linux-imx

// SPDX-License-Identifier: GPL-2.0+

//

// Freescale MXS SPI master driver

//

// Copyright 2012 DENX Software Engineering, GmbH.

// Copyright 2012 Freescale Semiconductor, Inc.

// Copyright 2008 Embedded Alley Solutions, Inc All Rights Reserved.

//

// Rework and transition to new API by:

// Marek Vasut <marex@denx.de>

//

// Based on previous attempt by:

// Fabio Estevam <fabio.estevam@freescale.com>

//

// Based on code from U-Boot bootloader by:

// Marek Vasut <marex@denx.de>

//

// Based on spi-stmp.c, which is:

// Author: Dmitry Pervushin <dimka@embeddedalley.com>

​

#include <linux/kernel.h>

#include <linux/ioport.h>

#include <linux/of.h>

#include <linux/of_device.h>

#include <linux/of_gpio.h>

#include <linux/platform_device.h>

#include <linux/delay.h>

#include <linux/interrupt.h>

#include <linux/dma-mapping.h>

#include <linux/dmaengine.h>

#include <linux/highmem.h>

#include <linux/clk.h>

#include <linux/err.h>

#include <linux/completion.h>

#include <linux/gpio.h>

#include <linux/regulator/consumer.h>

#include <linux/pm_runtime.h>

#include <linux/module.h>

#include <linux/stmp_device.h>

#include <linux/spi/spi.h>

#include <linux/spi/mxs-spi.h>

#include <trace/events/spi.h>

​

#define DRIVER_NAME     "mxs-spi"

​

/* Use 10S timeout for very long transfers, it should suffice. */

#define SSP_TIMEOUT     10000

​

#define SG_MAXLEN       0xff00

​

/*

 * Flags for txrx functions.  More efficient that using an argument register for

 * each one.

 */

#define TXRX_WRITE      (1<<0)  /* This is a write */

#define TXRX_DEASSERT_CS    (1<<1)  /* De-assert CS at end of txrx */

​

struct mxs_spi {

    struct mxs_ssp      ssp;

    struct completion   c;

    unsigned int        sck;    /* Rate requested (vs actual) */

};

​

static int mxs_spi_setup_transfer(struct spi_device *dev,

                  const struct spi_transfer *t)

{

    struct mxs_spi *spi = spi_master_get_devdata(dev->master);

    struct mxs_ssp *ssp = &spi->ssp;

    const unsigned int hz = min(dev->max_speed_hz, t->speed_hz);

​

    if (hz == 0) {

        dev_err(&dev->dev, "SPI clock rate of zero not allowed\n");

        return -EINVAL;

    }

​

    if (hz != spi->sck) {

        mxs_ssp_set_clk_rate(ssp, hz);

        /*

         * Save requested rate, hz, rather than the actual rate,

         * ssp->clk_rate.  Otherwise we would set the rate every transfer

         * when the actual rate is not quite the same as requested rate.

         */

        spi->sck = hz;

        /*

         * Perhaps we should return an error if the actual clock is

         * nowhere close to what was requested?

         */

    }

​

    writel(BM_SSP_CTRL0_LOCK_CS,

        ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);

​