/*
      atxp1.c - kernel module for setting CPU VID and general purpose
                       I/Os using the Attansic ATXP1 chip.
  
      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., 675 Mass Ave, Cambridge, MA 02139, USA.
  
  */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>

  #include <linux/jiffies.h>

  #include <linux/i2c.h>

  #include <linux/hwmon.h>

  #include <linux/hwmon-vid.h>

  #include <linux/err.h>

  #include <linux/mutex.h>

  #include <linux/sysfs.h>

  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("System voltages control via Attansic ATXP1");
  MODULE_VERSION("0.6.2");
  MODULE_AUTHOR("Sebastian Witt <se.witt@gmx.net>");
  
  #define ATXP1_VID	0x00
  #define ATXP1_CVID	0x01
  #define ATXP1_GPIO1	0x06
  #define ATXP1_GPIO2	0x0a
  #define ATXP1_VIDENA	0x20
  #define ATXP1_VIDMASK	0x1f
  #define ATXP1_GPIO1MASK	0x0f

  static const unsigned short normal_i2c[] = { 0x37, 0x4e, I2C_CLIENT_END };

  I2C_CLIENT_INSMOD_1(atxp1);

  
  static int atxp1_attach_adapter(struct i2c_adapter * adapter);
  static int atxp1_detach_client(struct i2c_client * client);
  static struct atxp1_data * atxp1_update_device(struct device *dev);
  static int atxp1_detect(struct i2c_adapter *adapter, int address, int kind);
  
  static struct i2c_driver atxp1_driver = {

  	.driver = {

  		.name	= "atxp1",
  	},

  	.attach_adapter = atxp1_attach_adapter,
  	.detach_client	= atxp1_detach_client,
  };
  
  struct atxp1_data {
  	struct i2c_client client;

  	struct device *hwmon_dev;

  	struct mutex update_lock;

  	unsigned long last_updated;
  	u8 valid;
  	struct {
  		u8 vid;		/* VID output register */
  		u8 cpu_vid; /* VID input from CPU */
  		u8 gpio1;   /* General purpose I/O register 1 */
  		u8 gpio2;   /* General purpose I/O register 2 */
  	} reg;
  	u8 vrm;			/* Detected CPU VRM */
  };
  
  static struct atxp1_data * atxp1_update_device(struct device *dev)
  {
  	struct i2c_client *client;
  	struct atxp1_data *data;
  
  	client = to_i2c_client(dev);
  	data = i2c_get_clientdata(client);

  	mutex_lock(&data->update_lock);

  	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {

  
  		/* Update local register data */
  		data->reg.vid = i2c_smbus_read_byte_data(client, ATXP1_VID);
  		data->reg.cpu_vid = i2c_smbus_read_byte_data(client, ATXP1_CVID);
  		data->reg.gpio1 = i2c_smbus_read_byte_data(client, ATXP1_GPIO1);
  		data->reg.gpio2 = i2c_smbus_read_byte_data(client, ATXP1_GPIO2);
  
  		data->valid = 1;
  	}

  	mutex_unlock(&data->update_lock);

  
  	return(data);
  }
  
  /* sys file functions for cpu0_vid */

  static ssize_t atxp1_showvcore(struct device *dev, struct device_attribute *attr, char *buf)

  {
  	int size;
  	struct atxp1_data *data;
  
  	data = atxp1_update_device(dev);
  
  	size = sprintf(buf, "%d
  ", vid_from_reg(data->reg.vid & ATXP1_VIDMASK, data->vrm));
  
  	return size;
  }

  static ssize_t atxp1_storevcore(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)

  {
  	struct atxp1_data *data;
  	struct i2c_client *client;

  	int vid, cvid;

  	unsigned int vcore;
  
  	client = to_i2c_client(dev);
  	data = atxp1_update_device(dev);
  
  	vcore = simple_strtoul(buf, NULL, 10);
  	vcore /= 25;
  	vcore *= 25;
  
  	/* Calculate VID */
  	vid = vid_to_reg(vcore, data->vrm);
  
  	if (vid < 0) {
  		dev_err(dev, "VID calculation failed.
  ");
  		return -1;
  	}
  
  	/* If output enabled, use control register value. Otherwise original CPU VID */
  	if (data->reg.vid & ATXP1_VIDENA)
  		cvid = data->reg.vid & ATXP1_VIDMASK;
  	else
  		cvid = data->reg.cpu_vid;
  
  	/* Nothing changed, aborting */
  	if (vid == cvid)
  		return count;

  	dev_dbg(dev, "Setting VCore to %d mV (0x%02x)
  ", vcore, vid);

  
  	/* Write every 25 mV step to increase stability */
  	if (cvid > vid) {
  		for (; cvid >= vid; cvid--) {
          		i2c_smbus_write_byte_data(client, ATXP1_VID, cvid | ATXP1_VIDENA);
  		}
  	}
  	else {
  		for (; cvid <= vid; cvid++) {
          		i2c_smbus_write_byte_data(client, ATXP1_VID, cvid | ATXP1_VIDENA);
  		}
  	}
  
  	data->valid = 0;
  
  	return count;
  }
  
  /* CPU core reference voltage
      unit: millivolt
  */
  static DEVICE_ATTR(cpu0_vid, S_IRUGO | S_IWUSR, atxp1_showvcore, atxp1_storevcore);
  
  /* sys file functions for GPIO1 */

  static ssize_t atxp1_showgpio1(struct device *dev, struct device_attribute *attr, char *buf)

  {
  	int size;
  	struct atxp1_data *data;
  
  	data = atxp1_update_device(dev);
  
  	size = sprintf(buf, "0x%02x
  ", data->reg.gpio1 & ATXP1_GPIO1MASK);
  
  	return size;
  }

  static ssize_t atxp1_storegpio1(struct device *dev, struct device_attribute *attr, const char*buf, size_t count)

  {
  	struct atxp1_data *data;
  	struct i2c_client *client;
  	unsigned int value;
  
  	client = to_i2c_client(dev);
  	data = atxp1_update_device(dev);
  
  	value = simple_strtoul(buf, NULL, 16);
  
  	value &= ATXP1_GPIO1MASK;
  
  	if (value != (data->reg.gpio1 & ATXP1_GPIO1MASK)) {
  		dev_info(dev, "Writing 0x%x to GPIO1.
  ", value);
  
  		i2c_smbus_write_byte_data(client, ATXP1_GPIO1, value);
  
  		data->valid = 0;
  	}
  
  	return count;
  }
  
  /* GPIO1 data register
      unit: Four bit as hex (e.g. 0x0f)
  */
  static DEVICE_ATTR(gpio1, S_IRUGO | S_IWUSR, atxp1_showgpio1, atxp1_storegpio1);
  
  /* sys file functions for GPIO2 */

  static ssize_t atxp1_showgpio2(struct device *dev, struct device_attribute *attr, char *buf)

  {
  	int size;
  	struct atxp1_data *data;
  
  	data = atxp1_update_device(dev);
  
  	size = sprintf(buf, "0x%02x
  ", data->reg.gpio2);
  
  	return size;
  }

  static ssize_t atxp1_storegpio2(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)

  {
  	struct atxp1_data *data;
  	struct i2c_client *client;
  	unsigned int value;
  
  	client = to_i2c_client(dev);
  	data = atxp1_update_device(dev);
  
  	value = simple_strtoul(buf, NULL, 16) & 0xff;
  
  	if (value != data->reg.gpio2) {
  		dev_info(dev, "Writing 0x%x to GPIO1.
  ", value);
  
  		i2c_smbus_write_byte_data(client, ATXP1_GPIO2, value);
  
  		data->valid = 0;
  	}
  
  	return count;
  }
  
  /* GPIO2 data register
      unit: Eight bit as hex (e.g. 0xff)
  */
  static DEVICE_ATTR(gpio2, S_IRUGO | S_IWUSR, atxp1_showgpio2, atxp1_storegpio2);

  static struct attribute *atxp1_attributes[] = {
  	&dev_attr_gpio1.attr,
  	&dev_attr_gpio2.attr,
  	&dev_attr_cpu0_vid.attr,
  	NULL
  };
  
  static const struct attribute_group atxp1_group = {
  	.attrs = atxp1_attributes,
  };

  
  static int atxp1_attach_adapter(struct i2c_adapter *adapter)
  {

  	if (!(adapter->class & I2C_CLASS_HWMON))
  		return 0;

  	return i2c_probe(adapter, &addr_data, &atxp1_detect);

  };
  
  static int atxp1_detect(struct i2c_adapter *adapter, int address, int kind)
  {
  	struct i2c_client * new_client;
  	struct atxp1_data * data;
  	int err = 0;
  	u8 temp;
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
  		goto exit;

  	if (!(data = kzalloc(sizeof(struct atxp1_data), GFP_KERNEL))) {

  		err = -ENOMEM;
  		goto exit;
  	}

  	new_client = &data->client;
  	i2c_set_clientdata(new_client, data);
  
  	new_client->addr = address;
  	new_client->adapter = adapter;
  	new_client->driver = &atxp1_driver;
  	new_client->flags = 0;
  
  	/* Detect ATXP1, checking if vendor ID registers are all zero */
  	if (!((i2c_smbus_read_byte_data(new_client, 0x3e) == 0) &&
  	     (i2c_smbus_read_byte_data(new_client, 0x3f) == 0) &&
  	     (i2c_smbus_read_byte_data(new_client, 0xfe) == 0) &&
  	     (i2c_smbus_read_byte_data(new_client, 0xff) == 0) )) {
  
  		/* No vendor ID, now checking if registers 0x10,0x11 (non-existent)
  		 * showing the same as register 0x00 */
  		temp = i2c_smbus_read_byte_data(new_client, 0x00);
  
  		if (!((i2c_smbus_read_byte_data(new_client, 0x10) == temp) &&
  			 (i2c_smbus_read_byte_data(new_client, 0x11) == temp) ))
  			goto exit_free;
  	}
  
  	/* Get VRM */

  	data->vrm = vid_which_vrm();

  
  	if ((data->vrm != 90) && (data->vrm != 91)) {
  		dev_err(&new_client->dev, "Not supporting VRM %d.%d
  ",
  				data->vrm / 10, data->vrm % 10);
  		goto exit_free;
  	}
  
  	strncpy(new_client->name, "atxp1", I2C_NAME_SIZE);
  
  	data->valid = 0;

  	mutex_init(&data->update_lock);

  
  	err = i2c_attach_client(new_client);
  
  	if (err)
  	{
  		dev_err(&new_client->dev, "Attach client error.
  ");
  		goto exit_free;
  	}

  	/* Register sysfs hooks */
  	if ((err = sysfs_create_group(&new_client->dev.kobj, &atxp1_group)))
  		goto exit_detach;

  	data->hwmon_dev = hwmon_device_register(&new_client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);

  		goto exit_remove_files;

  	}

  	dev_info(&new_client->dev, "Using VRM: %d.%d
  ",
  			 data->vrm / 10, data->vrm % 10);
  
  	return 0;

  exit_remove_files:
  	sysfs_remove_group(&new_client->dev.kobj, &atxp1_group);

  exit_detach:
  	i2c_detach_client(new_client);

  exit_free:
  	kfree(data);
  exit:
  	return err;
  };
  
  static int atxp1_detach_client(struct i2c_client * client)
  {

  	struct atxp1_data * data = i2c_get_clientdata(client);

  	int err;

  	hwmon_device_unregister(data->hwmon_dev);

  	sysfs_remove_group(&client->dev.kobj, &atxp1_group);

  	err = i2c_detach_client(client);
  
  	if (err)
  		dev_err(&client->dev, "Failed to detach client.
  ");
  	else

  		kfree(data);

  
  	return err;
  };
  
  static int __init atxp1_init(void)
  {
  	return i2c_add_driver(&atxp1_driver);
  };
  
  static void __exit atxp1_exit(void)
  {
  	i2c_del_driver(&atxp1_driver);
  };
  
  module_init(atxp1_init);
  module_exit(atxp1_exit);