/*
 *  bbb-gpmc-test
 *
 *  Copyright (C) 2014  Timothy Pearson <kb9vqf@pearsoncomputing.net> (Beaglebone Black)
 *
 *  Permission to use, copy, modify, and/or distribute this software for any
 *  purpose with or without fee is hereby granted, provided that the above
 *  copyright notice and this permission notice appear in all copies.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

#include <sys/time.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>


/** BEGIN: Low-Level I/O Implementation **/

// Beaglebone Black GPMC driver

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>

#define MEMORY_SPACE_ADDRESS_BITS 16

#define GPMC_BASE 0x50000000
#define GPMC_REGLEN 0x10000000

#define GPMC_CHIPSELECTCONFIGDISPLACEMENT (0x30 / 4)

#define GPMC_CONFIG (0x50 / 4)
#define GPMC_CONFIG1 (0x60 / 4)
#define GPMC_CONFIG2 (0x64 / 4)
#define GPMC_CONFIG3 (0x68 / 4)
#define GPMC_CONFIG4 (0x6c / 4)
#define GPMC_CONFIG5 (0x70 / 4)
#define GPMC_CONFIG6 (0x74 / 4)
#define GPMC_CONFIG7 (0x78 / 4)

#define MEMORY_SIZE (1 << MEMORY_SPACE_ADDRESS_BITS)

int mem_fd = 0;
int gpmc_mem_fd = 0;
char *gpio_mem, *gpio_map, *gpmc_map;

// I/O access
static volatile unsigned int *gpio = NULL;
static volatile unsigned char *gpio_char = NULL;
static volatile unsigned int *gpmc = NULL;

static void gpmc_mapregisters()
{
	/* open /dev/mem */
	if ((gpmc_mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) {
		printf("can't open /dev/mem \n");
		exit (-1);
	}

	/* mmap GPMC */
	gpmc_map = (char *)mmap(
		0,
		GPMC_REGLEN,
		PROT_READ|PROT_WRITE,
		MAP_SHARED,
		gpmc_mem_fd,
		GPMC_BASE
	);

	if (gpmc_map == MAP_FAILED) {
		printf("mmap error %d\n", (int)gpmc_map);
		exit (-1);
	}

	// Always use volatile pointer!
	gpmc = (volatile unsigned *)gpmc_map;
}

static void gpmc_unmapregisters()
{
	munmap((void*) gpmc, GPMC_REGLEN);
	if (gpmc_mem_fd != -1) {
		close(gpmc_mem_fd);
	}
}

static void gpmc_setup(void)
{
	// WARNING: The GPMC runs at the L3 clock frequency!
	// It is not well documented, but that frequency seems to be 200MHz on the AM335x series of chips

	gpmc_mapregisters();

	if (gpmc != NULL) {
		int chipselect = 0;
		int displacement = GPMC_CHIPSELECTCONFIGDISPLACEMENT * chipselect;

		// disable before playing with the registers
		*(gpmc + displacement + GPMC_CONFIG7) = 0x00000000;

		*(gpmc + displacement + GPMC_CONFIG)  = 0x00000000; // Unlimited address space
		*(gpmc + displacement + GPMC_CONFIG1) = 0x00000000; // No burst, async, 8-bit, non multiplexed

// 		// 200MHz compatible SRAM device
// 		*(gpmc + displacement + GPMC_CONFIG2) = 0x00000800; // Assert CS on fclk 0, deassert CS on fclk 8
// 		*(gpmc + displacement + GPMC_CONFIG3) = 0x00000200; // Assert ADV on fclk0, deassert ADV on fclk2
// 		*(gpmc + displacement + GPMC_CONFIG4) = 0x06020802; // Assert WE on fclk2, deassert WE on fclk6, assert OE on fclk2, deassert OE on fclk8
// 		*(gpmc + displacement + GPMC_CONFIG5) = 0x00060808; // Data valid on fclk 6, cycle time 8 fclks

// 		// 100MHz compatible SRAM device
// 		*(gpmc + displacement + GPMC_CONFIG2) = 0x00001000; // Assert CS on fclk0, deassert CS on fclk16
// 		*(gpmc + displacement + GPMC_CONFIG3) = 0x00000400; // Assert ADV on fclk 0, deassert ADV on fclk 4
// 		*(gpmc + displacement + GPMC_CONFIG4) = 0x0c041004; // Assert WE on fclk4, deassert WE on fclk12, assert OE on fclk4, deassert OE on fclk16
// 		*(gpmc + displacement + GPMC_CONFIG5) = 0x000c1010; // Data valid on fclk 12, cycle time 16 fclks

		// 50MHz compatible SRAM device
		*(gpmc + displacement + GPMC_CONFIG2) = 0x00001f00; // Assert CS on fclk0, deassert CS on fclk31
		*(gpmc + displacement + GPMC_CONFIG3) = 0x00000400; // Assert ADV on fclk 0, deassert ADV on fclk 4
		*(gpmc + displacement + GPMC_CONFIG4) = 0x1f041f04; // Assert WE on fclk4, deassert WE on fclk31, assert OE on fclk4, deassert OE on fclk31
		*(gpmc + displacement + GPMC_CONFIG5) = 0x00101f1f; // Data valid on fclk 16, cycle time 31 fclks

		*(gpmc + displacement + GPMC_CONFIG6) = 0x00000000; // No back to back cycle restrictions
		*(gpmc + displacement + GPMC_CONFIG7) = 0x00000e50; // CS0: Set base address 0x10000000, 32MB region, and enable CS

		gpmc_unmapregisters();
	}
}

static void io_setup(void)
{
	printf("sizeof int:\t%d\n", sizeof(int));

	/* open /dev/mem */
	if ((mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) {
		printf("can't open /dev/mem \n");
		exit (-1);
	}

	/* mmap GPIO */
	gpio_map = (char *)mmap(
		0,
		MEMORY_SIZE,
		PROT_READ|PROT_WRITE,
		MAP_SHARED,
		mem_fd,
		0x10000000
	);

	if (gpio_map == MAP_FAILED) {
		printf("mmap error %d\n", (int)gpio_map);
		exit (-1);
	}

	// Always use volatile pointer!
	gpio = (volatile unsigned *)gpio_map;
	gpio_char = (volatile unsigned char *)gpio_map;

	// Select a test from the following blocks of code...

// 	// DEBUG ONLY
// 	// Clear out the mapped memory
// 	int i;
// 	for (i=0;i<0x3ff; i++) {
// 		*(gpio + i) = 0x00000000;
// 	}

	// DEBUG ONLY
	// Fill the mapped memory with a test pattern
// 	int j;
// 	for (j=0;j<0x00001000; j++) {
// 		*(gpio + j) = j;
// 	}
// 	int j;
// 	for (j=0;j<0x3ff; j++) {
// 		*(gpio + j) = j;
// 	}

	// DEBUG ONLY
	// Looping memory test
	unsigned int test_base = (MEMORY_SIZE/2);
	unsigned int test_length = (MEMORY_SIZE/2);
	unsigned int total_errors;
	unsigned char error_count[MEMORY_SIZE];
	int i;
	int loop;
	unsigned int overall_total_errors;
	overall_total_errors = 0;
	for (loop=0; loop<10;loop++) {
		printf("Memory test loop %d\n", loop);
		for (i=0; i<test_length; i++) {
			error_count[i] = 0;
		}
		printf("\tTesting inversion pattern\n");
		// Test with 0xaa
		for (i=0;i<test_length; i++) {
			*(gpio_char + test_base + i) = 0xaa;
		}
		for (i=0;i<test_length; i++) {
			unsigned char result = *(gpio_char + test_base + i);
			if ((result != 0xaa)) {
				error_count[i] = error_count[i] + 1;
				printf("\terror detected at offset 0x%02x (was 0x%02x, expected 0x%02x, second read attempt returned 0x%02x)\n", i, result, 0xaa, (*(gpio_char + test_base + i)));
			}
		}
		// Test with 0x55
		for (i=0;i<test_length; i++) {
			*(gpio_char + test_base + i) = 0x55;
		}
		for (i=0;i<test_length; i++) {
			unsigned char result = *(gpio_char + test_base + i);
			if ((result != 0x55)) {
				error_count[i] = error_count[i] + 1;
				printf("\terror detected at offset 0x%02x (was 0x%02x, expected 0x%02x, second read attempt returned 0x%02x)\n", i, result, 0x55, (*(gpio_char + test_base + i)));
			}
		}
		total_errors = 0;
		for (i=0; i<test_length; i++) {
			total_errors = total_errors + error_count[i];
			if (error_count[i] > 0) {
				printf("\t%d\terror(s) found at offset 0x%02x\n", error_count[i], i);
			}
		}

		printf("\tTesting all ones/zeros\n");
		// Test with 0xff
		for (i=0;i<test_length; i++) {
			*(gpio_char + test_base + i) = 0xff;
		}
		for (i=0;i<test_length; i++) {
			unsigned char result = *(gpio_char + test_base + i);
			if ((result != 0xff)) {
				error_count[i] = error_count[i] + 1;
				printf("\terror detected at offset 0x%02x (was 0x%02x, expected 0x%02x, second read attempt returned 0x%02x)\n", i, result, 0xff, (*(gpio_char + test_base + i)));
			}
		}
		// Test with 0x00
		for (i=0;i<test_length; i++) {
			*(gpio_char + test_base + i) = 0x00;
		}
		for (i=0;i<test_length; i++) {
			unsigned char result = *(gpio_char + test_base + i);
			if ((result != 0x00)) {
				error_count[i] = error_count[i] + 1;
				printf("\terror detected at offset 0x%02x (was 0x%02x, expected 0x%02x, second read attempt returned 0x%02x)\n", i, result, 0x00, (*(gpio_char + test_base + i)));
			}
		}

		printf("\tTesting alternating ones/zeros\n");
		// Test with 0xff
		for (i=0;i<test_length; i=i+2) {
			*(gpio_char + test_base + i) = 0xff;
			*(gpio_char + test_base + i + 1) = 0x00;
		}
		for (i=0;i<test_length; i=i+2) {
			unsigned char result;
			result = *(gpio_char + test_base + i);
			if ((result != 0xff)) {
				error_count[i] = error_count[i] + 1;
				printf("\terror detected at offset 0x%02x (was 0x%02x, expected 0x%02x, second read attempt returned 0x%02x)\n", i, result, 0xff, (*(gpio_char + test_base + i)));
			}
			result = *(gpio_char + test_base + i + 1);
			if ((result != 0x00)) {
				error_count[i] = error_count[i] + 1;
				printf("\terror detected at offset 0x%02x (was 0x%02x, expected 0x%02x, second read attempt returned 0x%02x)\n", i, result, 0x00, (*(gpio_char + test_base + i)));
			}
		}

		total_errors = 0;
		for (i=0; i<test_length; i++) {
			total_errors = total_errors + error_count[i];
			if (error_count[i] > 0) {
				printf("\t%d\terror(s) found at offset 0x%02x\n", error_count[i], i);
			}
		}
		printf("\tTest region size:\t%d\n", test_length);
		printf("\tTotal errors found:\t%d\n", total_errors);
		fflush(stdout);
		overall_total_errors = overall_total_errors + total_errors;
	}
	for (i=0;i<MEMORY_SIZE; i++) {
		*(gpio_char + i) = 0;
	}
	printf("Total errors found over all loops:\t%d\n", overall_total_errors);
	fflush(stdout);
	return;
	

	int j;
	for (j=0;j<MEMORY_SIZE; j++) {
		*(gpio_char + j) = ((unsigned char)j);
	}

	// DEBUG ONLY
	// Prints the contents of the mapped memory
	int k;
	for (k=0;k<(MEMORY_SIZE/4); k++) {
		printf("0x%08x\t%08x\n", k, *(gpio + k));
	}
	fflush(stdout);

// 	// DEBUG ONLY
// 	// Excercise the memory space
// 	int l;
// 	while (1) {
// 		for (l=0;l<(MEMORY_SIZE/4); l++) {
// 			k = *(gpio + l);
// 		}
// 	}

// 	while (1) {
// 		printf("0x%08x\t0x%08x\t0x%08x\t0x%08x\r", *(gpio + 0), *(gpio + 1), *(gpio + 2), *(gpio + 3));
// 		usleep(1);
// 	}

// 	while (1) {
// 		printf("0x%08x\t0x%08x\t0x%08x\t0x%08x\r", *(gpio + 3), *(gpio + 2), *(gpio + 1), *(gpio + 0));
// 		usleep(1);
// 	}

// 	printf("0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\n\r", *(gpio_char + 0), *(gpio_char + 0), *(gpio_char + 0), *(gpio_char + 0), *(gpio_char + 0), *(gpio_char + 0), *(gpio_char + 0), *(gpio_char + 0));
// 
	while (1) {
//		printf("0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\r", *(gpio_char + 0), *(gpio_char + 1), *(gpio_char + 2), *(gpio_char + 3), *(gpio_char + 4), *(gpio_char + 5), *(gpio_char + 6), *(gpio_char + 7));
//		printf("0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\r", *(gpio_char + 0), *(gpio_char + 1), *(gpio_char + 2), *(gpio_char + 3), *(gpio_char + 0x1000), *(gpio_char + 0x1001), *(gpio_char + 0x1002), *(gpio_char + 0x1003));
		printf("0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\r", *(gpio_char + 0), *(gpio_char + 1), *(gpio_char + 2), *(gpio_char + 3), *(gpio_char + 0x4000), *(gpio_char + 0x4001), *(gpio_char + 0x4002), *(gpio_char + 0x4003));
// 		printf("0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\t0x%02x\r", *(gpio_char + 0x4000), *(gpio_char + 0x4001), *(gpio_char + 0x4002), *(gpio_char + 0x4003), *(gpio_char + 0x4000), *(gpio_char + 0x4001), *(gpio_char + 0x4002), *(gpio_char + 0x4003));
		usleep(10);
	}
}

static void io_shutdown(void)
{
	//
}

/** END: Low-Level I/O Implementation **/

int main(int argc, char **argv)
{
	gpmc_setup();
	printf("GPMC setup complete!\n"); fflush(stdout);
	io_setup();
	return 0;
}