/* bbc_envctrl.c: UltraSPARC-III environment control driver.
 *
 * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)
 */

#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/kmod.h>
#include <linux/reboot.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/of_device.h>
#include <asm/oplib.h>

#include "bbc_i2c.h"
#include "max1617.h"

#undef ENVCTRL_TRACE

/* WARNING: Making changes to this driver is very dangerous.
 *          If you misprogram the sensor chips they can
 *          cut the power on you instantly.
 */

/* Two temperature sensors exist in the SunBLADE-1000 enclosure.
 * Both are implemented using max1617 i2c devices.  Each max1617
 * monitors 2 temperatures, one for one of the cpu dies and the other
 * for the ambient temperature.
 *
 * The max1617 is capable of being programmed with power-off
 * temperature values, one low limit and one high limit.  These
 * can be controlled independently for the cpu or ambient temperature.
 * If a limit is violated, the power is simply shut off.  The frequency
 * with which the max1617 does temperature sampling can be controlled
 * as well.
 *
 * Three fans exist inside the machine, all three are controlled with
 * an i2c digital to analog converter.  There is a fan directed at the
 * two processor slots, another for the rest of the enclosure, and the
 * third is for the power supply.  The first two fans may be speed
 * controlled by changing the voltage fed to them.  The third fan may
 * only be completely off or on.  The third fan is meant to only be
 * disabled/enabled when entering/exiting the lowest power-saving
 * mode of the machine.
 *
 * An environmental control kernel thread periodically monitors all
 * temperature sensors.  Based upon the samples it will adjust the
 * fan speeds to try and keep the system within a certain temperature
 * range (the goal being to make the fans as quiet as possible without
 * allowing the system to get too hot).
 *
 * If the temperature begins to rise/fall outside of the acceptable
 * operating range, a periodic warning will be sent to the kernel log.
 * The fans will be put on full blast to attempt to deal with this
 * situation.  After exceeding the acceptable operating range by a
 * certain threshold, the kernel thread will shut down the system.
 * Here, the thread is attempting to shut the machine down cleanly
 * before the hardware based power-off event is triggered.
 */

/* These settings are in Celsius.  We use these defaults only
 * if we cannot interrogate the cpu-fru SEEPROM.
 */
struct temp_limits {
        s8 high_pwroff, high_shutdown, high_warn;
        s8 low_warn, low_shutdown, low_pwroff;
};

static struct temp_limits cpu_temp_limits[2] = {
        { 100, 85, 80, 5, -5, -10 },
        { 100, 85, 80, 5, -5, -10 },
};

static struct temp_limits amb_temp_limits[2] = {
        { 65, 55, 40, 5, -5, -10 },
        { 65, 55, 40, 5, -5, -10 },
};

static LIST_HEAD(all_temps);
static LIST_HEAD(all_fans);

#define CPU_FAN_REG     0xf0
#define SYS_FAN_REG     0xf2
#define PSUPPLY_FAN_REG 0xf4

#define FAN_SPEED_MIN   0x0c
#define FAN_SPEED_MAX   0x3f

#define PSUPPLY_FAN_ON  0x1f
#define PSUPPLY_FAN_OFF 0x00

static void set_fan_speeds(struct bbc_fan_control *fp)
{
        /* Put temperatures into range so we don't mis-program
         * the hardware.
         */
        if (fp->cpu_fan_speed < FAN_SPEED_MIN)
                fp->cpu_fan_speed = FAN_SPEED_MIN;
        if (fp->cpu_fan_speed > FAN_SPEED_MAX)
                fp->cpu_fan_speed = FAN_SPEED_MAX;
        if (fp->system_fan_speed < FAN_SPEED_MIN)
                fp->system_fan_speed = FAN_SPEED_MIN;
        if (fp->system_fan_speed > FAN_SPEED_MAX)
                fp->system_fan_speed = FAN_SPEED_MAX;
#ifdef ENVCTRL_TRACE
        printk("fan%d: Changed fan speed to cpu(%02x) sys(%02x)\n",
               fp->index,
               fp->cpu_fan_speed, fp->system_fan_speed);
#endif

        bbc_i2c_writeb(fp->client, fp->cpu_fan_speed, CPU_FAN_REG);
        bbc_i2c_writeb(fp->client, fp->system_fan_speed, SYS_FAN_REG);
        bbc_i2c_writeb(fp->client,
                       (fp->psupply_fan_on ?
                        PSUPPLY_FAN_ON : PSUPPLY_FAN_OFF),
                       PSUPPLY_FAN_REG);
}

static void get_current_temps(struct bbc_cpu_temperature *tp)
{
        tp->prev_amb_temp = tp->curr_amb_temp;
        bbc_i2c_readb(tp->client,
                      (unsigned char *) &tp->curr_amb_temp,
                      MAX1617_AMB_TEMP);
        tp->prev_cpu_temp = tp->curr_cpu_temp;
        bbc_i2c_readb(tp->client,
                      (unsigned char *) &tp->curr_cpu_temp,
                      MAX1617_CPU_TEMP);
#ifdef ENVCTRL_TRACE
        printk("temp%d: cpu(%d C) amb(%d C)\n",
               tp->index,
               (int) tp->curr_cpu_temp, (int) tp->curr_amb_temp);
#endif
}


static void do_envctrl_shutdown(struct bbc_cpu_temperature *tp)
{
        static int shutting_down = 0;
        char *type = "???";
        s8 val = -1;

        if (shutting_down != 0)
                return;

        if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
            tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
                type = "ambient";
                val = tp->curr_amb_temp;
        } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
                   tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
                type = "CPU";
                val = tp->curr_cpu_temp;
        }

        printk(KERN_CRIT "temp%d: Outside of safe %s "
               "operating temperature, %d C.\n",
               tp->index, type, val);

        printk(KERN_CRIT "kenvctrld: Shutting down the system now.\n");

        shutting_down = 1;
        if (orderly_poweroff(true) < 0)
                printk(KERN_CRIT "envctrl: shutdown execution failed\n");
}

#define WARN_INTERVAL   (30 * HZ)

static void analyze_ambient_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
{
        int ret = 0;

        if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
                if (tp->curr_amb_temp >=
                    amb_temp_limits[tp->index].high_warn) {
                        printk(KERN_WARNING "temp%d: "
                               "Above safe ambient operating temperature, %d C.\n",
                               tp->index, (int) tp->curr_amb_temp);
                        ret = 1;
                } else if (tp->curr_amb_temp <
                           amb_temp_limits[tp->index].low_warn) {
                        printk(KERN_WARNING "temp%d: "
                               "Below safe ambient operating temperature, %d C.\n",
                               tp->index, (int) tp->curr_amb_temp);
                        ret = 1;
                }
                if (ret)
                        *last_warn = jiffies;
        } else if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_warn ||
                   tp->curr_amb_temp < amb_temp_limits[tp->index].low_warn)
                ret = 1;

        /* Now check the shutdown limits. */
        if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
            tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
                do_envctrl_shutdown(tp);
                ret = 1;
        }

        if (ret) {
                tp->fan_todo[FAN_AMBIENT] = FAN_FULLBLAST;
        } else if ((tick & (8 - 1)) == 0) {
                s8 amb_goal_hi = amb_temp_limits[tp->index].high_warn - 10;
                s8 amb_goal_lo;

                amb_goal_lo = amb_goal_hi - 3;

                /* We do not try to avoid 'too cold' events.  Basically we
                 * only try to deal with over-heating and fan noise reduction.
                 */
                if (tp->avg_amb_temp < amb_goal_hi) {
                        if (tp->avg_amb_temp >= amb_goal_lo)
                                tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
                        else
                                tp->fan_todo[FAN_AMBIENT] = FAN_SLOWER;
                } else {
                        tp->fan_todo[FAN_AMBIENT] = FAN_FASTER;
                }
        } else {
                tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
        }
}

static void analyze_cpu_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
{
        int ret = 0;

        if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
                if (tp->curr_cpu_temp >=
                    cpu_temp_limits[tp->index].high_warn) {
                        printk(KERN_WARNING "temp%d: "
                               "Above safe CPU operating temperature, %d C.\n",
                               tp->index, (int) tp->curr_cpu_temp);
                        ret = 1;
                } else if (tp->curr_cpu_temp <
                           cpu_temp_limits[tp->index].low_warn) {
                        printk(KERN_WARNING "temp%d: "
                               "Below safe CPU operating temperature, %d C.\n",
                               tp->index, (int) tp->curr_cpu_temp);
                        ret = 1;
                }
                if (ret)
                        *last_warn = jiffies;
        } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_warn ||
                   tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_warn)
                ret = 1;

        /* Now check the shutdown limits. */
        if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
            tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
                do_envctrl_shutdown(tp);
                ret = 1;
        }

        if (ret) {
                tp->fan_todo[FAN_CPU] = FAN_FULLBLAST;
        } else if ((tick & (8 - 1)) == 0) {
                s8 cpu_goal_hi = cpu_temp_limits[tp->index].high_warn - 10;
                s8 cpu_goal_lo;

                cpu_goal_lo = cpu_goal_hi - 3;

                /* We do not try to avoid 'too cold' events.  Basically we
                 * only try to deal with over-heating and fan noise reduction.
                 */
                if (tp->avg_cpu_temp < cpu_goal_hi) {
                        if (tp->avg_cpu_temp >= cpu_goal_lo)
                                tp->fan_todo[FAN_CPU] = FAN_SAME;
                        else
                                tp->fan_todo[FAN_CPU] = FAN_SLOWER;
                } else {
                        tp->fan_todo[FAN_CPU] = FAN_FASTER;
                }
        } else {
                tp->fan_todo[FAN_CPU] = FAN_SAME;
        }
}

static void analyze_temps(struct bbc_cpu_temperature *tp, unsigned long *last_warn)
{
        tp->avg_amb_temp = (s8)((int)((int)tp->avg_amb_temp + (int)tp->curr_amb_temp) / 2);
        tp->avg_cpu_temp = (s8)((int)((int)tp->avg_cpu_temp + (int)tp->curr_cpu_temp) / 2);

        analyze_ambient_temp(tp, last_warn, tp->sample_tick);
        analyze_cpu_temp(tp, last_warn, tp->sample_tick);

        tp->sample_tick++;
}

static enum fan_action prioritize_fan_action(int which_fan)
{
        struct bbc_cpu_temperature *tp;
        enum fan_action decision = FAN_STATE_MAX;

        /* Basically, prioritize what the temperature sensors
         * recommend we do, and perform that action on all the
         * fans.
         */
        list_for_each_entry(tp, &all_temps, glob_list) {
                if (tp->fan_todo[which_fan] == FAN_FULLBLAST) {
                        decision = FAN_FULLBLAST;
                        break;
                }
                if (tp->fan_todo[which_fan] == FAN_SAME &&
                    decision != FAN_FASTER)
                        decision = FAN_SAME;
                else if (tp->fan_todo[which_fan] == FAN_FASTER)
                        decision = FAN_FASTER;
                else if (decision != FAN_FASTER &&
                         decision != FAN_SAME &&
                         tp->fan_todo[which_fan] == FAN_SLOWER)
                        decision = FAN_SLOWER;
        }
        if (decision == FAN_STATE_MAX)
                decision = FAN_SAME;

        return decision;
}

static int maybe_new_ambient_fan_speed(struct bbc_fan_control *fp)
{
        enum fan_action decision = prioritize_fan_action(FAN_AMBIENT);
        int ret;

        if (decision == FAN_SAME)
                return 0;

        ret = 1;
        if (decision == FAN_FULLBLAST) {
                if (fp->system_fan_speed >= FAN_SPEED_MAX)
                        ret = 0;
                else
                        fp->system_fan_speed = FAN_SPEED_MAX;
        } else {
                if (decision == FAN_FASTER) {
                        if (fp->system_fan_speed >= FAN_SPEED_MAX)
                                ret = 0;
                        else
                                fp->system_fan_speed += 2;
                } else {
                        int orig_speed = fp->system_fan_speed;

                        if (orig_speed <= FAN_SPEED_MIN ||
                            orig_speed <= (fp->cpu_fan_speed - 3))
                                ret = 0;
                        else
                                fp->system_fan_speed -= 1;
                }
        }

        return ret;
}

static int maybe_new_cpu_fan_speed(struct bbc_fan_control *fp)
{
        enum fan_action decision = prioritize_fan_action(FAN_CPU);
        int ret;

        if (decision == FAN_SAME)
                return 0;

        ret = 1;
        if (decision == FAN_FULLBLAST) {
                if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
                        ret = 0;
                else
                        fp->cpu_fan_speed = FAN_SPEED_MAX;
        } else {
                if (decision == FAN_FASTER) {
                        if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
                                ret = 0;
                        else {
                                fp->cpu_fan_speed += 2;
                                if (fp->system_fan_speed <
                                    (fp->cpu_fan_speed - 3))
                                        fp->system_fan_speed =
                                                fp->cpu_fan_speed - 3;
                        }
                } else {
                        if (fp->cpu_fan_speed <= FAN_SPEED_MIN)
                                ret = 0;
                        else
                                fp->cpu_fan_speed -= 1;
                }
        }

        return ret;
}

static void maybe_new_fan_speeds(struct bbc_fan_control *fp)
{
        int new;

        new  = maybe_new_ambient_fan_speed(fp);
        new |= maybe_new_cpu_fan_speed(fp);

        if (new)
                set_fan_speeds(fp);
}

static void fans_full_blast(void)
{
        struct bbc_fan_control *fp;

        /* Since we will not be monitoring things anymore, put
         * the fans on full blast.
         */
        list_for_each_entry(fp, &all_fans, glob_list) {
                fp->cpu_fan_speed = FAN_SPEED_MAX;
                fp->system_fan_speed = FAN_SPEED_MAX;
                fp->psupply_fan_on = 1;
                set_fan_speeds(fp);
        }
}

#define POLL_INTERVAL   (5 * 1000)
static unsigned long last_warning_jiffies;
static struct task_struct *kenvctrld_task;

static int kenvctrld(void *__unused)
{
        printk(KERN_INFO "bbc_envctrl: kenvctrld starting...\n");
        last_warning_jiffies = jiffies - WARN_INTERVAL;
        for (;;) {
                struct bbc_cpu_temperature *tp;
                struct bbc_fan_control *fp;

                msleep_interruptible(POLL_INTERVAL);
                if (kthread_should_stop())
                        break;

                list_for_each_entry(tp, &all_temps, glob_list) {
                        get_current_temps(tp);
                        analyze_temps(tp, &last_warning_jiffies);
                }
                list_for_each_entry(fp, &all_fans, glob_list)
                        maybe_new_fan_speeds(fp);
        }
        printk(KERN_INFO "bbc_envctrl: kenvctrld exiting...\n");

        fans_full_blast();

        return 0;
}

static void attach_one_temp(struct bbc_i2c_bus *bp, struct platform_device *op,
                            int temp_idx)
{
        struct bbc_cpu_temperature *tp;

        tp = kzalloc(sizeof(*tp), GFP_KERNEL);
        if (!tp)
                return;

        tp->client = bbc_i2c_attach(bp, op);
        if (!tp->client) {
                kfree(tp);
                return;
        }


        tp->index = temp_idx;

        list_add(&tp->glob_list, &all_temps);
        list_add(&tp->bp_list, &bp->temps);

        /* Tell it to convert once every 5 seconds, clear all cfg
         * bits.
         */
        bbc_i2c_writeb(tp->client, 0x00, MAX1617_WR_CFG_BYTE);
        bbc_i2c_writeb(tp->client, 0x02, MAX1617_WR_CVRATE_BYTE);

        /* Program the hard temperature limits into the chip. */
        bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].high_pwroff,
                       MAX1617_WR_AMB_HIGHLIM);
        bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].low_pwroff,
                       MAX1617_WR_AMB_LOWLIM);
        bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].high_pwroff,
                       MAX1617_WR_CPU_HIGHLIM);
        bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].low_pwroff,
                       MAX1617_WR_CPU_LOWLIM);

        get_current_temps(tp);
        tp->prev_cpu_temp = tp->avg_cpu_temp = tp->curr_cpu_temp;
        tp->prev_amb_temp = tp->avg_amb_temp = tp->curr_amb_temp;

        tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
        tp->fan_todo[FAN_CPU] = FAN_SAME;
}

static void attach_one_fan(struct bbc_i2c_bus *bp, struct platform_device *op,
                           int fan_idx)
{
        struct bbc_fan_control *fp;

        fp = kzalloc(sizeof(*fp), GFP_KERNEL);
        if (!fp)
                return;

        fp->client = bbc_i2c_attach(bp, op);
        if (!fp->client) {
                kfree(fp);
                return;
        }

        fp->index = fan_idx;

        list_add(&fp->glob_list, &all_fans);
        list_add(&fp->bp_list, &bp->fans);

        /* The i2c device controlling the fans is write-only.
         * So the only way to keep track of the current power
         * level fed to the fans is via software.  Choose half
         * power for cpu/system and 'on' fo the powersupply fan
         * and set it now.
         */
        fp->psupply_fan_on = 1;
        fp->cpu_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
        fp->cpu_fan_speed += FAN_SPEED_MIN;
        fp->system_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
        fp->system_fan_speed += FAN_SPEED_MIN;

        set_fan_speeds(fp);
}

static void destroy_one_temp(struct bbc_cpu_temperature *tp)
{
        bbc_i2c_detach(tp->client);
        kfree(tp);
}

static void destroy_all_temps(struct bbc_i2c_bus *bp)
{
        struct bbc_cpu_temperature *tp, *tpos;

        list_for_each_entry_safe(tp, tpos, &bp->temps, bp_list) {
                list_del(&tp->bp_list);
                list_del(&tp->glob_list);
                destroy_one_temp(tp);
        }
}

static void destroy_one_fan(struct bbc_fan_control *fp)
{
        bbc_i2c_detach(fp->client);
        kfree(fp);
}

static void destroy_all_fans(struct bbc_i2c_bus *bp)
{
        struct bbc_fan_control *fp, *fpos;

        list_for_each_entry_safe(fp, fpos, &bp->fans, bp_list) {
                list_del(&fp->bp_list);
                list_del(&fp->glob_list);
                destroy_one_fan(fp);
        }
}

int bbc_envctrl_init(struct bbc_i2c_bus *bp)
{
        struct platform_device *op;
        int temp_index = 0;
        int fan_index = 0;
        int devidx = 0;

        while ((op = bbc_i2c_getdev(bp, devidx++)) != NULL) {
                if (!strcmp(op->dev.of_node->name, "temperature"))
                        attach_one_temp(bp, op, temp_index++);
                if (!strcmp(op->dev.of_node->name, "fan-control"))
                        attach_one_fan(bp, op, fan_index++);
        }
        if (temp_index != 0 && fan_index != 0) {
                kenvctrld_task = kthread_run(kenvctrld, NULL, "kenvctrld");
                if (IS_ERR(kenvctrld_task)) {
                        int err = PTR_ERR(kenvctrld_task);

                        kenvctrld_task = NULL;
                        destroy_all_temps(bp);
                        destroy_all_fans(bp);
                        return err;
                }
        }

        return 0;
}

void bbc_envctrl_cleanup(struct bbc_i2c_bus *bp)
{
        if (kenvctrld_task)
                kthread_stop(kenvctrld_task);

        destroy_all_temps(bp);
        destroy_all_fans(bp);
}