/*
   * 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>
  #include <linux/slab.h>
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("System voltages control via Attansic ATXP1");
  MODULE_VERSION("0.6.3");
  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 };
  
  static int atxp1_probe(struct i2c_client *client,
  		       const struct i2c_device_id *id);
  static int atxp1_remove(struct i2c_client *client);
  static struct atxp1_data *atxp1_update_device(struct device *dev);
  static int atxp1_detect(struct i2c_client *client, struct i2c_board_info *info);
  
  static const struct i2c_device_id atxp1_id[] = {
  	{ "atxp1", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, atxp1_id);
  
  static struct i2c_driver atxp1_driver = {
  	.class		= I2C_CLASS_HWMON,
  	.driver = {
  		.name	= "atxp1",
  	},
  	.probe		= atxp1_probe,
  	.remove		= atxp1_remove,
  	.id_table	= atxp1_id,
  	.detect		= atxp1_detect,
  	.address_list	= normal_i2c,
  };
  
  struct atxp1_data {
  	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 long vcore;
  	int err;
  
  	client = to_i2c_client(dev);
  	data = atxp1_update_device(dev);
  
  	err = kstrtoul(buf, 10, &vcore);
  	if (err)
  		return err;
  
  	vcore /= 25;
  	vcore *= 25;
  
  	/* Calculate VID */
  	vid = vid_to_reg(vcore, data->vrm);
  	if (vid < 0) {
  		dev_err(dev, "VID calculation failed.
  ");
  		return vid;
  	}
  
  	/*
  	 * 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)
  ", (int)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 long value;
  	int err;
  
  	client = to_i2c_client(dev);
  	data = atxp1_update_device(dev);
  
  	err = kstrtoul(buf, 16, &value);
  	if (err)
  		return err;
  
  	value &= ATXP1_GPIO1MASK;
  
  	if (value != (data->reg.gpio1 & ATXP1_GPIO1MASK)) {
  		dev_info(dev, "Writing 0x%x to GPIO1.
  ", (unsigned int)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 = atxp1_update_device(dev);
  	struct i2c_client *client = to_i2c_client(dev);
  	unsigned long value;
  	int err;
  
  	err = kstrtoul(buf, 16, &value);
  	if (err)
  		return err;
  	value &= 0xff;
  
  	if (value != data->reg.gpio2) {
  		dev_info(dev, "Writing 0x%x to GPIO1.
  ", (unsigned int)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,
  };
  
  
  /* Return 0 if detection is successful, -ENODEV otherwise */
  static int atxp1_detect(struct i2c_client *new_client,
  			struct i2c_board_info *info)
  {
  	struct i2c_adapter *adapter = new_client->adapter;
  
  	u8 temp;
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
  		return -ENODEV;
  
  	/* 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)))
  		return -ENODEV;
  
  	/*
  	 * 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)))
  		return -ENODEV;
  
  	/* Get VRM */
  	temp = vid_which_vrm();
  
  	if ((temp != 90) && (temp != 91)) {
  		dev_err(&adapter->dev, "atxp1: Not supporting VRM %d.%d
  ",
  				temp / 10, temp % 10);
  		return -ENODEV;
  	}
  
  	strlcpy(info->type, "atxp1", I2C_NAME_SIZE);
  
  	return 0;
  }
  
  static int atxp1_probe(struct i2c_client *new_client,
  		       const struct i2c_device_id *id)
  {
  	struct atxp1_data *data;
  	int err;
  
  	data = devm_kzalloc(&new_client->dev, sizeof(struct atxp1_data),
  			    GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	/* Get VRM */
  	data->vrm = vid_which_vrm();
  
  	i2c_set_clientdata(new_client, data);
  	data->valid = 0;
  
  	mutex_init(&data->update_lock);
  
  	/* Register sysfs hooks */
  	err = sysfs_create_group(&new_client->dev.kobj, &atxp1_group);
  	if (err)
  		return err;
  
  	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);
  	return err;
  };
  
  static int atxp1_remove(struct i2c_client *client)
  {
  	struct atxp1_data *data = i2c_get_clientdata(client);
  
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_group(&client->dev.kobj, &atxp1_group);
  
  	return 0;
  };
  
  module_i2c_driver(atxp1_driver);