drivers/acpi/ec_sys.c

// 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(write_support, bool, 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);