/* 
 *   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.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>

#include <asm/machdep.h>
#include <asm/io.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\n", 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\n", 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)\n", 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\n", 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\n");
        }
        /* 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(")\n");
        }

        /* 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).\n");
}

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 void do_attach(struct i2c_adapter *adapter)
{
        struct i2c_board_info info = { };
        struct device_node *np;

        /* 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 (x.running || strncmp(adapter->name, "uni-n", 5))
                return;

        of_node_get(adapter->dev.of_node);
        np = of_find_compatible_node(adapter->dev.of_node, NULL, "MAC,ds1775");
        if (np) {
                of_node_put(np);
        } else {
                strscpy(info.type, "MAC,ds1775", I2C_NAME_SIZE);
                i2c_new_scanned_device(adapter, &info, scan_ds1775, NULL);
        }

        of_node_get(adapter->dev.of_node);
        np = of_find_compatible_node(adapter->dev.of_node, NULL, "MAC,adm1030");
        if (np) {
                of_node_put(np);
        } else {
                strscpy(info.type, "MAC,adm1030", I2C_NAME_SIZE);
                i2c_new_scanned_device(adapter, &info, scan_adm1030, NULL);
        }
}

static void
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\n");
}

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]\n", 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]\n", cl->addr );
        print_temp("Temp: ", temp );
        print_temp("  Hyst: ", hyst_temp );
        print_temp("  OS: ", os_temp );
        printk("\n");

        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[] = {
        { "MAC,ds1775", ds1775 },
        { "MAC,adm1030", adm1030 },
        { }
};
MODULE_DEVICE_TABLE(i2c, therm_windtunnel_id);

static int
do_probe(struct i2c_client *cl)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(cl);
        struct i2c_adapter *adapter = cl->adapter;
        int ret = 0;

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

        switch (id->driver_data) {
        case adm1030:
                ret = attach_fan(cl);
                break;
        case ds1775:
                ret = attach_thermostat(cl);
                break;
        }

        if (!x.running && x.thermostat && x.fan) {
                x.running = 1;
                x.poll_task = kthread_run(control_loop, NULL, "g4fand");
        }

        return ret;
}

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


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

static int therm_of_probe(struct platform_device *dev)
{
        struct i2c_adapter *adap;
        int ret, i = 0;

        adap = i2c_get_adapter(0);
        if (!adap)
                return -EPROBE_DEFER;

        ret = i2c_add_driver(&g4fan_driver);
        if (ret) {
                i2c_put_adapter(adap);
                return ret;
        }

        /* We assume Macs have consecutive I2C bus numbers starting at 0 */
        while (adap) {
                do_attach(adap);
                if (x.running)
                        return 0;
                i2c_put_adapter(adap);
                adap = i2c_get_adapter(++i);
        }

        return -ENODEV;
}

static void therm_of_remove(struct platform_device *dev)
{
        i2c_del_driver( &g4fan_driver );
}

static const struct of_device_id therm_of_match[] = {{
        .name           = "fan",
        .compatible     = "adm1030"
    }, {}
};
MODULE_DEVICE_TABLE(of, therm_of_match);

static struct platform_driver therm_of_driver = {
        .driver = {
                .name = "temperature",
                .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\n", 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!\n");
                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_platform_device_destroy(&x.of_dev->dev, NULL);
}

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");