// SPDX-License-Identifier: GPL-2.0+
/*
 * IUCV special message driver
 *
 * Copyright IBM Corp. 2003, 2009
 *
 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

#include <linux/export.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <net/iucv/iucv.h>
#include <asm/machine.h>
#include <asm/cpcmd.h>
#include <asm/ebcdic.h>
#include "smsgiucv.h"

struct smsg_callback {
        struct list_head list;
        const char *prefix;
        int len;
        void (*callback)(const char *from, char *str);
};

MODULE_AUTHOR
   ("(C) 2003 IBM Corporation by Martin Schwidefsky (schwidefsky@de.ibm.com)");
MODULE_DESCRIPTION ("Linux for S/390 IUCV special message driver");

static struct iucv_path *smsg_path;

static DEFINE_SPINLOCK(smsg_list_lock);
static LIST_HEAD(smsg_list);

static int smsg_path_pending(struct iucv_path *, u8 *, u8 *);
static void smsg_message_pending(struct iucv_path *, struct iucv_message *);

static struct iucv_handler smsg_handler = {
        .path_pending    = smsg_path_pending,
        .message_pending = smsg_message_pending,
};

static int smsg_path_pending(struct iucv_path *path, u8 *ipvmid, u8 *ipuser)
{
        if (strncmp(ipvmid, "*MSG    ", 8) != 0)
                return -EINVAL;
        /* Path pending from *MSG. */
        return iucv_path_accept(path, &smsg_handler, "SMSGIUCV        ", NULL);
}

static void smsg_message_pending(struct iucv_path *path,
                                 struct iucv_message *msg)
{
        struct smsg_callback *cb;
        unsigned char *buffer;
        unsigned char sender[9];
        int rc, i;

        buffer = kmalloc(msg->length + 1, GFP_ATOMIC | GFP_DMA);
        if (!buffer) {
                iucv_message_reject(path, msg);
                return;
        }
        rc = iucv_message_receive(path, msg, 0, buffer, msg->length, NULL);
        if (rc == 0) {
                buffer[msg->length] = 0;
                EBCASC(buffer, msg->length);
                memcpy(sender, buffer, 8);
                sender[8] = 0;
                /* Remove trailing whitespace from the sender name. */
                for (i = 7; i >= 0; i--) {
                        if (sender[i] != ' ' && sender[i] != '\t')
                                break;
                        sender[i] = 0;
                }
                spin_lock(&smsg_list_lock);
                list_for_each_entry(cb, &smsg_list, list)
                        if (strncmp(buffer + 8, cb->prefix, cb->len) == 0) {
                                cb->callback(sender, buffer + 8);
                                break;
                        }
                spin_unlock(&smsg_list_lock);
        }
        kfree(buffer);
}

int smsg_register_callback(const char *prefix,
                           void (*callback)(const char *from, char *str))
{
        struct smsg_callback *cb;

        cb = kmalloc_obj(struct smsg_callback);
        if (!cb)
                return -ENOMEM;
        cb->prefix = prefix;
        cb->len = strlen(prefix);
        cb->callback = callback;
        spin_lock_bh(&smsg_list_lock);
        list_add_tail(&cb->list, &smsg_list);
        spin_unlock_bh(&smsg_list_lock);
        return 0;
}

void smsg_unregister_callback(const char *prefix,
                              void (*callback)(const char *from,
                                               char *str))
{
        struct smsg_callback *cb, *tmp;

        spin_lock_bh(&smsg_list_lock);
        cb = NULL;
        list_for_each_entry(tmp, &smsg_list, list)
                if (tmp->callback == callback &&
                    strcmp(tmp->prefix, prefix) == 0) {
                        cb = tmp;
                        list_del(&cb->list);
                        break;
                }
        spin_unlock_bh(&smsg_list_lock);
        kfree(cb);
}

static struct device_driver smsg_driver = {
        .owner = THIS_MODULE,
        .name = SMSGIUCV_DRV_NAME,
        .bus  = &iucv_bus,
};

static void __exit smsg_exit(void)
{
        cpcmd("SET SMSG OFF", NULL, 0, NULL);
        iucv_unregister(&smsg_handler, 1);
        driver_unregister(&smsg_driver);
}

static int __init smsg_init(void)
{
        int rc;

        if (!machine_is_vm()) {
                rc = -EPROTONOSUPPORT;
                goto out;
        }
        rc = driver_register(&smsg_driver);
        if (rc != 0)
                goto out;
        rc = iucv_register(&smsg_handler, 1);
        if (rc)
                goto out_driver;
        smsg_path = iucv_path_alloc(255, 0, GFP_KERNEL);
        if (!smsg_path) {
                rc = -ENOMEM;
                goto out_register;
        }
        rc = iucv_path_connect(smsg_path, &smsg_handler, "*MSG    ",
                               NULL, NULL, NULL);
        if (rc)
                goto out_free_path;

        cpcmd("SET SMSG IUCV", NULL, 0, NULL);
        return 0;

out_free_path:
        iucv_path_free(smsg_path);
        smsg_path = NULL;
out_register:
        iucv_unregister(&smsg_handler, 1);
out_driver:
        driver_unregister(&smsg_driver);
out:
        return rc;
}

module_init(smsg_init);
module_exit(smsg_exit);
MODULE_LICENSE("GPL");

EXPORT_SYMBOL(smsg_register_callback);
EXPORT_SYMBOL(smsg_unregister_callback);