spi-sh-sci.c

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/*
 * SH SCI SPI interface
 *
 * Copyright (c) 2008 Magnus Damm
 *
 * Based on S3C24XX GPIO based SPI driver, which is:
 *   Copyright (c) 2006 Ben Dooks
 *   Copyright (c) 2006 Simtec Electronics
 *
 * 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/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/platform_device.h>

#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/module.h>

#include <asm/spi.h>
#include <asm/io.h>

struct sh_sci_spi {
    struct spi_bitbang bitbang;

    void __iomem *membase;
    unsigned char val;
    struct sh_spi_info *info;
    struct platform_device *dev;
};

#define SCSPTR(sp)  (sp->membase + 0x1c)
#define PIN_SCK     (1 << 2)
#define PIN_TXD     (1 << 0)
#define PIN_RXD     PIN_TXD
#define PIN_INIT    ((1 << 1) | (1 << 3) | PIN_SCK | PIN_TXD)

static inline void setbits(struct sh_sci_spi *sp, int bits, int on)
{
    /*
     * We are the only user of SCSPTR so no locking is required.
     * Reading bit 2 and 0 in SCSPTR gives pin state as input.
     * Writing the same bits sets the output value.
     * This makes regular read-modify-write difficult so we
     * use sp->val to keep track of the latest register value.
     */

    if (on)
        sp->val |= bits;
    else
        sp->val &= ~bits;

    iowrite8(sp->val, SCSPTR(sp));
}

static inline void setsck(struct spi_device *dev, int on)
{
    setbits(spi_master_get_devdata(dev->master), PIN_SCK, on);
}

static inline void setmosi(struct spi_device *dev, int on)
{
    setbits(spi_master_get_devdata(dev->master), PIN_TXD, on);
}

static inline u32 getmiso(struct spi_device *dev)
{
    struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);

    return (ioread8(SCSPTR(sp)) & PIN_RXD) ? 1 : 0;
}

#define spidelay(x) ndelay(x)

#include "spi-bitbang-txrx.h"

static u32 sh_sci_spi_txrx_mode0(struct spi_device *spi,
                      unsigned nsecs, u32 word, u8 bits)
{
    return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
}

static u32 sh_sci_spi_txrx_mode1(struct spi_device *spi,
                      unsigned nsecs, u32 word, u8 bits)
{
    return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
}

static u32 sh_sci_spi_txrx_mode2(struct spi_device *spi,
                      unsigned nsecs, u32 word, u8 bits)
{
    return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
}

static u32 sh_sci_spi_txrx_mode3(struct spi_device *spi,
                      unsigned nsecs, u32 word, u8 bits)
{
    return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
}

static void sh_sci_spi_chipselect(struct spi_device *dev, int value)
{
    struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);

    if (sp->info && sp->info->chip_select)
        (sp->info->chip_select)(sp->info, dev->chip_select, value);
}

static int sh_sci_spi_probe(struct platform_device *dev)
{
    struct resource *r;
    struct spi_master *master;
    struct sh_sci_spi *sp;
    int ret;

    master = spi_alloc_master(&dev->dev, sizeof(struct sh_sci_spi));
    if (master == NULL) {
        dev_err(&dev->dev, "failed to allocate spi master\n");
        ret = -ENOMEM;
        goto err0;
    }

    sp = spi_master_get_devdata(master);

    platform_set_drvdata(dev, sp);
    sp->info = dev->dev.platform_data;

    /* setup spi bitbang adaptor */
    sp->bitbang.master = spi_master_get(master);
    sp->bitbang.master->bus_num = sp->info->bus_num;
    sp->bitbang.master->num_chipselect = sp->info->num_chipselect;
    sp->bitbang.chipselect = sh_sci_spi_chipselect;

    sp->bitbang.txrx_word[SPI_MODE_0] = sh_sci_spi_txrx_mode0;
    sp->bitbang.txrx_word[SPI_MODE_1] = sh_sci_spi_txrx_mode1;
    sp->bitbang.txrx_word[SPI_MODE_2] = sh_sci_spi_txrx_mode2;
    sp->bitbang.txrx_word[SPI_MODE_3] = sh_sci_spi_txrx_mode3;

    r = platform_get_resource(dev, IORESOURCE_MEM, 0);
    if (r == NULL) {
        ret = -ENOENT;
        goto err1;
    }
    sp->membase = ioremap(r->start, resource_size(r));
    if (!sp->membase) {
        ret = -ENXIO;
        goto err1;
    }
    sp->val = ioread8(SCSPTR(sp));
    setbits(sp, PIN_INIT, 1);

    ret = spi_bitbang_start(&sp->bitbang);
    if (!ret)
        return 0;

    setbits(sp, PIN_INIT, 0);
    iounmap(sp->membase);
 err1:
    spi_master_put(sp->bitbang.master);
 err0:
    return ret;
}

static int sh_sci_spi_remove(struct platform_device *dev)
{
    struct sh_sci_spi *sp = platform_get_drvdata(dev);

    iounmap(sp->membase);
    setbits(sp, PIN_INIT, 0);
    spi_bitbang_stop(&sp->bitbang);
    spi_master_put(sp->bitbang.master);
    return 0;
}

static struct platform_driver sh_sci_spi_drv = {
    .probe      = sh_sci_spi_probe,
    .remove     = sh_sci_spi_remove,
    .driver     = {
        .name   = "spi_sh_sci",
        .owner  = THIS_MODULE,
    },
};
module_platform_driver(sh_sci_spi_drv);

MODULE_DESCRIPTION("SH SCI SPI Driver");
MODULE_AUTHOR("Magnus Damm <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:spi_sh_sci");