bfgminer/driver-icarus.c

/*
 * Copyright 2012-2013 Luke Dashjr
 * Copyright 2012 Xiangfu
 * Copyright 2012 Andrew Smith
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 3 of the License, or (at your option)
 * any later version.  See COPYING for more details.
 */

/*
 * Those code should be works fine with V2 and V3 bitstream of Icarus.
 * Operation:
 *   No detection implement.
 *   Input: 64B = 32B midstate + 20B fill bytes + last 12 bytes of block head.
 *   Return: send back 32bits immediately when Icarus found a valid nonce.
 *           no query protocol implemented here, if no data send back in ~11.3
 *           seconds (full cover time on 32bit nonce range by 380MH/s speed)
 *           just send another work.
 * Notice:
 *   1. Icarus will start calculate when you push a work to them, even they
 *      are busy.
 *   2. The 2 FPGAs on Icarus will distribute the job, one will calculate the
 *      0 ~ 7FFFFFFF, another one will cover the 80000000 ~ FFFFFFFF.
 *   3. It's possible for 2 FPGAs both find valid nonce in the meantime, the 2
 *      valid nonce will all be send back.
 *   4. Icarus will stop work when: a valid nonce has been found or 32 bits
 *      nonce range is completely calculated.
 */

#include "config.h"

#ifdef WIN32
#include <winsock2.h>
#endif

#include <limits.h>
#include <pthread.h>
#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <dirent.h>
#include <unistd.h>
#ifndef WIN32
  #include <termios.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #ifndef O_CLOEXEC
    #define O_CLOEXEC 0
  #endif
#else
  #include <windows.h>
  #include <io.h>
#endif
#ifdef HAVE_SYS_EPOLL_H
  #include <sys/epoll.h>
  #define HAVE_EPOLL
#endif

#include "compat.h"
#include "dynclock.h"
#include "elist.h"
#include "icarus-common.h"
#include "miner.h"
#include "fpgautils.h"

// The serial I/O speed - Linux uses a define 'B115200' in bits/termios.h
#define ICARUS_IO_SPEED 115200

// The size of a successful nonce read
#define ICARUS_READ_SIZE 4

// Ensure the sizes are correct for the Serial read
#if (ICARUS_READ_SIZE != 4)
#error ICARUS_READ_SIZE must be 4
#endif
#define ASSERT1(condition) __maybe_unused static char sizeof_uint32_t_must_be_4[(condition)?1:-1]
ASSERT1(sizeof(uint32_t) == 4);

#define ICARUS_READ_TIME(baud) ((double)ICARUS_READ_SIZE * (double)8.0 / (double)(baud))

// In timing mode: Default starting value until an estimate can be obtained
// 5 seconds allows for up to a ~840MH/s device
#define ICARUS_READ_COUNT_TIMING	(5 * TIME_FACTOR)

// For a standard Icarus REV3
#define ICARUS_REV3_HASH_TIME 0.00000000264083

// Icarus Rev3 doesn't send a completion message when it finishes
// the full nonce range, so to avoid being idle we must abort the
// work (by starting a new work) shortly before it finishes
//
// Thus we need to estimate 2 things:
//	1) How many hashes were done if the work was aborted
//	2) How high can the timeout be before the Icarus is idle,
//		to minimise the number of work started
//	We set 2) to 'the calculated estimate' - 1
//	to ensure the estimate ends before idle
//
// The simple calculation used is:
//	Tn = Total time in seconds to calculate n hashes
//	Hs = seconds per hash
//	Xn = number of hashes
//	W  = code overhead per work
//
// Rough but reasonable estimate:
//	Tn = Hs * Xn + W	(of the form y = mx + b)
//
// Thus:
//	Line of best fit (using least squares)
//
//	Hs = (n*Sum(XiTi)-Sum(Xi)*Sum(Ti))/(n*Sum(Xi^2)-Sum(Xi)^2)
//	W = Sum(Ti)/n - (Hs*Sum(Xi))/n
//
// N.B. W is less when aborting work since we aren't waiting for the reply
//	to be transferred back (ICARUS_READ_TIME)
//	Calculating the hashes aborted at n seconds is thus just n/Hs
//	(though this is still a slight overestimate due to code delays)
//

// Both below must be exceeded to complete a set of data
// Minimum how long after the first, the last data point must be
#define HISTORY_SEC 60
// Minimum how many points a single ICARUS_HISTORY should have
#define MIN_DATA_COUNT 5
// The value above used is doubled each history until it exceeds:
#define MAX_MIN_DATA_COUNT 100

#if (TIME_FACTOR != 10)
#error TIME_FACTOR must be 10
#endif

static struct timeval history_sec = { HISTORY_SEC, 0 };

static const char *MODE_DEFAULT_STR = "default";
static const char *MODE_SHORT_STR = "short";
static const char *MODE_LONG_STR = "long";
static const char *MODE_VALUE_STR = "value";
static const char *MODE_UNKNOWN_STR = "unknown";

#define END_CONDITION 0x0000ffff
#define DEFAULT_DETECT_THRESHOLD 1

// Looking for options in --icarus-timing and --icarus-options:
//
// Code increments this each time we start to look at a device
// However, this means that if other devices are checked by
// the Icarus code (e.g. BFL) they will count in the option offset
//
// This, however, is deterministic so that's OK
//
// If we were to increment after successfully finding an Icarus
// that would be random since an Icarus may fail and thus we'd
// not be able to predict the option order
//
// This also assumes that serial_detect() checks them sequentially
// and in the order specified on the command line
//
static int option_offset = -1;

struct device_api icarus_api;

extern void convert_icarus_to_cairnsmore(struct cgpu_info *);

static void rev(unsigned char *s, size_t l)
{
	size_t i, j;
	unsigned char t;

	for (i = 0, j = l - 1; i < j; i++, j--) {
		t = s[i];
		s[i] = s[j];
		s[j] = t;
	}
}

#define icarus_open2(devpath, baud, purge)  serial_open(devpath, baud, ICARUS_READ_FAULT_DECISECONDS, purge)
#define icarus_open(devpath, baud)  icarus_open2(devpath, baud, false)

#define ICA_GETS_ERROR -1
#define ICA_GETS_OK 0
#define ICA_GETS_RESTART 1
#define ICA_GETS_TIMEOUT 2

int icarus_gets(unsigned char *buf, int fd, struct timeval *tv_finish, struct thr_info *thr, int read_count)
{
	ssize_t ret = 0;
	int rc = 0;
	int epollfd = -1;
	int epoll_timeout = ICARUS_READ_FAULT_DECISECONDS * 100;
	int read_amount = ICARUS_READ_SIZE;
	bool first = true;

#ifdef HAVE_EPOLL
	struct epoll_event ev = {
		.events = EPOLLIN,
		.data.fd = fd,
	};
	struct epoll_event evr[2];
	if (thr && thr->work_restart_notifier[1] != -1) {
	epollfd = epoll_create(2);
	if (epollfd != -1) {
		if (-1 == epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev)) {
			close(epollfd);
			epollfd = -1;
		}
		{
			ev.data.fd = thr->work_restart_notifier[0];
			if (-1 == epoll_ctl(epollfd, EPOLL_CTL_ADD, thr->work_restart_notifier[0], &ev))
				applog(LOG_ERR, "Icarus: Error adding work restart fd to epoll");
			else
			{
				epoll_timeout *= read_count;
				read_count = 1;
			}
		}
	}
	else
		applog(LOG_ERR, "Icarus: Error creating epoll");
	}
#endif

	// Read reply 1 byte at a time to get earliest tv_finish
	while (true) {
#ifdef HAVE_EPOLL
		if (epollfd != -1 && (ret = epoll_wait(epollfd, evr, 2, epoll_timeout)) != -1)
		{
			if (ret == 1 && evr[0].data.fd == fd)
				ret = read(fd, buf, 1);
			else
			{
				if (ret)
					notifier_read(thr->work_restart_notifier);
				ret = 0;
			}
		}
		else
#endif
		ret = read(fd, buf, 1);
		if (ret < 0)
			return ICA_GETS_ERROR;

		if (first)
			gettimeofday(tv_finish, NULL);

		if (ret >= read_amount)
		{
			if (epollfd != -1)
				close(epollfd);
			return ICA_GETS_OK;
		}

		if (ret > 0) {
			buf += ret;
			read_amount -= ret;
			first = false;
			continue;
		}
			
		if (thr && thr->work_restart) {
			if (epollfd != -1)
				close(epollfd);
			if (opt_debug) {
				applog(LOG_DEBUG,
					"Icarus Read: Interrupted by work restart");
			}
			return ICA_GETS_RESTART;
		}

		rc++;
		if (rc >= read_count) {
			if (epollfd != -1)
				close(epollfd);
			if (opt_debug) {
				applog(LOG_DEBUG,
					"Icarus Read: No data in %.2f seconds",
					(float)rc * epoll_timeout / 1000.);
			}
			return ICA_GETS_TIMEOUT;
		}
	}
}

static int icarus_write(int fd, const void *buf, size_t bufLen)
{
	size_t ret;

	ret = write(fd, buf, bufLen);
	if (unlikely(ret != bufLen))
		return 1;

	return 0;
}

#define icarus_close(fd) close(fd)

static void do_icarus_close(struct thr_info *thr)
{
	struct cgpu_info *icarus = thr->cgpu;
	icarus_close(icarus->device_fd);
	icarus->device_fd = -1;
}

static const char *timing_mode_str(enum timing_mode timing_mode)
{
	switch(timing_mode) {
	case MODE_DEFAULT:
		return MODE_DEFAULT_STR;
	case MODE_SHORT:
		return MODE_SHORT_STR;
	case MODE_LONG:
		return MODE_LONG_STR;
	case MODE_VALUE:
		return MODE_VALUE_STR;
	default:
		return MODE_UNKNOWN_STR;
	}
}

static void set_timing_mode(int this_option_offset, struct cgpu_info *icarus)
{
	struct ICARUS_INFO *info = icarus->cgpu_data;
	double Hs;
	char buf[BUFSIZ+1];
	char *ptr, *comma, *eq;
	size_t max;
	int i;

	if (opt_icarus_timing == NULL)
		buf[0] = '\0';
	else {
		ptr = opt_icarus_timing;
		for (i = 0; i < this_option_offset; i++) {
			comma = strchr(ptr, ',');
			if (comma == NULL)
				break;
			ptr = comma + 1;
		}

		comma = strchr(ptr, ',');
		if (comma == NULL)
			max = strlen(ptr);
		else
			max = comma - ptr;

		if (max > BUFSIZ)
			max = BUFSIZ;
		strncpy(buf, ptr, max);
		buf[max] = '\0';
	}

	info->read_count = 0;

	if (strcasecmp(buf, MODE_SHORT_STR) == 0) {
		info->read_count = ICARUS_READ_COUNT_TIMING;

		info->timing_mode = MODE_SHORT;
		info->do_icarus_timing = true;
	} else if (strcasecmp(buf, MODE_LONG_STR) == 0) {
		info->read_count = ICARUS_READ_COUNT_TIMING;

		info->timing_mode = MODE_LONG;
		info->do_icarus_timing = true;
	} else if ((Hs = atof(buf)) != 0) {
		info->Hs = Hs / NANOSEC;
		info->fullnonce = info->Hs * (((double)0xffffffff) + 1);

		if ((eq = strchr(buf, '=')) != NULL)
			info->read_count = atoi(eq+1);

		if (info->read_count < 1)
			info->read_count = (int)(info->fullnonce * TIME_FACTOR) - 1;

		if (unlikely(info->read_count < 1))
			info->read_count = 1;

		info->timing_mode = MODE_VALUE;
		info->do_icarus_timing = false;
	} else {
		// Anything else in buf just uses DEFAULT mode

		info->fullnonce = info->Hs * (((double)0xffffffff) + 1);

		if ((eq = strchr(buf, '=')) != NULL)
			info->read_count = atoi(eq+1);

		int def_read_count = ICARUS_READ_COUNT_TIMING;

		if (info->timing_mode == MODE_DEFAULT) {
			if (icarus->api == &icarus_api) {
				info->do_default_detection = 0x10;
			} else {
				def_read_count = (int)(info->fullnonce * TIME_FACTOR) - 1;
			}

			info->do_icarus_timing = false;
		}
		if (info->read_count < 1)
			info->read_count = def_read_count;
	}

	info->min_data_count = MIN_DATA_COUNT;

	applog(LOG_DEBUG, "%"PRIpreprv": Init: mode=%s read_count=%d Hs=%e",
		icarus->proc_repr,
		timing_mode_str(info->timing_mode), info->read_count, info->Hs);
}

static uint32_t mask(int work_division)
{
	uint32_t nonce_mask = 0x7fffffff;

	// yes we can calculate these, but this way it's easy to see what they are
	switch (work_division) {
	case 1:
		nonce_mask = 0xffffffff;
		break;
	case 2:
		nonce_mask = 0x7fffffff;
		break;
	case 4:
		nonce_mask = 0x3fffffff;
		break;
	case 8:
		nonce_mask = 0x1fffffff;
		break;
	default:
		quit(1, "Invalid2 icarus-options for work_division (%d) must be 1, 2, 4 or 8", work_division);
	}

	return nonce_mask;
}

static void get_options(int this_option_offset, struct ICARUS_INFO *info)
{
	int *baud = &info->baud;
	int *work_division = &info->work_division;
	int *fpga_count = &info->fpga_count;

	char buf[BUFSIZ+1];
	char *ptr, *comma, *colon, *colon2;
	size_t max;
	int i, tmp;

	if (opt_icarus_options == NULL)
		buf[0] = '\0';
	else {
		ptr = opt_icarus_options;
		for (i = 0; i < this_option_offset; i++) {
			comma = strchr(ptr, ',');
			if (comma == NULL)
				break;
			ptr = comma + 1;
		}

		comma = strchr(ptr, ',');
		if (comma == NULL)
			max = strlen(ptr);
		else
			max = comma - ptr;

		if (max > BUFSIZ)
			max = BUFSIZ;
		strncpy(buf, ptr, max);
		buf[max] = '\0';
	}

	if (*buf) {
		colon = strchr(buf, ':');
		if (colon)
			*(colon++) = '\0';

		if (*buf) {
			tmp = atoi(buf);
			switch (tmp) {
			case 115200:
				*baud = 115200;
				break;
			case 57600:
				*baud = 57600;
				break;
			default:
				quit(1, "Invalid icarus-options for baud (%s) must be 115200 or 57600", buf);
			}
		}

		if (colon && *colon) {
			colon2 = strchr(colon, ':');
			if (colon2)
				*(colon2++) = '\0';

			if (*colon) {
				info->user_set |= 1;
				tmp = atoi(colon);
				if (tmp == 1 || tmp == 2 || tmp == 4 || tmp == 8) {
					*work_division = tmp;
					*fpga_count = tmp;	// default to the same
				} else {
					quit(1, "Invalid icarus-options for work_division (%s) must be 1, 2, 4 or 8", colon);
				}
			}

			if (colon2 && *colon2) {
			  colon = strchr(colon2, ':');
			  if (colon)
					*(colon++) = '\0';

			  if (*colon2) {
				info->user_set |= 2;
				tmp = atoi(colon2);
				if (tmp > 0 && tmp <= *work_division)
					*fpga_count = tmp;
				else {
					quit(1, "Invalid icarus-options for fpga_count (%s) must be >0 and <=work_division (%d)", colon2, *work_division);
				}
			  }

			  if (colon && *colon) {
					colon2 = strchr(colon, '-') ?: "";
					if (*colon2)
						*(colon2++) = '\0';
					if (strchr(colon, 'r'))
						info->quirk_reopen = 2;
					if (strchr(colon2, 'r'))
						info->quirk_reopen = 0;
			  }
			}
		}
	}
}

bool icarus_detect_custom(const char *devpath, struct device_api *api, struct ICARUS_INFO *info)
{
	int this_option_offset = ++option_offset;

	struct timeval tv_start, tv_finish;
	int fd;

	// Block 171874 nonce = (0xa2870100) = 0x000187a2
	// N.B. golden_ob MUST take less time to calculate
	//	than the timeout set in icarus_open()
	//	This one takes ~0.53ms on Rev3 Icarus
	const char golden_ob[] =
		"4679ba4ec99876bf4bfe086082b40025"
		"4df6c356451471139a3afa71e48f544a"
		"00000000000000000000000000000000"
		"0000000087320b1a1426674f2fa722ce";
	/* NOTE: This gets sent to basically every port specified in --scan-serial,
	 *       even ones that aren't Icarus; be sure they can all handle it, when
	 *       this is changed...
	 *       BitForce: Ignores entirely
	 *       ModMiner: Starts (useless) work, gets back to clean state
	 */

	const char golden_nonce[] = "000187a2";
	const uint32_t golden_nonce_val = 0x000187a2;

	unsigned char ob_bin[64], nonce_bin[ICARUS_READ_SIZE];
	char *nonce_hex;

	get_options(this_option_offset, info);

	int baud = info->baud;
	int work_division = info->work_division;
	int fpga_count = info->fpga_count;

	applog(LOG_DEBUG, "Icarus Detect: Attempting to open %s", devpath);

	fd = icarus_open2(devpath, baud, true);
	if (unlikely(fd == -1)) {
		applog(LOG_DEBUG, "Icarus Detect: Failed to open %s", devpath);
		return false;
	}

	hex2bin(ob_bin, golden_ob, sizeof(ob_bin));
	icarus_write(fd, ob_bin, sizeof(ob_bin));
	gettimeofday(&tv_start, NULL);

	memset(nonce_bin, 0, sizeof(nonce_bin));
	icarus_gets(nonce_bin, fd, &tv_finish, NULL, 1);

	icarus_close(fd);

	nonce_hex = bin2hex(nonce_bin, sizeof(nonce_bin));
	if (strncmp(nonce_hex, golden_nonce, 8)) {
		applog(LOG_DEBUG,
			"Icarus Detect: "
			"Test failed at %s: get %s, should: %s",
			devpath, nonce_hex, golden_nonce);
		free(nonce_hex);
		return false;
	}
	applog(LOG_DEBUG,
		"Icarus Detect: "
		"Test succeeded at %s: got %s",
			devpath, nonce_hex);
	free(nonce_hex);

	if (serial_claim(devpath, api)) {
		const char *claimedby = serial_claim(devpath, api)->dname;
		applog(LOG_DEBUG, "Icarus device %s already claimed by other driver: %s", devpath, claimedby);
		return false;
	}

	/* We have a real Icarus! */
	struct cgpu_info *icarus;
	icarus = calloc(1, sizeof(struct cgpu_info));
	icarus->api = api;
	icarus->device_path = strdup(devpath);
	icarus->device_fd = -1;
	icarus->threads = 1;
	add_cgpu(icarus);

	applog(LOG_INFO, "Found %"PRIpreprv" at %s",
		icarus->proc_repr,
		devpath);

	applog(LOG_DEBUG, "%"PRIpreprv": Init: baud=%d work_division=%d fpga_count=%d",
		icarus->proc_repr,
		baud, work_division, fpga_count);

	icarus->cgpu_data = info;

	info->nonce_mask = mask(work_division);

	info->golden_hashes = (golden_nonce_val & info->nonce_mask) * fpga_count;
	timersub(&tv_finish, &tv_start, &(info->golden_tv));

	set_timing_mode(this_option_offset, icarus);

	return true;
}

static bool icarus_detect_one(const char *devpath)
{
	struct ICARUS_INFO *info = calloc(1, sizeof(struct ICARUS_INFO));
	if (unlikely(!info))
		quit(1, "Failed to malloc ICARUS_INFO");

	info->baud = ICARUS_IO_SPEED;
	info->work_division = 2;
	info->fpga_count = 2;
	info->quirk_reopen = 1;
	info->Hs = ICARUS_REV3_HASH_TIME;
	info->timing_mode = MODE_DEFAULT;

	if (!icarus_detect_custom(devpath, &icarus_api, info)) {
		free(info);
		return false;
	}
	return true;
}

static void icarus_detect()
{
	serial_detect(&icarus_api, icarus_detect_one);
}

static bool icarus_prepare(struct thr_info *thr)
{
	struct cgpu_info *icarus = thr->cgpu;
	struct ICARUS_INFO *info = icarus->cgpu_data;

	struct timeval now;

	icarus->device_fd = -1;

	int fd = icarus_open2(icarus->device_path, info->baud, true);
	if (unlikely(-1 == fd)) {
		applog(LOG_ERR, "Failed to open Icarus on %s",
		       icarus->device_path);
		return false;
	}

	icarus->device_fd = fd;

	applog(LOG_INFO, "Opened Icarus on %s", icarus->device_path);
	gettimeofday(&now, NULL);
	get_datestamp(icarus->init, &now);

	struct icarus_state *state;
	thr->cgpu_data = state = calloc(1, sizeof(*state));
	state->firstrun = true;

#ifdef HAVE_EPOLL
	int epollfd = epoll_create(2);
	if (epollfd != -1)
	{
		close(epollfd);
		notifier_init(thr->work_restart_notifier);
	}
#endif

	icarus->status = LIFE_INIT2;
	
	return true;
}

static bool icarus_reopen(struct cgpu_info *icarus, struct icarus_state *state, int *fdp)
{
	struct ICARUS_INFO *info = icarus->cgpu_data;

	// Reopen the serial port to workaround a USB-host-chipset-specific issue with the Icarus's buggy USB-UART
	icarus_close(icarus->device_fd);
	*fdp = icarus->device_fd = icarus_open(icarus->device_path, info->baud);
	if (unlikely(-1 == *fdp)) {
		applog(LOG_ERR, "%"PRIpreprv": Failed to reopen on %s", icarus->proc_repr, icarus->device_path);
		dev_error(icarus, REASON_DEV_COMMS_ERROR);
		state->firstrun = true;
		return false;
	}
	return true;
}

static bool icarus_start_work(struct thr_info *thr, const unsigned char *ob_bin)
{
	struct cgpu_info *icarus = thr->cgpu;
	struct icarus_state *state = thr->cgpu_data;
	int fd = icarus->device_fd;
	int ret;
	char *ob_hex;

	gettimeofday(&state->tv_workstart, NULL);

	ret = icarus_write(fd, ob_bin, 64);
	if (ret) {
		do_icarus_close(thr);
		applog(LOG_ERR, "ICA%i: Comms error", icarus->device_id);
		dev_error(icarus, REASON_DEV_COMMS_ERROR);
		return false;	/* This should never happen */
	}

	if (opt_debug) {
		ob_hex = bin2hex(ob_bin, 64);
		applog(LOG_DEBUG, "%"PRIpreprv" sent: %s",
			icarus->proc_repr,
			ob_hex);
		free(ob_hex);
	}

	return true;
}

static int64_t icarus_scanhash(struct thr_info *thr, struct work *work,
				__maybe_unused int64_t max_nonce)
{
	struct cgpu_info *icarus;
	int fd;
	int ret;

	struct ICARUS_INFO *info;

	unsigned char ob_bin[64] = {0}, nonce_bin[ICARUS_READ_SIZE] = {0};
	uint32_t nonce;
	int64_t hash_count;
	struct timeval tv_start, elapsed;
	struct timeval tv_history_start, tv_history_finish;
	double Ti, Xi;
	int curr_hw_errors, i;
	bool was_hw_error;
	bool was_first_run;

	struct ICARUS_HISTORY *history0, *history;
	int count;
	double Hs, W, fullnonce;
	int read_count;
	int64_t estimate_hashes;
	uint32_t values;
	int64_t hash_count_range;

	elapsed.tv_sec = elapsed.tv_usec = 0;

	icarus = thr->cgpu;
	struct icarus_state *state = thr->cgpu_data;
	was_first_run = state->firstrun;

	// Prepare the next work immediately
	memcpy(ob_bin, work->midstate, 32);
	memcpy(ob_bin + 52, work->data + 64, 12);
	if (!(memcmp(&ob_bin[56], "\xff\xff\xff\xff", 4)
	   || memcmp(&ob_bin, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 32))) {
		// This sequence is used on cairnsmore bitstreams for commands, NEVER send it otherwise
		applog(LOG_WARNING, "%"PRIpreprv": Received job attempting to send a command, corrupting it!",
		       icarus->proc_repr);
		ob_bin[56] = 0;
	}
	rev(ob_bin, 32);
	rev(ob_bin + 52, 12);

	// Wait for the previous run's result
	fd = icarus->device_fd;
	info = icarus->cgpu_data;

	if (!state->firstrun) {
		if (state->changework)
		{
			state->changework = false;
			ret = ICA_GETS_RESTART;
		}
		else
		{
			/* Icarus will return 4 bytes (ICARUS_READ_SIZE) nonces or nothing */
			ret = icarus_gets(nonce_bin, fd, &state->tv_workfinish, thr, info->read_count);
			switch (ret) {
				case ICA_GETS_RESTART:
					// The prepared work is invalid, and the current work is abandoned
					// Go back to the main loop to get the next work, and stuff
					// Returning to the main loop will clear work_restart, so use a flag...
					state->changework = true;
					return 0;
				case ICA_GETS_ERROR:
					do_icarus_close(thr);
					applog(LOG_ERR, "ICA%i: Comms error", icarus->device_id);
					dev_error(icarus, REASON_DEV_COMMS_ERROR);
					if (!icarus_reopen(icarus, state, &fd))
						return -1;
					break;
				case ICA_GETS_TIMEOUT:
					if (info->quirk_reopen == 1 && !icarus_reopen(icarus, state, &fd))
						return -1;
				case ICA_GETS_OK:
					break;
			}
		}

		tv_start = state->tv_workstart;
		timersub(&state->tv_workfinish, &tv_start, &elapsed);
	}
	else
	if (fd == -1 && !icarus_reopen(icarus, state, &fd))
		return -1;

#ifndef WIN32
	tcflush(fd, TCOFLUSH);
#endif

	memcpy(&nonce, nonce_bin, sizeof(nonce_bin));
	nonce = be32toh(nonce);

	// Handle dynamic clocking for "subclass" devices
	// This needs to run before sending next job, since it hashes the command too
	if (info->dclk.freqM && likely(!was_first_run)) {
		int qsec = ((4 * elapsed.tv_sec) + (elapsed.tv_usec / 250000)) ?: 1;
		for (int n = qsec; n; --n)
			dclk_gotNonces(&info->dclk);
		if (nonce && !test_nonce(&state->last_work, nonce, false))
			dclk_errorCount(&info->dclk, qsec);
		dclk_preUpdate(&info->dclk);
		dclk_updateFreq(&info->dclk, info->dclk_change_clock_func, thr);
	}

	if (!icarus_start_work(thr, ob_bin))
		/* This should never happen */
		state->firstrun = true;

	if (info->quirk_reopen == 2 && !icarus_reopen(icarus, state, &fd))
		state->firstrun = true;

	work->blk.nonce = 0xffffffff;

	if (was_first_run) {
		state->firstrun = false;
		__copy_work(&state->last_work, work);
		return 0;
	}

	// OK, done starting Icarus's next job... now process the last run's result!

	// aborted before becoming idle, get new work
	if (ret == ICA_GETS_TIMEOUT || ret == ICA_GETS_RESTART) {
		__copy_work(&state->last_work, work);
		// ONLY up to just when it aborted
		// We didn't read a reply so we don't subtract ICARUS_READ_TIME
		estimate_hashes = ((double)(elapsed.tv_sec)
					+ ((double)(elapsed.tv_usec))/((double)1000000)) / info->Hs;

		// If some Serial-USB delay allowed the full nonce range to
		// complete it can't have done more than a full nonce
		if (unlikely(estimate_hashes > 0xffffffff))
			estimate_hashes = 0xffffffff;

		if (opt_debug) {
			applog(LOG_DEBUG, "%"PRIpreprv" no nonce = 0x%08"PRIx64" hashes (%"PRId64".%06lus)",
					icarus->proc_repr,
					(uint64_t)estimate_hashes,
					(int64_t)elapsed.tv_sec, (unsigned long)elapsed.tv_usec);
		}

		return estimate_hashes;
	}

	curr_hw_errors = icarus->hw_errors;
	submit_nonce(thr, &state->last_work, nonce);
	was_hw_error = (curr_hw_errors > icarus->hw_errors);
	__copy_work(&state->last_work, work);

	// Force a USB close/reopen on any hw error
	if (was_hw_error)
		if (info->quirk_reopen != 2) {
			if (!icarus_reopen(icarus, state, &fd))
				state->firstrun = true;
			// Some devices (Cairnsmore1, for example) abort hashing when reopened, so send the job again
			if (!icarus_start_work(thr, ob_bin))
				state->firstrun = true;
		}

	hash_count = (nonce & info->nonce_mask);
	hash_count++;
	hash_count *= info->fpga_count;

	if (opt_debug) {
		applog(LOG_DEBUG, "%"PRIpreprv" nonce = 0x%08x = 0x%08" PRIx64 " hashes (%"PRId64".%06lus)",
				icarus->proc_repr,
				nonce,
				(uint64_t)hash_count,
				(int64_t)elapsed.tv_sec, (unsigned long)elapsed.tv_usec);
	}

	if (info->do_default_detection && elapsed.tv_sec >= DEFAULT_DETECT_THRESHOLD) {
		int MHs = (double)hash_count / ((double)elapsed.tv_sec * 1e6 + (double)elapsed.tv_usec);
		--info->do_default_detection;
		applog(LOG_DEBUG, "%"PRIpreprv": Autodetect device speed: %d MH/s", icarus->proc_repr, MHs);
		if (MHs <= 370 || MHs > 420) {
			// Not a real Icarus: enable short timing
			applog(LOG_WARNING, "%"PRIpreprv": Seems too %s to be an Icarus; calibrating with short timing", icarus->proc_repr, MHs>380?"fast":"slow");
			info->timing_mode = MODE_SHORT;
			info->do_icarus_timing = true;
			info->do_default_detection = 0;
		}
		else
		if (MHs <= 380) {
			// Real Icarus?
			if (!info->do_default_detection) {
				applog(LOG_DEBUG, "%"PRIpreprv": Seems to be a real Icarus", icarus->proc_repr);
				info->read_count = (int)(info->fullnonce * TIME_FACTOR) - 1;
			}
		}
		else
		if (MHs <= 420) {
			// Enterpoint Cairnsmore1
			size_t old_repr_len = strlen(icarus->proc_repr);
			char old_repr[old_repr_len + 1];
			strcpy(old_repr, icarus->proc_repr);
			convert_icarus_to_cairnsmore(icarus);
			info->do_default_detection = 0;
			applog(LOG_WARNING, "%"PRIpreprv": Detected Cairnsmore1 device, upgrading driver to %"PRIpreprv, old_repr, icarus->proc_repr);
		}
	}

	// ignore possible end condition values ... and hw errors
	if (info->do_icarus_timing
	&&  !was_hw_error
	&&  ((nonce & info->nonce_mask) > END_CONDITION)
	&&  ((nonce & info->nonce_mask) < (info->nonce_mask & ~END_CONDITION))) {
		gettimeofday(&tv_history_start, NULL);

		history0 = &(info->history[0]);

		if (history0->values == 0)
			timeradd(&tv_start, &history_sec, &(history0->finish));

		Ti = (double)(elapsed.tv_sec)
			+ ((double)(elapsed.tv_usec))/((double)1000000)
			- ((double)ICARUS_READ_TIME(info->baud));
		Xi = (double)hash_count;
		history0->sumXiTi += Xi * Ti;
		history0->sumXi += Xi;
		history0->sumTi += Ti;
		history0->sumXi2 += Xi * Xi;

		history0->values++;

		if (history0->hash_count_max < hash_count)
			history0->hash_count_max = hash_count;
		if (history0->hash_count_min > hash_count || history0->hash_count_min == 0)
			history0->hash_count_min = hash_count;

		if (history0->values >= info->min_data_count
		&&  timercmp(&tv_start, &(history0->finish), >)) {
			for (i = INFO_HISTORY; i > 0; i--)
				memcpy(&(info->history[i]),
					&(info->history[i-1]),
					sizeof(struct ICARUS_HISTORY));

			// Initialise history0 to zero for summary calculation
			memset(history0, 0, sizeof(struct ICARUS_HISTORY));

			// We just completed a history data set
			// So now recalc read_count based on the whole history thus we will
			// initially get more accurate until it completes INFO_HISTORY
			// total data sets
			count = 0;
			for (i = 1 ; i <= INFO_HISTORY; i++) {
				history = &(info->history[i]);
				if (history->values >= MIN_DATA_COUNT) {
					count++;

					history0->sumXiTi += history->sumXiTi;
					history0->sumXi += history->sumXi;
					history0->sumTi += history->sumTi;
					history0->sumXi2 += history->sumXi2;
					history0->values += history->values;

					if (history0->hash_count_max < history->hash_count_max)
						history0->hash_count_max = history->hash_count_max;
					if (history0->hash_count_min > history->hash_count_min || history0->hash_count_min == 0)
						history0->hash_count_min = history->hash_count_min;
				}
			}

			// All history data
			Hs = (history0->values*history0->sumXiTi - history0->sumXi*history0->sumTi)
				/ (history0->values*history0->sumXi2 - history0->sumXi*history0->sumXi);
			W = history0->sumTi/history0->values - Hs*history0->sumXi/history0->values;
			hash_count_range = history0->hash_count_max - history0->hash_count_min;
			values = history0->values;
			
			// Initialise history0 to zero for next data set
			memset(history0, 0, sizeof(struct ICARUS_HISTORY));

			fullnonce = W + Hs * (((double)0xffffffff) + 1);
			read_count = (int)(fullnonce * TIME_FACTOR) - 1;

			info->Hs = Hs;
			info->read_count = read_count;

			info->fullnonce = fullnonce;
			info->count = count;
			info->W = W;
			info->values = values;
			info->hash_count_range = hash_count_range;

			if (info->min_data_count < MAX_MIN_DATA_COUNT)
				info->min_data_count *= 2;
			else if (info->timing_mode == MODE_SHORT)
				info->do_icarus_timing = false;

//			applog(LOG_DEBUG, "%"PRIpreprv" Re-estimate: read_count=%d fullnonce=%fs history count=%d Hs=%e W=%e values=%d hash range=0x%08lx min data count=%u", icarus->proc_repr, read_count, fullnonce, count, Hs, W, values, hash_count_range, info->min_data_count);
			applog(LOG_DEBUG, "%"PRIpreprv" Re-estimate: Hs=%e W=%e read_count=%d fullnonce=%.3fs",
					icarus->proc_repr,
					Hs, W, read_count, fullnonce);
		}
		info->history_count++;
		gettimeofday(&tv_history_finish, NULL);

		timersub(&tv_history_finish, &tv_history_start, &tv_history_finish);
		timeradd(&tv_history_finish, &(info->history_time), &(info->history_time));
	}

	return hash_count;
}

static struct api_data *icarus_api_stats(struct cgpu_info *cgpu)
{
	struct api_data *root = NULL;
	struct ICARUS_INFO *info = cgpu->cgpu_data;

	// Warning, access to these is not locked - but we don't really
	// care since hashing performance is way more important than
	// locking access to displaying API debug 'stats'
	// If locking becomes an issue for any of them, use copy_data=true also
	root = api_add_int(root, "read_count", &(info->read_count), false);
	root = api_add_double(root, "fullnonce", &(info->fullnonce), false);
	root = api_add_int(root, "count", &(info->count), false);
	root = api_add_hs(root, "Hs", &(info->Hs), false);
	root = api_add_double(root, "W", &(info->W), false);
	root = api_add_uint(root, "total_values", &(info->values), false);
	root = api_add_uint64(root, "range", &(info->hash_count_range), false);
	root = api_add_uint64(root, "history_count", &(info->history_count), false);
	root = api_add_timeval(root, "history_time", &(info->history_time), false);
	root = api_add_uint(root, "min_data_count", &(info->min_data_count), false);
	root = api_add_uint(root, "timing_values", &(info->history[0].values), false);
	root = api_add_const(root, "timing_mode", timing_mode_str(info->timing_mode), false);
	root = api_add_bool(root, "is_timing", &(info->do_icarus_timing), false);
	root = api_add_int(root, "baud", &(info->baud), false);
	root = api_add_int(root, "work_division", &(info->work_division), false);
	root = api_add_int(root, "fpga_count", &(info->fpga_count), false);

	return root;
}

static void icarus_shutdown(struct thr_info *thr)
{
	do_icarus_close(thr);
	free(thr->cgpu_data);
}

struct device_api icarus_api = {
	.dname = "icarus",
	.name = "ICA",
	.api_detect = icarus_detect,
	.get_api_stats = icarus_api_stats,
	.thread_prepare = icarus_prepare,
	.scanhash = icarus_scanhash,
	.thread_shutdown = icarus_shutdown,
};