drivers/spi/spi-oc-tiny.c - maze/linux - 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/init.h>
 #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;
 	unsigned 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) {
 		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 if (txp && rxp) {
 		/* we need to tighten the transfer loop */
 		writeb(*txp++, hw->base + TINY_SPI_TXDATA);
 		if (t->len > 1) {
 			writeb(*txp++, hw->base + TINY_SPI_TXDATA);
 			for (i = 2; i < t->len; i++) {
 				u8 rx, tx = *txp++;
 				tiny_spi_wait_txr(hw);
 				rx = readb(hw->base + TINY_SPI_TXDATA);
 				writeb(tx, hw->base + TINY_SPI_TXDATA);
 				*rxp++ = rx;
 			}
 			tiny_spi_wait_txr(hw);
 			*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 		}
 		tiny_spi_wait_txe(hw);
 		*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 	} else if (rxp) {
 		writeb(0, hw->base + TINY_SPI_TXDATA);
 		if (t->len > 1) {
 			writeb(0,
 			       hw->base + TINY_SPI_TXDATA);
 			for (i = 2; i < t->len; i++) {
 				u8 rx;
 				tiny_spi_wait_txr(hw);
 				rx = readb(hw->base + TINY_SPI_TXDATA);
 				writeb(0, hw->base + TINY_SPI_TXDATA);
 				*rxp++ = rx;
 			}
 			tiny_spi_wait_txr(hw);
 			*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 		}
 		tiny_spi_wait_txe(hw);
 		*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 	} else if (txp) {
 		writeb(*txp++, hw->base + TINY_SPI_TXDATA);
 		if (t->len > 1) {
 			writeb(*txp++, hw->base + TINY_SPI_TXDATA);
 			for (i = 2; i < t->len; i++) {
 				u8 tx = *txp++;
 				tiny_spi_wait_txr(hw);
 				writeb(tx, hw->base + TINY_SPI_TXDATA);
 			}
 		}
 		tiny_spi_wait_txe(hw);
 	} else {
 		writeb(0, hw->base + TINY_SPI_TXDATA);
 		if (t->len > 1) {
 			writeb(0, hw->base + TINY_SPI_TXDATA);
 			for (i = 2; i < t->len; i++) {
 				tiny_spi_wait_txr(hw);
 				writeb(0, hw->base + TINY_SPI_TXDATA);
 			}
 		}
 		tiny_spi_wait_txe(hw);
 	}
 	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 __devinit 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;
 	const __be32 *val;
 	int len;

 	if (!np)
 		return 0;
 	hw->gpio_cs_count = of_gpio_count(np);
 	if (hw->gpio_cs_count) {
 		hw->gpio_cs = devm_kzalloc(&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;
 	val = of_get_property(pdev->dev.of_node,
 			      "clock-frequency", &len);
 	if (val && len >= sizeof(__be32))
 		hw->freq = be32_to_cpup(val);
 	val = of_get_property(pdev->dev.of_node, "baud-width", &len);
 	if (val && len >= sizeof(__be32))
 		hw->baudwidth = be32_to_cpup(val);
 	return 0;
 }
 #else /* !CONFIG_OF */
 static int __devinit tiny_spi_of_probe(struct platform_device *pdev)
 {
 	return 0;
 }
 #endif /* CONFIG_OF */

 static int __devinit tiny_spi_probe(struct platform_device *pdev)
 {
 	struct tiny_spi_platform_data *platp = pdev->dev.platform_data;
 	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 = spi_master_get(master);
 	if (!hw->bitbang.master)
 		return err;
 	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);
 	if (!res)
 		goto exit_busy;
 	if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
 				     pdev->name))
 		goto exit_busy;
 	hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
 					resource_size(res));
 	if (!hw->base)
 		goto exit_busy;
 	/* 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)
 			goto exit_busy;
 		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(1U, 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_busy:
 	err = -EBUSY;
 exit:
 	platform_set_drvdata(pdev, NULL);
 	spi_master_put(master);
 	return err;
 }

 static int __devexit 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]);
 	platform_set_drvdata(pdev, NULL);
 	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);
 #else /* CONFIG_OF */
 #define tiny_spi_match NULL
 #endif /* CONFIG_OF */

 static struct platform_driver tiny_spi_driver = {
 	.probe = tiny_spi_probe,
 	.remove = __devexit_p(tiny_spi_remove),
 	.driver = {
 		.name = DRV_NAME,
 		.owner = THIS_MODULE,
 		.pm = NULL,
 		.of_match_table = 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/init.h>
	#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;
	unsigned 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) {
	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 if (txp && rxp) {
	/* we need to tighten the transfer loop */
	writeb(*txp++, hw->base + TINY_SPI_TXDATA);
	if (t->len > 1) {
	writeb(*txp++, hw->base + TINY_SPI_TXDATA);
	for (i = 2; i < t->len; i++) {
	u8 rx, tx = *txp++;
	tiny_spi_wait_txr(hw);
	rx = readb(hw->base + TINY_SPI_TXDATA);
	writeb(tx, hw->base + TINY_SPI_TXDATA);
	*rxp++ = rx;
	}
	tiny_spi_wait_txr(hw);
	*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
	}
	tiny_spi_wait_txe(hw);
	*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
	} else if (rxp) {
	writeb(0, hw->base + TINY_SPI_TXDATA);
	if (t->len > 1) {
	writeb(0,
	hw->base + TINY_SPI_TXDATA);
	for (i = 2; i < t->len; i++) {
	u8 rx;
	tiny_spi_wait_txr(hw);
	rx = readb(hw->base + TINY_SPI_TXDATA);
	writeb(0, hw->base + TINY_SPI_TXDATA);
	*rxp++ = rx;
	}
	tiny_spi_wait_txr(hw);
	*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
	}
	tiny_spi_wait_txe(hw);
	*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
	} else if (txp) {
	writeb(*txp++, hw->base + TINY_SPI_TXDATA);
	if (t->len > 1) {
	writeb(*txp++, hw->base + TINY_SPI_TXDATA);
	for (i = 2; i < t->len; i++) {
	u8 tx = *txp++;
	tiny_spi_wait_txr(hw);
	writeb(tx, hw->base + TINY_SPI_TXDATA);
	}
	}
	tiny_spi_wait_txe(hw);
	} else {
	writeb(0, hw->base + TINY_SPI_TXDATA);
	if (t->len > 1) {
	writeb(0, hw->base + TINY_SPI_TXDATA);
	for (i = 2; i < t->len; i++) {
	tiny_spi_wait_txr(hw);
	writeb(0, hw->base + TINY_SPI_TXDATA);
	}
	}
	tiny_spi_wait_txe(hw);
	}
	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 __devinit 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;
	const __be32 *val;
	int len;

	if (!np)
	return 0;
	hw->gpio_cs_count = of_gpio_count(np);
	if (hw->gpio_cs_count) {
	hw->gpio_cs = devm_kzalloc(&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;
	val = of_get_property(pdev->dev.of_node,
	"clock-frequency", &len);
	if (val && len >= sizeof(__be32))
	hw->freq = be32_to_cpup(val);
	val = of_get_property(pdev->dev.of_node, "baud-width", &len);
	if (val && len >= sizeof(__be32))
	hw->baudwidth = be32_to_cpup(val);
	return 0;
	}
	#else /* !CONFIG_OF */
	static int __devinit tiny_spi_of_probe(struct platform_device *pdev)
	{
	return 0;
	}
	#endif /* CONFIG_OF */

	static int __devinit tiny_spi_probe(struct platform_device *pdev)
	{
	struct tiny_spi_platform_data *platp = pdev->dev.platform_data;
	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 = spi_master_get(master);
	if (!hw->bitbang.master)
	return err;
	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);
	if (!res)
	goto exit_busy;
	if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
	pdev->name))
	goto exit_busy;
	hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
	resource_size(res));
	if (!hw->base)
	goto exit_busy;
	/* 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)
	goto exit_busy;
	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(1U, 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_busy:
	err = -EBUSY;
	exit:
	platform_set_drvdata(pdev, NULL);
	spi_master_put(master);
	return err;
	}

	static int __devexit 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]);
	platform_set_drvdata(pdev, NULL);
	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);
	#else /* CONFIG_OF */
	#define tiny_spi_match NULL
	#endif /* CONFIG_OF */

	static struct platform_driver tiny_spi_driver = {
	.probe = tiny_spi_probe,
	.remove = __devexit_p(tiny_spi_remove),
	.driver = {
	.name = DRV_NAME,
	.owner = THIS_MODULE,
	.pm = NULL,
	.of_match_table = 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);