/*
   * SMBus driver for ACPI Embedded Controller (v0.1)
   *
   * Copyright (c) 2007 Alexey Starikovskiy
   *
   * 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 version 2.
   */
  
  #include <linux/acpi.h>
  #include <linux/wait.h>
  #include <linux/slab.h>
  #include <linux/delay.h>
  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include "sbshc.h"
  
  #define PREFIX "ACPI: "
  
  #define ACPI_SMB_HC_CLASS	"smbus_host_ctl"
  #define ACPI_SMB_HC_DEVICE_NAME	"ACPI SMBus HC"
  
  struct acpi_smb_hc {
  	struct acpi_ec *ec;
  	struct mutex lock;
  	wait_queue_head_t wait;
  	u8 offset;
  	u8 query_bit;
  	smbus_alarm_callback callback;
  	void *context;
  };
  
  static int acpi_smbus_hc_add(struct acpi_device *device);
  static int acpi_smbus_hc_remove(struct acpi_device *device);
  
  static const struct acpi_device_id sbs_device_ids[] = {
  	{"ACPI0001", 0},
  	{"ACPI0005", 0},
  	{"", 0},
  };
  
  MODULE_DEVICE_TABLE(acpi, sbs_device_ids);
  
  static struct acpi_driver acpi_smb_hc_driver = {
  	.name = "smbus_hc",
  	.class = ACPI_SMB_HC_CLASS,
  	.ids = sbs_device_ids,
  	.ops = {
  		.add = acpi_smbus_hc_add,
  		.remove = acpi_smbus_hc_remove,
  		},
  };
  
  union acpi_smb_status {
  	u8 raw;
  	struct {
  		u8 status:5;
  		u8 reserved:1;
  		u8 alarm:1;
  		u8 done:1;
  	} fields;
  };
  
  enum acpi_smb_status_codes {
  	SMBUS_OK = 0,
  	SMBUS_UNKNOWN_FAILURE = 0x07,
  	SMBUS_DEVICE_ADDRESS_NACK = 0x10,
  	SMBUS_DEVICE_ERROR = 0x11,
  	SMBUS_DEVICE_COMMAND_ACCESS_DENIED = 0x12,
  	SMBUS_UNKNOWN_ERROR = 0x13,
  	SMBUS_DEVICE_ACCESS_DENIED = 0x17,
  	SMBUS_TIMEOUT = 0x18,
  	SMBUS_HOST_UNSUPPORTED_PROTOCOL = 0x19,
  	SMBUS_BUSY = 0x1a,
  	SMBUS_PEC_ERROR = 0x1f,
  };
  
  enum acpi_smb_offset {
  	ACPI_SMB_PROTOCOL = 0,	/* protocol, PEC */
  	ACPI_SMB_STATUS = 1,	/* status */
  	ACPI_SMB_ADDRESS = 2,	/* address */
  	ACPI_SMB_COMMAND = 3,	/* command */
  	ACPI_SMB_DATA = 4,	/* 32 data registers */
  	ACPI_SMB_BLOCK_COUNT = 0x24,	/* number of data bytes */
  	ACPI_SMB_ALARM_ADDRESS = 0x25,	/* alarm address */
  	ACPI_SMB_ALARM_DATA = 0x26,	/* 2 bytes alarm data */
  };
  
  static inline int smb_hc_read(struct acpi_smb_hc *hc, u8 address, u8 *data)
  {
  	return ec_read(hc->offset + address, data);
  }
  
  static inline int smb_hc_write(struct acpi_smb_hc *hc, u8 address, u8 data)
  {
  	return ec_write(hc->offset + address, data);
  }
  
  static inline int smb_check_done(struct acpi_smb_hc *hc)
  {
  	union acpi_smb_status status = {.raw = 0};
  	smb_hc_read(hc, ACPI_SMB_STATUS, &status.raw);
  	return status.fields.done && (status.fields.status == SMBUS_OK);
  }
  
  static int wait_transaction_complete(struct acpi_smb_hc *hc, int timeout)
  {
  	if (wait_event_timeout(hc->wait, smb_check_done(hc),
  			       msecs_to_jiffies(timeout)))
  		return 0;
  	/*
  	 * After the timeout happens, OS will try to check the status of SMbus.
  	 * If the status is what OS expected, it will be regarded as the bogus
  	 * timeout.
  	 */
  	if (smb_check_done(hc))
  		return 0;
  	else
  		return -ETIME;
  }
  
  static int acpi_smbus_transaction(struct acpi_smb_hc *hc, u8 protocol,
  				  u8 address, u8 command, u8 *data, u8 length)
  {
  	int ret = -EFAULT, i;
  	u8 temp, sz = 0;
  
  	if (!hc) {
  		printk(KERN_ERR PREFIX "host controller is not configured
  ");
  		return ret;
  	}
  
  	mutex_lock(&hc->lock);
  	if (smb_hc_read(hc, ACPI_SMB_PROTOCOL, &temp))
  		goto end;
  	if (temp) {
  		ret = -EBUSY;
  		goto end;
  	}
  	smb_hc_write(hc, ACPI_SMB_COMMAND, command);
  	if (!(protocol & 0x01)) {
  		smb_hc_write(hc, ACPI_SMB_BLOCK_COUNT, length);
  		for (i = 0; i < length; ++i)
  			smb_hc_write(hc, ACPI_SMB_DATA + i, data[i]);
  	}
  	smb_hc_write(hc, ACPI_SMB_ADDRESS, address << 1);
  	smb_hc_write(hc, ACPI_SMB_PROTOCOL, protocol);
  	/*
  	 * Wait for completion. Save the status code, data size,
  	 * and data into the return package (if required by the protocol).
  	 */
  	ret = wait_transaction_complete(hc, 1000);
  	if (ret || !(protocol & 0x01))
  		goto end;
  	switch (protocol) {
  	case SMBUS_RECEIVE_BYTE:
  	case SMBUS_READ_BYTE:
  		sz = 1;
  		break;
  	case SMBUS_READ_WORD:
  		sz = 2;
  		break;
  	case SMBUS_READ_BLOCK:
  		if (smb_hc_read(hc, ACPI_SMB_BLOCK_COUNT, &sz)) {
  			ret = -EFAULT;
  			goto end;
  		}
  		sz &= 0x1f;
  		break;
  	}
  	for (i = 0; i < sz; ++i)
  		smb_hc_read(hc, ACPI_SMB_DATA + i, &data[i]);
        end:
  	mutex_unlock(&hc->lock);
  	return ret;
  }
  
  int acpi_smbus_read(struct acpi_smb_hc *hc, u8 protocol, u8 address,
  		    u8 command, u8 *data)
  {
  	return acpi_smbus_transaction(hc, protocol, address, command, data, 0);
  }
  
  EXPORT_SYMBOL_GPL(acpi_smbus_read);
  
  int acpi_smbus_write(struct acpi_smb_hc *hc, u8 protocol, u8 address,
  		     u8 command, u8 *data, u8 length)
  {
  	return acpi_smbus_transaction(hc, protocol, address, command, data, length);
  }
  
  EXPORT_SYMBOL_GPL(acpi_smbus_write);
  
  int acpi_smbus_register_callback(struct acpi_smb_hc *hc,
  			         smbus_alarm_callback callback, void *context)
  {
  	mutex_lock(&hc->lock);
  	hc->callback = callback;
  	hc->context = context;
  	mutex_unlock(&hc->lock);
  	return 0;
  }
  
  EXPORT_SYMBOL_GPL(acpi_smbus_register_callback);
  
  int acpi_smbus_unregister_callback(struct acpi_smb_hc *hc)
  {
  	mutex_lock(&hc->lock);
  	hc->callback = NULL;
  	hc->context = NULL;
  	mutex_unlock(&hc->lock);
  	return 0;
  }
  
  EXPORT_SYMBOL_GPL(acpi_smbus_unregister_callback);
  
  static inline void acpi_smbus_callback(void *context)
  {
  	struct acpi_smb_hc *hc = context;
  	if (hc->callback)
  		hc->callback(hc->context);
  }
  
  static int smbus_alarm(void *context)
  {
  	struct acpi_smb_hc *hc = context;
  	union acpi_smb_status status;
  	u8 address;
  	if (smb_hc_read(hc, ACPI_SMB_STATUS, &status.raw))
  		return 0;
  	/* Check if it is only a completion notify */
  	if (status.fields.done)
  		wake_up(&hc->wait);
  	if (!status.fields.alarm)
  		return 0;
  	mutex_lock(&hc->lock);
  	smb_hc_read(hc, ACPI_SMB_ALARM_ADDRESS, &address);
  	status.fields.alarm = 0;
  	smb_hc_write(hc, ACPI_SMB_STATUS, status.raw);
  	/* We are only interested in events coming from known devices */
  	switch (address >> 1) {
  		case ACPI_SBS_CHARGER:
  		case ACPI_SBS_MANAGER:
  		case ACPI_SBS_BATTERY:
  			acpi_os_execute(OSL_NOTIFY_HANDLER,
  					acpi_smbus_callback, hc);
  		default:;
  	}
  	mutex_unlock(&hc->lock);
  	return 0;
  }
  
  typedef int (*acpi_ec_query_func) (void *data);
  
  extern int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
  			      acpi_handle handle, acpi_ec_query_func func,
  			      void *data);
  
  static int acpi_smbus_hc_add(struct acpi_device *device)
  {
  	int status;
  	unsigned long long val;
  	struct acpi_smb_hc *hc;
  
  	if (!device)
  		return -EINVAL;
  
  	status = acpi_evaluate_integer(device->handle, "_EC", NULL, &val);
  	if (ACPI_FAILURE(status)) {
  		printk(KERN_ERR PREFIX "error obtaining _EC.
  ");
  		return -EIO;
  	}
  
  	strcpy(acpi_device_name(device), ACPI_SMB_HC_DEVICE_NAME);
  	strcpy(acpi_device_class(device), ACPI_SMB_HC_CLASS);
  
  	hc = kzalloc(sizeof(struct acpi_smb_hc), GFP_KERNEL);
  	if (!hc)
  		return -ENOMEM;
  	mutex_init(&hc->lock);
  	init_waitqueue_head(&hc->wait);
  
  	hc->ec = acpi_driver_data(device->parent);
  	hc->offset = (val >> 8) & 0xff;
  	hc->query_bit = val & 0xff;
  	device->driver_data = hc;
  
  	acpi_ec_add_query_handler(hc->ec, hc->query_bit, NULL, smbus_alarm, hc);
  	printk(KERN_INFO PREFIX "SBS HC: EC = 0x%p, offset = 0x%0x, query_bit = 0x%0x
  ",
  		hc->ec, hc->offset, hc->query_bit);
  
  	return 0;
  }
  
  extern void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit);
  
  static int acpi_smbus_hc_remove(struct acpi_device *device)
  {
  	struct acpi_smb_hc *hc;
  
  	if (!device)
  		return -EINVAL;
  
  	hc = acpi_driver_data(device);
  	acpi_ec_remove_query_handler(hc->ec, hc->query_bit);
  	kfree(hc);
  	device->driver_data = NULL;
  	return 0;
  }
  
  module_acpi_driver(acpi_smb_hc_driver);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Alexey Starikovskiy");
  MODULE_DESCRIPTION("ACPI SMBus HC driver");