spi-mem.c

// 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"

#define SPI_MEM_MAX_BUSWIDTH		4

/**
 * 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);

static bool spi_mem_buswidth_is_valid(u8 buswidth)
{
	if (hweight8(buswidth) > 1 || buswidth > SPI_MEM_MAX_BUSWIDTH)
		return false;

	return true;
}

static int spi_mem_check_op(const struct spi_mem_op *op)
{
	if (!op->cmd.buswidth)
		return -EINVAL;

	if ((op->addr.nbytes && !op->addr.buswidth) ||
	    (op->dummy.nbytes && !op->dummy.buswidth) ||
	    (op->data.nbytes && !op->data.buswidth))
		return -EINVAL;

	if (spi_mem_buswidth_is_valid(op->cmd.buswidth) ||
	    spi_mem_buswidth_is_valid(op->addr.buswidth) ||
	    spi_mem_buswidth_is_valid(op->dummy.buswidth) ||
	    spi_mem_buswidth_is_valid(op->data.buswidth))
		return -EINVAL;

	return 0;
}

static bool spi_mem_internal_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);
}

/**
 * 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)
{
	if (spi_mem_check_op(op))
		return false;

	return spi_mem_internal_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;

	ret = spi_mem_check_op(op);
	if (ret)
		return ret;

	if (!spi_mem_internal_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_get_name() - Return the SPI mem device name to be used by the
 *			upper layer if necessary
 * @mem: the SPI memory
 *
 * This function allows SPI mem users to retrieve the SPI mem device name.
 * It is useful if the upper layer needs to expose a custom name for
 * compatibility reasons.
 *
 * Return: a string containing the name of the memory device to be used
 *	   by the SPI mem user
 */
const char *spi_mem_get_name(struct spi_mem *mem)
{
	return mem->name;
}
EXPORT_SYMBOL_GPL(spi_mem_get_name);

/**
 * 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;
	size_t len;

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

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

	if (!ctlr->mem_ops || !ctlr->mem_ops->exec_op) {
		if (len > spi_max_transfer_size(mem->spi))
			return -EINVAL;

		op->data.nbytes = min3((size_t)op->data.nbytes,
				       spi_max_transfer_size(mem->spi),
				       spi_max_message_size(mem->spi) -
				       len);
		if (!op->data.nbytes)
			return -EINVAL;
	}

	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_controller *ctlr = spi->controller;
	struct spi_mem *mem;

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

	mem->spi = spi;

	if (ctlr->mem_ops && ctlr->mem_ops->get_name)
		mem->name = ctlr->mem_ops->get_name(mem);
	else
		mem->name = dev_name(&spi->dev);

	if (IS_ERR_OR_NULL(mem->name))
		return PTR_ERR(mem->name);

	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);