Read works now but uses git statusbusy waitgit status

char_dev.c

@@ -1,13 +1,4 @@
 
-static char device_buffer[1];
-static int major;
-static uint8_t buff_empty=1;
-static uint8_t buff_start;
-static uint8_t buff_end;
-
-
-static uint8_t buffer[BUFFER_SIZE];
-
 static uint8_t readBuffer(void){
     uint8_t ret;    
     if(buff_empty){
@@ -59,11 +50,12 @@ static ssize_t device_write(struct file *filp, const char __user *buff, size_t l
 	if(len!=1){
 		return -EINVAL;
 	}
-	ret = copy_from_user(device_buffer, buff, len);
+	ret = copy_from_user(pin_status, buff, len);
 	if( ret<0 ){
 		printk("<1>%s: Device write error!\n",MOD_NAME);
 		return 0;
 	}
+	n_written=0;
 	return len;
 }
 

ftdi_daemon.c

@@ -41,6 +41,7 @@ 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);
 		}
@@ -142,7 +143,7 @@ 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;
+	int val;
 	switch(state){
 		case CMD_PORT_NUM:
 			pin=c;
@@ -165,9 +166,14 @@ static int cmd_fsm(char c){
 					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,fd);
+					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;
 			}
 	}
@@ -176,7 +182,12 @@ static int cmd_fsm(char c){
 
 int main(void){
 	int ret=ftdi_chip_init();
-	fd=fopen("/dev/usb_gpio","rw");
+	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;
 	}

gpio_callbacks.c

@@ -1,13 +1,14 @@
 
 static int get_value(struct gpio_chip *gc, unsigned offset){
-	int ret;
-
 	DEBUG_OUT("<1>%s: GET_VALUE of pin%d ",MOD_NAME,offset);
 
-	ret=writeToBuffer(offset);
-	ret|=writeToBuffer(CMD_READ);
+	writeToBuffer(offset);
+	writeToBuffer(CMD_READ);
 
-	return -ret;
+	n_written=1;
+	while(n_written){};
+
+	return pin_status[0];
 }
 
 static void set_value(struct gpio_chip *chip, unsigned offset, int value){

usb_gpio.c

@@ -3,6 +3,16 @@
 static struct gpio_chip ft232_chip;
 static struct subprocess_info *sub_info;
 
+static char pin_status[1];
+static int major;
+static uint8_t buff_empty=1;
+static uint8_t buff_start;
+static uint8_t buff_end;
+
+static uint8_t buffer[BUFFER_SIZE];
+
+static volatile int n_written;
+
 #include "char_dev.c"
 #include "gpio_callbacks.c"