bfgminer/driver-bitforce.c

/*
 * Copyright 2012 Andrew Smith
 * Copyright 2012 Luke Dashjr
 * Copyright 2012 Con Kolivas
 *
 * 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.
 */

#include <limits.h>
#include <pthread.h>
#include <stdint.h>
#include <stdio.h>
#include <strings.h>
#include <sys/time.h>
#include <unistd.h>

#include "config.h"

#ifdef WIN32
#include <windows.h>
#endif /* WIN32 */

#include "compat.h"
#include "miner.h"
#include "usbutils.h"

#define BITFORCE_IDENTIFY "ZGX"
#define BITFORCE_IDENTIFY_LEN (sizeof(BITFORCE_IDENTIFY)-1)
#define BITFORCE_FLASH "ZMX"
#define BITFORCE_FLASH_LEN (sizeof(BITFORCE_FLASH)-1)
#define BITFORCE_TEMPERATURE "ZLX"
#define BITFORCE_TEMPERATURE_LEN (sizeof(BITFORCE_TEMPERATURE)-1)
#define BITFORCE_SENDRANGE "ZPX"
#define BITFORCE_SENDRANGE_LEN (sizeof(BITFORCE_SENDRANGE)-1)
#define BITFORCE_SENDWORK "ZDX"
#define BITFORCE_SENDWORK_LEN (sizeof(BITFORCE_SENDWORK)-1)
#define BITFORCE_WORKSTATUS "ZFX"
#define BITFORCE_WORKSTATUS_LEN (sizeof(BITFORCE_WORKSTATUS)-1)

#define BITFORCE_SLEEP_MS 500
#define BITFORCE_TIMEOUT_S 7
#define BITFORCE_TIMEOUT_MS (BITFORCE_TIMEOUT_S * 1000)
#define BITFORCE_LONG_TIMEOUT_S 30
#define BITFORCE_LONG_TIMEOUT_MS (BITFORCE_LONG_TIMEOUT_S * 1000)
#define BITFORCE_CHECK_INTERVAL_MS 10
#define WORK_CHECK_INTERVAL_MS 50
#define MAX_START_DELAY_MS 100
#define tv_to_ms(tval) (tval.tv_sec * 1000 + tval.tv_usec / 1000)
#define TIME_AVG_CONSTANT 8

#define KNAME_WORK  "full work"
#define KNAME_RANGE "nonce range"

#define BITFORCE_BUFSIZ (0x200)

// If initialisation fails the first time,
// sleep this amount (ms) and try again
#define REINIT_TIME_MS 1000
// But try this many times
#define REINIT_COUNT 6

static const char *blank = "";

struct device_drv bitforce_drv;

static void bitforce_initialise(struct cgpu_info *bitforce, bool lock)
{
	int err;

	if (lock)
		mutex_lock(&bitforce->device_mutex);

	// Reset
	err = usb_transfer(bitforce, FTDI_TYPE_OUT, FTDI_REQUEST_RESET,
				FTDI_VALUE_RESET, bitforce->usbdev->found->interface, C_RESET);
	if (opt_debug)
		applog(LOG_DEBUG, "%s%i: reset got err %d",
			bitforce->drv->name, bitforce->device_id, err);

	// Set data control
	err = usb_transfer(bitforce, FTDI_TYPE_OUT, FTDI_REQUEST_DATA,
				FTDI_VALUE_DATA, bitforce->usbdev->found->interface, C_SETDATA);
	if (opt_debug)
		applog(LOG_DEBUG, "%s%i: setdata got err %d",
			bitforce->drv->name, bitforce->device_id, err);

	// Set the baud
	err = usb_transfer(bitforce, FTDI_TYPE_OUT, FTDI_REQUEST_BAUD, FTDI_VALUE_BAUD,
				(FTDI_INDEX_BAUD & 0xff00) | bitforce->usbdev->found->interface,
				C_SETBAUD);
	if (opt_debug)
		applog(LOG_DEBUG, "%s%i: setbaud got err %d",
			bitforce->drv->name, bitforce->device_id, err);

	// Set Flow Control
	err = usb_transfer(bitforce, FTDI_TYPE_OUT, FTDI_REQUEST_FLOW,
				FTDI_VALUE_FLOW, bitforce->usbdev->found->interface, C_SETFLOW);
	if (opt_debug)
		applog(LOG_DEBUG, "%s%i: setflowctrl got err %d",
			bitforce->drv->name, bitforce->device_id, err);

	// Set Modem Control
	err = usb_transfer(bitforce, FTDI_TYPE_OUT, FTDI_REQUEST_MODEM,
				FTDI_VALUE_MODEM, bitforce->usbdev->found->interface, C_SETMODEM);
	if (opt_debug)
		applog(LOG_DEBUG, "%s%i: setmodemctrl got err %d",
			bitforce->drv->name, bitforce->device_id, err);

	// Clear any sent data
	err = usb_transfer(bitforce, FTDI_TYPE_OUT, FTDI_REQUEST_RESET,
				FTDI_VALUE_PURGE_TX, bitforce->usbdev->found->interface, C_PURGETX);
	if (opt_debug)
		applog(LOG_DEBUG, "%s%i: purgetx got err %d",
			bitforce->drv->name, bitforce->device_id, err);

	// Clear any received data
	err = usb_transfer(bitforce, FTDI_TYPE_OUT, FTDI_REQUEST_RESET,
				FTDI_VALUE_PURGE_RX, bitforce->usbdev->found->interface, C_PURGERX);
	if (opt_debug)
		applog(LOG_DEBUG, "%s%i: purgerx got err %d",
			bitforce->drv->name, bitforce->device_id, err);

	if (lock)
		mutex_unlock(&bitforce->device_mutex);
}

static bool bitforce_detect_one(struct libusb_device *dev, struct usb_find_devices *found)
{
	char buf[BITFORCE_BUFSIZ+1];
	char devpath[20];
	int err, amount;
	char *s;

	struct cgpu_info *bitforce = NULL;
	bitforce = calloc(1, sizeof(*bitforce));
	bitforce->drv = &bitforce_drv;
	bitforce->deven = DEV_ENABLED;
	bitforce->threads = 1;

	if (!usb_init(bitforce, dev, found)) {
		applog(LOG_ERR, "%s detect (%d:%d) failed to initialise (incorrect device?)",
			bitforce->drv->dname,
			(int)libusb_get_bus_number(dev),
			(int)libusb_get_device_address(dev));
		goto shin;
	}

	sprintf(devpath, "%d:%d",
			(int)(bitforce->usbdev->bus_number),
			(int)(bitforce->usbdev->device_address));

	int init_count = 0;
reinit:

	bitforce_initialise(bitforce, false);

	if ((err = usb_write(bitforce, BITFORCE_IDENTIFY, BITFORCE_IDENTIFY_LEN, &amount, C_REQUESTIDENTIFY)) < 0 || amount != BITFORCE_IDENTIFY_LEN) {
		applog(LOG_ERR, "%s detect (%s) send identify request failed (%d:%d)",
			bitforce->drv->dname, devpath, amount, err);
		goto unshin;
	}

	if ((err = usb_ftdi_read_nl(bitforce, buf, sizeof(buf)-1, &amount, C_GETIDENTIFY)) < 0 || amount < 1) {
		// Maybe it was still processing previous work?
		if (++init_count <= REINIT_COUNT) {
			if (init_count < 2) {
				applog(LOG_WARNING, "%s detect (%s) 1st init failed - retrying (%d:%d)",
					bitforce->drv->dname, devpath, amount, err);
			}
			nmsleep(REINIT_TIME_MS);
			goto reinit;
		}

		if (init_count > 0)
			applog(LOG_WARNING, "%s detect (%s) init failed %d times",
				bitforce->drv->dname, devpath, init_count);

		if (err < 0) {
			applog(LOG_ERR, "%s detect (%s) error identify reply (%d:%d)",
				bitforce->drv->dname, devpath, amount, err);
		} else {
			applog(LOG_ERR, "%s detect (%s) empty identify reply (%d)",
				bitforce->drv->dname, devpath, amount);
		}

		goto unshin;
	}
	buf[amount] = '\0';

	if (unlikely(!strstr(buf, "SHA256"))) {
		applog(LOG_ERR, "%s detect (%s) didn't recognise '%s'",
			bitforce->drv->dname, devpath, buf);
		goto unshin;
	}

	if (likely((!memcmp(buf, ">>>ID: ", 7)) && (s = strstr(buf + 3, ">>>")))) {
		s[0] = '\0';
		bitforce->name = strdup(buf + 7);
	} else {
		bitforce->name = (char *)blank;
	}

	// We have a real BitForce!
	applog(LOG_DEBUG, "%s (%s) identified as: '%s'",
		bitforce->drv->dname, devpath, bitforce->name);

	/* Initially enable support for nonce range and disable it later if it
	 * fails */
	if (opt_bfl_noncerange) {
		bitforce->nonce_range = true;
		bitforce->sleep_ms = BITFORCE_SLEEP_MS;
		bitforce->kname = KNAME_RANGE;
	} else {
		bitforce->sleep_ms = BITFORCE_SLEEP_MS * 5;
		bitforce->kname = KNAME_WORK;
	}

	bitforce->device_path = strdup(devpath);

	if (!add_cgpu(bitforce))
		goto unshin;

	update_usb_stats(bitforce);

	mutex_init(&bitforce->device_mutex);

	return true;

unshin:

	usb_uninit(bitforce);

shin:

	free(bitforce->device_path);

	if (bitforce->name != blank)
		free(bitforce->name);

	free(bitforce);

	return false;
}

static void bitforce_detect(void)
{
	usb_detect(&bitforce_drv, bitforce_detect_one);
}

static void get_bitforce_statline_before(char *buf, struct cgpu_info *bitforce)
{
	float gt = bitforce->temp;

	if (gt > 0)
		tailsprintf(buf, "%5.1fC ", gt);
	else
		tailsprintf(buf, "       ", gt);
	tailsprintf(buf, "        | ");
}

static bool bitforce_thread_prepare(struct thr_info *thr)
{
	struct cgpu_info *bitforce = thr->cgpu;
	struct timeval now;

	gettimeofday(&now, NULL);
	get_datestamp(bitforce->init, &now);

	return true;
}

static void bitforce_flash_led(struct cgpu_info *bitforce)
{
	int err, amount;

	/* Do not try to flash the led if we're polling for a result to
	 * minimise the chance of interleaved results */
	if (bitforce->polling)
		return;

	/* It is not critical flashing the led so don't get stuck if we
	 * can't grab the mutex now */
	if (mutex_trylock(&bitforce->device_mutex))
		return;

	if ((err = usb_write(bitforce, BITFORCE_FLASH, BITFORCE_FLASH_LEN, &amount, C_REQUESTFLASH)) < 0 || amount != BITFORCE_FLASH_LEN) {
		applog(LOG_ERR, "%s%i: flash request failed (%d:%d)",
			bitforce->drv->name, bitforce->device_id, amount, err);
	} else {
		/* However, this stops anything else getting a reply
		 * So best to delay any other access to the BFL */
		sleep(4);
	}

	/* Once we've tried - don't do it until told to again */
	bitforce->flash_led = false;

	mutex_unlock(&bitforce->device_mutex);

	return; // nothing is returned by the BFL
}

static bool bitforce_get_temp(struct cgpu_info *bitforce)
{
	char buf[BITFORCE_BUFSIZ+1];
	int err, amount;
	char *s;

	/* Do not try to get the temperature if we're polling for a result to
	 * minimise the chance of interleaved results */
	if (bitforce->polling)
		return true;

	// Flash instead of Temp - doing both can be too slow
	if (bitforce->flash_led) {
		bitforce_flash_led(bitforce);
 		return true;
	}

	/* It is not critical getting temperature so don't get stuck if we
	 * can't grab the mutex here */
	if (mutex_trylock(&bitforce->device_mutex))
		return false;

	if ((err = usb_write(bitforce, BITFORCE_TEMPERATURE, BITFORCE_TEMPERATURE_LEN, &amount, C_REQUESTTEMPERATURE)) < 0 || amount != BITFORCE_TEMPERATURE_LEN) {
		mutex_unlock(&bitforce->device_mutex);
		applog(LOG_ERR, "%s%i: Error: Request temp invalid/timed out (%d:%d)",
				bitforce->drv->name, bitforce->device_id, amount, err);
		bitforce->hw_errors++;
		return false;
	}

	if ((err = usb_ftdi_read_nl(bitforce, buf, sizeof(buf)-1, &amount, C_GETTEMPERATURE)) < 0 || amount < 1) {
		mutex_unlock(&bitforce->device_mutex);
		if (err < 0) {
			applog(LOG_ERR, "%s%i: Error: Get temp return invalid/timed out (%d:%d)",
					bitforce->drv->name, bitforce->device_id, amount, err);
		} else {
			applog(LOG_ERR, "%s%i: Error: Get temp returned nothing (%d:%d)",
					bitforce->drv->name, bitforce->device_id, amount, err);
		}
		bitforce->hw_errors++;
		return false;
	}

	mutex_unlock(&bitforce->device_mutex);
	
	if ((!strncasecmp(buf, "TEMP", 4)) && (s = strchr(buf + 4, ':'))) {
		float temp = strtof(s + 1, NULL);

		/* Cope with older software  that breaks and reads nonsense
		 * values */
		if (temp > 100)
			temp = strtod(s + 1, NULL);

		if (temp > 0) {
			bitforce->temp = temp;
			if (unlikely(bitforce->cutofftemp > 0 && temp > bitforce->cutofftemp)) {
				applog(LOG_WARNING, "%s%i: Hit thermal cutoff limit, disabling!",
							bitforce->drv->name, bitforce->device_id);
				bitforce->deven = DEV_RECOVER;
				dev_error(bitforce, REASON_DEV_THERMAL_CUTOFF);
			}
		}
	} else {
		/* Use the temperature monitor as a kind of watchdog for when
		 * our responses are out of sync and flush the buffer to
		 * hopefully recover */
		applog(LOG_WARNING, "%s%i: Garbled response probably throttling, clearing buffer",
					bitforce->drv->name, bitforce->device_id);
		dev_error(bitforce, REASON_DEV_THROTTLE);
		/* Count throttling episodes as hardware errors */
		bitforce->hw_errors++;
		bitforce_initialise(bitforce, true);
		return false;
	}

	return true;
}

static bool bitforce_send_work(struct thr_info *thr, struct work *work)
{
	struct cgpu_info *bitforce = thr->cgpu;
	unsigned char ob[70];
	char buf[BITFORCE_BUFSIZ+1];
	int err, amount;
	char *s;
	char *cmd;
	int len;

re_send:
	if (bitforce->nonce_range) {
		cmd = BITFORCE_SENDRANGE;
		len = BITFORCE_SENDRANGE_LEN;
	} else {
		cmd = BITFORCE_SENDWORK;
		len = BITFORCE_SENDWORK_LEN;
	}

	mutex_lock(&bitforce->device_mutex);
	if ((err = usb_write(bitforce, cmd, len, &amount, C_REQUESTSENDWORK)) < 0 || amount != len) {
		mutex_unlock(&bitforce->device_mutex);
		applog(LOG_ERR, "%s%i: request send work failed (%d:%d)",
				bitforce->drv->name, bitforce->device_id, amount, err);
		return false;
	}

	if ((err = usb_ftdi_read_nl(bitforce, buf, sizeof(buf)-1, &amount, C_REQUESTSENDWORKSTATUS)) < 0) {
		mutex_unlock(&bitforce->device_mutex);
		applog(LOG_ERR, "%s%d: read request send work status failed (%d:%d)",
				bitforce->drv->name, bitforce->device_id, amount, err);
		return false;
	}

	if (amount == 0 || !buf[0] || !strncasecmp(buf, "B", 1)) {
		mutex_unlock(&bitforce->device_mutex);
		nmsleep(WORK_CHECK_INTERVAL_MS);
		goto re_send;
	} else if (unlikely(strncasecmp(buf, "OK", 2))) {
		mutex_unlock(&bitforce->device_mutex);
		if (bitforce->nonce_range) {
			applog(LOG_WARNING, "%s%i: Does not support nonce range, disabling",
						bitforce->drv->name, bitforce->device_id);
			bitforce->nonce_range = false;
			bitforce->sleep_ms *= 5;
			bitforce->kname = KNAME_WORK;
			goto re_send;
		}
		applog(LOG_ERR, "%s%i: Error: Send work reports: %s",
				bitforce->drv->name, bitforce->device_id, buf);
		return false;
	}

	sprintf((char *)ob, ">>>>>>>>");
	memcpy(ob + 8, work->midstate, 32);
	memcpy(ob + 8 + 32, work->data + 64, 12);
	if (!bitforce->nonce_range) {
		sprintf((char *)ob + 8 + 32 + 12, ">>>>>>>>");
		work->blk.nonce = bitforce->nonces = 0xffffffff;
		len = 60;
	} else {
		uint32_t *nonce;

		nonce = (uint32_t *)(ob + 8 + 32 + 12);
		*nonce = htobe32(work->blk.nonce);
		nonce = (uint32_t *)(ob + 8 + 32 + 12 + 4);
		/* Split work up into 1/5th nonce ranges */
		bitforce->nonces = 0x33333332;
		*nonce = htobe32(work->blk.nonce + bitforce->nonces);
		work->blk.nonce += bitforce->nonces + 1;
		sprintf((char *)ob + 8 + 32 + 12 + 8, ">>>>>>>>");
		len = 68;
	}

	if ((err = usb_write(bitforce, (char *)ob, len, &amount, C_SENDWORK)) < 0 || amount != len) {
		mutex_unlock(&bitforce->device_mutex);
		applog(LOG_ERR, "%s%i: send work failed (%d:%d)",
				bitforce->drv->name, bitforce->device_id, amount, err);
		return false;
	}

	if ((err = usb_ftdi_read_nl(bitforce, buf, sizeof(buf)-1, &amount, C_SENDWORKSTATUS)) < 0) {
		mutex_unlock(&bitforce->device_mutex);
		applog(LOG_ERR, "%s%d: read send work status failed (%d:%d)",
				bitforce->drv->name, bitforce->device_id, amount, err);
		return false;
	}

	mutex_unlock(&bitforce->device_mutex);

	if (opt_debug) {
		s = bin2hex(ob + 8, 44);
		applog(LOG_DEBUG, "%s%i: block data: %s",
				bitforce->drv->name, bitforce->device_id, s);
		free(s);
	}

	if (amount == 0 || !buf[0]) {
		applog(LOG_ERR, "%s%i: Error: Send block data returned empty string/timed out",
				bitforce->drv->name, bitforce->device_id);
		return false;
	}

	if (unlikely(strncasecmp(buf, "OK", 2))) {
		applog(LOG_ERR, "%s%i: Error: Send block data reports: %s",
				bitforce->drv->name, bitforce->device_id, buf);
		return false;
	}

	gettimeofday(&bitforce->work_start_tv, NULL);
	return true;
}

static int64_t bitforce_get_result(struct thr_info *thr, struct work *work)
{
	struct cgpu_info *bitforce = thr->cgpu;
	unsigned int delay_time_ms;
	struct timeval elapsed;
	struct timeval now;
	char buf[BITFORCE_BUFSIZ+1];
	int amount;
	char *pnoncebuf;
	uint32_t nonce;

	while (1) {
		if (unlikely(thr->work_restart))
			return 0;

		mutex_lock(&bitforce->device_mutex);
		usb_write(bitforce, BITFORCE_WORKSTATUS, BITFORCE_WORKSTATUS_LEN, &amount, C_REQUESTWORKSTATUS);
		usb_ftdi_read_nl(bitforce, buf, sizeof(buf)-1, &amount, C_GETWORKSTATUS);
		mutex_unlock(&bitforce->device_mutex);

		gettimeofday(&now, NULL);
		timersub(&now, &bitforce->work_start_tv, &elapsed);

		if (elapsed.tv_sec >= BITFORCE_LONG_TIMEOUT_S) {
			applog(LOG_ERR, "%s%i: took %dms - longer than %dms",
				bitforce->drv->name, bitforce->device_id,
				tv_to_ms(elapsed), BITFORCE_LONG_TIMEOUT_MS);
			return 0;
		}

		if (amount > 0 && buf[0] && strncasecmp(buf, "B", 1)) /* BFL does not respond during throttling */
			break;

		/* if BFL is throttling, no point checking so quickly */
		delay_time_ms = (buf[0] ? BITFORCE_CHECK_INTERVAL_MS : 2 * WORK_CHECK_INTERVAL_MS);
		nmsleep(delay_time_ms);
		bitforce->wait_ms += delay_time_ms;
	}

	if (elapsed.tv_sec > BITFORCE_TIMEOUT_S) {
		applog(LOG_ERR, "%s%i: took %dms - longer than %dms",
			bitforce->drv->name, bitforce->device_id,
			tv_to_ms(elapsed), BITFORCE_TIMEOUT_MS);
		dev_error(bitforce, REASON_DEV_OVER_HEAT);

		/* Only return if we got nothing after timeout - there still may be results */
		if (amount == 0)
			return 0;
	} else if (!strncasecmp(buf, "N", 1)) {/* Hashing complete (NONCE-FOUND or NO-NONCE) */
		/* Simple timing adjustment. Allow a few polls to cope with
		 * OS timer delays being variably reliable. wait_ms will
		 * always equal sleep_ms when we've waited greater than or
		 * equal to the result return time.*/
		delay_time_ms = bitforce->sleep_ms;

		if (bitforce->wait_ms > bitforce->sleep_ms + (WORK_CHECK_INTERVAL_MS * 2))
			bitforce->sleep_ms += (bitforce->wait_ms - bitforce->sleep_ms) / 2;
		else if (bitforce->wait_ms == bitforce->sleep_ms) {
			if (bitforce->sleep_ms > WORK_CHECK_INTERVAL_MS)
				bitforce->sleep_ms -= WORK_CHECK_INTERVAL_MS;
			else if (bitforce->sleep_ms > BITFORCE_CHECK_INTERVAL_MS)
				bitforce->sleep_ms -= BITFORCE_CHECK_INTERVAL_MS;
		}

		if (delay_time_ms != bitforce->sleep_ms)
			  applog(LOG_DEBUG, "%s%i: Wait time changed to: %d, waited %u",
					bitforce->drv->name, bitforce->device_id,
					bitforce->sleep_ms, bitforce->wait_ms);

		/* Work out the average time taken. Float for calculation, uint for display */
		bitforce->avg_wait_f += (tv_to_ms(elapsed) - bitforce->avg_wait_f) / TIME_AVG_CONSTANT;
		bitforce->avg_wait_d = (unsigned int) (bitforce->avg_wait_f + 0.5);
	}

	applog(LOG_DEBUG, "%s%i: waited %dms until %s",
			bitforce->drv->name, bitforce->device_id,
			bitforce->wait_ms, buf);
	if (!strncasecmp(&buf[2], "-", 1))
		return bitforce->nonces;   /* No valid nonce found */
	else if (!strncasecmp(buf, "I", 1))
		return 0;	/* Device idle */
	else if (strncasecmp(buf, "NONCE-FOUND", 11)) {
		bitforce->hw_errors++;
		applog(LOG_WARNING, "%s%i: Error: Get result reports: %s",
			bitforce->drv->name, bitforce->device_id, buf);
		bitforce_initialise(bitforce, true);
		return 0;
	}

	pnoncebuf = &buf[12];

	while (1) {
		hex2bin((void*)&nonce, pnoncebuf, 4);
#ifndef __BIG_ENDIAN__
		nonce = swab32(nonce);
#endif
		if (unlikely(bitforce->nonce_range && (nonce >= work->blk.nonce ||
			(work->blk.nonce > 0 && nonce < work->blk.nonce - bitforce->nonces - 1)))) {
				applog(LOG_WARNING, "%s%i: Disabling broken nonce range support",
					bitforce->drv->name, bitforce->device_id);
				bitforce->nonce_range = false;
				work->blk.nonce = 0xffffffff;
				bitforce->sleep_ms *= 5;
				bitforce->kname = KNAME_WORK;
		}
			
		submit_nonce(thr, work, nonce);
		if (strncmp(&pnoncebuf[8], ",", 1))
			break;
		pnoncebuf += 9;
	}

	return bitforce->nonces;
}

static void bitforce_shutdown(__maybe_unused struct thr_info *thr)
{
//	struct cgpu_info *bitforce = thr->cgpu;
}

static void biforce_thread_enable(struct thr_info *thr)
{
	struct cgpu_info *bitforce = thr->cgpu;

	bitforce_initialise(bitforce, true);
}

static int64_t bitforce_scanhash(struct thr_info *thr, struct work *work, int64_t __maybe_unused max_nonce)
{
	struct cgpu_info *bitforce = thr->cgpu;
	bool send_ret;
	int64_t ret;

	send_ret = bitforce_send_work(thr, work);

	if (!restart_wait(bitforce->sleep_ms))
		return 0;

	bitforce->wait_ms = bitforce->sleep_ms;

	if (send_ret) {
		bitforce->polling = true;
		ret = bitforce_get_result(thr, work);
		bitforce->polling = false;
	} else
		ret = -1;

	if (ret == -1) {
		ret = 0;
		applog(LOG_ERR, "%s%i: Comms error", bitforce->drv->name, bitforce->device_id);
		dev_error(bitforce, REASON_DEV_COMMS_ERROR);
		bitforce->hw_errors++;
		/* empty read buffer */
		bitforce_initialise(bitforce, true);
	}
	return ret;
}

static bool bitforce_get_stats(struct cgpu_info *bitforce)
{
	return bitforce_get_temp(bitforce);
}

static void bitforce_identify(struct cgpu_info *bitforce)
{
	bitforce->flash_led = true;
}

static bool bitforce_thread_init(struct thr_info *thr)
{
	struct cgpu_info *bitforce = thr->cgpu;
	unsigned int wait;

	/* Pause each new thread at least 100ms between initialising
	 * so the devices aren't making calls all at the same time. */
	wait = thr->id * MAX_START_DELAY_MS;
	applog(LOG_DEBUG, "%s%d: Delaying start by %dms",
			bitforce->drv->name, bitforce->device_id, wait / 1000);
	nmsleep(wait);

	return true;
}

static struct api_data *bitforce_api_stats(struct cgpu_info *cgpu)
{
	struct api_data *root = NULL;

	// 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_uint(root, "Sleep Time", &(cgpu->sleep_ms), false);
	root = api_add_uint(root, "Avg Wait", &(cgpu->avg_wait_d), false);

	return root;
}

struct device_drv bitforce_drv = {
	.drv = DRIVER_BITFORCE,
	.dname = "bitforce",
	.name = "BFL",
	.drv_detect = bitforce_detect,
	.get_api_stats = bitforce_api_stats,
	.get_statline_before = get_bitforce_statline_before,
	.get_stats = bitforce_get_stats,
	.identify_device = bitforce_identify,
	.thread_prepare = bitforce_thread_prepare,
	.thread_init = bitforce_thread_init,
	.scanhash = bitforce_scanhash,
	.thread_shutdown = bitforce_shutdown,
	.thread_enable = biforce_thread_enable
};