// SPDX-License-Identifier: GPL-2.0-only
/*
 * vpd.c
 *
 * Driver for exporting VPD content to sysfs.
 *
 * Copyright 2017 Google Inc.
 */

#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/sysfs.h>

#include "coreboot_table.h"
#include "vpd_decode.h"

#define CB_TAG_VPD      0x2c
#define VPD_CBMEM_MAGIC 0x43524f53

static struct kobject *vpd_kobj;

struct vpd_cbmem {
        u32 magic;
        u32 version;
        u32 ro_size;
        u32 rw_size;
        u8  blob[];
};

struct vpd_section {
        bool enabled;
        const char *name;
        char *raw_name;                /* the string name_raw */
        struct kobject *kobj;          /* vpd/name directory */
        char *baseaddr;
        struct bin_attribute bin_attr; /* vpd/name_raw bin_attribute */
        struct list_head attribs;      /* key/value in vpd_attrib_info list */
};

struct vpd_attrib_info {
        char *key;
        const char *value;
        struct bin_attribute bin_attr;
        struct list_head list;
};

static struct vpd_section ro_vpd;
static struct vpd_section rw_vpd;

static ssize_t vpd_attrib_read(struct file *filp, struct kobject *kobp,
                               const struct bin_attribute *bin_attr, char *buf,
                               loff_t pos, size_t count)
{
        struct vpd_attrib_info *info = bin_attr->private;

        return memory_read_from_buffer(buf, count, &pos, info->value,
                                       info->bin_attr.size);
}

/*
 * vpd_section_check_key_name()
 *
 * The VPD specification supports only [a-zA-Z0-9_]+ characters in key names but
 * old firmware versions may have entries like "S/N" which are problematic when
 * exporting them as sysfs attributes. These keys present in old firmwares are
 * ignored.
 *
 * Returns VPD_OK for a valid key name, VPD_FAIL otherwise.
 *
 * @key: The key name to check
 * @key_len: key name length
 */
static int vpd_section_check_key_name(const u8 *key, s32 key_len)
{
        int c;

        while (key_len-- > 0) {
                c = *key++;

                if (!isalnum(c) && c != '_')
                        return VPD_FAIL;
        }

        return VPD_OK;
}

static int vpd_section_attrib_add(const u8 *key, u32 key_len,
                                  const u8 *value, u32 value_len,
                                  void *arg)
{
        int ret;
        struct vpd_section *sec = arg;
        struct vpd_attrib_info *info;

        /*
         * Return VPD_OK immediately to decode next entry if the current key
         * name contains invalid characters.
         */
        if (vpd_section_check_key_name(key, key_len) != VPD_OK)
                return VPD_OK;

        info = kzalloc_obj(*info);
        if (!info)
                return -ENOMEM;

        info->key = kstrndup(key, key_len, GFP_KERNEL);
        if (!info->key) {
                ret = -ENOMEM;
                goto free_info;
        }

        sysfs_bin_attr_init(&info->bin_attr);
        info->bin_attr.attr.name = info->key;
        info->bin_attr.attr.mode = 0444;
        info->bin_attr.size = value_len;
        info->bin_attr.read = vpd_attrib_read;
        info->bin_attr.private = info;

        info->value = value;

        INIT_LIST_HEAD(&info->list);

        ret = sysfs_create_bin_file(sec->kobj, &info->bin_attr);
        if (ret)
                goto free_info_key;

        list_add_tail(&info->list, &sec->attribs);
        return 0;

free_info_key:
        kfree(info->key);
free_info:
        kfree(info);

        return ret;
}

static void vpd_section_attrib_destroy(struct vpd_section *sec)
{
        struct vpd_attrib_info *info;
        struct vpd_attrib_info *temp;

        list_for_each_entry_safe(info, temp, &sec->attribs, list) {
                sysfs_remove_bin_file(sec->kobj, &info->bin_attr);
                kfree(info->key);
                kfree(info);
        }
}

static ssize_t vpd_section_read(struct file *filp, struct kobject *kobp,
                                const struct bin_attribute *bin_attr, char *buf,
                                loff_t pos, size_t count)
{
        struct vpd_section *sec = bin_attr->private;

        return memory_read_from_buffer(buf, count, &pos, sec->baseaddr,
                                       sec->bin_attr.size);
}

static int vpd_section_create_attribs(struct vpd_section *sec)
{
        s32 consumed;
        int ret;

        consumed = 0;
        do {
                ret = vpd_decode_string(sec->bin_attr.size, sec->baseaddr,
                                        &consumed, vpd_section_attrib_add, sec);
        } while (ret == VPD_OK);

        return 0;
}

static int vpd_section_init(const char *name, struct vpd_section *sec,
                            phys_addr_t physaddr, size_t size)
{
        int err;

        sec->baseaddr = memremap(physaddr, size, MEMREMAP_WB);
        if (!sec->baseaddr)
                return -ENOMEM;

        sec->name = name;

        /* We want to export the raw partition with name ${name}_raw */
        sec->raw_name = kasprintf(GFP_KERNEL, "%s_raw", name);
        if (!sec->raw_name) {
                err = -ENOMEM;
                goto err_memunmap;
        }

        sysfs_bin_attr_init(&sec->bin_attr);
        sec->bin_attr.attr.name = sec->raw_name;
        sec->bin_attr.attr.mode = 0444;
        sec->bin_attr.size = size;
        sec->bin_attr.read = vpd_section_read;
        sec->bin_attr.private = sec;

        err = sysfs_create_bin_file(vpd_kobj, &sec->bin_attr);
        if (err)
                goto err_free_raw_name;

        sec->kobj = kobject_create_and_add(name, vpd_kobj);
        if (!sec->kobj) {
                err = -EINVAL;
                goto err_sysfs_remove;
        }

        INIT_LIST_HEAD(&sec->attribs);
        vpd_section_create_attribs(sec);

        sec->enabled = true;

        return 0;

err_sysfs_remove:
        sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
err_free_raw_name:
        kfree(sec->raw_name);
err_memunmap:
        memunmap(sec->baseaddr);
        return err;
}

static int vpd_section_destroy(struct vpd_section *sec)
{
        if (sec->enabled) {
                vpd_section_attrib_destroy(sec);
                kobject_put(sec->kobj);
                sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
                kfree(sec->raw_name);
                memunmap(sec->baseaddr);
                sec->enabled = false;
        }

        return 0;
}

static int vpd_sections_init(phys_addr_t physaddr)
{
        struct vpd_cbmem *temp;
        struct vpd_cbmem header;
        int ret = 0;

        temp = memremap(physaddr, sizeof(struct vpd_cbmem), MEMREMAP_WB);
        if (!temp)
                return -ENOMEM;

        memcpy(&header, temp, sizeof(struct vpd_cbmem));
        memunmap(temp);

        if (header.magic != VPD_CBMEM_MAGIC)
                return -ENODEV;

        if (header.ro_size) {
                ret = vpd_section_init("ro", &ro_vpd,
                                       physaddr + sizeof(struct vpd_cbmem),
                                       header.ro_size);
                if (ret)
                        return ret;
        }

        if (header.rw_size) {
                ret = vpd_section_init("rw", &rw_vpd,
                                       physaddr + sizeof(struct vpd_cbmem) +
                                       header.ro_size, header.rw_size);
                if (ret) {
                        vpd_section_destroy(&ro_vpd);
                        return ret;
                }
        }

        return 0;
}

static int vpd_probe(struct coreboot_device *dev)
{
        int ret;

        vpd_kobj = kobject_create_and_add("vpd", firmware_kobj);
        if (!vpd_kobj)
                return -ENOMEM;

        ret = vpd_sections_init(dev->cbmem_ref.cbmem_addr);
        if (ret) {
                kobject_put(vpd_kobj);
                return ret;
        }

        return 0;
}

static void vpd_remove(struct coreboot_device *dev)
{
        vpd_section_destroy(&ro_vpd);
        vpd_section_destroy(&rw_vpd);

        kobject_put(vpd_kobj);
}

static const struct coreboot_device_id vpd_ids[] = {
        { .tag = CB_TAG_VPD },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(coreboot, vpd_ids);

static struct coreboot_driver vpd_driver = {
        .probe = vpd_probe,
        .remove = vpd_remove,
        .drv = {
                .name = "vpd",
        },
        .id_table = vpd_ids,
};
module_coreboot_driver(vpd_driver);

MODULE_AUTHOR("Google, Inc.");
MODULE_DESCRIPTION("Driver for exporting Vital Product Data content to sysfs");
MODULE_LICENSE("GPL");