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 <sys/stat.h>
#include <unistd.h>
#include <limits.h>

#include "pwm.h"
#include "mraa_internal.h"

#define MAX_SIZE 64
#define SYSFS_PWM "/sys/class/pwm"

static int
mraa_pwm_setup_duty_fp(mraa_pwm_context dev)
{
    char bu[MAX_SIZE];
    snprintf(bu, MAX_SIZE, "/sys/class/pwm/pwmchip%d/pwm%d/duty_cycle", dev->chipid, dev->pin);

    dev->duty_fp = open(bu, O_RDWR);
    if (dev->duty_fp == -1) {
        return 1;
    }
    return 0;
}

static mraa_result_t
mraa_pwm_write_period(mraa_pwm_context dev, int period)
{
    if (advance_func->pwm_period_replace != NULL) {
        mraa_result_t result = advance_func->pwm_period_replace(dev, period);
        if (result == MRAA_SUCCESS) {
            dev->period = period;
        }
        return result;
    }
    char bu[MAX_SIZE];
    snprintf(bu, MAX_SIZE, "/sys/class/pwm/pwmchip%d/pwm%d/period", dev->chipid, dev->pin);

    int period_f = open(bu, O_RDWR);
    if (period_f == -1) {
        syslog(LOG_ERR, "pwm: Failed to open period for writing");
        return MRAA_ERROR_INVALID_RESOURCE;
    }
    char out[MAX_SIZE];
    int length = snprintf(out, MAX_SIZE, "%d", period);
    if (write(period_f, out, length * sizeof(char)) == -1) {
        close(period_f);
        return MRAA_ERROR_INVALID_RESOURCE;
    }

    close(period_f);
    dev->period = period;
    return MRAA_SUCCESS;
}

static mraa_result_t
mraa_pwm_write_duty(mraa_pwm_context dev, int duty)
{
    if (dev->duty_fp == -1) {
        if (mraa_pwm_setup_duty_fp(dev) == 1) {
            return MRAA_ERROR_INVALID_HANDLE;
        }
    }
    char bu[64];
    int length = sprintf(bu, "%d", duty);
    if (write(dev->duty_fp, bu, length * sizeof(char)) == -1)
        return MRAA_ERROR_INVALID_RESOURCE;
    return MRAA_SUCCESS;
}

static int
mraa_pwm_read_period(mraa_pwm_context dev)
{
    char bu[MAX_SIZE];
    char output[MAX_SIZE];
    snprintf(bu, MAX_SIZE, "/sys/class/pwm/pwmchip%d/pwm%d/period", dev->chipid, dev->pin);

    int period_f = open(bu, O_RDWR);
    if (period_f == -1) {
        syslog(LOG_ERR, "pwm: Failed to open period for reading");
        return 0;
    }
    off_t size = lseek(period_f, 0, SEEK_END);
    lseek(period_f, 0, SEEK_SET);

    ssize_t rb = read(period_f, output, size + 1);
    close(period_f);

    if (rb < 0) {
        syslog(LOG_ERR, "pwm: Error in reading period");
        return -1;
    }

    char* endptr;
    long int ret = strtol(output, &endptr, 10);
    if ('\0' != *endptr && '\n' != *endptr) {
        syslog(LOG_ERR, "pwm: Error in string conversion");
        return -1;
    } else if (ret > INT_MAX || ret < INT_MIN) {
        syslog(LOG_ERR, "pwm: Number is invalid");
        return -1;
    }
    dev->period = (int) ret;
    return (int) ret;
}

static int
mraa_pwm_read_duty(mraa_pwm_context dev)
{
    if (dev->duty_fp == -1) {
        if (mraa_pwm_setup_duty_fp(dev) == 1) {
            return MRAA_ERROR_INVALID_HANDLE;
        }
    } else {
        lseek(dev->duty_fp, 0, SEEK_SET);
    }
    off_t size = lseek(dev->duty_fp, 0, SEEK_END);
    lseek(dev->duty_fp, 0, SEEK_SET);
    char output[MAX_SIZE];
    ssize_t rb = read(dev->duty_fp, output, size + 1);
    if (rb < 0) {
        syslog(LOG_ERR, "pwm: Error in reading duty");
        return -1;
    }

    char* endptr;
    long int ret = strtol(output, &endptr, 10);
    if ('\0' != *endptr && '\n' != *endptr) {
        syslog(LOG_ERR, "pwm: Error in string converstion");
        return -1;
    } else if (ret > INT_MAX || ret < INT_MIN) {
        syslog(LOG_ERR, "pwm: Number is invalid");
        return -1;
    }
    return (int) ret;
}

mraa_pwm_context
mraa_pwm_init(int pin)
{
    if (advance_func->pwm_init_pre != NULL) {
        if (advance_func->pwm_init_pre(pin) != MRAA_SUCCESS)
            return NULL;
    }
    if (plat == NULL) {
        syslog(LOG_ERR, "pwm: Platform Not Initialised");
        return NULL;
    }
    if (plat->pins[pin].capabilites.pwm != 1) {
        syslog(LOG_ERR, "pwm: pin not capable of pwm");
        return NULL;
    }

    if (plat->pins[pin].capabilites.gpio == 1) {
        // This deserves more investigation
        mraa_gpio_context mux_i;
        mux_i = mraa_gpio_init_raw(plat->pins[pin].gpio.pinmap);
        if (mux_i == NULL) {
            syslog(LOG_ERR, "pwm: error in gpio->pwm transition");
            return NULL;
        }
        if (mraa_gpio_dir(mux_i, MRAA_GPIO_OUT) != MRAA_SUCCESS) {
            syslog(LOG_ERR, "pwm: error in gpio->pwm transition");
            return NULL;
        }
        if (mraa_gpio_write(mux_i, 1) != MRAA_SUCCESS) {
            syslog(LOG_ERR, "pwm: error in gpio->pwm transition");
            return NULL;
        }
        if (mraa_gpio_close(mux_i) != MRAA_SUCCESS) {
            syslog(LOG_ERR, "pwm: error in gpio->pwm transition");
            return NULL;
        }
    }

    if (plat->pins[pin].pwm.mux_total > 0) {
        if (mraa_setup_mux_mapped(plat->pins[pin].pwm) != MRAA_SUCCESS) {
            syslog(LOG_ERR, "pwm: Failed to set-up multiplexer");
            return NULL;
        }
    }

    int chip = plat->pins[pin].pwm.parent_id;
    int pinn = plat->pins[pin].pwm.pinmap;

    if (advance_func->pwm_init_post != NULL) {
        mraa_pwm_context pret = mraa_pwm_init_raw(chip, pinn);
        mraa_result_t ret = advance_func->pwm_init_post(pret);
        if (ret != MRAA_SUCCESS) {
            free(pret);
            return NULL;
        }
        return pret;
    }
    return mraa_pwm_init_raw(chip, pinn);
}

mraa_pwm_context
mraa_pwm_init_raw(int chipin, int pin)
{
    mraa_pwm_context dev = (mraa_pwm_context) malloc(sizeof(struct _pwm));
    if (dev == NULL)
        return NULL;
    dev->duty_fp = -1;
    dev->chipid = chipin;
    dev->pin = pin;
    dev->period = -1;

    char directory[MAX_SIZE];
    snprintf(directory, MAX_SIZE, SYSFS_PWM "/pwmchip%d/pwm%d", dev->chipid, dev->pin);
    struct stat dir;
    if (stat(directory, &dir) == 0 && S_ISDIR(dir.st_mode)) {
        syslog(LOG_NOTICE, "pwm: Pin already exported, continuing");
        dev->owner = 0; // Not Owner
    } else {
        char buffer[MAX_SIZE];
        snprintf(buffer, MAX_SIZE, "/sys/class/pwm/pwmchip%d/export", dev->chipid);
        int export_f = open(buffer, O_WRONLY);
        if (export_f == -1) {
            syslog(LOG_ERR, "pwm: Failed to open export for writing");
            free(dev);
            return NULL;
        }

        char out[MAX_SIZE];
        int size = snprintf(out, MAX_SIZE, "%d", dev->pin);
        if (write(export_f, out, size * sizeof(char)) == -1) {
            syslog(LOG_WARNING, "pwm: Failed to write to export! Potentially already enabled");
            close(export_f);
            free(dev);
            return NULL;
        }
        dev->owner = 1;
        mraa_pwm_period_us(dev, plat->pwm_default_period);
        close(export_f);
    }
    mraa_pwm_setup_duty_fp(dev);
    return dev;
}

mraa_result_t
mraa_pwm_write(mraa_pwm_context dev, float percentage)
{
    if (dev->period == -1) {
        if (mraa_pwm_read_period(dev) <= 0)
            return MRAA_ERROR_NO_DATA_AVAILABLE;
    }

    if (percentage >= 1.0f) {
        return mraa_pwm_write_duty(dev, dev->period);
    }
    return mraa_pwm_write_duty(dev, percentage * dev->period);
}

float
mraa_pwm_read(mraa_pwm_context dev)
{
    int period = mraa_pwm_read_period(dev);
    if (period > 0) {
        return (mraa_pwm_read_duty(dev) / (float) period);
    }
    return 0.0f;
}

mraa_result_t
mraa_pwm_period(mraa_pwm_context dev, float seconds)
{
    return mraa_pwm_period_ms(dev, seconds * 1000);
}

mraa_result_t
mraa_pwm_period_ms(mraa_pwm_context dev, int ms)
{
    return mraa_pwm_period_us(dev, ms * 1000);
}

mraa_result_t
mraa_pwm_period_us(mraa_pwm_context dev, int us)
{
    if (us < plat->pwm_min_period || us > plat->pwm_max_period) {
        syslog(LOG_ERR, "pwm: period value outside platform range");
        return MRAA_ERROR_INVALID_PARAMETER;
    }
    return mraa_pwm_write_period(dev, us * 1000);
}

mraa_result_t
mraa_pwm_pulsewidth(mraa_pwm_context dev, float seconds)
{
    return mraa_pwm_pulsewidth_ms(dev, seconds * 1000);
}

mraa_result_t
mraa_pwm_pulsewidth_ms(mraa_pwm_context dev, int ms)
{
    return mraa_pwm_pulsewidth_us(dev, ms * 1000);
}

mraa_result_t
mraa_pwm_pulsewidth_us(mraa_pwm_context dev, int us)
{
    return mraa_pwm_write_duty(dev, us * 1000);
}

mraa_result_t
mraa_pwm_enable(mraa_pwm_context dev, int enable)
{
    int status;
    if (enable != 0) {
        status = 1;
    } else {
        status = enable;
    }
    char bu[MAX_SIZE];
    snprintf(bu, MAX_SIZE, "/sys/class/pwm/pwmchip%d/pwm%d/enable", dev->chipid, dev->pin);

    int enable_f = open(bu, O_RDWR);

    if (enable_f == -1) {
        syslog(LOG_ERR, "pwm: Failed to open enable for writing");
        return MRAA_ERROR_INVALID_RESOURCE;
    }
    char out[2];
    int size = snprintf(out, sizeof(out), "%d", enable);
    if (write(enable_f, out, size * sizeof(char)) == -1) {
        syslog(LOG_ERR, "pwm: Failed to write to enable");
        close(enable_f);
        return MRAA_ERROR_INVALID_RESOURCE;
    }
    close(enable_f);
    return MRAA_SUCCESS;
}

mraa_result_t
mraa_pwm_unexport_force(mraa_pwm_context dev)
{
    char filepath[MAX_SIZE];
    snprintf(filepath, MAX_SIZE, "/sys/class/pwm/pwmchip%d/unexport", dev->chipid);

    int unexport_f = open(filepath, O_WRONLY);
    if (unexport_f == -1) {
        syslog(LOG_ERR, "pwm: Failed to open unexport for writing");
        return MRAA_ERROR_INVALID_RESOURCE;
    }

    char out[MAX_SIZE];
    int size = snprintf(out, MAX_SIZE, "%d", dev->pin);
    if (write(unexport_f, out, size * sizeof(char)) == -1) {
        syslog(LOG_ERR, "pwm: Failed to write to unexport");
        close(unexport_f);
        return MRAA_ERROR_INVALID_RESOURCE;
    }

    close(unexport_f);
    return MRAA_SUCCESS;
}

mraa_result_t
mraa_pwm_unexport(mraa_pwm_context dev)
{
    mraa_pwm_enable(dev, 0);
    if (dev->owner) {
        return mraa_pwm_unexport_force(dev);
    }
    return MRAA_ERROR_INVALID_RESOURCE;
}

mraa_result_t
mraa_pwm_close(mraa_pwm_context dev)
{
    mraa_pwm_unexport(dev);
    free(dev);
    return MRAA_SUCCESS;
}

mraa_result_t
mraa_pwm_owner(mraa_pwm_context dev, mraa_boolean_t owner_new)
{
    if (dev == NULL)
        return MRAA_ERROR_INVALID_RESOURCE;
    dev->owner = owner_new;
    return MRAA_SUCCESS;
}

mraa_result_t
mraa_pwm_config_ms(mraa_pwm_context dev, int ms, float ms_float)
{
    int old_dutycycle, old_period, status;
    old_dutycycle = mraa_pwm_read_duty(dev);
    old_period = mraa_pwm_read_period(dev);
    status = mraa_pwm_period_us(dev, ms * 1000);
    if (status != MRAA_SUCCESS) {
        mraa_pwm_write_duty(dev, old_dutycycle);
        return status;
    }
    status = mraa_pwm_write_duty(dev, 0);
    if (status != MRAA_SUCCESS) {
        return status;
    }
    status = mraa_pwm_pulsewidth_us(dev, ms_float * 1000);
    if (status != MRAA_SUCCESS) {
        mraa_pwm_write_duty(dev, old_dutycycle);
        mraa_pwm_write_period(dev, old_period);
        return status;
    }
    return MRAA_SUCCESS;
}

mraa_result_t
mraa_pwm_config_percent(mraa_pwm_context dev, int ms, float percentage)
{
    int old_dutycycle, old_period, status;
    old_dutycycle = mraa_pwm_read_duty(dev);
    old_period = mraa_pwm_read_period(dev);
    status = mraa_pwm_period_us(dev, ms * 1000);
    if (status != MRAA_SUCCESS) {
        mraa_pwm_write_duty(dev, old_dutycycle);
        return status;
    }
    status = mraa_pwm_write_duty(dev, 0);
    if (status != MRAA_SUCCESS) {
        return status;
    }
    status = mraa_pwm_pulsewidth_us(dev, (ms * 1000) * percentage);
    if (status != MRAA_SUCCESS) {
        mraa_pwm_write_duty(dev, old_dutycycle);
        mraa_pwm_write_period(dev, old_period);
        return status;
    }
    return MRAA_SUCCESS;
}