/*
 *  WMI methods for use with dell-smbios
 *
 *  Copyright (c) 2017 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.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/dmi.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/wmi.h>
#include "dell-smbios.h"
#include "dell-wmi-descriptor.h"

static DEFINE_MUTEX(call_mutex);
static DEFINE_MUTEX(list_mutex);
static int wmi_supported;

struct misc_bios_flags_structure {
        struct dmi_header header;
        u16 flags0;
} __packed;
#define FLAG_HAS_ACPI_WMI 0x02

#define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"

struct wmi_smbios_priv {
        struct dell_wmi_smbios_buffer *buf;
        struct list_head list;
        struct wmi_device *wdev;
        struct device *child;
        u32 req_buf_size;
};
static LIST_HEAD(wmi_list);

static inline struct wmi_smbios_priv *get_first_smbios_priv(void)
{
        return list_first_entry_or_null(&wmi_list,
                                        struct wmi_smbios_priv,
                                        list);
}

static int run_smbios_call(struct wmi_device *wdev)
{
        struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
        struct wmi_smbios_priv *priv;
        struct acpi_buffer input;
        union acpi_object *obj;
        acpi_status status;

        priv = dev_get_drvdata(&wdev->dev);
        input.length = priv->req_buf_size - sizeof(u64);
        input.pointer = &priv->buf->std;

        dev_dbg(&wdev->dev, "evaluating: %u/%u [%x,%x,%x,%x]\n",
                priv->buf->std.cmd_class, priv->buf->std.cmd_select,
                priv->buf->std.input[0], priv->buf->std.input[1],
                priv->buf->std.input[2], priv->buf->std.input[3]);

        status = wmidev_evaluate_method(wdev, 0, 1, &input, &output);
        if (ACPI_FAILURE(status))
                return -EIO;
        obj = (union acpi_object *)output.pointer;
        if (obj->type != ACPI_TYPE_BUFFER) {
                dev_dbg(&wdev->dev, "received type: %d\n", obj->type);
                if (obj->type == ACPI_TYPE_INTEGER)
                        dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n",
                                obj->integer.value);
                return -EIO;
        }
        memcpy(&priv->buf->std, obj->buffer.pointer, obj->buffer.length);
        dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n",
                priv->buf->std.output[0], priv->buf->std.output[1],
                priv->buf->std.output[2], priv->buf->std.output[3]);
        kfree(output.pointer);

        return 0;
}

static int dell_smbios_wmi_call(struct calling_interface_buffer *buffer)
{
        struct wmi_smbios_priv *priv;
        size_t difference;
        size_t size;
        int ret;

        mutex_lock(&call_mutex);
        priv = get_first_smbios_priv();
        if (!priv) {
                ret = -ENODEV;
                goto out_wmi_call;
        }

        size = sizeof(struct calling_interface_buffer);
        difference = priv->req_buf_size - sizeof(u64) - size;

        memset(&priv->buf->ext, 0, difference);
        memcpy(&priv->buf->std, buffer, size);
        ret = run_smbios_call(priv->wdev);
        memcpy(buffer, &priv->buf->std, size);
out_wmi_call:
        mutex_unlock(&call_mutex);

        return ret;
}

static long dell_smbios_wmi_filter(struct wmi_device *wdev, unsigned int cmd,
                                   struct wmi_ioctl_buffer *arg)
{
        struct wmi_smbios_priv *priv;
        int ret = 0;

        switch (cmd) {
        case DELL_WMI_SMBIOS_CMD:
                mutex_lock(&call_mutex);
                priv = dev_get_drvdata(&wdev->dev);
                if (!priv) {
                        ret = -ENODEV;
                        goto fail_smbios_cmd;
                }
                memcpy(priv->buf, arg, priv->req_buf_size);
                if (dell_smbios_call_filter(&wdev->dev, &priv->buf->std)) {
                        dev_err(&wdev->dev, "Invalid call %d/%d:%8x\n",
                                priv->buf->std.cmd_class,
                                priv->buf->std.cmd_select,
                                priv->buf->std.input[0]);
                        ret = -EFAULT;
                        goto fail_smbios_cmd;
                }
                ret = run_smbios_call(priv->wdev);
                if (ret)
                        goto fail_smbios_cmd;
                memcpy(arg, priv->buf, priv->req_buf_size);
fail_smbios_cmd:
                mutex_unlock(&call_mutex);
                break;
        default:
                ret = -ENOIOCTLCMD;
        }
        return ret;
}

static int dell_smbios_wmi_probe(struct wmi_device *wdev)
{
        struct wmi_driver *wdriver =
                container_of(wdev->dev.driver, struct wmi_driver, driver);
        struct wmi_smbios_priv *priv;
        u32 hotfix;
        int count;
        int ret;

        ret = dell_wmi_get_descriptor_valid();
        if (ret)
                return ret;

        priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv),
                            GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        /* WMI buffer size will be either 4k or 32k depending on machine */
        if (!dell_wmi_get_size(&priv->req_buf_size))
                return -EPROBE_DEFER;

        /* some SMBIOS calls fail unless BIOS contains hotfix */
        if (!dell_wmi_get_hotfix(&hotfix))
                return -EPROBE_DEFER;
        if (!hotfix) {
                dev_warn(&wdev->dev,
                        "WMI SMBIOS userspace interface not supported(%u), try upgrading to a newer BIOS\n",
                        hotfix);
                wdriver->filter_callback = NULL;
        }

        /* add in the length object we will use internally with ioctl */
        priv->req_buf_size += sizeof(u64);
        ret = set_required_buffer_size(wdev, priv->req_buf_size);
        if (ret)
                return ret;

        count = get_order(priv->req_buf_size);
        priv->buf = (void *)__get_free_pages(GFP_KERNEL, count);
        if (!priv->buf)
                return -ENOMEM;

        /* ID is used by dell-smbios to set priority of drivers */
        wdev->dev.id = 1;
        ret = dell_smbios_register_device(&wdev->dev, &dell_smbios_wmi_call);
        if (ret)
                goto fail_register;

        priv->wdev = wdev;
        dev_set_drvdata(&wdev->dev, priv);
        mutex_lock(&list_mutex);
        list_add_tail(&priv->list, &wmi_list);
        mutex_unlock(&list_mutex);

        return 0;

fail_register:
        free_pages((unsigned long)priv->buf, count);
        return ret;
}

static int dell_smbios_wmi_remove(struct wmi_device *wdev)
{
        struct wmi_smbios_priv *priv = dev_get_drvdata(&wdev->dev);
        int count;

        mutex_lock(&call_mutex);
        mutex_lock(&list_mutex);
        list_del(&priv->list);
        mutex_unlock(&list_mutex);
        dell_smbios_unregister_device(&wdev->dev);
        count = get_order(priv->req_buf_size);
        free_pages((unsigned long)priv->buf, count);
        mutex_unlock(&call_mutex);
        return 0;
}

static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
        { .guid_string = DELL_WMI_SMBIOS_GUID },
        { },
};

static void parse_b1_table(const struct dmi_header *dm)
{
        struct misc_bios_flags_structure *flags =
        container_of(dm, struct misc_bios_flags_structure, header);

        /* 4 bytes header, 8 bytes flags */
        if (dm->length < 12)
                return;
        if (dm->handle != 0xb100)
                return;
        if ((flags->flags0 & FLAG_HAS_ACPI_WMI))
                wmi_supported = 1;
}

static void find_b1(const struct dmi_header *dm, void *dummy)
{
        switch (dm->type) {
        case 0xb1: /* misc bios flags */
                parse_b1_table(dm);
                break;
        }
}

static struct wmi_driver dell_smbios_wmi_driver = {
        .driver = {
                .name = "dell-smbios",
        },
        .probe = dell_smbios_wmi_probe,
        .remove = dell_smbios_wmi_remove,
        .id_table = dell_smbios_wmi_id_table,
        .filter_callback = dell_smbios_wmi_filter,
};

int init_dell_smbios_wmi(void)
{
        dmi_walk(find_b1, NULL);

        if (!wmi_supported)
                return -ENODEV;

        return wmi_driver_register(&dell_smbios_wmi_driver);
}

void exit_dell_smbios_wmi(void)
{
        wmi_driver_unregister(&dell_smbios_wmi_driver);
}

MODULE_ALIAS("wmi:" DELL_WMI_SMBIOS_GUID);