/*
 * PowerNV OPAL high level interfaces
 *
 * Copyright 2011 IBM Corp.
 *
 * 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.
 */

#undef DEBUG

#include <linux/types.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/of_platform.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/kobject.h>
#include <linux/delay.h>
#include <asm/opal.h>
#include <asm/firmware.h>
#include <asm/mce.h>

#include "powernv.h"

/* /sys/firmware/opal */
struct kobject *opal_kobj;

struct opal {
        u64 base;
        u64 entry;
} opal;

static struct device_node *opal_node;
static DEFINE_SPINLOCK(opal_write_lock);
extern u64 opal_mc_secondary_handler[];
static unsigned int *opal_irqs;
static unsigned int opal_irq_count;
static ATOMIC_NOTIFIER_HEAD(opal_notifier_head);
static struct atomic_notifier_head opal_msg_notifier_head[OPAL_MSG_TYPE_MAX];
static DEFINE_SPINLOCK(opal_notifier_lock);
static uint64_t last_notified_mask = 0x0ul;
static atomic_t opal_notifier_hold = ATOMIC_INIT(0);

int __init early_init_dt_scan_opal(unsigned long node,
                                   const char *uname, int depth, void *data)
{
        const void *basep, *entryp;
        unsigned long basesz, entrysz;

        if (depth != 1 || strcmp(uname, "ibm,opal") != 0)
                return 0;

        basep  = of_get_flat_dt_prop(node, "opal-base-address", &basesz);
        entryp = of_get_flat_dt_prop(node, "opal-entry-address", &entrysz);

        if (!basep || !entryp)
                return 1;

        opal.base = of_read_number(basep, basesz/4);
        opal.entry = of_read_number(entryp, entrysz/4);

        pr_debug("OPAL Base  = 0x%llx (basep=%p basesz=%ld)\n",
                 opal.base, basep, basesz);
        pr_debug("OPAL Entry = 0x%llx (entryp=%p basesz=%ld)\n",
                 opal.entry, entryp, entrysz);

        powerpc_firmware_features |= FW_FEATURE_OPAL;
        if (of_flat_dt_is_compatible(node, "ibm,opal-v3")) {
                powerpc_firmware_features |= FW_FEATURE_OPALv2;
                powerpc_firmware_features |= FW_FEATURE_OPALv3;
                printk("OPAL V3 detected !\n");
        } else if (of_flat_dt_is_compatible(node, "ibm,opal-v2")) {
                powerpc_firmware_features |= FW_FEATURE_OPALv2;
                printk("OPAL V2 detected !\n");
        } else {
                printk("OPAL V1 detected !\n");
        }

        return 1;
}

static int __init opal_register_exception_handlers(void)
{
#ifdef __BIG_ENDIAN__
        u64 glue;

        if (!(powerpc_firmware_features & FW_FEATURE_OPAL))
                return -ENODEV;

        /* Hookup some exception handlers except machine check. We use the
         * fwnmi area at 0x7000 to provide the glue space to OPAL
         */
        glue = 0x7000;
        opal_register_exception_handler(OPAL_HYPERVISOR_MAINTENANCE_HANDLER,
                                        0, glue);
        glue += 128;
        opal_register_exception_handler(OPAL_SOFTPATCH_HANDLER, 0, glue);
#endif

        return 0;
}

early_initcall(opal_register_exception_handlers);

int opal_notifier_register(struct notifier_block *nb)
{
        if (!nb) {
                pr_warning("%s: Invalid argument (%p)\n",
                           __func__, nb);
                return -EINVAL;
        }

        atomic_notifier_chain_register(&opal_notifier_head, nb);
        return 0;
}

static void opal_do_notifier(uint64_t events)
{
        unsigned long flags;
        uint64_t changed_mask;

        if (atomic_read(&opal_notifier_hold))
                return;

        spin_lock_irqsave(&opal_notifier_lock, flags);
        changed_mask = last_notified_mask ^ events;
        last_notified_mask = events;
        spin_unlock_irqrestore(&opal_notifier_lock, flags);

        /*
         * We feed with the event bits and changed bits for
         * enough information to the callback.
         */
        atomic_notifier_call_chain(&opal_notifier_head,
                                   events, (void *)changed_mask);
}

void opal_notifier_update_evt(uint64_t evt_mask,
                              uint64_t evt_val)
{
        unsigned long flags;

        spin_lock_irqsave(&opal_notifier_lock, flags);
        last_notified_mask &= ~evt_mask;
        last_notified_mask |= evt_val;
        spin_unlock_irqrestore(&opal_notifier_lock, flags);
}

void opal_notifier_enable(void)
{
        int64_t rc;
        uint64_t evt = 0;

        atomic_set(&opal_notifier_hold, 0);

        /* Process pending events */
        rc = opal_poll_events(&evt);
        if (rc == OPAL_SUCCESS && evt)
                opal_do_notifier(evt);
}

void opal_notifier_disable(void)
{
        atomic_set(&opal_notifier_hold, 1);
}

/*
 * Opal message notifier based on message type. Allow subscribers to get
 * notified for specific messgae type.
 */
int opal_message_notifier_register(enum OpalMessageType msg_type,
                                        struct notifier_block *nb)
{
        if (!nb) {
                pr_warning("%s: Invalid argument (%p)\n",
                           __func__, nb);
                return -EINVAL;
        }
        if (msg_type > OPAL_MSG_TYPE_MAX) {
                pr_warning("%s: Invalid message type argument (%d)\n",
                           __func__, msg_type);
                return -EINVAL;
        }
        return atomic_notifier_chain_register(
                                &opal_msg_notifier_head[msg_type], nb);
}

static void opal_message_do_notify(uint32_t msg_type, void *msg)
{
        /* notify subscribers */
        atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type],
                                        msg_type, msg);
}

static void opal_handle_message(void)
{
        s64 ret;
        /*
         * TODO: pre-allocate a message buffer depending on opal-msg-size
         * value in /proc/device-tree.
         */
        static struct opal_msg msg;

        ret = opal_get_msg(__pa(&msg), sizeof(msg));
        /* No opal message pending. */
        if (ret == OPAL_RESOURCE)
                return;

        /* check for errors. */
        if (ret) {
                pr_warning("%s: Failed to retrive opal message, err=%lld\n",
                                __func__, ret);
                return;
        }

        /* Sanity check */
        if (msg.msg_type > OPAL_MSG_TYPE_MAX) {
                pr_warning("%s: Unknown message type: %u\n",
                                __func__, msg.msg_type);
                return;
        }
        opal_message_do_notify(msg.msg_type, (void *)&msg);
}

static int opal_message_notify(struct notifier_block *nb,
                          unsigned long events, void *change)
{
        if (events & OPAL_EVENT_MSG_PENDING)
                opal_handle_message();
        return 0;
}

static struct notifier_block opal_message_nb = {
        .notifier_call  = opal_message_notify,
        .next           = NULL,
        .priority       = 0,
};

static int __init opal_message_init(void)
{
        int ret, i;

        for (i = 0; i < OPAL_MSG_TYPE_MAX; i++)
                ATOMIC_INIT_NOTIFIER_HEAD(&opal_msg_notifier_head[i]);

        ret = opal_notifier_register(&opal_message_nb);
        if (ret) {
                pr_err("%s: Can't register OPAL event notifier (%d)\n",
                       __func__, ret);
                return ret;
        }
        return 0;
}
early_initcall(opal_message_init);

int opal_get_chars(uint32_t vtermno, char *buf, int count)
{
        s64 rc;
        __be64 evt, len;

        if (!opal.entry)
                return -ENODEV;
        opal_poll_events(&evt);
        if ((be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_INPUT) == 0)
                return 0;
        len = cpu_to_be64(count);
        rc = opal_console_read(vtermno, &len, buf);     
        if (rc == OPAL_SUCCESS)
                return be64_to_cpu(len);
        return 0;
}

int opal_put_chars(uint32_t vtermno, const char *data, int total_len)
{
        int written = 0;
        __be64 olen;
        s64 len, rc;
        unsigned long flags;
        __be64 evt;

        if (!opal.entry)
                return -ENODEV;

        /* We want put_chars to be atomic to avoid mangling of hvsi
         * packets. To do that, we first test for room and return
         * -EAGAIN if there isn't enough.
         *
         * Unfortunately, opal_console_write_buffer_space() doesn't
         * appear to work on opal v1, so we just assume there is
         * enough room and be done with it
         */
        spin_lock_irqsave(&opal_write_lock, flags);
        if (firmware_has_feature(FW_FEATURE_OPALv2)) {
                rc = opal_console_write_buffer_space(vtermno, &olen);
                len = be64_to_cpu(olen);
                if (rc || len < total_len) {
                        spin_unlock_irqrestore(&opal_write_lock, flags);
                        /* Closed -> drop characters */
                        if (rc)
                                return total_len;
                        opal_poll_events(NULL);
                        return -EAGAIN;
                }
        }

        /* We still try to handle partial completions, though they
         * should no longer happen.
         */
        rc = OPAL_BUSY;
        while(total_len > 0 && (rc == OPAL_BUSY ||
                                rc == OPAL_BUSY_EVENT || rc == OPAL_SUCCESS)) {
                olen = cpu_to_be64(total_len);
                rc = opal_console_write(vtermno, &olen, data);
                len = be64_to_cpu(olen);

                /* Closed or other error drop */
                if (rc != OPAL_SUCCESS && rc != OPAL_BUSY &&
                    rc != OPAL_BUSY_EVENT) {
                        written = total_len;
                        break;
                }
                if (rc == OPAL_SUCCESS) {
                        total_len -= len;
                        data += len;
                        written += len;
                }
                /* This is a bit nasty but we need that for the console to
                 * flush when there aren't any interrupts. We will clean
                 * things a bit later to limit that to synchronous path
                 * such as the kernel console and xmon/udbg
                 */
                do
                        opal_poll_events(&evt);
                while(rc == OPAL_SUCCESS &&
                        (be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_OUTPUT));
        }
        spin_unlock_irqrestore(&opal_write_lock, flags);
        return written;
}

static int opal_recover_mce(struct pt_regs *regs,
                                        struct machine_check_event *evt)
{
        int recovered = 0;
        uint64_t ea = get_mce_fault_addr(evt);

        if (!(regs->msr & MSR_RI)) {
                /* If MSR_RI isn't set, we cannot recover */
                recovered = 0;
        } else if (evt->disposition == MCE_DISPOSITION_RECOVERED) {
                /* Platform corrected itself */
                recovered = 1;
        } else if (ea && !is_kernel_addr(ea)) {
                /*
                 * Faulting address is not in kernel text. We should be fine.
                 * We need to find which process uses this address.
                 * For now, kill the task if we have received exception when
                 * in userspace.
                 *
                 * TODO: Queue up this address for hwpoisioning later.
                 */
                if (user_mode(regs) && !is_global_init(current)) {
                        _exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
                        recovered = 1;
                } else
                        recovered = 0;
        } else if (user_mode(regs) && !is_global_init(current) &&
                evt->severity == MCE_SEV_ERROR_SYNC) {
                /*
                 * If we have received a synchronous error when in userspace
                 * kill the task.
                 */
                _exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
                recovered = 1;
        }
        return recovered;
}

int opal_machine_check(struct pt_regs *regs)
{
        struct machine_check_event evt;

        if (!get_mce_event(&evt, MCE_EVENT_RELEASE))
                return 0;

        /* Print things out */
        if (evt.version != MCE_V1) {
                pr_err("Machine Check Exception, Unknown event version %d !\n",
                       evt.version);
                return 0;
        }
        machine_check_print_event_info(&evt);

        if (opal_recover_mce(regs, &evt))
                return 1;
        return 0;
}

static irqreturn_t opal_interrupt(int irq, void *data)
{
        __be64 events;

        opal_handle_interrupt(virq_to_hw(irq), &events);

        opal_do_notifier(events);

        return IRQ_HANDLED;
}

static int opal_sysfs_init(void)
{
        opal_kobj = kobject_create_and_add("opal", firmware_kobj);
        if (!opal_kobj) {
                pr_warn("kobject_create_and_add opal failed\n");
                return -ENOMEM;
        }

        return 0;
}

static int __init opal_init(void)
{
        struct device_node *np, *consoles;
        const __be32 *irqs;
        int rc, i, irqlen;

        opal_node = of_find_node_by_path("/ibm,opal");
        if (!opal_node) {
                pr_warn("opal: Node not found\n");
                return -ENODEV;
        }

        /* Register OPAL consoles if any ports */
        if (firmware_has_feature(FW_FEATURE_OPALv2))
                consoles = of_find_node_by_path("/ibm,opal/consoles");
        else
                consoles = of_node_get(opal_node);
        if (consoles) {
                for_each_child_of_node(consoles, np) {
                        if (strcmp(np->name, "serial"))
                                continue;
                        of_platform_device_create(np, NULL, NULL);
                }
                of_node_put(consoles);
        }

        /* Find all OPAL interrupts and request them */
        irqs = of_get_property(opal_node, "opal-interrupts", &irqlen);
        pr_debug("opal: Found %d interrupts reserved for OPAL\n",
                 irqs ? (irqlen / 4) : 0);
        opal_irq_count = irqlen / 4;
        opal_irqs = kzalloc(opal_irq_count * sizeof(unsigned int), GFP_KERNEL);
        for (i = 0; irqs && i < (irqlen / 4); i++, irqs++) {
                unsigned int hwirq = be32_to_cpup(irqs);
                unsigned int irq = irq_create_mapping(NULL, hwirq);
                if (irq == NO_IRQ) {
                        pr_warning("opal: Failed to map irq 0x%x\n", hwirq);
                        continue;
                }
                rc = request_irq(irq, opal_interrupt, 0, "opal", NULL);
                if (rc)
                        pr_warning("opal: Error %d requesting irq %d"
                                   " (0x%x)\n", rc, irq, hwirq);
                opal_irqs[i] = irq;
        }

        /* Create "opal" kobject under /sys/firmware */
        rc = opal_sysfs_init();
        if (rc == 0) {
                /* Setup code update interface */
                opal_flash_init();
        }

        return 0;
}
subsys_initcall(opal_init);

void opal_shutdown(void)
{
        unsigned int i;
        long rc = OPAL_BUSY;

        /* First free interrupts, which will also mask them */
        for (i = 0; i < opal_irq_count; i++) {
                if (opal_irqs[i])
                        free_irq(opal_irqs[i], NULL);
                opal_irqs[i] = 0;
        }

        /*
         * Then sync with OPAL which ensure anything that can
         * potentially write to our memory has completed such
         * as an ongoing dump retrieval
         */
        while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
                rc = opal_sync_host_reboot();
                if (rc == OPAL_BUSY)
                        opal_poll_events(NULL);
                else
                        mdelay(10);
        }
}