thodg/cgminer/driver-knc-spi-fpga.c

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• Hash : b542f523
  Author :
  Date : 2013-10-29T22:08:00
  

  Add copyright notice to knc driver.

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• driver-knc-spi-fpga.c

• /*
   * cgminer driver for KnCminer devices
   *
   * Copyright 2013 Con Kolivas <kernel@kolivas.org>
   * Copyright 2013 KnCminer
   *
   * 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 <stdlib.h>
  #include <assert.h>
  #include <fcntl.h>
  #include <limits.h>
  #include <unistd.h>
  #include <sys/ioctl.h>
  #include <linux/types.h>
  #include <linux/spi/spidev.h>
  
  #include "logging.h"
  #include "miner.h"
  
  #define MAX_SPIS		1
  #define	MAX_BYTES_IN_SPI_XSFER	4096
  /* /dev/spidevB.C, where B = bus, C = chipselect */
  #define SPI_DEVICE_TEMPLATE	"/dev/spidev%d.%d"
  #define SPI_MODE		(SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
  #define SPI_BITS_PER_WORD	32
  #define SPI_MAX_SPEED		3000000
  #define SPI_DELAY_USECS		0
  /* Max number of ASICs permitted on one SPI device */
  #define MAX_ASICS		6
  
  /* How many hardware errors in a row before disabling the core */
  #define HW_ERR_LIMIT		10
  #define DISA_ERR_LIMIT		3
  
  #define MAX_ACTIVE_WORKS	(192 * 2 * 6 * 2)
  
  #define WORK_MIDSTATE_WORDS	8
  #define WORK_DATA_WORDS		3
  
  #define WORK_STALE_US		60000000
  
  /* Keep core disabled for no longer than 15 minutes */
  #define CORE_DISA_PERIOD_US	(15 * 60 * 1000000)
  
  struct spidev_context {
  	int fd;
  	uint32_t speed;
  	uint16_t delay;
  	uint8_t mode;
  	uint8_t bits;
  };
  
  struct spi_request {
  #define	CMD_NOP		0
  #define	CMD_GET_VERSION	1
  #define	CMD_SUBMIT_WORK	2
  #define	CMD_FLUSH_QUEUE	3
  
  #define	WORK_ID_MASK	0x7FFF
  
  #if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
  	uint32_t cmd		:4;
  	uint32_t rsvd		:1; /* set to zero */
  	uint32_t queue_id	:12;
  	uint32_t work_id	:15;
  #else
  	uint32_t work_id	:15;
  	uint32_t queue_id	:12;
  	uint32_t rsvd		:1; /* set to zero */
  	uint32_t cmd		:4;
  #endif
  	uint32_t midstate[WORK_MIDSTATE_WORDS];
  	uint32_t data[WORK_DATA_WORDS];
  };
  
  struct spi_response {
  #define	RESPONSE_TYPE_NOP		0
  #define	RESPONSE_TYPE_NONCE_FOUND	1
  #define	RESPONSE_TYPE_WORK_DONE		2
  #if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
  	uint32_t type		:2;
  	uint32_t asic		:3;
  	uint32_t queue_id	:12;
  	uint32_t work_id	:15;
  #else
  	uint32_t work_id	:15;
  	uint32_t queue_id	:12;
  	uint32_t asic		:3;
  	uint32_t type		:2;
  #endif
  	uint32_t nonce;
  	uint32_t core;
  };
  
  #define MAX_REQUESTS_IN_BATCH	( MAX_BYTES_IN_SPI_XSFER /	\
  				  sizeof(struct spi_request)	\
  				)
  
  static struct spi_request spi_txbuf[MAX_REQUESTS_IN_BATCH];
  
  #define MAX_RESPONSES_IN_BATCH	( (sizeof(spi_txbuf) - 12) /	\
  				   sizeof(struct spi_response)	\
  				)
  
  struct spi_rx_t {
  #if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
  	uint32_t rsvd_1			:31;
  	uint32_t response_queue_full	:1;
  #else
  	uint32_t response_queue_full	:1;
  	uint32_t rsvd_1			:31;
  #endif
  #if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
  	uint32_t rsvd_2			:16;
  	uint32_t works_accepted		:16;
  #else
  	uint32_t works_accepted		:16;
  	uint32_t rsvd_2			:16;
  #endif
  	uint32_t rsvd_3;
  	struct spi_response responses[MAX_RESPONSES_IN_BATCH];
  };
  
  static struct spi_rx_t spi_rxbuf;
  
  struct active_work {
  	struct work *work;
  	uint32_t work_id;
  	struct timeval begin;
  };
  
  struct core_disa_data {
  	struct timeval disa_begin;
  	uint8_t asic;
  	uint8_t core;
  };
  
  struct knc_state {
  	struct spidev_context *ctx;
  	int devices;
  	uint32_t salt;
  	uint32_t next_work_id;
  
  	/* read - last read item, next is at (read + 1) mod BUFSIZE
  	 * write - next write item, last written at (write - 1) mod BUFSIZE
  	 *  When buffer is empty, read + 1 == write
  	 *  Buffer full condition: read == write
  	 */
  	int read_q, write_q;
  #define KNC_QUEUED_BUFFER_SIZE	(MAX_REQUESTS_IN_BATCH + 1)
  	struct active_work queued_fifo[KNC_QUEUED_BUFFER_SIZE];
  
  	int read_a, write_a;
  #define KNC_ACTIVE_BUFFER_SIZE	(MAX_ACTIVE_WORKS + 1)
  	struct active_work active_fifo[KNC_ACTIVE_BUFFER_SIZE];
  
  	uint8_t hwerrs[MAX_ASICS * 256];
  	uint8_t disa_cnt[MAX_ASICS * 256];
  	uint32_t hwerr_work_id[MAX_ASICS * 256];
  	int read_d, write_d;
  #define KNC_DISA_CORES_SIZE	(MAX_ASICS * 256)
  	struct core_disa_data disa_cores_fifo[KNC_DISA_CORES_SIZE];
  
  	pthread_mutex_t lock;
  };
  
  static inline bool knc_queued_fifo_full(struct knc_state *knc)
  {
  	return (knc->read_q == knc->write_q);
  }
  
  static inline bool knc_active_fifo_full(struct knc_state *knc)
  {
  	return (knc->read_a == knc->write_a);
  }
  
  static inline void knc_queued_fifo_inc_idx(int *idx)
  {
  	if (unlikely(*idx >= ((int)KNC_QUEUED_BUFFER_SIZE - 1)))
  		*idx = 0;
  	else
  		++(*idx);
  }
  
  static inline void knc_active_fifo_inc_idx(int *idx)
  {
  	if (unlikely(*idx >= (KNC_ACTIVE_BUFFER_SIZE - 1)))
  		*idx = 0;
  	else
  		++(*idx);
  }
  
  static inline void knc_disa_cores_fifo_inc_idx(int *idx)
  {
  	if (unlikely(*idx >= (KNC_DISA_CORES_SIZE - 1)))
  		*idx = 0;
  	else
  		++(*idx);
  }
  
  /* Find SPI device with index idx, init it */
  static struct spidev_context *spi_new(int idx)
  {
  	struct spidev_context *ctx;
  	char dev_fname[PATH_MAX];
  
  	if (NULL == (ctx = malloc(sizeof(struct spidev_context)))) {
  		applog(LOG_ERR, "KnC spi: Out of memory");
  		goto l_exit_error;
  	}
  	ctx->mode = SPI_MODE;
  	ctx->bits = SPI_BITS_PER_WORD;
  	ctx->speed = SPI_MAX_SPEED;
  	ctx->delay = SPI_DELAY_USECS;
  
  	ctx->fd = -1;
  
  	sprintf(dev_fname, SPI_DEVICE_TEMPLATE,
  		idx, /* bus */
  		0    /* chipselect */
  	       );
  	if (0 > (ctx->fd = open(dev_fname, O_RDWR))) {
  		applog(LOG_ERR, "KnC spi: Can not open SPI device %s: %m",
  		       dev_fname);
  		goto l_free_exit_error;
  	}
  
  	/*
  	 * spi mode
  	 */
  	if (0 > ioctl(ctx->fd, SPI_IOC_WR_MODE, &ctx->mode))
  		goto l_ioctl_error;
  	if (0 > ioctl(ctx->fd, SPI_IOC_RD_MODE, &ctx->mode))
  		goto l_ioctl_error;
  
  	/*
  	 * bits per word
  	 */
  	if (0 > ioctl(ctx->fd, SPI_IOC_WR_BITS_PER_WORD, &ctx->bits))
  		goto l_ioctl_error;
  	if (0 > ioctl(ctx->fd, SPI_IOC_RD_BITS_PER_WORD, &ctx->bits))
  		goto l_ioctl_error;
  
  	/*
  	 * max speed hz
  	 */
  	if (0 > ioctl(ctx->fd, SPI_IOC_WR_MAX_SPEED_HZ, &ctx->speed))
  		goto l_ioctl_error;
  	if (0 > ioctl(ctx->fd, SPI_IOC_RD_MAX_SPEED_HZ, &ctx->speed))
  		goto l_ioctl_error;
  
  	applog(LOG_INFO, "KnC spi: device %s uses mode %hhu, bits %hhu, speed %u",
  	       dev_fname, ctx->mode, ctx->bits, ctx->speed);
  
  	return ctx;
  
  l_ioctl_error:
  	applog(LOG_ERR, "KnC spi: ioctl error on SPI device %s: %m", dev_fname);
  	close(ctx->fd);
  l_free_exit_error:
  	free(ctx);
  l_exit_error:
  	return NULL;
  }
  
  static void spi_free(struct spidev_context *ctx)
  {
  	if (NULL == ctx)
  		return;
  
  	close(ctx->fd);
  	free(ctx);
  }
  
  static int spi_transfer(struct spidev_context *ctx, uint8_t *txbuf,
  			uint8_t *rxbuf, int len)
  {
  	struct spi_ioc_transfer xfr;
  	int ret;
  
  	memset(rxbuf, 0xff, len);
  
  	ret = len;
  
  	xfr.tx_buf = (unsigned long)txbuf;
  	xfr.rx_buf = (unsigned long)rxbuf;
  	xfr.len = len;
  	xfr.speed_hz = ctx->speed;
  	xfr.delay_usecs = ctx->delay;
  	xfr.bits_per_word = ctx->bits;
  	xfr.cs_change = 0;
  	xfr.pad = 0;
  
  	if (1 > (ret = ioctl(ctx->fd, SPI_IOC_MESSAGE(1), &xfr)))
  		applog(LOG_ERR, "KnC spi xfer: ioctl error on SPI device: %m");
  
  	return ret;
  }
  
  static void disable_core(uint8_t asic, uint8_t core)
  {
  	char str[256];
  
  	snprintf(str, sizeof(str), "i2cset -y 2 0x2%hhu %hhu 0", asic, core);
  	if (0 != WEXITSTATUS(system(str)))
  		applog(LOG_ERR, "KnC: system call failed");
  }
  
  static void enable_core(uint8_t asic, uint8_t core)
  {
  	char str[256];
  
  	snprintf(str, sizeof(str), "i2cset -y 2 0x2%hhu %hhu 1", asic, core);
  	if (0 != WEXITSTATUS(system(str)))
  		applog(LOG_ERR, "KnC: system call failed");
  }
  
  static int64_t timediff(const struct timeval *a, const struct timeval *b)
  {
  	struct timeval diff;
  
  	timersub(a, b, &diff);
  
  	return diff.tv_sec * 1000000 + diff.tv_usec;
  }
  
  static void knc_check_disabled_cores(struct knc_state *knc)
  {
  	struct core_disa_data *core;
  	int next_read_d, cidx;
  	struct timeval now;
  	int64_t us;
  
  	next_read_d = knc->read_d;
  	knc_disa_cores_fifo_inc_idx(&next_read_d);
  	if (next_read_d == knc->write_d)
  		return; /* queue empty */
  
  	core = &knc->disa_cores_fifo[next_read_d];
  	gettimeofday(&now, NULL);
  	us = timediff(&now, &core->disa_begin);
  	if ((us >= 0) && (us < CORE_DISA_PERIOD_US))
  		return; /* latest disabled core still not expired */
  
  	cidx = core->asic * 256 + core->core;
  	enable_core(core->asic, core->core);
  	knc->hwerrs[cidx] = 0;
  	applog(LOG_NOTICE,
  	       "KnC: core %u-%u was enabled back from disabled state",
  	       core->asic, core->core);
  	knc->read_d = next_read_d;
  }
  
  static void knc_work_from_queue_to_spi(struct knc_state *knc,
  				       struct active_work *q_work,
  				       struct spi_request *spi_req)
  {
  	uint32_t *buf_from, *buf_to;
  	int i;
  
  	spi_req->cmd = CMD_SUBMIT_WORK;
  	spi_req->queue_id = 0; /* at the moment we have one and only queue #0 */
  	spi_req->work_id = (knc->next_work_id ^ knc->salt) & WORK_ID_MASK;
  	q_work->work_id = spi_req->work_id;
  	++(knc->next_work_id);
  	buf_to = spi_req->midstate;
  	buf_from = (uint32_t *)q_work->work->midstate;
  
  	for (i = 0; i < WORK_MIDSTATE_WORDS; ++i)
  		buf_to[i] = le32toh(buf_from[8 - i - 1]);
  	buf_to = spi_req->data;
  	buf_from = (uint32_t *)&(q_work->work->data[16 * 4]);
  
  	for (i = 0; i < WORK_DATA_WORDS; ++i)
  		buf_to[i] = le32toh(buf_from[3 - i - 1]);
  }
  
  static int64_t knc_process_response(struct thr_info *thr, struct cgpu_info *cgpu,
  				    struct spi_rx_t *rxbuf)
  {
  	struct knc_state *knc = cgpu->device_data;
  	int submitted, successful, i, num_sent;
  	int next_read_q, next_read_a;
  	struct timeval now;
  	struct work *work;
  	int64_t us;
  
  	num_sent = knc->write_q - knc->read_q - 1;
  	if (knc->write_q <= knc->read_q)
  		num_sent += KNC_QUEUED_BUFFER_SIZE;
  
  	/* Actually process SPI response */
  	if (rxbuf->works_accepted) {
  		applog(LOG_DEBUG, "KnC spi: raw response %08X %08X",
  		       ((uint32_t *)rxbuf)[0], ((uint32_t *)rxbuf)[1]);
  		applog(LOG_DEBUG,
  		       "KnC spi: response, accepted %u (from %u), full %u",
  		       rxbuf->works_accepted, num_sent,
  		       rxbuf->response_queue_full);
  	}
  	/* move works_accepted number of items from queued_fifo to active_fifo */
  	gettimeofday(&now, NULL);
  	submitted = 0;
  
  	for (i = 0; i < rxbuf->works_accepted; ++i) {
  		next_read_q = knc->read_q;
  		knc_queued_fifo_inc_idx(&next_read_q);
  		if ((next_read_q == knc->write_q) || knc_active_fifo_full(knc))
  			break;
  
  		memcpy(&knc->active_fifo[knc->write_a],
  		       &knc->queued_fifo[next_read_q],
  		       sizeof(struct active_work));
  		knc->active_fifo[knc->write_a].begin = now;
  		knc->queued_fifo[next_read_q].work = NULL;
  		knc->read_q = next_read_q;
  		knc_active_fifo_inc_idx(&knc->write_a);
  		++submitted;
  	}
  	if (submitted != rxbuf->works_accepted) {
  		applog(LOG_ERR,
  		       "KnC: accepted by FPGA %u works, but only %d submitted",
  		       rxbuf->works_accepted, submitted);
  	}
  
  	/* check for completed works and calculated nonces */
  	gettimeofday(&now, NULL);
  	successful = 0;
  
  	for (i = 0; i < (int)MAX_RESPONSES_IN_BATCH; ++i) {
  		if ((rxbuf->responses[i].type != RESPONSE_TYPE_NONCE_FOUND) &&
  		    (rxbuf->responses[i].type != RESPONSE_TYPE_WORK_DONE))
  			continue;
  
  		applog(LOG_DEBUG, "KnC spi: raw response %08X %08X",
  		       ((uint32_t *)&rxbuf->responses[i])[0],
  		       ((uint32_t *)&rxbuf->responses[i])[1]);
  		applog(LOG_DEBUG, "KnC spi: response, T:%u C:%u-%u Q:%u W:%u",
  		       rxbuf->responses[i].type,
  		       rxbuf->responses[i].asic, rxbuf->responses[i].core,
  		       rxbuf->responses[i].queue_id,
  		       rxbuf->responses[i].work_id);
  		/* Find active work with matching ID */
  		next_read_a = knc->read_a;
  		knc_active_fifo_inc_idx(&next_read_a);
  
  		while (next_read_a != knc->write_a) {
  			if (knc->active_fifo[next_read_a].work_id ==
  			    rxbuf->responses[i].work_id)
  				break;
  
  			/* check for stale works */
  			us = timediff(&now,
  				      &knc->active_fifo[next_read_a].begin);
  			if ((us < 0) || (us >= WORK_STALE_US)) {
  				applog(LOG_DEBUG,
  				       "KnC spi: remove stale work %u",
  				       knc->active_fifo[next_read_a].work_id);
  				work = knc->active_fifo[next_read_a].work;
  				knc_active_fifo_inc_idx(&knc->read_a);
  				work_completed(cgpu, work);
  				if (next_read_a != knc->read_a) {
  					memcpy(&(knc->active_fifo[next_read_a]),
  					       &(knc->active_fifo[knc->read_a]),
  					       sizeof(struct active_work));
  				}
  				knc->active_fifo[knc->read_a].work = NULL;
  			}
  
  			knc_active_fifo_inc_idx(&next_read_a);
  		}
  		if (next_read_a == knc->write_a)
  			continue;
  
  		applog(LOG_DEBUG, "KnC spi: response work %u found",
  		       rxbuf->responses[i].work_id);
  		work = knc->active_fifo[next_read_a].work;
  
  		if (rxbuf->responses[i].type == RESPONSE_TYPE_NONCE_FOUND) {
  			if (NULL != thr) {
  				int cidx = rxbuf->responses[i].asic * 256 +
  					   rxbuf->responses[i].core;
  
  				if (submit_nonce(thr, work,
  						 rxbuf->responses[i].nonce)) {
  					if (cidx < (int)sizeof(knc->hwerrs)) {
  						knc->hwerrs[cidx] = 0;
  						knc->disa_cnt[cidx] = 0;
  						knc->hwerr_work_id[cidx] = 0xFFFFFFFF;
  					}
  					successful++;
  				} else  {
  					if ((cidx < (int)sizeof(knc->hwerrs)) &&
  					    (knc->hwerr_work_id[cidx] != rxbuf->responses[i].work_id)) {
  						knc->hwerr_work_id[cidx] = rxbuf->responses[i].work_id;
  						if (++(knc->hwerrs[cidx]) >= HW_ERR_LIMIT) {
  						    struct core_disa_data *core;
  
  						    core = &knc->disa_cores_fifo[knc->write_d];
  						    core->disa_begin = now;
  						    core->asic = rxbuf->responses[i].asic;
  						    core->core = rxbuf->responses[i].core;
  						    disable_core(core->asic, core->core);
  						    if (++(knc->disa_cnt[cidx]) >= DISA_ERR_LIMIT) {
  							    applog(LOG_WARNING,
  			"KnC: core %u-%u was disabled permanently", core->asic, core->core);
  						    } else {
  							    applog(LOG_WARNING,
  			"KnC: core %u-%u was disabled due to %u HW errors in a row",
  								   core->asic, core->core, HW_ERR_LIMIT);
  							    knc_disa_cores_fifo_inc_idx(&knc->write_d);
  						    }
  						}
  					}
  				};
  			}
  			continue;
  		}
  
  		/* Work completed */
  		knc_active_fifo_inc_idx(&knc->read_a);
  		work_completed(cgpu, work);
  		if (next_read_a != knc->read_a) {
  			memcpy(&(knc->active_fifo[next_read_a]),
  			       &(knc->active_fifo[knc->read_a]),
  			       sizeof(struct active_work));
  		}
  		knc->active_fifo[knc->read_a].work = NULL;
  	}
  
  	return ((uint64_t)successful) * 0x100000000UL;
  }
  
  /* Send flush command via SPI */
  static int _internal_knc_flush_fpga(struct knc_state *knc)
  {
  	int len;
  
  	spi_txbuf[0].cmd = CMD_FLUSH_QUEUE;
  	spi_txbuf[0].queue_id = 0; /* at the moment we have one and only queue #0 */
  	len = spi_transfer(knc->ctx, (uint8_t *)spi_txbuf,
  			   (uint8_t *)&spi_rxbuf, sizeof(struct spi_request));
  	if (len != sizeof(struct spi_request))
  		return -1;
  
  	len /= sizeof(struct spi_response);
  
  	return len;
  }
  
  static bool knc_detect_one(struct spidev_context *ctx)
  {
  	/* Scan device for ASICs */
  	int chip_id, devices = 0;
  	struct cgpu_info *cgpu;
  	struct knc_state *knc;
  
  	for (chip_id = 0; chip_id < MAX_ASICS; ++chip_id) {
  		/* TODO: perform the ASIC test/detection */
  		++devices;
  	}
  
  	if (!devices) {
  		applog(LOG_INFO, "SPI detected, but not KnCminer ASICs");
  		return false;
  	}
  
  	applog(LOG_INFO, "Found a KnC miner with %d ASICs", devices);
  
  	cgpu = calloc(1, sizeof(*cgpu));
  	knc = calloc(1, sizeof(*knc));
  	if (!cgpu || !knc) {
  		applog(LOG_ERR, "KnC miner detected, but failed to allocate memory");
  		return false;
  	}
  
  	knc->ctx = ctx;
  	knc->devices = devices;
  	knc->read_q = 0;
  	knc->write_q = 1;
  	knc->read_a = 0;
  	knc->write_a = 1;
  	knc->read_d = 0;
  	knc->write_d = 1;
  	knc->salt = rand();
  	mutex_init(&knc->lock);
  
  	memset(knc->hwerr_work_id, 0xFF, sizeof(knc->hwerr_work_id));
  
  	_internal_knc_flush_fpga(knc);
  
  	cgpu->drv = &knc_drv;
  	cgpu->name = "KnCminer";
  	cgpu->threads = 1;	// .. perhaps our number of devices?
  
  	cgpu->device_data = knc;
  	add_cgpu(cgpu);
  
  	return true;
  }
  
  // http://www.concentric.net/~Ttwang/tech/inthash.htm
  static unsigned long mix(unsigned long a, unsigned long b, unsigned long c)
  {
  	a = a - b;  a = a - c;  a = a ^ (c >> 13);
  	b = b - c;  b = b - a;  b = b ^ (a << 8);
  	c = c - a;  c = c - b;  c = c ^ (b >> 13);
  	a = a - b;  a = a - c;  a = a ^ (c >> 12);
  	b = b - c;  b = b - a;  b = b ^ (a << 16);
  	c = c - a;  c = c - b;  c = c ^ (b >> 5);
  	a = a - b;  a = a - c;  a = a ^ (c >> 3);
  	b = b - c;  b = b - a;  b = b ^ (a << 10);
  	c = c - a;  c = c - b;  c = c ^ (b >> 15);
  
  	return c;
  }
  
  /* Probe devices and register with add_cgpu */
  void knc_detect(bool __maybe_unused hotplug)
  {
  	int idx;
  
  	srand(mix(clock(), time(NULL), getpid()));
  
  	/* Loop through all possible SPI interfaces */
  	for (idx = 0; idx < MAX_SPIS; ++idx) {
  		struct spidev_context *ctx = spi_new(idx + 1);
  
  		if (ctx != NULL) {
  			if (!knc_detect_one(ctx))
  				spi_free(ctx);
  		}
  	}
  }
  
  /* return value is number of nonces that have been checked since
   * previous call
   */
  static int64_t knc_scanwork(struct thr_info *thr)
  {
  	struct cgpu_info *cgpu = thr->cgpu;
  	struct knc_state *knc = cgpu->device_data;
  	int len, num, next_read_q;
  	int64_t ret;
  
  	applog(LOG_DEBUG, "KnC running scanwork");
  
  	knc_check_disabled_cores(knc);
  
  	/* Prepare tx buffer */
  	memset(spi_txbuf, 0, sizeof(spi_txbuf));
  	num = 0;
  
  	mutex_lock(&knc->lock);
  	next_read_q = knc->read_q;
  	knc_queued_fifo_inc_idx(&next_read_q);
  
  	while (next_read_q != knc->write_q) {
  		knc_work_from_queue_to_spi(knc, &knc->queued_fifo[next_read_q],
  					   &spi_txbuf[num]);
  		knc_queued_fifo_inc_idx(&next_read_q);
  		++num;
  	}
  	/* knc->read_q is advanced in knc_process_response, not here */
  
  	len = spi_transfer(knc->ctx, (uint8_t *)spi_txbuf,
  			   (uint8_t *)&spi_rxbuf, sizeof(spi_txbuf));
  	if (len != sizeof(spi_rxbuf)) {
  		ret = -1;
  		goto out_unlock;
  	}
  
  	applog(LOG_DEBUG, "KnC spi: %d works in request", num);
  
  	ret = knc_process_response(thr, cgpu, &spi_rxbuf);
  out_unlock:
  	mutex_unlock(&knc->lock);
  
  	return ret;
  }
  
  static bool knc_queue_full(struct cgpu_info *cgpu)
  {
  	struct knc_state *knc = cgpu->device_data;
  	int queue_full = false;
  	struct work *work;
  
  	applog(LOG_DEBUG, "KnC running queue full");
  
  	mutex_lock(&knc->lock);
  	if (knc_queued_fifo_full(knc)) {
  		queue_full = true;
  		goto out_unlock;
  	}
  	work = get_queued(cgpu);
  	if (!work)
  		goto out_unlock;
  	knc->queued_fifo[knc->write_q].work = work;
  	knc_queued_fifo_inc_idx(&(knc->write_q));
  	if (knc_queued_fifo_full(knc))
  		queue_full = true;
  out_unlock:
  	mutex_unlock(&knc->lock);
  
  	return queue_full;
  }
  
  static void knc_flush_work(struct cgpu_info *cgpu)
  {
  	struct knc_state *knc = cgpu->device_data;
  	int len, next_read_q, next_read_a;
  	struct work *work;
  
  	applog(LOG_ERR, "KnC running flushwork");
  
  	mutex_lock(&knc->lock);
  	/* Drain queued works */
  	next_read_q = knc->read_q;
  	knc_queued_fifo_inc_idx(&next_read_q);
  
  	while (next_read_q != knc->write_q) {
  		work = knc->queued_fifo[next_read_q].work;
  		work_completed(cgpu, work);
  		knc->queued_fifo[next_read_q].work = NULL;
  		knc->read_q = next_read_q;
  		knc_queued_fifo_inc_idx(&next_read_q);
  	}
  
  	/* Drain active works */
  	next_read_a = knc->read_a;
  	knc_active_fifo_inc_idx(&next_read_a);
  
  	while (next_read_a != knc->write_a) {
  		work = knc->active_fifo[next_read_a].work;
  		work_completed(cgpu, work);
  		knc->active_fifo[next_read_a].work = NULL;
  		knc->read_a = next_read_a;
  		knc_active_fifo_inc_idx(&next_read_a);
  	}
  
  	len = _internal_knc_flush_fpga(knc);
  	if (len > 0)
  		knc_process_response(NULL, cgpu, &spi_rxbuf);
  	mutex_unlock(&knc->lock);
  }
  
  struct device_drv knc_drv = {
  	.drv_id = DRIVER_knc,
  	.dname = "KnCminer",
  	.name = "KnC",
  	.drv_detect = knc_detect,	// Probe for devices, add with add_cgpu
  
  	.hash_work = hash_queued_work,
  	.scanwork = knc_scanwork,
  	.queue_full = knc_queue_full,
  	.flush_work = knc_flush_work,
  };
  

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