spi: Add SPI master driver for DaVinci/DA8xx

This patch adds support for a SPI master driver for the
DaVinci series of SOCs

Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>
Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: Philby John <pjohn@in.mvista.com>
Signed-off-by: Sudhakar Rajashekhara <sudhakar.raj@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

3 files changed, 1263 insertions, 0 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index f55eb0107336..82dabbca00c1 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -100,6 +100,13 @@ config SPI_BUTTERFLY
 	  inexpensive battery powered microcontroller evaluation board.
 	  This same cable can be used to flash new firmware.
 
+config SPI_DAVINCI
+	tristate "SPI controller driver for DaVinci/DA8xx SoC's"
+	depends on SPI_MASTER && ARCH_DAVINCI
+	select SPI_BITBANG
+	help
+	  SPI master controller for DaVinci and DA8xx SPI modules.
+
 config SPI_GPIO
 	tristate "GPIO-based bitbanging SPI Master"
 	depends on GENERIC_GPIO
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index f3d2810ba11c..84b490fb7f8a 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_SPI_BFIN)			+= spi_bfin5xx.o
 obj-$(CONFIG_SPI_BITBANG)		+= spi_bitbang.o
 obj-$(CONFIG_SPI_AU1550)		+= au1550_spi.o
 obj-$(CONFIG_SPI_BUTTERFLY)		+= spi_butterfly.o
+obj-$(CONFIG_SPI_DAVINCI)		+= davinci_spi.o
 obj-$(CONFIG_SPI_DESIGNWARE)		+= dw_spi.o
 obj-$(CONFIG_SPI_DW_PCI)		+= dw_spi_pci.o
 obj-$(CONFIG_SPI_GPIO)			+= spi_gpio.o
diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
new file mode 100644
index 000000000000..225ab60b02c4
--- /dev/null
+++ b/drivers/spi/davinci_spi.c
@@ -0,0 +1,1255 @@
+/*
+ * Copyright (C) 2009 Texas Instruments.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/gpio.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+
+#include <mach/spi.h>
+#include <mach/edma.h>
+
+#define SPI_NO_RESOURCE		((resource_size_t)-1)
+
+#define SPI_MAX_CHIPSELECT	2
+
+#define CS_DEFAULT	0xFF
+
+#define SPI_BUFSIZ	(SMP_CACHE_BYTES + 1)
+#define DAVINCI_DMA_DATA_TYPE_S8	0x01
+#define DAVINCI_DMA_DATA_TYPE_S16	0x02
+#define DAVINCI_DMA_DATA_TYPE_S32	0x04
+
+#define SPIFMT_PHASE_MASK	BIT(16)
+#define SPIFMT_POLARITY_MASK	BIT(17)
+#define SPIFMT_DISTIMER_MASK	BIT(18)
+#define SPIFMT_SHIFTDIR_MASK	BIT(20)
+#define SPIFMT_WAITENA_MASK	BIT(21)
+#define SPIFMT_PARITYENA_MASK	BIT(22)
+#define SPIFMT_ODD_PARITY_MASK	BIT(23)
+#define SPIFMT_WDELAY_MASK	0x3f000000u
+#define SPIFMT_WDELAY_SHIFT	24
+#define SPIFMT_CHARLEN_MASK	0x0000001Fu
+
+/* SPIGCR1 */
+#define SPIGCR1_SPIENA_MASK	0x01000000u
+
+/* SPIPC0 */
+#define SPIPC0_DIFUN_MASK	BIT(11)		/* MISO */
+#define SPIPC0_DOFUN_MASK	BIT(10)		/* MOSI */
+#define SPIPC0_CLKFUN_MASK	BIT(9)		/* CLK */
+#define SPIPC0_SPIENA_MASK	BIT(8)		/* nREADY */
+#define SPIPC0_EN1FUN_MASK	BIT(1)
+#define SPIPC0_EN0FUN_MASK	BIT(0)
+
+#define SPIINT_MASKALL		0x0101035F
+#define SPI_INTLVL_1		0x000001FFu
+#define SPI_INTLVL_0		0x00000000u
+
+/* SPIDAT1 */
+#define SPIDAT1_CSHOLD_SHIFT	28
+#define SPIDAT1_CSNR_SHIFT	16
+#define SPIGCR1_CLKMOD_MASK	BIT(1)
+#define SPIGCR1_MASTER_MASK     BIT(0)
+#define SPIGCR1_LOOPBACK_MASK	BIT(16)
+
+/* SPIBUF */
+#define SPIBUF_TXFULL_MASK	BIT(29)
+#define SPIBUF_RXEMPTY_MASK	BIT(31)
+
+/* Error Masks */
+#define SPIFLG_DLEN_ERR_MASK		BIT(0)
+#define SPIFLG_TIMEOUT_MASK		BIT(1)
+#define SPIFLG_PARERR_MASK		BIT(2)
+#define SPIFLG_DESYNC_MASK		BIT(3)
+#define SPIFLG_BITERR_MASK		BIT(4)
+#define SPIFLG_OVRRUN_MASK		BIT(6)
+#define SPIFLG_RX_INTR_MASK		BIT(8)
+#define SPIFLG_TX_INTR_MASK		BIT(9)
+#define SPIFLG_BUF_INIT_ACTIVE_MASK	BIT(24)
+#define SPIFLG_MASK			(SPIFLG_DLEN_ERR_MASK \
+				| SPIFLG_TIMEOUT_MASK | SPIFLG_PARERR_MASK \
+				| SPIFLG_DESYNC_MASK | SPIFLG_BITERR_MASK \
+				| SPIFLG_OVRRUN_MASK | SPIFLG_RX_INTR_MASK \
+				| SPIFLG_TX_INTR_MASK \
+				| SPIFLG_BUF_INIT_ACTIVE_MASK)
+
+#define SPIINT_DLEN_ERR_INTR	BIT(0)
+#define SPIINT_TIMEOUT_INTR	BIT(1)
+#define SPIINT_PARERR_INTR	BIT(2)
+#define SPIINT_DESYNC_INTR	BIT(3)
+#define SPIINT_BITERR_INTR	BIT(4)
+#define SPIINT_OVRRUN_INTR	BIT(6)
+#define SPIINT_RX_INTR		BIT(8)
+#define SPIINT_TX_INTR		BIT(9)
+#define SPIINT_DMA_REQ_EN	BIT(16)
+#define SPIINT_ENABLE_HIGHZ	BIT(24)
+
+#define SPI_T2CDELAY_SHIFT	16
+#define SPI_C2TDELAY_SHIFT	24
+
+/* SPI Controller registers */
+#define SPIGCR0		0x00
+#define SPIGCR1		0x04
+#define SPIINT		0x08
+#define SPILVL		0x0c
+#define SPIFLG		0x10
+#define SPIPC0		0x14
+#define SPIPC1		0x18
+#define SPIPC2		0x1c
+#define SPIPC3		0x20
+#define SPIPC4		0x24
+#define SPIPC5		0x28
+#define SPIPC6		0x2c
+#define SPIPC7		0x30
+#define SPIPC8		0x34
+#define SPIDAT0		0x38
+#define SPIDAT1		0x3c
+#define SPIBUF		0x40
+#define SPIEMU		0x44
+#define SPIDELAY	0x48
+#define SPIDEF		0x4c
+#define SPIFMT0		0x50
+#define SPIFMT1		0x54
+#define SPIFMT2		0x58
+#define SPIFMT3		0x5c
+#define TGINTVEC0	0x60
+#define TGINTVEC1	0x64
+
+struct davinci_spi_slave {
+	u32	cmd_to_write;
+	u32	clk_ctrl_to_write;
+	u32	bytes_per_word;
+	u8	active_cs;
+};
+
+/* We have 2 DMA channels per CS, one for RX and one for TX */
+struct davinci_spi_dma {
+	int			dma_tx_channel;
+	int			dma_rx_channel;
+	int			dma_tx_sync_dev;
+	int			dma_rx_sync_dev;
+	enum dma_event_q	eventq;
+
+	struct completion	dma_tx_completion;
+	struct completion	dma_rx_completion;
+};
+
+/* SPI Controller driver's private data. */
+struct davinci_spi {
+	struct spi_bitbang	bitbang;
+	struct clk		*clk;
+
+	u8			version;
+	resource_size_t		pbase;
+	void __iomem		*base;
+	size_t			region_size;
+	u32			irq;
+	struct completion	done;
+
+	const void		*tx;
+	void			*rx;
+	u8			*tmp_buf;
+	int			count;
+	struct davinci_spi_dma	*dma_channels;
+	struct			davinci_spi_platform_data *pdata;
+
+	void			(*get_rx)(u32 rx_data, struct davinci_spi *);
+	u32			(*get_tx)(struct davinci_spi *);
+
+	struct davinci_spi_slave slave[SPI_MAX_CHIPSELECT];
+};
+
+static unsigned use_dma;
+
+static void davinci_spi_rx_buf_u8(u32 data, struct davinci_spi *davinci_spi)
+{
+	u8 *rx = davinci_spi->rx;
+
+	*rx++ = (u8)data;
+	davinci_spi->rx = rx;
+}
+
+static void davinci_spi_rx_buf_u16(u32 data, struct davinci_spi *davinci_spi)
+{
+	u16 *rx = davinci_spi->rx;
+
+	*rx++ = (u16)data;
+	davinci_spi->rx = rx;
+}
+
+static u32 davinci_spi_tx_buf_u8(struct davinci_spi *davinci_spi)
+{
+	u32 data;
+	const u8 *tx = davinci_spi->tx;
+
+	data = *tx++;
+	davinci_spi->tx = tx;
+	return data;
+}
+
+static u32 davinci_spi_tx_buf_u16(struct davinci_spi *davinci_spi)
+{
+	u32 data;
+	const u16 *tx = davinci_spi->tx;
+
+	data = *tx++;
+	davinci_spi->tx = tx;
+	return data;
+}
+
+static inline void set_io_bits(void __iomem *addr, u32 bits)
+{
+	u32 v = ioread32(addr);
+
+	v |= bits;
+	iowrite32(v, addr);
+}
+
+static inline void clear_io_bits(void __iomem *addr, u32 bits)
+{
+	u32 v = ioread32(addr);
+
+	v &= ~bits;
+	iowrite32(v, addr);
+}
+
+static inline void set_fmt_bits(void __iomem *addr, u32 bits, int cs_num)
+{
+	set_io_bits(addr + SPIFMT0 + (0x4 * cs_num), bits);
+}
+
+static inline void clear_fmt_bits(void __iomem *addr, u32 bits, int cs_num)
+{
+	clear_io_bits(addr + SPIFMT0 + (0x4 * cs_num), bits);
+}
+
+static void davinci_spi_set_dma_req(const struct spi_device *spi, int enable)
+{
+	struct davinci_spi *davinci_spi = spi_master_get_devdata(spi->master);
+
+	if (enable)
+		set_io_bits(davinci_spi->base + SPIINT, SPIINT_DMA_REQ_EN);
+	else
+		clear_io_bits(davinci_spi->base + SPIINT, SPIINT_DMA_REQ_EN);
+}
+
+/*
+ * Interface to control the chip select signal
+ */
+static void davinci_spi_chipselect(struct spi_device *spi, int value)
+{
+	struct davinci_spi *davinci_spi;
+	struct davinci_spi_platform_data *pdata;
+	u32 data1_reg_val = 0;
+
+	davinci_spi = spi_master_get_devdata(spi->master);
+	pdata = davinci_spi->pdata;
+
+	/*
+	 * Board specific chip select logic decides the polarity and cs
+	 * line for the controller
+	 */
+	if (value == BITBANG_CS_INACTIVE) {
+		set_io_bits(davinci_spi->base + SPIDEF, CS_DEFAULT);
+
+		data1_reg_val |= CS_DEFAULT << SPIDAT1_CSNR_SHIFT;
+		iowrite32(data1_reg_val, davinci_spi->base + SPIDAT1);
+
+		while ((ioread32(davinci_spi->base + SPIBUF)
+					& SPIBUF_RXEMPTY_MASK) == 0)
+			cpu_relax();
+	}
+}
+
+/**
+ * davinci_spi_setup_transfer - This functions will determine transfer method
+ * @spi: spi device on which data transfer to be done
+ * @t: spi transfer in which transfer info is filled
+ *
+ * This function determines data transfer method (8/16/32 bit transfer).
+ * It will also set the SPI Clock Control register according to
+ * SPI slave device freq.
+ */
+static int davinci_spi_setup_transfer(struct spi_device *spi,
+		struct spi_transfer *t)
+{
+
+	struct davinci_spi *davinci_spi;
+	struct davinci_spi_platform_data *pdata;
+	u8 bits_per_word = 0;
+	u32 hz = 0, prescale;
+
+	davinci_spi = spi_master_get_devdata(spi->master);
+	pdata = davinci_spi->pdata;
+
+	if (t) {
+		bits_per_word = t->bits_per_word;
+		hz = t->speed_hz;
+	}
+
+	/* if bits_per_word is not set then set it default */
+	if (!bits_per_word)
+		bits_per_word = spi->bits_per_word;
+
+	/*
+	 * Assign function pointer to appropriate transfer method
+	 * 8bit, 16bit or 32bit transfer
+	 */
+	if (bits_per_word <= 8 && bits_per_word >= 2) {
+		davinci_spi->get_rx = davinci_spi_rx_buf_u8;
+		davinci_spi->get_tx = davinci_spi_tx_buf_u8;
+		davinci_spi->slave[spi->chip_select].bytes_per_word = 1;
+	} else if (bits_per_word <= 16 && bits_per_word >= 2) {
+		davinci_spi->get_rx = davinci_spi_rx_buf_u16;
+		davinci_spi->get_tx = davinci_spi_tx_buf_u16;
+		davinci_spi->slave[spi->chip_select].bytes_per_word = 2;
+	} else
+		return -EINVAL;
+
+	if (!hz)
+		hz = spi->max_speed_hz;
+
+	clear_fmt_bits(davinci_spi->base, SPIFMT_CHARLEN_MASK,
+			spi->chip_select);
+	set_fmt_bits(davinci_spi->base, bits_per_word & 0x1f,
+			spi->chip_select);
+
+	prescale = ((clk_get_rate(davinci_spi->clk) / hz) - 1) & 0xff;
+
+	clear_fmt_bits(davinci_spi->base, 0x0000ff00, spi->chip_select);
+	set_fmt_bits(davinci_spi->base, prescale << 8, spi->chip_select);
+
+	return 0;
+}
+
+static void davinci_spi_dma_rx_callback(unsigned lch, u16 ch_status, void *data)
+{
+	struct spi_device *spi = (struct spi_device *)data;
+	struct davinci_spi *davinci_spi;
+	struct davinci_spi_dma *davinci_spi_dma;
+	struct davinci_spi_platform_data *pdata;
+
+	davinci_spi = spi_master_get_devdata(spi->master);
+	davinci_spi_dma = &(davinci_spi->dma_channels[spi->chip_select]);
+	pdata = davinci_spi->pdata;
+
+	if (ch_status == DMA_COMPLETE)
+		edma_stop(davinci_spi_dma->dma_rx_channel);
+	else
+		edma_clean_channel(davinci_spi_dma->dma_rx_channel);
+
+	complete(&davinci_spi_dma->dma_rx_completion);
+	/* We must disable the DMA RX request */
+	davinci_spi_set_dma_req(spi, 0);
+}
+
+static void davinci_spi_dma_tx_callback(unsigned lch, u16 ch_status, void *data)
+{
+	struct spi_device *spi = (struct spi_device *)data;
+	struct davinci_spi *davinci_spi;
+	struct davinci_spi_dma *davinci_spi_dma;
+	struct davinci_spi_platform_data *pdata;
+
+	davinci_spi = spi_master_get_devdata(spi->master);
+	davinci_spi_dma = &(davinci_spi->dma_channels[spi->chip_select]);
+	pdata = davinci_spi->pdata;
+
+	if (ch_status == DMA_COMPLETE)
+		edma_stop(davinci_spi_dma->dma_tx_channel);
+	else
+		edma_clean_channel(davinci_spi_dma->dma_tx_channel);
+
+	complete(&davinci_spi_dma->dma_tx_completion);
+	/* We must disable the DMA TX request */
+	davinci_spi_set_dma_req(spi, 0);
+}
+
+static int davinci_spi_request_dma(struct spi_device *spi)
+{
+	struct davinci_spi *davinci_spi;
+	struct davinci_spi_dma *davinci_spi_dma;
+	struct davinci_spi_platform_data *pdata;
+	struct device *sdev;
+	int r;
+
+	davinci_spi = spi_master_get_devdata(spi->master);
+	davinci_spi_dma = &davinci_spi->dma_channels[spi->chip_select];
+	pdata = davinci_spi->pdata;
+	sdev = davinci_spi->bitbang.master->dev.parent;
+
+	r = edma_alloc_channel(davinci_spi_dma->dma_rx_sync_dev,
+				davinci_spi_dma_rx_callback, spi,
+				davinci_spi_dma->eventq);
+	if (r < 0) {
+		dev_dbg(sdev, "Unable to request DMA channel for SPI RX\n");
+		return -EAGAIN;
+	}
+	davinci_spi_dma->dma_rx_channel = r;
+	r = edma_alloc_channel(davinci_spi_dma->dma_tx_sync_dev,
+				davinci_spi_dma_tx_callback, spi,
+				davinci_spi_dma->eventq);
+	if (r < 0) {
+		edma_free_channel(davinci_spi_dma->dma_rx_channel);
+		davinci_spi_dma->dma_rx_channel = -1;
+		dev_dbg(sdev, "Unable to request DMA channel for SPI TX\n");
+		return -EAGAIN;
+	}
+	davinci_spi_dma->dma_tx_channel = r;
+
+	return 0;
+}
+
+/**
+ * davinci_spi_setup - This functions will set default transfer method
+ * @spi: spi device on which data transfer to be done
+ *
+ * This functions sets the default transfer method.
+ */
+
+static int davinci_spi_setup(struct spi_device *spi)
+{
+	int retval;
+	struct davinci_spi *davinci_spi;
+	struct davinci_spi_dma *davinci_spi_dma;
+	struct device *sdev;
+
+	davinci_spi = spi_master_get_devdata(spi->master);
+	sdev = davinci_spi->bitbang.master->dev.parent;
+
+	/* if bits per word length is zero then set it default 8 */
+	if (!spi->bits_per_word)
+		spi->bits_per_word = 8;
+
+	davinci_spi->slave[spi->chip_select].cmd_to_write = 0;
+
+	if (use_dma && davinci_spi->dma_channels) {
+		davinci_spi_dma = &davinci_spi->dma_channels[spi->chip_select];
+
+		if ((davinci_spi_dma->dma_rx_channel == -1)
+				|| (davinci_spi_dma->dma_tx_channel == -1)) {
+			retval = davinci_spi_request_dma(spi);
+			if (retval < 0)
+				return retval;
+		}
+	}
+
+	/*
+	 * SPI in DaVinci and DA8xx operate between
+	 * 600 KHz and 50 MHz
+	 */
+	if (spi->max_speed_hz < 600000 || spi->max_speed_hz > 50000000) {
+		dev_dbg(sdev, "Operating frequency is not in acceptable "
+				"range\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Set up SPIFMTn register, unique to this chipselect.
+	 *
+	 * NOTE: we could do all of these with one write.  Also, some
+	 * of the "version 2" features are found in chips that don't
+	 * support all of them...
+	 */
+	if (spi->mode & SPI_LSB_FIRST)
+		set_fmt_bits(davinci_spi->base, SPIFMT_SHIFTDIR_MASK,
+				spi->chip_select);
+	else
+		clear_fmt_bits(davinci_spi->base, SPIFMT_SHIFTDIR_MASK,
+				spi->chip_select);
+
+	if (spi->mode & SPI_CPOL)
+		set_fmt_bits(davinci_spi->base, SPIFMT_POLARITY_MASK,
+				spi->chip_select);
+	else
+		clear_fmt_bits(davinci_spi->base, SPIFMT_POLARITY_MASK,
+				spi->chip_select);
+
+	if (!(spi->mode & SPI_CPHA))
+		set_fmt_bits(davinci_spi->base, SPIFMT_PHASE_MASK,
+				spi->chip_select);
+	else
+		clear_fmt_bits(davinci_spi->base, SPIFMT_PHASE_MASK,
+				spi->chip_select);
+
+	/*
+	 * Version 1 hardware supports two basic SPI modes:
+	 *  - Standard SPI mode uses 4 pins, with chipselect
+	 *  - 3 pin SPI is a 4 pin variant without CS (SPI_NO_CS)
+	 *	(distinct from SPI_3WIRE, with just one data wire;
+	 *	or similar variants without MOSI or without MISO)
+	 *
+	 * Version 2 hardware supports an optional handshaking signal,
+	 * so it can support two more modes:
+	 *  - 5 pin SPI variant is standard SPI plus SPI_READY
+	 *  - 4 pin with enable is (SPI_READY | SPI_NO_CS)
+	 */
+
+	if (davinci_spi->version == SPI_VERSION_2) {
+		clear_fmt_bits(davinci_spi->base, SPIFMT_WDELAY_MASK,
+				spi->chip_select);
+		set_fmt_bits(davinci_spi->base,
+				(davinci_spi->pdata->wdelay
+						<< SPIFMT_WDELAY_SHIFT)
+					& SPIFMT_WDELAY_MASK,
+				spi->chip_select);
+
+		if (davinci_spi->pdata->odd_parity)
+			set_fmt_bits(davinci_spi->base,
+					SPIFMT_ODD_PARITY_MASK,
+					spi->chip_select);
+		else
+			clear_fmt_bits(davinci_spi->base,
+					SPIFMT_ODD_PARITY_MASK,
+					spi->chip_select);
+
+		if (davinci_spi->pdata->parity_enable)
+			set_fmt_bits(davinci_spi->base,
+					SPIFMT_PARITYENA_MASK,
+					spi->chip_select);
+		else
+			clear_fmt_bits(davinci_spi->base,
+					SPIFMT_PARITYENA_MASK,
+					spi->chip_select);
+
+		if (davinci_spi->pdata->wait_enable)
+			set_fmt_bits(davinci_spi->base,
+					SPIFMT_WAITENA_MASK,
+					spi->chip_select);
+		else
+			clear_fmt_bits(davinci_spi->base,
+					SPIFMT_WAITENA_MASK,
+					spi->chip_select);
+
+		if (davinci_spi->pdata->timer_disable)
+			set_fmt_bits(davinci_spi->base,
+					SPIFMT_DISTIMER_MASK,
+					spi->chip_select);
+		else
+			clear_fmt_bits(davinci_spi->base,
+					SPIFMT_DISTIMER_MASK,
+					spi->chip_select);
+	}
+
+	retval = davinci_spi_setup_transfer(spi, NULL);
+
+	return retval;
+}
+
+static void davinci_spi_cleanup(struct spi_device *spi)
+{
+	struct davinci_spi *davinci_spi = spi_master_get_devdata(spi->master);
+	struct davinci_spi_dma *davinci_spi_dma;
+
+	davinci_spi_dma = &davinci_spi->dma_channels[spi->chip_select];
+
+	if (use_dma && davinci_spi->dma_channels) {
+		davinci_spi_dma = &davinci_spi->dma_channels[spi->chip_select];
+
+		if ((davinci_spi_dma->dma_rx_channel != -1)
+				&& (davinci_spi_dma->dma_tx_channel != -1)) {
+			edma_free_channel(davinci_spi_dma->dma_tx_channel);
+			edma_free_channel(davinci_spi_dma->dma_rx_channel);
+		}
+	}
+}
+
+static int davinci_spi_bufs_prep(struct spi_device *spi,
+				 struct davinci_spi *davinci_spi)
+{
+	int op_mode = 0;
+
+	/*
+	 * REVISIT  unless devices disagree about SPI_LOOP or
+	 * SPI_READY (SPI_NO_CS only allows one device!), this
+	 * should not need to be done before each message...
+	 * optimize for both flags staying cleared.
+	 */
+
+	op_mode = SPIPC0_DIFUN_MASK
+		| SPIPC0_DOFUN_MASK
+		| SPIPC0_CLKFUN_MASK;
+	if (!(spi->mode & SPI_NO_CS))
+		op_mode |= 1 << spi->chip_select;
+	if (spi->mode & SPI_READY)
+		op_mode |= SPIPC0_SPIENA_MASK;
+
+	iowrite32(op_mode, davinci_spi->base + SPIPC0);
+
+	if (spi->mode & SPI_LOOP)
+		set_io_bits(davinci_spi->base + SPIGCR1,
+				SPIGCR1_LOOPBACK_MASK);
+	else
+		clear_io_bits(davinci_spi->base + SPIGCR1,
+				SPIGCR1_LOOPBACK_MASK);
+
+	return 0;
+}
+
+static int davinci_spi_check_error(struct davinci_spi *davinci_spi,
+				   int int_status)
+{
+	struct device *sdev = davinci_spi->bitbang.master->dev.parent;
+
+	if (int_status & SPIFLG_TIMEOUT_MASK) {
+		dev_dbg(sdev, "SPI Time-out Error\n");
+		return -ETIMEDOUT;
+	}
+	if (int_status & SPIFLG_DESYNC_MASK) {
+		dev_dbg(sdev, "SPI Desynchronization Error\n");
+		return -EIO;
+	}
+	if (int_status & SPIFLG_BITERR_MASK) {
+		dev_dbg(sdev, "SPI Bit error\n");
+		return -EIO;
+	}
+
+	if (davinci_spi->version == SPI_VERSION_2) {
+		if (int_status & SPIFLG_DLEN_ERR_MASK) {
+			dev_dbg(sdev, "SPI Data Length Error\n");
+			return -EIO;
+		}
+		if (int_status & SPIFLG_PARERR_MASK) {
+			dev_dbg(sdev, "SPI Parity Error\n");
+			return -EIO;
+		}
+		if (int_status & SPIFLG_OVRRUN_MASK) {
+			dev_dbg(sdev, "SPI Data Overrun error\n");
+			return -EIO;
+		}
+		if (int_status & SPIFLG_TX_INTR_MASK) {
+			dev_dbg(sdev, "SPI TX intr bit set\n");
+			return -EIO;
+		}
+		if (int_status & SPIFLG_BUF_INIT_ACTIVE_MASK) {
+			dev_dbg(sdev, "SPI Buffer Init Active\n");
+			return -EBUSY;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * davinci_spi_bufs - functions which will handle transfer data
+ * @spi: spi device on which data transfer to be done
+ * @t: spi transfer in which transfer info is filled
+ *
+ * This function will put data to be transferred into data register
+ * of SPI controller and then wait until the completion will be marked
+ * by the IRQ Handler.
+ */
+static int davinci_spi_bufs_pio(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct davinci_spi *davinci_spi;
+	int int_status, count, ret;
+	u8 conv, tmp;
+	u32 tx_data, data1_reg_val;
+	u32 buf_val, flg_val;
+	struct davinci_spi_platform_data *pdata;
+
+	davinci_spi = spi_master_get_devdata(spi->master);
+	pdata = davinci_spi->pdata;
+
+	davinci_spi->tx = t->tx_buf;
+	davinci_spi->rx = t->rx_buf;
+
+	/* convert len to words based on bits_per_word */
+	conv = davinci_spi->slave[spi->chip_select].bytes_per_word;
+	davinci_spi->count = t->len / conv;
+
+	INIT_COMPLETION(davinci_spi->done);
+
+	ret = davinci_spi_bufs_prep(spi, davinci_spi);
+	if (ret)
+		return ret;
+
+	/* Enable SPI */
+	set_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
+
+	iowrite32(0 | (pdata->c2tdelay << SPI_C2TDELAY_SHIFT) |
+			(pdata->t2cdelay << SPI_T2CDELAY_SHIFT),
+			davinci_spi->base + SPIDELAY);
+
+	count = davinci_spi->count;
+	data1_reg_val = pdata->cs_hold << SPIDAT1_CSHOLD_SHIFT;
+	tmp = ~(0x1 << spi->chip_select);
+
+	clear_io_bits(davinci_spi->base + SPIDEF, ~tmp);
+
+	data1_reg_val |= tmp << SPIDAT1_CSNR_SHIFT;
+
+	while ((ioread32(davinci_spi->base + SPIBUF)
+				& SPIBUF_RXEMPTY_MASK) == 0)
+		cpu_relax();
+
+	/* Determine the command to execute READ or WRITE */
+	if (t->tx_buf) {
+		clear_io_bits(davinci_spi->base + SPIINT, SPIINT_MASKALL);
+
+		while (1) {
+			tx_data = davinci_spi->get_tx(davinci_spi);
+
+			data1_reg_val &= ~(0xFFFF);
+			data1_reg_val |= (0xFFFF & tx_data);
+
+			buf_val = ioread32(davinci_spi->base + SPIBUF);
+			if ((buf_val & SPIBUF_TXFULL_MASK) == 0) {
+				iowrite32(data1_reg_val,
+						davinci_spi->base + SPIDAT1);
+
+				count--;
+			}
+			while (ioread32(davinci_spi->base + SPIBUF)
+					& SPIBUF_RXEMPTY_MASK)
+				cpu_relax();
+
+			/* getting the returned byte */
+			if (t->rx_buf) {
+				buf_val = ioread32(davinci_spi->base + SPIBUF);
+				davinci_spi->get_rx(buf_val, davinci_spi);
+			}
+			if (count <= 0)
+				break;
+		}
+	} else {
+		if (pdata->poll_mode) {
+			while (1) {
+				/* keeps the serial clock going */
+				if ((ioread32(davinci_spi->base + SPIBUF)
+						& SPIBUF_TXFULL_MASK) == 0)
+					iowrite32(data1_reg_val,
+						davinci_spi->base + SPIDAT1);
+
+				while (ioread32(davinci_spi->base + SPIBUF) &
+						SPIBUF_RXEMPTY_MASK)
+					cpu_relax();
+
+				flg_val = ioread32(davinci_spi->base + SPIFLG);
+				buf_val = ioread32(davinci_spi->base + SPIBUF);
+
+				davinci_spi->get_rx(buf_val, davinci_spi);
+
+				count--;
+				if (count <= 0)
+					break;
+			}
+		} else {	/* Receive in Interrupt mode */
+			int i;
+
+			for (i = 0; i < davinci_spi->count; i++) {
+				set_io_bits(davinci_spi->base + SPIINT,
+						SPIINT_BITERR_INTR
+						| SPIINT_OVRRUN_INTR
+						| SPIINT_RX_INTR);
+
+				iowrite32(data1_reg_val,
+						davinci_spi->base + SPIDAT1);
+
+				while (ioread32(davinci_spi->base + SPIINT) &
+						SPIINT_RX_INTR)
+					cpu_relax();
+			}
+			iowrite32((data1_reg_val & 0x0ffcffff),
+					davinci_spi->base + SPIDAT1);
+		}
+	}
+
+	/*
+	 * Check for bit error, desync error,parity error,timeout error and
+	 * receive overflow errors
+	 */
+	int_status = ioread32(davinci_spi->base + SPIFLG);
+
+	ret = davinci_spi_check_error(davinci_spi, int_status);
+	if (ret != 0)
+		return ret;
+
+	/* SPI Framework maintains the count only in bytes so convert back */
+	davinci_spi->count *= conv;
+
+	return t->len;
+}
+
+#define DAVINCI_DMA_DATA_TYPE_S8	0x01
+#define DAVINCI_DMA_DATA_TYPE_S16	0x02
+#define DAVINCI_DMA_DATA_TYPE_S32	0x04
+
+static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct davinci_spi *davinci_spi;
+	int int_status = 0;
+	int count, temp_count;
+	u8 conv = 1;
+	u8 tmp;
+	u32 data1_reg_val;
+	struct davinci_spi_dma *davinci_spi_dma;
+	int word_len, data_type, ret;
+	unsigned long tx_reg, rx_reg;
+	struct davinci_spi_platform_data *pdata;
+	struct device *sdev;
+
+	davinci_spi = spi_master_get_devdata(spi->master);
+	pdata = davinci_spi->pdata;
+	sdev = davinci_spi->bitbang.master->dev.parent;
+
+	davinci_spi_dma = &davinci_spi->dma_channels[spi->chip_select];
+
+	tx_reg = (unsigned long)davinci_spi->pbase + SPIDAT1;
+	rx_reg = (unsigned long)davinci_spi->pbase + SPIBUF;
+
+	davinci_spi->tx = t->tx_buf;
+	davinci_spi->rx = t->rx_buf;
+
+	/* convert len to words based on bits_per_word */
+	conv = davinci_spi->slave[spi->chip_select].bytes_per_word;
+	davinci_spi->count = t->len / conv;
+
+	INIT_COMPLETION(davinci_spi->done);
+
+	init_completion(&davinci_spi_dma->dma_rx_completion);
+	init_completion(&davinci_spi_dma->dma_tx_completion);
+
+	word_len = conv * 8;
+
+	if (word_len <= 8)
+		data_type = DAVINCI_DMA_DATA_TYPE_S8;
+	else if (word_len <= 16)
+		data_type = DAVINCI_DMA_DATA_TYPE_S16;
+	else if (word_len <= 32)
+		data_type = DAVINCI_DMA_DATA_TYPE_S32;
+	else
+		return -EINVAL;
+
+	ret = davinci_spi_bufs_prep(spi, davinci_spi);
+	if (ret)
+		return ret;
+
+	/* Put delay val if required */
+	iowrite32(0 | (pdata->c2tdelay << SPI_C2TDELAY_SHIFT) |
+			(pdata->t2cdelay << SPI_T2CDELAY_SHIFT),
+			davinci_spi->base + SPIDELAY);
+
+	count = davinci_spi->count;	/* the number of elements */
+	data1_reg_val = pdata->cs_hold << SPIDAT1_CSHOLD_SHIFT;
+
+	/* CS default = 0xFF */
+	tmp = ~(0x1 << spi->chip_select);
+
+	clear_io_bits(davinci_spi->base + SPIDEF, ~tmp);
+
+	data1_reg_val |= tmp << SPIDAT1_CSNR_SHIFT;
+
+	/* disable all interrupts for dma transfers */
+	clear_io_bits(davinci_spi->base + SPIINT, SPIINT_MASKALL);
+	/* Disable SPI to write configuration bits in SPIDAT */
+	clear_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
+	iowrite32(data1_reg_val, davinci_spi->base + SPIDAT1);
+	/* Enable SPI */
+	set_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
+
+	while ((ioread32(davinci_spi->base + SPIBUF)
+				& SPIBUF_RXEMPTY_MASK) == 0)
+		cpu_relax();
+
+
+	if (t->tx_buf) {
+		t->tx_dma = dma_map_single(&spi->dev, (void *)t->tx_buf, count,
+				DMA_TO_DEVICE);
+		if (dma_mapping_error(&spi->dev, t->tx_dma)) {
+			dev_dbg(sdev, "Unable to DMA map a %d bytes"
+				" TX buffer\n", count);
+			return -ENOMEM;
+		}
+		temp_count = count;
+	} else {
+		/* We need TX clocking for RX transaction */
+		t->tx_dma = dma_map_single(&spi->dev,
+				(void *)davinci_spi->tmp_buf, count + 1,
+				DMA_TO_DEVICE);
+		if (dma_mapping_error(&spi->dev, t->tx_dma)) {
+			dev_dbg(sdev, "Unable to DMA map a %d bytes"
+				" TX tmp buffer\n", count);
+			return -ENOMEM;
+		}
+		temp_count = count + 1;
+	}
+
+	edma_set_transfer_params(davinci_spi_dma->dma_tx_channel,
+					data_type, temp_count, 1, 0, ASYNC);
+	edma_set_dest(davinci_spi_dma->dma_tx_channel, tx_reg, INCR, W8BIT);
+	edma_set_src(davinci_spi_dma->dma_tx_channel, t->tx_dma, INCR, W8BIT);
+	edma_set_src_index(davinci_spi_dma->dma_tx_channel, data_type, 0);
+	edma_set_dest_index(davinci_spi_dma->dma_tx_channel, 0, 0);
+
+	if (t->rx_buf) {
+		/* initiate transaction */
+		iowrite32(data1_reg_val, davinci_spi->base + SPIDAT1);
+
+		t->rx_dma = dma_map_single(&spi->dev, (void *)t->rx_buf, count,
+				DMA_FROM_DEVICE);
+		if (dma_mapping_error(&spi->dev, t->rx_dma)) {
+			dev_dbg(sdev, "Couldn't DMA map a %d bytes RX buffer\n",
+					count);
+			if (t->tx_buf != NULL)
+				dma_unmap_single(NULL, t->tx_dma,
+						 count, DMA_TO_DEVICE);
+			return -ENOMEM;
+		}
+		edma_set_transfer_params(davinci_spi_dma->dma_rx_channel,
+				data_type, count, 1, 0, ASYNC);
+		edma_set_src(davinci_spi_dma->dma_rx_channel,
+				rx_reg, INCR, W8BIT);
+		edma_set_dest(davinci_spi_dma->dma_rx_channel,
+				t->rx_dma, INCR, W8BIT);
+		edma_set_src_index(davinci_spi_dma->dma_rx_channel, 0, 0);
+		edma_set_dest_index(davinci_spi_dma->dma_rx_channel,
+				data_type, 0);
+	}
+
+	if ((t->tx_buf) || (t->rx_buf))
+		edma_start(davinci_spi_dma->dma_tx_channel);
+
+	if (t->rx_buf)
+		edma_start(davinci_spi_dma->dma_rx_channel);
+
+	if ((t->rx_buf) || (t->tx_buf))
+		davinci_spi_set_dma_req(spi, 1);
+
+	if (t->tx_buf)
+		wait_for_completion_interruptible(
+				&davinci_spi_dma->dma_tx_completion);
+
+	if (t->rx_buf)
+		wait_for_completion_interruptible(
+				&davinci_spi_dma->dma_rx_completion);
+
+	dma_unmap_single(NULL, t->tx_dma, temp_count, DMA_TO_DEVICE);
+
+	if (t->rx_buf)
+		dma_unmap_single(NULL, t->rx_dma, count, DMA_FROM_DEVICE);
+
+	/*
+	 * Check for bit error, desync error,parity error,timeout error and
+	 * receive overflow errors
+	 */
+	int_status = ioread32(davinci_spi->base + SPIFLG);
+
+	ret = davinci_spi_check_error(davinci_spi, int_status);
+	if (ret != 0)
+		return ret;
+
+	/* SPI Framework maintains the count only in bytes so convert back */
+	davinci_spi->count *= conv;
+
+	return t->len;
+}
+
+/**
+ * davinci_spi_irq - IRQ handler for DaVinci SPI
+ * @irq: IRQ number for this SPI Master
+ * @context_data: structure for SPI Master controller davinci_spi
+ */
+static irqreturn_t davinci_spi_irq(s32 irq, void *context_data)
+{
+	struct davinci_spi *davinci_spi = context_data;
+	u32 int_status, rx_data = 0;
+	irqreturn_t ret = IRQ_NONE;
+
+	int_status = ioread32(davinci_spi->base + SPIFLG);
+
+	while ((int_status & SPIFLG_RX_INTR_MASK)) {
+		if (likely(int_status & SPIFLG_RX_INTR_MASK)) {
+			ret = IRQ_HANDLED;
+
+			rx_data = ioread32(davinci_spi->base + SPIBUF);
+			davinci_spi->get_rx(rx_data, davinci_spi);
+
+			/* Disable Receive Interrupt */
+			iowrite32(~(SPIINT_RX_INTR | SPIINT_TX_INTR),
+					davinci_spi->base + SPIINT);
+		} else
+			(void)davinci_spi_check_error(davinci_spi, int_status);
+
+		int_status = ioread32(davinci_spi->base + SPIFLG);
+	}
+
+	return ret;
+}
+
+/**
+ * davinci_spi_probe - probe function for SPI Master Controller
+ * @pdev: platform_device structure which contains plateform specific data
+ */
+static int davinci_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct davinci_spi *davinci_spi;
+	struct davinci_spi_platform_data *pdata;
+	struct resource *r, *mem;
+	resource_size_t dma_rx_chan = SPI_NO_RESOURCE;
+	resource_size_t	dma_tx_chan = SPI_NO_RESOURCE;
+	resource_size_t	dma_eventq = SPI_NO_RESOURCE;
+	int i = 0, ret = 0;
+
+	pdata = pdev->dev.platform_data;
+	if (pdata == NULL) {
+		ret = -ENODEV;
+		goto err;
+	}
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct davinci_spi));
+	if (master == NULL) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	dev_set_drvdata(&pdev->dev, master);
+
+	davinci_spi = spi_master_get_devdata(master);
+	if (davinci_spi == NULL) {
+		ret = -ENOENT;
+		goto free_master;
+	}
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		ret = -ENOENT;
+		goto free_master;
+	}
+
+	davinci_spi->pbase = r->start;
+	davinci_spi->region_size = resource_size(r);
+	davinci_spi->pdata = pdata;
+
+	mem = request_mem_region(r->start, davinci_spi->region_size,
+					pdev->name);
+	if (mem == NULL) {
+		ret = -EBUSY;
+		goto free_master;
+	}
+
+	davinci_spi->base = (struct davinci_spi_reg __iomem *)
+			ioremap(r->start, davinci_spi->region_size);
+	if (davinci_spi->base == NULL) {
+		ret = -ENOMEM;
+		goto release_region;
+	}
+
+	davinci_spi->irq = platform_get_irq(pdev, 0);
+	if (davinci_spi->irq <= 0) {
+		ret = -EINVAL;
+		goto unmap_io;
+	}
+
+	ret = request_irq(davinci_spi->irq, davinci_spi_irq, IRQF_DISABLED,
+			  dev_name(&pdev->dev), davinci_spi);
+	if (ret)
+		goto unmap_io;
+
+	/* Allocate tmp_buf for tx_buf */
+	davinci_spi->tmp_buf = kzalloc(SPI_BUFSIZ, GFP_KERNEL);
+	if (davinci_spi->tmp_buf == NULL) {
+		ret = -ENOMEM;
+		goto irq_free;
+	}
+
+	davinci_spi->bitbang.master = spi_master_get(master);
+	if (davinci_spi->bitbang.master == NULL) {
+		ret = -ENODEV;
+		goto free_tmp_buf;
+	}
+
+	davinci_spi->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(davinci_spi->clk)) {
+		ret = -ENODEV;
+		goto put_master;
+	}
+	clk_enable(davinci_spi->clk);
+
+
+	master->bus_num = pdev->id;
+	master->num_chipselect = pdata->num_chipselect;
+	master->setup = davinci_spi_setup;
+	master->cleanup = davinci_spi_cleanup;
+
+	davinci_spi->bitbang.chipselect = davinci_spi_chipselect;
+	davinci_spi->bitbang.setup_transfer = davinci_spi_setup_transfer;
+
+	davinci_spi->version = pdata->version;
+	use_dma = pdata->use_dma;
+
+	davinci_spi->bitbang.flags = SPI_NO_CS | SPI_LSB_FIRST | SPI_LOOP;
+	if (davinci_spi->version == SPI_VERSION_2)
+		davinci_spi->bitbang.flags |= SPI_READY;
+
+	if (use_dma) {
+			r = platform_get_resource(pdev, IORESOURCE_DMA, 0);
+			if (r)
+				dma_rx_chan = r->start;
+			r = platform_get_resource(pdev, IORESOURCE_DMA, 1);
+			if (r)
+				dma_tx_chan = r->start;
+			r = platform_get_resource(pdev, IORESOURCE_DMA, 2);
+			if (r)
+				dma_eventq = r->start;
+	}
+
+	if (!use_dma ||
+	    dma_rx_chan == SPI_NO_RESOURCE ||
+	    dma_tx_chan == SPI_NO_RESOURCE ||
+	    dma_eventq	== SPI_NO_RESOURCE) {
+		davinci_spi->bitbang.txrx_bufs = davinci_spi_bufs_pio;
+		use_dma = 0;
+	} else {
+		davinci_spi->bitbang.txrx_bufs = davinci_spi_bufs_dma;
+		davinci_spi->dma_channels = kzalloc(master->num_chipselect
+				* sizeof(struct davinci_spi_dma), GFP_KERNEL);
+		if (davinci_spi->dma_channels == NULL) {
+			ret = -ENOMEM;
+			goto free_clk;
+		}
+
+		for (i = 0; i < master->num_chipselect; i++) {
+			davinci_spi->dma_channels[i].dma_rx_channel = -1;
+			davinci_spi->dma_channels[i].dma_rx_sync_dev =
+				dma_rx_chan;
+			davinci_spi->dma_channels[i].dma_tx_channel = -1;
+			davinci_spi->dma_channels[i].dma_tx_sync_dev =
+				dma_tx_chan;
+			davinci_spi->dma_channels[i].eventq = dma_eventq;
+		}
+		dev_info(&pdev->dev, "DaVinci SPI driver in EDMA mode\n"
+				"Using RX channel = %d , TX channel = %d and "
+				"event queue = %d", dma_rx_chan, dma_tx_chan,
+				dma_eventq);
+	}
+
+	davinci_spi->get_rx = davinci_spi_rx_buf_u8;
+	davinci_spi->get_tx = davinci_spi_tx_buf_u8;
+
+	init_completion(&davinci_spi->done);
+
+	/* Reset In/OUT SPI module */
+	iowrite32(0, davinci_spi->base + SPIGCR0);
+	udelay(100);
+	iowrite32(1, davinci_spi->base + SPIGCR0);
+
+	/* Clock internal */
+	if (davinci_spi->pdata->clk_internal)
+		set_io_bits(davinci_spi->base + SPIGCR1,
+				SPIGCR1_CLKMOD_MASK);
+	else
+		clear_io_bits(davinci_spi->base + SPIGCR1,
+				SPIGCR1_CLKMOD_MASK);
+
+	/* master mode default */
+	set_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_MASTER_MASK);
+
+	if (davinci_spi->pdata->intr_level)
+		iowrite32(SPI_INTLVL_1, davinci_spi->base + SPILVL);
+	else
+		iowrite32(SPI_INTLVL_0, davinci_spi->base + SPILVL);
+
+	ret = spi_bitbang_start(&davinci_spi->bitbang);
+	if (ret)
+		goto free_clk;
+
+	dev_info(&pdev->dev, "Controller at 0x%p \n", davinci_spi->base);
+
+	if (!pdata->poll_mode)
+		dev_info(&pdev->dev, "Operating in interrupt mode"
+			" using IRQ %d\n", davinci_spi->irq);
+
+	return ret;
+
+free_clk:
+	clk_disable(davinci_spi->clk);
+	clk_put(davinci_spi->clk);
+put_master:
+	spi_master_put(master);
+free_tmp_buf:
+	kfree(davinci_spi->tmp_buf);
+irq_free:
+	free_irq(davinci_spi->irq, davinci_spi);
+unmap_io:
+	iounmap(davinci_spi->base);
+release_region:
+	release_mem_region(davinci_spi->pbase, davinci_spi->region_size);
+free_master:
+	kfree(master);
+err:
+	return ret;
+}
+
+/**
+ * davinci_spi_remove - remove function for SPI Master Controller
+ * @pdev: platform_device structure which contains plateform specific data
+ *
+ * This function will do the reverse action of davinci_spi_probe function
+ * It will free the IRQ and SPI controller's memory region.
+ * It will also call spi_bitbang_stop to destroy the work queue which was
+ * created by spi_bitbang_start.
+ */
+static int __exit davinci_spi_remove(struct platform_device *pdev)
+{
+	struct davinci_spi *davinci_spi;
+	struct spi_master *master;
+
+	master = dev_get_drvdata(&pdev->dev);
+	davinci_spi = spi_master_get_devdata(master);
+
+	spi_bitbang_stop(&davinci_spi->bitbang);
+
+	clk_disable(davinci_spi->clk);
+	clk_put(davinci_spi->clk);
+	spi_master_put(master);
+	kfree(davinci_spi->tmp_buf);
+	free_irq(davinci_spi->irq, davinci_spi);
+	iounmap(davinci_spi->base);
+	release_mem_region(davinci_spi->pbase, davinci_spi->region_size);
+
+	return 0;
+}
+
+static struct platform_driver davinci_spi_driver = {
+	.driver.name = "spi_davinci",
+	.remove = __exit_p(davinci_spi_remove),
+};
+
+static int __init davinci_spi_init(void)
+{
+	return platform_driver_probe(&davinci_spi_driver, davinci_spi_probe);
+}
+module_init(davinci_spi_init);
+
+static void __exit davinci_spi_exit(void)
+{
+	platform_driver_unregister(&davinci_spi_driver);
+}
+module_exit(davinci_spi_exit);
+
+MODULE_DESCRIPTION("TI DaVinci SPI Master Controller Driver");
+MODULE_LICENSE("GPL");