linux-imx

/*

 * polling/bitbanging SPI master controller driver utilities

 *

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

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 */

​

#include <linux/spinlock.h>

#include <linux/workqueue.h>

#include <linux/interrupt.h>

#include <linux/module.h>

#include <linux/delay.h>

#include <linux/errno.h>

#include <linux/platform_device.h>

#include <linux/slab.h>

​

#include <linux/spi/spi.h>

#include <linux/spi/spi_bitbang.h>

​

#define SPI_BITBANG_CS_DELAY    100

​

​

/*----------------------------------------------------------------------*/

​

/*

 * FIRST PART (OPTIONAL):  word-at-a-time spi_transfer support.

 * Use this for GPIO or shift-register level hardware APIs.

 *

 * spi_bitbang_cs is in spi_device->controller_state, which is unavailable

 * to glue code.  These bitbang setup() and cleanup() routines are always

 * used, though maybe they're called from controller-aware code.

 *

 * chipselect() and friends may use spi_device->controller_data and

 * controller registers as appropriate.

 *

 *

 * NOTE:  SPI controller pins can often be used as GPIO pins instead,

 * which means you could use a bitbang driver either to get hardware

 * working quickly, or testing for differences that aren't speed related.

 */

​

struct spi_bitbang_cs {

    unsigned    nsecs;  /* (clock cycle time)/2 */

    u32     (*txrx_word)(struct spi_device *spi, unsigned nsecs,

                    u32 word, u8 bits, unsigned flags);

    unsigned    (*txrx_bufs)(struct spi_device *,

                    u32 (*txrx_word)(

                        struct spi_device *spi,

                        unsigned nsecs,

                        u32 word, u8 bits,

                        unsigned flags),

                    unsigned, struct spi_transfer *,

                    unsigned);

};

​

static unsigned bitbang_txrx_8(