in smi_info below.
 */
enum si_stat_indexes {
        /*
         * Number of times the driver requested a timer while an operation
         * was in progress.
         */
        SI_STAT_short_timeouts = 0,

        /*
         * Number of times the driver requested a timer while nothing was in
         * progress.
         */
        SI_STAT_long_timeouts,

        /* Number of times the interface was idle while being polled. */
        SI_STAT_idles,

        /* Number of interrupts the driver handled. */
        SI_STAT_interrupts,

        /* Number of time the driver got an ATTN from the hardware. */
        SI_STAT_attentions,

        /* Number of times the driver requested flags from the hardware. */
        SI_STAT_flag_fetches,

        /* Number of times the hardware didn't follow the state machine. */
        SI_STAT_hosed_count,

        /* Number of completed messages. */
        SI_STAT_complete_transactions,

        /* Number of IPMI events received from the hardware. */
        SI_STAT_events,

        /* Number of watchdog pretimeouts. */
        SI_STAT_watchdog_pretimeouts,

        /* Number of asynchronous messages received. */
        SI_STAT_incoming_messages,


        /* This *must* remain last, add new values above this. */
        SI_NUM_STATS
};

struct smi_info {
        int                    si_num;
        struct ipmi_smi        *intf;
        struct si_sm_data      *si_sm;
        const struct si_sm_handlers *handlers;
        spinlock_t             si_lock;
        struct ipmi_smi_msg    *waiting_msg;
        struct ipmi_smi_msg    *curr_msg;
        enum si_intf_state     si_state;

        /*
         * Used to handle the various types of I/O that can occur with
         * IPMI
         */
        struct si_sm_io io;

        /*
         * Per-OEM handler, called from handle_flags().  Returns 1
         * when handle_flags() needs to be re-run or 0 indicating it
         * set si_state itself.
         */
        int (*oem_data_avail_handler)(struct smi_info *smi_info);

        /*
         * Flags from the last GET_MSG_FLAGS command, used when an ATTN
         * is set to hold the flags until we are done handling everything
         * from the flags.
         */
#define RECEIVE_MSG_AVAIL       0x01
#define EVENT_MSG_BUFFER_FULL   0x02
#define WDT_PRE_TIMEOUT_INT     0x08
#define OEM0_DATA_AVAIL     0x20
#define OEM1_DATA_AVAIL     0x40
#define OEM2_DATA_AVAIL     0x80
#define OEM_DATA_AVAIL      (OEM0_DATA_AVAIL | \
                             OEM1_DATA_AVAIL | \
                             OEM2_DATA_AVAIL)
        unsigned char       msg_flags;

        /* Does the BMC have an event buffer? */
        bool                has_event_buffer;

        /*
         * If set to true, this will request events the next time the
         * state machine is idle.
         */
        atomic_t            req_events;

        /*
         * If true, run the state machine to completion on every send
         * call.  Generally used after a panic to make sure stuff goes
         * out.
         */
        bool                run_to_completion;

        /* The timer for this si. */
        struct timer_list   si_timer;

        /* This flag is set, if the timer can be set */
        bool                timer_can_start;

        /* This flag is set, if the timer is running (timer_pending() isn't enough) */
        bool                timer_running;

        /* The time (in jiffies) the last timeout occurred at. */
        unsigned long       last_timeout_jiffies;

        /* Are we waiting for the events, pretimeouts, received msgs? */
        atomic_t            need_watch;

        /*
         * The driver will disable interrupts when it gets into a
         * situation where it cannot handle messages due to lack of
         * memory.  Once that situation clears up, it will re-enable
         * interrupts.
         */
        bool interrupt_disabled;

        /*
         * Does the BMC support events?
         */
        bool supports_event_msg_buff;

        /*
         * Can we disable interrupts the global enables receive irq
         * bit?  There are currently two forms of brokenness, some
         * systems cannot disable the bit (which is technically within
         * the spec but a bad idea) and some systems have the bit
         * forced to zero even though interrupts work (which is
         * clearly outside the spec).  The next bool tells which form
         * of brokenness is present.
         */
        bool cannot_disable_irq;

        /*
         * Some systems are broken and cannot set the irq enable
         * bit, even if they support interrupts.
         */
        bool irq_enable_broken;

        /* Is the driver in maintenance mode? */
        bool in_maintenance_mode;

        /*
         * Did we get an attention that we did not handle?
         */
        bool got_attn;

        /* From the get device id response... */
        struct ipmi_device_id device_id;

        /* Have we added the device group to the device? */
        bool dev_group_added;

        /* Counters and things for the proc filesystem. */
        atomic_t stats[SI_NUM_STATS];

        struct task_struct *thread;

        struct list_head link;
};

#define smi_inc_stat(smi, stat) \
        atomic_inc(&(smi)->stats[SI_STAT_ ## stat])
#define smi_get_stat(smi, stat) \
        ((unsigned int) atomic_read(&(smi)->stats[SI_STAT_ ## stat]))

#define IPMI_MAX_INTFS 4
static int force_kipmid[IPMI_MAX_INTFS];
static int num_force_kipmid;

static unsigned int kipmid_max_busy_us[IPMI_MAX_INTFS];
static int num_max_busy_us;

static bool unload_when_empty = true;

static int try_smi_init(struct smi_info *smi);
static void cleanup_one_si(struct smi_info *smi_info);
static void cleanup_ipmi_si(void);

#ifdef DEBUG_TIMING
void debug_timestamp(char *msg)
{
        struct timespec64 t;

        ktime_get_ts64(&t);
        pr_debug("**%s: %lld.%9.9ld\n", msg, t.tv_sec, t.tv_nsec);
}
#else
#define debug_timestamp(x)
#endif

static ATOMIC_NOTIFIER_HEAD(xaction_notifier_list);
static int register_xaction_notifier(struct notifier_block *nb)
{
        return atomic_notifier_chain_register(&xaction_notifier_list, nb);
}

static void deliver_recv_msg(struct smi_info *smi_info,
                             struct ipmi_smi_msg *msg)
{
        /* Deliver the message to the upper layer. */
        ipmi_smi_msg_received(smi_info->intf, msg);
}

static void return_hosed_msg(struct smi_info *smi_info, int cCode)
{
        struct ipmi_smi_msg *msg = smi_info->curr_msg;

        if (cCode < 0 || cCode > IPMI_ERR_UNSPECIFIED)
                cCode = IPMI_ERR_UNSPECIFIED;
        /* else use it as is */

        /* Make it a response */
        msg->rsp[0] = msg->data[0] | 4;
        msg->rsp[1] = msg->data[1];
        msg->rsp[2] = cCode;
        msg->rsp_size = 3;

        smi_info->curr_msg = NULL;
        deliver_recv_msg(smi_info, msg);
}

static enum si_sm_result start_next_msg(struct smi_info *smi_info)
{
        int              rv;

        if (!smi_info->waiting_msg) {
                smi_info->curr_msg = NULL;
                rv = SI_SM_IDLE;
        } else {
                int err;

                smi_info->curr_msg = smi_info->waiting_msg;
                smi_info->waiting_msg = NULL;
                debug_timestamp("Start2");
                err = atomic_notifier_call_chain(&xaction_notifier_list,
                                0, smi_info);
                if (err & NOTIFY_STOP_MASK) {
                        rv = SI_SM_CALL_WITHOUT_DELAY;
                        goto out;
                }
                err = smi_info->handlers->start_transaction(
                        smi_info->si_sm,
                        smi_info->curr_msg->data,
                        smi_info->curr_msg->data_size);
                if (err)
                        return_hosed_msg(smi_info, err);

                rv = SI_SM_CALL_WITHOUT_DELAY;
        }
out:
        return rv;
}

static void smi_mod_timer(struct smi_info *smi_info, unsigned long new_val)
{
        if (!smi_info->timer_can_start)
                return;
        smi_info->last_timeout_jiffies = jiffies;
        mod_timer(&smi_info->si_timer, new_val);
        smi_info->timer_running = true;
}

/*
 * Start a new message and (re)start the timer and thread.
 */
static void start_new_msg(struct smi_info *smi_info, unsigned char *msg,
                          unsigned int size)
{
        smi_mod_timer(smi_info, jiffies + SI_TIMEOUT_JIFFIES);

        if (smi_info->thread)
                wake_up_process(smi_info->thread);

        smi_info->handlers->start_transaction(smi_info->si_sm, msg, size);
}

static void start_check_enables(struct smi_info *smi_info)
{
        unsigned char msg[2];

        msg[0] = (IPMI_NETFN_APP_REQUEST << 2);
        msg[1] = IPMI_GET_BMC_GLOBAL_ENABLES_CMD;

        start_new_msg(smi_info, msg, 2);
        smi_info->si_state = SI_CHECKING_ENABLES;
}

static void start_clear_flags(struct smi_info *smi_info)
{
        unsigned char msg[3];

        /* Make sure the watchdog pre-timeout flag is not set at startup. */
        msg[0] = (IPMI_NETFN_APP_REQUEST << 2);
        msg[1] = IPMI_CLEAR_MSG_FLAGS_CMD;
        msg[2] = WDT_PRE_TIMEOUT_INT;

        start_new_msg(smi_info, msg, 3);
        smi_info->si_state = SI_CLEARING_FLAGS;
}

static void start_getting_msg_queue(struct smi_info *smi_info)
{
        smi_info->curr_msg->data[0] = (IPMI_NETFN_APP_REQUEST << 2);
        smi_info->curr_msg->data[1] = IPMI_GET_MSG_CMD;
        smi_info->curr_msg->data_size = 2;

        start_new_msg(smi_info, smi_info->curr_msg->data,
                      smi_info->curr_msg->data_size);
        smi_info->si_state = SI_GETTING_MESSAGES;
}

static void start_getting_events(struct smi_info *smi_info)
{
        smi_info->curr_msg->data[0] = (IPMI_NETFN_APP_REQUEST << 2);
        smi_info->curr_msg->data[1] = IPMI_READ_EVENT_MSG_BUFFER_CMD;
        smi_info->curr_msg->data_size = 2;

        start_new_msg(smi_info, smi_info->curr_msg->data,
                      smi_info->curr_msg->data_size);
        smi_info->si_state = SI_GETTING_EVENTS;
}

/*
 * When we have a situtaion where we run out of memory and cannot
 * allocate messages, we just leave them in the BMC and run the system
 * polled until we can allocate some memory.  Once we have some
 * memory, we will re-enable the interrupt.
 *
 * Note that we cannot just use disable_irq(), since the interrupt may
 * be shared.
 */
static inline bool disable_si_irq(struct smi_info *smi_info)
{
        if ((smi_info->io.irq) && (!smi_info->interrupt_disabled)) {
                smi_info->interrupt_disabled = true;
                start_check_enables(smi_info);
                return true;
        }
        return false;
}

static inline bool enable_si_irq(struct smi_info *smi_info)
{
        if ((smi_info->io.irq) && (smi_info->interrupt_disabled)) {
                smi_info->interrupt_disabled = false;
                start_check_enables(smi_info);
                return true;
        }
        return false;
}

/*
 * Allocate a message.  If unable to allocate, start the interrupt
 * disable process and return NULL.  If able to allocate but
 * interrupts are disabled, free the message and return NULL after
 * starting the interrupt enable process.
 */
static struct ipmi_smi_msg *alloc_msg_handle_irq(struct smi_info *smi_info)
{
        struct ipmi_smi_msg *msg;

        msg = ipmi_alloc_smi_msg();
        if (!msg) {
                if (!disable_si_irq(smi_info))
                        smi_info->si_state = SI_NORMAL;
        } else if (enable_si_irq(smi_info)) {
                ipmi_free_smi_msg(msg);
                msg = NULL;
        }
        return msg;
}

static void handle_flags(struct smi_info *smi_info)
{
retry:
        if (smi_info->msg_flags & WDT_PRE_TIMEOUT_INT) {
                /* Watchdog pre-timeout */
                smi_inc_stat(smi_info, watchdog_pretimeouts);

                start_clear_flags(smi_info);
                smi_info->msg_flags &= ~WDT_PRE_TIMEOUT_INT;
                ipmi_smi_watchdog_pretimeout(smi_info->intf);
        } else if (smi_info->msg_flags & RECEIVE_MSG_AVAIL) {
                /* Messages available. */
                smi_info->curr_msg = alloc_msg_handle_irq(smi_info);
                if (!smi_info->curr_msg)
                        return;

                start_getting_msg_queue(smi_info);
        } else if (smi_info->msg_flags & EVENT_MSG_BUFFER_FULL) {
                /* Events available. */
                smi_info->curr_msg = alloc_msg_handle_irq(smi_info);
                if (!smi_info->curr_msg)
                        return;

                start_getting_events(smi_info);
        } else if (smi_info->msg_flags & OEM_DATA_AVAIL &&
                   smi_info->oem_data_avail_handler) {
                if (smi_info->oem_data_avail_handler(smi_info))
                        goto retry;
        } else
                smi_info->si_state = SI_NORMAL;
}

/*
 * Global enables we care about.
 */
#define GLOBAL_ENABLES_MASK (IPMI_BMC_EVT_MSG_BUFF | IPMI_BMC_RCV_MSG_INTR | \
                             IPMI_BMC_EVT_MSG_INTR)

static u8 current_global_enables(struct smi_info *smi_info, u8 base,
                                 bool *irq_on)
{
        u8 enables = 0;

        if (smi_info->supports_event_msg_buff)
                enables |= IPMI_BMC_EVT_MSG_BUFF;

        if (((smi_info->io.irq && !smi_info->interrupt_disabled) ||
             smi_info->cannot_disable_irq) &&
            !smi_info->irq_enable_broken)
                enables |= IPMI_BMC_RCV_MSG_INTR;

        if (smi_info->supports_event_msg_buff &&
            smi_info->io.irq && !smi_info->interrupt_disabled &&
            !smi_info->irq_enable_broken)
                enables |= IPMI_BMC_EVT_MSG_INTR;

        *irq_on = enables & (IPMI_BMC_EVT_MSG_INTR | IPMI_BMC_RCV_MSG_INTR);

        return enables;
}

static void check_bt_irq(struct smi_info *smi_info, bool irq_on)
{
        u8 irqstate = smi_info->io.inputb(&smi_info->io, IPMI_BT_INTMASK_REG);

        irqstate &= IPMI_BT_INTMASK_ENABLE_IRQ_BIT;

        if ((bool)irqstate == irq_on)
                return;

        if (irq_on)
                smi_info->io.outputb(&smi_info->io, IPMI_BT_INTMASK_REG,
                                     IPMI_BT_INTMASK_ENABLE_IRQ_BIT);
        else
                smi_info->io.outputb(&smi_info->io, IPMI_BT_INTMASK_REG, 0);
}

static void handle_transaction_done(struct smi_info *smi_info)
{
        struct ipmi_smi_msg *msg;

        debug_timestamp("Done");
        switch (smi_info->si_state) {
        case SI_NORMAL:
                if (!smi_info->curr_msg)
                        break;

                smi_info->curr_msg->rsp_size
                        = smi_info->handlers->get_result(
                                smi_info->si_sm,
                                smi_info->curr_msg->rsp,
                                IPMI_MAX_MSG_LENGTH);

                /*
                 * Do this here becase deliver_recv_msg() releases the
                 * lock, and a new message can be put in during the
                 * time the lock is released.
                 */
                msg = smi_info->curr_msg;
                smi_info->curr_msg = NULL;
                deliver_recv_msg(smi_info, msg);
                break;

        case SI_GETTING_FLAGS:
        {
                unsigned char msg[4];
                unsigned int  len;

                /* We got the flags from the SMI, now handle them. */
                len = smi_info->handlers->get_result(smi_info->si_sm, msg, 4);
                if (msg[2] != 0) {
                        /* Error fetching flags, just give up for now. */
                        smi_info->si_state = SI_NORMAL;
                } else if (len < 4) {
                        /*
                         * Hmm, no flags.  That's technically illegal, but
                         * don't use uninitialized data.
                         */
                        smi_info->si_state = SI_NORMAL;
                } else {
                        smi_info->msg_flags = msg[3];
                        handle_flags(smi_info);
                }
                break;
        }

        case SI_CLEARING_FLAGS:
        {
                unsigned char msg[3];

                /* We cleared the flags. */
                smi_info->handlers->get_result(smi_info->si_sm, msg, 3);
                if (msg[2] != 0) {
                        /* Error clearing flags */
                        dev_warn(smi_info->io.dev,
                                 "Error clearing flags: %2.2x\n", msg[2]);
                }
                smi_info->si_state = SI_NORMAL;
                break;
        }

        case SI_GETTING_EVENTS:
        {
                smi_info->curr_msg->rsp_size
                        = smi_info->handlers->get_result(
                                smi_info->si_sm,
                                smi_info->curr_msg->rsp,
                                IPMI_MAX_MSG_LENGTH);

                /*
                 * Do this here becase deliver_recv_msg() releases the
                 * lock, and a new message can be put in during the
                 * time the lock is released.
                 */
                msg = smi_info->curr_msg;
                smi_info->curr_msg = NULL;
                if (msg->rsp[2] != 0) {
                        /* Error getting event, probably done. */
                        msg->done(msg);

                        /* Take off the event flag. */
                        smi_info->msg_flags &= ~EVENT_MSG_BUFFER_FULL;
                        handle_flags(smi_info);
                } else {
                        smi_inc_stat(smi_info, events);

                        /*
                         * Do this before we deliver the message
                         * because delivering the message releases the
                         * lock and something else can mess with the
                         * state.
                         */
                        handle_flags(smi_info);

                        deliver_recv_msg(smi_info, msg);
                }
                break;
        }

        case SI_GETTING_MESSAGES:
        {
                smi_info->curr_msg->rsp_size
                        = smi_info->handlers->get_result(
                                smi_info->si_sm,
                                smi_info->curr_msg->rsp,
                                IPMI_MAX_MSG_LENGTH);

                /*
                 * Do this here becase deliver_recv_msg() releases the
                 * lock, and a new message can be put in during the
                 * time the lock is released.
                 */
                msg = smi_info->curr_msg;
                smi_info->curr_msg = NULL;
                if (msg->rsp[2] != 0) {
                        /* Error getting event, probably done. */
                        msg->done(msg);

                        /* Take off the msg flag. */
                        smi_info->msg_flags &= ~RECEIVE_MSG_AVAIL;
                        handle_flags(smi_info);
                } else {
                        smi_inc_stat(smi_info, incoming_messages);

                        /*
                         * Do this before we deliver the message
                         * because delivering the message releases the
                         * lock and something else can mess with the
                         * state.
                         */
                        handle_flags(smi_info);

                        deliver_recv_msg(smi_info, msg);
                }
                break;
        }

        case SI_CHECKING_ENABLES:
        {
                unsigned char msg[4];
                u8 enables;
                bool irq_on;

                /* We got the flags from the SMI, now handle them. */
                smi_info->handlers->get_result(smi_info->si_sm, msg, 4);
                if (msg[2] != 0) {
                        dev_warn(smi_info->io.dev,
                                 "Couldn't get irq info: %x.\n", msg[2]);
                        dev_warn(smi_info->io.dev,
                                 "Maybe ok, but ipmi might run very slowly.\n");
                        smi_info->si_state = SI_NORMAL;
                        break;
                }
                enables = current_global_enables(smi_info, 0, &irq_on);
                if (smi_info->io.si_type == SI_BT)
                        /* BT has its own interrupt enable bit. */
                        check_bt_irq(smi_info, irq_on);
                if (enables != (msg[3] & GLOBAL_ENABLES_MASK)) {
                        /* Enables are not correct, fix them. */
                        msg[0] = (IPMI_NETFN_APP_REQUEST << 2);
                        msg[1] = IPMI_SET_BMC_GLOBAL_ENABLES_CMD;
                        msg[2] = enables | (msg[3] & ~GLOBAL_ENABLES_MASK);
                        smi_info->handlers->start_transaction(
                                smi_info->si_sm, msg, 3);
                        smi_info->si_state = SI_SETTING_ENABLES;
                } else if (smi_info->supports_event_msg_buff) {
                        smi_info->curr_msg = ipmi_alloc_smi_msg();
                        if (!smi_info->curr_msg) {
                                smi_info->si_state = SI_NORMAL;
                                break;
                        }
                        start_getting_events(smi_info);
                } else {
                        smi_info->si_state = SI_NORMAL;
                }
                break;
        }

        case SI_SETTING_ENABLES:
        {
                unsigned char msg[4];

                smi_info->handlers->get_result(smi_info->si_sm, msg, 4);
                if (msg[2] != 0)
                        dev_warn(smi_info->io.dev,
                                 "Could not set the global enables: 0x%x.\n",
                                 msg[2]);

                if (smi_info->supports_event_msg_buff) {
                        smi_info->curr_msg = ipmi_alloc_smi_msg();
                        if (!smi_info->curr_msg) {
                                smi_info->si_state = SI_NORMAL;
                                break;
                        }
                        start_getting_events(smi_info);
                } else {
                        smi_info->si_state = SI_NORMAL;
                }
                break;
        }
        }
}

/*
 * Called on timeouts and events.  Timeouts should pass the elapsed
 * time, interrupts should pass in zero.  Must be called with
 * si_lock held and interrupts disabled.
 */
static enum si_sm_result smi_event_handler(struct smi_info *smi_info,
                                           int time)
{
        enum si_sm_result si_sm_result;

restart:
        /*
         * There used to be a loop here that waited a little while
         * (around 25us) before giving up.  That turned out to be
         * pointless, the minimum delays I was seeing were in the 300us
         * range, which is far too long to wait in an interrupt.  So
         * we just run until the state machine tells us something
         * happened or it needs a delay.
         */
        si_sm_result = smi_info->handlers->event(smi_info->si_sm, time);
        time = 0;
        while (si_sm_result == SI_SM_CALL_WITHOUT_DELAY)
                si_sm_result = smi_info->handlers->event(smi_info->si_sm, 0);

        if (si_sm_result == SI_SM_TRANSACTION_COMPLETE) {
                smi_inc_stat(smi_info, complete_transactions);

                handle_transaction_done(smi_info);
                goto restart;
        } else if (si_sm_result == SI_SM_HOSED) {
                smi_inc_stat(smi_info, hosed_count);

                /*
                 * Do the before return_hosed_msg, because that
                 * releases the lock.
                 */
                smi_info->si_state = SI_NORMAL;
                if (smi_info->curr_msg != NULL) {
                        /*
                         * If we were handling a user message, format
                         * a response to send to the upper layer to
                         * tell it about the error.
                         */
                        return_hosed_msg(smi_info, IPMI_ERR_UNSPECIFIED);
                }
                goto restart;
        }

        /*
         * We prefer handling attn over new messages.  But don't do
         * this if there is not yet an upper layer to handle anything.
         */
        if (si_sm_result == SI_SM_ATTN || smi_info->got_attn) {
                unsigned char msg[2];

                if (smi_info->si_state != SI_NORMAL) {
                        /*
                         * We got an ATTN, but we are doing something else.
                         * Handle the ATTN later.
                         */
                        smi_info->got_attn = true;
                } else {
                        smi_info->got_attn = false;
                        smi_inc_stat(smi_info, attentions);

                        /*
                         * Got a attn, send down a get message flags to see
                         * what's causing it.  It would be better to handle
                         * this in the upper layer, but due to the way
                         * interrupts work with the SMI, that's not really
                         * possible.
                         */
                        msg[0] = (IPMI_NETFN_APP_REQUEST << 2);
                        msg[1] = IPMI_GET_MSG_FLAGS_CMD;

                        start_new_msg(smi_info, msg, 2);
                        smi_info->si_state = SI_GETTING_FLAGS;
                        goto restart;
                }
        }

        /* If we are currently idle, try to start the next message. */
        if (si_sm_result == SI_SM_IDLE) {
                smi_inc_stat(smi_info, idles);

                si_sm_result = start_next_msg(smi_info);
                if (si_sm_result != SI_SM_IDLE)
                        goto restart;
        }

        if ((si_sm_result == SI_SM_IDLE)
            && (atomic_read(&smi_info->req_events))) {
                /*
                 * We are idle and the upper layer requested that I fetch
                 * events, so do so.
                 */
                atomic_set(&smi_info->req_events, 0);

                /*
                 * Take this opportunity to check the interrupt and
                 * message enable state for the BMC.  The BMC can be
                 * asynchronously reset, and may thus get interrupts
                 * disable and messages disabled.
                 */
                if (smi_info->supports_event_msg_buff || smi_info->io.irq) {
                        start_check_enables(smi_info);
                } else {
                        smi_info->curr_msg = alloc_msg_handle_irq(smi_info);
                        if (!smi_info->curr_msg)
                                goto out;

                        start_getting_events(smi_info);
                }
                goto restart;
        }

        if (si_sm_result == SI_SM_IDLE && smi_info->timer_running) {
                /* Ok it if fails, the timer will just go off. */
                if (del_timer(&smi_info->si_timer))
                        smi_info->timer_running = false;
        }

out:
        return si_sm_result;
}

static void check_start_timer_thread(struct smi_info *smi_info)
{
        if (smi_info->si_state == SI_NORMAL && smi_info->curr_msg == NULL) {
                smi_mod_timer(smi_info, jiffies + SI_TIMEOUT_JIFFIES);

                if (smi_info->thread)
                        wake_up_process(smi_info->thread);

                start_next_msg(smi_info);
                smi_event_handler(smi_info, 0);
        }
}

static void flush_messages(void *send_info)
{
        struct smi_info *smi_info = send_info;
        enum si_sm_result result;

        /*
         * Currently, this function is called only in run-to-completion
         * mode.  This means we are single-threaded, no need for locks.
         */
        result = smi_event_handler(smi_info, 0);
        while (result != SI_SM_IDLE) {
                udelay(SI_SHORT_TIMEOUT_USEC);
                result = smi_event_handler(smi_info, SI_SHORT_TIMEOUT_USEC);
        }
}

static void sender(void                *send_info,
                   struct ipmi_smi_msg *msg)
{
        struct smi_info   *smi_info = send_info;
        unsigned long     flags;

        debug_timestamp("Enqueue");

        if (smi_info->run_to_completion) {
                /*
                 * If we are running to completion, start it.  Upper
                 * layer will call flush_messages to clear it out.
                 */
                smi_info->waiting_msg = msg;
                return;
        }

        spin_lock_irqsave(&smi_info->si_lock, flags);
        /*
         * The following two lines don't need to be under the lock for
         * the lock's sake, but they do need SMP memory barriers to
         * avoid getting things out of order.  We are already claiming
         * the lock, anyway, so just do it under the lock to avoid the
         * ordering problem.
         */
        BUG_ON(smi_info->waiting_msg);
        smi_info->waiting_msg = msg;
        check_start_timer_thread(smi_info);
        spin_unlock_irqrestore(&smi_info->si_lock, flags);
}

static void set_run_to_completion(void *send_info, bool i_run_to_completion)
{
        struct smi_info   *smi_info = send_info;

        smi_info->run_to_completion = i_run_to_completion;
        if (i_run_to_completion)
                flush_messages(smi_info);
}

/*
 * Use -1 as a special constant to tell that we are spinning in kipmid
 * looking for something and not delaying between checks
 */
#define IPMI_TIME_NOT_BUSY ns_to_ktime(-1ull)
static inline bool ipmi_thread_busy_wait(enum si_sm_result smi_result,
                                         const struct smi_info *smi_info,
                                         ktime_t *busy_until)
{
        unsigned int max_busy_us = 0;

        if (smi_info->si_num < num_max_busy_us)
                max_busy_us = kipmid_max_busy_us[smi_info->si_num];
        if (max_busy_us == 0 || smi_result != SI_SM_CALL_WITH_DELAY)
                *busy_until = IPMI_TIME_NOT_BUSY;
        else if (*busy_until == IPMI_TIME_NOT_BUSY) {
                *busy_until = ktime_get() + max_busy_us * NSEC_PER_USEC;
        } else {
                if (unlikely(ktime_get() > *busy_until)) {
                        *busy_until = IPMI_TIME_NOT_BUSY;
                        return false;
                }
        }
        return true;
}


/*
 * A busy-waiting loop for speeding up IPMI operation.
 *
 * Lousy hardware makes this hard.  This is only enabled for systems
 * that are not BT and do not have interrupts.  It starts spinning
 * when an operation is complete or until max_busy tells it to stop
 * (if that is enabled).  See the paragraph on kimid_max_busy_us in
 * Documentation/driver-api/ipmi.rst for details.
 */
static int ipmi_thread(void *data)
{
        struct smi_info *smi_info = data;
        unsigned long flags;
        enum si_sm_result smi_result;
        ktime_t busy_until = IPMI_TIME_NOT_BUSY;

        set_user_nice(current, MAX_NICE);
        while (!kthread_should_stop()) {
                int busy_wait;

                spin_lock_irqsave(&(smi_info->si_lock), flags);
                smi_result = smi_event_handler(smi_info, 0);

                /*
                 * If the driver is doing something, there is a possible
                 * race with the timer.  If the timer handler see idle,
                 * and the thread here sees something else, the timer
                 * handler won't restart the timer even though it is
                 * required.  So start it here if necessary.
                 */
                if (smi_result != SI_SM_IDLE && !smi_info->timer_running)
                        smi_mod_timer(smi_info, jiffies + SI_TIMEOUT_JIFFIES);

                spin_unlock_irqrestore(&(smi_info->si_lock), flags);
                busy_wait = ipmi_thread_busy_wait(smi_result, smi_info,
                                                  &busy_until);

                if (smi_result == SI_SM_CALL_WITHOUT_DELAY) {
                        ; /* do nothing */
                } else if (smi_result == SI_SM_CALL_WITH_DELAY && busy_wait) {
                        /*
                         * In maintenance mode we run as fast as
                         * possible to allow firmware updates to
                         * complete as fast as possible, but normally
                         * don't bang on the scheduler.
                         */
                        if (smi_info->in_maintenance_mode)
                                schedule();
                        else
                                usleep_range(100, 200);
                } else if (smi_result == SI_SM_IDLE) {
                        if (atomic_read(&smi_info->need_watch)) {
                                schedule_timeout_interruptible(100);
                        } else {
                                /* Wait to be woken up when we are needed. */
                                __set_current_state(TASK_INTERRUPTIBLE);
                                schedule();
                        }
                } else {
                        schedule_timeout_interruptible(1);
                }
        }
        return 0;
}


static void poll(void *send_info)
{
        struct smi_info *smi_info = send_info;
        unsigned long flags = 0;
        bool run_to_completion = smi_info->run_to_completion;

        /*
         * Make sure there is some delay in the poll loop so we can
         * drive time forward and timeout things.
         */
        udelay(10);
        if (!run_to_completion)
                spin_lock_irqsave(&smi_info->si_lock, flags);
        smi_event_handler(smi_info, 10);
        if (!run_to_completion)
                spin_unlock_irqrestore(&smi_info->si_lock, flags);
}

static void request_events(void *send_info)
{
        struct smi_info *smi_info = send_info;

        if (!smi_info->has_event_buffer)
                return;

        atomic_set(&smi_info->req_events, 1);
}

static void set_need_watch(void *send_info, unsigned int watch_mask)
{
        struct smi_info *smi_info = send_info;
        unsigned long flags;
        int enable;

        enable = !!watch_mask;

        atomic_set(&smi_info->need_watch, enable);
        spin_lock_irqsave(&smi_info->si_lock, flags);
        check_start_timer_thread(smi_info);
        spin_unlock_irqrestore(&smi_info->si_lock, flags);
}

static void smi_timeout(struct timer_list *t)
{
        struct smi_info   *smi_info = from_timer(smi_info, t, si_timer);
        enum si_sm_result smi_result;
        unsigned long     flags;
        unsigned long     jiffies_now;
        long              time_diff;
        long              timeout;

        spin_lock_irqsave(&(smi_info->si_lock), flags);
        debug_timestamp("Timer");

        jiffies_now = jiffies;
        time_diff = (((long)jiffies_now - (long)smi_info->last_timeout_jiffies)
                     * SI_USEC_PER_JIFFY);
        smi_result = smi_event_handler(smi_info, time_diff);

        if ((smi_info->io.irq) && (!smi_info->interrupt_disabled)) {
                /* Running with interrupts, only do long timeouts. */
                timeout = jiffies + SI_TIMEOUT_JIFFIES;
                smi_inc_stat(smi_info, long_timeouts);
                goto do_mod_timer;
        }

        /*
         * If the state machine asks for a short delay, then shorten
         * the timer timeout.
         */
        if (smi_result == SI_SM_CALL_WITH_DELAY) {
                smi_inc_stat(smi_info, short_timeouts);
                timeout = jiffies + 1;
        } else {
                smi_inc_stat(smi_info, long_timeouts);
                timeout = jiffies + SI_TIMEOUT_JIFFIES;
        }

do_mod_timer:
        if (smi_result != SI_SM_IDLE)
                smi_mod_timer(smi_info, timeout);
        else
                smi_info->timer_running = false;
        spin_unlock_irqrestore(&(smi_info->si_lock), flags);
}

irqreturn_t ipmi_si_irq_handler(int irq, void *data)
{
        struct smi_info *smi_info = data;
        unsigned long   flags;

        if (smi_info->io.si_type == SI_BT)
                /* We need to clear the IRQ flag for the BT interface. */
                smi_info->io.outputb(&smi_info->io, IPMI_BT_INTMASK_REG,
                                     IPMI_BT_INTMASK_CLEAR_IRQ_BIT
                                     | IPMI_BT_INTMASK_ENABLE_IRQ_BIT);

        spin_lock_irqsave(&(smi_info->si_lock), flags);

        smi_inc_stat(smi_info, interrupts);

        debug_timestamp("Interrupt");

        smi_event_handler(smi_info, 0);
        spin_unlock_irqrestore(&(smi_info->si_lock), flags);
        return IRQ_HANDLED;
}

static int smi_start_processing(void            *send_info,
                                struct ipmi_smi *intf)
{
        struct smi_info *new_smi = send_info;
        int             enable = 0;

        new_smi->intf = intf;

        /* Set up the timer that drives the interface. */
        timer_setup(&new_smi->si_timer, smi_timeout, 0);
        new_smi->timer_can_start = true;
        smi_mod_timer(new_smi, jiffies + SI_TIMEOUT_JIFFIES);

        /* Try to claim any interrupts. */
        if (new_smi->io.irq_setup) {
                new_smi->io.irq_handler_data = new_smi;
                new_smi->io.irq_setup(&new_smi->io);
        }

        /*
         * Check if the user forcefully enabled the daemon.
         */
        if (new_smi->si_num < num_force_kipmid)
                enable = force_kipmid[new_smi->si_num];
        /*
         * The BT interface is efficient enough to not need a thread,
         * and there is no need for a thread if we have interrupts.
         */
        else if ((new_smi->io.si_type != SI_BT) && (!new_smi->io.irq))
                enable = 1;

        if (enable) {
                new_smi->thread = kthread_run(ipmi_thread, new_smi,
                                              "kipmi%d", new_smi->si_num);
                if (IS_ERR(new_smi->thread)) {
                        dev_notice(new_smi->io.dev,
                                   "Could not start kernel thread due to error %ld, only using timers to drive the interface\n",
                                   PTR_ERR(new_smi->thread));
                        new_smi->thread = NULL;
                }
        }

        return 0;
}

static int get_smi_info(void *send_info, struct ipmi_smi_info *data)
{
        struct smi_info *smi = send_info;

        data->addr_src = smi->io.addr_source;
        data->dev = smi->io.dev;
        data->addr_info = smi->io.addr_info;
        get_device(smi->io.dev);

        return 0;
}

static void set_maintenance_mode(void *send_info, bool enable)
{
        struct smi_info   *smi_info = send_info;

        if (!enable)
                atomic_set(&smi_info->req_events, 0);
        smi_info->in_maintenance_mode = enable;
}

static void shutdown_smi(void *send_info);
static const struct ipmi_smi_handlers handlers = {
        .owner                  = THIS_MODULE,
        .start_processing       = smi_start_processing,
        .shutdown               = shutdown_smi,
        .get_smi_info           = get_smi_info,
        .sender                 = sender,
        .request_events         = request_events,
        .set_need_watch         = set_need_watch,
        .set_maintenance_mode   = set_maintenance_mode,
        .set_run_to_completion  = set_run_to_completion,
        .flush_messages         = flush_messages,
        .poll                   = poll,
};

static LIST_HEAD(smi_infos);
static DEFINE_MUTEX(smi_infos_lock);
static int smi_num; /* Used to sequence the SMIs */

static const char * const addr_space_to_str[] = { "i/o", "mem" };

module_param_array(force_kipmid, int, &num_force_kipmid, 0);
MODULE_PARM_DESC(force_kipmid,
                 "Force the kipmi daemon to be enabled (1) or disabled(0).  Normally the IPMI driver auto-detects this, but the value may be overridden by this parm.");
module_param(unload_when_empty, bool, 0);
MODULE_PARM_DESC(unload_when_empty,
                 "Unload the module if no interfaces are specified or found, default is 1.  Setting to 0 is useful for hot add of devices using hotmod.");
module_param_array(kipmid_max_busy_us, uint, &num_max_busy_us, 0644);
MODULE_PARM_DESC(kipmid_max_busy_us,
                 "Max time (in microseconds) to busy-wait for IPMI data before sleeping. 0 (default) means to wait forever. Set to 100-500 if kipmid is using up a lot of CPU time.");

void ipmi_irq_finish_setup(struct si_sm_io *io)
{
        if (io->si_type == SI_BT)
                /* Enable the interrupt in the BT interface. */
                io->outputb(io, IPMI_BT_INTMASK_REG,
                            IPMI_BT_INTMASK_ENABLE_IRQ_BIT);
}

void ipmi_irq_start_cleanup(struct si_sm_io *io)
{
        if (io->si_type == SI_BT)
                /* Disable the interrupt in the BT interface. */
                io->outputb(io, IPMI_BT_INTMASK_REG, 0);
}

static void std_irq_cleanup(struct si_sm_io *io)
{
        ipmi_irq_start_cleanup(io);
        free_irq(io->irq, io->irq_handler_data);
}

int ipmi_std_irq_setup(struct si_sm_io *io)
{
        int rv;

        if (!io->irq)
                return 0;

        rv = request_irq(io->irq,
                         ipmi_si_irq_handler,
                         IRQF_SHARED,
                         SI_DEVICE_NAME,
                         io->irq_handler_data);
        if (rv) {
                dev_warn(io->dev, "%s unable to claim interrupt %d, running polled\n",
                         SI_DEVICE_NAME, io->irq);
                io->irq = 0;
        } else {
                io->irq_cleanup = std_irq_cleanup;
                ipmi_irq_finish_setup(io);
                dev_info(io->dev, "Using irq %d\n", io->irq);
        }

        return rv;
}

static int wait_for_msg_done(struct smi_info *smi_info)
{
        enum si_sm_result     smi_result;

        smi_result = smi_info->handlers->event(smi_info->si_sm, 0);
        for (;;) {
                if (smi_result == SI_SM_CALL_WITH_DELAY ||
                    smi_result == SI_SM_CALL_WITH_TICK_DELAY) {
                        schedule_timeout_uninterruptible(1);
                        smi_result = smi_info->handlers->event(
                                smi_info->si_sm, jiffies_to_usecs(1));
                } else if (smi_result == SI_SM_CALL_WITHOUT_DELAY) {
                        smi_result = smi_info->handlers->event(
                                smi_info->si_sm, 0);
                } else
                        break;
        }
        if (smi_result == SI_SM_HOSED)
                /*
                 * We couldn't get the state machine to run, so whatever's at
                 * the port is probably not an IPMI SMI interface.
                 */
                return -ENODEV;

        return 0;
}

static int try_get_dev_id(struct smi_info *smi_info)
{
        unsigned char         msg[2];
        unsigned char         *resp;
        unsigned long         resp_len;
        int                   rv = 0;
        unsigned int          retry_count = 0;

        resp = kmalloc(IPMI_MAX_MSG_LENGTH, GFP_KERNEL);
        if (!resp)
                return -ENOMEM;

        /*
         * Do a Get Device ID command, since it comes back with some
         * useful info.
         */
        msg[0] = IPMI_NETFN_APP_REQUEST << 2;
        msg[1] = IPMI_GET_DEVICE_ID_CMD;

retry:
        smi_info->handlers->start_transaction(smi_info->si_sm, msg, 2);

        rv = wait_for_msg_done(smi_info);
        if (rv)
                goto out;

        resp_len = smi_info->handlers->get_result(smi_info->si_sm,
                                                  resp, IPMI_MAX_MSG_LENGTH);

        /* Check and record info from the get device id, in case we need it. */
        rv = ipmi_demangle_device_id(resp[0] >> 2, resp[1],
                        resp + 2, resp_len - 2, &smi_info->device_id);
        if (rv) {
                /* record completion code */
                unsigned char cc = *(resp + 2);

                if (cc != IPMI_CC_NO_ERROR &&
                    ++retry_count <= GET_DEVICE_ID_MAX_RETRY) {
                        dev_warn(smi_info->io.dev,
                            "BMC returned 0x%2.2x, retry get bmc device id\n",
                            cc);
                        goto retry;
                }
        }

out:
        kfree(resp);
        return rv;
}

static int get_global_enables(struct smi_info *smi_info, u8 *enables)
{
        unsigned char         msg[3];
        unsigned char         *resp;
        unsigned long         resp_len;
        int                   rv;

        resp = kmalloc(IPMI_MAX_MSG_LENGTH, GFP_KERNEL);
        if (!resp)
                return -ENOMEM;

        msg[0] = IPMI_NETFN_APP_REQUEST << 2;
        msg[1] = IPMI_GET_BMC_GLOBAL_ENABLES_CMD;
        smi_info->handlers->start_transaction(smi_info->si_sm, msg, 2);

        rv = wait_for_msg_done(smi_info);
        if (rv) {
                dev_warn(smi_info->io.dev,
                         "Error getting response from get global enables command: %d\n",
                         rv);
                goto out;
        }

        resp_len = smi_info->handlers->get_result(smi_info->si_sm,
                                                  resp, IPMI_MAX_MSG_LENGTH);

        if (resp_len < 4 ||
                        resp[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2 ||
                        resp[1] != IPMI_GET_BMC_GLOBAL_ENABLES_CMD   ||
                        resp[2] != 0) {
                dev_warn(smi_info->io.dev,
                         "Invalid return from get global enables command: %ld %x %x %x\n",
                         resp_len, resp[0], resp[1], resp[2]);
                rv = -EINVAL;
                goto out;
        } else {
                *enables = resp[3];
        }

out:
        kfree(resp);
        return rv;
}

/*
 * Returns 1 if it gets an error from the command.
 */
static int set_global_enables(struct smi_info *smi_info, u8 enables)
{
        unsigned char         msg[3];
        unsigned char         *resp;
        unsigned long         resp_len;
        int                   rv;

        resp = kmalloc(IPMI_MAX_MSG_LENGTH, GFP_KERNEL);
        if (!resp)
                return -ENOMEM;

        msg[0] = IPMI_NETFN_APP_REQUEST << 2;
        msg[1] = IPMI_SET_BMC_GLOBAL_ENABLES_CMD;
        msg[2] = enables;
        smi_info->handlers->start_transaction(smi_info->si_sm, msg, 3);

        rv = wait_for_msg_done(smi_info);
        if (rv) {
                dev_warn(smi_info->io.dev,
                         "Error getting response from set global enables command: %d\n",
                         rv);
                goto out;
        }

        resp_len = smi_info->handlers->get_result(smi_info->si_sm,
                                                  resp, IPMI_MAX_MSG_LENGTH);

        if (resp_len < 3 ||
                        resp[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2 ||
                        resp[1] != IPMI_SET_BMC_GLOBAL_ENABLES_CMD) {
                dev_warn(smi_info->io.dev,
                         "Invalid return from set global enables command: %ld %x %x\n",
                         resp_len, resp[0], resp[1]);
                rv = -EINVAL;
                goto out;
        }

        if (resp[2] != 0)
                rv = 1;

out:
        kfree(resp);
        return rv;
}

/*
 * Some BMCs do not support clearing the receive irq bit in the global
 * enables (even if they don't support interrupts on the BMC).  Check
 * for this and handle it properly.
 */
static void check_clr_rcv_irq(struct smi_info *smi_info)
{
        u8 enables = 0;
        int rv;

        rv = get_global_enables(smi_info, &enables);
        if (!rv) {
                if ((enables & IPMI_BMC_RCV_MSG_INTR) == 0)
                        /* Already clear, should work ok. */
                        return;

                enables &= ~IPMI_BMC_RCV_MSG_INTR;
                rv = set_global_enables(smi_info, enables);
        }

        if (rv < 0) {
                dev_err(smi_info->io.dev,
                        "Cannot check clearing the rcv irq: %d\n", rv);
                return;
        }

        if (rv) {
                /*
                 * An error when setting the event buffer bit means
                 * clearing the bit is not supported.
                 */
                dev_warn(smi_info->io.dev,
                         "The BMC does not support clearing the recv irq bit, compensating, but the BMC needs to be fixed.\n");
                smi_info->cannot_disable_irq = true;
        }
}

/*
 * Some BMCs do not support setting the interrupt bits in the global
 * enables even if they support interrupts.  Clearly bad, but we can
 * compensate.
 */
static void check_set_rcv_irq(struct smi_info *smi_info)
{
        u8 enables = 0;
        int rv;

        if (!smi_info->io.irq)
                return;

        rv = get_global_enables(smi_info, &enables);
        if (!rv) {
                enables |= IPMI_BMC_RCV_MSG_INTR;
                rv = set_global_enables(smi_info, enables);
        }

        if (rv < 0) {
                dev_err(smi_info->io.dev,
                        "Cannot check setting the rcv irq: %d\n", rv);
                return;
        }

        if (rv) {
                /*
                 * An error when setting the event buffer bit means
                 * setting the bit is not supported.
                 */
                dev_warn(smi_info->io.dev,
                         "The BMC does not support setting the recv irq bit, compensating, but the BMC needs to be fixed.\n");
                smi_info->cannot_disable_irq = true;
                smi_info->irq_enable_broken = true;
        }
}

static int try_enable_event_buffer(struct smi_info *smi_info)
{
        unsigned char         msg[3];
        unsigned char         *resp;
        unsigned long         resp_len;
        int                   rv = 0;

        resp = kmalloc(IPMI_MAX_MSG_LENGTH, GFP_KERNEL);
        if (!resp)
                return -ENOMEM;

        msg[0] = IPMI_NETFN_APP_REQUEST << 2;
        msg[1] = IPMI_GET_BMC_GLOBAL_ENABLES_CMD;
        smi_info->handlers->start_transaction(smi_info->si_sm, msg, 2);

        rv = wait_for_msg_done(smi_info);
        if (rv) {
                pr_warn("Error getting response from get global enables command, the event buffer is not enabled\n");
                goto out;
        }

        resp_len = smi_info->handlers->get_result(smi_info->si_sm,
                                                  resp, IPMI_MAX_MSG_LENGTH);

        if (resp_len < 4 ||
                        resp[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2 ||
                        resp[1] != IPMI_GET_BMC_GLOBAL_ENABLES_CMD   ||
                        resp[2] != 0) {
                pr_warn("Invalid return from get global enables command, cannot enable the event buffer\n");
                rv = -EINVAL;
                goto out;
        }

        if (resp[3] & IPMI_BMC_EVT_MSG_BUFF) {
                /* buffer is already enabled, nothing to do. */
                smi_info->supports_event_msg_buff = true;
                goto out;
        }

        msg[0] = IPMI_NETFN_APP_REQUEST << 2;
        msg[1] = IPMI_SET_BMC_GLOBAL_ENABLES_CMD;
        msg[2] = resp[3] | IPMI_BMC_EVT_MSG_BUFF;
        smi_info->handlers->start_transaction(smi_info->si_sm, msg, 3);

        rv = wait_for_msg_done(smi_info);
        if (rv) {
                pr_warn("Error getting response from set global, enables command, the event buffer is not enabled\n");
                goto out;
        }

        resp_len = smi_info->handlers->get_result(smi_info->si_sm,
                                                  resp, IPMI_MAX_MSG_LENGTH);

        if (resp_len < 3 ||
                        resp[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2 ||
                        resp[1] != IPMI_SET_BMC_GLOBAL_ENABLES_CMD) {
                pr_warn("Invalid return from get global, enables command, not enable the event buffer\n");
                rv = -EINVAL;
                goto out;
        }

        if (resp[2] != 0)
                /*
                 * An error when setting the event buffer bit means
                 * that the event buffer is not supported.
                 */
                rv = -ENOENT;
        else
                smi_info->supports_event_msg_buff = true;

out:
        kfree(resp);
        return rv;
}

#define IPMI_SI_ATTR(name) \
static ssize_t name##_show(struct device *dev,                  \
                           struct device_attribute *attr,               \
                           char *buf)                                   \
{                                                                       \
        struct smi_info *smi_info = dev_get_drvdata(dev);               \
                                                                        \
        return snprintf(buf, 10, "%u\n", smi_get_stat(smi_info, name)); \
}                                                                       \
static DEVICE_ATTR(name, 0444, name##_show, NULL)

static ssize_t type_show(struct device *dev,
                         struct device_attribute *attr,
                         char *buf)
{
        struct smi_info *smi_info = dev_get_drvdata(dev);

        return snprintf(buf, 10, "%s\n", si_to_str[smi_info->io.si_type]);
}
static DEVICE_ATTR(type, 0444, type_show, NULL);

static ssize_t interrupts_enabled_show(struct device *dev,
                                       struct device_attribute *attr,
                                       char *buf)
{
        struct smi_info *smi_info = dev_get_drvdata(dev);
        int enabled = smi_info->io.irq && !smi_info->interrupt_disabled;

        return snprintf(buf, 10, "%d\n", enabled);
}
static DEVICE_ATTR(interrupts_enabled, 0444,
                   interrupts_enabled_show, NULL);

IPMI_SI_ATTR(short_timeouts);
IPMI_SI_ATTR(long_timeouts);
IPMI_SI_ATTR(idles);
IPMI_SI_ATTR(interrupts);
IPMI_SI_ATTR(attentions);
IPMI_SI_ATTR(flag_fetches);
IPMI_SI_ATTR(hosed_count);
IPMI_SI_ATTR(complete_transactions);
IPMI_SI_ATTR(events);
IPMI_SI_ATTR(watchdog_pretimeouts);
IPMI_SI_ATTR(incoming_messages);

static ssize_t params_show(struct device *dev,
                           struct device_attribute *attr,
                           char *buf)
{
        struct smi_info *smi_info = dev_get_drvdata(dev);

        return snprintf(buf, 200,
                        "%s,%s,0x%lx,rsp=%d,rsi=%d,rsh=%d,irq=%d,ipmb=%d\n",
                        si_to_str[smi_info->io.si_type],
                        addr_space_to_str[smi_info->io.addr_space],
                        smi_info->io.addr_data,
                        smi_info->io.regspacing,
                        smi_info->io.regsize,
                        smi_info->io.regshift,
                        smi_info->io.irq,
                        smi_info->io.slave_addr);
}
static DEVICE_ATTR(params, 0444, params_show, NULL);

static struct attribute *ipmi_si_dev_attrs[] = {
        &dev_attr_type.attr,
        &dev_attr_interrupts_enabled.attr,
        &dev_attr_short_timeouts.attr,
        &dev_attr_long_timeouts.attr,
        &dev_attr_idles.attr,
        &dev_attr_interrupts.attr,
        &dev_attr_attentions.attr,
        &dev_attr_flag_fetches.attr,
        &dev_attr_hosed_count.attr,
        &dev_attr_complete_transactions.attr,
        &dev_attr_events.attr,
        &dev_attr_watchdog_pretimeouts.attr,
        &dev_attr_incoming_messages.attr,
        &dev_attr_params.attr,
        NULL
};

static const struct attribute_group ipmi_si_dev_attr_group = {
        .attrs          = ipmi_si_dev_attrs,
};

/*
 * oem_data_avail_to_receive_msg_avail
 * @info - smi_info structure with msg_flags set
 *
 * Converts flags from OEM_DATA_AVAIL to RECEIVE_MSG_AVAIL
 * Returns 1 indicating need to re-run handle_flags().
 */
static int oem_data_avail_to_receive_msg_avail(struct smi_info *smi_info)
{
        smi_info->msg_flags = ((smi_info->msg_flags & ~OEM_DATA_AVAIL) |
                               RECEIVE_MSG_AVAIL);
        return 1;
}

/*
 * setup_dell_poweredge_oem_data_handler
 * @info - smi_info.device_id must be populated
 *
 * Systems that match, but have firmware version < 1.40 may assert
 * OEM0_DATA_AVAIL on their own, without being told via Set Flags that
 * it's safe to do so.  Such systems will de-assert OEM1_DATA_AVAIL
 * upon receipt of IPMI_GET_MSG_CMD, so we should treat these flags
 * as RECEIVE_MSG_AVAIL instead.
 *
 * As Dell has no plans to release IPMI 1.5 firmware that *ever*
 * assert the OEM[012] bits, and if it did, the driver would have to
 * change to handle that properly, we don't actually check for the
 * firmware version.
 * Device ID = 0x20                BMC on PowerEdge 8G servers
 * Device Revision = 0x80
 * Firmware Revision1 = 0x01       BMC version 1.40
 * Firmware Revision2 = 0x40       BCD encoded
 * IPMI Version = 0x51             IPMI 1.5
 * Manufacturer ID = A2 02 00      Dell IANA
 *
 * Additionally, PowerEdge systems with IPMI < 1.5 may also assert
 * OEM0_DATA_AVAIL and needs to be treated as RECEIVE_MSG_AVAIL.
 *
 */
#define DELL_POWEREDGE_8G_BMC_DEVICE_ID  0x20
#define DELL_POWEREDGE_8G_BMC_DEVICE_REV 0x80
#define DELL_POWEREDGE_8G_BMC_IPMI_VERSION 0x51
#define DELL_IANA_MFR_ID 0x0002a2
static void setup_dell_poweredge_oem_data_handler(struct smi_info *smi_info)
{
        struct ipmi_device_id *id = &smi_info->device_id;
        if (id->manufacturer_id == DELL_IANA_MFR_ID) {
                if (id->device_id       == DELL_POWEREDGE_8G_BMC_DEVICE_ID  &&
                    id->device_revision == DELL_POWEREDGE_8G_BMC_DEVICE_REV &&
                    id->ipmi_version   == DELL_POWEREDGE_8G_BMC_IPMI_VERSION) {
                        smi_info->oem_data_avail_handler =
                                oem_data_avail_to_receive_msg_avail;
                } else if (ipmi_version_major(id) < 1 ||
                           (ipmi_version_major(id) == 1 &&
                            ipmi_version_minor(id) < 5)) {
                        smi_info->oem_data_avail_handler =
                                oem_data_avail_to_receive_msg_avail;
                }
        }
}

#define CANNOT_RETURN_REQUESTED_LENGTH 0xCA
static void return_hosed_msg_badsize(struct smi_info *smi_info)
{
        struct ipmi_smi_msg *msg = smi_info->curr_msg;

        /* Make it a response */
        msg->rsp[0] = msg->data[0] | 4;
        msg->rsp[1] = msg->data[1];
        msg->rsp[2] = CANNOT_RETURN_REQUESTED_LENGTH;
        msg->rsp_size = 3;
        smi_info->curr_msg = NULL;
        deliver_recv_msg(smi_info, msg);
}

/*
 * dell_poweredge_bt_xaction_handler
 * @info - smi_info.device_id must be populated
 *
 * Dell PowerEdge servers with the BT interface (x6xx and 1750) will
 * not respond to a Get SDR command if the length of the data
 * requested is exactly 0x3A, which leads to command timeouts and no
 * data returned.  This intercepts such commands, and causes userspace
 * callers to try again with a different-sized buffer, which succeeds.
 */

#define STORAGE_NETFN 0x0A
#define STORAGE_CMD_GET_SDR 0x23
static int dell_poweredge_bt_xaction_handler(struct notifier_block *self,
                                             unsigned long unused,
                                             void *in)
{
        struct smi_info *smi_info = in;
        unsigned char *data = smi_info->curr_msg->data;
        unsigned int size   = smi_info->curr_msg->data_size;
        if (size >= 8 &&
            (data[0]>>2) == STORAGE_NETFN &&
            data[1] == STORAGE_CMD_GET_SDR &&
            data[7] == 0x3A) {
                return_hosed_msg_badsize(smi_info);
                return NOTIFY_STOP;
        }
        return NOTIFY_DONE;
}

static struct notifier_block dell_poweredge_bt_xaction_notifier = {
        .notifier_call  = dell_poweredge_bt_xaction_handler,
};

/*
 * setup_dell_poweredge_bt_xaction_handler
 * @info - smi_info.device_id must be filled in already
 *
 * Fills in smi_info.device_id.start_transaction_pre_hook
 * when we know what function to use there.
 */
static void
setup_dell_poweredge_bt_xaction_handler(struct smi_info *smi_info)
{
        struct ipmi_device_id *id = &smi_info->device_id;
        if (id->manufacturer_id == DELL_IANA_MFR_ID &&
            smi_info->io.si_type == SI_BT)
                register_xaction_notifier(&dell_poweredge_bt_xaction_notifier);
}

/*
 * setup_oem_data_handler
 * @info - smi_info.device_id must be filled in already
 *
 * Fills in smi_info.device_id.oem_data_available_handler
 * when we know what function to use there.
 */

static void setup_oem_data_handler(struct smi_info *smi_info)
{
        setup_dell_poweredge_oem_data_handler(smi_info);
}

static void setup_xaction_handlers(struct smi_info *smi_info)
{
        setup_dell_poweredge_bt_xaction_handler(smi_info);
}

static void check_for_broken_irqs(struct smi_info *smi_info)
{
        check_clr_rcv_irq(smi_info);
        check_set_rcv_irq(smi_info);
}

static inline void stop_timer_and_thread(struct smi_info *smi_info)
{
        if (smi_info->thread != NULL) {
                kthread_stop(smi_info->thread);
                smi_info->thread = NULL;
        }

        smi_info->timer_can_start = false;
        del_timer_sync(&smi_info->si_timer);
}

static struct smi_info *find_dup_si(struct smi_info *info)
{
        struct smi_info *e;

        list_for_each_entry(e, &smi_infos, link) {
                if (e->io.addr_space != info->io.addr_space)
                        continue;
                if (e->io.addr_data == info->io.addr_data) {
                        /*
                         * This is a cheap hack, ACPI doesn't have a defined
                         * slave address but SMBIOS does.  Pick it up from
                         * any source that has it available.
                         */
                        if (info->io.slave_addr && !e->io.slave_addr)
                                e->io.slave_addr = info->io.slave_addr;
                        return e;
                }
        }

        return NULL;
}

int ipmi_si_add_smi(struct si_sm_io *io)
{
        int rv = 0;
        struct smi_info *new_smi, *dup;

        /*
         * If the user gave us a hard-coded device at the same
         * address, they presumably want us to use it and not what is
         * in the firmware.
         */
        if (io->addr_source != SI_HARDCODED && io->addr_source != SI_HOTMOD &&
            ipmi_si_hardcode_match(io->addr_space, io->addr_data)) {
                dev_info(io->dev,
                         "Hard-coded device at this address already exists");
                return -ENODEV;
        }

        if (!io->io_setup) {
                if (io->addr_space == IPMI_IO_ADDR_SPACE) {
                        io->io_setup = ipmi_si_port_setup;
                } else if (io->addr_space == IPMI_MEM_ADDR_SPACE) {
                        io->io_setup = ipmi_si_mem_setup;
                } else {
                        return -EINVAL;
                }
        }

        new_smi = kzalloc(sizeof(*new_smi), GFP_KERNEL);
        if (!new_smi)
                return -ENOMEM;
        spin_lock_init(&new_smi->si_lock);

        new_smi->io = *io;

        mutex_lock(&smi_infos_lock);
        dup = find_dup_si(new_smi);
        if (dup) {
                if (new_smi->io.addr_source == SI_ACPI &&
                    dup->io.addr_source == SI_SMBIOS) {
                        /* We prefer ACPI over SMBIOS. */
                        dev_info(dup->io.dev,
                                 "Removing SMBIOS-specified %s state machine in favor of ACPI\n",
                                 si_to_str[new_smi->io.si_type]);
                        cleanup_one_si(dup);
                } else {
                        dev_info(new_smi->io.dev,
                                 "%s-specified %s state machine: duplicate\n",
                                 ipmi_addr_src_to_str(new_smi->io.addr_source),
                                 si_to_str[new_smi->io.si_type]);
                        rv = -EBUSY;
                        kfree(new_smi);
                        goto out_err;
                }
        }

        pr_info("Adding %s-specified %s state machine\n",
                ipmi_addr_src_to_str(new_smi->io.addr_source),
                si_to_str[new_smi->io.si_type]);

        list_add_tail(&new_smi->link, &smi_infos);

        if (initialized)
                rv = try_smi_init(new_smi);
out_err:
        mutex_unlock(&smi_infos_lock);
        return rv;
}

/*
 * Try to start up an interface.  Must be called with smi_infos_lock
 * held, primarily to keep smi_num consistent, we only one to do these
 * one at a time.
 */
static int try_smi_init(struct smi_info *new_smi)
{
        int rv = 0;
        int i;

        pr_info("Trying %s-specified %s state machine at %s address 0x%lx, slave address 0x%x, irq %d\n",
                ipmi_addr_src_to_str(new_smi->io.addr_source),
                si_to_str[new_smi->io.si_type],
                addr_space_to_str[new_smi->io.addr_space],
                new_smi->io.addr_data,
                new_smi->io.slave_addr, new_smi->io.irq);

        switch (new_smi->io.si_type) {
        case SI_KCS:
                new_smi->handlers = &kcs_smi_handlers;
                break;

        case SI_SMIC:
                new_smi->handlers = &smic_smi_handlers;
                break;

        case SI_BT:
                new_smi->handlers = &bt_smi_handlers;
                break;

        default:
                /* No support for anything else yet. */
                rv = -EIO;
                goto out_err;
        }

        new_smi->si_num = smi_num;

        /* Do this early so it's available for logs. */
        if (!new_smi->io.dev) {
                pr_err("IPMI interface added with no device\n");
                rv = -EIO;
                goto out_err;
        }

        /* Allocate the state machine's data and initialize it. */
        new_smi->si_sm = kmalloc(new_smi->handlers->size(), GFP_KERNEL);
        if (!new_smi->si_sm) {
                rv = -ENOMEM;
                goto out_err;
        }
        new_smi->io.io_size = new_smi->handlers->init_data(new_smi->si_sm,
                                                           &new_smi->io);

        /* Now that we know the I/O size, we can set up the I/O. */
        rv = new_smi->io.io_setup(&new_smi->io);
        if (rv) {
                dev_err(new_smi->io.dev, "Could not set up I/O space\n");
                goto out_err;
        }

        /* Do low-level detection first. */
        if (new_smi->handlers->detect(new_smi->si_sm)) {
                if (new_smi->io.addr_source)
                        dev_err(new_smi->io.dev,
                                "Interface detection failed\n");