drivers/spi/spi-oc-tiny.c - linux/kernel/git/viro/vfs - Git at Google


            
            /*

            
             * OpenCores tiny SPI master driver

            
             *

            
             * http://opencores.org/project,tiny_spi

            
             *

            
             * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>

            
             *

            
             * Based on spi_s3c24xx.c, which is:

            
             * 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/interrupt.h>

            
            #include <linux/errno.h>

            
            #include <linux/module.h>

            
            #include <linux/platform_device.h>

            
            #include <linux/spi/spi.h>

            
            #include <linux/spi/spi_bitbang.h>

            
            #include <linux/spi/spi_oc_tiny.h>

            
            #include <linux/io.h>

            
            #include <linux/gpio.h>

            
            #include <linux/of.h>


            #define DRV_NAME "spi_oc_tiny"


            #define TINY_SPI_RXDATA 0

            
            #define TINY_SPI_TXDATA 4

            
            #define TINY_SPI_STATUS 8

            
            #define TINY_SPI_CONTROL 12

            
            #define TINY_SPI_BAUD 16


            #define TINY_SPI_STATUS_TXE 0x1

            
            #define TINY_SPI_STATUS_TXR 0x2


            struct tiny_spi {

            
            	/* bitbang has to be first */

            
            	struct spi_bitbang bitbang;

            
            	struct completion done;


            	void __iomem *base;

            
            	int irq;

            
            	unsigned int freq;

            
            	unsigned int baudwidth;

            
            	unsigned int baud;

            
            	unsigned int speed_hz;

            
            	unsigned int mode;

            
            	unsigned int len;

            
            	unsigned int txc, rxc;

            
            	const u8 *txp;

            
            	u8 *rxp;

            
            	int gpio_cs_count;

            
            	int *gpio_cs;

            
            };


            static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)

            
            {

            
            	return spi_master_get_devdata(sdev->master);

            
            }


            static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)

            
            {

            
            	struct tiny_spi *hw = tiny_spi_to_hw(spi);


            	return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;

            
            }


            static void tiny_spi_chipselect(struct spi_device *spi, int is_active)

            
            {

            
            	struct tiny_spi *hw = tiny_spi_to_hw(spi);


            	if (hw->gpio_cs_count > 0) {

            
            		gpio_set_value(hw->gpio_cs[spi->chip_select],

            
            			(spi->mode & SPI_CS_HIGH) ? is_active : !is_active);

            
            	}

            
            }


            static int tiny_spi_setup_transfer(struct spi_device *spi,

            
            				   struct spi_transfer *t)

            
            {

            
            	struct tiny_spi *hw = tiny_spi_to_hw(spi);

            
            	unsigned int baud = hw->baud;


            	if (t) {

            
            		if (t->speed_hz && t->speed_hz != hw->speed_hz)

            
            			baud = tiny_spi_baud(spi, t->speed_hz);

            
            	}

            
            	writel(baud, hw->base + TINY_SPI_BAUD);

            
            	writel(hw->mode, hw->base + TINY_SPI_CONTROL);

            
            	return 0;

            
            }


            static int tiny_spi_setup(struct spi_device *spi)

            
            {

            
            	struct tiny_spi *hw = tiny_spi_to_hw(spi);


            	if (spi->max_speed_hz != hw->speed_hz) {

            
            		hw->speed_hz = spi->max_speed_hz;

            
            		hw->baud = tiny_spi_baud(spi, hw->speed_hz);

            
            	}

            
            	hw->mode = spi->mode & (SPI_CPOL | SPI_CPHA);

            
            	return 0;

            
            }


            static inline void tiny_spi_wait_txr(struct tiny_spi *hw)

            
            {

            
            	while (!(readb(hw->base + TINY_SPI_STATUS) &

            
            		 TINY_SPI_STATUS_TXR))

            
            		cpu_relax();

            
            }


            static inline void tiny_spi_wait_txe(struct tiny_spi *hw)

            
            {

            
            	while (!(readb(hw->base + TINY_SPI_STATUS) &

            
            		 TINY_SPI_STATUS_TXE))

            
            		cpu_relax();

            
            }


            static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)

            
            {

            
            	struct tiny_spi *hw = tiny_spi_to_hw(spi);

            
            	const u8 *txp = t->tx_buf;

            
            	u8 *rxp = t->rx_buf;

            
            	unsigned int i;


            	if (hw->irq >= 0) {

            
            		/* use interrupt driven data transfer */

            
            		hw->len = t->len;

            
            		hw->txp = t->tx_buf;

            
            		hw->rxp = t->rx_buf;

            
            		hw->txc = 0;

            
            		hw->rxc = 0;


            		/* send the first byte */

            
            		if (t->len > 1) {

            
            			writeb(hw->txp ? *hw->txp++ : 0,

            
            			       hw->base + TINY_SPI_TXDATA);

            
            			hw->txc++;

            
            			writeb(hw->txp ? *hw->txp++ : 0,

            
            			       hw->base + TINY_SPI_TXDATA);

            
            			hw->txc++;

            
            			writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);

            
            		} else {

            
            			writeb(hw->txp ? *hw->txp++ : 0,

            
            			       hw->base + TINY_SPI_TXDATA);

            
            			hw->txc++;

            
            			writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);

            
            		}


            		wait_for_completion(&hw->done);

            
            	} else {

            
            		/* we need to tighten the transfer loop */

            
            		writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);

            
            		for (i = 1; i < t->len; i++) {

            
            			writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);


            			if (rxp || (i != t->len - 1))

            
            				tiny_spi_wait_txr(hw);

            
            			if (rxp)

            
            				*rxp++ = readb(hw->base + TINY_SPI_TXDATA);

            
            		}

            
            		tiny_spi_wait_txe(hw);

            
            		if (rxp)

            
            			*rxp++ = readb(hw->base + TINY_SPI_RXDATA);

            
            	}


            	return t->len;

            
            }


            static irqreturn_t tiny_spi_irq(int irq, void *dev)

            
            {

            
            	struct tiny_spi *hw = dev;


            	writeb(0, hw->base + TINY_SPI_STATUS);

            
            	if (hw->rxc + 1 == hw->len) {

            
            		if (hw->rxp)

            
            			*hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);

            
            		hw->rxc++;

            
            		complete(&hw->done);

            
            	} else {

            
            		if (hw->rxp)

            
            			*hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);

            
            		hw->rxc++;

            
            		if (hw->txc < hw->len) {

            
            			writeb(hw->txp ? *hw->txp++ : 0,

            
            			       hw->base + TINY_SPI_TXDATA);

            
            			hw->txc++;

            
            			writeb(TINY_SPI_STATUS_TXR,

            
            			       hw->base + TINY_SPI_STATUS);

            
            		} else {

            
            			writeb(TINY_SPI_STATUS_TXE,

            
            			       hw->base + TINY_SPI_STATUS);

            
            		}

            
            	}

            
            	return IRQ_HANDLED;

            
            }


            #ifdef CONFIG_OF

            
            #include <linux/of_gpio.h>


            static int tiny_spi_of_probe(struct platform_device *pdev)

            
            {

            
            	struct tiny_spi *hw = platform_get_drvdata(pdev);

            
            	struct device_node *np = pdev->dev.of_node;

            
            	unsigned int i;

            
            	u32 val;


            	if (!np)

            
            		return 0;

            
            	hw->gpio_cs_count = of_gpio_count(np);

            
            	if (hw->gpio_cs_count > 0) {

            
            		hw->gpio_cs = devm_kcalloc(&pdev->dev,

            
            				hw->gpio_cs_count, sizeof(unsigned int),

            
            				GFP_KERNEL);

            
            		if (!hw->gpio_cs)

            
            			return -ENOMEM;

            
            	}

            
            	for (i = 0; i < hw->gpio_cs_count; i++) {

            
            		hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL);

            
            		if (hw->gpio_cs[i] < 0)

            
            			return -ENODEV;

            
            	}

            
            	hw->bitbang.master->dev.of_node = pdev->dev.of_node;

            
            	if (!of_property_read_u32(np, "clock-frequency", &val))

            
            		hw->freq = val;

            
            	if (!of_property_read_u32(np, "baud-width", &val))

            
            		hw->baudwidth = val;

            
            	return 0;

            
            }

            
            #else /* !CONFIG_OF */

            
            static int tiny_spi_of_probe(struct platform_device *pdev)

            
            {

            
            	return 0;

            
            }

            
            #endif /* CONFIG_OF */


            static int tiny_spi_probe(struct platform_device *pdev)

            
            {

            
            	struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);

            
            	struct tiny_spi *hw;

            
            	struct spi_master *master;

            
            	struct resource *res;

            
            	unsigned int i;

            
            	int err = -ENODEV;


            	master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));

            
            	if (!master)

            
            		return err;


            	/* setup the master state. */

            
            	master->bus_num = pdev->id;

            
            	master->num_chipselect = 255;

            
            	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;

            
            	master->setup = tiny_spi_setup;


            	hw = spi_master_get_devdata(master);

            
            	platform_set_drvdata(pdev, hw);


            	/* setup the state for the bitbang driver */

            
            	hw->bitbang.master = master;

            
            	hw->bitbang.setup_transfer = tiny_spi_setup_transfer;

            
            	hw->bitbang.chipselect = tiny_spi_chipselect;

            
            	hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;


            	/* find and map our resources */

            
            	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

            
            	hw->base = devm_ioremap_resource(&pdev->dev, res);

            
            	if (IS_ERR(hw->base)) {

            
            		err = PTR_ERR(hw->base);

            
            		goto exit;

            
            	}

            
            	/* irq is optional */

            
            	hw->irq = platform_get_irq(pdev, 0);

            
            	if (hw->irq >= 0) {

            
            		init_completion(&hw->done);

            
            		err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,

            
            				       pdev->name, hw);

            
            		if (err)

            
            			goto exit;

            
            	}

            
            	/* find platform data */

            
            	if (platp) {

            
            		hw->gpio_cs_count = platp->gpio_cs_count;

            
            		hw->gpio_cs = platp->gpio_cs;

            
            		if (platp->gpio_cs_count && !platp->gpio_cs) {

            
            			err = -EBUSY;

            
            			goto exit;

            
            		}

            
            		hw->freq = platp->freq;

            
            		hw->baudwidth = platp->baudwidth;

            
            	} else {

            
            		err = tiny_spi_of_probe(pdev);

            
            		if (err)

            
            			goto exit;

            
            	}

            
            	for (i = 0; i < hw->gpio_cs_count; i++) {

            
            		err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));

            
            		if (err)

            
            			goto exit_gpio;

            
            		gpio_direction_output(hw->gpio_cs[i], 1);

            
            	}

            
            	hw->bitbang.master->num_chipselect = max(1, hw->gpio_cs_count);


            	/* register our spi controller */

            
            	err = spi_bitbang_start(&hw->bitbang);

            
            	if (err)

            
            		goto exit;

            
            	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);


            	return 0;


            exit_gpio:

            
            	while (i-- > 0)

            
            		gpio_free(hw->gpio_cs[i]);

            
            exit:

            
            	spi_master_put(master);

            
            	return err;

            
            }


            static int tiny_spi_remove(struct platform_device *pdev)

            
            {

            
            	struct tiny_spi *hw = platform_get_drvdata(pdev);

            
            	struct spi_master *master = hw->bitbang.master;

            
            	unsigned int i;


            	spi_bitbang_stop(&hw->bitbang);

            
            	for (i = 0; i < hw->gpio_cs_count; i++)

            
            		gpio_free(hw->gpio_cs[i]);

            
            	spi_master_put(master);

            
            	return 0;

            
            }


            #ifdef CONFIG_OF

            
            static const struct of_device_id tiny_spi_match[] = {

            
            	{ .compatible = "opencores,tiny-spi-rtlsvn2", },

            
            	{},

            
            };

            
            MODULE_DEVICE_TABLE(of, tiny_spi_match);

            
            #endif /* CONFIG_OF */


            static struct platform_driver tiny_spi_driver = {

            
            	.probe = tiny_spi_probe,

            
            	.remove = tiny_spi_remove,

            
            	.driver = {

            
            		.name = DRV_NAME,

            
            		.pm = NULL,

            
            		.of_match_table = of_match_ptr(tiny_spi_match),

            
            	},

            
            };

            
            module_platform_driver(tiny_spi_driver);


            MODULE_DESCRIPTION("OpenCores tiny SPI driver");

            
            MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");

            
            MODULE_LICENSE("GPL");

            
            MODULE_ALIAS("platform:" DRV_NAME);
	/*
	* OpenCores tiny SPI master driver
	*
	* http://opencores.org/project,tiny_spi
	*
	* Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>
	*
	* Based on spi_s3c24xx.c, which is:
	* 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/interrupt.h>
	#include <linux/errno.h>
	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/spi/spi.h>
	#include <linux/spi/spi_bitbang.h>
	#include <linux/spi/spi_oc_tiny.h>
	#include <linux/io.h>
	#include <linux/gpio.h>
	#include <linux/of.h>

	#define DRV_NAME "spi_oc_tiny"

	#define TINY_SPI_RXDATA 0
	#define TINY_SPI_TXDATA 4
	#define TINY_SPI_STATUS 8
	#define TINY_SPI_CONTROL 12
	#define TINY_SPI_BAUD 16

	#define TINY_SPI_STATUS_TXE 0x1
	#define TINY_SPI_STATUS_TXR 0x2

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

	void __iomem *base;
	int irq;
	unsigned int freq;
	unsigned int baudwidth;
	unsigned int baud;
	unsigned int speed_hz;
	unsigned int mode;
	unsigned int len;
	unsigned int txc, rxc;
	const u8 *txp;
	u8 *rxp;
	int gpio_cs_count;
	int *gpio_cs;
	};

	static inline struct tiny_spi tiny_spi_to_hw(struct spi_device sdev)
	{
	return spi_master_get_devdata(sdev->master);
	}

	static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)
	{
	struct tiny_spi *hw = tiny_spi_to_hw(spi);

	return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;
	}

	static void tiny_spi_chipselect(struct spi_device *spi, int is_active)
	{
	struct tiny_spi *hw = tiny_spi_to_hw(spi);

	if (hw->gpio_cs_count > 0) {
	gpio_set_value(hw->gpio_cs[spi->chip_select],
	(spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
	}
	}

	static int tiny_spi_setup_transfer(struct spi_device *spi,
	struct spi_transfer *t)
	{
	struct tiny_spi *hw = tiny_spi_to_hw(spi);
	unsigned int baud = hw->baud;

	if (t) {
	if (t->speed_hz && t->speed_hz != hw->speed_hz)
	baud = tiny_spi_baud(spi, t->speed_hz);
	}
	writel(baud, hw->base + TINY_SPI_BAUD);
	writel(hw->mode, hw->base + TINY_SPI_CONTROL);
	return 0;
	}

	static int tiny_spi_setup(struct spi_device *spi)
	{
	struct tiny_spi *hw = tiny_spi_to_hw(spi);

	if (spi->max_speed_hz != hw->speed_hz) {
	hw->speed_hz = spi->max_speed_hz;
	hw->baud = tiny_spi_baud(spi, hw->speed_hz);
	}
	hw->mode = spi->mode & (SPI_CPOL \| SPI_CPHA);
	return 0;
	}

	static inline void tiny_spi_wait_txr(struct tiny_spi *hw)
	{
	while (!(readb(hw->base + TINY_SPI_STATUS) &
	TINY_SPI_STATUS_TXR))
	cpu_relax();
	}

	static inline void tiny_spi_wait_txe(struct tiny_spi *hw)
	{
	while (!(readb(hw->base + TINY_SPI_STATUS) &
	TINY_SPI_STATUS_TXE))
	cpu_relax();
	}

	static int tiny_spi_txrx_bufs(struct spi_device spi, struct spi_transfer t)
	{
	struct tiny_spi *hw = tiny_spi_to_hw(spi);
	const u8 *txp = t->tx_buf;
	u8 *rxp = t->rx_buf;
	unsigned int i;

	if (hw->irq >= 0) {
	/* use interrupt driven data transfer */
	hw->len = t->len;
	hw->txp = t->tx_buf;
	hw->rxp = t->rx_buf;
	hw->txc = 0;
	hw->rxc = 0;

	/* send the first byte */
	if (t->len > 1) {
	writeb(hw->txp ? *hw->txp++ : 0,
	hw->base + TINY_SPI_TXDATA);
	hw->txc++;
	writeb(hw->txp ? *hw->txp++ : 0,
	hw->base + TINY_SPI_TXDATA);
	hw->txc++;
	writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);
	} else {
	writeb(hw->txp ? *hw->txp++ : 0,
	hw->base + TINY_SPI_TXDATA);
	hw->txc++;
	writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);
	}

	wait_for_completion(&hw->done);
	} else {
	/* we need to tighten the transfer loop */
	writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
	for (i = 1; i < t->len; i++) {
	writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);

	if (rxp \|\| (i != t->len - 1))
	tiny_spi_wait_txr(hw);
	if (rxp)
	*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
	}
	tiny_spi_wait_txe(hw);
	if (rxp)
	*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
	}

	return t->len;
	}

	static irqreturn_t tiny_spi_irq(int irq, void *dev)
	{
	struct tiny_spi *hw = dev;

	writeb(0, hw->base + TINY_SPI_STATUS);
	if (hw->rxc + 1 == hw->len) {
	if (hw->rxp)
	*hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
	hw->rxc++;
	complete(&hw->done);
	} else {
	if (hw->rxp)
	*hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
	hw->rxc++;
	if (hw->txc < hw->len) {
	writeb(hw->txp ? *hw->txp++ : 0,
	hw->base + TINY_SPI_TXDATA);
	hw->txc++;
	writeb(TINY_SPI_STATUS_TXR,
	hw->base + TINY_SPI_STATUS);
	} else {
	writeb(TINY_SPI_STATUS_TXE,
	hw->base + TINY_SPI_STATUS);
	}
	}
	return IRQ_HANDLED;
	}

	#ifdef CONFIG_OF
	#include <linux/of_gpio.h>

	static int tiny_spi_of_probe(struct platform_device *pdev)
	{
	struct tiny_spi *hw = platform_get_drvdata(pdev);
	struct device_node *np = pdev->dev.of_node;
	unsigned int i;
	u32 val;

	if (!np)
	return 0;
	hw->gpio_cs_count = of_gpio_count(np);
	if (hw->gpio_cs_count > 0) {
	hw->gpio_cs = devm_kcalloc(&pdev->dev,
	hw->gpio_cs_count, sizeof(unsigned int),
	GFP_KERNEL);
	if (!hw->gpio_cs)
	return -ENOMEM;
	}
	for (i = 0; i < hw->gpio_cs_count; i++) {
	hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL);
	if (hw->gpio_cs[i] < 0)
	return -ENODEV;
	}
	hw->bitbang.master->dev.of_node = pdev->dev.of_node;
	if (!of_property_read_u32(np, "clock-frequency", &val))
	hw->freq = val;
	if (!of_property_read_u32(np, "baud-width", &val))
	hw->baudwidth = val;
	return 0;
	}
	#else /* !CONFIG_OF */
	static int tiny_spi_of_probe(struct platform_device *pdev)
	{
	return 0;
	}
	#endif /* CONFIG_OF */

	static int tiny_spi_probe(struct platform_device *pdev)
	{
	struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
	struct tiny_spi *hw;
	struct spi_master *master;
	struct resource *res;
	unsigned int i;
	int err = -ENODEV;

	master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
	if (!master)
	return err;

	/* setup the master state. */
	master->bus_num = pdev->id;
	master->num_chipselect = 255;
	master->mode_bits = SPI_CPOL \| SPI_CPHA \| SPI_CS_HIGH;
	master->setup = tiny_spi_setup;

	hw = spi_master_get_devdata(master);
	platform_set_drvdata(pdev, hw);

	/* setup the state for the bitbang driver */
	hw->bitbang.master = master;
	hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
	hw->bitbang.chipselect = tiny_spi_chipselect;
	hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;

	/* find and map our resources */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	hw->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(hw->base)) {
	err = PTR_ERR(hw->base);
	goto exit;
	}
	/* irq is optional */
	hw->irq = platform_get_irq(pdev, 0);
	if (hw->irq >= 0) {
	init_completion(&hw->done);
	err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
	pdev->name, hw);
	if (err)
	goto exit;
	}
	/* find platform data */
	if (platp) {
	hw->gpio_cs_count = platp->gpio_cs_count;
	hw->gpio_cs = platp->gpio_cs;
	if (platp->gpio_cs_count && !platp->gpio_cs) {
	err = -EBUSY;
	goto exit;
	}
	hw->freq = platp->freq;
	hw->baudwidth = platp->baudwidth;
	} else {
	err = tiny_spi_of_probe(pdev);
	if (err)
	goto exit;
	}
	for (i = 0; i < hw->gpio_cs_count; i++) {
	err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));
	if (err)
	goto exit_gpio;
	gpio_direction_output(hw->gpio_cs[i], 1);
	}
	hw->bitbang.master->num_chipselect = max(1, hw->gpio_cs_count);

	/* register our spi controller */
	err = spi_bitbang_start(&hw->bitbang);
	if (err)
	goto exit;
	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);

	return 0;

	exit_gpio:
	while (i-- > 0)
	gpio_free(hw->gpio_cs[i]);
	exit:
	spi_master_put(master);
	return err;
	}

	static int tiny_spi_remove(struct platform_device *pdev)
	{
	struct tiny_spi *hw = platform_get_drvdata(pdev);
	struct spi_master *master = hw->bitbang.master;
	unsigned int i;

	spi_bitbang_stop(&hw->bitbang);
	for (i = 0; i < hw->gpio_cs_count; i++)
	gpio_free(hw->gpio_cs[i]);
	spi_master_put(master);
	return 0;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id tiny_spi_match[] = {
	{ .compatible = "opencores,tiny-spi-rtlsvn2", },
	{},
	};
	MODULE_DEVICE_TABLE(of, tiny_spi_match);
	#endif /* CONFIG_OF */

	static struct platform_driver tiny_spi_driver = {
	.probe = tiny_spi_probe,
	.remove = tiny_spi_remove,
	.driver = {
	.name = DRV_NAME,
	.pm = NULL,
	.of_match_table = of_match_ptr(tiny_spi_match),
	},
	};
	module_platform_driver(tiny_spi_driver);

	MODULE_DESCRIPTION("OpenCores tiny SPI driver");
	MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:" DRV_NAME);