// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * OPAL asynchronus Memory error handling support in PowerNV.
 *
 * Copyright 2013 IBM Corporation
 * Author: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/mm.h>
#include <linux/slab.h>

#include <asm/machdep.h>
#include <asm/opal.h>
#include <asm/cputable.h>

static int opal_mem_err_nb_init;
static LIST_HEAD(opal_memory_err_list);
static DEFINE_SPINLOCK(opal_mem_err_lock);

struct OpalMsgNode {
        struct list_head list;
        struct opal_msg msg;
};

static void handle_memory_error_event(struct OpalMemoryErrorData *merr_evt)
{
        uint64_t paddr_start, paddr_end;

        pr_debug("%s: Retrieved memory error event, type: 0x%x\n",
                  __func__, merr_evt->type);
        switch (merr_evt->type) {
        case OPAL_MEM_ERR_TYPE_RESILIENCE:
                paddr_start = be64_to_cpu(merr_evt->u.resilience.physical_address_start);
                paddr_end = be64_to_cpu(merr_evt->u.resilience.physical_address_end);
                break;
        case OPAL_MEM_ERR_TYPE_DYN_DALLOC:
                paddr_start = be64_to_cpu(merr_evt->u.dyn_dealloc.physical_address_start);
                paddr_end = be64_to_cpu(merr_evt->u.dyn_dealloc.physical_address_end);
                break;
        default:
                return;
        }

        for (; paddr_start < paddr_end; paddr_start += PAGE_SIZE) {
                memory_failure(paddr_start >> PAGE_SHIFT, 0);
        }
}

static void handle_memory_error(void)
{
        unsigned long flags;
        struct OpalMemoryErrorData *merr_evt;
        struct OpalMsgNode *msg_node;

        spin_lock_irqsave(&opal_mem_err_lock, flags);
        while (!list_empty(&opal_memory_err_list)) {
                 msg_node = list_entry(opal_memory_err_list.next,
                                           struct OpalMsgNode, list);
                list_del(&msg_node->list);
                spin_unlock_irqrestore(&opal_mem_err_lock, flags);

                merr_evt = (struct OpalMemoryErrorData *)
                                        &msg_node->msg.params[0];
                handle_memory_error_event(merr_evt);
                kfree(msg_node);
                spin_lock_irqsave(&opal_mem_err_lock, flags);
        }
        spin_unlock_irqrestore(&opal_mem_err_lock, flags);
}

static void mem_error_handler(struct work_struct *work)
{
        handle_memory_error();
}

static DECLARE_WORK(mem_error_work, mem_error_handler);

/*
 * opal_memory_err_event - notifier handler that queues up the opal message
 * to be processed later.
 */
static int opal_memory_err_event(struct notifier_block *nb,
                          unsigned long msg_type, void *msg)
{
        unsigned long flags;
        struct OpalMsgNode *msg_node;

        if (msg_type != OPAL_MSG_MEM_ERR)
                return 0;

        msg_node = kzalloc_obj(*msg_node, GFP_ATOMIC);
        if (!msg_node) {
                pr_err("MEMORY_ERROR: out of memory, Opal message event not"
                       "handled\n");
                return -ENOMEM;
        }
        memcpy(&msg_node->msg, msg, sizeof(msg_node->msg));

        spin_lock_irqsave(&opal_mem_err_lock, flags);
        list_add(&msg_node->list, &opal_memory_err_list);
        spin_unlock_irqrestore(&opal_mem_err_lock, flags);

        schedule_work(&mem_error_work);
        return 0;
}

static struct notifier_block opal_mem_err_nb = {
        .notifier_call  = opal_memory_err_event,
        .next           = NULL,
        .priority       = 0,
};

static int __init opal_mem_err_init(void)
{
        int ret;

        if (!opal_mem_err_nb_init) {
                ret = opal_message_notifier_register(
                                        OPAL_MSG_MEM_ERR, &opal_mem_err_nb);
                if (ret) {
                        pr_err("%s: Can't register OPAL event notifier (%d)\n",
                               __func__, ret);
                        return ret;
                }
                opal_mem_err_nb_init = 1;
        }
        return 0;
}
machine_device_initcall(powernv, opal_mem_err_init);