/*********************************************************************************
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* Copyright: (C) 2021 LingYun IoT System Studio
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* All rights reserved.
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*
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* Filename: pwm.c
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* Description: This file is used to control PWM buzzer/Led
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*
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* Pin connection:
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* PWM Module Raspberry Pi Board
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* VCC <-----> 5V
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* buzzer <-----> #Pin32(BCM GPIO12)
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* Led <-----> #Pin33(BCM GPIO13)
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* GND <-----> GND
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*
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* /boot/config.txt:
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*
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* dtoverlay=pwm,pin=12,func=4 (Buzzer)
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* dtoverlay=pwm,pin=13,func=4 (Led)
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*
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********************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <dirent.h>
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#include <string.h>
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#include <time.h>
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#include <errno.h>
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#include <signal.h>
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#include <getopt.h>
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#include <libgen.h>
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#include <gpiod.h>
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#define PWMCHIP_PATH "/sys/class/pwm/pwmchip0"
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#define ENABLE 1
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#define DISABLE 0
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int init_pwm(int channel, int freq, int duty);
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int turn_pwm(int channel, int status);
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int term_pwm(int channel);
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static inline void msleep(unsigned long ms);
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static inline void banner(const char *progname)
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{
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printf("%s program Version v1.0.0\n", progname);
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printf("Copyright (C) 2023 LingYun IoT System Studio.\n");
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}
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static void program_usage(const char *progname)
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{
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printf("Usage: %s [OPTION]...\n", progname);
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printf(" This is pwm control program. \n");
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printf(" -c[channel ] Specify PWM channel, such as 0\n");
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printf(" -f[freq ] Specify PWM frequency, default 2500(Hz)\n");
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printf(" -d[duty ] Specify PWM duty, default 50(50%%)\n");
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printf(" -s[status ] Specify PWM status: 1->on(default), 0->off\n");
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printf(" -h[help ] Display this help information\n");
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printf(" -v[version ] Display the program version\n");
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printf("\n");
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printf("Example buzzer : %s -c 0 -f 2750 -d 50 -s 1\n", progname);
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printf("Example Led : %s -c 1 -f 100 -d 50 -s 1\n", progname);
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printf("Example disable: %s -c 0 -s 0\n", progname);
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printf("\n");
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banner(progname);
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return;
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}
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int main(int argc, char **argv)
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{
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int rv;
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char *progname=NULL;
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int channel = -1;
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int freq = 2500;
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int duty = 50;
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int status = ENABLE;
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struct option long_options[] = {
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{"channel", required_argument, NULL, 'c'},
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{"freq", required_argument, NULL, 'f'},
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{"duty", required_argument, NULL, 'd'},
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{"status", required_argument, NULL, 's'},
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{"version", no_argument, NULL, 'v'},
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{"help", no_argument, NULL, 'h'},
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{NULL, 0, NULL, 0}
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};
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progname = basename(argv[0]);
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/* Parser the command line parameters */
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while ((rv = getopt_long(argc, argv, "c:f:d:s:vh", long_options, NULL)) != -1)
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{
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switch (rv)
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{
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case 'c': /* Set pwm channel, such as 0,1 */
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channel = atoi(optarg);
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break;
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case 'f': /* Set pwm frequency */
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freq = atoi(optarg);
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break;
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case 'd': /* Set pwm duty cycle */
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duty = atoi(optarg);
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break;
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case 's': /* Set pwm status, 0 for disable and 1 for enable */
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status = atoi(optarg);
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break;
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case 'v': /* Get software version */
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banner(progname);
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return EXIT_SUCCESS;
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case 'h': /* Get help information */
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program_usage(progname);
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return 0;
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default:
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break;
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}
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}
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if(channel < 0 )
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{
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program_usage(progname);
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return 0;
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}
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if( status )
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{
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if( (rv=init_pwm(channel, freq, duty)) < 0 )
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{
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printf("initial PWM failure, rv=%d\n", rv);
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return 1;
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}
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turn_pwm(channel, ENABLE);
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}
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else
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{
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term_pwm(channel);
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}
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return 0;
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}
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/* check PWM $channel export or not */
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int check_pwm(int channel)
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{
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char path[256];
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/* check /sys/class/pwm/pwmchip0/pwmN exist or not */
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snprintf(path, sizeof(path), "%s/pwm%d", PWMCHIP_PATH, channel);
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return access(path, F_OK) ? 0 : 1;
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}
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/* export($export=1)/unexport($export=0) PWM $channel */
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int export_pwm(int channel, int export)
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{
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int fd;
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char buf[32];
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char path[256];
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if( export && check_pwm(channel) )
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return 0; /* export already when export */
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else if( !export && !check_pwm(channel) )
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return 0; /* unexport already when unexport */
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/* export PWM channel by echo N > /sys/class/pwm/pwmchip0/export */
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snprintf(path, sizeof(path), "%s/%s", PWMCHIP_PATH, export?"export":"unexport");
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if( (fd=open(path, O_WRONLY)) < 0 )
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{
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printf("open '%s' failed: %s\n", path, strerror(errno));
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return -3;
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}
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snprintf(buf, sizeof(buf), "%d", channel);
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write(fd, buf, strlen(buf));
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msleep(100);
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if( export && check_pwm(channel) )
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return 0; /* export already when export */
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else if( !export && !check_pwm(channel) )
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return 0; /* unexport already when unexport */
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return -4;
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}
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/* configure PWM $channel */
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int config_pwm(int channel, int freq, int duty)
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{
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int fd;
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char buf[32];
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char path[256];
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int period;
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int duty_cycle;
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if( !check_pwm(channel) )
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return -2;
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/* open PWM period file and write period in ns */
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snprintf(path, sizeof(path), "%s/pwm%d/period", PWMCHIP_PATH, channel);
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if( (fd=open(path, O_WRONLY)) < 0 )
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{
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printf("open '%s' failed: %s\n", path, strerror(errno));
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return -3;
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}
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period = 1000000000/freq;
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snprintf(buf, sizeof(buf), "%d", period);
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write(fd, buf, strlen(buf));
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/* open PWM duty_cycle file and write duty */
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snprintf(path, sizeof(path), "%s/pwm%d/duty_cycle", PWMCHIP_PATH, channel);
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if( (fd=open(path, O_WRONLY)) < 0 )
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{
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printf("open '%s' failed: %s\n", path, strerror(errno));
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return -3;
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}
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duty_cycle = (period*duty) / 100;
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snprintf(buf, sizeof(buf), "%d", duty_cycle);
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write(fd, buf, strlen(buf));
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return 0;
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}
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int init_pwm(int channel, int freq, int duty)
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{
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int rv;
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char buf[32];
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char path[256];
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if( (rv=export_pwm(channel, 1)) )
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{
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printf("export PWM channel[%d] failed, rv=%d\n", channel, rv);
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return rv;
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}
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if( (rv=config_pwm(channel, freq, duty)) )
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{
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printf("config PWM channel[%d] failed, rv=%d\n", channel, rv);
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return rv;
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}
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printf("config pwm%d with freq[%d] duty[%d] okay\n", channel, freq, duty);
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return 0;
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}
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int turn_pwm(int channel, int status)
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{
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int fd;
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char buf[32];
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char path[256];
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if( !check_pwm(channel) )
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return -1;
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/* open PWM enable file and enable(1)/disable(0) it */
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snprintf(path, sizeof(path), "%s/pwm%d/enable", PWMCHIP_PATH, channel);
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if( (fd=open(path, O_WRONLY)) < 0 )
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{
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printf("open '%s' failed: %s\n", path, strerror(errno));
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return -3;
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}
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snprintf(buf, sizeof(buf), "%d", status?1:0);
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write(fd, buf, strlen(buf));
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printf("pwm[%d] %s\n", channel, status?"enable":"disable");
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return 0;
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}
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int term_pwm(int channel)
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{
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if( !check_pwm(channel) )
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return 0;
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turn_pwm(channel, DISABLE);
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export_pwm(channel, 0);
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return 0;
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}
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static inline void msleep(unsigned long ms)
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{
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struct timespec cSleep;
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unsigned long ulTmp;
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cSleep.tv_sec = ms / 1000;
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if (cSleep.tv_sec == 0)
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{
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ulTmp = ms * 10000;
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cSleep.tv_nsec = ulTmp * 100;
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}
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else
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{
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cSleep.tv_nsec = 0;
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}
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nanosleep(&cSleep, 0);
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return ;
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}
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