drivers/spi/spi-mem.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (C) 2018 Exceet Electronics GmbH
  * Copyright (C) 2018 Bootlin
  *
  * Author: Boris Brezillon <boris.brezillon@bootlin.com>
  */
 #include <linux/dmaengine.h>
 #include <linux/pm_runtime.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/spi-mem.h>

 #include "internals.h"

 /**
  * spi_controller_dma_map_mem_op_data() - DMA-map the buffer attached to a
  *					  memory operation
  * @ctlr: the SPI controller requesting this dma_map()
  * @op: the memory operation containing the buffer to map
  * @sgt: a pointer to a non-initialized sg_table that will be filled by this
  *	 function
  *
  * Some controllers might want to do DMA on the data buffer embedded in @op.
  * This helper prepares everything for you and provides a ready-to-use
  * sg_table. This function is not intended to be called from spi drivers.
  * Only SPI controller drivers should use it.
  * Note that the caller must ensure the memory region pointed by
  * op->data.buf.{in,out} is DMA-able before calling this function.
  *
  * Return: 0 in case of success, a negative error code otherwise.
  */
 int spi_controller_dma_map_mem_op_data(struct spi_controller *ctlr,
 				       const struct spi_mem_op *op,
 				       struct sg_table *sgt)
 {
 	struct device *dmadev;

 	if (!op->data.nbytes)
 		return -EINVAL;

 	if (op->data.dir == SPI_MEM_DATA_OUT && ctlr->dma_tx)
 		dmadev = ctlr->dma_tx->device->dev;
 	else if (op->data.dir == SPI_MEM_DATA_IN && ctlr->dma_rx)
 		dmadev = ctlr->dma_rx->device->dev;
 	else
 		dmadev = ctlr->dev.parent;

 	if (!dmadev)
 		return -EINVAL;

 	return spi_map_buf(ctlr, dmadev, sgt, op->data.buf.in, op->data.nbytes,
 			   op->data.dir == SPI_MEM_DATA_IN ?
 			   DMA_FROM_DEVICE : DMA_TO_DEVICE);
 }
 EXPORT_SYMBOL_GPL(spi_controller_dma_map_mem_op_data);

 /**
  * spi_controller_dma_unmap_mem_op_data() - DMA-unmap the buffer attached to a
  *					    memory operation
  * @ctlr: the SPI controller requesting this dma_unmap()
  * @op: the memory operation containing the buffer to unmap
  * @sgt: a pointer to an sg_table previously initialized by
  *	 spi_controller_dma_map_mem_op_data()
  *
  * Some controllers might want to do DMA on the data buffer embedded in @op.
  * This helper prepares things so that the CPU can access the
  * op->data.buf.{in,out} buffer again.
  *
  * This function is not intended to be called from SPI drivers. Only SPI
  * controller drivers should use it.
  *
  * This function should be called after the DMA operation has finished and is
  * only valid if the previous spi_controller_dma_map_mem_op_data() call
  * returned 0.
  *
  * Return: 0 in case of success, a negative error code otherwise.
  */
 void spi_controller_dma_unmap_mem_op_data(struct spi_controller *ctlr,
 					  const struct spi_mem_op *op,
 					  struct sg_table *sgt)
 {
 	struct device *dmadev;

 	if (!op->data.nbytes)
 		return;

 	if (op->data.dir == SPI_MEM_DATA_OUT && ctlr->dma_tx)
 		dmadev = ctlr->dma_tx->device->dev;
 	else if (op->data.dir == SPI_MEM_DATA_IN && ctlr->dma_rx)
 		dmadev = ctlr->dma_rx->device->dev;
 	else
 		dmadev = ctlr->dev.parent;

 	spi_unmap_buf(ctlr, dmadev, sgt,
 		      op->data.dir == SPI_MEM_DATA_IN ?
 		      DMA_FROM_DEVICE : DMA_TO_DEVICE);
 }
 EXPORT_SYMBOL_GPL(spi_controller_dma_unmap_mem_op_data);

 static int spi_check_buswidth_req(struct spi_mem *mem, u8 buswidth, bool tx)
 {
 	u32 mode = mem->spi->mode;

 	switch (buswidth) {
 	case 1:
 		return 0;

 	case 2:
 		if ((tx && (mode & (SPI_TX_DUAL | SPI_TX_QUAD))) ||
 		    (!tx && (mode & (SPI_RX_DUAL | SPI_RX_QUAD))))
 			return 0;

 		break;

 	case 4:
 		if ((tx && (mode & SPI_TX_QUAD)) ||
 		    (!tx && (mode & SPI_RX_QUAD)))
 			return 0;

 		break;

 	default:
 		break;
 	}

 	return -ENOTSUPP;
 }

 static bool spi_mem_default_supports_op(struct spi_mem *mem,
 					const struct spi_mem_op *op)
 {
 	if (spi_check_buswidth_req(mem, op->cmd.buswidth, true))
 		return false;

 	if (op->addr.nbytes &&
 	    spi_check_buswidth_req(mem, op->addr.buswidth, true))
 		return false;

 	if (op->dummy.nbytes &&
 	    spi_check_buswidth_req(mem, op->dummy.buswidth, true))
 		return false;

 	if (op->data.nbytes &&
 	    spi_check_buswidth_req(mem, op->data.buswidth,
 				   op->data.dir == SPI_MEM_DATA_OUT))
 		return false;

 	return true;
 }
 EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);

 /**
  * spi_mem_supports_op() - Check if a memory device and the controller it is
  *			   connected to support a specific memory operation
  * @mem: the SPI memory
  * @op: the memory operation to check
  *
  * Some controllers are only supporting Single or Dual IOs, others might only
  * support specific opcodes, or it can even be that the controller and device
  * both support Quad IOs but the hardware prevents you from using it because
  * only 2 IO lines are connected.
  *
  * This function checks whether a specific operation is supported.
  *
  * Return: true if @op is supported, false otherwise.
  */
 bool spi_mem_supports_op(struct spi_mem *mem, const struct spi_mem_op *op)
 {
 	struct spi_controller *ctlr = mem->spi->controller;

 	if (ctlr->mem_ops && ctlr->mem_ops->supports_op)
 		return ctlr->mem_ops->supports_op(mem, op);

 	return spi_mem_default_supports_op(mem, op);
 }
 EXPORT_SYMBOL_GPL(spi_mem_supports_op);

 /**
  * spi_mem_exec_op() - Execute a memory operation
  * @mem: the SPI memory
  * @op: the memory operation to execute
  *
  * Executes a memory operation.
  *
  * This function first checks that @op is supported and then tries to execute
  * it.
  *
  * Return: 0 in case of success, a negative error code otherwise.
  */
 int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
 {
 	unsigned int tmpbufsize, xferpos = 0, totalxferlen = 0;
 	struct spi_controller *ctlr = mem->spi->controller;
 	struct spi_transfer xfers[4] = { };
 	struct spi_message msg;
 	u8 *tmpbuf;
 	int ret;

 	if (!spi_mem_supports_op(mem, op))
 		return -ENOTSUPP;

 	if (ctlr->mem_ops) {
 		/*
 		 * Flush the message queue before executing our SPI memory
 		 * operation to prevent preemption of regular SPI transfers.
 		 */
 		spi_flush_queue(ctlr);

 		if (ctlr->auto_runtime_pm) {
 			ret = pm_runtime_get_sync(ctlr->dev.parent);
 			if (ret < 0) {
 				dev_err(&ctlr->dev,
 					"Failed to power device: %d\n",
 					ret);
 				return ret;
 			}
 		}

 		mutex_lock(&ctlr->bus_lock_mutex);
 		mutex_lock(&ctlr->io_mutex);
 		ret = ctlr->mem_ops->exec_op(mem, op);
 		mutex_unlock(&ctlr->io_mutex);
 		mutex_unlock(&ctlr->bus_lock_mutex);

 		if (ctlr->auto_runtime_pm)
 			pm_runtime_put(ctlr->dev.parent);

 		/*
 		 * Some controllers only optimize specific paths (typically the
 		 * read path) and expect the core to use the regular SPI
 		 * interface in other cases.
 		 */
 		if (!ret || ret != -ENOTSUPP)
 			return ret;
 	}

 	tmpbufsize = sizeof(op->cmd.opcode) + op->addr.nbytes +
 		     op->dummy.nbytes;

 	/*
 	 * Allocate a buffer to transmit the CMD, ADDR cycles with kmalloc() so
 	 * we're guaranteed that this buffer is DMA-able, as required by the
 	 * SPI layer.
 	 */
 	tmpbuf = kzalloc(tmpbufsize, GFP_KERNEL | GFP_DMA);
 	if (!tmpbuf)
 		return -ENOMEM;

 	spi_message_init(&msg);

 	tmpbuf[0] = op->cmd.opcode;
 	xfers[xferpos].tx_buf = tmpbuf;
 	xfers[xferpos].len = sizeof(op->cmd.opcode);
 	xfers[xferpos].tx_nbits = op->cmd.buswidth;
 	spi_message_add_tail(&xfers[xferpos], &msg);
 	xferpos++;
 	totalxferlen++;

 	if (op->addr.nbytes) {
 		int i;

 		for (i = 0; i < op->addr.nbytes; i++)
 			tmpbuf[i + 1] = op->addr.val >>
 					(8 * (op->addr.nbytes - i - 1));

 		xfers[xferpos].tx_buf = tmpbuf + 1;
 		xfers[xferpos].len = op->addr.nbytes;
 		xfers[xferpos].tx_nbits = op->addr.buswidth;
 		spi_message_add_tail(&xfers[xferpos], &msg);
 		xferpos++;
 		totalxferlen += op->addr.nbytes;
 	}

 	if (op->dummy.nbytes) {
 		memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
 		xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
 		xfers[xferpos].len = op->dummy.nbytes;
 		xfers[xferpos].tx_nbits = op->dummy.buswidth;
 		spi_message_add_tail(&xfers[xferpos], &msg);
 		xferpos++;
 		totalxferlen += op->dummy.nbytes;
 	}

 	if (op->data.nbytes) {
 		if (op->data.dir == SPI_MEM_DATA_IN) {
 			xfers[xferpos].rx_buf = op->data.buf.in;
 			xfers[xferpos].rx_nbits = op->data.buswidth;
 		} else {
 			xfers[xferpos].tx_buf = op->data.buf.out;
 			xfers[xferpos].tx_nbits = op->data.buswidth;
 		}

 		xfers[xferpos].len = op->data.nbytes;
 		spi_message_add_tail(&xfers[xferpos], &msg);
 		xferpos++;
 		totalxferlen += op->data.nbytes;
 	}

 	ret = spi_sync(mem->spi, &msg);

 	kfree(tmpbuf);

 	if (ret)
 		return ret;

 	if (msg.actual_length != totalxferlen)
 		return -EIO;

 	return 0;
 }
 EXPORT_SYMBOL_GPL(spi_mem_exec_op);

 /**
  * spi_mem_adjust_op_size() - Adjust the data size of a SPI mem operation to
  *			      match controller limitations
  * @mem: the SPI memory
  * @op: the operation to adjust
  *
  * Some controllers have FIFO limitations and must split a data transfer
  * operation into multiple ones, others require a specific alignment for
  * optimized accesses. This function allows SPI mem drivers to split a single
  * operation into multiple sub-operations when required.
  *
  * Return: a negative error code if the controller can't properly adjust @op,
  *	   0 otherwise. Note that @op->data.nbytes will be updated if @op
  *	   can't be handled in a single step.
  */
 int spi_mem_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
 {
 	struct spi_controller *ctlr = mem->spi->controller;

 	if (ctlr->mem_ops && ctlr->mem_ops->adjust_op_size)
 		return ctlr->mem_ops->adjust_op_size(mem, op);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(spi_mem_adjust_op_size);

 static inline struct spi_mem_driver *to_spi_mem_drv(struct device_driver *drv)
 {
 	return container_of(drv, struct spi_mem_driver, spidrv.driver);
 }

 static int spi_mem_probe(struct spi_device *spi)
 {
 	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
 	struct spi_mem *mem;

 	mem = devm_kzalloc(&spi->dev, sizeof(*mem), GFP_KERNEL);
 	if (!mem)
 		return -ENOMEM;

 	mem->spi = spi;
 	spi_set_drvdata(spi, mem);

 	return memdrv->probe(mem);
 }

 static int spi_mem_remove(struct spi_device *spi)
 {
 	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
 	struct spi_mem *mem = spi_get_drvdata(spi);

 	if (memdrv->remove)
 		return memdrv->remove(mem);

 	return 0;
 }

 static void spi_mem_shutdown(struct spi_device *spi)
 {
 	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
 	struct spi_mem *mem = spi_get_drvdata(spi);

 	if (memdrv->shutdown)
 		memdrv->shutdown(mem);
 }

 /**
  * spi_mem_driver_register_with_owner() - Register a SPI memory driver
  * @memdrv: the SPI memory driver to register
  * @owner: the owner of this driver
  *
  * Registers a SPI memory driver.
  *
  * Return: 0 in case of success, a negative error core otherwise.
  */

 int spi_mem_driver_register_with_owner(struct spi_mem_driver *memdrv,
 				       struct module *owner)
 {
 	memdrv->spidrv.probe = spi_mem_probe;
 	memdrv->spidrv.remove = spi_mem_remove;
 	memdrv->spidrv.shutdown = spi_mem_shutdown;

 	return __spi_register_driver(owner, &memdrv->spidrv);
 }
 EXPORT_SYMBOL_GPL(spi_mem_driver_register_with_owner);

 /**
  * spi_mem_driver_unregister_with_owner() - Unregister a SPI memory driver
  * @memdrv: the SPI memory driver to unregister
  *
  * Unregisters a SPI memory driver.
  */
 void spi_mem_driver_unregister(struct spi_mem_driver *memdrv)
 {
 	spi_unregister_driver(&memdrv->spidrv);
 }
 EXPORT_SYMBOL_GPL(spi_mem_driver_unregister);
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Copyright (C) 2018 Exceet Electronics GmbH
	* Copyright (C) 2018 Bootlin
	*
	* Author: Boris Brezillon <boris.brezillon@bootlin.com>
	*/
	#include <linux/dmaengine.h>
	#include <linux/pm_runtime.h>
	#include <linux/spi/spi.h>
	#include <linux/spi/spi-mem.h>

	#include "internals.h"

	/**
	* spi_controller_dma_map_mem_op_data() - DMA-map the buffer attached to a
	* memory operation
	* @ctlr: the SPI controller requesting this dma_map()
	* @op: the memory operation containing the buffer to map
	* @sgt: a pointer to a non-initialized sg_table that will be filled by this
	* function
	*
	* Some controllers might want to do DMA on the data buffer embedded in @op.
	* This helper prepares everything for you and provides a ready-to-use
	* sg_table. This function is not intended to be called from spi drivers.
	* Only SPI controller drivers should use it.
	* Note that the caller must ensure the memory region pointed by
	* op->data.buf.{in,out} is DMA-able before calling this function.
	*
	* Return: 0 in case of success, a negative error code otherwise.
	*/
	int spi_controller_dma_map_mem_op_data(struct spi_controller *ctlr,
	const struct spi_mem_op *op,
	struct sg_table *sgt)
	{
	struct device *dmadev;

	if (!op->data.nbytes)
	return -EINVAL;

	if (op->data.dir == SPI_MEM_DATA_OUT && ctlr->dma_tx)
	dmadev = ctlr->dma_tx->device->dev;
	else if (op->data.dir == SPI_MEM_DATA_IN && ctlr->dma_rx)
	dmadev = ctlr->dma_rx->device->dev;
	else
	dmadev = ctlr->dev.parent;

	if (!dmadev)
	return -EINVAL;

	return spi_map_buf(ctlr, dmadev, sgt, op->data.buf.in, op->data.nbytes,
	op->data.dir == SPI_MEM_DATA_IN ?
	DMA_FROM_DEVICE : DMA_TO_DEVICE);
	}
	EXPORT_SYMBOL_GPL(spi_controller_dma_map_mem_op_data);

	/**
	* spi_controller_dma_unmap_mem_op_data() - DMA-unmap the buffer attached to a
	* memory operation
	* @ctlr: the SPI controller requesting this dma_unmap()
	* @op: the memory operation containing the buffer to unmap
	* @sgt: a pointer to an sg_table previously initialized by
	* spi_controller_dma_map_mem_op_data()
	*
	* Some controllers might want to do DMA on the data buffer embedded in @op.
	* This helper prepares things so that the CPU can access the
	* op->data.buf.{in,out} buffer again.
	*
	* This function is not intended to be called from SPI drivers. Only SPI
	* controller drivers should use it.
	*
	* This function should be called after the DMA operation has finished and is
	* only valid if the previous spi_controller_dma_map_mem_op_data() call
	* returned 0.
	*
	* Return: 0 in case of success, a negative error code otherwise.
	*/
	void spi_controller_dma_unmap_mem_op_data(struct spi_controller *ctlr,
	const struct spi_mem_op *op,
	struct sg_table *sgt)
	{
	struct device *dmadev;

	if (!op->data.nbytes)
	return;

	if (op->data.dir == SPI_MEM_DATA_OUT && ctlr->dma_tx)
	dmadev = ctlr->dma_tx->device->dev;
	else if (op->data.dir == SPI_MEM_DATA_IN && ctlr->dma_rx)
	dmadev = ctlr->dma_rx->device->dev;
	else
	dmadev = ctlr->dev.parent;

	spi_unmap_buf(ctlr, dmadev, sgt,
	op->data.dir == SPI_MEM_DATA_IN ?
	DMA_FROM_DEVICE : DMA_TO_DEVICE);
	}
	EXPORT_SYMBOL_GPL(spi_controller_dma_unmap_mem_op_data);

	static int spi_check_buswidth_req(struct spi_mem *mem, u8 buswidth, bool tx)
	{
	u32 mode = mem->spi->mode;

	switch (buswidth) {
	case 1:
	return 0;

	case 2:
	if ((tx && (mode & (SPI_TX_DUAL \| SPI_TX_QUAD))) \|\|
	(!tx && (mode & (SPI_RX_DUAL \| SPI_RX_QUAD))))
	return 0;

	break;

	case 4:
	if ((tx && (mode & SPI_TX_QUAD)) \|\|
	(!tx && (mode & SPI_RX_QUAD)))
	return 0;

	break;

	default:
	break;
	}

	return -ENOTSUPP;
	}

	static bool spi_mem_default_supports_op(struct spi_mem *mem,
	const struct spi_mem_op *op)
	{
	if (spi_check_buswidth_req(mem, op->cmd.buswidth, true))
	return false;

	if (op->addr.nbytes &&
	spi_check_buswidth_req(mem, op->addr.buswidth, true))
	return false;

	if (op->dummy.nbytes &&
	spi_check_buswidth_req(mem, op->dummy.buswidth, true))
	return false;

	if (op->data.nbytes &&
	spi_check_buswidth_req(mem, op->data.buswidth,
	op->data.dir == SPI_MEM_DATA_OUT))
	return false;

	return true;
	}
	EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);

	/**
	* spi_mem_supports_op() - Check if a memory device and the controller it is
	* connected to support a specific memory operation
	* @mem: the SPI memory
	* @op: the memory operation to check
	*
	* Some controllers are only supporting Single or Dual IOs, others might only
	* support specific opcodes, or it can even be that the controller and device
	* both support Quad IOs but the hardware prevents you from using it because
	* only 2 IO lines are connected.
	*
	* This function checks whether a specific operation is supported.
	*
	* Return: true if @op is supported, false otherwise.
	*/
	bool spi_mem_supports_op(struct spi_mem mem, const struct spi_mem_op op)
	{
	struct spi_controller *ctlr = mem->spi->controller;

	if (ctlr->mem_ops && ctlr->mem_ops->supports_op)
	return ctlr->mem_ops->supports_op(mem, op);

	return spi_mem_default_supports_op(mem, op);
	}
	EXPORT_SYMBOL_GPL(spi_mem_supports_op);

	/**
	* spi_mem_exec_op() - Execute a memory operation
	* @mem: the SPI memory
	* @op: the memory operation to execute
	*
	* Executes a memory operation.
	*
	* This function first checks that @op is supported and then tries to execute
	* it.
	*
	* Return: 0 in case of success, a negative error code otherwise.
	*/
	int spi_mem_exec_op(struct spi_mem mem, const struct spi_mem_op op)
	{
	unsigned int tmpbufsize, xferpos = 0, totalxferlen = 0;
	struct spi_controller *ctlr = mem->spi->controller;
	struct spi_transfer xfers[4] = { };
	struct spi_message msg;
	u8 *tmpbuf;
	int ret;

	if (!spi_mem_supports_op(mem, op))
	return -ENOTSUPP;

	if (ctlr->mem_ops) {
	/*
	* Flush the message queue before executing our SPI memory
	* operation to prevent preemption of regular SPI transfers.
	*/
	spi_flush_queue(ctlr);

	if (ctlr->auto_runtime_pm) {
	ret = pm_runtime_get_sync(ctlr->dev.parent);
	if (ret < 0) {
	dev_err(&ctlr->dev,
	"Failed to power device: %d\n",
	ret);
	return ret;
	}
	}

	mutex_lock(&ctlr->bus_lock_mutex);
	mutex_lock(&ctlr->io_mutex);
	ret = ctlr->mem_ops->exec_op(mem, op);
	mutex_unlock(&ctlr->io_mutex);
	mutex_unlock(&ctlr->bus_lock_mutex);

	if (ctlr->auto_runtime_pm)
	pm_runtime_put(ctlr->dev.parent);

	/*
	* Some controllers only optimize specific paths (typically the
	* read path) and expect the core to use the regular SPI
	* interface in other cases.
	*/
	if (!ret \|\| ret != -ENOTSUPP)
	return ret;
	}

	tmpbufsize = sizeof(op->cmd.opcode) + op->addr.nbytes +
	op->dummy.nbytes;

	/*
	* Allocate a buffer to transmit the CMD, ADDR cycles with kmalloc() so
	* we're guaranteed that this buffer is DMA-able, as required by the
	* SPI layer.
	*/
	tmpbuf = kzalloc(tmpbufsize, GFP_KERNEL \| GFP_DMA);
	if (!tmpbuf)
	return -ENOMEM;

	spi_message_init(&msg);

	tmpbuf[0] = op->cmd.opcode;
	xfers[xferpos].tx_buf = tmpbuf;
	xfers[xferpos].len = sizeof(op->cmd.opcode);
	xfers[xferpos].tx_nbits = op->cmd.buswidth;
	spi_message_add_tail(&xfers[xferpos], &msg);
	xferpos++;
	totalxferlen++;

	if (op->addr.nbytes) {
	int i;

	for (i = 0; i < op->addr.nbytes; i++)
	tmpbuf[i + 1] = op->addr.val >>
	(8 * (op->addr.nbytes - i - 1));

	xfers[xferpos].tx_buf = tmpbuf + 1;
	xfers[xferpos].len = op->addr.nbytes;
	xfers[xferpos].tx_nbits = op->addr.buswidth;
	spi_message_add_tail(&xfers[xferpos], &msg);
	xferpos++;
	totalxferlen += op->addr.nbytes;
	}

	if (op->dummy.nbytes) {
	memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
	xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
	xfers[xferpos].len = op->dummy.nbytes;
	xfers[xferpos].tx_nbits = op->dummy.buswidth;
	spi_message_add_tail(&xfers[xferpos], &msg);
	xferpos++;
	totalxferlen += op->dummy.nbytes;
	}

	if (op->data.nbytes) {
	if (op->data.dir == SPI_MEM_DATA_IN) {
	xfers[xferpos].rx_buf = op->data.buf.in;
	xfers[xferpos].rx_nbits = op->data.buswidth;
	} else {
	xfers[xferpos].tx_buf = op->data.buf.out;
	xfers[xferpos].tx_nbits = op->data.buswidth;
	}

	xfers[xferpos].len = op->data.nbytes;
	spi_message_add_tail(&xfers[xferpos], &msg);
	xferpos++;
	totalxferlen += op->data.nbytes;
	}

	ret = spi_sync(mem->spi, &msg);

	kfree(tmpbuf);

	if (ret)
	return ret;

	if (msg.actual_length != totalxferlen)
	return -EIO;

	return 0;
	}
	EXPORT_SYMBOL_GPL(spi_mem_exec_op);

	/**
	* spi_mem_adjust_op_size() - Adjust the data size of a SPI mem operation to
	* match controller limitations
	* @mem: the SPI memory
	* @op: the operation to adjust
	*
	* Some controllers have FIFO limitations and must split a data transfer
	* operation into multiple ones, others require a specific alignment for
	* optimized accesses. This function allows SPI mem drivers to split a single
	* operation into multiple sub-operations when required.
	*
	* Return: a negative error code if the controller can't properly adjust @op,
	* 0 otherwise. Note that @op->data.nbytes will be updated if @op
	* can't be handled in a single step.
	*/
	int spi_mem_adjust_op_size(struct spi_mem mem, struct spi_mem_op op)
	{
	struct spi_controller *ctlr = mem->spi->controller;

	if (ctlr->mem_ops && ctlr->mem_ops->adjust_op_size)
	return ctlr->mem_ops->adjust_op_size(mem, op);

	return 0;
	}
	EXPORT_SYMBOL_GPL(spi_mem_adjust_op_size);

	static inline struct spi_mem_driver to_spi_mem_drv(struct device_driver drv)
	{
	return container_of(drv, struct spi_mem_driver, spidrv.driver);
	}

	static int spi_mem_probe(struct spi_device *spi)
	{
	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
	struct spi_mem *mem;

	mem = devm_kzalloc(&spi->dev, sizeof(*mem), GFP_KERNEL);
	if (!mem)
	return -ENOMEM;

	mem->spi = spi;
	spi_set_drvdata(spi, mem);

	return memdrv->probe(mem);
	}

	static int spi_mem_remove(struct spi_device *spi)
	{
	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
	struct spi_mem *mem = spi_get_drvdata(spi);

	if (memdrv->remove)
	return memdrv->remove(mem);

	return 0;
	}

	static void spi_mem_shutdown(struct spi_device *spi)
	{
	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
	struct spi_mem *mem = spi_get_drvdata(spi);

	if (memdrv->shutdown)
	memdrv->shutdown(mem);
	}

	/**
	* spi_mem_driver_register_with_owner() - Register a SPI memory driver
	* @memdrv: the SPI memory driver to register
	* @owner: the owner of this driver
	*
	* Registers a SPI memory driver.
	*
	* Return: 0 in case of success, a negative error core otherwise.
	*/

	int spi_mem_driver_register_with_owner(struct spi_mem_driver *memdrv,
	struct module *owner)
	{
	memdrv->spidrv.probe = spi_mem_probe;
	memdrv->spidrv.remove = spi_mem_remove;
	memdrv->spidrv.shutdown = spi_mem_shutdown;

	return __spi_register_driver(owner, &memdrv->spidrv);
	}
	EXPORT_SYMBOL_GPL(spi_mem_driver_register_with_owner);

	/**
	* spi_mem_driver_unregister_with_owner() - Unregister a SPI memory driver
	* @memdrv: the SPI memory driver to unregister
	*
	* Unregisters a SPI memory driver.
	*/
	void spi_mem_driver_unregister(struct spi_mem_driver *memdrv)
	{
	spi_unregister_driver(&memdrv->spidrv);
	}
	EXPORT_SYMBOL_GPL(spi_mem_driver_unregister);