// SPDX-License-Identifier: GPL-2.0-only
/*
 * ACPI configfs support
 *
 * Copyright (c) 2016 Intel Corporation
 */

#define pr_fmt(fmt) "ACPI configfs: " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/configfs.h>
#include <linux/acpi.h>
#include <linux/security.h>

static struct config_group *acpi_table_group;

struct acpi_table {
        struct config_item cfg;
        struct acpi_table_header *header;
        u32 index;
};

static ssize_t acpi_table_aml_write(struct config_item *cfg,
                                    const void *data, size_t size)
{
        const struct acpi_table_header *header = data;
        struct acpi_table *table;
        int ret = security_locked_down(LOCKDOWN_ACPI_TABLES);

        if (ret)
                return ret;

        table = container_of(cfg, struct acpi_table, cfg);

        if (table->header) {
                pr_err("table already loaded\n");
                return -EBUSY;
        }

        if (header->length != size) {
                pr_err("invalid table length\n");
                return -EINVAL;
        }

        if (memcmp(header->signature, ACPI_SIG_SSDT, 4)) {
                pr_err("invalid table signature\n");
                return -EINVAL;
        }

        table = container_of(cfg, struct acpi_table, cfg);

        table->header = kmemdup(header, header->length, GFP_KERNEL);
        if (!table->header)
                return -ENOMEM;

        ret = acpi_load_table(table->header, &table->index);
        if (ret) {
                kfree(table->header);
                table->header = NULL;
        }

        return ret;
}

static inline struct acpi_table_header *get_header(struct config_item *cfg)
{
        struct acpi_table *table = container_of(cfg, struct acpi_table, cfg);

        if (!table->header)
                pr_err("table not loaded\n");

        return table->header ?: ERR_PTR(-EINVAL);
}

static ssize_t acpi_table_aml_read(struct config_item *cfg,
                                   void *data, size_t size)
{
        struct acpi_table_header *h = get_header(cfg);

        if (IS_ERR(h))
                return PTR_ERR(h);

        if (data)
                memcpy(data, h, h->length);

        return h->length;
}

#define MAX_ACPI_TABLE_SIZE (128 * 1024)

CONFIGFS_BIN_ATTR(acpi_table_, aml, NULL, MAX_ACPI_TABLE_SIZE);

static struct configfs_bin_attribute *acpi_table_bin_attrs[] = {
        &acpi_table_attr_aml,
        NULL,
};

static ssize_t acpi_table_signature_show(struct config_item *cfg, char *str)
{
        struct acpi_table_header *h = get_header(cfg);

        if (IS_ERR(h))
                return PTR_ERR(h);

        return sysfs_emit(str, "%.*s\n", ACPI_NAMESEG_SIZE, h->signature);
}

static ssize_t acpi_table_length_show(struct config_item *cfg, char *str)
{
        struct acpi_table_header *h = get_header(cfg);

        if (IS_ERR(h))
                return PTR_ERR(h);

        return sysfs_emit(str, "%d\n", h->length);
}

static ssize_t acpi_table_revision_show(struct config_item *cfg, char *str)
{
        struct acpi_table_header *h = get_header(cfg);

        if (IS_ERR(h))
                return PTR_ERR(h);

        return sysfs_emit(str, "%d\n", h->revision);
}

static ssize_t acpi_table_oem_id_show(struct config_item *cfg, char *str)
{
        struct acpi_table_header *h = get_header(cfg);

        if (IS_ERR(h))
                return PTR_ERR(h);

        return sysfs_emit(str, "%.*s\n", ACPI_OEM_ID_SIZE, h->oem_id);
}

static ssize_t acpi_table_oem_table_id_show(struct config_item *cfg, char *str)
{
        struct acpi_table_header *h = get_header(cfg);

        if (IS_ERR(h))
                return PTR_ERR(h);

        return sysfs_emit(str, "%.*s\n", ACPI_OEM_TABLE_ID_SIZE, h->oem_table_id);
}

static ssize_t acpi_table_oem_revision_show(struct config_item *cfg, char *str)
{
        struct acpi_table_header *h = get_header(cfg);

        if (IS_ERR(h))
                return PTR_ERR(h);

        return sysfs_emit(str, "%d\n", h->oem_revision);
}

static ssize_t acpi_table_asl_compiler_id_show(struct config_item *cfg,
                                               char *str)
{
        struct acpi_table_header *h = get_header(cfg);

        if (IS_ERR(h))
                return PTR_ERR(h);

        return sysfs_emit(str, "%.*s\n", ACPI_NAMESEG_SIZE, h->asl_compiler_id);
}

static ssize_t acpi_table_asl_compiler_revision_show(struct config_item *cfg,
                                                     char *str)
{
        struct acpi_table_header *h = get_header(cfg);

        if (IS_ERR(h))
                return PTR_ERR(h);

        return sysfs_emit(str, "%d\n", h->asl_compiler_revision);
}

CONFIGFS_ATTR_RO(acpi_table_, signature);
CONFIGFS_ATTR_RO(acpi_table_, length);
CONFIGFS_ATTR_RO(acpi_table_, revision);
CONFIGFS_ATTR_RO(acpi_table_, oem_id);
CONFIGFS_ATTR_RO(acpi_table_, oem_table_id);
CONFIGFS_ATTR_RO(acpi_table_, oem_revision);
CONFIGFS_ATTR_RO(acpi_table_, asl_compiler_id);
CONFIGFS_ATTR_RO(acpi_table_, asl_compiler_revision);

static struct configfs_attribute *acpi_table_attrs[] = {
        &acpi_table_attr_signature,
        &acpi_table_attr_length,
        &acpi_table_attr_revision,
        &acpi_table_attr_oem_id,
        &acpi_table_attr_oem_table_id,
        &acpi_table_attr_oem_revision,
        &acpi_table_attr_asl_compiler_id,
        &acpi_table_attr_asl_compiler_revision,
        NULL,
};

static const struct config_item_type acpi_table_type = {
        .ct_owner = THIS_MODULE,
        .ct_bin_attrs = acpi_table_bin_attrs,
        .ct_attrs = acpi_table_attrs,
};

static struct config_item *acpi_table_make_item(struct config_group *group,
                                                const char *name)
{
        struct acpi_table *table;

        table = kzalloc_obj(*table);
        if (!table)
                return ERR_PTR(-ENOMEM);

        config_item_init_type_name(&table->cfg, name, &acpi_table_type);
        return &table->cfg;
}

static void acpi_table_drop_item(struct config_group *group,
                                 struct config_item *cfg)
{
        struct acpi_table *table = container_of(cfg, struct acpi_table, cfg);

        pr_debug("Host-directed Dynamic ACPI Table Unload\n");
        acpi_unload_table(table->index);
        config_item_put(cfg);
}

static struct configfs_group_operations acpi_table_group_ops = {
        .make_item = acpi_table_make_item,
        .drop_item = acpi_table_drop_item,
};

static const struct config_item_type acpi_tables_type = {
        .ct_owner = THIS_MODULE,
        .ct_group_ops = &acpi_table_group_ops,
};

static const struct config_item_type acpi_root_group_type = {
        .ct_owner = THIS_MODULE,
};

static struct configfs_subsystem acpi_configfs = {
        .su_group = {
                .cg_item = {
                        .ci_namebuf = "acpi",
                        .ci_type = &acpi_root_group_type,
                },
        },
        .su_mutex = __MUTEX_INITIALIZER(acpi_configfs.su_mutex),
};

static int __init acpi_configfs_init(void)
{
        int ret;
        struct config_group *root = &acpi_configfs.su_group;

        config_group_init(root);

        ret = configfs_register_subsystem(&acpi_configfs);
        if (ret)
                return ret;

        acpi_table_group = configfs_register_default_group(root, "table",
                                                           &acpi_tables_type);
        if (IS_ERR(acpi_table_group)) {
                configfs_unregister_subsystem(&acpi_configfs);
                return PTR_ERR(acpi_table_group);
        }

        return 0;
}
module_init(acpi_configfs_init);

static void __exit acpi_configfs_exit(void)
{
        configfs_unregister_default_group(acpi_table_group);
        configfs_unregister_subsystem(&acpi_configfs);
}
module_exit(acpi_configfs_exit);

MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
MODULE_DESCRIPTION("ACPI configfs support");
MODULE_LICENSE("GPL v2");