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[linux-2.6.9-moxart.git] / drivers / macintosh / therm_pm72.c

/*
 * Device driver for the thermostats & fan controller of  the
 * Apple G5 "PowerMac7,2" desktop machines.
 *
 * (c) Copyright IBM Corp. 2003-2004
 *
 * Maintained by: Benjamin Herrenschmidt
 *                <benh@kernel.crashing.org>
 * 
 *
 * The algorithm used is the PID control algorithm, used the same
 * way the published Darwin code does, using the same values that
 * are present in the Darwin 7.0 snapshot property lists.
 *
 * As far as the CPUs control loops are concerned, I use the
 * calibration & PID constants provided by the EEPROM,
 * I do _not_ embed any value from the property lists, as the ones
 * provided by Darwin 7.0 seem to always have an older version that
 * what I've seen on the actual computers.
 * It would be interesting to verify that though. Darwin has a
 * version code of 1.0.0d11 for all control loops it seems, while
 * so far, the machines EEPROMs contain a dataset versioned 1.0.0f
 *
 * Darwin doesn't provide source to all parts, some missing
 * bits like the AppleFCU driver or the actual scale of some
 * of the values returned by sensors had to be "guessed" some
 * way... or based on what Open Firmware does.
 *
 * I didn't yet figure out how to get the slots power consumption
 * out of the FCU, so that part has not been implemented yet and
 * the slots fan is set to a fixed 50% PWM, hoping this value is
 * safe enough ...
 *
 * Note: I have observed strange oscillations of the CPU control
 * loop on a dual G5 here. When idle, the CPU exhaust fan tend to
 * oscillates slowly (over several minutes) between the minimum
 * of 300RPMs and approx. 1000 RPMs. I don't know what is causing
 * this, it could be some incorrect constant or an error in the
 * way I ported the algorithm, or it could be just normal. I
 * don't have full understanding on the way Apple tweaked the PID
 * algorithm for the CPU control, it is definitely not a standard
 * implementation...
 *
 * TODO:  - Check MPU structure version/signature
 *        - Add things like /sbin/overtemp for non-critical
 *          overtemp conditions so userland can take some policy
 *          decisions, like slewing down CPUs
 *        - Deal with fan and i2c failures in a better way
 *
 * History:
 *
 *  Nov. 13, 2003 : 0.5
 *      - First release
 *
 *  Nov. 14, 2003 : 0.6
 *      - Read fan speed from FCU, low level fan routines now deal
 *        with errors & check fan status, though higher level don't
 *        do much.
 *      - Move a bunch of definitions to .h file
 *
 *  Nov. 18, 2003 : 0.7
 *      - Fix build on ppc64 kernel
 *      - Move back statics definitions to .c file
 *      - Avoid calling schedule_timeout with a negative number
 *
 *  Dec. 18, 2003 : 0.8
 *      - Fix typo when reading back fan speed on 2 CPU machines
 *
 *  Mar. 11, 2004 : 0.9
 *      - Rework code accessing the ADC chips, make it more robust and
 *        closer to the chip spec. Also make sure it is configured properly,
 *        I've seen yet unexplained cases where on startup, I would have stale
 *        values in the configuration register
 *      - Switch back to use of target fan speed for PID, thus lowering
 *        pressure on i2c
 */

#include <linux/config.h>
#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/smp_lock.h>
#include <linux/wait.h>
#include <linux/reboot.h>
#include <linux/kmod.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/sections.h>
#include <asm/of_device.h>

#include "therm_pm72.h"

#define VERSION "0.9"

#undef DEBUG

#ifdef DEBUG
#define DBG(args...)    printk(args)
#else
#define DBG(args...)    do { } while(0)
#endif


/*
 * Driver statics
 */

static struct of_device *               of_dev;
static struct i2c_adapter *             u3_0;
static struct i2c_adapter *             u3_1;
static struct i2c_client *              fcu;
static struct cpu_pid_state             cpu_state[2];
static struct backside_pid_state        backside_state;
static struct drives_pid_state          drives_state;
static int                              state;
static int                              cpu_count;
static pid_t                            ctrl_task;
static struct completion                ctrl_complete;
static int                              critical_state;
static DECLARE_MUTEX(driver_lock);

/*
 * i2c_driver structure to attach to the host i2c controller
 */

static int therm_pm72_attach(struct i2c_adapter *adapter);
static int therm_pm72_detach(struct i2c_adapter *adapter);

static struct i2c_driver therm_pm72_driver =
{
        .name           = "therm_pm72",
        .id             = 0xDEADBEEF,
        .flags          = I2C_DF_NOTIFY,
        .attach_adapter = therm_pm72_attach,
        .detach_adapter = therm_pm72_detach,
};

/*
 * Utility function to create an i2c_client structure and
 * attach it to one of u3 adapters
 */
static struct i2c_client *attach_i2c_chip(int id, const char *name)
{
        struct i2c_client *clt;
        struct i2c_adapter *adap;

        if (id & 0x100)
                adap = u3_1;
        else
                adap = u3_0;
        if (adap == NULL)
                return NULL;

        clt = kmalloc(sizeof(struct i2c_client), GFP_KERNEL);
        if (clt == NULL)
                return NULL;
        memset(clt, 0, sizeof(struct i2c_client));

        clt->addr = (id >> 1) & 0x7f;
        clt->adapter = adap;
        clt->driver = &therm_pm72_driver;
        clt->id = 0xDEADBEEF;
        strncpy(clt->name, name, I2C_NAME_SIZE-1);

        if (i2c_attach_client(clt)) {
                printk(KERN_ERR "therm_pm72: Failed to attach to i2c ID 0x%x\n", id);
                kfree(clt);
                return NULL;
        }
        return clt;
}

/*
 * Utility function to get rid of the i2c_client structure
 * (will also detach from the adapter hopepfully)
 */
static void detach_i2c_chip(struct i2c_client *clt)
{
        i2c_detach_client(clt);
        kfree(clt);
}

/*
 * Here are the i2c chip access wrappers
 */

static void initialize_adc(struct cpu_pid_state *state)
{
        int rc;
        u8 buf[2];

        /* Read ADC the configuration register and cache it. We
         * also make sure Config2 contains proper values, I've seen
         * cases where we got stale grabage in there, thus preventing
         * proper reading of conv. values
         */

        /* Clear Config2 */
        buf[0] = 5;
        buf[1] = 0;
        i2c_master_send(state->monitor, buf, 2);

        /* Read & cache Config1 */
        buf[0] = 1;
        rc = i2c_master_send(state->monitor, buf, 1);
        if (rc > 0) {
                rc = i2c_master_recv(state->monitor, buf, 1);
                if (rc > 0) {
                        state->adc_config = buf[0];
                        DBG("ADC config reg: %02x\n", state->adc_config);
                        /* Disable shutdown mode */
                        state->adc_config &= 0xfe;
                        buf[0] = 1;
                        buf[1] = state->adc_config;
                        rc = i2c_master_send(state->monitor, buf, 2);
                }
        }
        if (rc <= 0)
                printk(KERN_ERR "therm_pm72: Error reading ADC config"
                       " register !\n");
}

static int read_smon_adc(struct cpu_pid_state *state, int chan)
{
        int rc, data, tries = 0;
        u8 buf[2];

        for (;;) {
                /* Set channel */
                buf[0] = 1;
                buf[1] = (state->adc_config & 0x1f) | (chan << 5);
                rc = i2c_master_send(state->monitor, buf, 2);
                if (rc <= 0)
                        goto error;
                /* Wait for convertion */
                msleep(1);
                /* Switch to data register */
                buf[0] = 4;
                rc = i2c_master_send(state->monitor, buf, 1);
                if (rc <= 0)
                        goto error;
                /* Read result */
                rc = i2c_master_recv(state->monitor, buf, 2);
                if (rc < 0)
                        goto error;
                data = ((u16)buf[0]) << 8 | (u16)buf[1];
                return data >> 6;
        error:
                DBG("Error reading ADC, retrying...\n");
                if (++tries > 10) {
                        printk(KERN_ERR "therm_pm72: Error reading ADC !\n");
                        return -1;
                }
                msleep(10);
        }
}

static int fan_read_reg(int reg, unsigned char *buf, int nb)
{
        int tries, nr, nw;

        buf[0] = reg;
        tries = 0;
        for (;;) {
                nw = i2c_master_send(fcu, buf, 1);
                if (nw > 0 || (nw < 0 && nw != -EIO) || tries >= 100)
                        break;
                msleep(10);
                ++tries;
        }
        if (nw <= 0) {
                printk(KERN_ERR "Failure writing address to FCU: %d", nw);
                return -EIO;
        }
        tries = 0;
        for (;;) {
                nr = i2c_master_recv(fcu, buf, nb);
                if (nr > 0 || (nr < 0 && nr != ENODEV) || tries >= 100)
                        break;
                msleep(10);
                ++tries;
        }
        if (nr <= 0)
                printk(KERN_ERR "Failure reading data from FCU: %d", nw);
        return nr;
}

static int fan_write_reg(int reg, const unsigned char *ptr, int nb)
{
        int tries, nw;
        unsigned char buf[16];

        buf[0] = reg;
        memcpy(buf+1, ptr, nb);
        ++nb;
        tries = 0;
        for (;;) {
                nw = i2c_master_send(fcu, buf, nb);
                if (nw > 0 || (nw < 0 && nw != EIO) || tries >= 100)
                        break;
                msleep(10);
                ++tries;
        }
        if (nw < 0)
                printk(KERN_ERR "Failure writing to FCU: %d", nw);
        return nw;
}

static int start_fcu(void)
{
        unsigned char buf = 0xff;
        int rc;

        rc = fan_write_reg(0xe, &buf, 1);
        if (rc < 0)
                return -EIO;
        rc = fan_write_reg(0x2e, &buf, 1);
        if (rc < 0)
                return -EIO;
        return 0;
}

static int set_rpm_fan(int fan, int rpm)
{
        unsigned char buf[2];
        int rc;

        if (rpm < 300)
                rpm = 300;
        else if (rpm > 8191)
                rpm = 8191;
        buf[0] = rpm >> 5;
        buf[1] = rpm << 3;
        rc = fan_write_reg(0x10 + (fan * 2), buf, 2);
        if (rc < 0)
                return -EIO;
        return 0;
}

static int get_rpm_fan(int fan, int programmed)
{
        unsigned char failure;
        unsigned char active;
        unsigned char buf[2];
        int rc, reg_base;

        rc = fan_read_reg(0xb, &failure, 1);
        if (rc != 1)
                return -EIO;
        if ((failure & (1 << fan)) != 0)
                return -EFAULT;
        rc = fan_read_reg(0xd, &active, 1);
        if (rc != 1)
                return -EIO;
        if ((active & (1 << fan)) == 0)
                return -ENXIO;

        /* Programmed value or real current speed */
        reg_base = programmed ? 0x10 : 0x11;
        rc = fan_read_reg(reg_base + (fan * 2), buf, 2);
        if (rc != 2)
                return -EIO;

        return (buf[0] << 5) | buf[1] >> 3;
}

static int set_pwm_fan(int fan, int pwm)
{
        unsigned char buf[2];
        int rc;

        if (pwm < 10)
                pwm = 10;
        else if (pwm > 100)
                pwm = 100;
        pwm = (pwm * 2559) / 1000;
        buf[0] = pwm;
        rc = fan_write_reg(0x30 + (fan * 2), buf, 1);
        if (rc < 0)
                return rc;
        return 0;
}

static int get_pwm_fan(int fan)
{
        unsigned char failure;
        unsigned char active;
        unsigned char buf[2];
        int rc;

        rc = fan_read_reg(0x2b, &failure, 1);
        if (rc != 1)
                return -EIO;
        if ((failure & (1 << fan)) != 0)
                return -EFAULT;
        rc = fan_read_reg(0x2d, &active, 1);
        if (rc != 1)
                return -EIO;
        if ((active & (1 << fan)) == 0)
                return -ENXIO;

        /* Programmed value or real current speed */
        rc = fan_read_reg(0x30 + (fan * 2), buf, 1);
        if (rc != 1)
                return -EIO;

        return (buf[0] * 1000) / 2559;
}

/*
 * Utility routine to read the CPU calibration EEPROM data
 * from the device-tree
 */
static int read_eeprom(int cpu, struct mpu_data *out)
{
        struct device_node *np;
        char nodename[64];
        u8 *data;
        int len;

        /* prom.c routine for finding a node by path is a bit brain dead
         * and requires exact @xxx unit numbers. This is a bit ugly but
         * will work for these machines
         */
        sprintf(nodename, "/u3@0,f8000000/i2c@f8001000/cpuid@a%d", cpu ? 2 : 0);
        np = of_find_node_by_path(nodename);
        if (np == NULL) {
                printk(KERN_ERR "therm_pm72: Failed to retreive cpuid node from device-tree\n");
                return -ENODEV;
        }
        data = (u8 *)get_property(np, "cpuid", &len);
        if (data == NULL) {
                printk(KERN_ERR "therm_pm72: Failed to retreive cpuid property from device-tree\n");
                of_node_put(np);
                return -ENODEV;
        }
        memcpy(out, data, sizeof(struct mpu_data));
        of_node_put(np);
        
        return 0;
}

/* 
 * 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...
 *
 * That sucks a bit, we take the lock because FIX32TOPRINT evaluates
 * the input twice... I accept patches :)
 */
#define BUILD_SHOW_FUNC_FIX(name, data)                         \
static ssize_t show_##name(struct device *dev, char *buf)       \
{                                                               \
        ssize_t r;                                              \
        down(&driver_lock);                                     \
        r = sprintf(buf, "%d.%03d", FIX32TOPRINT(data));        \
        up(&driver_lock);                                       \
        return r;                                               \
}
#define BUILD_SHOW_FUNC_INT(name, data)                         \
static ssize_t show_##name(struct device *dev, char *buf)       \
{                                                               \
        return sprintf(buf, "%d", data);                        \
}

BUILD_SHOW_FUNC_FIX(cpu0_temperature, cpu_state[0].last_temp)
BUILD_SHOW_FUNC_FIX(cpu0_voltage, cpu_state[0].voltage)
BUILD_SHOW_FUNC_FIX(cpu0_current, cpu_state[0].current_a)
BUILD_SHOW_FUNC_INT(cpu0_exhaust_fan_rpm, cpu_state[0].rpm)
BUILD_SHOW_FUNC_INT(cpu0_intake_fan_rpm, cpu_state[0].intake_rpm)

BUILD_SHOW_FUNC_FIX(cpu1_temperature, cpu_state[1].last_temp)
BUILD_SHOW_FUNC_FIX(cpu1_voltage, cpu_state[1].voltage)
BUILD_SHOW_FUNC_FIX(cpu1_current, cpu_state[1].current_a)
BUILD_SHOW_FUNC_INT(cpu1_exhaust_fan_rpm, cpu_state[1].rpm)
BUILD_SHOW_FUNC_INT(cpu1_intake_fan_rpm, cpu_state[1].intake_rpm)

BUILD_SHOW_FUNC_FIX(backside_temperature, backside_state.last_temp)
BUILD_SHOW_FUNC_INT(backside_fan_pwm, backside_state.pwm)

BUILD_SHOW_FUNC_FIX(drives_temperature, drives_state.last_temp)
BUILD_SHOW_FUNC_INT(drives_fan_rpm, drives_state.rpm)

static DEVICE_ATTR(cpu0_temperature,S_IRUGO,show_cpu0_temperature,NULL);
static DEVICE_ATTR(cpu0_voltage,S_IRUGO,show_cpu0_voltage,NULL);
static DEVICE_ATTR(cpu0_current,S_IRUGO,show_cpu0_current,NULL);
static DEVICE_ATTR(cpu0_exhaust_fan_rpm,S_IRUGO,show_cpu0_exhaust_fan_rpm,NULL);
static DEVICE_ATTR(cpu0_intake_fan_rpm,S_IRUGO,show_cpu0_intake_fan_rpm,NULL);

static DEVICE_ATTR(cpu1_temperature,S_IRUGO,show_cpu1_temperature,NULL);
static DEVICE_ATTR(cpu1_voltage,S_IRUGO,show_cpu1_voltage,NULL);
static DEVICE_ATTR(cpu1_current,S_IRUGO,show_cpu1_current,NULL);
static DEVICE_ATTR(cpu1_exhaust_fan_rpm,S_IRUGO,show_cpu1_exhaust_fan_rpm,NULL);
static DEVICE_ATTR(cpu1_intake_fan_rpm,S_IRUGO,show_cpu1_intake_fan_rpm,NULL);

static DEVICE_ATTR(backside_temperature,S_IRUGO,show_backside_temperature,NULL);
static DEVICE_ATTR(backside_fan_pwm,S_IRUGO,show_backside_fan_pwm,NULL);

static DEVICE_ATTR(drives_temperature,S_IRUGO,show_drives_temperature,NULL);
static DEVICE_ATTR(drives_fan_rpm,S_IRUGO,show_drives_fan_rpm,NULL);

/*
 * CPUs fans control loop
 */
static void do_monitor_cpu(struct cpu_pid_state *state)
{
        s32 temp, voltage, current_a, power, power_target;
        s32 integral, derivative, proportional, adj_in_target, sval;
        s64 integ_p, deriv_p, prop_p, sum; 
        int i, intake, rc;

        DBG("cpu %d:\n", state->index);

        /* Read current fan status */
        if (state->index == 0)
                rc = get_rpm_fan(CPUA_EXHAUST_FAN_RPM_ID, !RPM_PID_USE_ACTUAL_SPEED);
        else
                rc = get_rpm_fan(CPUB_EXHAUST_FAN_RPM_ID, !RPM_PID_USE_ACTUAL_SPEED);
        if (rc < 0) {
                printk(KERN_WARNING "Error %d reading CPU %d exhaust fan !\n",
                       rc, state->index);
                /* XXX What do we do now ? */
        } else
                state->rpm = rc;
        DBG("  current rpm: %d\n", state->rpm);

        /* Get some sensor readings and scale it */
        temp = read_smon_adc(state, 1);
        if (temp == -1) {
                state->overtemp++;
                return;
        }
        voltage = read_smon_adc(state, 3);
        current_a = read_smon_adc(state, 4);

        /* Fixup temperature according to diode calibration
         */
        DBG("  temp raw: %04x, m_diode: %04x, b_diode: %04x\n",
            temp, state->mpu.mdiode, state->mpu.bdiode);
        temp = ((s32)temp * (s32)state->mpu.mdiode + ((s32)state->mpu.bdiode << 12)) >> 2;
        state->last_temp = temp;
        DBG("  temp: %d.%03d\n", FIX32TOPRINT(temp));

        /* Check tmax, increment overtemp if we are there. At tmax+8, we go
         * full blown immediately and try to trigger a shutdown
         */
        if (temp >= ((state->mpu.tmax + 8) << 16)) {
                printk(KERN_WARNING "Warning ! CPU %d temperature way above maximum"
                       " (%d) !\n",
                       state->index, temp >> 16);
                state->overtemp = CPU_MAX_OVERTEMP;
        } else if (temp > (state->mpu.tmax << 16))
                state->overtemp++;
        else
                state->overtemp = 0;
        if (state->overtemp >= CPU_MAX_OVERTEMP)
                critical_state = 1;
        if (state->overtemp > 0) {
                state->rpm = state->mpu.rmaxn_exhaust_fan;
                state->intake_rpm = intake = state->mpu.rmaxn_intake_fan;
                goto do_set_fans;
        }
        
        /* Scale other sensor values according to fixed scales
         * obtained in Darwin and calculate power from I and V
         */
        state->voltage = voltage *= ADC_CPU_VOLTAGE_SCALE;
        state->current_a = current_a *= ADC_CPU_CURRENT_SCALE;
        power = (((u64)current_a) * ((u64)voltage)) >> 16;

        /* Calculate power target value (could be done once for all)
         * and convert to a 16.16 fp number
         */
        power_target = ((u32)(state->mpu.pmaxh - state->mpu.padjmax)) << 16;

        DBG("  current: %d.%03d, voltage: %d.%03d\n",
            FIX32TOPRINT(current_a), FIX32TOPRINT(voltage));
        DBG("  power: %d.%03d W, target: %d.%03d, error: %d.%03d\n", FIX32TOPRINT(power),
            FIX32TOPRINT(power_target), FIX32TOPRINT(power_target - power));

        /* Store temperature and power in history array */
        state->cur_temp = (state->cur_temp + 1) % CPU_TEMP_HISTORY_SIZE;
        state->temp_history[state->cur_temp] = temp;
        state->cur_power = (state->cur_power + 1) % state->count_power;
        state->power_history[state->cur_power] = power;
        state->error_history[state->cur_power] = power_target - power;
        
        /* If first loop, fill the history table */
        if (state->first) {
                for (i = 0; i < (state->count_power - 1); i++) {
                        state->cur_power = (state->cur_power + 1) % state->count_power;
                        state->power_history[state->cur_power] = power;
                        state->error_history[state->cur_power] = power_target - power;
                }
                for (i = 0; i < (CPU_TEMP_HISTORY_SIZE - 1); i++) {
                        state->cur_temp = (state->cur_temp + 1) % CPU_TEMP_HISTORY_SIZE;
                        state->temp_history[state->cur_temp] = temp;                    
                }
                state->first = 0;
        }

        /* Calculate the integral term normally based on the "power" values */
        sum = 0;
        integral = 0;
        for (i = 0; i < state->count_power; i++)
                integral += state->error_history[i];
        integral *= CPU_PID_INTERVAL;
        DBG("  integral: %08x\n", integral);

        /* Calculate the adjusted input (sense value).
         *   G_r is 12.20
         *   integ is 16.16
         *   so the result is 28.36
         *
         * input target is mpu.ttarget, input max is mpu.tmax
         */
        integ_p = ((s64)state->mpu.pid_gr) * (s64)integral;
        DBG("   integ_p: %d\n", (int)(deriv_p >> 36));
        sval = (state->mpu.tmax << 16) - ((integ_p >> 20) & 0xffffffff);
        adj_in_target = (state->mpu.ttarget << 16);
        if (adj_in_target > sval)
                adj_in_target = sval;
        DBG("   adj_in_target: %d.%03d, ttarget: %d\n", FIX32TOPRINT(adj_in_target),
            state->mpu.ttarget);

        /* Calculate the derivative term */
        derivative = state->temp_history[state->cur_temp] -
                state->temp_history[(state->cur_temp + CPU_TEMP_HISTORY_SIZE - 1)
                                    % CPU_TEMP_HISTORY_SIZE];
        derivative /= CPU_PID_INTERVAL;
        deriv_p = ((s64)state->mpu.pid_gd) * (s64)derivative;
        DBG("   deriv_p: %d\n", (int)(deriv_p >> 36));
        sum += deriv_p;

        /* Calculate the proportional term */
        proportional = temp - adj_in_target;
        prop_p = ((s64)state->mpu.pid_gp) * (s64)proportional;
        DBG("   prop_p: %d\n", (int)(prop_p >> 36));
        sum += prop_p;

        /* Scale sum */
        sum >>= 36;

        DBG("   sum: %d\n", (int)sum);
        state->rpm += (s32)sum;

        if (state->rpm < state->mpu.rminn_exhaust_fan)
                state->rpm = state->mpu.rminn_exhaust_fan;
        if (state->rpm > state->mpu.rmaxn_exhaust_fan)
                state->rpm = state->mpu.rmaxn_exhaust_fan;

        intake = (state->rpm * CPU_INTAKE_SCALE) >> 16;
        if (intake < state->mpu.rminn_intake_fan)
                intake = state->mpu.rminn_intake_fan;
        if (intake > state->mpu.rmaxn_intake_fan)
                intake = state->mpu.rmaxn_intake_fan;
        state->intake_rpm = intake;

 do_set_fans:
        DBG("** CPU %d RPM: %d Ex, %d In, overtemp: %d\n",
            state->index, (int)state->rpm, intake, state->overtemp);

        /* We should check for errors, shouldn't we ? But then, what
         * do we do once the error occurs ? For FCU notified fan
         * failures (-EFAULT) we probably want to notify userland
         * some way...
         */
        if (state->index == 0) {
                set_rpm_fan(CPUA_INTAKE_FAN_RPM_ID, intake);
                set_rpm_fan(CPUA_EXHAUST_FAN_RPM_ID, state->rpm);
        } else {
                set_rpm_fan(CPUB_INTAKE_FAN_RPM_ID, intake);
                set_rpm_fan(CPUB_EXHAUST_FAN_RPM_ID, state->rpm);
        }
}

/*
 * Initialize the state structure for one CPU control loop
 */
static int init_cpu_state(struct cpu_pid_state *state, int index)
{
        state->index = index;
        state->first = 1;
        state->rpm = 1000;
        state->overtemp = 0;
        state->adc_config = 0x00;

        if (index == 0)
                state->monitor = attach_i2c_chip(SUPPLY_MONITOR_ID, "CPU0_monitor");
        else if (index == 1)
                state->monitor = attach_i2c_chip(SUPPLY_MONITORB_ID, "CPU1_monitor");
        if (state->monitor == NULL)
                goto fail;

        if (read_eeprom(index, &state->mpu))
                goto fail;

        state->count_power = state->mpu.tguardband;
        if (state->count_power > CPU_POWER_HISTORY_SIZE) {
                printk(KERN_WARNING "Warning ! too many power history slots\n");
                state->count_power = CPU_POWER_HISTORY_SIZE;
        }
        DBG("CPU %d Using %d power history entries\n", index, state->count_power);

        if (index == 0) {
                device_create_file(&of_dev->dev, &dev_attr_cpu0_temperature);
                device_create_file(&of_dev->dev, &dev_attr_cpu0_voltage);
                device_create_file(&of_dev->dev, &dev_attr_cpu0_current);
                device_create_file(&of_dev->dev, &dev_attr_cpu0_exhaust_fan_rpm);
                device_create_file(&of_dev->dev, &dev_attr_cpu0_intake_fan_rpm);
        } else {
                device_create_file(&of_dev->dev, &dev_attr_cpu1_temperature);
                device_create_file(&of_dev->dev, &dev_attr_cpu1_voltage);
                device_create_file(&of_dev->dev, &dev_attr_cpu1_current);
                device_create_file(&of_dev->dev, &dev_attr_cpu1_exhaust_fan_rpm);
                device_create_file(&of_dev->dev, &dev_attr_cpu1_intake_fan_rpm);
        }

        return 0;
 fail:
        if (state->monitor)
                detach_i2c_chip(state->monitor);
        state->monitor = NULL;
        
        return -ENODEV;
}

/*
 * Dispose of the state data for one CPU control loop
 */
static void dispose_cpu_state(struct cpu_pid_state *state)
{
        if (state->monitor == NULL)
                return;

        if (state->index == 0) {
                device_remove_file(&of_dev->dev, &dev_attr_cpu0_temperature);
                device_remove_file(&of_dev->dev, &dev_attr_cpu0_voltage);
                device_remove_file(&of_dev->dev, &dev_attr_cpu0_current);
                device_remove_file(&of_dev->dev, &dev_attr_cpu0_exhaust_fan_rpm);
                device_remove_file(&of_dev->dev, &dev_attr_cpu0_intake_fan_rpm);
        } else {
                device_remove_file(&of_dev->dev, &dev_attr_cpu1_temperature);
                device_remove_file(&of_dev->dev, &dev_attr_cpu1_voltage);
                device_remove_file(&of_dev->dev, &dev_attr_cpu1_current);
                device_remove_file(&of_dev->dev, &dev_attr_cpu1_exhaust_fan_rpm);
                device_remove_file(&of_dev->dev, &dev_attr_cpu1_intake_fan_rpm);
        }

        detach_i2c_chip(state->monitor);
        state->monitor = NULL;
}

/*
 * Motherboard backside & U3 heatsink fan control loop
 */
static void do_monitor_backside(struct backside_pid_state *state)
{
        s32 temp, integral, derivative;
        s64 integ_p, deriv_p, prop_p, sum; 
        int i, rc;

        if (--state->ticks != 0)
                return;
        state->ticks = BACKSIDE_PID_INTERVAL;

        DBG("backside:\n");

        /* Check fan status */
        rc = get_pwm_fan(BACKSIDE_FAN_PWM_ID);
        if (rc < 0) {
                printk(KERN_WARNING "Error %d reading backside fan !\n", rc);
                /* XXX What do we do now ? */
        } else
                state->pwm = rc;
        DBG("  current pwm: %d\n", state->pwm);

        /* Get some sensor readings */
        temp = i2c_smbus_read_byte_data(state->monitor, MAX6690_EXT_TEMP) << 16;
        state->last_temp = temp;
        DBG("  temp: %d.%03d, target: %d.%03d\n", FIX32TOPRINT(temp),
            FIX32TOPRINT(BACKSIDE_PID_INPUT_TARGET));

        /* Store temperature and error in history array */
        state->cur_sample = (state->cur_sample + 1) % BACKSIDE_PID_HISTORY_SIZE;
        state->sample_history[state->cur_sample] = temp;
        state->error_history[state->cur_sample] = temp - BACKSIDE_PID_INPUT_TARGET;
        
        /* If first loop, fill the history table */
        if (state->first) {
                for (i = 0; i < (BACKSIDE_PID_HISTORY_SIZE - 1); i++) {
                        state->cur_sample = (state->cur_sample + 1) %
                                BACKSIDE_PID_HISTORY_SIZE;
                        state->sample_history[state->cur_sample] = temp;
                        state->error_history[state->cur_sample] =
                                temp - BACKSIDE_PID_INPUT_TARGET;
                }
                state->first = 0;
        }

        /* Calculate the integral term */
        sum = 0;
        integral = 0;
        for (i = 0; i < BACKSIDE_PID_HISTORY_SIZE; i++)
                integral += state->error_history[i];
        integral *= BACKSIDE_PID_INTERVAL;
        DBG("  integral: %08x\n", integral);
        integ_p = ((s64)BACKSIDE_PID_G_r) * (s64)integral;
        DBG("   integ_p: %d\n", (int)(integ_p >> 36));
        sum += integ_p;

        /* Calculate the derivative term */
        derivative = state->error_history[state->cur_sample] -
                state->error_history[(state->cur_sample + BACKSIDE_PID_HISTORY_SIZE - 1)
                                    % BACKSIDE_PID_HISTORY_SIZE];
        derivative /= BACKSIDE_PID_INTERVAL;
        deriv_p = ((s64)BACKSIDE_PID_G_d) * (s64)derivative;
        DBG("   deriv_p: %d\n", (int)(deriv_p >> 36));
        sum += deriv_p;

        /* Calculate the proportional term */
        prop_p = ((s64)BACKSIDE_PID_G_p) * (s64)(state->error_history[state->cur_sample]);
        DBG("   prop_p: %d\n", (int)(prop_p >> 36));
        sum += prop_p;

        /* Scale sum */
        sum >>= 36;

        DBG("   sum: %d\n", (int)sum);
        state->pwm += (s32)sum;
        if (state->pwm < BACKSIDE_PID_OUTPUT_MIN)
                state->pwm = BACKSIDE_PID_OUTPUT_MIN;
        if (state->pwm > BACKSIDE_PID_OUTPUT_MAX)
                state->pwm = BACKSIDE_PID_OUTPUT_MAX;

        DBG("** BACKSIDE PWM: %d\n", (int)state->pwm);
        set_pwm_fan(BACKSIDE_FAN_PWM_ID, state->pwm);
}

/*
 * Initialize the state structure for the backside fan control loop
 */
static int init_backside_state(struct backside_pid_state *state)
{
        state->ticks = 1;
        state->first = 1;
        state->pwm = 50;

        state->monitor = attach_i2c_chip(BACKSIDE_MAX_ID, "backside_temp");
        if (state->monitor == NULL)
                return -ENODEV;

        device_create_file(&of_dev->dev, &dev_attr_backside_temperature);
        device_create_file(&of_dev->dev, &dev_attr_backside_fan_pwm);

        return 0;
}

/*
 * Dispose of the state data for the backside control loop
 */
static void dispose_backside_state(struct backside_pid_state *state)
{
        if (state->monitor == NULL)
                return;

        device_remove_file(&of_dev->dev, &dev_attr_backside_temperature);
        device_remove_file(&of_dev->dev, &dev_attr_backside_fan_pwm);

        detach_i2c_chip(state->monitor);
        state->monitor = NULL;
}
 
/*
 * Drives bay fan control loop
 */
static void do_monitor_drives(struct drives_pid_state *state)
{
        s32 temp, integral, derivative;
        s64 integ_p, deriv_p, prop_p, sum; 
        int i, rc;

        if (--state->ticks != 0)
                return;
        state->ticks = DRIVES_PID_INTERVAL;

        DBG("drives:\n");

        /* Check fan status */
        rc = get_rpm_fan(DRIVES_FAN_RPM_ID, !RPM_PID_USE_ACTUAL_SPEED);
        if (rc < 0) {
                printk(KERN_WARNING "Error %d reading drives fan !\n", rc);
                /* XXX What do we do now ? */
        } else
                state->rpm = rc;
        DBG("  current rpm: %d\n", state->rpm);

        /* Get some sensor readings */
        temp = le16_to_cpu(i2c_smbus_read_word_data(state->monitor, DS1775_TEMP)) << 8;
        state->last_temp = temp;
        DBG("  temp: %d.%03d, target: %d.%03d\n", FIX32TOPRINT(temp),
            FIX32TOPRINT(DRIVES_PID_INPUT_TARGET));

        /* Store temperature and error in history array */
        state->cur_sample = (state->cur_sample + 1) % DRIVES_PID_HISTORY_SIZE;
        state->sample_history[state->cur_sample] = temp;
        state->error_history[state->cur_sample] = temp - DRIVES_PID_INPUT_TARGET;
        
        /* If first loop, fill the history table */
        if (state->first) {
                for (i = 0; i < (DRIVES_PID_HISTORY_SIZE - 1); i++) {
                        state->cur_sample = (state->cur_sample + 1) %
                                DRIVES_PID_HISTORY_SIZE;
                        state->sample_history[state->cur_sample] = temp;
                        state->error_history[state->cur_sample] =
                                temp - DRIVES_PID_INPUT_TARGET;
                }
                state->first = 0;
        }

        /* Calculate the integral term */
        sum = 0;
        integral = 0;
        for (i = 0; i < DRIVES_PID_HISTORY_SIZE; i++)
                integral += state->error_history[i];
        integral *= DRIVES_PID_INTERVAL;
        DBG("  integral: %08x\n", integral);
        integ_p = ((s64)DRIVES_PID_G_r) * (s64)integral;
        DBG("   integ_p: %d\n", (int)(integ_p >> 36));
        sum += integ_p;

        /* Calculate the derivative term */
        derivative = state->error_history[state->cur_sample] -
                state->error_history[(state->cur_sample + DRIVES_PID_HISTORY_SIZE - 1)
                                    % DRIVES_PID_HISTORY_SIZE];
        derivative /= DRIVES_PID_INTERVAL;
        deriv_p = ((s64)DRIVES_PID_G_d) * (s64)derivative;
        DBG("   deriv_p: %d\n", (int)(deriv_p >> 36));
        sum += deriv_p;

        /* Calculate the proportional term */
        prop_p = ((s64)DRIVES_PID_G_p) * (s64)(state->error_history[state->cur_sample]);
        DBG("   prop_p: %d\n", (int)(prop_p >> 36));
        sum += prop_p;

        /* Scale sum */
        sum >>= 36;

        DBG("   sum: %d\n", (int)sum);
        state->rpm += (s32)sum;
        if (state->rpm < DRIVES_PID_OUTPUT_MIN)
                state->rpm = DRIVES_PID_OUTPUT_MIN;
        if (state->rpm > DRIVES_PID_OUTPUT_MAX)
                state->rpm = DRIVES_PID_OUTPUT_MAX;

        DBG("** DRIVES RPM: %d\n", (int)state->rpm);
        set_rpm_fan(DRIVES_FAN_RPM_ID, state->rpm);
}

/*
 * Initialize the state structure for the drives bay fan control loop
 */
static int init_drives_state(struct drives_pid_state *state)
{
        state->ticks = 1;
        state->first = 1;
        state->rpm = 1000;

        state->monitor = attach_i2c_chip(DRIVES_DALLAS_ID, "drives_temp");
        if (state->monitor == NULL)
                return -ENODEV;

        device_create_file(&of_dev->dev, &dev_attr_drives_temperature);
        device_create_file(&of_dev->dev, &dev_attr_drives_fan_rpm);

        return 0;
}

/*
 * Dispose of the state data for the drives control loop
 */
static void dispose_drives_state(struct drives_pid_state *state)
{
        if (state->monitor == NULL)
                return;

        device_remove_file(&of_dev->dev, &dev_attr_drives_temperature);
        device_remove_file(&of_dev->dev, &dev_attr_drives_fan_rpm);

        detach_i2c_chip(state->monitor);
        state->monitor = NULL;
}

static int call_critical_overtemp(void)
{
        char *argv[] = { critical_overtemp_path, NULL };
        static char *envp[] = { "HOME=/",
                                "TERM=linux",
                                "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
                                NULL };

        return call_usermodehelper(critical_overtemp_path, argv, envp, 0);
}


/*
 * Here's the kernel thread that calls the various control loops
 */
static int main_control_loop(void *x)
{
        daemonize("kfand");

        DBG("main_control_loop started\n");

        down(&driver_lock);

        if (start_fcu() < 0) {
                printk(KERN_ERR "kfand: failed to start FCU\n");
                up(&driver_lock);
                goto out;
        }

        /* Set the PCI fan once for now */
        set_pwm_fan(SLOTS_FAN_PWM_ID, SLOTS_FAN_DEFAULT_PWM);

        /* Initialize ADCs */
        initialize_adc(&cpu_state[0]);
        if (cpu_state[1].monitor != NULL)
                initialize_adc(&cpu_state[1]);

        up(&driver_lock);

        while (state == state_attached) {
                unsigned long elapsed, start;

                start = jiffies;

                down(&driver_lock);
                do_monitor_cpu(&cpu_state[0]);
                if (cpu_state[1].monitor != NULL)
                        do_monitor_cpu(&cpu_state[1]);
                do_monitor_backside(&backside_state);
                do_monitor_drives(&drives_state);
                up(&driver_lock);

                if (critical_state == 1) {
                        printk(KERN_WARNING "Temperature control detected a critical condition\n");
                        printk(KERN_WARNING "Attempting to shut down...\n");
                        if (call_critical_overtemp()) {
                                printk(KERN_WARNING "Can't call %s, power off now!\n",
                                       critical_overtemp_path);
                                machine_power_off();
                        }
                }
                if (critical_state > 0)
                        critical_state++;
                if (critical_state > MAX_CRITICAL_STATE) {
                        printk(KERN_WARNING "Shutdown timed out, power off now !\n");
                        machine_power_off();
                }

                // FIXME: Deal with signals
                set_current_state(TASK_INTERRUPTIBLE);
                elapsed = jiffies - start;
                if (elapsed < HZ)
                        schedule_timeout(HZ - elapsed);
        }

 out:
        DBG("main_control_loop ended\n");

        ctrl_task = 0;
        complete_and_exit(&ctrl_complete, 0);
}

/*
 * Dispose the control loops when tearing down
 */
static void dispose_control_loops(void)
{
        dispose_cpu_state(&cpu_state[0]);
        dispose_cpu_state(&cpu_state[1]);

        dispose_backside_state(&backside_state);
        dispose_drives_state(&drives_state);
}

/*
 * Create the control loops. U3-0 i2c bus is up, so we can now
 * get to the various sensors
 */
static int create_control_loops(void)
{
        struct device_node *np;

        /* Count CPUs from the device-tree, we don't care how many are
         * actually used by Linux
         */
        cpu_count = 0;
        for (np = NULL; NULL != (np = of_find_node_by_type(np, "cpu"));)
                cpu_count++;

        DBG("counted %d CPUs in the device-tree\n", cpu_count);

        /* Create control loops for everything. If any fail, everything
         * fails
         */
        if (init_cpu_state(&cpu_state[0], 0))
                goto fail;
        if (cpu_count > 1 && init_cpu_state(&cpu_state[1], 1))
                goto fail;
        if (init_backside_state(&backside_state))
                goto fail;
        if (init_drives_state(&drives_state))
                goto fail;

        DBG("all control loops up !\n");

        return 0;
        
 fail:
        DBG("failure creating control loops, disposing\n");

        dispose_control_loops();

        return -ENODEV;
}

/*
 * Start the control loops after everything is up, that is create
 * the thread that will make them run
 */
static void start_control_loops(void)
{
        init_completion(&ctrl_complete);

        ctrl_task = kernel_thread(main_control_loop, NULL, SIGCHLD | CLONE_KERNEL);
}

/*
 * Stop the control loops when tearing down
 */
static void stop_control_loops(void)
{
        if (ctrl_task != 0)
                wait_for_completion(&ctrl_complete);
}

/*
 * Attach to the i2c FCU after detecting U3-1 bus
 */
static int attach_fcu(void)
{
        fcu = attach_i2c_chip(FAN_CTRLER_ID, "fcu");
        if (fcu == NULL)
                return -ENODEV;

        DBG("FCU attached\n");

        return 0;
}

/*
 * Detach from the i2c FCU when tearing down
 */
static void detach_fcu(void)
{
        if (fcu)
                detach_i2c_chip(fcu);
        fcu = NULL;
}

/*
 * Attach to the i2c controller. We probe the various chips based
 * on the device-tree nodes and build everything for the driver to
 * run, we then kick the driver monitoring thread
 */
static int therm_pm72_attach(struct i2c_adapter *adapter)
{
        down(&driver_lock);

        /* Check state */
        if (state == state_detached)
                state = state_attaching;
        if (state != state_attaching) {
                up(&driver_lock);
                return 0;
        }

        /* Check if we are looking for one of these */
        if (u3_0 == NULL && !strcmp(adapter->name, "u3 0")) {
                u3_0 = adapter;
                DBG("found U3-0, creating control loops\n");
                if (create_control_loops())
                        u3_0 = NULL;
        } else if (u3_1 == NULL && !strcmp(adapter->name, "u3 1")) {
                u3_1 = adapter;
                DBG("found U3-1, attaching FCU\n");
                if (attach_fcu())
                        u3_1 = NULL;
        }
        /* We got all we need, start control loops */
        if (u3_0 != NULL && u3_1 != NULL) {
                DBG("everything up, starting control loops\n");
                state = state_attached;
                start_control_loops();
        }
        up(&driver_lock);

        return 0;
}

/*
 * Called on every adapter when the driver or the i2c controller
 * is going away.
 */
static int therm_pm72_detach(struct i2c_adapter *adapter)
{
        down(&driver_lock);

        if (state != state_detached)
                state = state_detaching;

        /* Stop control loops if any */
        DBG("stopping control loops\n");
        up(&driver_lock);
        stop_control_loops();
        down(&driver_lock);

        if (u3_0 != NULL && !strcmp(adapter->name, "u3 0")) {
                DBG("lost U3-0, disposing control loops\n");
                dispose_control_loops();
                u3_0 = NULL;
        }
        
        if (u3_1 != NULL && !strcmp(adapter->name, "u3 1")) {
                DBG("lost U3-1, detaching FCU\n");
                detach_fcu();
                u3_1 = NULL;
        }
        if (u3_0 == NULL && u3_1 == NULL)
                state = state_detached;

        up(&driver_lock);

        return 0;
}

static int fcu_of_probe(struct of_device* dev, const struct of_match *match)
{
        int rc;

        state = state_detached;

        rc = i2c_add_driver(&therm_pm72_driver);
        if (rc < 0)
                return rc;
        return 0;
}

static int fcu_of_remove(struct of_device* dev)
{
        i2c_del_driver(&therm_pm72_driver);

        return 0;
}

static struct of_match fcu_of_match[] = 
{
        {
        .name           = OF_ANY_MATCH,
        .type           = "fcu",
        .compatible     = OF_ANY_MATCH
        },
        {},
};

static struct of_platform_driver fcu_of_platform_driver = 
{
        .name           = "temperature",
        .match_table    = fcu_of_match,
        .probe          = fcu_of_probe,
        .remove         = fcu_of_remove
};

/*
 * Check machine type, attach to i2c controller
 */
static int __init therm_pm72_init(void)
{
        struct device_node *np;

        if (!machine_is_compatible("PowerMac7,2"))
                return -ENODEV;

        printk(KERN_INFO "PowerMac G5 Thermal control driver %s\n", VERSION);

        np = of_find_node_by_type(NULL, "fcu");
        if (np == NULL) {
                printk(KERN_ERR "Can't find FCU in device-tree !\n");
                return -ENODEV;
        }
        of_dev = of_platform_device_create(np, "temperature");
        if (of_dev == NULL) {
                printk(KERN_ERR "Can't register FCU platform device !\n");
                return -ENODEV;
        }

        of_register_driver(&fcu_of_platform_driver);
        
        return 0;
}

static void __exit therm_pm72_exit(void)
{
        of_unregister_driver(&fcu_of_platform_driver);

        if (of_dev)
                of_device_unregister(of_dev);
}

module_init(therm_pm72_init);
module_exit(therm_pm72_exit);

MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("Driver for Apple's PowerMac7,2 G5 thermal control");
MODULE_LICENSE("GPL");