// SPDX-License-Identifier: GPL-2.0-only
/*
 *  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@kernel.org>
 *
 *  Based on documentation in the libsmbios package:
 *  Copyright (C) 2005-2014 Dell Inc.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/capability.h>
#include <linux/dmi.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include "dell-smbios.h"

static u32 da_supported_commands;
static int da_num_tokens;
static struct platform_device *platform_device;
static struct calling_interface_token *da_tokens;
static struct device_attribute *token_location_attrs;
static struct device_attribute *token_value_attrs;
static struct attribute **token_attrs;
static DEFINE_MUTEX(smbios_mutex);

struct smbios_device {
        struct list_head list;
        struct device *device;
        int (*call_fn)(struct calling_interface_buffer *arg);
};

struct smbios_call {
        u32 need_capability;
        int cmd_class;
        int cmd_select;
};

/* calls that are whitelisted for given capabilities */
static struct smbios_call call_whitelist[] = {
        /* generally tokens are allowed, but may be further filtered or
         * restricted by token blacklist or whitelist
         */
        {CAP_SYS_ADMIN, CLASS_TOKEN_READ,       SELECT_TOKEN_STD},
        {CAP_SYS_ADMIN, CLASS_TOKEN_READ,       SELECT_TOKEN_AC},
        {CAP_SYS_ADMIN, CLASS_TOKEN_READ,       SELECT_TOKEN_BAT},
        {CAP_SYS_ADMIN, CLASS_TOKEN_WRITE,      SELECT_TOKEN_STD},
        {CAP_SYS_ADMIN, CLASS_TOKEN_WRITE,      SELECT_TOKEN_AC},
        {CAP_SYS_ADMIN, CLASS_TOKEN_WRITE,      SELECT_TOKEN_BAT},
        /* used by userspace: fwupdate */
        {CAP_SYS_ADMIN, CLASS_ADMIN_PROP,       SELECT_ADMIN_PROP},
        /* used by userspace: fwupd */
        {CAP_SYS_ADMIN, CLASS_INFO,             SELECT_DOCK},
        {CAP_SYS_ADMIN, CLASS_FLASH_INTERFACE,  SELECT_FLASH_INTERFACE},
};

/* calls that are explicitly blacklisted */
static struct smbios_call call_blacklist[] = {
        {0x0000,  1,  7}, /* manufacturing use */
        {0x0000,  6,  5}, /* manufacturing use */
        {0x0000, 11,  3}, /* write once */
        {0x0000, 11,  7}, /* write once */
        {0x0000, 11, 11}, /* write once */
        {0x0000, 19, -1}, /* diagnostics */
        /* handled by kernel: dell-laptop */
        {0x0000, CLASS_INFO, SELECT_RFKILL},
        {0x0000, CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT},
};

struct token_range {
        u32 need_capability;
        u16 min;
        u16 max;
};

/* tokens that are whitelisted for given capabilities */
static struct token_range token_whitelist[] = {
        /* used by userspace: fwupdate */
        {CAP_SYS_ADMIN, CAPSULE_EN_TOKEN,       CAPSULE_DIS_TOKEN},
        /* can indicate to userspace that WMI is needed */
        {0x0000,        WSMT_EN_TOKEN,          WSMT_DIS_TOKEN}
};

/* tokens that are explicitly blacklisted */
static struct token_range token_blacklist[] = {
        {0x0000, 0x0058, 0x0059}, /* ME use */
        {0x0000, 0x00CD, 0x00D0}, /* raid shadow copy */
        {0x0000, 0x013A, 0x01FF}, /* sata shadow copy */
        {0x0000, 0x0175, 0x0176}, /* write once */
        {0x0000, 0x0195, 0x0197}, /* diagnostics */
        {0x0000, 0x01DC, 0x01DD}, /* manufacturing use */
        {0x0000, 0x027D, 0x0284}, /* diagnostics */
        {0x0000, 0x02E3, 0x02E3}, /* manufacturing use */
        {0x0000, 0x02FF, 0x02FF}, /* manufacturing use */
        {0x0000, 0x0300, 0x0302}, /* manufacturing use */
        {0x0000, 0x0325, 0x0326}, /* manufacturing use */
        {0x0000, 0x0332, 0x0335}, /* fan control */
        {0x0000, 0x0350, 0x0350}, /* manufacturing use */
        {0x0000, 0x0363, 0x0363}, /* manufacturing use */
        {0x0000, 0x0368, 0x0368}, /* manufacturing use */
        {0x0000, 0x03F6, 0x03F7}, /* manufacturing use */
        {0x0000, 0x049E, 0x049F}, /* manufacturing use */
        {0x0000, 0x04A0, 0x04A3}, /* disagnostics */
        {0x0000, 0x04E6, 0x04E7}, /* manufacturing use */
        {0x0000, 0x4000, 0x7FFF}, /* internal BIOS use */
        {0x0000, 0x9000, 0x9001}, /* internal BIOS use */
        {0x0000, 0xA000, 0xBFFF}, /* write only */
        {0x0000, 0xEFF0, 0xEFFF}, /* internal BIOS use */
        /* handled by kernel: dell-laptop */
        {0x0000, BRIGHTNESS_TOKEN,      BRIGHTNESS_TOKEN},
        {0x0000, KBD_LED_OFF_TOKEN,     KBD_LED_AUTO_TOKEN},
        {0x0000, KBD_LED_AC_TOKEN,      KBD_LED_AC_TOKEN},
        {0x0000, KBD_LED_AUTO_25_TOKEN, KBD_LED_AUTO_75_TOKEN},
        {0x0000, KBD_LED_AUTO_100_TOKEN,        KBD_LED_AUTO_100_TOKEN},
        {0x0000, GLOBAL_MIC_MUTE_ENABLE,        GLOBAL_MIC_MUTE_DISABLE},
};

static LIST_HEAD(smbios_device_list);

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);

int dell_smbios_register_device(struct device *d, void *call_fn)
{
        struct smbios_device *priv;

        priv = devm_kzalloc(d, sizeof(struct smbios_device), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;
        get_device(d);
        priv->device = d;
        priv->call_fn = call_fn;
        mutex_lock(&smbios_mutex);
        list_add_tail(&priv->list, &smbios_device_list);
        mutex_unlock(&smbios_mutex);
        dev_dbg(d, "Added device: %s\n", d->driver->name);
        return 0;
}
EXPORT_SYMBOL_GPL(dell_smbios_register_device);

void dell_smbios_unregister_device(struct device *d)
{
        struct smbios_device *priv;

        mutex_lock(&smbios_mutex);
        list_for_each_entry(priv, &smbios_device_list, list) {
                if (priv->device == d) {
                        list_del(&priv->list);
                        put_device(d);
                        break;
                }
        }
        mutex_unlock(&smbios_mutex);
        dev_dbg(d, "Remove device: %s\n", d->driver->name);
}
EXPORT_SYMBOL_GPL(dell_smbios_unregister_device);

int dell_smbios_call_filter(struct device *d,
                            struct calling_interface_buffer *buffer)
{
        u16 t = 0;
        int i;

        /* can't make calls over 30 */
        if (buffer->cmd_class > 30) {
                dev_dbg(d, "class too big: %u\n", buffer->cmd_class);
                return -EINVAL;
        }

        /* supported calls on the particular system */
        if (!(da_supported_commands & (1 << buffer->cmd_class))) {
                dev_dbg(d, "invalid command, supported commands: 0x%8x\n",
                        da_supported_commands);
                return -EINVAL;
        }

        /* match against call blacklist  */
        for (i = 0; i < ARRAY_SIZE(call_blacklist); i++) {
                if (buffer->cmd_class != call_blacklist[i].cmd_class)
                        continue;
                if (buffer->cmd_select != call_blacklist[i].cmd_select &&
                    call_blacklist[i].cmd_select != -1)
                        continue;
                dev_dbg(d, "blacklisted command: %u/%u\n",
                        buffer->cmd_class, buffer->cmd_select);
                return -EINVAL;
        }

        /* if a token call, find token ID */

        if ((buffer->cmd_class == CLASS_TOKEN_READ ||
             buffer->cmd_class == CLASS_TOKEN_WRITE) &&
             buffer->cmd_select < 3) {
                /* tokens enabled ? */
                if (!da_tokens) {
                        dev_dbg(d, "no token support on this system\n");
                        return -EINVAL;
                }

                /* find the matching token ID */
                for (i = 0; i < da_num_tokens; i++) {
                        if (da_tokens[i].location != buffer->input[0])
                                continue;
                        t = da_tokens[i].tokenID;
                        break;
                }

                /* token call; but token didn't exist */
                if (!t) {
                        dev_dbg(d, "token at location %04x doesn't exist\n",
                                buffer->input[0]);
                        return -EINVAL;
                }

                /* match against token blacklist */
                for (i = 0; i < ARRAY_SIZE(token_blacklist); i++) {
                        if (!token_blacklist[i].min || !token_blacklist[i].max)
                                continue;
                        if (t >= token_blacklist[i].min &&
                            t <= token_blacklist[i].max)
                                return -EINVAL;
                }

                /* match against token whitelist */
                for (i = 0; i < ARRAY_SIZE(token_whitelist); i++) {
                        if (!token_whitelist[i].min || !token_whitelist[i].max)
                                continue;
                        if (t < token_whitelist[i].min ||
                            t > token_whitelist[i].max)
                                continue;
                        if (!token_whitelist[i].need_capability ||
                            capable(token_whitelist[i].need_capability)) {
                                dev_dbg(d, "whitelisted token: %x\n", t);
                                return 0;
                        }

                }
        }
        /* match against call whitelist */
        for (i = 0; i < ARRAY_SIZE(call_whitelist); i++) {
                if (buffer->cmd_class != call_whitelist[i].cmd_class)
                        continue;
                if (buffer->cmd_select != call_whitelist[i].cmd_select)
                        continue;
                if (!call_whitelist[i].need_capability ||
                    capable(call_whitelist[i].need_capability)) {
                        dev_dbg(d, "whitelisted capable command: %u/%u\n",
                        buffer->cmd_class, buffer->cmd_select);
                        return 0;
                }
                dev_dbg(d, "missing capability %d for %u/%u\n",
                        call_whitelist[i].need_capability,
                        buffer->cmd_class, buffer->cmd_select);

        }

        /* not in a whitelist, only allow processes with capabilities */
        if (capable(CAP_SYS_RAWIO)) {
                dev_dbg(d, "Allowing %u/%u due to CAP_SYS_RAWIO\n",
                        buffer->cmd_class, buffer->cmd_select);
                return 0;
        }

        return -EACCES;
}
EXPORT_SYMBOL_GPL(dell_smbios_call_filter);

int dell_smbios_call(struct calling_interface_buffer *buffer)
{
        int (*call_fn)(struct calling_interface_buffer *) = NULL;
        struct device *selected_dev = NULL;
        struct smbios_device *priv;
        int ret;

        mutex_lock(&smbios_mutex);
        list_for_each_entry(priv, &smbios_device_list, list) {
                if (!selected_dev || priv->device->id >= selected_dev->id) {
                        dev_dbg(priv->device, "Trying device ID: %d\n",
                                priv->device->id);
                        call_fn = priv->call_fn;
                        selected_dev = priv->device;
                }
        }

        if (!selected_dev) {
                ret = -ENODEV;
                pr_err("No dell-smbios drivers are loaded\n");
                goto out_smbios_call;
        }

        ret = call_fn(buffer);

out_smbios_call:
        mutex_unlock(&smbios_mutex);
        return ret;
}
EXPORT_SYMBOL_GPL(dell_smbios_call);

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

        if (!da_tokens)
                return NULL;

        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_supported_commands = table->supportedCmds;

        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 zero_duplicates(struct device *dev)
{
        int i, j;

        for (i = 0; i < da_num_tokens; i++) {
                if (da_tokens[i].tokenID == 0)
                        continue;
                for (j = i+1; j < da_num_tokens; j++) {
                        if (da_tokens[j].tokenID == 0)
                                continue;
                        if (da_tokens[i].tokenID == da_tokens[j].tokenID) {
                                dev_dbg(dev, "Zeroing dup token ID %x(%x/%x)\n",
                                        da_tokens[j].tokenID,
                                        da_tokens[j].location,
                                        da_tokens[j].value);
                                da_tokens[j].tokenID = 0;
                        }
                }
        }
}

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 match_attribute(struct device *dev,
                           struct device_attribute *attr)
{
        int i;

        for (i = 0; i < da_num_tokens * 2; i++) {
                if (!token_attrs[i])
                        continue;
                if (strcmp(token_attrs[i]->name, attr->attr.name) == 0)
                        return i/2;
        }
        dev_dbg(dev, "couldn't match: %s\n", attr->attr.name);
        return -EINVAL;
}

static ssize_t location_show(struct device *dev,
                             struct device_attribute *attr, char *buf)
{
        int i;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        i = match_attribute(dev, attr);
        if (i > 0)
                return scnprintf(buf, PAGE_SIZE, "%08x", da_tokens[i].location);
        return 0;
}

static ssize_t value_show(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        int i;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        i = match_attribute(dev, attr);
        if (i > 0)
                return scnprintf(buf, PAGE_SIZE, "%08x", da_tokens[i].value);
        return 0;
}

static struct attribute_group smbios_attribute_group = {
        .name = "tokens"
};

static struct platform_driver platform_driver = {
        .driver = {
                .name = "dell-smbios",
        },
};

static int build_tokens_sysfs(struct platform_device *dev)
{
        char *location_name;
        char *value_name;
        size_t size;
        int ret;
        int i, j;

        /* (number of tokens  + 1 for null terminated */
        size = sizeof(struct device_attribute) * (da_num_tokens + 1);
        token_location_attrs = kzalloc(size, GFP_KERNEL);
        if (!token_location_attrs)
                return -ENOMEM;
        token_value_attrs = kzalloc(size, GFP_KERNEL);
        if (!token_value_attrs)
                goto out_allocate_value;

        /* need to store both location and value + terminator*/
        size = sizeof(struct attribute *) * ((2 * da_num_tokens) + 1);
        token_attrs = kzalloc(size, GFP_KERNEL);
        if (!token_attrs)
                goto out_allocate_attrs;

        for (i = 0, j = 0; i < da_num_tokens; i++) {
                /* skip empty */
                if (da_tokens[i].tokenID == 0)
                        continue;
                /* add location */
                location_name = kasprintf(GFP_KERNEL, "%04x_location",
                                          da_tokens[i].tokenID);
                if (location_name == NULL)
                        goto out_unwind_strings;
                sysfs_attr_init(&token_location_attrs[i].attr);
                token_location_attrs[i].attr.name = location_name;
                token_location_attrs[i].attr.mode = 0444;
                token_location_attrs[i].show = location_show;
                token_attrs[j++] = &token_location_attrs[i].attr;

                /* add value */
                value_name = kasprintf(GFP_KERNEL, "%04x_value",
                                       da_tokens[i].tokenID);
                if (value_name == NULL)
                        goto loop_fail_create_value;
                sysfs_attr_init(&token_value_attrs[i].attr);
                token_value_attrs[i].attr.name = value_name;
                token_value_attrs[i].attr.mode = 0444;
                token_value_attrs[i].show = value_show;
                token_attrs[j++] = &token_value_attrs[i].attr;
                continue;

loop_fail_create_value:
                kfree(location_name);
                goto out_unwind_strings;
        }
        smbios_attribute_group.attrs = token_attrs;

        ret = sysfs_create_group(&dev->dev.kobj, &smbios_attribute_group);
        if (ret)
                goto out_unwind_strings;
        return 0;

out_unwind_strings:
        while (i--) {
                kfree(token_location_attrs[i].attr.name);
                kfree(token_value_attrs[i].attr.name);
        }
        kfree(token_attrs);
out_allocate_attrs:
        kfree(token_value_attrs);
out_allocate_value:
        kfree(token_location_attrs);

        return -ENOMEM;
}

static void free_group(struct platform_device *pdev)
{
        int i;

        sysfs_remove_group(&pdev->dev.kobj,
                                &smbios_attribute_group);
        for (i = 0; i < da_num_tokens; i++) {
                kfree(token_location_attrs[i].attr.name);
                kfree(token_value_attrs[i].attr.name);
        }
        kfree(token_attrs);
        kfree(token_value_attrs);
        kfree(token_location_attrs);
}

static int __init dell_smbios_init(void)
{
        int ret, wmi, smm;

        if (!dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "Dell System", NULL) &&
            !dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "www.dell.com", NULL)) {
                pr_err("Unable to run on non-Dell system\n");
                return -ENODEV;
        }

        dmi_walk(find_tokens, NULL);

        ret = platform_driver_register(&platform_driver);
        if (ret)
                goto fail_platform_driver;

        platform_device = platform_device_alloc("dell-smbios", 0);
        if (!platform_device) {
                ret = -ENOMEM;
                goto fail_platform_device_alloc;
        }
        ret = platform_device_add(platform_device);
        if (ret)
                goto fail_platform_device_add;

        /* register backends */
        wmi = init_dell_smbios_wmi();
        if (wmi)
                pr_debug("Failed to initialize WMI backend: %d\n", wmi);
        smm = init_dell_smbios_smm();
        if (smm)
                pr_debug("Failed to initialize SMM backend: %d\n", smm);
        if (wmi && smm) {
                pr_err("No SMBIOS backends available (wmi: %d, smm: %d)\n",
                        wmi, smm);
                ret = -ENODEV;
                goto fail_create_group;
        }

        if (da_tokens)  {
                /* duplicate tokens will cause problems building sysfs files */
                zero_duplicates(&platform_device->dev);

                ret = build_tokens_sysfs(platform_device);
                if (ret)
                        goto fail_sysfs;
        }

        return 0;

fail_sysfs:
        free_group(platform_device);

fail_create_group:
        platform_device_del(platform_device);

fail_platform_device_add:
        platform_device_put(platform_device);

fail_platform_device_alloc:
        platform_driver_unregister(&platform_driver);

fail_platform_driver:
        kfree(da_tokens);
        return ret;
}

static void __exit dell_smbios_exit(void)
{
        exit_dell_smbios_wmi();
        exit_dell_smbios_smm();
        mutex_lock(&smbios_mutex);
        if (platform_device) {
                if (da_tokens)
                        free_group(platform_device);
                platform_device_unregister(platform_device);
                platform_driver_unregister(&platform_driver);
        }
        kfree(da_tokens);
        mutex_unlock(&smbios_mutex);
}

module_init(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@kernel.org>");
MODULE_AUTHOR("Mario Limonciello <mario.limonciello@outlook.com>");
MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
MODULE_LICENSE("GPL");