/*
 * Copyright 2012 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: Ben Skeggs
 *          Martin Peres
 */
#include "priv.h"

#include <subdev/bios/fan.h>
#include <subdev/gpio.h>
#include <subdev/timer.h>

static int
nvkm_fan_update(struct nvkm_fan *fan, bool immediate, int target)
{
        struct nvkm_therm *therm = fan->parent;
        struct nvkm_subdev *subdev = &therm->subdev;
        struct nvkm_timer *tmr = subdev->device->timer;
        unsigned long flags;
        int ret = 0;
        int duty;

        /* update target fan speed, restricting to allowed range */
        spin_lock_irqsave(&fan->lock, flags);
        if (target < 0)
                target = fan->percent;
        target = max_t(u8, target, fan->bios.min_duty);
        target = min_t(u8, target, fan->bios.max_duty);
        if (fan->percent != target) {
                nvkm_debug(subdev, "FAN target: %d\n", target);
                fan->percent = target;
        }

        /* check that we're not already at the target duty cycle */
        duty = fan->get(therm);
        if (duty == target) {
                spin_unlock_irqrestore(&fan->lock, flags);
                return 0;
        }

        /* smooth out the fanspeed increase/decrease */
        if (!immediate && duty >= 0) {
                /* the constant "3" is a rough approximation taken from
                 * nvidia's behaviour.
                 * it is meant to bump the fan speed more incrementally
                 */
                if (duty < target)
                        duty = min(duty + 3, target);
                else if (duty > target)
                        duty = max(duty - 3, target);
        } else {
                duty = target;
        }

        nvkm_debug(subdev, "FAN update: %d\n", duty);
        ret = fan->set(therm, duty);
        if (ret) {
                spin_unlock_irqrestore(&fan->lock, flags);
                return ret;
        }

        /* fan speed updated, drop the fan lock before grabbing the
         * alarm-scheduling lock and risking a deadlock
         */
        spin_unlock_irqrestore(&fan->lock, flags);

        /* schedule next fan update, if not at target speed already */
        if (target != duty) {
                u16 bump_period = fan->bios.bump_period;
                u16 slow_down_period = fan->bios.slow_down_period;
                u64 delay;

                if (duty > target)
                        delay = slow_down_period;
                else if (duty == target)
                        delay = min(bump_period, slow_down_period) ;
                else
                        delay = bump_period;

                nvkm_timer_alarm(tmr, delay * 1000 * 1000, &fan->alarm);
        }

        return ret;
}

static void
nvkm_fan_alarm(struct nvkm_alarm *alarm)
{
        struct nvkm_fan *fan = container_of(alarm, struct nvkm_fan, alarm);
        nvkm_fan_update(fan, false, -1);
}

int
nvkm_therm_fan_get(struct nvkm_therm *therm)
{
        return therm->fan->get(therm);
}

int
nvkm_therm_fan_set(struct nvkm_therm *therm, bool immediate, int percent)
{
        return nvkm_fan_update(therm->fan, immediate, percent);
}

int
nvkm_therm_fan_sense(struct nvkm_therm *therm)
{
        struct nvkm_device *device = therm->subdev.device;
        struct nvkm_timer *tmr = device->timer;
        struct nvkm_gpio *gpio = device->gpio;
        u32 cycles, cur, prev;
        u64 start, end, tach;

        if (therm->func->fan_sense)
                return therm->func->fan_sense(therm);

        if (therm->fan->tach.func == DCB_GPIO_UNUSED)
                return -ENODEV;

        /* Time a complete rotation and extrapolate to RPM:
         * When the fan spins, it changes the value of GPIO FAN_SENSE.
         * We get 4 changes (0 -> 1 -> 0 -> 1) per complete rotation.
         */
        start = nvkm_timer_read(tmr);
        prev = nvkm_gpio_get(gpio, 0, therm->fan->tach.func,
                                      therm->fan->tach.line);
        cycles = 0;
        do {
                usleep_range(500, 1000); /* supports 0 < rpm < 7500 */

                cur = nvkm_gpio_get(gpio, 0, therm->fan->tach.func,
                                             therm->fan->tach.line);
                if (prev != cur) {
                        if (!start)
                                start = nvkm_timer_read(tmr);
                        cycles++;
                        prev = cur;
                }
        } while (cycles < 5 && nvkm_timer_read(tmr) - start < 250000000);
        end = nvkm_timer_read(tmr);

        if (cycles == 5) {
                tach = (u64)60000000000ULL;
                do_div(tach, (end - start));
                return tach;
        } else
                return 0;
}

int
nvkm_therm_fan_user_get(struct nvkm_therm *therm)
{
        return nvkm_therm_fan_get(therm);
}

int
nvkm_therm_fan_user_set(struct nvkm_therm *therm, int percent)
{
        if (therm->mode != NVKM_THERM_CTRL_MANUAL)
                return -EINVAL;

        return nvkm_therm_fan_set(therm, true, percent);
}

static void
nvkm_therm_fan_set_defaults(struct nvkm_therm *therm)
{
        therm->fan->bios.pwm_freq = 0;
        therm->fan->bios.min_duty = 0;
        therm->fan->bios.max_duty = 100;
        therm->fan->bios.bump_period = 500;
        therm->fan->bios.slow_down_period = 2000;
        therm->fan->bios.linear_min_temp = 40;
        therm->fan->bios.linear_max_temp = 85;
}

static void
nvkm_therm_fan_safety_checks(struct nvkm_therm *therm)
{
        if (therm->fan->bios.min_duty > 100)
                therm->fan->bios.min_duty = 100;
        if (therm->fan->bios.max_duty > 100)
                therm->fan->bios.max_duty = 100;

        if (therm->fan->bios.min_duty > therm->fan->bios.max_duty)
                therm->fan->bios.min_duty = therm->fan->bios.max_duty;
}

int
nvkm_therm_fan_init(struct nvkm_therm *therm)
{
        return 0;
}

int
nvkm_therm_fan_fini(struct nvkm_therm *therm, bool suspend)
{
        struct nvkm_timer *tmr = therm->subdev.device->timer;
        if (suspend)
                nvkm_timer_alarm(tmr, 0, &therm->fan->alarm);
        return 0;
}

int
nvkm_therm_fan_ctor(struct nvkm_therm *therm)
{
        struct nvkm_subdev *subdev = &therm->subdev;
        struct nvkm_device *device = subdev->device;
        struct nvkm_gpio *gpio = device->gpio;
        struct nvkm_bios *bios = device->bios;
        struct dcb_gpio_func func;
        int ret;

        /* attempt to locate a drivable fan, and determine control method */
        ret = nvkm_gpio_find(gpio, 0, DCB_GPIO_FAN, 0xff, &func);
        if (ret == 0) {
                /* FIXME: is this really the place to perform such checks ? */
                if (func.line != 16 && func.log[0] & DCB_GPIO_LOG_DIR_IN) {
                        nvkm_debug(subdev, "GPIO_FAN is in input mode\n");
                        ret = -EINVAL;
                } else {
                        ret = nvkm_fanpwm_create(therm, &func);
                        if (ret != 0)
                                ret = nvkm_fantog_create(therm, &func);
                }
        }

        /* no controllable fan found, create a dummy fan module */
        if (ret != 0) {
                ret = nvkm_fannil_create(therm);
                if (ret)
                        return ret;
        }

        nvkm_debug(subdev, "FAN control: %s\n", therm->fan->type);

        /* read the current speed, it is useful when resuming */
        therm->fan->percent = nvkm_therm_fan_get(therm);

        /* attempt to detect a tachometer connection */
        ret = nvkm_gpio_find(gpio, 0, DCB_GPIO_FAN_SENSE, 0xff,
                             &therm->fan->tach);
        if (ret)
                therm->fan->tach.func = DCB_GPIO_UNUSED;

        /* initialise fan bump/slow update handling */
        therm->fan->parent = therm;
        nvkm_alarm_init(&therm->fan->alarm, nvkm_fan_alarm);
        spin_lock_init(&therm->fan->lock);

        /* other random init... */
        nvkm_therm_fan_set_defaults(therm);
        nvbios_perf_fan_parse(bios, &therm->fan->perf);
        if (!nvbios_fan_parse(bios, &therm->fan->bios)) {
                nvkm_debug(subdev, "parsing the fan table failed\n");
                if (nvbios_therm_fan_parse(bios, &therm->fan->bios))
                        nvkm_error(subdev, "parsing both fan tables failed\n");
        }
        nvkm_therm_fan_safety_checks(therm);
        return 0;
}