FTDI_kernel_space_gpio_driver/ftdi_daemon.c

#include "ftdi_daemon.h"

struct ftdi_context ftdic;

uint8_t USB_GPIO_DDR;
uint8_t USB_GPIO_PORT;
uint8_t USB_GPIO_PIN;

FILE* fd;

volatile uint8_t main_loop=1;

static int vendor=0x0403, device=0x6001;

static int is_output(unsigned offset){
	return !!((USB_GPIO_DDR)&(1<<offset));
}

static int is_high(unsigned offset){
	return !!((USB_GPIO_PORT)&(1<<offset));
}

/*! 
This will update the data direction according to the current
USB_GPIO_DDR value
*/
static int update_mode(void){
	if( ftdi_set_bitmode(&ftdic, USB_GPIO_DDR, BITMODE_BITBANG)<0 ){
        printf("%s: Can't enter FTDIs bitbang mode (%04x:%04x)!\n",MOD_NAME,vendor,device);
		LOG("%s: %s\n",MOD_NAME,ftdi_get_error_string(&ftdic));
        return -EIO;
	}
	return 0;
}

/*! 
If in output this will allways return 0
in input it will return the logic level of the pin
*/
static int get_value(unsigned offset){
	DEBUG_OUT("%s: GET_VALUE of pin%d\n",MOD_NAME,offset);

	if( !is_output(offset) ){
	
	if( ftdi_read_pins(&ftdic,&USB_GPIO_PIN) < 0){
			LOG("%s: Unable to read pin%d \n",MOD_NAME,offset);
		}
		return !!((USB_GPIO_PIN) & (1<<offset));
	}
	return 0;
}

/*!
If in input this will turn on/off the pullup
in output it will simply turn on/off the logic level of the pin
*/
static void set_value(unsigned offset, int value){
	DEBUG_OUT("%s: SET_VALUE of pin%d to %d\n",MOD_NAME,offset,value);

	if(value){
		USB_GPIO_PORT |= (1<<offset);
	}else{
		USB_GPIO_PORT &= ~(1<<offset);
	}
	if( ftdi_write_data(&ftdic,&USB_GPIO_PORT,1) < 0){
		LOG("%s: Unable to set pin%d to value %d\n",MOD_NAME,offset,value);
	}
}

/*!
This will set the pin as input. 
Warning: if the pin is HIGH at the moment you put the pin to input
the pull-up of that pin will be enabled
*/
static int set_in(unsigned offset){
	DEBUG_OUT("%s: SET_INPUT of pin%d\n",MOD_NAME,offset);

	USB_GPIO_DDR &= ~(1<<offset); 
	return update_mode();
}

/*
This will set the pin as output and drive its logic level according
to value.
*/
static int set_out(unsigned offset, int value){
	DEBUG_OUT("%s: SET_OUTPUT of pin%d to %d\n",MOD_NAME,offset,value);

	USB_GPIO_DDR |= (1<<offset); 
	set_value(offset,value);
	return update_mode();
}

static int ftdi_chip_init(){
	// Init FTDI lib
	DEBUG_OUT("INIT libftdi\n");	
	if( ftdi_init(&ftdic)<0 ){
		LOG("%s: Can't initialize FTDI-lib!\n",MOD_NAME);
		return ENOMEM;
	}

	// Open device
	DEBUG_OUT("Opening device (%04x:%04x) \n",vendor,device);	
	if(ftdi_usb_open(&ftdic, vendor, device)<0) {
        printf("%s: Can't open FTDI chip (%04x:%04x)!\n",MOD_NAME,vendor,device);
		LOG("%s: %s\n",MOD_NAME,ftdi_get_error_string(&ftdic));
        return ENXIO;
    }

	//All pins input
	USB_GPIO_DDR  = 0x00;
	//No port set
	USB_GPIO_PORT = 0x00;

	// Put device into bitbang mode
	DEBUG_OUT("Putting device (%04x:%04x) into bitbang mode\n",vendor,device);	
	if( ftdi_set_bitmode(&ftdic, 0x00, BITMODE_BITBANG)<0 ){
        printf("%s: Can't enter FTDIs bitbang mode (%04x:%04x)!\n",MOD_NAME,vendor,device);
		LOG("%s: %s\n",MOD_NAME,ftdi_get_error_string(&ftdic));
        return EIO;
	}
	// Set all pins low
	if( ftdi_write_data(&ftdic,&USB_GPIO_PORT,1) < 0){
		LOG("%s: Unable to set pins to low\n",MOD_NAME);
		return EIO;
	}	
	return 0;
}

static void ftdi_chip_exit(){
	if( ftdi_disable_bitbang(&ftdic)<0 ){
		LOG("%s: Can't reset FTDI (%04x:%04x)!\n",MOD_NAME,vendor,device);
	}
	if( ftdi_usb_close(&ftdic) < 0){
		LOG("%s: Unable to close FTDI-Device!\n",MOD_NAME);
		LOG("%s: %s\n",MOD_NAME,ftdi_get_error_string(&ftdic));
	}
	ftdi_deinit(&ftdic);
}

enum cmd_states {CMD_PORT_NUM, CMD_CMD};

static int cmd_fsm(char c){
	static int state = CMD_PORT_NUM;
	static char pin = 0;
	int val;
	switch(state){
		case CMD_PORT_NUM:
			pin=c;
			state=CMD_CMD;
			break;
		case CMD_CMD:
			state = CMD_PORT_NUM;
			// Pin commands
			switch(c){
				case CMD_IN:
					return set_in((unsigned)pin);
				case CMD_OUTH:
					return set_out((unsigned)pin,1);
				case CMD_OUTL:
					return set_out((unsigned)pin,0);
				case CMD_H:
					set_value((unsigned)pin,1);
					return 0;
				case CMD_L:
					set_value((unsigned)pin,0);
					return 0;
				case CMD_READ:
					val = get_value((unsigned)pin);
					DEBUG_OUT("Value of %d is %d\n", pin,val);
					errno=0;
					fputc((char)val,fd);
					if( errno ){
						LOG("%s: Error writing to device ernno=%d\n",MOD_NAME,errno );
					}
					fflush(fd);
					return 0;
			}
	}
	return 0;
}

int main(void){
	int ret=ftdi_chip_init();
	errno=0;
	fd=fopen("/dev/usb_gpio","r+");
	if(fd==(void*)0){
		LOG("%s: Could not open device errno=%d\n",MOD_NAME,errno );
		return errno;
	}
	if(ret!=0){
		return ret;
	}

	for(;main_loop;){
		//kernel will write commands to the device file
		ret = fgetc(fd);
		if( ret!=EOF ){
			DEBUG_OUT("read %02x\n",ret);
			cmd_fsm(ret);
		}else{
			//main_loop=0;
		}
	}

	ftdi_chip_exit();
	return 0;
}