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/* 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/gpio.h>

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

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

#include <plat/regs-spi.h>
#include <mach/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)
{
	gpio_set_value(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 /= 2;

	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;
}

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

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

	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;

	init_completion(&hw->done);

	/* 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)) {