drivers/spi/spi-efm32.c - linux - Git at Google

 /*
  * Copyright (C) 2012-2013 Uwe Kleine-Koenig for Pengutronix
  *
  * 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/kernel.h>
 #include <linux/io.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/spi_bitbang.h>
 #include <linux/gpio.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/of_gpio.h>
 #include <linux/platform_data/efm32-spi.h>

 #define DRIVER_NAME "efm32-spi"

 #define MASK_VAL(mask, val)		((val << __ffs(mask)) & mask)

 #define REG_CTRL		0x00
 #define REG_CTRL_SYNC			0x0001
 #define REG_CTRL_CLKPOL			0x0100
 #define REG_CTRL_CLKPHA			0x0200
 #define REG_CTRL_MSBF			0x0400
 #define REG_CTRL_TXBIL			0x1000

 #define REG_FRAME		0x04
 #define REG_FRAME_DATABITS__MASK	0x000f
 #define REG_FRAME_DATABITS(n)		((n) - 3)

 #define REG_CMD			0x0c
 #define REG_CMD_RXEN			0x0001
 #define REG_CMD_RXDIS			0x0002
 #define REG_CMD_TXEN			0x0004
 #define REG_CMD_TXDIS			0x0008
 #define REG_CMD_MASTEREN		0x0010

 #define REG_STATUS		0x10
 #define REG_STATUS_TXENS		0x0002
 #define REG_STATUS_TXC			0x0020
 #define REG_STATUS_TXBL			0x0040
 #define REG_STATUS_RXDATAV		0x0080

 #define REG_CLKDIV		0x14

 #define REG_RXDATAX		0x18
 #define REG_RXDATAX_RXDATA__MASK	0x01ff
 #define REG_RXDATAX_PERR		0x4000
 #define REG_RXDATAX_FERR		0x8000

 #define REG_TXDATA		0x34

 #define REG_IF		0x40
 #define REG_IF_TXBL			0x0002
 #define REG_IF_RXDATAV			0x0004

 #define REG_IFS		0x44
 #define REG_IFC		0x48
 #define REG_IEN		0x4c

 #define REG_ROUTE		0x54
 #define REG_ROUTE_RXPEN			0x0001
 #define REG_ROUTE_TXPEN			0x0002
 #define REG_ROUTE_CLKPEN		0x0008
 #define REG_ROUTE_LOCATION__MASK	0x0700
 #define REG_ROUTE_LOCATION(n)		MASK_VAL(REG_ROUTE_LOCATION__MASK, (n))

 struct efm32_spi_ddata {
 	struct spi_bitbang bitbang;

 	spinlock_t lock;

 	struct clk *clk;
 	void __iomem *base;
 	unsigned int rxirq, txirq;
 	struct efm32_spi_pdata pdata;

 	/* irq data */
 	struct completion done;
 	const u8 *tx_buf;
 	u8 *rx_buf;
 	unsigned tx_len, rx_len;

 	/* chip selects */
 	unsigned csgpio[];
 };

 #define ddata_to_dev(ddata)	(&(ddata->bitbang.master->dev))
 #define efm32_spi_vdbg(ddata, format, arg...)	\
 	dev_vdbg(ddata_to_dev(ddata), format, ##arg)

 static void efm32_spi_write32(struct efm32_spi_ddata *ddata,
 		u32 value, unsigned offset)
 {
 	writel_relaxed(value, ddata->base + offset);
 }

 static u32 efm32_spi_read32(struct efm32_spi_ddata *ddata, unsigned offset)
 {
 	return readl_relaxed(ddata->base + offset);
 }

 static void efm32_spi_chipselect(struct spi_device *spi, int is_on)
 {
 	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);
 	int value = !(spi->mode & SPI_CS_HIGH) == !(is_on == BITBANG_CS_ACTIVE);

 	gpio_set_value(ddata->csgpio[spi->chip_select], value);
 }

 static int efm32_spi_setup_transfer(struct spi_device *spi,
 		struct spi_transfer *t)
 {
 	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);

 	unsigned bpw = t->bits_per_word ?: spi->bits_per_word;
 	unsigned speed = t->speed_hz ?: spi->max_speed_hz;
 	unsigned long clkfreq = clk_get_rate(ddata->clk);
 	u32 clkdiv;

 	efm32_spi_write32(ddata, REG_CTRL_SYNC | REG_CTRL_MSBF |
 			(spi->mode & SPI_CPHA ? REG_CTRL_CLKPHA : 0) |
 			(spi->mode & SPI_CPOL ? REG_CTRL_CLKPOL : 0), REG_CTRL);

 	efm32_spi_write32(ddata,
 			REG_FRAME_DATABITS(bpw), REG_FRAME);

 	if (2 * speed >= clkfreq)
 		clkdiv = 0;
 	else
 		clkdiv = 64 * (DIV_ROUND_UP(2 * clkfreq, speed) - 4);

 	if (clkdiv > (1U << 21))
 		return -EINVAL;

 	efm32_spi_write32(ddata, clkdiv, REG_CLKDIV);
 	efm32_spi_write32(ddata, REG_CMD_MASTEREN, REG_CMD);
 	efm32_spi_write32(ddata, REG_CMD_RXEN | REG_CMD_TXEN, REG_CMD);

 	return 0;
 }

 static void efm32_spi_tx_u8(struct efm32_spi_ddata *ddata)
 {
 	u8 val = 0;

 	if (ddata->tx_buf) {
 		val = *ddata->tx_buf;
 		ddata->tx_buf++;
 	}

 	ddata->tx_len--;
 	efm32_spi_write32(ddata, val, REG_TXDATA);
 	efm32_spi_vdbg(ddata, "%s: tx 0x%x\n", __func__, val);
 }

 static void efm32_spi_rx_u8(struct efm32_spi_ddata *ddata)
 {
 	u32 rxdata = efm32_spi_read32(ddata, REG_RXDATAX);
 	efm32_spi_vdbg(ddata, "%s: rx 0x%x\n", __func__, rxdata);

 	if (ddata->rx_buf) {
 		*ddata->rx_buf = rxdata;
 		ddata->rx_buf++;
 	}

 	ddata->rx_len--;
 }

 static void efm32_spi_filltx(struct efm32_spi_ddata *ddata)
 {
 	while (ddata->tx_len &&
 			ddata->tx_len + 2 > ddata->rx_len &&
 			efm32_spi_read32(ddata, REG_STATUS) & REG_STATUS_TXBL) {
 		efm32_spi_tx_u8(ddata);
 	}
 }

 static int efm32_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
 {
 	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);
 	int ret = -EBUSY;

 	spin_lock_irq(&ddata->lock);

 	if (ddata->tx_buf || ddata->rx_buf)
 		goto out_unlock;

 	ddata->tx_buf = t->tx_buf;
 	ddata->rx_buf = t->rx_buf;
 	ddata->tx_len = ddata->rx_len =
 		t->len * DIV_ROUND_UP(t->bits_per_word, 8);

 	efm32_spi_filltx(ddata);

 	init_completion(&ddata->done);

 	efm32_spi_write32(ddata, REG_IF_TXBL | REG_IF_RXDATAV, REG_IEN);

 	spin_unlock_irq(&ddata->lock);

 	wait_for_completion(&ddata->done);

 	spin_lock_irq(&ddata->lock);

 	ret = t->len - max(ddata->tx_len, ddata->rx_len);

 	efm32_spi_write32(ddata, 0, REG_IEN);
 	ddata->tx_buf = ddata->rx_buf = NULL;

 out_unlock:
 	spin_unlock_irq(&ddata->lock);

 	return ret;
 }

 static irqreturn_t efm32_spi_rxirq(int irq, void *data)
 {
 	struct efm32_spi_ddata *ddata = data;
 	irqreturn_t ret = IRQ_NONE;

 	spin_lock(&ddata->lock);

 	while (ddata->rx_len > 0 &&
 			efm32_spi_read32(ddata, REG_STATUS) &
 			REG_STATUS_RXDATAV) {
 		efm32_spi_rx_u8(ddata);

 		ret = IRQ_HANDLED;
 	}

 	if (!ddata->rx_len) {
 		u32 ien = efm32_spi_read32(ddata, REG_IEN);

 		ien &= ~REG_IF_RXDATAV;

 		efm32_spi_write32(ddata, ien, REG_IEN);

 		complete(&ddata->done);
 	}

 	spin_unlock(&ddata->lock);

 	return ret;
 }

 static irqreturn_t efm32_spi_txirq(int irq, void *data)
 {
 	struct efm32_spi_ddata *ddata = data;

 	efm32_spi_vdbg(ddata,
 			"%s: txlen = %u, rxlen = %u, if=0x%08x, stat=0x%08x\n",
 			__func__, ddata->tx_len, ddata->rx_len,
 			efm32_spi_read32(ddata, REG_IF),
 			efm32_spi_read32(ddata, REG_STATUS));

 	spin_lock(&ddata->lock);

 	efm32_spi_filltx(ddata);

 	efm32_spi_vdbg(ddata, "%s: txlen = %u, rxlen = %u\n",
 			__func__, ddata->tx_len, ddata->rx_len);

 	if (!ddata->tx_len) {
 		u32 ien = efm32_spi_read32(ddata, REG_IEN);

 		ien &= ~REG_IF_TXBL;

 		efm32_spi_write32(ddata, ien, REG_IEN);
 		efm32_spi_vdbg(ddata, "disable TXBL\n");
 	}

 	spin_unlock(&ddata->lock);

 	return IRQ_HANDLED;
 }

 static u32 efm32_spi_get_configured_location(struct efm32_spi_ddata *ddata)
 {
 	u32 reg = efm32_spi_read32(ddata, REG_ROUTE);

 	return (reg & REG_ROUTE_LOCATION__MASK) >> __ffs(REG_ROUTE_LOCATION__MASK);
 }

 static int efm32_spi_probe_dt(struct platform_device *pdev,
 		struct spi_master *master, struct efm32_spi_ddata *ddata)
 {
 	struct device_node *np = pdev->dev.of_node;
 	u32 location;
 	int ret;

 	if (!np)
 		return 1;

 	ret = of_property_read_u32(np, "location", &location);
 	if (!ret) {
 		dev_dbg(&pdev->dev, "using location %u\n", location);
 	} else {
 		/* default to location configured in hardware */
 		location = efm32_spi_get_configured_location(ddata);

 		dev_info(&pdev->dev, "fall back to location %u\n", location);
 	}

 	ddata->pdata.location = location;

 	/* spi core takes care about the bus number using an alias */
 	master->bus_num = -1;

 	return 0;
 }

 static int efm32_spi_probe(struct platform_device *pdev)
 {
 	struct efm32_spi_ddata *ddata;
 	struct resource *res;
 	int ret;
 	struct spi_master *master;
 	struct device_node *np = pdev->dev.of_node;
 	unsigned int num_cs, i;

 	num_cs = of_gpio_named_count(np, "cs-gpios");

 	master = spi_alloc_master(&pdev->dev,
 			sizeof(*ddata) + num_cs * sizeof(unsigned));
 	if (!master) {
 		dev_dbg(&pdev->dev,
 				"failed to allocate spi master controller\n");
 		return -ENOMEM;
 	}
 	platform_set_drvdata(pdev, master);

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

 	master->num_chipselect = num_cs;
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 16);

 	ddata = spi_master_get_devdata(master);

 	ddata->bitbang.master = master;
 	ddata->bitbang.chipselect = efm32_spi_chipselect;
 	ddata->bitbang.setup_transfer = efm32_spi_setup_transfer;
 	ddata->bitbang.txrx_bufs = efm32_spi_txrx_bufs;

 	spin_lock_init(&ddata->lock);

 	ddata->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(ddata->clk)) {
 		ret = PTR_ERR(ddata->clk);
 		dev_err(&pdev->dev, "failed to get clock: %d\n", ret);
 		goto err;
 	}

 	for (i = 0; i < num_cs; ++i) {
 		ret = of_get_named_gpio(np, "cs-gpios", i);
 		if (ret < 0) {
 			dev_err(&pdev->dev, "failed to get csgpio#%u (%d)\n",
 					i, ret);
 			goto err;
 		}
 		ddata->csgpio[i] = ret;
 		dev_dbg(&pdev->dev, "csgpio#%u = %u\n", i, ddata->csgpio[i]);
 		ret = devm_gpio_request_one(&pdev->dev, ddata->csgpio[i],
 				GPIOF_OUT_INIT_LOW, DRIVER_NAME);
 		if (ret < 0) {
 			dev_err(&pdev->dev,
 					"failed to configure csgpio#%u (%d)\n",
 					i, ret);
 			goto err;
 		}
 	}

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
 		ret = -ENODEV;
 		dev_err(&pdev->dev, "failed to determine base address\n");
 		goto err;
 	}

 	if (resource_size(res) < 0x60) {
 		ret = -EINVAL;
 		dev_err(&pdev->dev, "memory resource too small\n");
 		goto err;
 	}

 	ddata->base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(ddata->base)) {
 		ret = PTR_ERR(ddata->base);
 		goto err;
 	}

 	ret = platform_get_irq(pdev, 0);
 	if (ret <= 0) {
 		dev_err(&pdev->dev, "failed to get rx irq (%d)\n", ret);
 		goto err;
 	}

 	ddata->rxirq = ret;

 	ret = platform_get_irq(pdev, 1);
 	if (ret <= 0)
 		ret = ddata->rxirq + 1;

 	ddata->txirq = ret;

 	ret = clk_prepare_enable(ddata->clk);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to enable clock (%d)\n", ret);
 		goto err;
 	}

 	ret = efm32_spi_probe_dt(pdev, master, ddata);
 	if (ret > 0) {
 		/* not created by device tree */
 		const struct efm32_spi_pdata *pdata =
 			dev_get_platdata(&pdev->dev);

 		if (pdata)
 			ddata->pdata = *pdata;
 		else
 			ddata->pdata.location =
 				efm32_spi_get_configured_location(ddata);

 		master->bus_num = pdev->id;

 	} else if (ret < 0) {
 		goto err_disable_clk;
 	}

 	efm32_spi_write32(ddata, 0, REG_IEN);
 	efm32_spi_write32(ddata, REG_ROUTE_TXPEN | REG_ROUTE_RXPEN |
 			REG_ROUTE_CLKPEN |
 			REG_ROUTE_LOCATION(ddata->pdata.location), REG_ROUTE);

 	ret = request_irq(ddata->rxirq, efm32_spi_rxirq,
 			0, DRIVER_NAME " rx", ddata);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to register rxirq (%d)\n", ret);
 		goto err_disable_clk;
 	}

 	ret = request_irq(ddata->txirq, efm32_spi_txirq,
 			0, DRIVER_NAME " tx", ddata);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to register txirq (%d)\n", ret);
 		goto err_free_rx_irq;
 	}

 	ret = spi_bitbang_start(&ddata->bitbang);
 	if (ret) {
 		dev_err(&pdev->dev, "spi_bitbang_start failed (%d)\n", ret);

 		free_irq(ddata->txirq, ddata);
 err_free_rx_irq:
 		free_irq(ddata->rxirq, ddata);
 err_disable_clk:
 		clk_disable_unprepare(ddata->clk);
 err:
 		spi_master_put(master);
 	}

 	return ret;
 }

 static int efm32_spi_remove(struct platform_device *pdev)
 {
 	struct spi_master *master = platform_get_drvdata(pdev);
 	struct efm32_spi_ddata *ddata = spi_master_get_devdata(master);

 	spi_bitbang_stop(&ddata->bitbang);

 	efm32_spi_write32(ddata, 0, REG_IEN);

 	free_irq(ddata->txirq, ddata);
 	free_irq(ddata->rxirq, ddata);
 	clk_disable_unprepare(ddata->clk);
 	spi_master_put(master);

 	return 0;
 }

 static const struct of_device_id efm32_spi_dt_ids[] = {
 	{
 		.compatible = "efm32,spi",
 	}, {
 		/* sentinel */
 	}
 };
 MODULE_DEVICE_TABLE(of, efm32_spi_dt_ids);

 static struct platform_driver efm32_spi_driver = {
 	.probe = efm32_spi_probe,
 	.remove = efm32_spi_remove,

 	.driver = {
 		.name = DRIVER_NAME,
 		.owner = THIS_MODULE,
 		.of_match_table = efm32_spi_dt_ids,
 	},
 };
 module_platform_driver(efm32_spi_driver);

 MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
 MODULE_DESCRIPTION("EFM32 SPI driver");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:" DRIVER_NAME);
	/*
	* Copyright (C) 2012-2013 Uwe Kleine-Koenig for Pengutronix
	*
	* 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/kernel.h>
	#include <linux/io.h>
	#include <linux/spi/spi.h>
	#include <linux/spi/spi_bitbang.h>
	#include <linux/gpio.h>
	#include <linux/interrupt.h>
	#include <linux/platform_device.h>
	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/module.h>
	#include <linux/of_gpio.h>
	#include <linux/platform_data/efm32-spi.h>

	#define DRIVER_NAME "efm32-spi"

	#define MASK_VAL(mask, val) ((val << __ffs(mask)) & mask)

	#define REG_CTRL 0x00
	#define REG_CTRL_SYNC 0x0001
	#define REG_CTRL_CLKPOL 0x0100
	#define REG_CTRL_CLKPHA 0x0200
	#define REG_CTRL_MSBF 0x0400
	#define REG_CTRL_TXBIL 0x1000

	#define REG_FRAME 0x04
	#define REG_FRAME_DATABITS__MASK 0x000f
	#define REG_FRAME_DATABITS(n) ((n) - 3)

	#define REG_CMD 0x0c
	#define REG_CMD_RXEN 0x0001
	#define REG_CMD_RXDIS 0x0002
	#define REG_CMD_TXEN 0x0004
	#define REG_CMD_TXDIS 0x0008
	#define REG_CMD_MASTEREN 0x0010

	#define REG_STATUS 0x10
	#define REG_STATUS_TXENS 0x0002
	#define REG_STATUS_TXC 0x0020
	#define REG_STATUS_TXBL 0x0040
	#define REG_STATUS_RXDATAV 0x0080

	#define REG_CLKDIV 0x14

	#define REG_RXDATAX 0x18
	#define REG_RXDATAX_RXDATA__MASK 0x01ff
	#define REG_RXDATAX_PERR 0x4000
	#define REG_RXDATAX_FERR 0x8000

	#define REG_TXDATA 0x34

	#define REG_IF 0x40
	#define REG_IF_TXBL 0x0002
	#define REG_IF_RXDATAV 0x0004

	#define REG_IFS 0x44
	#define REG_IFC 0x48
	#define REG_IEN 0x4c

	#define REG_ROUTE 0x54
	#define REG_ROUTE_RXPEN 0x0001
	#define REG_ROUTE_TXPEN 0x0002
	#define REG_ROUTE_CLKPEN 0x0008
	#define REG_ROUTE_LOCATION__MASK 0x0700
	#define REG_ROUTE_LOCATION(n) MASK_VAL(REG_ROUTE_LOCATION__MASK, (n))

	struct efm32_spi_ddata {
	struct spi_bitbang bitbang;

	spinlock_t lock;

	struct clk *clk;
	void __iomem *base;
	unsigned int rxirq, txirq;
	struct efm32_spi_pdata pdata;

	/* irq data */
	struct completion done;
	const u8 *tx_buf;
	u8 *rx_buf;
	unsigned tx_len, rx_len;

	/* chip selects */
	unsigned csgpio[];
	};

	#define ddata_to_dev(ddata) (&(ddata->bitbang.master->dev))
	#define efm32_spi_vdbg(ddata, format, arg...) \
	dev_vdbg(ddata_to_dev(ddata), format, ##arg)

	static void efm32_spi_write32(struct efm32_spi_ddata *ddata,
	u32 value, unsigned offset)
	{
	writel_relaxed(value, ddata->base + offset);
	}

	static u32 efm32_spi_read32(struct efm32_spi_ddata *ddata, unsigned offset)
	{
	return readl_relaxed(ddata->base + offset);
	}

	static void efm32_spi_chipselect(struct spi_device *spi, int is_on)
	{
	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);
	int value = !(spi->mode & SPI_CS_HIGH) == !(is_on == BITBANG_CS_ACTIVE);

	gpio_set_value(ddata->csgpio[spi->chip_select], value);
	}

	static int efm32_spi_setup_transfer(struct spi_device *spi,
	struct spi_transfer *t)
	{
	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);

	unsigned bpw = t->bits_per_word ?: spi->bits_per_word;
	unsigned speed = t->speed_hz ?: spi->max_speed_hz;
	unsigned long clkfreq = clk_get_rate(ddata->clk);
	u32 clkdiv;

	efm32_spi_write32(ddata, REG_CTRL_SYNC \| REG_CTRL_MSBF \|
	(spi->mode & SPI_CPHA ? REG_CTRL_CLKPHA : 0) \|
	(spi->mode & SPI_CPOL ? REG_CTRL_CLKPOL : 0), REG_CTRL);

	efm32_spi_write32(ddata,
	REG_FRAME_DATABITS(bpw), REG_FRAME);

	if (2 * speed >= clkfreq)
	clkdiv = 0;
	else
	clkdiv = 64 * (DIV_ROUND_UP(2 * clkfreq, speed) - 4);

	if (clkdiv > (1U << 21))
	return -EINVAL;

	efm32_spi_write32(ddata, clkdiv, REG_CLKDIV);
	efm32_spi_write32(ddata, REG_CMD_MASTEREN, REG_CMD);
	efm32_spi_write32(ddata, REG_CMD_RXEN \| REG_CMD_TXEN, REG_CMD);

	return 0;
	}

	static void efm32_spi_tx_u8(struct efm32_spi_ddata *ddata)
	{
	u8 val = 0;

	if (ddata->tx_buf) {
	val = *ddata->tx_buf;
	ddata->tx_buf++;
	}

	ddata->tx_len--;
	efm32_spi_write32(ddata, val, REG_TXDATA);
	efm32_spi_vdbg(ddata, "%s: tx 0x%x\n", __func__, val);
	}

	static void efm32_spi_rx_u8(struct efm32_spi_ddata *ddata)
	{
	u32 rxdata = efm32_spi_read32(ddata, REG_RXDATAX);
	efm32_spi_vdbg(ddata, "%s: rx 0x%x\n", __func__, rxdata);

	if (ddata->rx_buf) {
	*ddata->rx_buf = rxdata;
	ddata->rx_buf++;
	}

	ddata->rx_len--;
	}

	static void efm32_spi_filltx(struct efm32_spi_ddata *ddata)
	{
	while (ddata->tx_len &&
	ddata->tx_len + 2 > ddata->rx_len &&
	efm32_spi_read32(ddata, REG_STATUS) & REG_STATUS_TXBL) {
	efm32_spi_tx_u8(ddata);
	}
	}

	static int efm32_spi_txrx_bufs(struct spi_device spi, struct spi_transfer t)
	{
	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);
	int ret = -EBUSY;

	spin_lock_irq(&ddata->lock);

	if (ddata->tx_buf \|\| ddata->rx_buf)
	goto out_unlock;

	ddata->tx_buf = t->tx_buf;
	ddata->rx_buf = t->rx_buf;
	ddata->tx_len = ddata->rx_len =
	t->len * DIV_ROUND_UP(t->bits_per_word, 8);

	efm32_spi_filltx(ddata);

	init_completion(&ddata->done);

	efm32_spi_write32(ddata, REG_IF_TXBL \| REG_IF_RXDATAV, REG_IEN);

	spin_unlock_irq(&ddata->lock);

	wait_for_completion(&ddata->done);

	spin_lock_irq(&ddata->lock);

	ret = t->len - max(ddata->tx_len, ddata->rx_len);

	efm32_spi_write32(ddata, 0, REG_IEN);
	ddata->tx_buf = ddata->rx_buf = NULL;

	out_unlock:
	spin_unlock_irq(&ddata->lock);

	return ret;
	}

	static irqreturn_t efm32_spi_rxirq(int irq, void *data)
	{
	struct efm32_spi_ddata *ddata = data;
	irqreturn_t ret = IRQ_NONE;

	spin_lock(&ddata->lock);

	while (ddata->rx_len > 0 &&
	efm32_spi_read32(ddata, REG_STATUS) &
	REG_STATUS_RXDATAV) {
	efm32_spi_rx_u8(ddata);

	ret = IRQ_HANDLED;
	}

	if (!ddata->rx_len) {
	u32 ien = efm32_spi_read32(ddata, REG_IEN);

	ien &= ~REG_IF_RXDATAV;

	efm32_spi_write32(ddata, ien, REG_IEN);

	complete(&ddata->done);
	}

	spin_unlock(&ddata->lock);

	return ret;
	}

	static irqreturn_t efm32_spi_txirq(int irq, void *data)
	{
	struct efm32_spi_ddata *ddata = data;

	efm32_spi_vdbg(ddata,
	"%s: txlen = %u, rxlen = %u, if=0x%08x, stat=0x%08x\n",
	__func__, ddata->tx_len, ddata->rx_len,
	efm32_spi_read32(ddata, REG_IF),
	efm32_spi_read32(ddata, REG_STATUS));

	spin_lock(&ddata->lock);

	efm32_spi_filltx(ddata);

	efm32_spi_vdbg(ddata, "%s: txlen = %u, rxlen = %u\n",
	__func__, ddata->tx_len, ddata->rx_len);

	if (!ddata->tx_len) {
	u32 ien = efm32_spi_read32(ddata, REG_IEN);

	ien &= ~REG_IF_TXBL;

	efm32_spi_write32(ddata, ien, REG_IEN);
	efm32_spi_vdbg(ddata, "disable TXBL\n");
	}

	spin_unlock(&ddata->lock);

	return IRQ_HANDLED;
	}

	static u32 efm32_spi_get_configured_location(struct efm32_spi_ddata *ddata)
	{
	u32 reg = efm32_spi_read32(ddata, REG_ROUTE);

	return (reg & REG_ROUTE_LOCATION__MASK) >> __ffs(REG_ROUTE_LOCATION__MASK);
	}

	static int efm32_spi_probe_dt(struct platform_device *pdev,
	struct spi_master master, struct efm32_spi_ddata ddata)
	{
	struct device_node *np = pdev->dev.of_node;
	u32 location;
	int ret;

	if (!np)
	return 1;

	ret = of_property_read_u32(np, "location", &location);
	if (!ret) {
	dev_dbg(&pdev->dev, "using location %u\n", location);
	} else {
	/* default to location configured in hardware */
	location = efm32_spi_get_configured_location(ddata);

	dev_info(&pdev->dev, "fall back to location %u\n", location);
	}

	ddata->pdata.location = location;

	/* spi core takes care about the bus number using an alias */
	master->bus_num = -1;

	return 0;
	}

	static int efm32_spi_probe(struct platform_device *pdev)
	{
	struct efm32_spi_ddata *ddata;
	struct resource *res;
	int ret;
	struct spi_master *master;
	struct device_node *np = pdev->dev.of_node;
	unsigned int num_cs, i;

	num_cs = of_gpio_named_count(np, "cs-gpios");

	master = spi_alloc_master(&pdev->dev,
	sizeof(ddata) + num_cs sizeof(unsigned));
	if (!master) {
	dev_dbg(&pdev->dev,
	"failed to allocate spi master controller\n");
	return -ENOMEM;
	}
	platform_set_drvdata(pdev, master);

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

	master->num_chipselect = num_cs;
	master->mode_bits = SPI_CPOL \| SPI_CPHA \| SPI_CS_HIGH;
	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 16);

	ddata = spi_master_get_devdata(master);

	ddata->bitbang.master = master;
	ddata->bitbang.chipselect = efm32_spi_chipselect;
	ddata->bitbang.setup_transfer = efm32_spi_setup_transfer;
	ddata->bitbang.txrx_bufs = efm32_spi_txrx_bufs;

	spin_lock_init(&ddata->lock);

	ddata->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(ddata->clk)) {
	ret = PTR_ERR(ddata->clk);
	dev_err(&pdev->dev, "failed to get clock: %d\n", ret);
	goto err;
	}

	for (i = 0; i < num_cs; ++i) {
	ret = of_get_named_gpio(np, "cs-gpios", i);
	if (ret < 0) {
	dev_err(&pdev->dev, "failed to get csgpio#%u (%d)\n",
	i, ret);
	goto err;
	}
	ddata->csgpio[i] = ret;
	dev_dbg(&pdev->dev, "csgpio#%u = %u\n", i, ddata->csgpio[i]);
	ret = devm_gpio_request_one(&pdev->dev, ddata->csgpio[i],
	GPIOF_OUT_INIT_LOW, DRIVER_NAME);
	if (ret < 0) {
	dev_err(&pdev->dev,
	"failed to configure csgpio#%u (%d)\n",
	i, ret);
	goto err;
	}
	}

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
	ret = -ENODEV;
	dev_err(&pdev->dev, "failed to determine base address\n");
	goto err;
	}

	if (resource_size(res) < 0x60) {
	ret = -EINVAL;
	dev_err(&pdev->dev, "memory resource too small\n");
	goto err;
	}

	ddata->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(ddata->base)) {
	ret = PTR_ERR(ddata->base);
	goto err;
	}

	ret = platform_get_irq(pdev, 0);
	if (ret <= 0) {
	dev_err(&pdev->dev, "failed to get rx irq (%d)\n", ret);
	goto err;
	}

	ddata->rxirq = ret;

	ret = platform_get_irq(pdev, 1);
	if (ret <= 0)
	ret = ddata->rxirq + 1;

	ddata->txirq = ret;

	ret = clk_prepare_enable(ddata->clk);
	if (ret < 0) {
	dev_err(&pdev->dev, "failed to enable clock (%d)\n", ret);
	goto err;
	}

	ret = efm32_spi_probe_dt(pdev, master, ddata);
	if (ret > 0) {
	/* not created by device tree */
	const struct efm32_spi_pdata *pdata =
	dev_get_platdata(&pdev->dev);

	if (pdata)
	ddata->pdata = *pdata;
	else
	ddata->pdata.location =
	efm32_spi_get_configured_location(ddata);

	master->bus_num = pdev->id;

	} else if (ret < 0) {
	goto err_disable_clk;
	}

	efm32_spi_write32(ddata, 0, REG_IEN);
	efm32_spi_write32(ddata, REG_ROUTE_TXPEN \| REG_ROUTE_RXPEN \|
	REG_ROUTE_CLKPEN \|
	REG_ROUTE_LOCATION(ddata->pdata.location), REG_ROUTE);

	ret = request_irq(ddata->rxirq, efm32_spi_rxirq,
	0, DRIVER_NAME " rx", ddata);
	if (ret) {
	dev_err(&pdev->dev, "failed to register rxirq (%d)\n", ret);
	goto err_disable_clk;
	}

	ret = request_irq(ddata->txirq, efm32_spi_txirq,
	0, DRIVER_NAME " tx", ddata);
	if (ret) {
	dev_err(&pdev->dev, "failed to register txirq (%d)\n", ret);
	goto err_free_rx_irq;
	}

	ret = spi_bitbang_start(&ddata->bitbang);
	if (ret) {
	dev_err(&pdev->dev, "spi_bitbang_start failed (%d)\n", ret);

	free_irq(ddata->txirq, ddata);
	err_free_rx_irq:
	free_irq(ddata->rxirq, ddata);
	err_disable_clk:
	clk_disable_unprepare(ddata->clk);
	err:
	spi_master_put(master);
	}

	return ret;
	}

	static int efm32_spi_remove(struct platform_device *pdev)
	{
	struct spi_master *master = platform_get_drvdata(pdev);
	struct efm32_spi_ddata *ddata = spi_master_get_devdata(master);

	spi_bitbang_stop(&ddata->bitbang);

	efm32_spi_write32(ddata, 0, REG_IEN);

	free_irq(ddata->txirq, ddata);
	free_irq(ddata->rxirq, ddata);
	clk_disable_unprepare(ddata->clk);
	spi_master_put(master);

	return 0;
	}

	static const struct of_device_id efm32_spi_dt_ids[] = {
	{
	.compatible = "efm32,spi",
	}, {
	/* sentinel */
	}
	};
	MODULE_DEVICE_TABLE(of, efm32_spi_dt_ids);

	static struct platform_driver efm32_spi_driver = {
	.probe = efm32_spi_probe,
	.remove = efm32_spi_remove,

	.driver = {
	.name = DRIVER_NAME,
	.owner = THIS_MODULE,
	.of_match_table = efm32_spi_dt_ids,
	},
	};
	module_platform_driver(efm32_spi_driver);

	MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
	MODULE_DESCRIPTION("EFM32 SPI driver");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:" DRIVER_NAME);