// SPDX-License-Identifier: GPL-2.0-only
/*
 * ec_sys.c
 *
 * Copyright (C) 2010 SUSE Products GmbH/Novell
 * Author:
 *      Thomas Renninger <trenn@suse.de>
 */

#include <linux/kernel.h>
#include <linux/acpi.h>
#include <linux/debugfs.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include "internal.h"

MODULE_AUTHOR("Thomas Renninger <trenn@suse.de>");
MODULE_DESCRIPTION("ACPI EC sysfs access driver");
MODULE_LICENSE("GPL");

static bool write_support;
module_param_hw(write_support, bool, other, 0644);
MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may "
                 "be needed.");

#define EC_SPACE_SIZE 256

static struct dentry *acpi_ec_debugfs_dir;

static ssize_t acpi_ec_read_io(struct file *f, char __user *buf,
                               size_t count, loff_t *off)
{
        /* Use this if support reading/writing multiple ECs exists in ec.c:
         * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
         */
        unsigned int size = EC_SPACE_SIZE;
        loff_t init_off = *off;
        int err = 0;

        if (*off >= size)
                return 0;
        if (*off + count >= size) {
                size -= *off;
                count = size;
        } else
                size = count;

        while (size) {
                u8 byte_read;
                err = ec_read(*off, &byte_read);
                if (err)
                        return err;
                if (put_user(byte_read, buf + *off - init_off)) {
                        if (*off - init_off)
                                return *off - init_off; /* partial read */
                        return -EFAULT;
                }
                *off += 1;
                size--;
        }
        return count;
}

static ssize_t acpi_ec_write_io(struct file *f, const char __user *buf,
                                size_t count, loff_t *off)
{
        /* Use this if support reading/writing multiple ECs exists in ec.c:
         * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
         */

        unsigned int size = count;
        loff_t init_off = *off;
        int err = 0;

        if (!write_support)
                return -EINVAL;

        if (*off >= EC_SPACE_SIZE)
                return 0;
        if (*off + count >= EC_SPACE_SIZE) {
                size = EC_SPACE_SIZE - *off;
                count = size;
        }

        while (size) {
                u8 byte_write;
                if (get_user(byte_write, buf + *off - init_off)) {
                        if (*off - init_off)
                                return *off - init_off; /* partial write */
                        return -EFAULT;
                }
                err = ec_write(*off, byte_write);
                if (err)
                        return err;

                *off += 1;
                size--;
        }
        return count;
}

static const struct file_operations acpi_ec_io_ops = {
        .owner = THIS_MODULE,
        .open  = simple_open,
        .read  = acpi_ec_read_io,
        .write = acpi_ec_write_io,
        .llseek = default_llseek,
};

static void acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count)
{
        struct dentry *dev_dir;
        char name[64];
        umode_t mode = 0400;

        if (ec_device_count == 0)
                acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL);

        sprintf(name, "ec%u", ec_device_count);
        dev_dir = debugfs_create_dir(name, acpi_ec_debugfs_dir);

        debugfs_create_x32("gpe", 0444, dev_dir, &first_ec->gpe);
        debugfs_create_bool("use_global_lock", 0444, dev_dir,
                            &first_ec->global_lock);

        if (write_support)
                mode = 0600;
        debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops);
}

static int __init acpi_ec_sys_init(void)
{
        if (first_ec)
                acpi_ec_add_debugfs(first_ec, 0);
        return 0;
}

static void __exit acpi_ec_sys_exit(void)
{
        debugfs_remove_recursive(acpi_ec_debugfs_dir);
}

module_init(acpi_ec_sys_init);
module_exit(acpi_ec_sys_exit);