/* linux/drivers/spi/spi_s3c24xx.c
 *
 * 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/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/platform_device.h>

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

#include <asm/io.h>
#include <asm/dma.h>
#include <asm/hardware.h>

#include <asm/arch/regs-gpio.h>
#include <asm/plat-s3c24xx/regs-spi.h>
#include <asm/arch/spi.h>

struct s3c24xx_spi {
	/* bitbang has to be first */
	struct spi_bitbang	 bitbang;
	struct completion	 done;

	void __iomem		*regs;
	int			 irq;
	int			 len;
	int			 count;

	void			(*set_cs)(struct s3c2410_spi_info *spi,
					  int cs, int pol);

	/* data buffers */
	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 s3c2410_spi_info *pdata;
};

#define SPCON_DEFAULT (S3C2410_SPCON_MSTR | S3C2410_SPCON_SMOD_INT)
#define SPPIN_DEFAULT (S3C2410_SPPIN_KEEP)

static inline struct s3c24xx_spi *to_hw(struct spi_device *sdev)
{
	return spi_master_get_devdata(sdev->master);
}

static void s3c24xx_spi_gpiocs(struct s3c2410_spi_info *spi, int cs, int pol)
{
	s3c2410_gpio_setpin(spi->pin_cs, pol);
}

static void s3c24xx_spi_chipsel(struct spi_device *spi, int value)
{
	struct s3c24xx_spi *hw = to_hw(spi);
	unsigned int cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
	unsigned int spcon;

	switch (value) {
	case BITBANG_CS_INACTIVE:
		hw->set_cs(hw->pdata, spi->chip_select, cspol^1);
		break;

	case BITBANG_CS_ACTIVE:
		spcon = readb(hw->regs + S3C2410_SPCON);

		if (spi->mode & SPI_CPHA)
			spcon |= S3C2410_SPCON_CPHA_FMTB;
		else
			spcon &= ~S3C2410_SPCON_CPHA_FMTB;

		if (spi->mode & SPI_CPOL)
			spcon |= S3C2410_SPCON_CPOL_HIGH;
		else
			spcon &= ~S3C2410_SPCON_CPOL_HIGH;

		spcon |= S3C2410_SPCON_ENSCK;

		/* write new configration */

		writeb(spcon, hw->regs + S3C2410_SPCON);
		hw->set_cs(hw->pdata, spi->chip_select, cspol);

		break;
	}
}

static int s3c24xx_spi_setupxfer(struct spi_device *spi,
				 struct spi_transfer *t)
{
	struct s3c24xx_spi *hw = to_hw(spi);
	unsigned int bpw;
	unsigned int hz;
	unsigned int div;

	bpw = t ? t->bits_per_word : spi->bits_per_word;
	hz  = t ? t->speed_hz : spi->max_speed_hz;

	if (bpw != 8) {
		dev_err(&spi->dev, "invalid bits-per-word (%d)\n", bpw);
		return -EINVAL;
	}

	div = clk_get_rate(hw->clk) / hz;

	/* is clk = pclk / (2 * (pre+1)), or is it
	 *    clk = (pclk * 2) / ( pre + 1) */

	div = (div / 2) - 1;

	if (div < 0)
		div = 1;

	if (div > 255)
		div = 255;

	dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", div, hz);
	writeb(div, hw->regs + S3C2410_SPPRE);

	spin_lock(&hw->bitbang.lock);
	if (!hw->bitbang.busy) {
		hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
		/* need to ndelay for 0.5 clocktick ? */
	}
	spin_unlock(&hw->bitbang.lock);

	return 0;
}

/* the spi->mode bits understood by this driver: */
#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH)

static int s3c24xx_spi_setup(struct spi_device *spi)
{
	int ret;

	if (!spi->bits_per_word)
		spi->bits_per_word = 8;

	if (spi->mode & ~MODEBITS) {
		dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
			spi->mode & ~MODEBITS);
		return -EINVAL;
	}

	ret = s3c24xx_spi_setupxfer(spi, NULL);
	if (ret < 0) {
		dev_err(&spi->dev, "setupxfer returned %d\n", ret);
		return ret;
	}

	dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n",
		__FUNCTION__, spi->mode, spi->bits_per_word,
		spi->max_speed_hz);

	return 0;
}

static inline unsigned int hw_txbyte(struct s3c24xx_spi *hw, int count)
{
	return hw->tx ? hw->tx[count] : 0;
}

static int s3c24xx_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
{
	struct s3c24xx_spi *hw = to_hw(spi);

	dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
		t->tx_buf, t->rx_buf, t->len);

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

	/* send the first byte */
	writeb(hw_txbyte(hw, 0), hw->regs + S3C2410_SPTDAT);
	wait_for_completion(&hw->done);

	return hw->count;
}

static irqreturn_t s3c24xx_spi_irq(int irq, void *dev)
{
	struct s3c24xx_spi *hw = dev;
	unsigned int spsta = readb(hw->regs + S3C2410_SPSTA);
	unsigned int count = hw->count;

	if (spsta & S3C2410_SPSTA_DCOL) {
		dev_dbg(hw->dev, "data-collision\n");
		complete(&hw->done);
		goto irq_done;
	}

	if (!(spsta & S3C2410_SPSTA_READY)) {
		dev_dbg(hw->dev, "spi not ready for tx?\n");
		complete(&hw->done);
		goto irq_done;
	}

	hw->count++;

	if (hw->rx)
		hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT);

	count++;

	if (count < hw->len)
		writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT);
	else
		complete(&hw->done);

 irq_done:
	return IRQ_HANDLED;
}

static int __init s3c24xx_spi_probe(struct platform_device *pdev)
{
	struct s3c24xx_spi *hw;
	struct spi_master *master;
	struct resource *res;
	int err = 0;

	master = spi_alloc_master(&pdev->dev, sizeof(struct s3c24xx_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);
	memset(hw, 0, sizeof(struct s3c24xx_spi));

	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_no_pdata;
	}

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

	/* setup the state for the bitbang driver */

	hw->bitbang.master         = hw->master;
	hw->bitbang.setup_transfer = s3c24xx_spi_setupxfer;
	hw->bitbang.chipselect     = s3c24xx_spi_chipsel;
	hw->bitbang.txrx_bufs      = s3c24xx_spi_txrx;
	hw->bitbang.master->setup  = s3c24xx_spi_setup;

	dev_dbg(hw->dev, "bitbang at %p\n", &hw->bitbang);

	/* find and map our resources */

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

	hw->ioarea = request_mem_region(res->start, (res->end - res->start)+1,
					pdev->name);

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

	hw->regs = ioremap(res->start, (res->end - res->start)+1);
	if (hw->regs == NULL) {
		dev_err(&pdev->dev, "Cannot map IO\n");
		err = -ENXIO;
		goto err_no_iomap;
	}

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

	err = request_irq(hw->irq, s3c24xx_spi_irq, 0, pdev->name, hw);
	if (err) {
		dev_err(&pdev->dev, "Cannot claim IRQ\n");
		goto err_no_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_no_clk;
	}

	/* for the moment, permanently enable the clock */

	clk_enable(hw->clk);

	/* program defaults into the registers */

	writeb(0xff, hw->regs + S3C2410_SPPRE);
	writeb(SPPIN_DEFAULT, hw->regs + S3C2410_SPPIN);
	writeb(SPCON_DEFAULT, hw->regs + S3C2410_SPCON);

	/* setup any gpio we can */

	if (!hw->pdata->set_cs) {
		hw->set_cs = s3c24xx_spi_gpiocs;

		s3c2410_gpio_setpin(hw->pdata->pin_cs, 1);
		s3c2410_gpio_cfgpin(hw->pdata->pin_cs, S3C2410_GPIO_OUTPUT);
	} else
		hw->set_cs = hw->pdata->set_cs;

	/* register our spi controller */

	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_no_clk:
	free_irq(hw->irq, hw);

 err_no_irq:
	iounmap(hw->regs);

 err_no_iomap:
	release_resource(hw->ioarea);
	kfree(hw->ioarea);

 err_no_iores:
 err_no_pdata:
	spi_master_put(hw->master);;

 err_nomem:
	return err;
}

static int __exit s3c24xx_spi_remove(struct platform_device *dev)
{
	struct s3c24xx_spi *hw = platform_get_drvdata(dev);

	platform_set_drvdata(dev, NULL);

	spi_unregister_master(hw->master);

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

	free_irq(hw->irq, hw);
	iounmap(hw->regs);

	release_resource(hw->ioarea);
	kfree(hw->ioarea);

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


#ifdef CONFIG_PM

static int s3c24xx_spi_suspend(struct platform_device *pdev, pm_message_t msg)
{
	struct s3c24xx_spi *hw = platform_get_drvdata(pdev);

	clk_disable(hw->clk);
	return 0;
}

static int s3c24xx_spi_resume(struct platform_device *pdev)
{
	struct s3c24xx_spi *hw = platform_get_drvdata(pdev);

	clk_enable(hw->clk);
	return 0;
}

#else
#define s3c24xx_spi_suspend NULL
#define s3c24xx_spi_resume  NULL
#endif

MODULE_ALIAS("platform:s3c2410-spi");
static struct platform_driver s3c24xx_spidrv = {
	.remove		= __exit_p(s3c24xx_spi_remove),
	.suspend	= s3c24xx_spi_suspend,
	.resume		= s3c24xx_spi_resume,
	.driver		= {
		.name	= "s3c2410-spi",
		.owner	= THIS_MODULE,
	},
};

static int __init s3c24xx_spi_init(void)
{
        return platform_driver_probe(&s3c24xx_spidrv, s3c24xx_spi_probe);
}

static void __exit s3c24xx_spi_exit(void)
{
        platform_driver_unregister(&s3c24xx_spidrv);
}

module_init(s3c24xx_spi_init);
module_exit(s3c24xx_spi_exit);

MODULE_DESCRIPTION("S3C24XX SPI Driver");
MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");