linux-imx

/*

 *  Copyright (c) 2008-2014 STMicroelectronics Limited

 *

 *  Author: Angus Clark <Angus.Clark@st.com>

 *          Patrice Chotard <patrice.chotard@st.com>

 *          Lee Jones <lee.jones@linaro.org>

 *

 *  SPI master mode controller driver, used in STMicroelectronics devices.

 *

 *  May be copied or modified under the terms of the GNU General Public

 *  License Version 2.0 only.  See linux/COPYING for more information.

 */

​

#include <linux/clk.h>

#include <linux/delay.h>

#include <linux/interrupt.h>

#include <linux/io.h>

#include <linux/module.h>

#include <linux/pinctrl/consumer.h>

#include <linux/platform_device.h>

#include <linux/of.h>

#include <linux/of_gpio.h>

#include <linux/of_irq.h>

#include <linux/pm_runtime.h>

#include <linux/spi/spi.h>

#include <linux/spi/spi_bitbang.h>

​

/* SSC registers */

#define SSC_BRG             0x000

#define SSC_TBUF            0x004

#define SSC_RBUF            0x008

#define SSC_CTL             0x00C

#define SSC_IEN             0x010

#define SSC_I2C             0x018

​

/* SSC Control */

#define SSC_CTL_DATA_WIDTH_9        0x8

#define SSC_CTL_DATA_WIDTH_MSK      0xf

#define SSC_CTL_BM          0xf

#define SSC_CTL_HB          BIT(4)

#define SSC_CTL_PH          BIT(5)

#define SSC_CTL_PO          BIT(6)

#define SSC_CTL_SR          BIT(7)

#define SSC_CTL_MS          BIT(8)

#define SSC_CTL_EN          BIT(9)

#define SSC_CTL_LPB         BIT(10)

#define SSC_CTL_EN_TX_FIFO      BIT(11)

#define SSC_CTL_EN_RX_FIFO      BIT(12)

#define SSC_CTL_EN_CLST_RX      BIT(13)

​

/* SSC Interrupt Enable */

#define SSC_IEN_TEEN            BIT(2)

​

#define FIFO_SIZE           8

​

struct spi_st {

    /* SSC SPI Controller */

    void __iomem        *base;

    struct clk      *clk;

    struct device       *dev;

​

    /* SSC SPI current transaction */

    const u8        *tx_ptr;

    u8          *rx_ptr;

    u16         bytes_per_word;

    unsigned int        words_remaining;

    unsigned int        baud;

    struct completion   done;

};

​

/* Load the TX FIFO */

static void ssc_write_tx_fifo(struct spi_st *spi_st)

{

    unsigned int count, i;

    uint32_t word = 0;

​

    if (spi_st->words_remaining > FIFO_SIZE)

        count = FIFO_SIZE;

    else

        count = spi_st->words_remaining;

​

    for (i = 0; i < count; i++) {

        if (spi_st->tx_ptr) {

            if (spi_st->bytes_per_word == 1) {

                word = *spi_st->tx_ptr++;

            } else {

                word = *spi_st->tx_ptr++;

                word = *spi_st->tx_ptr++ | (word << 8);

            }

        }

        writel_relaxed(word, spi_st->base + SSC_TBUF);

    }