path: root/drivers/spi/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/iopoll.h>
#include <linux/pm_runtime.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi-mem.h>
#include <linux/sched/task_stack.h>

#include "internals.h"

#define SPI_MEM_MAX_BUSWIDTH		8

/**
 * 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 | SPI_TX_OCTAL))) ||
		    (!tx &&
		     (mode & (SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL))))
			return 0;

		break;

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

		break;

	case 8:
		if ((tx && (mode & SPI_TX_OCTAL)) ||
		    (!tx && (mode & SPI_RX_OCTAL)))
			return 0;

		break;

	default:
		break;
	}

	return -ENOTSUPP;
}

static bool spi_mem_check_buswidth(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.dir != SPI_MEM_NO_DATA &&
	    spi_check_buswidth_req(mem, op->data.buswidth,
				   op->data.dir == SPI_MEM_DATA_OUT))
		return false;

	return true;
}

bool spi_mem_default_supports_op(struct spi_mem *mem,
				 const struct spi_mem_op *op)
{
	struct spi_controller *ctlr = mem->spi->controller;
	bool op_is_dtr =
		op->cmd.dtr || op->addr.dtr || op->dummy.dtr || op->data.dtr;

	if (op_is_dtr) {
		if (!spi_mem_controller_is_capable(ctlr, dtr))
			return false;

		if (op->data.swap16 && !spi_mem_controller_is_capable(ctlr, swap16))
			return false;

		if (op->cmd.nbytes != 2)
			return false;
	}