Will use message queues for IPC between the kernel and user-space helper

Makefile.helper

@@ -1,8 +1,8 @@
 
 OBJS = ftdi_daemon.o
 
-CC=gcc
+DEFINES := -DDEBUG
-CFLAGS = 
+CFLAGS = $(DEFINES)
 LDFLAGS = -lftdi
 
 usbgpiod: $(OBJS)

ftdi_daemon.c

@@ -10,8 +10,6 @@ volatile uint8_t main_loop=1;
 
 static int vendor=0x0403, device=0x6001;
 
-
-
 static int is_output(unsigned offset){
 	return !!((USB_GPIO_DDR)&(1<<offset));
 }
@@ -20,88 +18,158 @@ 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);
-		printf("%s: %s\n",MOD_NAME,ftdi_get_error_string(&ftdic));
+		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 ",MOD_NAME,offset);
+	DEBUG_OUT("%s: GET_VALUE of pin%d\n",MOD_NAME,offset);
+
 	if( !is_output(offset) ){
-		while( ftdic.readbuffer_remaining > 0 ){
+		if( ftdi_read_pins(&ftdic,&USB_GPIO_PIN) < 0){
-			if( ftdi_read_data(&ftdic,&USB_GPIO_PIN,1) < 0){
+			LOG("%s: Unable to read pin%d \n",MOD_NAME,offset);
-				printf("%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",MOD_NAME,offset,value);
+	DEBUG_OUT("%s: SET_VALUE of pin%d to %d\n",MOD_NAME,offset,value);
 
-	if( !is_output(offset) ){
+	if(value){
-		if(value && !is_high(offset)){
+		USB_GPIO_PORT |= (1<<offset);
-			if( ftdi_write_data(&ftdic,&USB_GPIO_PORT,1) < 0){
+	}else{
-				printf("%s: Unable to set pin%d to value %d\n",MOD_NAME,offset,value);
+		USB_GPIO_PORT &= ~(1<<offset);
-			}
+	}
-		}else if(!value && is_high(offset)){
+	if( ftdi_write_data(&ftdic,&USB_GPIO_PORT,1) < 0){
-			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);
-				printf("%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 ",MOD_NAME,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",MOD_NAME,offset,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
+	// Init FTDI lib
+	DEBUG_OUT("INIT libftdi\n");	
 	if( ftdi_init(&ftdic)<0 ){
-		printf("%s: Can't initialize FTDI-lib!\n",MOD_NAME);
+		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);
-		printf("%s: %s\n",MOD_NAME,ftdi_get_error_string(&ftdic));
+		LOG("%s: %s\n",MOD_NAME,ftdi_get_error_string(&ftdic));
         return ENXIO;
     }
-	// Put device into bitbang modes
-	if( ftdi_set_bitmode(&ftdic, 0x00, BITMODE_BITBANG)<0 ){
-        printf("%s: Can't enter FTDIs bitbang mode (%04x:%04x)!\n",MOD_NAME,vendor,device);
-		printf("%s: %s\n",MOD_NAME,ftdi_get_error_string(&ftdic));
-        return EIO;
-	}
 
 	//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 ){
-		printf("%s: Can't reset FTDI (%04x:%04x)!\n",MOD_NAME,vendor,device);
+		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 ret;
+	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:
+					ret = get_value((unsigned)pin);
+					DEBUG_OUT("Value of %d is %d\n", pin,ret);
+					fputc((char)ret,stdout);
+					return 0;
+			}
+	}
+	return 0;
 }
 
 int main(void){
@@ -111,7 +179,13 @@ int main(void){
 	}
 
 	for(;main_loop;){
-		//Sleep mostly
+		//kernel will write commands to the stdin
+		ret = fgetc(stdin);
+		if( ret!=EOF ){
+			cmd_fsm(ret);
+		}else{
+			//main_loop=0;
+		}
 	}
 
 	ftdi_chip_exit();

ftdi_daemon.h

@@ -1,19 +1,27 @@
 #ifndef _FTDL_DAEMON_H
 #define _FTDL_DAEMON_H
 
+#include <sys/msg.h>
 #include <ftdi.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <errno.h>
 
-#define MOD_NAME "usb_gpio"
+#include "common.h"
+
 
 #ifdef DEBUG
-	#define DEBUG_OUT(FMT,...) printk(FMT, ## __VA_ARGS__)
+	#define DEBUG_OUT(FMT,...) printf(FMT, ## __VA_ARGS__)
 #else
 	#define DEBUG_OUT(FMT,...) {}
 #endif
 
+#ifdef DEBUG
+	#define LOG(FMT,...) printf(FMT, ## __VA_ARGS__)
+#else
+	#define DEBUG_OUT(FMT,...) {} //FIXME: add a log-file
+#endif
+
 #define PIN_TX  0
 #define PIX_RX  1
 #define PIN_RTS 2

usb_gpio.c

@@ -1,6 +1,7 @@
 #include "usb_gpio.h"
 
 static struct gpio_chip ft232_chip;
+static struct subprocess_info *sub_info;
 
 #include "gpio_callbacks.c"
 
@@ -14,7 +15,7 @@ static void usb_gpio_exit(void) {
 static int usb_gpio_init(void) {
 	int ret;
 	// Prepare user space handler call
-	char *argv[] = { "/usr/bin/logger", "help!", NULL };
+	char *argv[] = { "/usr/bin/usb_gpio_ftdi_helper", NULL };
 	static char *envp[] = {
 		"HOME=/",
 		"TERM=linux",
@@ -45,7 +46,13 @@ static int usb_gpio_init(void) {
 	}
 	
 	//Call the user space handler
-	return call_usermodehelper( argv[0], argv, envp, UMH_WAIT_PROC );
+	sub_info = call_usermodehelper_setup( argv[0], argv, envp, GFP_ATOMIC );
+  	if (sub_info == NULL){
+		return -ENOMEM;
+	}
+
+	// the helper will run in the background until the module decides to kill it
+	return call_usermodehelper_exec( sub_info, UMH_NO_WAIT );
 }
 
 module_init(usb_gpio_init);

usb_gpio.h

@@ -9,12 +9,12 @@
 #include <linux/slab.h> /* kmalloc() */
 #include <linux/gpio.h>
 #include <linux/kmod.h>
-
+#include <linux/msg.h>
 
 #include "usb_gpio_util.h"
+#include "common.h"
 
 #define NUM_OF_GPIO 8
-#define MOD_NAME "usb_gpio"
 
 #ifndef CONFIG_GENERIC_GPIO
 #error This module needs generic gpio support (CONFIG_GENERIC_GPIO)