drivers/staging/greybus/spilib.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Greybus SPI library
  *
  * Copyright 2014-2016 Google Inc.
  * Copyright 2014-2016 Linaro Ltd.
  */

 #include <linux/bitops.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/greybus.h>
 #include <linux/spi/spi.h>

 #include "spilib.h"

 struct gb_spilib {
 	struct gb_connection	*connection;
 	struct device		*parent;
 	struct spi_transfer	*first_xfer;
 	struct spi_transfer	*last_xfer;
 	struct spilib_ops	*ops;
 	u32			rx_xfer_offset;
 	u32			tx_xfer_offset;
 	u32			last_xfer_size;
 	unsigned int		op_timeout;
 	u16			mode;
 	u16			flags;
 	u32			bits_per_word_mask;
 	u8			num_chipselect;
 	u32			min_speed_hz;
 	u32			max_speed_hz;
 };

 #define GB_SPI_STATE_MSG_DONE		((void *)0)
 #define GB_SPI_STATE_MSG_IDLE		((void *)1)
 #define GB_SPI_STATE_MSG_RUNNING	((void *)2)
 #define GB_SPI_STATE_OP_READY		((void *)3)
 #define GB_SPI_STATE_OP_DONE		((void *)4)
 #define GB_SPI_STATE_MSG_ERROR		((void *)-1)

 #define XFER_TIMEOUT_TOLERANCE		200

 static struct spi_master *get_master_from_spi(struct gb_spilib *spi)
 {
 	return gb_connection_get_data(spi->connection);
 }

 static int tx_header_fit_operation(u32 tx_size, u32 count, size_t data_max)
 {
 	size_t headers_size;

 	data_max -= sizeof(struct gb_spi_transfer_request);
 	headers_size = (count + 1) * sizeof(struct gb_spi_transfer);

 	return tx_size + headers_size > data_max ? 0 : 1;
 }

 static size_t calc_rx_xfer_size(u32 rx_size, u32 *tx_xfer_size, u32 len,
 				size_t data_max)
 {
 	size_t rx_xfer_size;

 	data_max -= sizeof(struct gb_spi_transfer_response);

 	if (rx_size + len > data_max)
 		rx_xfer_size = data_max - rx_size;
 	else
 		rx_xfer_size = len;

 	/* if this is a write_read, for symmetry read the same as write */
 	if (*tx_xfer_size && rx_xfer_size > *tx_xfer_size)
 		rx_xfer_size = *tx_xfer_size;
 	if (*tx_xfer_size && rx_xfer_size < *tx_xfer_size)
 		*tx_xfer_size = rx_xfer_size;

 	return rx_xfer_size;
 }

 static size_t calc_tx_xfer_size(u32 tx_size, u32 count, size_t len,
 				size_t data_max)
 {
 	size_t headers_size;

 	data_max -= sizeof(struct gb_spi_transfer_request);
 	headers_size = (count + 1) * sizeof(struct gb_spi_transfer);

 	if (tx_size + headers_size + len > data_max)
 		return data_max - (tx_size + sizeof(struct gb_spi_transfer));

 	return len;
 }

 static void clean_xfer_state(struct gb_spilib *spi)
 {
 	spi->first_xfer = NULL;
 	spi->last_xfer = NULL;
 	spi->rx_xfer_offset = 0;
 	spi->tx_xfer_offset = 0;
 	spi->last_xfer_size = 0;
 	spi->op_timeout = 0;
 }

 static bool is_last_xfer_done(struct gb_spilib *spi)
 {
 	struct spi_transfer *last_xfer = spi->last_xfer;

 	if ((spi->tx_xfer_offset + spi->last_xfer_size == last_xfer->len) ||
 	    (spi->rx_xfer_offset + spi->last_xfer_size == last_xfer->len))
 		return true;

 	return false;
 }

 static int setup_next_xfer(struct gb_spilib *spi, struct spi_message *msg)
 {
 	struct spi_transfer *last_xfer = spi->last_xfer;

 	if (msg->state != GB_SPI_STATE_OP_DONE)
 		return 0;

 	/*
 	 * if we transferred all content of the last transfer, reset values and
 	 * check if this was the last transfer in the message
 	 */
 	if (is_last_xfer_done(spi)) {
 		spi->tx_xfer_offset = 0;
 		spi->rx_xfer_offset = 0;
 		spi->op_timeout = 0;
 		if (last_xfer == list_last_entry(&msg->transfers,
 						 struct spi_transfer,
 						 transfer_list))
 			msg->state = GB_SPI_STATE_MSG_DONE;
 		else
 			spi->first_xfer = list_next_entry(last_xfer,
 							  transfer_list);
 		return 0;
 	}

 	spi->first_xfer = last_xfer;
 	if (last_xfer->tx_buf)
 		spi->tx_xfer_offset += spi->last_xfer_size;

 	if (last_xfer->rx_buf)
 		spi->rx_xfer_offset += spi->last_xfer_size;

 	return 0;
 }

 static struct spi_transfer *get_next_xfer(struct spi_transfer *xfer,
 					  struct spi_message *msg)
 {
 	if (xfer == list_last_entry(&msg->transfers, struct spi_transfer,
 				    transfer_list))
 		return NULL;

 	return list_next_entry(xfer, transfer_list);
 }

 /* Routines to transfer data */
 static struct gb_operation *gb_spi_operation_create(struct gb_spilib *spi,
 		struct gb_connection *connection, struct spi_message *msg)
 {
 	struct gb_spi_transfer_request *request;
 	struct spi_device *dev = msg->spi;
 	struct spi_transfer *xfer;
 	struct gb_spi_transfer *gb_xfer;
 	struct gb_operation *operation;
 	u32 tx_size = 0, rx_size = 0, count = 0, xfer_len = 0, request_size;
 	u32 tx_xfer_size = 0, rx_xfer_size = 0, len;
 	u32 total_len = 0;
 	unsigned int xfer_timeout;
 	size_t data_max;
 	void *tx_data;

 	data_max = gb_operation_get_payload_size_max(connection);
 	xfer = spi->first_xfer;

 	/* Find number of transfers queued and tx/rx length in the message */

 	while (msg->state != GB_SPI_STATE_OP_READY) {
 		msg->state = GB_SPI_STATE_MSG_RUNNING;
 		spi->last_xfer = xfer;

 		if (!xfer->tx_buf && !xfer->rx_buf) {
 			dev_err(spi->parent,
 				"bufferless transfer, length %u\n", xfer->len);
 			msg->state = GB_SPI_STATE_MSG_ERROR;
 			return NULL;
 		}

 		tx_xfer_size = 0;
 		rx_xfer_size = 0;

 		if (xfer->tx_buf) {
 			len = xfer->len - spi->tx_xfer_offset;
 			if (!tx_header_fit_operation(tx_size, count, data_max))
 				break;
 			tx_xfer_size = calc_tx_xfer_size(tx_size, count,
 							 len, data_max);
 			spi->last_xfer_size = tx_xfer_size;
 		}

 		if (xfer->rx_buf) {
 			len = xfer->len - spi->rx_xfer_offset;
 			rx_xfer_size = calc_rx_xfer_size(rx_size, &tx_xfer_size,
 							 len, data_max);
 			spi->last_xfer_size = rx_xfer_size;
 		}

 		tx_size += tx_xfer_size;
 		rx_size += rx_xfer_size;

 		total_len += spi->last_xfer_size;
 		count++;

 		xfer = get_next_xfer(xfer, msg);
 		if (!xfer || total_len >= data_max)
 			msg->state = GB_SPI_STATE_OP_READY;
 	}

 	/*
 	 * In addition to space for all message descriptors we need
 	 * to have enough to hold all tx data.
 	 */
 	request_size = sizeof(*request);
 	request_size += count * sizeof(*gb_xfer);
 	request_size += tx_size;

 	/* Response consists only of incoming data */
 	operation = gb_operation_create(connection, GB_SPI_TYPE_TRANSFER,
 					request_size, rx_size, GFP_KERNEL);
 	if (!operation)
 		return NULL;

 	request = operation->request->payload;
 	request->count = cpu_to_le16(count);
 	request->mode = dev->mode;
 	request->chip_select = spi_get_chipselect(dev, 0);

 	gb_xfer = &request->transfers[0];
 	tx_data = gb_xfer + count;	/* place tx data after last gb_xfer */

 	/* Fill in the transfers array */
 	xfer = spi->first_xfer;
 	while (msg->state != GB_SPI_STATE_OP_DONE) {
 		int xfer_delay;

 		if (xfer == spi->last_xfer)
 			xfer_len = spi->last_xfer_size;
 		else
 			xfer_len = xfer->len;

 		/* make sure we do not timeout in a slow transfer */
 		xfer_timeout = xfer_len * 8 * MSEC_PER_SEC / xfer->speed_hz;
 		xfer_timeout += GB_OPERATION_TIMEOUT_DEFAULT;

 		if (xfer_timeout > spi->op_timeout)
 			spi->op_timeout = xfer_timeout;

 		gb_xfer->speed_hz = cpu_to_le32(xfer->speed_hz);
 		gb_xfer->len = cpu_to_le32(xfer_len);
 		xfer_delay = spi_delay_to_ns(&xfer->delay, xfer) / 1000;
 		xfer_delay = clamp_t(u16, xfer_delay, 0, U16_MAX);
 		gb_xfer->delay_usecs = cpu_to_le16(xfer_delay);
 		gb_xfer->cs_change = xfer->cs_change;
 		gb_xfer->bits_per_word = xfer->bits_per_word;

 		/* Copy tx data */
 		if (xfer->tx_buf) {
 			gb_xfer->xfer_flags |= GB_SPI_XFER_WRITE;
 			memcpy(tx_data, xfer->tx_buf + spi->tx_xfer_offset,
 			       xfer_len);
 			tx_data += xfer_len;
 		}

 		if (xfer->rx_buf)
 			gb_xfer->xfer_flags |= GB_SPI_XFER_READ;

 		if (xfer == spi->last_xfer) {
 			if (!is_last_xfer_done(spi))
 				gb_xfer->xfer_flags |= GB_SPI_XFER_INPROGRESS;
 			msg->state = GB_SPI_STATE_OP_DONE;
 			continue;
 		}

 		gb_xfer++;
 		xfer = get_next_xfer(xfer, msg);
 	}

 	msg->actual_length += total_len;

 	return operation;
 }

 static void gb_spi_decode_response(struct gb_spilib *spi,
 				   struct spi_message *msg,
 				   struct gb_spi_transfer_response *response)
 {
 	struct spi_transfer *xfer = spi->first_xfer;
 	void *rx_data = response->data;
 	u32 xfer_len;

 	while (xfer) {
 		/* Copy rx data */
 		if (xfer->rx_buf) {
 			if (xfer == spi->first_xfer)
 				xfer_len = xfer->len - spi->rx_xfer_offset;
 			else if (xfer == spi->last_xfer)
 				xfer_len = spi->last_xfer_size;
 			else
 				xfer_len = xfer->len;

 			memcpy(xfer->rx_buf + spi->rx_xfer_offset, rx_data,
 			       xfer_len);
 			rx_data += xfer_len;
 		}

 		if (xfer == spi->last_xfer)
 			break;

 		xfer = list_next_entry(xfer, transfer_list);
 	}
 }

 static int gb_spi_transfer_one_message(struct spi_master *master,
 				       struct spi_message *msg)
 {
 	struct gb_spilib *spi = spi_master_get_devdata(master);
 	struct gb_connection *connection = spi->connection;
 	struct gb_spi_transfer_response *response;
 	struct gb_operation *operation;
 	int ret = 0;

 	spi->first_xfer = list_first_entry_or_null(&msg->transfers,
 						   struct spi_transfer,
 						   transfer_list);
 	if (!spi->first_xfer) {
 		ret = -ENOMEM;
 		goto out;
 	}

 	msg->state = GB_SPI_STATE_MSG_IDLE;

 	while (msg->state != GB_SPI_STATE_MSG_DONE &&
 	       msg->state != GB_SPI_STATE_MSG_ERROR) {
 		operation = gb_spi_operation_create(spi, connection, msg);
 		if (!operation) {
 			msg->state = GB_SPI_STATE_MSG_ERROR;
 			ret = -EINVAL;
 			continue;
 		}

 		ret = gb_operation_request_send_sync_timeout(operation,
 							     spi->op_timeout);
 		if (!ret) {
 			response = operation->response->payload;
 			if (response)
 				gb_spi_decode_response(spi, msg, response);
 		} else {
 			dev_err(spi->parent,
 				"transfer operation failed: %d\n", ret);
 			msg->state = GB_SPI_STATE_MSG_ERROR;
 		}

 		gb_operation_put(operation);
 		setup_next_xfer(spi, msg);
 	}

 out:
 	msg->status = ret;
 	clean_xfer_state(spi);
 	spi_finalize_current_message(master);

 	return ret;
 }

 static int gb_spi_prepare_transfer_hardware(struct spi_master *master)
 {
 	struct gb_spilib *spi = spi_master_get_devdata(master);

 	return spi->ops->prepare_transfer_hardware(spi->parent);
 }

 static int gb_spi_unprepare_transfer_hardware(struct spi_master *master)
 {
 	struct gb_spilib *spi = spi_master_get_devdata(master);

 	spi->ops->unprepare_transfer_hardware(spi->parent);

 	return 0;
 }

 static int gb_spi_setup(struct spi_device *spi)
 {
 	/* Nothing to do for now */
 	return 0;
 }

 static void gb_spi_cleanup(struct spi_device *spi)
 {
 	/* Nothing to do for now */
 }

 /* Routines to get controller information */

 /*
  * Map Greybus spi mode bits/flags/bpw into Linux ones.
  * All bits are same for now and so these macro's return same values.
  */
 #define gb_spi_mode_map(mode) mode
 #define gb_spi_flags_map(flags) flags

 static int gb_spi_get_master_config(struct gb_spilib *spi)
 {
 	struct gb_spi_master_config_response response;
 	u16 mode, flags;
 	int ret;

 	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_MASTER_CONFIG,
 				NULL, 0, &response, sizeof(response));
 	if (ret < 0)
 		return ret;

 	mode = le16_to_cpu(response.mode);
 	spi->mode = gb_spi_mode_map(mode);

 	flags = le16_to_cpu(response.flags);
 	spi->flags = gb_spi_flags_map(flags);

 	spi->bits_per_word_mask = le32_to_cpu(response.bits_per_word_mask);
 	spi->num_chipselect = response.num_chipselect;

 	spi->min_speed_hz = le32_to_cpu(response.min_speed_hz);
 	spi->max_speed_hz = le32_to_cpu(response.max_speed_hz);

 	return 0;
 }

 static int gb_spi_setup_device(struct gb_spilib *spi, u8 cs)
 {
 	struct spi_master *master = get_master_from_spi(spi);
 	struct gb_spi_device_config_request request;
 	struct gb_spi_device_config_response response;
 	struct spi_board_info spi_board = { {0} };
 	struct spi_device *spidev;
 	int ret;
 	u8 dev_type;

 	request.chip_select = cs;

 	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_DEVICE_CONFIG,
 				&request, sizeof(request),
 				&response, sizeof(response));
 	if (ret < 0)
 		return ret;

 	dev_type = response.device_type;

 	if (dev_type == GB_SPI_SPI_DEV)
 		strscpy(spi_board.modalias, "spidev",
 			sizeof(spi_board.modalias));
 	else if (dev_type == GB_SPI_SPI_NOR)
 		strscpy(spi_board.modalias, "spi-nor",
 			sizeof(spi_board.modalias));
 	else if (dev_type == GB_SPI_SPI_MODALIAS)
 		memcpy(spi_board.modalias, response.name,
 		       sizeof(spi_board.modalias));
 	else
 		return -EINVAL;

 	spi_board.mode		= le16_to_cpu(response.mode);
 	spi_board.bus_num	= master->bus_num;
 	spi_board.chip_select	= cs;
 	spi_board.max_speed_hz	= le32_to_cpu(response.max_speed_hz);

 	spidev = spi_new_device(master, &spi_board);
 	if (!spidev)
 		return -EINVAL;

 	return 0;
 }

 int gb_spilib_master_init(struct gb_connection *connection, struct device *dev,
 			  struct spilib_ops *ops)
 {
 	struct gb_spilib *spi;
 	struct spi_master *master;
 	int ret;
 	u8 i;

 	/* Allocate master with space for data */
 	master = spi_alloc_master(dev, sizeof(*spi));
 	if (!master) {
 		dev_err(dev, "cannot alloc SPI master\n");
 		return -ENOMEM;
 	}

 	spi = spi_master_get_devdata(master);
 	spi->connection = connection;
 	gb_connection_set_data(connection, master);
 	spi->parent = dev;
 	spi->ops = ops;

 	/* get master configuration */
 	ret = gb_spi_get_master_config(spi);
 	if (ret)
 		goto exit_spi_put;

 	master->bus_num = -1; /* Allow spi-core to allocate it dynamically */
 	master->num_chipselect = spi->num_chipselect;
 	master->mode_bits = spi->mode;
 	master->flags = spi->flags;
 	master->bits_per_word_mask = spi->bits_per_word_mask;

 	/* Attach methods */
 	master->cleanup = gb_spi_cleanup;
 	master->setup = gb_spi_setup;
 	master->transfer_one_message = gb_spi_transfer_one_message;

 	if (ops && ops->prepare_transfer_hardware) {
 		master->prepare_transfer_hardware =
 			gb_spi_prepare_transfer_hardware;
 	}

 	if (ops && ops->unprepare_transfer_hardware) {
 		master->unprepare_transfer_hardware =
 			gb_spi_unprepare_transfer_hardware;
 	}

 	master->auto_runtime_pm = true;

 	ret = spi_register_master(master);
 	if (ret < 0)
 		goto exit_spi_put;

 	/* now, fetch the devices configuration */
 	for (i = 0; i < spi->num_chipselect; i++) {
 		ret = gb_spi_setup_device(spi, i);
 		if (ret < 0) {
 			dev_err(dev, "failed to allocate spi device %d: %d\n",
 				i, ret);
 			goto exit_spi_unregister;
 		}
 	}

 	return 0;

 exit_spi_put:
 	spi_master_put(master);

 	return ret;

 exit_spi_unregister:
 	spi_unregister_master(master);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(gb_spilib_master_init);

 void gb_spilib_master_exit(struct gb_connection *connection)
 {
 	struct spi_master *master = gb_connection_get_data(connection);

 	spi_unregister_master(master);
 }
 EXPORT_SYMBOL_GPL(gb_spilib_master_exit);

 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Greybus SPI library
	*
	* Copyright 2014-2016 Google Inc.
	* Copyright 2014-2016 Linaro Ltd.
	*/

	#include <linux/bitops.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/greybus.h>
	#include <linux/spi/spi.h>

	#include "spilib.h"

	struct gb_spilib {
	struct gb_connection *connection;
	struct device *parent;
	struct spi_transfer *first_xfer;
	struct spi_transfer *last_xfer;
	struct spilib_ops *ops;
	u32 rx_xfer_offset;
	u32 tx_xfer_offset;
	u32 last_xfer_size;
	unsigned int op_timeout;
	u16 mode;
	u16 flags;
	u32 bits_per_word_mask;
	u8 num_chipselect;
	u32 min_speed_hz;
	u32 max_speed_hz;
	};

	#define GB_SPI_STATE_MSG_DONE ((void *)0)
	#define GB_SPI_STATE_MSG_IDLE ((void *)1)
	#define GB_SPI_STATE_MSG_RUNNING ((void *)2)
	#define GB_SPI_STATE_OP_READY ((void *)3)
	#define GB_SPI_STATE_OP_DONE ((void *)4)
	#define GB_SPI_STATE_MSG_ERROR ((void *)-1)

	#define XFER_TIMEOUT_TOLERANCE 200

	static struct spi_master get_master_from_spi(struct gb_spilib spi)
	{
	return gb_connection_get_data(spi->connection);
	}

	static int tx_header_fit_operation(u32 tx_size, u32 count, size_t data_max)
	{
	size_t headers_size;

	data_max -= sizeof(struct gb_spi_transfer_request);
	headers_size = (count + 1) * sizeof(struct gb_spi_transfer);

	return tx_size + headers_size > data_max ? 0 : 1;
	}

	static size_t calc_rx_xfer_size(u32 rx_size, u32 *tx_xfer_size, u32 len,
	size_t data_max)
	{
	size_t rx_xfer_size;

	data_max -= sizeof(struct gb_spi_transfer_response);

	if (rx_size + len > data_max)
	rx_xfer_size = data_max - rx_size;
	else
	rx_xfer_size = len;

	/* if this is a write_read, for symmetry read the same as write */
	if (tx_xfer_size && rx_xfer_size > tx_xfer_size)
	rx_xfer_size = *tx_xfer_size;
	if (tx_xfer_size && rx_xfer_size < tx_xfer_size)
	*tx_xfer_size = rx_xfer_size;

	return rx_xfer_size;
	}

	static size_t calc_tx_xfer_size(u32 tx_size, u32 count, size_t len,
	size_t data_max)
	{
	size_t headers_size;

	data_max -= sizeof(struct gb_spi_transfer_request);
	headers_size = (count + 1) * sizeof(struct gb_spi_transfer);

	if (tx_size + headers_size + len > data_max)
	return data_max - (tx_size + sizeof(struct gb_spi_transfer));

	return len;
	}

	static void clean_xfer_state(struct gb_spilib *spi)
	{
	spi->first_xfer = NULL;
	spi->last_xfer = NULL;
	spi->rx_xfer_offset = 0;
	spi->tx_xfer_offset = 0;
	spi->last_xfer_size = 0;
	spi->op_timeout = 0;
	}

	static bool is_last_xfer_done(struct gb_spilib *spi)
	{
	struct spi_transfer *last_xfer = spi->last_xfer;

	if ((spi->tx_xfer_offset + spi->last_xfer_size == last_xfer->len) \|\|
	(spi->rx_xfer_offset + spi->last_xfer_size == last_xfer->len))
	return true;

	return false;
	}

	static int setup_next_xfer(struct gb_spilib spi, struct spi_message msg)
	{
	struct spi_transfer *last_xfer = spi->last_xfer;

	if (msg->state != GB_SPI_STATE_OP_DONE)
	return 0;

	/*
	* if we transferred all content of the last transfer, reset values and
	* check if this was the last transfer in the message
	*/
	if (is_last_xfer_done(spi)) {
	spi->tx_xfer_offset = 0;
	spi->rx_xfer_offset = 0;
	spi->op_timeout = 0;
	if (last_xfer == list_last_entry(&msg->transfers,
	struct spi_transfer,
	transfer_list))
	msg->state = GB_SPI_STATE_MSG_DONE;
	else
	spi->first_xfer = list_next_entry(last_xfer,
	transfer_list);
	return 0;
	}

	spi->first_xfer = last_xfer;
	if (last_xfer->tx_buf)
	spi->tx_xfer_offset += spi->last_xfer_size;

	if (last_xfer->rx_buf)
	spi->rx_xfer_offset += spi->last_xfer_size;

	return 0;
	}

	static struct spi_transfer get_next_xfer(struct spi_transfer xfer,
	struct spi_message *msg)
	{
	if (xfer == list_last_entry(&msg->transfers, struct spi_transfer,
	transfer_list))
	return NULL;

	return list_next_entry(xfer, transfer_list);
	}

	/* Routines to transfer data */
	static struct gb_operation gb_spi_operation_create(struct gb_spilib spi,
	struct gb_connection connection, struct spi_message msg)
	{
	struct gb_spi_transfer_request *request;
	struct spi_device *dev = msg->spi;
	struct spi_transfer *xfer;
	struct gb_spi_transfer *gb_xfer;
	struct gb_operation *operation;
	u32 tx_size = 0, rx_size = 0, count = 0, xfer_len = 0, request_size;
	u32 tx_xfer_size = 0, rx_xfer_size = 0, len;
	u32 total_len = 0;
	unsigned int xfer_timeout;
	size_t data_max;
	void *tx_data;

	data_max = gb_operation_get_payload_size_max(connection);
	xfer = spi->first_xfer;

	/* Find number of transfers queued and tx/rx length in the message */

	while (msg->state != GB_SPI_STATE_OP_READY) {
	msg->state = GB_SPI_STATE_MSG_RUNNING;
	spi->last_xfer = xfer;

	if (!xfer->tx_buf && !xfer->rx_buf) {
	dev_err(spi->parent,
	"bufferless transfer, length %u\n", xfer->len);
	msg->state = GB_SPI_STATE_MSG_ERROR;
	return NULL;
	}

	tx_xfer_size = 0;
	rx_xfer_size = 0;

	if (xfer->tx_buf) {
	len = xfer->len - spi->tx_xfer_offset;
	if (!tx_header_fit_operation(tx_size, count, data_max))
	break;
	tx_xfer_size = calc_tx_xfer_size(tx_size, count,
	len, data_max);
	spi->last_xfer_size = tx_xfer_size;
	}

	if (xfer->rx_buf) {
	len = xfer->len - spi->rx_xfer_offset;
	rx_xfer_size = calc_rx_xfer_size(rx_size, &tx_xfer_size,
	len, data_max);
	spi->last_xfer_size = rx_xfer_size;
	}

	tx_size += tx_xfer_size;
	rx_size += rx_xfer_size;

	total_len += spi->last_xfer_size;
	count++;

	xfer = get_next_xfer(xfer, msg);
	if (!xfer \|\| total_len >= data_max)
	msg->state = GB_SPI_STATE_OP_READY;
	}

	/*
	* In addition to space for all message descriptors we need
	* to have enough to hold all tx data.
	*/
	request_size = sizeof(*request);
	request_size += count * sizeof(*gb_xfer);
	request_size += tx_size;

	/* Response consists only of incoming data */
	operation = gb_operation_create(connection, GB_SPI_TYPE_TRANSFER,
	request_size, rx_size, GFP_KERNEL);
	if (!operation)
	return NULL;

	request = operation->request->payload;
	request->count = cpu_to_le16(count);
	request->mode = dev->mode;
	request->chip_select = spi_get_chipselect(dev, 0);

	gb_xfer = &request->transfers[0];
	tx_data = gb_xfer + count; /* place tx data after last gb_xfer */

	/* Fill in the transfers array */
	xfer = spi->first_xfer;
	while (msg->state != GB_SPI_STATE_OP_DONE) {
	int xfer_delay;

	if (xfer == spi->last_xfer)
	xfer_len = spi->last_xfer_size;
	else
	xfer_len = xfer->len;

	/* make sure we do not timeout in a slow transfer */
	xfer_timeout = xfer_len * 8 * MSEC_PER_SEC / xfer->speed_hz;
	xfer_timeout += GB_OPERATION_TIMEOUT_DEFAULT;

	if (xfer_timeout > spi->op_timeout)
	spi->op_timeout = xfer_timeout;

	gb_xfer->speed_hz = cpu_to_le32(xfer->speed_hz);
	gb_xfer->len = cpu_to_le32(xfer_len);
	xfer_delay = spi_delay_to_ns(&xfer->delay, xfer) / 1000;
	xfer_delay = clamp_t(u16, xfer_delay, 0, U16_MAX);
	gb_xfer->delay_usecs = cpu_to_le16(xfer_delay);
	gb_xfer->cs_change = xfer->cs_change;
	gb_xfer->bits_per_word = xfer->bits_per_word;

	/* Copy tx data */
	if (xfer->tx_buf) {
	gb_xfer->xfer_flags \|= GB_SPI_XFER_WRITE;
	memcpy(tx_data, xfer->tx_buf + spi->tx_xfer_offset,
	xfer_len);
	tx_data += xfer_len;
	}

	if (xfer->rx_buf)
	gb_xfer->xfer_flags \|= GB_SPI_XFER_READ;

	if (xfer == spi->last_xfer) {
	if (!is_last_xfer_done(spi))
	gb_xfer->xfer_flags \|= GB_SPI_XFER_INPROGRESS;
	msg->state = GB_SPI_STATE_OP_DONE;
	continue;
	}

	gb_xfer++;
	xfer = get_next_xfer(xfer, msg);
	}

	msg->actual_length += total_len;

	return operation;
	}

	static void gb_spi_decode_response(struct gb_spilib *spi,
	struct spi_message *msg,
	struct gb_spi_transfer_response *response)
	{
	struct spi_transfer *xfer = spi->first_xfer;
	void *rx_data = response->data;
	u32 xfer_len;

	while (xfer) {
	/* Copy rx data */
	if (xfer->rx_buf) {
	if (xfer == spi->first_xfer)
	xfer_len = xfer->len - spi->rx_xfer_offset;
	else if (xfer == spi->last_xfer)
	xfer_len = spi->last_xfer_size;
	else
	xfer_len = xfer->len;

	memcpy(xfer->rx_buf + spi->rx_xfer_offset, rx_data,
	xfer_len);
	rx_data += xfer_len;
	}

	if (xfer == spi->last_xfer)
	break;

	xfer = list_next_entry(xfer, transfer_list);
	}
	}

	static int gb_spi_transfer_one_message(struct spi_master *master,
	struct spi_message *msg)
	{
	struct gb_spilib *spi = spi_master_get_devdata(master);
	struct gb_connection *connection = spi->connection;
	struct gb_spi_transfer_response *response;
	struct gb_operation *operation;
	int ret = 0;

	spi->first_xfer = list_first_entry_or_null(&msg->transfers,
	struct spi_transfer,
	transfer_list);
	if (!spi->first_xfer) {
	ret = -ENOMEM;
	goto out;
	}

	msg->state = GB_SPI_STATE_MSG_IDLE;

	while (msg->state != GB_SPI_STATE_MSG_DONE &&
	msg->state != GB_SPI_STATE_MSG_ERROR) {
	operation = gb_spi_operation_create(spi, connection, msg);
	if (!operation) {
	msg->state = GB_SPI_STATE_MSG_ERROR;
	ret = -EINVAL;
	continue;
	}

	ret = gb_operation_request_send_sync_timeout(operation,
	spi->op_timeout);
	if (!ret) {
	response = operation->response->payload;
	if (response)
	gb_spi_decode_response(spi, msg, response);
	} else {
	dev_err(spi->parent,
	"transfer operation failed: %d\n", ret);
	msg->state = GB_SPI_STATE_MSG_ERROR;
	}

	gb_operation_put(operation);
	setup_next_xfer(spi, msg);
	}

	out:
	msg->status = ret;
	clean_xfer_state(spi);
	spi_finalize_current_message(master);

	return ret;
	}

	static int gb_spi_prepare_transfer_hardware(struct spi_master *master)
	{
	struct gb_spilib *spi = spi_master_get_devdata(master);

	return spi->ops->prepare_transfer_hardware(spi->parent);
	}

	static int gb_spi_unprepare_transfer_hardware(struct spi_master *master)
	{
	struct gb_spilib *spi = spi_master_get_devdata(master);

	spi->ops->unprepare_transfer_hardware(spi->parent);

	return 0;
	}

	static int gb_spi_setup(struct spi_device *spi)
	{
	/* Nothing to do for now */
	return 0;
	}

	static void gb_spi_cleanup(struct spi_device *spi)
	{
	/* Nothing to do for now */
	}

	/* Routines to get controller information */

	/*
	* Map Greybus spi mode bits/flags/bpw into Linux ones.
	* All bits are same for now and so these macro's return same values.
	*/
	#define gb_spi_mode_map(mode) mode
	#define gb_spi_flags_map(flags) flags

	static int gb_spi_get_master_config(struct gb_spilib *spi)
	{
	struct gb_spi_master_config_response response;
	u16 mode, flags;
	int ret;

	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_MASTER_CONFIG,
	NULL, 0, &response, sizeof(response));
	if (ret < 0)
	return ret;

	mode = le16_to_cpu(response.mode);
	spi->mode = gb_spi_mode_map(mode);

	flags = le16_to_cpu(response.flags);
	spi->flags = gb_spi_flags_map(flags);

	spi->bits_per_word_mask = le32_to_cpu(response.bits_per_word_mask);
	spi->num_chipselect = response.num_chipselect;

	spi->min_speed_hz = le32_to_cpu(response.min_speed_hz);
	spi->max_speed_hz = le32_to_cpu(response.max_speed_hz);

	return 0;
	}

	static int gb_spi_setup_device(struct gb_spilib *spi, u8 cs)
	{
	struct spi_master *master = get_master_from_spi(spi);
	struct gb_spi_device_config_request request;
	struct gb_spi_device_config_response response;
	struct spi_board_info spi_board = { {0} };
	struct spi_device *spidev;
	int ret;
	u8 dev_type;

	request.chip_select = cs;

	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_DEVICE_CONFIG,
	&request, sizeof(request),
	&response, sizeof(response));
	if (ret < 0)
	return ret;

	dev_type = response.device_type;

	if (dev_type == GB_SPI_SPI_DEV)
	strscpy(spi_board.modalias, "spidev",
	sizeof(spi_board.modalias));
	else if (dev_type == GB_SPI_SPI_NOR)
	strscpy(spi_board.modalias, "spi-nor",
	sizeof(spi_board.modalias));
	else if (dev_type == GB_SPI_SPI_MODALIAS)
	memcpy(spi_board.modalias, response.name,
	sizeof(spi_board.modalias));
	else
	return -EINVAL;

	spi_board.mode = le16_to_cpu(response.mode);
	spi_board.bus_num = master->bus_num;
	spi_board.chip_select = cs;
	spi_board.max_speed_hz = le32_to_cpu(response.max_speed_hz);

	spidev = spi_new_device(master, &spi_board);
	if (!spidev)
	return -EINVAL;

	return 0;
	}

	int gb_spilib_master_init(struct gb_connection connection, struct device dev,
	struct spilib_ops *ops)
	{
	struct gb_spilib *spi;
	struct spi_master *master;
	int ret;
	u8 i;

	/* Allocate master with space for data */
	master = spi_alloc_master(dev, sizeof(*spi));
	if (!master) {
	dev_err(dev, "cannot alloc SPI master\n");
	return -ENOMEM;
	}

	spi = spi_master_get_devdata(master);
	spi->connection = connection;
	gb_connection_set_data(connection, master);
	spi->parent = dev;
	spi->ops = ops;

	/* get master configuration */
	ret = gb_spi_get_master_config(spi);
	if (ret)
	goto exit_spi_put;

	master->bus_num = -1; /* Allow spi-core to allocate it dynamically */
	master->num_chipselect = spi->num_chipselect;
	master->mode_bits = spi->mode;
	master->flags = spi->flags;
	master->bits_per_word_mask = spi->bits_per_word_mask;

	/* Attach methods */
	master->cleanup = gb_spi_cleanup;
	master->setup = gb_spi_setup;
	master->transfer_one_message = gb_spi_transfer_one_message;

	if (ops && ops->prepare_transfer_hardware) {
	master->prepare_transfer_hardware =
	gb_spi_prepare_transfer_hardware;
	}

	if (ops && ops->unprepare_transfer_hardware) {
	master->unprepare_transfer_hardware =
	gb_spi_unprepare_transfer_hardware;
	}

	master->auto_runtime_pm = true;

	ret = spi_register_master(master);
	if (ret < 0)
	goto exit_spi_put;

	/* now, fetch the devices configuration */
	for (i = 0; i < spi->num_chipselect; i++) {
	ret = gb_spi_setup_device(spi, i);
	if (ret < 0) {
	dev_err(dev, "failed to allocate spi device %d: %d\n",
	i, ret);
	goto exit_spi_unregister;
	}
	}

	return 0;

	exit_spi_put:
	spi_master_put(master);

	return ret;

	exit_spi_unregister:
	spi_unregister_master(master);

	return ret;
	}
	EXPORT_SYMBOL_GPL(gb_spilib_master_init);

	void gb_spilib_master_exit(struct gb_connection *connection)
	{
	struct spi_master *master = gb_connection_get_data(connection);

	spi_unregister_master(master);
	}
	EXPORT_SYMBOL_GPL(gb_spilib_master_exit);

	MODULE_LICENSE("GPL v2");