text: /*
   *  acpi_ec.c - ACPI Embedded Controller Driver ($Revision: 38 $)
   *
   *  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 _COMPONENT		ACPI_EC_COMPONENT
  ACPI_MODULE_NAME("ec");
  #define ACPI_EC_COMPONENT		0x00100000
  #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 */
  static struct acpi_ec {
  	acpi_handle handle;
  	unsigned long uid;
  	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;
  	atomic_t leaving_burst;	/* 0 : No, 1 : Yes, 2: abort */
  	wait_queue_head_t wait;
  } *ec_ecdt;
  
  /* External interfaces use first EC only, so remember */
  static struct acpi_device *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)
  {
  	if (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;
  }
  
  #ifdef ACPI_FUTURE_USAGE
  /*
   * Note: samsung nv5000 doesn't work with ec burst mode.
   * http://bugzilla.kernel.org/show_bug.cgi?id=4980
   */
  int acpi_ec_enter_burst_mode(struct acpi_ec *ec)
  {
  	u8 tmp = 0;
  	u8 status = 0;
  
  	status = acpi_ec_read_status(ec);
  	if (status != -EINVAL && !(status & ACPI_EC_FLAG_BURST)) {
  		status = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0);
  		if (status)
  			goto end;
  		acpi_ec_write_cmd(ec, ACPI_EC_BURST_ENABLE);
  		status = acpi_ec_wait(ec, ACPI_EC_EVENT_OBF_1);
  		tmp = acpi_ec_read_data(ec);
  		if (tmp != 0x90) {	/* Burst ACK byte */
  			return -EINVAL;
  		}
  	}
  
  	atomic_set(&ec->leaving_burst, 0);
  	return 0;
        end:
  	ACPI_EXCEPTION((AE_INFO, status, "EC wait, burst mode"));
  	return -1;
  }
  
  int acpi_ec_leave_burst_mode(struct acpi_ec *ec)
  {
  	u8 status = 0;
  
  	status = acpi_ec_read_status(ec);
  	if (status != -EINVAL && (status & ACPI_EC_FLAG_BURST)) {
  		status = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0);
  		if (status)
  			goto end;
  		acpi_ec_write_cmd(ec, ACPI_EC_BURST_DISABLE);
  		acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0);
  	}
  	atomic_set(&ec->leaving_burst, 1);
  	return 0;
        end:
  	ACPI_EXCEPTION((AE_INFO, status, "EC leave burst mode"));
  	return -1;
  }
  #endif				/* ACPI_FUTURE_USAGE */
  
  static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, u8 command,
  					const u8 * wdata, unsigned wdata_len,
  					u8 * rdata, unsigned rdata_len)
  {
  	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);
  		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);
  		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);
  		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 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);
  	if (status) {
  		printk(KERN_DEBUG PREFIX
  		       "input buffer is not empty, aborting transaction\n");
  		goto end;
  	}
  
  	status = acpi_ec_transaction_unlocked(ec, command,
  					      wdata, wdata_len,
  					      rdata, rdata_len);
  
        end:
  
  	if (ec->global_lock)
  		acpi_release_global_lock(glk);
  	mutex_unlock(&ec->lock);
  
  	return status;
  }
  
  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);
  	*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);
  }
  
  /*
   * Externally callable EC access functions. For now, assume 1 EC only
   */
  int ec_read(u8 addr, u8 * val)
  {
  	struct acpi_ec *ec;
  	int err;
  	u8 temp_data;
  
  	if (!first_ec)
  		return -ENODEV;
  
  	ec = acpi_driver_data(first_ec);
  
  	err = acpi_ec_read(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)
  {
  	struct acpi_ec *ec;
  	int err;
  
  	if (!first_ec)
  		return -ENODEV;
  
  	ec = acpi_driver_data(first_ec);
  
  	err = acpi_ec_write(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)
  {
  	struct acpi_ec *ec;
  
  	if (!first_ec)
  		return -ENODEV;
  
  	ec = acpi_driver_data(first_ec);
  
  	return acpi_ec_transaction(ec, command, wdata,
  				   wdata_len, rdata, rdata_len);
  }
  
  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);
  	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 = (struct acpi_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 = (struct acpi_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 bit_width,
  		      acpi_integer * value,
  		      void *handler_context, void *region_context)
  {
  	int result = 0;
  	struct acpi_ec *ec = NULL;
  	u64 temp = *value;
  	acpi_integer f_v = 0;
  	int i = 0;
  
  	if ((address > 0xFF) || !value || !handler_context)
  		return AE_BAD_PARAMETER;
  
  	if (bit_width != 8 && acpi_strict) {
  		return AE_BAD_PARAMETER;
  	}
  
  	ec = (struct acpi_ec *)handler_context;
  
        next_byte:
  	switch (function) {
  	case ACPI_READ:
  		temp = 0;
  		result = acpi_ec_read(ec, (u8) address, (u8 *) & temp);
  		break;
  	case ACPI_WRITE:
  		result = acpi_ec_write(ec, (u8) address, (u8) temp);
  		break;
  	default:
  		result = -EINVAL;
  		goto out;
  		break;
  	}
  
  	bit_width -= 8;
  	if (bit_width) {
  		if (function == ACPI_READ)
  			f_v |= temp << 8 * i;
  		if (function == ACPI_WRITE)
  			temp >>= 8;
  		i++;
  		address++;
  		goto next_byte;
  	}
  
  	if (function == ACPI_READ) {
  		f_v |= temp << 8 * i;
  		*value = f_v;
  	}
  
        out:
  	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 = (struct acpi_ec *)seq->private;
  
  	if (!ec)
  		goto end;
  
  	seq_printf(seq, "gpe:                 0x%02x\n", (u32) ec->gpe);
  	seq_printf(seq, "ports:                   0x%02x, 0x%02x\n",
  		   (u32) ec->command_addr, (u32) ec->data_addr);
  	seq_printf(seq, "use global lock:         %s\n",
  		   ec->global_lock ? "yes" : "no");
  	acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
  
        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 int acpi_ec_add(struct acpi_device *device)
  {
  	int result = 0;
  	acpi_status status = AE_OK;
  	struct acpi_ec *ec = NULL;
  
  	if (!device)
  		return -EINVAL;
  
  	ec = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);
  	if (!ec)
  		return -ENOMEM;
  
  	ec->handle = device->handle;
  	ec->uid = -1;
  	mutex_init(&ec->lock);
  	atomic_set(&ec->query_pending, 0);
  	atomic_set(&ec->event_count, 1);
  	if (acpi_ec_mode == EC_INTR) {
  		atomic_set(&ec->leaving_burst, 1);
  		init_waitqueue_head(&ec->wait);
  	}
  	strcpy(acpi_device_name(device), ACPI_EC_DEVICE_NAME);
  	strcpy(acpi_device_class(device), ACPI_EC_CLASS);
  	acpi_driver_data(device) = ec;
  
  	/* Use the global lock for all EC transactions? */
  	acpi_evaluate_integer(ec->handle, "_GLK", NULL, &ec->global_lock);
  
  	/* XXX we don't test uids, because on some boxes ecdt uid = 0, see:
  	   http://bugzilla.kernel.org/show_bug.cgi?id=6111 */
  	if (ec_ecdt) {
  		acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
  						  ACPI_ADR_SPACE_EC,
  						  &acpi_ec_space_handler);
  
  		acpi_remove_gpe_handler(NULL, ec_ecdt->gpe,
  					&acpi_ec_gpe_handler);
  
  		kfree(ec_ecdt);
  	}
  
  	/* Get GPE bit assignment (EC events). */
  	/* TODO: Add support for _GPE returning a package */
  	status = acpi_evaluate_integer(ec->handle, "_GPE", NULL, &ec->gpe);
  	if (ACPI_FAILURE(status)) {
  		ACPI_EXCEPTION((AE_INFO, status,
  				"Obtaining GPE bit assignment"));
  		result = -ENODEV;
  		goto end;
  	}
  
  	result = acpi_ec_add_fs(device);
  	if (result)
  		goto end;
  
  	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "%s [%s] (gpe %d) interrupt mode.",
  			  acpi_device_name(device), acpi_device_bid(device),
  			  (u32) ec->gpe));
  
  	if (!first_ec)
  		first_ec = device;
  
        end:
  	if (result)
  		kfree(ec);
  
  	return result;
  }
  
  static int acpi_ec_remove(struct acpi_device *device, int type)
  {
  	struct acpi_ec *ec = NULL;
  
  	if (!device)
  		return -EINVAL;
  
  	ec = acpi_driver_data(device);
  
  	acpi_ec_remove_fs(device);
  
  	kfree(ec);
  
  	return 0;
  }
  
  static acpi_status
  acpi_ec_io_ports(struct acpi_resource *resource, void *context)
  {
  	struct acpi_ec *ec = (struct acpi_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 acpi_ec_start(struct acpi_device *device)
  {
  	acpi_status status = AE_OK;
  	struct acpi_ec *ec = NULL;
  
  	if (!device)
  		return -EINVAL;
  
  	ec = acpi_driver_data(device);
  
  	if (!ec)
  		return -EINVAL;
  
  	/*
  	 * Get I/O port addresses. Convert to GAS format.
  	 */
  	status = acpi_walk_resources(ec->handle, METHOD_NAME__CRS,
  				     acpi_ec_io_ports, ec);
  	if (ACPI_FAILURE(status) || ec->command_addr == 0) {
  		ACPI_EXCEPTION((AE_INFO, status,
  				"Error getting I/O port addresses"));
  		return -ENODEV;
  	}
  
  	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "gpe=0x%02lx, ports=0x%2lx,0x%2lx",
  			  ec->gpe, ec->command_addr, ec->data_addr));
  
  	/*
  	 * Install GPE handler
  	 */
  	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;
  	}
  
  	return AE_OK;
  }
  
  static int acpi_ec_stop(struct acpi_device *device, int type)
  {
  	acpi_status status = AE_OK;
  	struct acpi_ec *ec = NULL;
  
  	if (!device)
  		return -EINVAL;
  
  	ec = acpi_driver_data(device);
  
  	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 __init
  acpi_fake_ecdt_callback(acpi_handle handle,
  			u32 Level, void *context, void **retval)
  {
  	acpi_status status;
  
  	mutex_init(&ec_ecdt->lock);
  	atomic_set(&ec_ecdt->event_count, 1);
  	if (acpi_ec_mode == EC_INTR) {
  		init_waitqueue_head(&ec_ecdt->wait);
  	}
  	status = acpi_walk_resources(handle, METHOD_NAME__CRS,
  				     acpi_ec_io_ports, ec_ecdt);
  	if (ACPI_FAILURE(status))
  		return status;
  
  	ec_ecdt->uid = -1;
  	acpi_evaluate_integer(handle, "_UID", NULL, &ec_ecdt->uid);
  
  	status = acpi_evaluate_integer(handle, "_GPE", NULL, &ec_ecdt->gpe);
  	if (ACPI_FAILURE(status))
  		return status;
  	ec_ecdt->global_lock = TRUE;
  	ec_ecdt->handle = handle;
  
  	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "GPE=0x%02lx, ports=0x%2lx, 0x%2lx",
  			  ec_ecdt->gpe, ec_ecdt->command_addr,
  			  ec_ecdt->data_addr));
  
  	return AE_CTRL_TERMINATE;
  }
  
  /*
   * Some BIOS (such as some from Gateway laptops) access EC region very early
   * such as in BAT0._INI or EC._INI before an EC device is found and
   * do not provide an ECDT. According to ACPI spec, ECDT isn't mandatorily
   * required, but if EC regison is accessed early, it is required.
   * The routine tries to workaround the BIOS bug by pre-scan EC device
   * It assumes that _CRS, _HID, _GPE, _UID methods of EC don't touch any
   * op region (since _REG isn't invoked yet). The assumption is true for
   * all systems found.
   */
  static int __init acpi_ec_fake_ecdt(void)
  {
  	acpi_status status;
  	int ret = 0;
  
  	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Try to make an fake ECDT"));
  
  	ec_ecdt = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);
  	if (!ec_ecdt) {
  		ret = -ENOMEM;
  		goto error;
  	}
  
  	status = acpi_get_devices(ACPI_EC_HID,
  				  acpi_fake_ecdt_callback, NULL, NULL);
  	if (ACPI_FAILURE(status)) {
  		kfree(ec_ecdt);
  		ec_ecdt = NULL;
  		ret = -ENODEV;
  		ACPI_EXCEPTION((AE_INFO, status, "Can't make an fake ECDT"));
  		goto error;
  	}
  	return 0;
        error:
  	return ret;
  }
  
  static int __init acpi_ec_get_real_ecdt(void)
  {
  	acpi_status status;
  	struct acpi_table_ecdt *ecdt_ptr;
  
  	status = acpi_get_table(ACPI_SIG_ECDT, 1,
  				(struct acpi_table_header **)&ecdt_ptr);
  	if (ACPI_FAILURE(status))
  		return -ENODEV;
  
  	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found ECDT"));
  
  	/*
  	 * Generate a temporary ec context to use until the namespace is scanned
  	 */
  	ec_ecdt = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);
  	if (!ec_ecdt)
  		return -ENOMEM;
  
  	mutex_init(&ec_ecdt->lock);
  	atomic_set(&ec_ecdt->event_count, 1);
  	if (acpi_ec_mode == EC_INTR) {
  		init_waitqueue_head(&ec_ecdt->wait);
  	}
  	ec_ecdt->command_addr = ecdt_ptr->control.address;
  	ec_ecdt->data_addr = ecdt_ptr->data.address;
  	ec_ecdt->gpe = ecdt_ptr->gpe;
  	/* use the GL just to be safe */
  	ec_ecdt->global_lock = TRUE;
  	ec_ecdt->uid = ecdt_ptr->uid;
  
  	status = acpi_get_handle(NULL, ecdt_ptr->id, &ec_ecdt->handle);
  	if (ACPI_FAILURE(status)) {
  		goto error;
  	}
  
  	return 0;
        error:
  	ACPI_EXCEPTION((AE_INFO, status, "Could not use ECDT"));
  	kfree(ec_ecdt);
  	ec_ecdt = NULL;
  
  	return -ENODEV;
  }
  
  static int __initdata acpi_fake_ecdt_enabled;
  int __init acpi_ec_ecdt_probe(void)
  {
  	acpi_status status;
  	int ret;
  
  	ret = acpi_ec_get_real_ecdt();
  	/* Try to make a fake ECDT */
  	if (ret && acpi_fake_ecdt_enabled) {
  		ret = acpi_ec_fake_ecdt();
  	}
  
  	if (ret)
  		return 0;
  
  	/*
  	 * Install GPE handler
  	 */
  	status = acpi_install_gpe_handler(NULL, ec_ecdt->gpe,
  					  ACPI_GPE_EDGE_TRIGGERED,
  					  &acpi_ec_gpe_handler, ec_ecdt);
  	if (ACPI_FAILURE(status)) {
  		goto error;
  	}
  	acpi_set_gpe_type(NULL, ec_ecdt->gpe, ACPI_GPE_TYPE_RUNTIME);
  	acpi_enable_gpe(NULL, ec_ecdt->gpe, ACPI_NOT_ISR);
  
  	status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
  						    ACPI_ADR_SPACE_EC,
  						    &acpi_ec_space_handler,
  						    &acpi_ec_space_setup,
  						    ec_ecdt);
  	if (ACPI_FAILURE(status)) {
  		acpi_remove_gpe_handler(NULL, ec_ecdt->gpe,
  					&acpi_ec_gpe_handler);
  		goto error;
  	}
  
  	return 0;
  
        error:
  	ACPI_EXCEPTION((AE_INFO, status, "Could not use ECDT"));
  	kfree(ec_ecdt);
  	ec_ecdt = 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_fake_ecdt_setup(char *str)
  {
  	acpi_fake_ecdt_enabled = 1;
  	return 1;
  }
  
  __setup("acpi_fake_ecdt", acpi_fake_ecdt_setup);
  static int __init acpi_ec_set_intr_mode(char *str)
  {
  	int intr;
  
  	if (!get_option(&str, &intr))
  		return 0;
  
  	if (intr) {
  		acpi_ec_mode = EC_INTR;
  	} else {
  		acpi_ec_mode = EC_POLL;
  	}
  	acpi_ec_driver.ops.add = acpi_ec_add;
  	printk(KERN_NOTICE PREFIX "%s mode.\n", intr ? "interrupt" : "polling");
  
  	return 1;
  }
  
  __setup("ec_intr=", acpi_ec_set_intr_mode);
  