/*
 *  Common functions for kernel modules using Dell SMBIOS
 *
 *  Copyright (c) Red Hat <mjg@redhat.com>
 *  Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
 *  Copyright (c) 2014 Pali Rohár <pali.rohar@gmail.com>
 *
 *  Based on documentation in the libsmbios package:
 *  Copyright (C) 2005-2014 Dell Inc.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/dmi.h>
#include <linux/err.h>
#include <linux/gfp.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/io.h>
#include "../../firmware/dcdbas.h"
#include "dell-smbios.h"

struct calling_interface_structure {
        struct dmi_header header;
        u16 cmdIOAddress;
        u8 cmdIOCode;
        u32 supportedCmds;
        struct calling_interface_token tokens[];
} __packed;

static struct calling_interface_buffer *buffer;
static DEFINE_MUTEX(buffer_mutex);

static int da_command_address;
static int da_command_code;
static int da_num_tokens;
static struct calling_interface_token *da_tokens;

int dell_smbios_error(int value)
{
        switch (value) {
        case 0: /* Completed successfully */
                return 0;
        case -1: /* Completed with error */
                return -EIO;
        case -2: /* Function not supported */
                return -ENXIO;
        default: /* Unknown error */
                return -EINVAL;
        }
}
EXPORT_SYMBOL_GPL(dell_smbios_error);

struct calling_interface_buffer *dell_smbios_get_buffer(void)
{
        mutex_lock(&buffer_mutex);
        dell_smbios_clear_buffer();
        return buffer;
}
EXPORT_SYMBOL_GPL(dell_smbios_get_buffer);

void dell_smbios_clear_buffer(void)
{
        memset(buffer, 0, sizeof(struct calling_interface_buffer));
}
EXPORT_SYMBOL_GPL(dell_smbios_clear_buffer);

void dell_smbios_release_buffer(void)
{
        mutex_unlock(&buffer_mutex);
}
EXPORT_SYMBOL_GPL(dell_smbios_release_buffer);

void dell_smbios_send_request(int class, int select)
{
        struct smi_cmd command;

        command.magic = SMI_CMD_MAGIC;
        command.command_address = da_command_address;
        command.command_code = da_command_code;
        command.ebx = virt_to_phys(buffer);
        command.ecx = 0x42534931;

        buffer->class = class;
        buffer->select = select;

        dcdbas_smi_request(&command);
}
EXPORT_SYMBOL_GPL(dell_smbios_send_request);

struct calling_interface_token *dell_smbios_find_token(int tokenid)
{
        int i;

        for (i = 0; i < da_num_tokens; i++) {
                if (da_tokens[i].tokenID == tokenid)
                        return &da_tokens[i];
        }

        return NULL;
}
EXPORT_SYMBOL_GPL(dell_smbios_find_token);

static BLOCKING_NOTIFIER_HEAD(dell_laptop_chain_head);

int dell_laptop_register_notifier(struct notifier_block *nb)
{
        return blocking_notifier_chain_register(&dell_laptop_chain_head, nb);
}
EXPORT_SYMBOL_GPL(dell_laptop_register_notifier);

int dell_laptop_unregister_notifier(struct notifier_block *nb)
{
        return blocking_notifier_chain_unregister(&dell_laptop_chain_head, nb);
}
EXPORT_SYMBOL_GPL(dell_laptop_unregister_notifier);

void dell_laptop_call_notifier(unsigned long action, void *data)
{
        blocking_notifier_call_chain(&dell_laptop_chain_head, action, data);
}
EXPORT_SYMBOL_GPL(dell_laptop_call_notifier);

static void __init parse_da_table(const struct dmi_header *dm)
{
        /* Final token is a terminator, so we don't want to copy it */
        int tokens = (dm->length-11)/sizeof(struct calling_interface_token)-1;
        struct calling_interface_token *new_da_tokens;
        struct calling_interface_structure *table =
                container_of(dm, struct calling_interface_structure, header);

        /* 4 bytes of table header, plus 7 bytes of Dell header, plus at least
           6 bytes of entry */

        if (dm->length < 17)
                return;

        da_command_address = table->cmdIOAddress;
        da_command_code = table->cmdIOCode;

        new_da_tokens = krealloc(da_tokens, (da_num_tokens + tokens) *
                                 sizeof(struct calling_interface_token),
                                 GFP_KERNEL);

        if (!new_da_tokens)
                return;
        da_tokens = new_da_tokens;

        memcpy(da_tokens+da_num_tokens, table->tokens,
               sizeof(struct calling_interface_token) * tokens);

        da_num_tokens += tokens;
}

static void __init find_tokens(const struct dmi_header *dm, void *dummy)
{
        switch (dm->type) {
        case 0xd4: /* Indexed IO */
        case 0xd5: /* Protected Area Type 1 */
        case 0xd6: /* Protected Area Type 2 */
                break;
        case 0xda: /* Calling interface */
                parse_da_table(dm);
                break;
        }
}

static int __init dell_smbios_init(void)
{
        int ret;

        dmi_walk(find_tokens, NULL);

        if (!da_tokens)  {
                pr_info("Unable to find dmi tokens\n");
                return -ENODEV;
        }

        /*
         * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
         * is passed to SMI handler.
         */
        buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
        if (!buffer) {
                ret = -ENOMEM;
                goto fail_buffer;
        }

        return 0;

fail_buffer:
        kfree(da_tokens);
        return ret;
}

static void __exit dell_smbios_exit(void)
{
        kfree(da_tokens);
        free_page((unsigned long)buffer);
}

subsys_initcall(dell_smbios_init);
module_exit(dell_smbios_exit);

MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
MODULE_LICENSE("GPL");