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Code Issues Releases Activity

Sets up softpwm struct and thread

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This commit is contained in:
Brady L. Hurlburt
2016-04-10 16:45:13 -04:00
parent 9ac22c32cd
commit 9645d2aae3
1 changed files with 64 additions and 93 deletions
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157
source/c_softpwm.c
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@ -35,8 +35,11 @@ SOFTWARE.
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <pthread.h>
#include <time.h>
#include "c_pwm.h"
#include "common.h"
#include "event_gpio.h"
#define KEYLEN 7
@ -46,23 +49,19 @@ SOFTWARE.
int pwm_initialized = 0;
// pwm exports
struct pwm_exp
struct softpwm
{
char key[KEYLEN+1]; /* leave room for terminating NUL byte */
int period_fd;
int duty_fd;
int polarity_fd;
int enable_fd;
int enable;
unsigned long duty;
unsigned long period_ns;
struct pwm_exp *next;
unsigned long on_ns;
unsigned long off_ns;
pthread_t thread;
struct softpwm *next;
};
struct pwm_exp *exported_pwms = NULL;
struct softpwm *exported_pwms = NULL;
struct pwm_exp *lookup_exported_pwm(const char *key)
struct softpwm *lookup_exported_pwm(const char *key)
{
struct pwm_exp *pwm = exported_pwms;
struct softpwm *pwm = exported_pwms;
while (pwm != NULL)
{
@ -75,35 +74,11 @@ struct pwm_exp *lookup_exported_pwm(const char *key)
return NULL; /* standard for pointers */
}
int initialize_pwm(void)
{
if (!pwm_initialized) {
int fd, len;
char str_gpio[2];
// Per https://github.com/NextThingCo/CHIP-linux/pull/4
// we need to export 0 here to enable pwm0
int gpio = 0;
if ((fd = open("/sys/class/pwm/pwmchip0/export", O_WRONLY)) < 0)
{
return -1;
}
len = snprintf(str_gpio, sizeof(str_gpio), "%d", gpio);
write(fd, str_gpio, len);
close(fd);
pwm_initialized = 1;
return 1;
}
return 0;
}
int softpwm_set_frequency(const char *key, float freq) {
int len;
char buffer[20];
unsigned long period_ns;
struct pwm_exp *pwm;
struct softpwm *pwm;
if (freq <= 0.0)
return -1;
@ -129,7 +104,7 @@ int softpwm_set_frequency(const char *key, float freq) {
int softpwm_set_polarity(const char *key, int polarity) {
int len;
char buffer[9]; /* allow room for trailing NUL byte */
struct pwm_exp *pwm;
struct softpwm *pwm;
pwm = lookup_exported_pwm(key);
@ -156,7 +131,7 @@ int softpwm_set_polarity(const char *key, int polarity) {
int softpwm_set_duty_cycle(const char *key, float duty) {
int len;
char buffer[20];
struct pwm_exp *pwm;
struct softpwm *pwm;
if (duty < 0.0 || duty > 100.0)
return -1;
@ -179,7 +154,7 @@ int softpwm_set_enable(const char *key, int enable)
{
int len;
char buffer[20];
struct pwm_exp *pwm;
struct softpwm *pwm;
if (enable != 0 || enable != 1)
return -1;
@ -198,66 +173,65 @@ int softpwm_set_enable(const char *key, int enable)
return 0;
}
void* softpwm_toggle(void *key)
{
struct softpwm *pwm;
unsigned int gpio;
struct timespec tim;
unsigned int sec;
get_gpio_number(key, &gpio);
pwm = lookup_exported_pwm((char*)key);
while (1) {
sec = (unsigned int)(pwm->on_ns/1e9);
tim.tv_sec = sec;
tim.tv_nsec = pwm->on_ns - (sec*1e9);
gpio_set_value(gpio, HIGH);
nanosleep(&tim, NULL);
sec = (unsigned int)(pwm->off_ns/1e9);
tim.tv_sec = sec;
tim.tv_nsec = pwm->off_ns - (sec*1e9);
gpio_set_value(gpio, LOW);
nanosleep(&tim, NULL);
}
}
int softpwm_start(const char *key, float duty, float freq, int polarity)
{
char pwm_base_path[45];
char period_path[50];
char duty_path[50];
char enable_path[50];
char polarity_path[55];
int period_fd, duty_fd, polarity_fd, enable_fd;
struct pwm_exp *new_pwm, *pwm;
struct softpwm *new_pwm, *pwm;
pthread_t *new_thread;
unsigned int gpio;
unsigned long period_ns;
unsigned long on_ns;
int ret;
if(!pwm_initialized) {
initialize_pwm();
}
//setup the pwm base path, the chip only has one pwm
snprintf(pwm_base_path, sizeof(pwm_base_path), "/sys/class/pwm/pwmchip0/%d", "pwm0");
//create the path for the period and duty
snprintf(enable_path, sizeof(enable_path), "%s/enable", pwm_base_path);
snprintf(period_path, sizeof(period_path), "%s/period", pwm_base_path);
snprintf(duty_path, sizeof(duty_path), "%s/duty_cycle", pwm_base_path);
snprintf(polarity_path, sizeof(polarity_path), "%s/polarity", pwm_base_path);
//add period and duty fd to pwm list
if ((enable_fd = open(enable_path, O_RDWR)) < 0)
return -1;
if ((period_fd = open(period_path, O_RDWR)) < 0) {
close(enable_fd);
return -1;
}
if ((duty_fd = open(duty_path, O_RDWR)) < 0) {
//error, close already opened period_fd.
close(enable_fd);
close(period_fd);
return -1;
}
if ((polarity_fd = open(polarity_path, O_RDWR)) < 0) {
//error, close already opened period_fd and duty_fd.
close(enable_fd);
close(period_fd);
close(duty_fd);
return -1;
}
get_gpio_number(key, &gpio);
gpio_export(gpio);
gpio_set_direction(gpio, OUTPUT);
// add to list
new_pwm = malloc(sizeof(struct pwm_exp));
new_pwm = malloc(sizeof(struct softpwm));
if (new_pwm == 0) {
return -1; // out of memory
}
// calculate period and on time from freq
period_ns = (unsigned long)(1e9 / freq);
on_ns = (unsigned long)(period_ns * (duty/100));
// create thread for pwm
ret = pthread_create(new_thread, NULL, softpwm_toggle, (void *)key);
if (ret){
printf("ERROR; return code from pthread_create() is %d\n", ret);
exit(-1);
}
strncpy(new_pwm->key, key, KEYLEN); /* can leave string unterminated */
new_pwm->key[KEYLEN] = '\0'; /* terminate string */
new_pwm->period_fd = period_fd;
new_pwm->duty_fd = duty_fd;
new_pwm->polarity_fd = polarity_fd;
new_pwm->enable_fd = enable_fd;
new_pwm->on_ns = on_ns;
new_pwm->off_ns = period_ns - on_ns;
new_pwm->thread = *new_thread;
new_pwm->next = NULL;
if (exported_pwms == NULL)
@ -272,17 +246,14 @@ int softpwm_start(const char *key, float duty, float freq, int polarity)
pwm->next = new_pwm;
}
softpwm_set_frequency(key, freq);
softpwm_set_polarity(key, polarity);
softpwm_set_enable(key, 1);
softpwm_set_duty_cycle(key, duty);
return 1;
}
int softpwm_disable(const char *key)
{
struct pwm_exp *pwm, *temp, *prev_pwm = NULL;
struct softpwm *pwm, *temp, *prev_pwm = NULL;
char fragment[18];
int fd, len;