TODO:
	- Rx block size is limited to < 2048, hardware bug?
	- Group size is limited to < page size, kernel alloc/mmap API issues
	- test whether Tx is transmitting data from provided buffers
	- handle device unplug case
	- handle temperature above threshold
	- use bus address instead of physical address for DMA
	- support for snapshot mode
	- audit userspace interfaces
	- get reserved major/minor if needed

Sample Code:

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <poll.h>
#include <stdio.h>
#include <error.h>
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>

#include <sysfs/libsysfs.h>

#include <poch.h>

struct pconsume {
	uint32_t * offsets;
	uint32_t nfetch;
	uint32_t nflush;
};

uint32_t offsets[10];

void process_group(unsigned char *buf, uint32_t size)
{
	uint16_t *buf16 = (uint16_t *)buf;

	printf("RX: %p %u %04x %04x %04x %04x %04x %04x\n", buf, size,
	       buf16[0], buf16[1], buf16[2], buf16[3], buf16[4], buf16[5]);
}

int main()
{
	struct sysfs_attribute *attr;
	char *path;
	int ret;
	unsigned long mmap_size;
	int fd;
	unsigned char *cbuf;

	uint32_t nflush;
	struct pollfd poll_fds;
	int count = 0;
	int i;

	path = "/sys/class/pocketchange/poch0/ch0/block_size";
	attr = sysfs_open_attribute(path);
	ret = sysfs_write_attribute(attr, "256", strlen("256"));
	if (ret == -1)
		error(1, errno, "error writing attribute %s", path);
	sysfs_close_attribute(attr);

	path = "/sys/class/pocketchange/poch0/ch0/group_size";
	attr = sysfs_open_attribute(path);
	ret = sysfs_write_attribute(attr, "4096", strlen("4096"));
	if (ret == -1)
		error(1, errno, "error writing attribute %s", path);
	sysfs_close_attribute(attr);

	path = "/sys/class/pocketchange/poch0/ch0/group_count";
	attr = sysfs_open_attribute(path);
	ret = sysfs_write_attribute(attr, "64", strlen("64"));
	if (ret == -1)
		error(1, errno, "error writing attribute %s", path);
	sysfs_close_attribute(attr);

	fd = open("/dev/ch0", O_RDWR);
	if (fd == -1)
		error(1, errno, "error opening device node");

	path = "/sys/class/pocketchange/poch0/ch0/mmap_size";
	attr = sysfs_open_attribute(path);
	ret = sysfs_read_attribute(attr);
	if (ret == -1)
		error(1, errno, "error reading attribute %s", path);
	printf("%s", attr->value);
	sscanf(attr->value, "%lu", &mmap_size);
	sysfs_close_attribute(attr);

	cbuf = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
		    MAP_PRIVATE, fd, 0);
	if (cbuf == MAP_FAILED)
		error(1, errno, "error mapping DMA buffers");

	ret = ioctl(fd, POCH_IOC_TRANSFER_START, 0);
	if (ret == -1)
		error(1, errno, "error starting transfer");

	nflush = 0;
	while (1) {
		struct pconsume consume;

		consume.offsets = offsets;
		consume.nfetch = 10;
		consume.nflush = nflush;

		ret = ioctl(fd, POCH_IOC_CONSUME, &consume);
		if (ret == -1)
			error(1, errno, "error consuming groups");

		nflush = consume.nfetch;

		for (i = 0; i < nflush; i++) {
			process_group(cbuf + consume.offsets[i], 4096);

			count++;
			if (count == 1000)
				break;
		}

		if (count == 1000)
			break;
	}

	ret = ioctl(fd, POCH_IOC_TRANSFER_STOP, 0);
	if (ret == -1)
		error(1, errno, "error starting transfer");

	return 0;
}

Please send patches to Greg Kroah-Hartman <greg@kroah.com> and
Vijay Kumar <vijaykumar@bravegnu.org> and Jaya Kumar <jayakumar.lkml@gmail.com>