#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/mman.h>

#include "card.h"

/* Read a 16-bit unsigned int from a pci id file */
unsigned short read_pci_id(char *device_path, char *field)
{
	char buf[16];
	char file_path[PATH_MAX];
	
	strcpy(file_path, device_path);
	strcat(file_path, field);
	
	FILE *fp = fopen(file_path, "r");
	
	if (fp == NULL)
		return 0;
		
	if (fgets(buf, sizeof(buf), fp) == NULL) {
		fclose(fp);
		return 0;
	}
	
	fclose(fp);
	
	return (unsigned short)strtoul(buf, NULL, 16);
}

/* Read a PCI ID from the name of an Nvidia i2c device */
char *read_nvidia_pci_address(char *device_path)
{
	char file_path[PATH_MAX];
	
	char *ret = calloc(16 + 1, sizeof(char)); /* assuming pci ids could look as large as 00000000:0C:00.0 */
	
	strcpy(file_path, device_path);
	strcat(file_path, "/name");
	
	FILE *fp = fopen(file_path, "r");
	
	if (fp == NULL) {
		free(ret);
		return NULL;
	}
	
	fscanf(fp, "NVIDIA i2c adapter %*u at %16s", ret);
	fclose(fp);
	
	if (strlen(ret) == 0) {
		free(ret);
		return NULL;
	}
	
	return ret;
}

/* Open an mmap to the BAR0 of a PCI device using its /sys/bus/pci device files */
void mmap_bar0(struct card_info *card)
{
	char resource_path[PATH_MAX];
	snprintf(resource_path, sizeof(resource_path), "%s/resource0", card->pci_dev_path);
	
	/* Open FD on the resource file */
	int fd = open(resource_path, O_RDONLY);
	if (fd == -1) {
		printf("Unable to open %s\n", resource_path);
		card->bar0_mmap = NULL;
		return;
	}

	/* Figure out the size of BAR0 fomr the size of the resource file */
	struct stat st;
	if (fstat(fd, &st) == -1) {
		printf("Unable to stat %s\n", resource_path);
		close(fd);
		card->bar0_mmap = NULL;
		return;
	}

	/* mmap the bar0 resource file */
	card->bar0_mmap = mmap(0, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
	if (card->bar0_mmap == MAP_FAILED) {
		printf("Unable to mmap %s\n", resource_path);
		card->bar0_mmap = NULL;
	}

	/* mmap stays open after the FD has been closed */
	close(fd);
}