/*
 * Device driver for the i2c thermostat found on the iBook G4, Albook G4
 *
 * Copyright (C) 2003, 2004 Colin Leroy, Rasmus Rohde, Benjamin Herrenschmidt
 *
 * Documentation from
 * http://www.analog.com/UploadedFiles/Data_Sheets/115254175ADT7467_pra.pdf
 * http://www.analog.com/UploadedFiles/Data_Sheets/3686221171167ADT7460_b.pdf
 *
 */

#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/slab.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/suspend.h>
#include <linux/kthread.h>
#include <linux/moduleparam.h>
#include <linux/freezer.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>

#undef DEBUG

#define CONFIG_REG   0x40
#define MANUAL_MASK  0xe0
#define AUTO_MASK    0x20
#define INVERT_MASK  0x10

static u8 TEMP_REG[3]    = {0x26, 0x25, 0x27}; /* local, sensor1, sensor2 */
static u8 LIMIT_REG[3]   = {0x6b, 0x6a, 0x6c}; /* local, sensor1, sensor2 */
static u8 MANUAL_MODE[2] = {0x5c, 0x5d};       
static u8 REM_CONTROL[2] = {0x00, 0x40};
static u8 FAN_SPEED[2]   = {0x28, 0x2a};
static u8 FAN_SPD_SET[2] = {0x30, 0x31};

static u8 default_limits_local[3] = {70, 50, 70};    /* local, sensor1, sensor2 */
static u8 default_limits_chip[3] = {80, 65, 80};    /* local, sensor1, sensor2 */
static const char *sensor_location[3];

static int limit_adjust;
static int fan_speed = -1;
static int verbose;

MODULE_AUTHOR("Colin Leroy <colin@colino.net>");
MODULE_DESCRIPTION("Driver for ADT746x thermostat in iBook G4 and "
		   "Powerbook G4 Alu");
MODULE_LICENSE("GPL");

module_param(limit_adjust, int, 0644);
MODULE_PARM_DESC(limit_adjust,"Adjust maximum temperatures (50 sensor1, 70 sensor2) "
		 "by N degrees.");

module_param(fan_speed, int, 0644);
MODULE_PARM_DESC(fan_speed,"Specify starting fan speed (0-255) "
		 "(default 64)");

module_param(verbose, bool, 0);
MODULE_PARM_DESC(verbose,"Verbose log operations "
		 "(default 0)");

struct thermostat {
	struct i2c_client	*clt;
	u8			temps[3];
	u8			cached_temp[3];
	u8			initial_limits[3];
	u8			limits[3];
	int			last_speed[2];
	int			last_var[2];
};

static enum {ADT7460, ADT7467} therm_type;
static int therm_bus, therm_address;
static struct of_device * of_dev;
static struct thermostat* thermostat;
static struct task_struct *thread_therm = NULL;

static void write_both_fan_speed(struct thermostat *th, int speed);
static void write_fan_speed(struct thermostat *th, int speed, int fan);

static int
write_reg(struct thermostat* th, int reg, u8 data)
{
	u8 tmp[2];
	int rc;
	
	tmp[0] = reg;
	tmp[1] = data;
	rc = i2c_master_send(th->clt, (const char *)tmp, 2);
	if (rc < 0)
		return rc;
	if (rc != 2)
		return -ENODEV;
	return 0;
}

static int
read_reg(struct thermostat* th, int reg)
{
	u8 reg_addr, data;
	int rc;

	reg_addr = (u8)reg;
	rc = i2c_master_send(th->clt, &reg_addr, 1);
	if (rc < 0)
		return rc;
	if (rc != 1)
		return -ENODEV;
	rc = i2c_master_recv(th->clt, (char *)&data, 1);
	if (rc < 0)
		return rc;
	return data;
}

static int
attach_thermostat(struct i2c_adapter *adapter)
{
	unsigned long bus_no;
	struct i2c_board_info info;
	struct i2c_client *client;

	if (strncmp(adapter->name, "uni-n", 5))
		return -ENODEV;
	bus_no = simple_strtoul(adapter->name + 6, NULL, 10);
	if (bus_no != therm_bus)
		return -ENODEV;

	memset(&info, 0, sizeof(struct i2c_board_info));
	strlcpy(info.type, "therm_adt746x", I2C_NAME_SIZE);
	info.addr = therm_address;
	client = i2c_new_device(adapter, &info);
	if (!client)
		return -ENODEV;

	/*
	 * Let i2c-core delete that device on driver removal.
	 * This is safe because i2c-core holds the core_lock mutex for us.
	 */
	list_add_tail(&client->detected, &client->driver->clients);
	return 0;
}

static int
remove_thermostat(struct i2c_client *client)
{
	struct thermostat *th = i2c_get_clientdata(client);
	int i;
	
	if (thread_therm != NULL) {
		kthread_stop(thread_therm);
	}

	printk(KERN_INFO "adt746x: Putting max temperatures back from "
			 "%d, %d, %d to %d, %d, %d\n",
		th->limits[0], th->limits[1], th->limits[2],
		th->initial_limits[0], th->initial_limits[1],
		th->initial_limits[2]);

	for (i = 0; i < 3; i++)
		write_reg(th, LIMIT_REG[i], th->initial_limits[i]);

	write_both_fan_speed(th, -1);

	thermostat = NULL;

	kfree(th);

	return 0;
}

static int read_fan_speed(struct thermostat *th, u8 addr)
{
	u8 tmp[2];
	u16 res;
	
	/* should start with low byte */
	tmp[1] = read_reg(th, addr);
	tmp[0] = read_reg(th, addr + 1);
	
	res = tmp[1] + (tmp[0] << 8);
	/* "a value of 0xffff means that the fan has stopped" */
	return (res == 0xffff ? 0 : (90000*60)/res);
}

static void write_both_fan_speed(struct thermostat *th, int speed)
{
	write_fan_speed(th, speed, 0);
	if (therm_type == ADT7460)
		write_fan_speed(th, speed, 1);
}

static void write_fan_speed(struct thermostat *th, int speed, int fan)
{
	u8 manual;
	
	if (speed > 0xff) 
		speed = 0xff;
	else if (speed < -1) 
		speed = 0;
	
	if (therm_type == ADT7467 && fan == 1)
		return;
	
	if (th->last_speed[fan] != speed) {
		if (verbose) {
			if (speed == -1)
				printk(KERN_DEBUG "adt746x: Setting speed to automatic "
					"for %s fan.\n", sensor_location[fan+1]);
			else
				printk(KERN_DEBUG "adt746x: Setting speed to %d "
					"for %s fan.\n", speed, sensor_location[fan+1]);
		}
	} else
		return;
	
	if (speed >= 0) {
		manual = read_reg(th, MANUAL_MODE[fan]);
		write_reg(th, MANUAL_MODE[fan],
			(manual|MANUAL_MASK) & (~INVERT_MASK));
		write_reg(th, FAN_SPD_SET[fan], speed);
	} else {
		/* back to automatic */
		if(therm_type == ADT7460) {
			manual = read_reg(th,
				MANUAL_MODE[fan]) & (~MANUAL_MASK);

			write_reg(th,
				MANUAL_MODE[fan], manual|REM_CONTROL[fan]);
		} else {
			manual = read_reg(th, MANUAL_MODE[fan]);
			write_reg(th, MANUAL_MODE[fan], manual&(~AUTO_MASK));
		}
	}
	
	th->last_speed[fan] = speed;			
}

static void read_sensors(struct thermostat *th)
{
	int i = 0;

	for (i = 0; i < 3; i++)
		th->temps[i]  = read_reg(th, TEMP_REG[i]);
}

#ifdef DEBUG
static void display_stats(struct thermostat *th)
{
	if (th->temps[0] != th->cached_temp[0]
	||  th->temps[1] != th->cached_temp[1]
	||  th->temps[2] != th->cached_temp[2]) {
		printk(KERN_INFO "adt746x: Temperature infos:"
				 " thermostats: %d,%d,%d;"
				 " limits: %d,%d,%d;"
				 " fan speed: %d RPM\n",
				 th->temps[0], th->temps[1], th->temps[2],
				 th->limits[0],  th->limits[1],  th->limits[2],
				 read_fan_speed(th, FAN_SPEED[0]));
	}
	th->cached_temp[0] = th->temps[0];
	th->cached_temp[1] = th->temps[1];
	th->cached_temp[2] = th->temps[2];
}
#endif

static void update_fans_speed (struct thermostat *th)
{
	int lastvar = 0; /* last variation, for iBook */
	int i = 0;

	/* we don't care about local sensor, so we start at sensor 1 */
	for (i = 1; i < 3; i++) {
		int started = 0;
		int fan_number = (therm_type == ADT7460 && i == 2);
		int var = th->temps[i] - th->limits[i];

		if (var > -1) {
			int step = (255 - fan_speed) / 7;
			int new_speed = 0;

			/* hysteresis : change fan speed only if variation is
			 * more than two degrees */
			if (abs(var - th->last_var[fan_number]) < 2)
				continue;

			started = 1;
			new_speed = fan_speed + ((var-1)*step);

			if (new_speed < fan_speed)
				new_speed = fan_speed;
			if (new_speed > 255)
				new_speed = 255;

			if (verbose)
				printk(KERN_DEBUG "adt746x: Setting fans speed to %d "
						 "(limit exceeded by %d on %s) \n",
						new_speed, var,
						sensor_location[fan_number+1]);
			write_both_fan_speed(th, new_speed);
			th->last_var[fan_number] = var;
		} else if (var < -2) {
			/* don't stop fan if sensor2 is cold and sensor1 is not
			 * so cold (lastvar >= -1) */
			if (i == 2 && lastvar < -1) {
				if (th->last_speed[fan_number] != 0)
					if (verbose)
						printk(KERN_DEBUG "adt746x: Stopping "
							"fans.\n");
				write_both_fan_speed(th, 0);
			}
		}

		lastvar = var;

		if (started)
			return; /* we don't want to re-stop the fan
				* if sensor1 is heating and sensor2 is not */
	}
}

static int monitor_task(void *arg)
{
	struct thermostat* th = arg;

	set_freezable();
	while(!kthread_should_stop()) {
		try_to_freeze();
		msleep_interruptible(2000);

#ifndef DEBUG
		if (fan_speed != -1)
			read_sensors(th);
#else
		read_sensors(th);
#endif		

		if (fan_speed != -1)
			update_fans_speed(th);

#ifdef DEBUG
		display_stats(th);
#endif

	}

	return 0;
}

static void set_limit(struct thermostat *th, int i)
{
		/* Set sensor1 limit higher to avoid powerdowns */
		th->limits[i] = default_limits_chip[i] + limit_adjust;
		write_reg(th, LIMIT_REG[i], th->limits[i]);
		
		/* set our limits to normal */
		th->limits[i] = default_limits_local[i] + limit_adjust;
}

static int probe_thermostat(struct i2c_client *client,
			    const struct i2c_device_id *id)
{
	struct thermostat* th;
	int rc;
	int i;

	if (thermostat)
		return 0;

	th = kzalloc(sizeof(struct thermostat), GFP_KERNEL);
	if (!th)
		return -ENOMEM;

	i2c_set_clientdata(client, th);
	th->clt = client;

	rc = read_reg(th, 0);
	if (rc < 0) {
		dev_err(&client->dev, "Thermostat failed to read config!\n");
		kfree(th);
		return -ENODEV;
	}

	/* force manual control to start the fan quieter */
	if (fan_speed == -1)
		fan_speed = 64;
	
	if(therm_type == ADT7460) {
		printk(KERN_INFO "adt746x: ADT7460 initializing\n");
		/* The 7460 needs to be started explicitly */
		write_reg(th, CONFIG_REG, 1);
	} else
		printk(KERN_INFO "adt746x: ADT7467 initializing\n");

	for (i = 0; i < 3; i++) {
		th->initial_limits[i] = read_reg(th, LIMIT_REG[i]);
		set_limit(th, i);
	}

	printk(KERN_INFO "adt746x: Lowering max temperatures from %d, %d, %d"
			 " to %d, %d, %d\n",
			 th->initial_limits[0], th->initial_limits[1],
			 th->initial_limits[2], th->limits[0], th->limits[1],
			 th->limits[2]);

	thermostat = th;

	/* be sure to really write fan speed the first time */
	th->last_speed[0] = -2;
	th->last_speed[1] = -2;
	th->last_var[0] = -80;
	th->last_var[1] = -80;

	if (fan_speed != -1) {
		/* manual mode, stop fans */
		write_both_fan_speed(th, 0);
	} else {
		/* automatic mode */
		write_both_fan_speed(th, -1);
	}
	
	thread_therm = kthread_run(monitor_task, th, "kfand");

	if (thread_therm == ERR_PTR(-ENOMEM)) {
		printk(KERN_INFO "adt746x: Kthread creation failed\n");
		thread_therm = NULL;
		return -ENOMEM;
	}

	return 0;
}

static const struct i2c_device_id therm_adt746x_id[] = {
	{ "therm_adt746x", 0 },
	{ }
};

static struct i2c_driver thermostat_driver = {
	.driver = {
		.name	= "therm_adt746x",
	},
	.attach_adapter	= attach_thermostat,
	.probe = probe_thermostat,
	.remove = remove_thermostat,
	.id_table = therm_adt746x_id,
};

/* 
 * Now, unfortunately, sysfs doesn't give us a nice void * we could
 * pass around to the attribute functions, so we don't really have
 * choice but implement a bunch of them...
 *
 * FIXME, it does now...
 */
#define BUILD_SHOW_FUNC_INT(name, data)				\
static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)	\
{								\
	return sprintf(buf, "%d\n", data);			\
}

#define BUILD_SHOW_FUNC_STR(name, data)				\
static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)       \
{								\
	return sprintf(buf, "%s\n", data);			\
}

#define BUILD_SHOW_FUNC_FAN(name, data)				\
static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)       \
{								\
	return sprintf(buf, "%d (%d rpm)\n", 			\
		thermostat->last_speed[data],			\
		read_fan_speed(thermostat, FAN_SPEED[data])	\
		);						\
}

#define BUILD_STORE_FUNC_DEG(name, data)			\
static ssize_t store_##name(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) \
{								\
	int val;						\
	int i;							\
	val = simple_strtol(buf, NULL, 10);			\
	printk(KERN_INFO "Adjusting limits by %d degrees\n", val);	\
	limit_adjust = val;					\
	for (i=0; i < 3; i++)					\
		set_limit(thermostat, i);			\
	return n;						\
}

#define BUILD_STORE_FUNC_INT(name, data)			\
static ssize_t store_##name(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) \
{								\
	int val;						\
	val = simple_strtol(buf, NULL, 10);			\
	if (val < 0 || val > 255)				\
		return -EINVAL;					\
	printk(KERN_INFO "Setting specified fan speed to %d\n", val);	\
	data = val;						\
	return n;						\
}

BUILD_SHOW_FUNC_INT(sensor1_temperature,	 (read_reg(thermostat, TEMP_REG[1])))
BUILD_SHOW_FUNC_INT(sensor2_temperature,	 (read_reg(thermostat, TEMP_REG[2])))
BUILD_SHOW_FUNC_INT(sensor1_limit,		 thermostat->limits[1])
BUILD_SHOW_FUNC_INT(sensor2_limit,		 thermostat->limits[2])
BUILD_SHOW_FUNC_STR(sensor1_location,		 sensor_location[1])
BUILD_SHOW_FUNC_STR(sensor2_location,		 sensor_location[2])

BUILD_SHOW_FUNC_INT(specified_fan_speed, fan_speed)
BUILD_SHOW_FUNC_FAN(sensor1_fan_speed,	 0)
BUILD_SHOW_FUNC_FAN(sensor2_fan_speed,	 1)

BUILD_STORE_FUNC_INT(specified_fan_speed,fan_speed)
BUILD_SHOW_FUNC_INT(limit_adjust,	 limit_adjust)
BUILD_STORE_FUNC_DEG(limit_adjust,	 thermostat)
		
static DEVICE_ATTR(sensor1_temperature,	S_IRUGO,
		   show_sensor1_temperature,NULL);
static DEVICE_ATTR(sensor2_temperature,	S_IRUGO,
		   show_sensor2_temperature,NULL);
static DEVICE_ATTR(sensor1_limit, S_IRUGO,
		   show_sensor1_limit,	NULL);
static DEVICE_ATTR(sensor2_limit, S_IRUGO,
		   show_sensor2_limit,	NULL);
static DEVICE_ATTR(sensor1_location, S_IRUGO,
		   show_sensor1_location, NULL);
static DEVICE_ATTR(sensor2_location, S_IRUGO,
		   show_sensor2_location, NULL);

static DEVICE_ATTR(specified_fan_speed,	S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH,
		   show_specified_fan_speed,store_specified_fan_speed);

static DEVICE_ATTR(sensor1_fan_speed,	S_IRUGO,
		   show_sensor1_fan_speed,	NULL);
static DEVICE_ATTR(sensor2_fan_speed,	S_IRUGO,
		   show_sensor2_fan_speed,	NULL);

static DEVICE_ATTR(limit_adjust,	S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH,
		   show_limit_adjust,	store_limit_adjust);


static int __init
thermostat_init(void)
{
	struct device_node* np;
	const u32 *prop;
	int i = 0, offset = 0;
	int err;

	np = of_find_node_by_name(NULL, "fan");
	if (!np)
		return -ENODEV;
	if (of_device_is_compatible(np, "adt7460"))
		therm_type = ADT7460;
	else if (of_device_is_compatible(np, "adt7467"))
		therm_type = ADT7467;
	else {
		of_node_put(np);
		return -ENODEV;
	}

	prop = of_get_property(np, "hwsensor-params-version", NULL);
	printk(KERN_INFO "adt746x: version %d (%ssupported)\n", *prop,
			 (*prop == 1)?"":"un");
	if (*prop != 1) {
		of_node_put(np);
		return -ENODEV;
	}

	prop = of_get_property(np, "reg", NULL);
	if (!prop) {
		of_node_put(np);
		return -ENODEV;
	}

	/* look for bus either by path or using "reg" */
	if (strstr(np->full_name, "/i2c-bus@") != NULL) {
		const char *tmp_bus = (strstr(np->full_name, "/i2c-bus@") + 9);
		therm_bus = tmp_bus[0]-'0';
	} else {
		therm_bus = ((*prop) >> 8) & 0x0f;
	}

	therm_address = ((*prop) & 0xff) >> 1;

	printk(KERN_INFO "adt746x: Thermostat bus: %d, address: 0x%02x, "
			 "limit_adjust: %d, fan_speed: %d\n",
			 therm_bus, therm_address, limit_adjust, fan_speed);

	if (of_get_property(np, "hwsensor-location", NULL)) {
		for (i = 0; i < 3; i++) {
			sensor_location[i] = of_get_property(np,
					"hwsensor-location", NULL) + offset;

			if (sensor_location[i] == NULL)
				sensor_location[i] = "";

			printk(KERN_INFO "sensor %d: %s\n", i, sensor_location[i]);
			offset += strlen(sensor_location[i]) + 1;
		}
	} else {
		sensor_location[0] = "?";
		sensor_location[1] = "?";
		sensor_location[2] = "?";
	}

	of_dev = of_platform_device_create(np, "temperatures", NULL);
	of_node_put(np);

	if (of_dev == NULL) {
		printk(KERN_ERR "Can't register temperatures device !\n");
		return -ENODEV;
	}

	err = device_create_file(&of_dev->dev, &dev_attr_sensor1_temperature);
	err |= device_create_file(&of_dev->dev, &dev_attr_sensor2_temperature);
	err |= device_create_file(&of_dev->dev, &dev_attr_sensor1_limit);
	err |= device_create_file(&of_dev->dev, &dev_attr_sensor2_limit);
	err |= device_create_file(&of_dev->dev, &dev_attr_sensor1_location);
	err |= device_create_file(&of_dev->dev, &dev_attr_sensor2_location);
	err |= device_create_file(&of_dev->dev, &dev_attr_limit_adjust);
	err |= device_create_file(&of_dev->dev, &dev_attr_specified_fan_speed);
	err |= device_create_file(&of_dev->dev, &dev_attr_sensor1_fan_speed);
	if(therm_type == ADT7460)
		err |= device_create_file(&of_dev->dev, &dev_attr_sensor2_fan_speed);
	if (err)
		printk(KERN_WARNING
			"Failed to create tempertaure attribute file(s).\n");

#ifndef CONFIG_I2C_POWERMAC
	request_module("i2c-powermac");
#endif

	return i2c_add_driver(&thermostat_driver);
}

static void __exit
thermostat_exit(void)
{
	if (of_dev) {
		device_remove_file(&of_dev->dev, &dev_attr_sensor1_temperature);
		device_remove_file(&of_dev->dev, &dev_attr_sensor2_temperature);
		device_remove_file(&of_dev->dev, &dev_attr_sensor1_limit);
		device_remove_file(&of_dev->dev, &dev_attr_sensor2_limit);
		device_remove_file(&of_dev->dev, &dev_attr_sensor1_location);
		device_remove_file(&of_dev->dev, &dev_attr_sensor2_location);
		device_remove_file(&of_dev->dev, &dev_attr_limit_adjust);
		device_remove_file(&of_dev->dev, &dev_attr_specified_fan_speed);
		device_remove_file(&of_dev->dev, &dev_attr_sensor1_fan_speed);

		if(therm_type == ADT7460)
			device_remove_file(&of_dev->dev,
					   &dev_attr_sensor2_fan_speed);

		of_device_unregister(of_dev);
	}
	i2c_del_driver(&thermostat_driver);
}

module_init(thermostat_init);
module_exit(thermostat_exit);