pios_pwm.c

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/*
 * 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; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, see <http://www.gnu.org/licenses/>
 */

/* Project Includes */
#include "pios.h"
#include "pios_pwm_priv.h"

#if defined(PIOS_INCLUDE_PWM)

/* Provide a RCVR driver */
static int32_t PIOS_PWM_Get(uintptr_t rcvr_id, uint8_t channel);

const struct pios_rcvr_driver pios_pwm_rcvr_driver = {
        .read = PIOS_PWM_Get,
};

/* Local Variables */
/* 100 ms timeout without updates on channels */
const static uint32_t PWM_SUPERVISOR_TIMEOUT = 100000;
const static uint32_t PWM_CAPTURE_MAX = 3000;

enum pios_pwm_dev_magic {
        PIOS_PWM_DEV_MAGIC = 0xab30293c,
};

enum pios_pwm_capture_state {
        PIOS_PWM_CAPTURE_RISING,
        PIOS_PWM_CAPTURE_FALLING,
};

struct pios_pwm_dev {
        enum pios_pwm_dev_magic     magic;
        const struct pios_pwm_cfg * cfg;

        volatile enum pios_pwm_capture_state CaptureState[PIOS_PWM_NUM_INPUTS];
        volatile uint16_t RiseValue[PIOS_PWM_NUM_INPUTS];
        volatile uint32_t CaptureValue[PIOS_PWM_NUM_INPUTS];
        volatile uint32_t overflow_count[PIOS_PWM_NUM_INPUTS];
};

static bool PIOS_PWM_validate(struct pios_pwm_dev * pwm_dev)
{
        return (pwm_dev->magic == PIOS_PWM_DEV_MAGIC);
}

static struct pios_pwm_dev * PIOS_PWM_alloc(void)
{
        struct pios_pwm_dev * pwm_dev;

        pwm_dev = (struct pios_pwm_dev *)PIOS_malloc(sizeof(*pwm_dev));
        if (!pwm_dev) return(NULL);

        memset(pwm_dev, 0, sizeof(*pwm_dev));

        pwm_dev->magic = PIOS_PWM_DEV_MAGIC;
        return(pwm_dev);
}

static void PIOS_PWM_tim_overflow_cb (uintptr_t id, uintptr_t context, uint8_t channel, uint16_t count);
static void PIOS_PWM_tim_edge_cb (uintptr_t id, uintptr_t context, uint8_t channel, uint16_t count);
const static struct pios_tim_callbacks tim_callbacks = {
        .overflow = PIOS_PWM_tim_overflow_cb,
        .edge     = PIOS_PWM_tim_edge_cb,
};

int32_t PIOS_PWM_Init(uintptr_t * pwm_id, const struct pios_pwm_cfg * cfg)
{
        PIOS_DEBUG_Assert(pwm_id);
        PIOS_DEBUG_Assert(cfg);

        struct pios_pwm_dev * pwm_dev;

        pwm_dev = (struct pios_pwm_dev *) PIOS_PWM_alloc();
        if (!pwm_dev) goto out_fail;

        /* Bind the configuration to the device instance */
        pwm_dev->cfg = cfg;

        for (uint8_t i = 0; i < PIOS_PWM_NUM_INPUTS; i++) {
                pwm_dev->CaptureValue[i] = PIOS_RCVR_TIMEOUT;
        }

        uintptr_t tim_id;
        if (PIOS_TIM_InitChannels(&tim_id, cfg->channels, cfg->num_channels, &tim_callbacks, (uintptr_t)pwm_dev)) {
                return -1;
        }

        /* Configure the channels to be in capture/compare mode */
        for (uint8_t i = 0; i < cfg->num_channels; i++) {
                const struct pios_tim_channel * chan = &cfg->channels[i];

                /* Configure timer for input capture */
                TIM_ICInitTypeDef TIM_ICInitStructure = cfg->tim_ic_init;
                TIM_ICInitStructure.TIM_Channel = chan->timer_chan;
                TIM_ICInit(chan->timer, &TIM_ICInitStructure);
                
                /* Enable the Capture Compare Interrupt Request */
                switch (chan->timer_chan) {
                case TIM_Channel_1:
                        TIM_ITConfig(chan->timer, TIM_IT_CC1, ENABLE);
                        break;
                case TIM_Channel_2:
                        TIM_ITConfig(chan->timer, TIM_IT_CC2, ENABLE);
                        break;
                case TIM_Channel_3:
                        TIM_ITConfig(chan->timer, TIM_IT_CC3, ENABLE);
                        break;
                case TIM_Channel_4:
                        TIM_ITConfig(chan->timer, TIM_IT_CC4, ENABLE);
                        break;
                }

                // Need the update event for that timer to detect timeouts
                TIM_ITConfig(chan->timer, TIM_IT_Update, ENABLE);

        }

        *pwm_id = (uintptr_t) pwm_dev;

        return (0);

out_fail:
        return (-1);
}

static int32_t PIOS_PWM_Get(uintptr_t rcvr_id, uint8_t channel)
{
        struct pios_pwm_dev * pwm_dev = (struct pios_pwm_dev *)rcvr_id;

        if (!PIOS_PWM_validate(pwm_dev)) {
                /* Invalid device specified */
                return PIOS_RCVR_INVALID;
        }

        if (channel >= PIOS_PWM_NUM_INPUTS) {
                /* Channel out of range */
                return PIOS_RCVR_INVALID;
        }
        return pwm_dev->CaptureValue[channel];
}

static void PIOS_PWM_tim_overflow_cb (uintptr_t tim_id, uintptr_t context, uint8_t channel, uint16_t count)
{
        struct pios_pwm_dev * pwm_dev = (struct pios_pwm_dev *)context;

        if (!PIOS_PWM_validate(pwm_dev)) {
                /* Invalid device specified */
                return;
        }

        if (channel >= pwm_dev->cfg->num_channels) {
                /* Channel out of range */
                return;
        }

        pwm_dev->overflow_count[channel]++;

        if (pwm_dev->overflow_count[channel] * count >= PWM_SUPERVISOR_TIMEOUT) {
                pwm_dev->CaptureState[channel] = PIOS_PWM_CAPTURE_RISING;
                pwm_dev->RiseValue[channel] = 0;
                pwm_dev->CaptureValue[channel] = PIOS_RCVR_TIMEOUT;
                pwm_dev->overflow_count[channel] = 0;
        }
}

static void PIOS_PWM_tim_edge_cb (uintptr_t tim_id, uintptr_t context, uint8_t chan_idx, uint16_t count)
{
        /* Recover our device context */
        struct pios_pwm_dev * pwm_dev = (struct pios_pwm_dev *)context;

        if (!PIOS_PWM_validate(pwm_dev)) {
                /* Invalid device specified */
                return;
        }

        if (chan_idx >= pwm_dev->cfg->num_channels) {
                /* Channel out of range */
                return;
        }

        const struct pios_tim_channel * chan = &pwm_dev->cfg->channels[chan_idx];
                        
        // flip state machine and capture value here
        /* Simple rise or fall state machine */
        TIM_ICInitTypeDef TIM_ICInitStructure = pwm_dev->cfg->tim_ic_init;
        if (pwm_dev->CaptureState[chan_idx] == PIOS_PWM_CAPTURE_RISING) {
                pwm_dev->RiseValue[chan_idx] = count;
                pwm_dev->overflow_count[chan_idx] = 0;

                /* Switch states */
                pwm_dev->CaptureState[chan_idx] = PIOS_PWM_CAPTURE_FALLING;

                /* Switch polarity of input capture */
                TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;
                TIM_ICInitStructure.TIM_Channel = chan->timer_chan;
                TIM_ICInit(chan->timer, &TIM_ICInitStructure);
        } else {
                uint16_t fall_value = count;

                uint32_t value = fall_value - pwm_dev->RiseValue[chan_idx];
                /* Capture computation */
                if (pwm_dev->overflow_count[chan_idx] > 1 || fall_value > pwm_dev->RiseValue[chan_idx])
                        value += pwm_dev->overflow_count[chan_idx] * chan->timer->ARR;

                if (value <= PWM_CAPTURE_MAX) {
                        pwm_dev->CaptureValue[chan_idx] = value;
                        pwm_dev->overflow_count[chan_idx] = 0;
                }

                /* Switch states */
                pwm_dev->CaptureState[chan_idx] = PIOS_PWM_CAPTURE_RISING;

                /* Switch polarity of input capture */
                TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
                TIM_ICInitStructure.TIM_Channel = chan->timer_chan;
                TIM_ICInit(chan->timer, &TIM_ICInitStructure);
        }
}

#endif