/*
 * This program enables the user to fiddle with GPIO pins.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/mman.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>

// See page 155 of SPRUH73H (AM335X) October 2011
// Base address of GPIO0
#define AM335X_GPIO0_BASE		    0x44E07000
// Base address of GPIO1
#define AM335X_GPIO1_BASE		    0x4804C000
// Base address of GPIO2
#define AM335X_GPIO2_BASE		    0x481AC000
// Base address of GPIO3
#define AM335X_GPIO3_BASE		    0x481AE000
// GPIO register size
#define AM335X_GPIO_SIZE		    0x1000
// This register is used to enable the pins output capabilities.
#define AM335X_GPIO_OE		    	0x134
//This register is used to register the data that is read from the GPIO pins.
#define AM335X_GPIO_DATAIN			0x138
// This register is used for setting the value of the GPIO output pins
#define AM335X_GPIO_DATAOUT			0x13C
// This register is used to register the data that is read from the GPIO pins.
#define AM335X_GPIO_SETDATAOUT		0x190
// This register is used for setting the value of the GPIO output pins
#define AM335X_GPIO_CLEARDATAOUT	0x194

#define MAX_NO_OF_GPIO_BANKS        (4)
#define GPIO_MODULE0                (0)
#define GPIO_MODULE1                (1)
#define GPIO_MODULE2                (2)
#define GPIO_MODULE3                (3)

#define USR0_LED_D1 (4)
#define USR1_LED_D2 (5)
#define USR2_LED_D3 (7)
#define USR3_LED_D4 (6)


#define USR0_KEY_SW1 (3)
#define USR1_KEY_SW2 (2)
#define USR2_KEY_SW3 (30)
#define USR3_KEY_SW4 (5)

#define OUT          (0)
#define IN           (1)

uint32_t gpio_base[] = {
	AM335X_GPIO0_BASE,
	AM335X_GPIO1_BASE,
	AM335X_GPIO2_BASE,
	AM335X_GPIO3_BASE,
	0/*NULL*/
};

void *gpio_addr[MAX_NO_OF_GPIO_BANKS] = { NULL };
unsigned int *gpio_oe_addr = NULL;
unsigned int *gpio_dataout_addr = NULL;
unsigned int *gpio_datain_addr = NULL;
unsigned int *gpio_setdataout_addr = NULL;
unsigned int *gpio_cleardataout_addr = NULL;

void *pinmux_addr = NULL;
unsigned int *used_pinmux_addr = NULL;

int  mem_fd;
int gpio_module = -1;

void gpio_set(int gpio_module_no, int pin)
{
	unsigned int reg;
	gpio_dataout_addr = gpio_addr[gpio_module_no] + AM335X_GPIO_DATAOUT;
	reg = *gpio_dataout_addr;
	reg = reg | (1 << pin);
	*gpio_dataout_addr = reg;
	printf("gpio_set: pin value = %d\treg value = 0x%X\n",pin, reg);
}

void gpio_reset(int gpio_module_no, int pin)
{
	unsigned int reg;
	gpio_dataout_addr = gpio_addr[gpio_module_no] + AM335X_GPIO_DATAOUT;
	reg = *gpio_dataout_addr;
	reg = reg & ~(1 << pin);
	*gpio_dataout_addr = reg;
	//printf("gpio_reset: pin value = %d\treg value = 0x%X\n",pin, reg);	
}

int gpio_read(int gpio_module_no, int direction, int pin)
{
	int pin_value = 0;
	unsigned int reg;
	if (direction == 0) {
		gpio_dataout_addr = gpio_addr[gpio_module_no] + AM335X_GPIO_DATAOUT;
		reg = *gpio_dataout_addr;
		if (reg & (1 << pin)) {
			pin_value = 1;
		}
	}
	else if (direction == 1) {
		gpio_datain_addr = gpio_addr[gpio_module_no] + AM335X_GPIO_DATAIN;
		reg = *gpio_datain_addr;
		if (reg & (1 << pin)) {
			pin_value = 1;
		}
	}
	else{
		pin_value = -1;
	}
	if (pin_value == 1)
		printf("gpio_read: pin value = %d\n",pin_value);
	return pin_value;
}

void gpio_set_direction(int gpio_module_no, int direction, int pin)
{
	unsigned int reg;
	gpio_oe_addr = gpio_addr[gpio_module_no] + AM335X_GPIO_OE;
	reg = *gpio_oe_addr;
	printf("gpio_set_direction: reg initial = 0x%X\n",reg);
	if (direction == 0) {
		reg = reg & ~(1 << pin);
		*gpio_oe_addr = reg;
	} else {
		reg = reg | (1 << pin);
		*gpio_oe_addr = reg;
	}
	printf("gpio_set_direction: reg after setting dir = 0x%X\n",reg);
}

/*
 * Set up a memory regions to access GPIO
 */
void setup_io()
{
	int i = 0;
	/* open /dev/mem */
	if ((mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) {
		printf("main: can't open /dev/mem \n");
		exit(-1);
	}
	printf("main: mem_fd = %d\n",mem_fd);
	/* mmap GPIO Bank1 */
	gpio_addr[GPIO_MODULE0]
		= mmap(
				NULL,                   //Any adddress in our space will do
				AM335X_GPIO_SIZE,       //Map length
				PROT_READ|PROT_WRITE,   // Enable reading & writting to mapped memory
				MAP_SHARED,             //Shared with other processes
				mem_fd,                 //File to map
				gpio_base[GPIO_MODULE0] //Offset to GPIO peripheral
		      );
	/* mmap GPIO Bank2*/
	gpio_addr[GPIO_MODULE1]
		= mmap(
				NULL,                   //Any adddress in our space will do
				AM335X_GPIO_SIZE,       //Map length
				PROT_READ|PROT_WRITE,   // Enable reading & writting to mapped memory
				MAP_SHARED,             //Shared with other processes
				mem_fd,                 //File to map
				gpio_base[GPIO_MODULE1] //Offset to GPIO peripheral
		      );
	/* mmap GPIO Bank3*/
	gpio_addr[GPIO_MODULE2]
		= mmap(
				NULL,                   //Any adddress in our space will do
				AM335X_GPIO_SIZE,       //Map length
				PROT_READ|PROT_WRITE,   // Enable reading & writting to mapped memory
				MAP_SHARED,             //Shared with other processes
				mem_fd,                 //File to map
				gpio_base[GPIO_MODULE2] //Offset to GPIO peripheral
		      );
	/* mmap GPIO Bank4*/
	gpio_addr[GPIO_MODULE3]
		= mmap(
				NULL,                   //Any adddress in our space will do
				AM335X_GPIO_SIZE,       //Map length
				PROT_READ|PROT_WRITE,   // Enable reading & writting to mapped memory
				MAP_SHARED,             //Shared with other processes
				mem_fd,                 //File to map
				gpio_base[GPIO_MODULE3] //Offset to GPIO peripheral
		      );				
	//printf("main: gpio_base[%d] = 0x%X\n", gpio_module, gpio_base[gpio_module]); 
	close(mem_fd); //No need to keep mem_fd open after mmap
	for ( i = 0; i < MAX_NO_OF_GPIO_BANKS; i++ ) {
		if (gpio_addr[i] == MAP_FAILED) {
			printf("mmap error %d\n", (int)gpio_addr[i]);//errno also set!
			exit(-1);
		}
	}    
} // setup_io

int set_trigger (void) {
	FILE *fp = NULL;
	/* create a variable to store what we are sending */
	char set_value[20]; 

	/* Using sysfs we need to write "none" to /sys/class/leds/am335x:EVM_SK:heartbeat
	   /trigger */  
	if ((fp = fopen("/sys/class/leds/am335x:EVM_SK:heartbeat/trigger",
					"ab")) == NULL) {
		printf("Cannot open trigger file.\n");
		exit(1);
	}
	/* Set pointer to begining of the file */
	rewind(fp);
	/* Write our value of "heartbeat" to the file */
	strcpy(set_value,"none");
	fwrite(&set_value, sizeof(char), 4, fp);
	fclose(fp);

	/* Using sysfs we need to write "none" to /sys/class/leds/am335x:EVM_SK:mmc0
	   /trigger */  
	if ((fp = fopen("/sys/class/leds/am335x:EVM_SK:mmc0/trigger",
					"ab")) == NULL) {
		printf("Cannot open trigger file.\n");
		exit(1);
	}
	/* Set pointer to begining of the file */
	rewind(fp);
	/* Write our value of "heartbeat" to the file */
	strcpy(set_value,"none");
	fwrite(&set_value, sizeof(char), 4, fp);
	fclose(fp);

	return 0;
}

int main (int argc, char *argv[])
{
	int i = 0;
	set_trigger();  
	setup_io();

	/* Unbind LEDs D3 & D4 */

	/* Set LEDs as output */
	gpio_set_direction(GPIO_MODULE1, USR0_LED_D1, OUT);
	gpio_set_direction(GPIO_MODULE1, USR1_LED_D2, OUT);
	gpio_set_direction(GPIO_MODULE1, USR2_LED_D3, OUT);
	gpio_set_direction(GPIO_MODULE1, USR3_LED_D4, OUT);

	printf("main: LEDs set as outputs successfully\n");

	/* Set Keys as inputs */
	gpio_set_direction(GPIO_MODULE2, USR0_KEY_SW1, IN);
	gpio_set_direction(GPIO_MODULE2, USR1_KEY_SW2, IN);	
	gpio_set_direction(GPIO_MODULE0, USR2_KEY_SW3, IN);	
	gpio_set_direction(GPIO_MODULE2, USR3_KEY_SW4, IN);				

	printf("main: Keys set as inputs successfully\n");
	while (1) {
		if (1 == gpio_read(GPIO_MODULE2, IN, USR0_KEY_SW1) ) 
			gpio_set(GPIO_MODULE1, USR0_LED_D1);
		else gpio_reset(GPIO_MODULE1, USR0_LED_D1);

		if (1 == gpio_read(GPIO_MODULE2, IN, USR1_KEY_SW2) )
			gpio_set(GPIO_MODULE1, USR1_LED_D2);
		else gpio_reset(GPIO_MODULE1, USR1_LED_D2);

		if (1 == gpio_read(GPIO_MODULE0, IN, USR2_KEY_SW3) )
		{	        gpio_set(GPIO_MODULE1, USR2_LED_D3);printf("Hello Boss!!\n");}
		else gpio_reset(GPIO_MODULE1, USR2_LED_D3);

		if (1 == gpio_read(GPIO_MODULE2, IN, USR3_KEY_SW4) )
			gpio_set(GPIO_MODULE1, USR3_LED_D4);
		else gpio_reset(GPIO_MODULE1, USR3_LED_D4);
	}
	for ( i = 0; i < MAX_NO_OF_GPIO_BANKS; i++ ) {
		munmap((void *)gpio_addr[i], AM335X_GPIO_SIZE);
	}
	return 0;
}