spi-nuc900.c

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/*
 * Copyright (c) 2009 Nuvoton technology.
 * Wan ZongShun <[email protected]>
 *
 * 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/module.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/io.h>
#include <linux/slab.h>

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

#include <linux/platform_data/spi-nuc900.h>

/* usi registers offset */
#define USI_CNT     0x00
#define USI_DIV     0x04
#define USI_SSR     0x08
#define USI_RX0     0x10
#define USI_TX0     0x10

/* usi register bit */
#define ENINT       (0x01 << 17)
#define ENFLG       (0x01 << 16)
#define TXNUM       (0x03 << 8)
#define TXNEG       (0x01 << 2)
#define RXNEG       (0x01 << 1)
#define LSB     (0x01 << 10)
#define SELECTLEV   (0x01 << 2)
#define SELECTPOL   (0x01 << 31)
#define SELECTSLAVE 0x01
#define GOBUSY      0x01

struct nuc900_spi {
    struct spi_bitbang   bitbang;
    struct completion    done;
    void __iomem        *regs;
    int          irq;
    int          len;
    int          count;
    const unsigned char *tx;
    unsigned char       *rx;
    struct clk      *clk;
    struct resource     *ioarea;
    struct spi_master   *master;
    struct spi_device   *curdev;
    struct device       *dev;
    struct nuc900_spi_info *pdata;
    spinlock_t      lock;
    struct resource     *res;
};

static inline struct nuc900_spi *to_hw(struct spi_device *sdev)
{
    return spi_master_get_devdata(sdev->master);
}

static void nuc900_slave_select(struct spi_device *spi, unsigned int ssr)
{
    struct nuc900_spi *hw = to_hw(spi);
    unsigned int val;
    unsigned int cs = spi->mode & SPI_CS_HIGH ? 1 : 0;
    unsigned int cpol = spi->mode & SPI_CPOL ? 1 : 0;
    unsigned long flags;

    spin_lock_irqsave(&hw->lock, flags);

    val = __raw_readl(hw->regs + USI_SSR);

    if (!cs)
        val &= ~SELECTLEV;
    else
        val |= SELECTLEV;

    if (!ssr)
        val &= ~SELECTSLAVE;
    else
        val |= SELECTSLAVE;

    __raw_writel(val, hw->regs + USI_SSR);

    val = __raw_readl(hw->regs + USI_CNT);

    if (!cpol)
        val &= ~SELECTPOL;
    else
        val |= SELECTPOL;

    __raw_writel(val, hw->regs + USI_CNT);

    spin_unlock_irqrestore(&hw->lock, flags);
}

static void nuc900_spi_chipsel(struct spi_device *spi, int value)
{
    switch (value) {
    case BITBANG_CS_INACTIVE:
        nuc900_slave_select(spi, 0);
        break;

    case BITBANG_CS_ACTIVE:
        nuc900_slave_select(spi, 1);
        break;
    }
}

static void nuc900_spi_setup_txnum(struct nuc900_spi *hw,
                            unsigned int txnum)
{
    unsigned int val;
    unsigned long flags;

    spin_lock_irqsave(&hw->lock, flags);

    val = __raw_readl(hw->regs + USI_CNT);

    if (!txnum)
        val &= ~TXNUM;
    else
        val |= txnum << 0x08;

    __raw_writel(val, hw->regs + USI_CNT);

    spin_unlock_irqrestore(&hw->lock, flags);

}

static void nuc900_spi_setup_txbitlen(struct nuc900_spi *hw,
                            unsigned int txbitlen)
{
    unsigned int val;
    unsigned long flags;

    spin_lock_irqsave(&hw->lock, flags);

    val = __raw_readl(hw->regs + USI_CNT);

    val |= (txbitlen << 0x03);

    __raw_writel(val, hw->regs + USI_CNT);

    spin_unlock_irqrestore(&hw->lock, flags);
}

static void nuc900_spi_gobusy(struct nuc900_spi *hw)
{
    unsigned int val;
    unsigned long flags;

    spin_lock_irqsave(&hw->lock, flags);

    val = __raw_readl(hw->regs + USI_CNT);

    val |= GOBUSY;

    __raw_writel(val, hw->regs + USI_CNT);

    spin_unlock_irqrestore(&hw->lock, flags);
}

static int nuc900_spi_setupxfer(struct spi_device *spi,
                 struct spi_transfer *t)
{
    return 0;
}

static int nuc900_spi_setup(struct spi_device *spi)
{
    return 0;
}

static inline unsigned int hw_txbyte(struct nuc900_spi *hw, int count)
{
    return hw->tx ? hw->tx[count] : 0;
}

static int nuc900_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
{
    struct nuc900_spi *hw = to_hw(spi);

    hw->tx = t->tx_buf;
    hw->rx = t->rx_buf;
    hw->len = t->len;
    hw->count = 0;

    __raw_writel(hw_txbyte(hw, 0x0), hw->regs + USI_TX0);

    nuc900_spi_gobusy(hw);

    wait_for_completion(&hw->done);

    return hw->count;
}

static irqreturn_t nuc900_spi_irq(int irq, void *dev)
{
    struct nuc900_spi *hw = dev;
    unsigned int status;
    unsigned int count = hw->count;

    status = __raw_readl(hw->regs + USI_CNT);
    __raw_writel(status, hw->regs + USI_CNT);

    if (status & ENFLG) {
        hw->count++;

        if (hw->rx)
            hw->rx[count] = __raw_readl(hw->regs + USI_RX0);
        count++;

        if (count < hw->len) {
            __raw_writel(hw_txbyte(hw, count), hw->regs + USI_TX0);
            nuc900_spi_gobusy(hw);
        } else {
            complete(&hw->done);
        }

        return IRQ_HANDLED;
    }

    complete(&hw->done);
    return IRQ_HANDLED;
}

static void nuc900_tx_edge(struct nuc900_spi *hw, unsigned int edge)
{
    unsigned int val;
    unsigned long flags;

    spin_lock_irqsave(&hw->lock, flags);

    val = __raw_readl(hw->regs + USI_CNT);

    if (edge)
        val |= TXNEG;
    else
        val &= ~TXNEG;
    __raw_writel(val, hw->regs + USI_CNT);

    spin_unlock_irqrestore(&hw->lock, flags);
}

static void nuc900_rx_edge(struct nuc900_spi *hw, unsigned int edge)
{
    unsigned int val;
    unsigned long flags;

    spin_lock_irqsave(&hw->lock, flags);

    val = __raw_readl(hw->regs + USI_CNT);

    if (edge)
        val |= RXNEG;
    else
        val &= ~RXNEG;
    __raw_writel(val, hw->regs + USI_CNT);

    spin_unlock_irqrestore(&hw->lock, flags);
}

static void nuc900_send_first(struct nuc900_spi *hw, unsigned int lsb)
{
    unsigned int val;
    unsigned long flags;

    spin_lock_irqsave(&hw->lock, flags);

    val = __raw_readl(hw->regs + USI_CNT);

    if (lsb)
        val |= LSB;
    else
        val &= ~LSB;
    __raw_writel(val, hw->regs + USI_CNT);

    spin_unlock_irqrestore(&hw->lock, flags);
}

static void nuc900_set_sleep(struct nuc900_spi *hw, unsigned int sleep)
{
    unsigned int val;
    unsigned long flags;

    spin_lock_irqsave(&hw->lock, flags);

    val = __raw_readl(hw->regs + USI_CNT);

    if (sleep)
        val |= (sleep << 12);
    else
        val &= ~(0x0f << 12);
    __raw_writel(val, hw->regs + USI_CNT);

    spin_unlock_irqrestore(&hw->lock, flags);
}

static void nuc900_enable_int(struct nuc900_spi *hw)
{
    unsigned int val;
    unsigned long flags;

    spin_lock_irqsave(&hw->lock, flags);

    val = __raw_readl(hw->regs + USI_CNT);

    val |= ENINT;

    __raw_writel(val, hw->regs + USI_CNT);

    spin_unlock_irqrestore(&hw->lock, flags);
}

static void nuc900_set_divider(struct nuc900_spi *hw)
{
    __raw_writel(hw->pdata->divider, hw->regs + USI_DIV);
}

static void nuc900_init_spi(struct nuc900_spi *hw)
{
    clk_enable(hw->clk);
    spin_lock_init(&hw->lock);

    nuc900_tx_edge(hw, hw->pdata->txneg);
    nuc900_rx_edge(hw, hw->pdata->rxneg);
    nuc900_send_first(hw, hw->pdata->lsb);
    nuc900_set_sleep(hw, hw->pdata->sleep);
    nuc900_spi_setup_txbitlen(hw, hw->pdata->txbitlen);
    nuc900_spi_setup_txnum(hw, hw->pdata->txnum);
    nuc900_set_divider(hw);
    nuc900_enable_int(hw);
}

static int __devinit nuc900_spi_probe(struct platform_device *pdev)
{
    struct nuc900_spi *hw;
    struct spi_master *master;
    int err = 0;

    master = spi_alloc_master(&pdev->dev, sizeof(struct nuc900_spi));
    if (master == NULL) {
        dev_err(&pdev->dev, "No memory for spi_master\n");
        err = -ENOMEM;
        goto err_nomem;
    }

    hw = spi_master_get_devdata(master);
    hw->master = spi_master_get(master);
    hw->pdata  = pdev->dev.platform_data;
    hw->dev = &pdev->dev;

    if (hw->pdata == NULL) {
        dev_err(&pdev->dev, "No platform data supplied\n");
        err = -ENOENT;
        goto err_pdata;
    }

    platform_set_drvdata(pdev, hw);
    init_completion(&hw->done);

    master->mode_bits          = SPI_MODE_0;
    master->num_chipselect     = hw->pdata->num_cs;
    master->bus_num            = hw->pdata->bus_num;
    hw->bitbang.master         = hw->master;
    hw->bitbang.setup_transfer = nuc900_spi_setupxfer;
    hw->bitbang.chipselect     = nuc900_spi_chipsel;
    hw->bitbang.txrx_bufs      = nuc900_spi_txrx;
    hw->bitbang.master->setup  = nuc900_spi_setup;

    hw->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (hw->res == NULL) {
        dev_err(&pdev->dev, "Cannot get IORESOURCE_MEM\n");
        err = -ENOENT;
        goto err_pdata;
    }

    hw->ioarea = request_mem_region(hw->res->start,
                    resource_size(hw->res), pdev->name);

    if (hw->ioarea == NULL) {
        dev_err(&pdev->dev, "Cannot reserve region\n");
        err = -ENXIO;
        goto err_pdata;
    }

    hw->regs = ioremap(hw->res->start, resource_size(hw->res));
    if (hw->regs == NULL) {
        dev_err(&pdev->dev, "Cannot map IO\n");
        err = -ENXIO;
        goto err_iomap;
    }

    hw->irq = platform_get_irq(pdev, 0);
    if (hw->irq < 0) {
        dev_err(&pdev->dev, "No IRQ specified\n");
        err = -ENOENT;
        goto err_irq;
    }

    err = request_irq(hw->irq, nuc900_spi_irq, 0, pdev->name, hw);
    if (err) {
        dev_err(&pdev->dev, "Cannot claim IRQ\n");
        goto err_irq;
    }

    hw->clk = clk_get(&pdev->dev, "spi");
    if (IS_ERR(hw->clk)) {
        dev_err(&pdev->dev, "No clock for device\n");
        err = PTR_ERR(hw->clk);
        goto err_clk;
    }

    mfp_set_groupg(&pdev->dev, NULL);
    nuc900_init_spi(hw);

    err = spi_bitbang_start(&hw->bitbang);
    if (err) {
        dev_err(&pdev->dev, "Failed to register SPI master\n");
        goto err_register;
    }

    return 0;

err_register:
    clk_disable(hw->clk);
    clk_put(hw->clk);
err_clk:
    free_irq(hw->irq, hw);
err_irq:
    iounmap(hw->regs);
err_iomap:
    release_mem_region(hw->res->start, resource_size(hw->res));
    kfree(hw->ioarea);
err_pdata:
    spi_master_put(hw->master);

err_nomem:
    return err;
}

static int __devexit nuc900_spi_remove(struct platform_device *dev)
{
    struct nuc900_spi *hw = platform_get_drvdata(dev);

    free_irq(hw->irq, hw);

    platform_set_drvdata(dev, NULL);

    spi_bitbang_stop(&hw->bitbang);

    clk_disable(hw->clk);
    clk_put(hw->clk);

    iounmap(hw->regs);

    release_mem_region(hw->res->start, resource_size(hw->res));
    kfree(hw->ioarea);

    spi_master_put(hw->master);
    return 0;
}

static struct platform_driver nuc900_spi_driver = {
    .probe      = nuc900_spi_probe,
    .remove     = __devexit_p(nuc900_spi_remove),
    .driver     = {
        .name   = "nuc900-spi",
        .owner  = THIS_MODULE,
    },
};
module_platform_driver(nuc900_spi_driver);

MODULE_AUTHOR("Wan ZongShun <[email protected]>");
MODULE_DESCRIPTION("nuc900 spi driver!");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:nuc900-spi");