mraa/src/pwm/pwm.c

/*
 * Author: Thomas Ingleby <thomas.c.ingleby@intel.com>
 * Copyright (c) 2014 Intel Corporation.
 *
 * 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 AUTHORS OR COPYRIGHT HOLDERS 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.
 */

#include <stdlib.h>

#include "pwm.h"

/**
 * A strucutre representing a PWM pin
 */
struct _pwm {
    /*@{*/
    int pin; /**< the pin number, as known to the os. */
    int chipid; /**< the chip id, which the pwm resides */
    FILE *duty_fp; /**< File pointer to duty file */
    /*@}*/
};

static int
maa_pwm_setup_duty_fp(maa_pwm_context dev)
{
    char bu[64];
    sprintf(bu, "/sys/class/pwm/pwmchip%d/pwm%d/duty_cycle", dev->chipid, dev->pin);

    if ((dev->duty_fp = fopen(bu, "r+b")) == NULL) {
        return 1;
    }
    return 0;
}

static maa_result_t
maa_pwm_write_period(maa_pwm_context dev, int period)
{
    FILE *period_f;
    char bu[64];
    sprintf(bu, "/sys/class/pwm/pwmchip%d/pwm%d/period", dev->chipid, dev->pin);

    if ((period_f = fopen(bu, "r+b")) == NULL) {
        fprintf(stderr, "Failed to open period for writing!\n");
        return MAA_ERROR_INVALID_RESOURCE;
    }
    fprintf(period_f, "%d", period);
    fclose(period_f);
    if (ferror(period_f) != 0)
        return MAA_ERROR_INVALID_RESOURCE;
    return MAA_SUCCESS;
}

static maa_result_t
maa_pwm_write_duty(maa_pwm_context dev, int duty)
{
    if (dev->duty_fp == NULL) {
        maa_pwm_setup_duty_fp(dev);
    }
    fprintf(dev->duty_fp, "%d", duty);
    rewind(dev->duty_fp);
    fflush(dev->duty_fp);
     if (ferror(dev->duty_fp) != 0)
        return MAA_ERROR_INVALID_RESOURCE;
    return MAA_SUCCESS;
}

static int
maa_pwm_get_period(maa_pwm_context dev)
{
    FILE *period_f;
    char bu[64];
    char output[16];

    sprintf(bu, "/sys/class/pwm/pwmchip%d/pwm%d/period", dev->chipid, dev->pin);
    if ((period_f = fopen(bu, "rb")) == NULL) {
        fprintf(stderr, "Failed to open period for reading!\n");
        return 0;
    }
    fgets(output, 16, period_f);
    fclose(period_f);
    return atoi(output);
}

static int
maa_pwm_get_duty(maa_pwm_context dev)
{
    if (dev->duty_fp == NULL) {
        maa_pwm_setup_duty_fp(dev);
    }
    char output[16];
    fgets(output, 16, dev->duty_fp);
    fseek(dev->duty_fp, SEEK_SET, 0);
    return atoi(output);
}

maa_pwm_context
maa_pwm_init(int pin) {
    maa_pin_t* pinm = maa_check_pwm(pin);
    if (pinm == NULL)
        return NULL;
    int chip = pinm->parent_id;
    int pinn = pinm->pinmap;
    free(pinm);
    return maa_pwm_init_raw(chip,pinn);
}

maa_pwm_context
maa_pwm_init_raw(int chipin, int pin)
{
    maa_pwm_context dev = (maa_pwm_context) malloc(sizeof(struct _pwm));
    if (dev == NULL)
        return NULL;

    dev->chipid = chipin;
    dev->pin = pin;

    FILE *export_f;
    char buffer[64];
    snprintf(buffer, 64, "/sys/class/pwm/pwmchip%d/export", dev->chipid);

    if ((export_f = fopen(buffer, "w")) == NULL) {
        fprintf(stderr, "Failed to open export for writing!\n");
        free(dev);
        return NULL;
    } else {
        fprintf(export_f, "%d", dev->pin);
        fclose(export_f);
        maa_pwm_setup_duty_fp(dev);
    }
    return dev;
}

maa_result_t
maa_pwm_write(maa_pwm_context dev, float percentage)
{
   return maa_pwm_write_duty(dev, percentage * maa_pwm_get_period(dev));
}

float
maa_pwm_read(maa_pwm_context dev)
{
    float output = maa_pwm_get_duty(dev) / (float) maa_pwm_get_period(dev);
    return output;
}

maa_result_t
maa_pwm_period(maa_pwm_context dev, float seconds)
{
    return maa_pwm_period_ms(dev, seconds*1000);
}

maa_result_t
maa_pwm_period_ms(maa_pwm_context dev, int ms)
{
    return maa_pwm_period_us(dev, ms*1000);
}

maa_result_t
maa_pwm_period_us(maa_pwm_context dev, int us)
{
    return maa_pwm_write_period(dev, us*1000);
}

maa_result_t
maa_pwm_pulsewidth(maa_pwm_context dev, float seconds)
{
    return maa_pwm_pulsewidth_ms(dev, seconds*1000);
}

maa_result_t
maa_pwm_pulsewidth_ms(maa_pwm_context dev, int ms)
{
    return maa_pwm_pulsewidth_us(dev, ms*1000);
}

maa_result_t
maa_pwm_pulsewidth_us(maa_pwm_context dev, int us)
{
    return maa_pwm_write_duty(dev, us*1000);
}

maa_result_t
maa_pwm_enable(maa_pwm_context dev, int enable)
{
    int status;
    if (enable != 0) {
        status = 1;
    } else {
        status = enable;
    }
    FILE *enable_f;
    char bu[64];
    sprintf(bu, "/sys/class/pwm/pwmchip%d/pwm%d/enable", dev->chipid, dev->pin);

    if ((enable_f = fopen(bu, "w")) == NULL) {
        fprintf(stderr, "Failed to open enable for writing!\n");
        return MAA_ERROR_INVALID_RESOURCE;
    }
    fprintf(enable_f, "%d", status);
    fclose(enable_f);
    if (ferror(enable_f) != 0)
        return MAA_ERROR_INVALID_RESOURCE;
    return MAA_SUCCESS;
}

maa_result_t
maa_pwm_unexport(maa_pwm_context dev)
{
    FILE *unexport_f;
    char buffer[64];
    snprintf(buffer, 64, "/sys/class/pwm/pwmchip%d/unexport", dev->chipid);

    if ((unexport_f = fopen(buffer, "w")) == NULL) {
        fprintf(stderr, "Failed to open unexport for writing!\n");
        return MAA_ERROR_INVALID_RESOURCE;
    }
    fprintf(unexport_f, "%d", dev->pin);
    fclose(unexport_f);
    if (ferror(unexport_f) != 0)
        return MAA_ERROR_INVALID_RESOURCE;
    return MAA_SUCCESS;
}

maa_result_t
maa_pwm_close(maa_pwm_context dev)
{
    maa_pwm_unexport(dev);
    free(dev);
    return MAA_SUCCESS;
}