/* 
   *   Creation Date: <2003/03/14 20:54:13 samuel>
   *   Time-stamp: <2004/03/20 14:20:59 samuel>
   *   
   *	<therm_windtunnel.c>
   *	
   *	The G4 "windtunnel" has a single fan controlled by an
   *	ADM1030 fan controller and a DS1775 thermostat.
   *
   *	The fan controller is equipped with a temperature sensor
   *	which measures the case temperature. The DS1775 sensor
   *	measures the CPU temperature. This driver tunes the
   *	behavior of the fan. It is based upon empirical observations
   *	of the 'AppleFan' driver under Mac OS X.
   *
   *	WARNING: This driver has only been testen on Apple's
   *	1.25 MHz Dual G4 (March 03). It is tuned for a CPU

   *	temperature around 57 C.

   *
   *   Copyright (C) 2003, 2004 Samuel Rydh (samuel@ibrium.se)
   *
   *   Loosely based upon 'thermostat.c' written by Benjamin Herrenschmidt
   *   
   *   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
   *   
   */

  #include <linux/types.h>
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/kernel.h>
  #include <linux/delay.h>
  #include <linux/sched.h>
  #include <linux/i2c.h>

  #include <linux/init.h>

  #include <linux/kthread.h>

  #include <linux/of_platform.h>

  #include <asm/prom.h>
  #include <asm/machdep.h>
  #include <asm/io.h>
  #include <asm/system.h>
  #include <asm/sections.h>

  #include <asm/macio.h>

  #define LOG_TEMP		0			/* continuously log temperature */

  static struct {
  	volatile int		running;

  	struct task_struct	*poll_task;

  	struct mutex	 	lock;

  	struct platform_device	*of_dev;

  	
  	struct i2c_client	*thermostat;
  	struct i2c_client	*fan;
  
  	int			overheat_temp;		/* 100% fan at this temp */
  	int			overheat_hyst;
  	int			temp;
  	int			casetemp;
  	int			fan_level;		/* active fan_table setting */
  
  	int			downind;
  	int			upind;
  
  	int			r0, r1, r20, r23, r25;	/* saved register */
  } x;
  
  #define T(x,y)			(((x)<<8) | (y)*0x100/10 )
  
  static struct {
  	int			fan_down_setting;
  	int			temp;
  	int			fan_up_setting;
  } fan_table[] = {
  	{ 11, T(0,0),  11 },	/* min fan */
  	{ 11, T(55,0), 11 },
  	{  6, T(55,3), 11 },
  	{  7, T(56,0), 11 },
  	{  8, T(57,0), 8 },
  	{  7, T(58,3), 7 },
  	{  6, T(58,8), 6 },
  	{  5, T(59,2), 5 },
  	{  4, T(59,6), 4 },
  	{  3, T(59,9), 3 },
  	{  2, T(60,1), 2 },
  	{  1, 0xfffff, 1 }	/* on fire */
  };
  
  static void
  print_temp( const char *s, int temp )
  {
  	printk("%s%d.%d C", s ? s : "", temp>>8, (temp & 255)*10/256 );
  }
  
  static ssize_t

  show_cpu_temperature( struct device *dev, struct device_attribute *attr, char *buf )

  {
  	return sprintf(buf, "%d.%d
  ", x.temp>>8, (x.temp & 255)*10/256 );
  }
  
  static ssize_t

  show_case_temperature( struct device *dev, struct device_attribute *attr, char *buf )

  {
  	return sprintf(buf, "%d.%d
  ", x.casetemp>>8, (x.casetemp & 255)*10/256 );
  }
  
  static DEVICE_ATTR(cpu_temperature, S_IRUGO, show_cpu_temperature, NULL );
  static DEVICE_ATTR(case_temperature, S_IRUGO, show_case_temperature, NULL );
  
  
  
  /************************************************************************/
  /*	controller thread						*/
  /************************************************************************/
  
  static int
  write_reg( struct i2c_client *cl, int reg, int data, int len )
  {
  	u8 tmp[3];
  
  	if( len < 1 || len > 2 || data < 0 )
  		return -EINVAL;
  
  	tmp[0] = reg;
  	tmp[1] = (len == 1) ? data : (data >> 8);
  	tmp[2] = data;
  	len++;
  	
  	if( i2c_master_send(cl, tmp, len) != len )
  		return -ENODEV;
  	return 0;
  }
  
  static int
  read_reg( struct i2c_client *cl, int reg, int len )
  {
  	u8 buf[2];
  
  	if( len != 1 && len != 2 )
  		return -EINVAL;
  	buf[0] = reg;
  	if( i2c_master_send(cl, buf, 1) != 1 )
  		return -ENODEV;
  	if( i2c_master_recv(cl, buf, len) != len )
  		return -ENODEV;
  	return (len == 2)? ((unsigned int)buf[0] << 8) | buf[1] : buf[0];
  }
  
  static void
  tune_fan( int fan_setting )
  {
  	int val = (fan_setting << 3) | 7;
  
  	/* write_reg( x.fan, 0x24, val, 1 ); */
  	write_reg( x.fan, 0x25, val, 1 );
  	write_reg( x.fan, 0x20, 0, 1 );
  	print_temp("CPU-temp: ", x.temp );
  	if( x.casetemp )
  		print_temp(", Case: ", x.casetemp );
  	printk(",  Fan: %d (tuned %+d)
  ", 11-fan_setting, x.fan_level-fan_setting );
  
  	x.fan_level = fan_setting;
  }
  
  static void
  poll_temp( void )
  {
  	int temp, i, level, casetemp;
  
  	temp = read_reg( x.thermostat, 0, 2 );
  
  	/* this actually occurs when the computer is loaded */
  	if( temp < 0 )
  		return;
  
  	casetemp = read_reg(x.fan, 0x0b, 1) << 8;
  	casetemp |= (read_reg(x.fan, 0x06, 1) & 0x7) << 5;
  
  	if( LOG_TEMP && x.temp != temp ) {
  		print_temp("CPU-temp: ", temp );
  		print_temp(", Case: ", casetemp );
  		printk(",  Fan: %d
  ", 11-x.fan_level );
  	}
  	x.temp = temp;
  	x.casetemp = casetemp;
  
  	level = -1;
  	for( i=0; (temp & 0xffff) > fan_table[i].temp ; i++ )
  		;
  	if( i < x.downind )
  		level = fan_table[i].fan_down_setting;
  	x.downind = i;
  
  	for( i=0; (temp & 0xffff) >= fan_table[i+1].temp ; i++ )
  		;
  	if( x.upind < i )
  		level = fan_table[i].fan_up_setting;
  	x.upind = i;
  
  	if( level >= 0 )
  		tune_fan( level );
  }
  
  
  static void
  setup_hardware( void )
  {
  	int val;

  	int err;

  
  	/* save registers (if we unload the module) */
  	x.r0 = read_reg( x.fan, 0x00, 1 );
  	x.r1 = read_reg( x.fan, 0x01, 1 );
  	x.r20 = read_reg( x.fan, 0x20, 1 );
  	x.r23 = read_reg( x.fan, 0x23, 1 );
  	x.r25 = read_reg( x.fan, 0x25, 1 );
  
  	/* improve measurement resolution (convergence time 1.5s) */
  	if( (val=read_reg(x.thermostat, 1, 1)) >= 0 ) {
  		val |= 0x60;
  		if( write_reg( x.thermostat, 1, val, 1 ) )
  			printk("Failed writing config register
  ");
  	}
  	/* disable interrupts and TAC input */
  	write_reg( x.fan, 0x01, 0x01, 1 );
  	/* enable filter */
  	write_reg( x.fan, 0x23, 0x91, 1 );
  	/* remote temp. controls fan */
  	write_reg( x.fan, 0x00, 0x95, 1 );
  
  	/* The thermostat (which besides measureing temperature controls
  	 * has a THERM output which puts the fan on 100%) is usually
  	 * set to kick in at 80 C (chip default). We reduce this a bit
  	 * to be on the safe side (OSX doesn't)...
  	 */
  	if( x.overheat_temp == (80 << 8) ) {

  		x.overheat_temp = 75 << 8;
  		x.overheat_hyst = 70 << 8;

  		write_reg( x.thermostat, 2, x.overheat_hyst, 2 );
  		write_reg( x.thermostat, 3, x.overheat_temp, 2 );
  
  		print_temp("Reducing overheating limit to ", x.overheat_temp );
  		print_temp(" (Hyst: ", x.overheat_hyst );
  		printk(")
  ");
  	}
  
  	/* set an initial fan setting */
  	x.downind = 0xffff;
  	x.upind = -1;
  	/* tune_fan( fan_up_table[x.upind].fan_setting ); */

  	err = device_create_file( &x.of_dev->dev, &dev_attr_cpu_temperature );
  	err |= device_create_file( &x.of_dev->dev, &dev_attr_case_temperature );
  	if (err)
  		printk(KERN_WARNING
  			"Failed to create temperature attribute file(s).
  ");

  }
  
  static void
  restore_regs( void )
  {
  	device_remove_file( &x.of_dev->dev, &dev_attr_cpu_temperature );
  	device_remove_file( &x.of_dev->dev, &dev_attr_case_temperature );
  
  	write_reg( x.fan, 0x01, x.r1, 1 );
  	write_reg( x.fan, 0x20, x.r20, 1 );
  	write_reg( x.fan, 0x23, x.r23, 1 );
  	write_reg( x.fan, 0x25, x.r25, 1 );
  	write_reg( x.fan, 0x00, x.r0, 1 );
  }

  static int control_loop(void *dummy)

  {

  	mutex_lock(&x.lock);

  	setup_hardware();

  	mutex_unlock(&x.lock);

  	for (;;) {

  		msleep_interruptible(8000);

  		if (kthread_should_stop())
  			break;

  		mutex_lock(&x.lock);

  		poll_temp();

  		mutex_unlock(&x.lock);

  	}

  	mutex_lock(&x.lock);

  	restore_regs();

  	mutex_unlock(&x.lock);

  	return 0;

  }
  
  
  /************************************************************************/
  /*	i2c probing and setup						*/
  /************************************************************************/
  
  static int
  do_attach( struct i2c_adapter *adapter )
  {

  	/* scan 0x48-0x4f (DS1775) and 0x2c-2x2f (ADM1030) */
  	static const unsigned short scan_ds1775[] = {
  		0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
  		I2C_CLIENT_END
  	};
  	static const unsigned short scan_adm1030[] = {
  		0x2c, 0x2d, 0x2e, 0x2f,
  		I2C_CLIENT_END
  	};

  
  	if( strncmp(adapter->name, "uni-n", 5) )
  		return 0;
  
  	if( !x.running ) {

  		struct i2c_board_info info;
  
  		memset(&info, 0, sizeof(struct i2c_board_info));
  		strlcpy(info.type, "therm_ds1775", I2C_NAME_SIZE);

  		i2c_new_probed_device(adapter, &info, scan_ds1775, NULL);

  
  		strlcpy(info.type, "therm_adm1030", I2C_NAME_SIZE);

  		i2c_new_probed_device(adapter, &info, scan_adm1030, NULL);

  		if( x.thermostat && x.fan ) {
  			x.running = 1;

  			x.poll_task = kthread_run(control_loop, NULL, "g4fand");

  		}
  	}

  	return 0;

  }
  
  static int

  do_remove(struct i2c_client *client)

  {

  	if (x.running) {
  		x.running = 0;
  		kthread_stop(x.poll_task);
  		x.poll_task = NULL;

  	}

  	if (client == x.thermostat)
  		x.thermostat = NULL;
  	else if (client == x.fan)
  		x.fan = NULL;
  	else
  		printk(KERN_ERR "g4fan: bad client
  ");

  	return 0;
  }

  
  static int
  attach_fan( struct i2c_client *cl )
  {
  	if( x.fan )
  		goto out;
  
  	/* check that this is an ADM1030 */
  	if( read_reg(cl, 0x3d, 1) != 0x30 || read_reg(cl, 0x3e, 1) != 0x41 )
  		goto out;
  	printk("ADM1030 fan controller [@%02x]
  ", cl->addr );

  	x.fan = cl;

   out:

  	return 0;
  }
  
  static int
  attach_thermostat( struct i2c_client *cl ) 
  {
  	int hyst_temp, os_temp, temp;
  
  	if( x.thermostat )
  		goto out;
  
  	if( (temp=read_reg(cl, 0, 2)) < 0 )
  		goto out;
  	
  	/* temperature sanity check */
  	if( temp < 0x1600 || temp > 0x3c00 )
  		goto out;
  	hyst_temp = read_reg(cl, 2, 2);
  	os_temp = read_reg(cl, 3, 2);
  	if( hyst_temp < 0 || os_temp < 0 )
  		goto out;
  
  	printk("DS1775 digital thermometer [@%02x]
  ", cl->addr );
  	print_temp("Temp: ", temp );
  	print_temp("  Hyst: ", hyst_temp );
  	print_temp("  OS: ", os_temp );
  	printk("
  ");
  
  	x.temp = temp;
  	x.overheat_temp = os_temp;
  	x.overheat_hyst = hyst_temp;

  	x.thermostat = cl;

  out:

  	return 0;
  }

  enum chip { ds1775, adm1030 };
  
  static const struct i2c_device_id therm_windtunnel_id[] = {
  	{ "therm_ds1775", ds1775 },
  	{ "therm_adm1030", adm1030 },
  	{ }
  };

  static int

  do_probe(struct i2c_client *cl, const struct i2c_device_id *id)

  {

  	struct i2c_adapter *adapter = cl->adapter;

  
  	if( !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA
  				     | I2C_FUNC_SMBUS_WRITE_BYTE) )
  		return 0;

  	switch (id->driver_data) {
  	case adm1030:

  		return attach_fan( cl );

  	case ds1775:
  		return attach_thermostat(cl);
  	}
  	return 0;

  }

  static struct i2c_driver g4fan_driver = {
  	.driver = {
  		.name	= "therm_windtunnel",
  	},
  	.attach_adapter = do_attach,
  	.probe		= do_probe,
  	.remove		= do_remove,
  	.id_table	= therm_windtunnel_id,
  };

  
  /************************************************************************/
  /*	initialization / cleanup					*/
  /************************************************************************/

  static int therm_of_probe(struct platform_device *dev)

  {
  	return i2c_add_driver( &g4fan_driver );
  }
  
  static int

  therm_of_remove( struct platform_device *dev )

  {

  	i2c_del_driver( &g4fan_driver );
  	return 0;

  }

  static const struct of_device_id therm_of_match[] = {{

  	.name		= "fan",

  	.compatible	= "adm1030"
      }, {}
  };

  static struct platform_driver therm_of_driver = {

  	.driver = {
  		.name = "temperature",
  		.owner = THIS_MODULE,
  		.of_match_table = therm_of_match,
  	},

  	.probe		= therm_of_probe,
  	.remove		= therm_of_remove,
  };
  
  struct apple_thermal_info {
  	u8		id;			/* implementation ID */
  	u8		fan_count;		/* number of fans */
  	u8		thermostat_count;	/* number of thermostats */
  	u8		unused;
  };
  
  static int __init
  g4fan_init( void )
  {

  	const struct apple_thermal_info *info;

  	struct device_node *np;

  	mutex_init(&x.lock);

  
  	if( !(np=of_find_node_by_name(NULL, "power-mgt")) )
  		return -ENODEV;

  	info = of_get_property(np, "thermal-info", NULL);

  	of_node_put(np);

  	if( !info || !of_machine_is_compatible("PowerMac3,6") )

  		return -ENODEV;
  
  	if( info->id != 3 ) {
  		printk(KERN_ERR "therm_windtunnel: unsupported thermal design %d
  ", info->id );
  		return -ENODEV;
  	}
  	if( !(np=of_find_node_by_name(NULL, "fan")) )
  		return -ENODEV;

  	x.of_dev = of_platform_device_create(np, "temperature", NULL);

  	of_node_put( np );
  
  	if( !x.of_dev ) {
  		printk(KERN_ERR "Can't register fan controller!
  ");
  		return -ENODEV;
  	}

  	platform_driver_register( &therm_of_driver );

  	return 0;
  }
  
  static void __exit
  g4fan_exit( void )
  {

  	platform_driver_unregister( &therm_of_driver );

  
  	if( x.of_dev )
  		of_device_unregister( x.of_dev );
  }
  
  module_init(g4fan_init);
  module_exit(g4fan_exit);
  
  MODULE_AUTHOR("Samuel Rydh <samuel@ibrium.se>");
  MODULE_DESCRIPTION("Apple G4 (windtunnel) fan controller");
  MODULE_LICENSE("GPL");