linux-imx

/*

 * OpenCores tiny SPI master driver

 *

 * http://opencores.org/project,tiny_spi

 *

 * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>

 *

 * Based on spi_s3c24xx.c, which is:

 * Copyright (c) 2006 Ben Dooks

 * Copyright (c) 2006 Simtec Electronics

 *  Ben Dooks <ben@simtec.co.uk>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */

​

#include <linux/interrupt.h>

#include <linux/errno.h>

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/spi/spi.h>

#include <linux/spi/spi_bitbang.h>

#include <linux/spi/spi_oc_tiny.h>

#include <linux/io.h>

#include <linux/gpio.h>

#include <linux/of.h>

​

#define DRV_NAME "spi_oc_tiny"

​

#define TINY_SPI_RXDATA 0

#define TINY_SPI_TXDATA 4

#define TINY_SPI_STATUS 8

#define TINY_SPI_CONTROL 12

#define TINY_SPI_BAUD 16

​

#define TINY_SPI_STATUS_TXE 0x1

#define TINY_SPI_STATUS_TXR 0x2

​

struct tiny_spi {

    /* bitbang has to be first */

    struct spi_bitbang bitbang;

    struct completion done;

​

    void __iomem *base;

    int irq;

    unsigned int freq;

    unsigned int baudwidth;

    unsigned int baud;

    unsigned int speed_hz;

    unsigned int mode;

    unsigned int len;

    unsigned int txc, rxc;

    const u8 *txp;

    u8 *rxp;

    int gpio_cs_count;

    int *gpio_cs;

};

​

static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)

{

    return spi_master_get_devdata(sdev->master);

}

​

static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)

{

    struct tiny_spi *hw = tiny_spi_to_hw(spi);

​

    return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;

}

​

static void tiny_spi_chipselect(struct spi_device *spi, int is_active)

{

    struct tiny_spi *hw = tiny_spi_to_hw(spi);

​

    if (hw->gpio_cs_count > 0) {

        gpio_set_value(hw->gpio_cs[spi->chip_select],

            (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);

    }

}

​

static int tiny_spi_setup_transfer(struct spi_device *spi,

                   struct spi_transfer *t)

{

    struct tiny_spi *hw = tiny_spi_to_hw(spi);

    unsigned int baud = hw->baud;

​

    if (t) {

        if (t->speed_hz && t->speed_hz != hw->speed_hz)

            baud = tiny_spi_baud(spi, t->speed_hz);

    }

    writel(baud, hw->base + TINY_SPI_BAUD);