path: root/drivers/acpi/ec.c

/*
 *  ec.c - ACPI Embedded Controller Driver (v2.0)
 *
 *  Copyright (C) 2006, 2007 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
 *  Copyright (C) 2006 Denis Sadykov <denis.m.sadykov@intel.com>
 *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <asm/io.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include <acpi/actypes.h>

#define ACPI_EC_CLASS			"embedded_controller"
#define ACPI_EC_HID			"PNP0C09"
#define ACPI_EC_DEVICE_NAME		"Embedded Controller"
#define ACPI_EC_FILE_INFO		"info"
#undef PREFIX
#define PREFIX				"ACPI: EC: "

/* EC status register */
#define ACPI_EC_FLAG_OBF	0x01	/* Output buffer full */
#define ACPI_EC_FLAG_IBF	0x02	/* Input buffer full */
#define ACPI_EC_FLAG_BURST	0x10	/* burst mode */
#define ACPI_EC_FLAG_SCI	0x20	/* EC-SCI occurred */

/* EC commands */
enum ec_command {
	ACPI_EC_COMMAND_READ = 0x80,
	ACPI_EC_COMMAND_WRITE = 0x81,
	ACPI_EC_BURST_ENABLE = 0x82,
	ACPI_EC_BURST_DISABLE = 0x83,
	ACPI_EC_COMMAND_QUERY = 0x84,
};
/* EC events */
enum ec_event {
	ACPI_EC_EVENT_OBF_1 = 1,	/* Output buffer full */
	ACPI_EC_EVENT_IBF_0,	/* Input buffer empty */
};

#define ACPI_EC_DELAY		500	/* Wait 500ms max. during EC ops */
#define ACPI_EC_UDELAY_GLK	1000	/* Wait 1ms max. to get global lock */

static enum ec_mode {
	EC_INTR = 1,		/* Output buffer full */
	EC_POLL,		/* Input buffer empty */
} acpi_ec_mode = EC_INTR;

static int acpi_ec_remove(struct acpi_device *device, int type);
static int acpi_ec_start(struct acpi_device *device);
static int acpi_ec_stop(struct acpi_device *device, int type);
static int acpi_ec_add(struct acpi_device *device);

static struct acpi_driver acpi_ec_driver = {
	.name = "ec",
	.class = ACPI_EC_CLASS,
	.ids = ACPI_EC_HID,
	.ops = {
		.add = acpi_ec_add,
		.remove = acpi_ec_remove,
		.start = acpi_ec_start,
		.stop = acpi_ec_stop,
		},
};

/* If we find an EC via the ECDT, we need to keep a ptr to its context */
/* External interfaces use first EC only, so remember */
static struct acpi_ec {
	acpi_handle handle;
	unsigned long gpe;
	unsigned long command_addr;
	unsigned long data_addr;
	unsigned long global_lock;
	struct mutex lock;
	atomic_t query_pending;
	atomic_t event_count;
	wait_queue_head_t wait;
} *boot_ec, *first_ec;

/* --------------------------------------------------------------------------
                             Transaction Management
   -------------------------------------------------------------------------- */

static inline u8 acpi_ec_read_status(struct acpi_ec *ec)
{
	return inb(ec->command_addr);
}

static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
{
	return inb(ec->data_addr);
}

static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
{
	outb(command, ec->command_addr);
}

static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
{
	outb(data, ec->data_addr);
}

static inline int acpi_ec_check_status(struct acpi_ec *ec, enum ec_event event,
				       unsigned old_count)
{
	u8 status = acpi_ec_read_status(ec);
	if (old_count == atomic_read(&ec->event_count))
		return 0;
	if (event == ACPI_EC_EVENT_OBF_1) {
		if (status & ACPI_EC_FLAG_OBF)
			return 1;
	} else if (event == ACPI_EC_EVENT_IBF_0) {
		if (!(status & ACPI_EC_FLAG_IBF))
			return 1;
	}

	return 0;
}

static int acpi_ec_wait(struct acpi_ec *ec, enum ec_event event,
                        unsigned count, int force_poll)
{
	if (unlikely(force_poll) || acpi_ec_mode == EC_POLL) {
		unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
		while (time_before(jiffies, delay)) {
			if (acpi_ec_check_status(ec, event, 0))
				return 0;
		}
	} else {
		if (wait_event_timeout(ec->wait,
				       acpi_ec_check_status(ec, event, count),
				       msecs_to_jiffies(ACPI_EC_DELAY)) ||
		    acpi_ec_check_status(ec, event, 0)) {
			return 0;
		} else {
			printk(KERN_ERR PREFIX "acpi_ec_wait timeout,"
			       " status = %d, expect_event = %d\n",
			       acpi_ec_read_status(ec), event);
		}
	}

	return -ETIME;
}

static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, u8 command,
					const u8 * wdata, unsigned wdata_len,
					u8 * rdata, unsigned rdata_len,
					int force_poll)
{
	int result = 0;
	unsigned count = atomic_read(&ec->event_count);
	acpi_ec_write_cmd(ec, command);

	for (; wdata_len > 0; --wdata_len) {
		result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, count, force_poll);
		if (result) {
			printk(KERN_ERR PREFIX
			       "write_cmd timeout, command = %d\n", command);
			goto end;
		}
		count = atomic_read(&ec->event_count);
		acpi_ec_write_data(ec, *(wdata++));
	}

	if (!rdata_len) {
		result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, count, force_poll);
		if (result) {
			printk(KERN_ERR PREFIX
			       "finish-write timeout, command = %d\n", command);
			goto end;
		}
	} else if (command == ACPI_EC_COMMAND_QUERY) {
		atomic_set(&ec->query_pending, 0);
	}

	for (; rdata_len > 0; --rdata_len) {
		result = acpi_ec_wait(ec, ACPI_EC_EVENT_OBF_1, count, force_poll);
		if (result) {
			printk(KERN_ERR PREFIX "read timeout, command = %d\n",
			       command);
			goto end;
		}
		count = atomic_read(&ec->event_count);
		*(rdata++) = acpi_ec_read_data(ec);
	}
      end:
	return result;
}

static int acpi_ec_transaction(struct acpi_ec *ec, u8 command,
			       const u8 * wdata, unsigned wdata_len,
			       u8 * rdata, unsigned rdata_len,
			       int force_poll)
{
	int status;
	u32 glk;

	if (!ec || (wdata_len && !wdata) || (rdata_len && !rdata))
		return -EINVAL;

	if (rdata)
		memset(rdata, 0, rdata_len);

	mutex_lock(&ec->lock);
	if (ec->global_lock) {
		status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
		if (ACPI_FAILURE(status)) {
			mutex_unlock(&ec->lock);
			return -ENODEV;
		}
	}

	/* Make sure GPE is enabled before doing transaction */
	acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);

	status = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, 0, 0);
	if (status) {
		printk(KERN_ERR PREFIX
		       "input buffer is not empty, aborting transaction\n");
		goto end;
	}

	status = acpi_ec_transaction_unlocked(ec, command,
					      wdata, wdata_len,
					      rdata, rdata_len,
					      force_poll);

      end:

	if (ec->global_lock)
		acpi_release_global_lock(glk);
	mutex_unlock(&ec->lock);

	return status;
}

/*
 * Note: samsung nv5000 doesn't work with ec burst mode.
 * http://bugzilla.kernel.org/show_bug.cgi?id=4980
 */
int acpi_ec_burst_enable(struct acpi_ec *ec)
{
	u8 d;
	return acpi_ec_transaction(ec, ACPI_EC_BURST_ENABLE, NULL, 0, &d, 1, 0);
}

int acpi_ec_burst_disable(struct acpi_ec *ec)
{
	return acpi_ec_transaction(ec, ACPI_EC_BURST_DISABLE, NULL, 0, NULL, 0, 0);
}

static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 * data)
{
	int result;
	u8 d;

	result = acpi_ec_transaction(ec, ACPI_EC_COMMAND_READ,
				     &address, 1, &d, 1, 0);
	*data = d;
	return result;
}

static int acpi_ec_write(struct acpi_ec *ec, u8 address, u8 data)
{
	u8 wdata[2] = { address, data };
	return acpi_ec_transaction(ec, ACPI_EC_COMMAND_WRITE,
				   wdata, 2, NULL, 0, 0);
}

/*
 * Externally callable EC access functions. For now, assume 1 EC only
 */
int ec_burst_enable(void)
{
	if (!first_ec)
		return -ENODEV;
	return acpi_ec_burst_enable(first_ec);
}

EXPORT_SYMBOL(ec_burst_enable);

int ec_burst_disable(void)
{
	if (!first_ec)
		return -ENODEV;
	return acpi_ec_burst_disable(first_ec);
}

EXPORT_SYMBOL(ec_burst_disable);

int ec_read(u8 addr, u8 * val)
{
	int err;
	u8 temp_data;

	if (!first_ec)
		return -ENODEV;

	err = acpi_ec_read(first_ec, addr, &temp_data);

	if (!err) {
		*val = temp_data;
		return 0;
	} else
		return err;
}

EXPORT_SYMBOL(ec_read);

int ec_write(u8 addr, u8 val)
{
	int err;

	if (!first_ec)
		return -ENODEV;

	err = acpi_ec_write(first_ec, addr, val);

	return err;
}

EXPORT_SYMBOL(ec_write);

int ec_transaction(u8 command,
		   const u8 * wdata, unsigned wdata_len,
		   u8 * rdata, unsigned rdata_len,
		   int force_poll)
{
	if (!first_ec)
		return -ENODEV;

	return acpi_ec_transaction(first_ec, command, wdata,
				   wdata_len, rdata, rdata_len,
				   force_poll);
}

EXPORT_SYMBOL(ec_transaction);

static int acpi_ec_query(struct acpi_ec *ec, u8 * data)
{
	int result;
	u8 d;

	if (!ec || !data)
		return -EINVAL;

	/*
	 * Query the EC to find out which _Qxx method we need to evaluate.
	 * Note that successful completion of the query causes the ACPI_EC_SCI
	 * bit to be cleared (and thus clearing the interrupt source).
	 */

	result = acpi_ec_transaction(ec, ACPI_EC_COMMAND_QUERY, NULL, 0, &d, 1, 0);
	if (result)
		return result;

	if (!d)
		return -ENODATA;

	*data = d;
	return 0;
}

/* --------------------------------------------------------------------------
                                Event Management
   -------------------------------------------------------------------------- */

static void acpi_ec_gpe_query(void *ec_cxt)
{
	struct acpi_ec *ec = ec_cxt;
	u8 value = 0;
	char object_name[8];

	if (!ec || acpi_ec_query(ec, &value))
		return;

	snprintf(object_name, 8, "_Q%2.2X", value);

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Evaluating %s", object_name));

	acpi_evaluate_object(ec->handle, object_name, NULL, NULL);
}

static u32 acpi_ec_gpe_handler(void *data)
{
	acpi_status status = AE_OK;
	u8 value;
	struct acpi_ec *ec = data;

	atomic_inc(&ec->event_count);

	if (acpi_ec_mode == EC_INTR) {
		wake_up(&ec->wait);
	}

	value = acpi_ec_read_status(ec);
	if ((value & ACPI_EC_FLAG_SCI) && !atomic_read(&ec->query_pending)) {
		atomic_set(&ec->query_pending, 1);
		status =
		    acpi_os_execute(OSL_EC_BURST_HANDLER, acpi_ec_gpe_query,
				    ec);
	}

	return status == AE_OK ?
	    ACPI_INTERRUPT_HANDLED : ACPI_INTERRUPT_NOT_HANDLED;
}

/* --------------------------------------------------------------------------
                             Address Space Management
   -------------------------------------------------------------------------- */

static acpi_status
acpi_ec_space_setup(acpi_handle region_handle,
		    u32 function, void *handler_context, void **return_context)
{
	/*
	 * The EC object is in the handler context and is needed
	 * when calling the acpi_ec_space_handler.
	 */
	*return_context = (function != ACPI_REGION_DEACTIVATE) ?
	    handler_context : NULL;

	return AE_OK;
}

static acpi_status
acpi_ec_space_handler(u32 function, acpi_physical_address address,
		      u32 bits, acpi_integer *value,
		      void *handler_context, void *region_context)
{
	struct acpi_ec *ec = handler_context;
	int result = 0, i = 0;
	u8 temp = 0;

	if ((address > 0xFF) || !value || !handler_context)
		return AE_BAD_PARAMETER;

	if (function != ACPI_READ && function != ACPI_WRITE)
		return AE_BAD_PARAMETER;

	if (bits != 8 && acpi_strict)
		return AE_BAD_PARAMETER;

	while (bits - i > 0) {
		if (function == ACPI_READ) {
			result = acpi_ec_read(ec, address, &temp);
			(*value) |= ((acpi_integer)temp) << i;
		} else {
			temp = 0xff & ((*value) >> i);
			result = acpi_ec_write(ec, address, temp);
		}
		i += 8;
		++address;
	}

	switch (result) {
	case -EINVAL:
		return AE_BAD_PARAMETER;
		break;
	case -ENODEV:
		return AE_NOT_FOUND;
		break;
	case -ETIME:
		return AE_TIME;
		break;
	default:
		return AE_OK;
	}
}

/* --------------------------------------------------------------------------
                              FS Interface (/proc)
   -------------------------------------------------------------------------- */

static struct proc_dir_entry *acpi_ec_dir;

static int acpi_ec_read_info(struct seq_file *seq, void *offset)
{
	struct acpi_ec *ec = seq->private;

	if (!ec)
		goto end;

	seq_printf(seq, "gpe:\t\t\t0x%02x\n", (u32) ec->gpe);
	seq_printf(seq, "ports:\t\t\t0x%02x, 0x%02x\n",
		   (unsigned)ec->command_addr, (unsigned)ec->data_addr);
	seq_printf(seq, "use global lock:\t%s\n",
		   ec->global_lock ? "yes" : "no");
      end:
	return 0;
}

static int acpi_ec_info_open_fs(struct inode *inode, struct file *file)
{
	return single_open(file, acpi_ec_read_info, PDE(inode)->data);
}

static struct file_operations acpi_ec_info_ops = {
	.open = acpi_ec_info_open_fs,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release,
	.owner = THIS_MODULE,
};

static int acpi_ec_add_fs(struct acpi_device *device)
{
	struct proc_dir_entry *entry = NULL;

	if (!acpi_device_dir(device)) {
		acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device),
						     acpi_ec_dir);
		if (!acpi_device_dir(device))
			return -ENODEV;
	}

	entry = create_proc_entry(ACPI_EC_FILE_INFO, S_IRUGO,
				  acpi_device_dir(device));
	if (!entry)
		return -ENODEV;
	else {
		entry->proc_fops = &acpi_ec_info_ops;
		entry->data = acpi_driver_data(device);
		entry->owner = THIS_MODULE;
	}

	return 0;
}

static int acpi_ec_remove_fs(struct acpi_device *device)
{

	if (acpi_device_dir(device)) {
		remove_proc_entry(ACPI_EC_FILE_INFO, acpi_device_dir(device));
		remove_proc_entry(acpi_device_bid(device), acpi_ec_dir);
		acpi_device_dir(device) = NULL;
	}

	return 0;
}

/* --------------------------------------------------------------------------
                               Driver Interface
   -------------------------------------------------------------------------- */
static acpi_status
ec_parse_io_ports(struct acpi_resource *resource, void *context);

static acpi_status
ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval);

static struct acpi_ec *make_acpi_ec(void)
{
	struct acpi_ec *ec = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);
	if (!ec)
		return NULL;

	atomic_set(&ec->query_pending, 1);
	atomic_set(&ec->event_count, 1);
	mutex_init(&ec->lock);
	init_waitqueue_head(&ec->wait);

	return ec;
}

static int acpi_ec_add(struct acpi_device *device)
{
	acpi_status status = AE_OK;
	struct acpi_ec *ec = NULL;

	if (!device)
		return -EINVAL;

	strcpy(acpi_device_name(device), ACPI_EC_DEVICE_NAME);
	strcpy(acpi_device_class(device), ACPI_EC_CLASS);

	ec = make_acpi_ec();
	if (!ec)
		return -ENOMEM;

	status = ec_parse_device(device->handle, 0, ec, NULL);
	if (status != AE_CTRL_TERMINATE) {
		kfree(ec);
		return -EINVAL;
	}

	/* Check if we found the boot EC */
	if (boot_ec) {
		if (boot_ec->gpe == ec->gpe) {
			/* We might have incorrect info for GL at boot time */
			mutex_lock(&boot_ec->lock);
			boot_ec->global_lock = ec->global_lock;
			mutex_unlock(&boot_ec->lock);
			kfree(ec);
			ec = boot_ec;
		}
	} else
		first_ec = ec;
	ec->handle = device->handle;
	acpi_driver_data(device) = ec;

	acpi_ec_add_fs(device);

	return 0;
}

static int acpi_ec_remove(struct acpi_device *device, int type)
{
	struct acpi_ec *ec;

	if (!device)
		return -EINVAL;

	ec = acpi_driver_data(device);
	acpi_ec_remove_fs(device);
	acpi_driver_data(device) = NULL;
	if (ec == first_ec)
		first_ec = NULL;

	/* Don't touch boot EC */
	if (boot_ec != ec)
		kfree(ec);
	return 0;
}

static acpi_status
ec_parse_io_ports(struct acpi_resource *resource, void *context)
{
	struct acpi_ec *ec = context;

	if (resource->type != ACPI_RESOURCE_TYPE_IO)
		return AE_OK;

	/*
	 * The first address region returned is the data port, and
	 * the second address region returned is the status/command
	 * port.
	 */
	if (ec->data_addr == 0)
		ec->data_addr = resource->data.io.minimum;
	else if (ec->command_addr == 0)
		ec->command_addr = resource->data.io.minimum;
	else
		return AE_CTRL_TERMINATE;

	return AE_OK;
}

static int ec_install_handlers(struct acpi_ec *ec)
{
	acpi_status status;
	status = acpi_install_gpe_handler(NULL, ec->gpe,
					  ACPI_GPE_EDGE_TRIGGERED,
					  &acpi_ec_gpe_handler, ec);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	acpi_set_gpe_type(NULL, ec->gpe, ACPI_GPE_TYPE_RUNTIME);
	acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);

	status = acpi_install_address_space_handler(ec->handle,
						    ACPI_ADR_SPACE_EC,
						    &acpi_ec_space_handler,
						    &acpi_ec_space_setup, ec);
	if (ACPI_FAILURE(status)) {
		acpi_remove_gpe_handler(NULL, ec->gpe, &acpi_ec_gpe_handler);
		return -ENODEV;
	}

	/* EC is fully operational, allow queries */
	atomic_set(&ec->query_pending, 0);

	return 0;
}

static int acpi_ec_start(struct acpi_device *device)
{
	struct acpi_ec *ec;

	if (!device)
		return -EINVAL;

	ec = acpi_driver_data(device);

	if (!ec)
		return -EINVAL;

	/* Boot EC is already working */
	if (ec == boot_ec)
		return 0;

	return ec_install_handlers(ec);
}

static int acpi_ec_stop(struct acpi_device *device, int type)
{
	acpi_status status;
	struct acpi_ec *ec;

	if (!device)
		return -EINVAL;

	ec = acpi_driver_data(device);
	if (!ec)
		return -EINVAL;

	/* Don't touch boot EC */
	if (ec == boot_ec)
		return 0;

	status = acpi_remove_address_space_handler(ec->handle,
						   ACPI_ADR_SPACE_EC,
						   &acpi_ec_space_handler);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	status = acpi_remove_gpe_handler(NULL, ec->gpe, &acpi_ec_gpe_handler);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	return 0;
}

static acpi_status
ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
{
	acpi_status status;

	struct acpi_ec *ec = context;
	status = acpi_walk_resources(handle, METHOD_NAME__CRS,
				     ec_parse_io_ports, ec);
	if (ACPI_FAILURE(status))
		return status;

	/* Get GPE bit assignment (EC events). */
	/* TODO: Add support for _GPE returning a package */
	status = acpi_evaluate_integer(handle, "_GPE", NULL, &ec->gpe);
	if (ACPI_FAILURE(status))
		return status;

	/* Use the global lock for all EC transactions? */
	acpi_evaluate_integer(handle, "_GLK", NULL, &ec->global_lock);

	ec->handle = handle;

	printk(KERN_INFO PREFIX "GPE = 0x%lx, I/O: command/status = 0x%lx, data = 0x%lx",
			  ec->gpe, ec->command_addr, ec->data_addr);

	return AE_CTRL_TERMINATE;
}

int __init acpi_ec_ecdt_probe(void)
{
	int ret;
	acpi_status status;
	struct acpi_table_ecdt *ecdt_ptr;

	boot_ec = make_acpi_ec();
	if (!boot_ec)
		return -ENOMEM;
	/*
	 * Generate a boot ec context
	 */

	status = acpi_get_table(ACPI_SIG_ECDT, 1,
				(struct acpi_table_header **)&ecdt_ptr);
	if (ACPI_FAILURE(status))
		goto error;

	printk(KERN_INFO PREFIX "EC description table is found, configuring boot EC\n");

	boot_ec->command_addr = ecdt_ptr->control.address;
	boot_ec->data_addr = ecdt_ptr->data.address;
	boot_ec->gpe = ecdt_ptr->gpe;
	boot_ec->handle = ACPI_ROOT_OBJECT;

	ret = ec_install_handlers(boot_ec);
	if (!ret) {
		first_ec = boot_ec;
		return 0;
	}
      error:
	kfree(boot_ec);
	boot_ec = NULL;

	return -ENODEV;
}

static int __init acpi_ec_init(void)
{
	int result = 0;

	if (acpi_disabled)
		return 0;

	acpi_ec_dir = proc_mkdir(ACPI_EC_CLASS, acpi_root_dir);
	if (!acpi_ec_dir)
		return -ENODEV;

	/* Now register the driver for the EC */
	result = acpi_bus_register_driver(&acpi_ec_driver);
	if (result < 0) {
		remove_proc_entry(ACPI_EC_CLASS, acpi_root_dir);
		return -ENODEV;
	}

	return result;
}

subsys_initcall(acpi_ec_init);

/* EC driver currently not unloadable */
#if 0
static void __exit acpi_ec_exit(void)
{

	acpi_bus_unregister_driver(&acpi_ec_driver);

	remove_proc_entry(ACPI_EC_CLASS, acpi_root_dir);

	return;
}
#endif				/* 0 */

static int __init acpi_ec_set_intr_mode(char *str)
{
	int intr;

	if (!get_option(&str, &intr))
		return 0;

	acpi_ec_mode = (intr) ? EC_INTR : EC_POLL;

	printk(KERN_NOTICE PREFIX "%s mode.\n", intr ? "interrupt" : "polling");

	return 1;
}

__setup("ec_intr=", acpi_ec_set_intr_mode);