Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1110 insertions, 0 deletions

diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
new file mode 100644
index 000000000..b56038945
--- /dev/null
+++ b/drivers/spi/spi-davinci.c
@@ -0,0 +1,1110 @@
+/*
+ * Copyright (C) 2009 Texas Instruments.
+ * Copyright (C) 2010 EF Johnson Technologies
+ *
+ * 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.
+ */
+
+#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/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/slab.h>
+
+#include <linux/platform_data/spi-davinci.h>
+
+#define CS_DEFAULT	0xFF
+
+#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_PRESCALE_SHIFT	8
+
+/* 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 SPIINT_MASKALL		0x0101035F
+#define SPIINT_MASKINT		0x0000015F
+#define SPI_INTLVL_1		0x000001FF
+#define SPI_INTLVL_0		0x00000000
+
+/* SPIDAT1 (upper 16 bit defines) */
+#define SPIDAT1_CSHOLD_MASK	BIT(12)
+#define SPIDAT1_WDEL		BIT(10)
+
+/* SPIGCR1 */
+#define SPIGCR1_CLKMOD_MASK	BIT(1)
+#define SPIGCR1_MASTER_MASK     BIT(0)
+#define SPIGCR1_POWERDOWN_MASK	BIT(8)
+#define SPIGCR1_LOOPBACK_MASK	BIT(16)
+#define SPIGCR1_SPIENA_MASK	BIT(24)
+
+/* SPIBUF */
+#define SPIBUF_TXFULL_MASK	BIT(29)
+#define SPIBUF_RXEMPTY_MASK	BIT(31)
+
+/* SPIDELAY */
+#define SPIDELAY_C2TDELAY_SHIFT 24
+#define SPIDELAY_C2TDELAY_MASK  (0xFF << SPIDELAY_C2TDELAY_SHIFT)
+#define SPIDELAY_T2CDELAY_SHIFT 16
+#define SPIDELAY_T2CDELAY_MASK  (0xFF << SPIDELAY_T2CDELAY_SHIFT)
+#define SPIDELAY_T2EDELAY_SHIFT 8
+#define SPIDELAY_T2EDELAY_MASK  (0xFF << SPIDELAY_T2EDELAY_SHIFT)
+#define SPIDELAY_C2EDELAY_SHIFT 0
+#define SPIDELAY_C2EDELAY_MASK  0xFF
+
+/* 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_BUF_INIT_ACTIVE_MASK	BIT(24)
+#define SPIFLG_ERROR_MASK		(SPIFLG_DLEN_ERR_MASK \
+				| SPIFLG_TIMEOUT_MASK | SPIFLG_PARERR_MASK \
+				| SPIFLG_DESYNC_MASK | SPIFLG_BITERR_MASK \
+				| SPIFLG_OVRRUN_MASK)
+
+#define SPIINT_DMA_REQ_EN	BIT(16)
+
+/* SPI Controller registers */
+#define SPIGCR0		0x00
+#define SPIGCR1		0x04
+#define SPIINT		0x08
+#define SPILVL		0x0c
+#define SPIFLG		0x10
+#define SPIPC0		0x14
+#define SPIDAT1		0x3c
+#define SPIBUF		0x40
+#define SPIDELAY	0x48
+#define SPIDEF		0x4c
+#define SPIFMT0		0x50
+
+#define DMA_MIN_BYTES	16
+
+/* 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;
+	u32			irq;
+	struct completion	done;
+
+	const void		*tx;
+	void			*rx;
+	int			rcount;
+	int			wcount;
+
+	struct dma_chan		*dma_rx;
+	struct dma_chan		*dma_tx;
+
+	struct davinci_spi_platform_data pdata;
+
+	void			(*get_rx)(u32 rx_data, struct davinci_spi *);
+	u32			(*get_tx)(struct davinci_spi *);
+
+	u8			*bytes_per_word;
+
+	u8			prescaler_limit;
+};
+
+static struct davinci_spi_config davinci_spi_default_cfg;
+
+static void davinci_spi_rx_buf_u8(u32 data, struct davinci_spi *dspi)
+{
+	if (dspi->rx) {
+		u8 *rx = dspi->rx;
+		*rx++ = (u8)data;
+		dspi->rx = rx;
+	}
+}
+
+static void davinci_spi_rx_buf_u16(u32 data, struct davinci_spi *dspi)
+{
+	if (dspi->rx) {
+		u16 *rx = dspi->rx;
+		*rx++ = (u16)data;
+		dspi->rx = rx;
+	}
+}
+
+static u32 davinci_spi_tx_buf_u8(struct davinci_spi *dspi)
+{
+	u32 data = 0;
+
+	if (dspi->tx) {
+		const u8 *tx = dspi->tx;
+
+		data = *tx++;
+		dspi->tx = tx;
+	}
+	return data;
+}
+
+static u32 davinci_spi_tx_buf_u16(struct davinci_spi *dspi)
+{
+	u32 data = 0;
+
+	if (dspi->tx) {
+		const u16 *tx = dspi->tx;
+
+		data = *tx++;
+		dspi->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);
+}
+
+/*
+ * Interface to control the chip select signal
+ */
+static void davinci_spi_chipselect(struct spi_device *spi, int value)
+{
+	struct davinci_spi *dspi;
+	struct davinci_spi_platform_data *pdata;
+	struct davinci_spi_config *spicfg = spi->controller_data;
+	u8 chip_sel = spi->chip_select;
+	u16 spidat1 = CS_DEFAULT;
+
+	dspi = spi_master_get_devdata(spi->master);
+	pdata = &dspi->pdata;
+
+	/* program delay transfers if tx_delay is non zero */
+	if (spicfg && spicfg->wdelay)
+		spidat1 |= SPIDAT1_WDEL;
+
+	/*
+	 * Board specific chip select logic decides the polarity and cs
+	 * line for the controller
+	 */
+	if (spi->cs_gpio >= 0) {
+		if (value == BITBANG_CS_ACTIVE)
+			gpio_set_value(spi->cs_gpio, spi->mode & SPI_CS_HIGH);
+		else
+			gpio_set_value(spi->cs_gpio,
+				!(spi->mode & SPI_CS_HIGH));
+	} else {
+		if (value == BITBANG_CS_ACTIVE) {
+			spidat1 |= SPIDAT1_CSHOLD_MASK;
+			spidat1 &= ~(0x1 << chip_sel);
+		}
+	}
+
+	iowrite16(spidat1, dspi->base + SPIDAT1 + 2);
+}
+
+/**
+ * davinci_spi_get_prescale - Calculates the correct prescale value
+ * @maxspeed_hz: the maximum rate the SPI clock can run at
+ *
+ * This function calculates the prescale value that generates a clock rate
+ * less than or equal to the specified maximum.
+ *
+ * Returns: calculated prescale value for easy programming into SPI registers
+ * or negative error number if valid prescalar cannot be updated.
+ */
+static inline int davinci_spi_get_prescale(struct davinci_spi *dspi,
+							u32 max_speed_hz)
+{
+	int ret;
+
+	/* Subtract 1 to match what will be programmed into SPI register. */
+	ret = DIV_ROUND_UP(clk_get_rate(dspi->clk), max_speed_hz) - 1;
+
+	if (ret < dspi->prescaler_limit || ret > 255)
+		return -EINVAL;
+
+	return ret;
+}
+
+/**
+ * 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 *dspi;
+	struct davinci_spi_config *spicfg;
+	u8 bits_per_word = 0;
+	u32 hz = 0, spifmt = 0;
+	int prescale;
+
+	dspi = spi_master_get_devdata(spi->master);
+	spicfg = spi->controller_data;
+	if (!spicfg)
+		spicfg = &davinci_spi_default_cfg;
+
+	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) {
+		dspi->get_rx = davinci_spi_rx_buf_u8;
+		dspi->get_tx = davinci_spi_tx_buf_u8;
+		dspi->bytes_per_word[spi->chip_select] = 1;
+	} else {
+		dspi->get_rx = davinci_spi_rx_buf_u16;
+		dspi->get_tx = davinci_spi_tx_buf_u16;
+		dspi->bytes_per_word[spi->chip_select] = 2;
+	}
+
+	if (!hz)
+		hz = spi->max_speed_hz;
+
+	/* Set up SPIFMTn register, unique to this chipselect. */
+
+	prescale = davinci_spi_get_prescale(dspi, hz);
+	if (prescale < 0)
+		return prescale;
+
+	spifmt = (prescale << SPIFMT_PRESCALE_SHIFT) | (bits_per_word & 0x1f);
+
+	if (spi->mode & SPI_LSB_FIRST)
+		spifmt |= SPIFMT_SHIFTDIR_MASK;
+
+	if (spi->mode & SPI_CPOL)
+		spifmt |= SPIFMT_POLARITY_MASK;
+
+	if (!(spi->mode & SPI_CPHA))
+		spifmt |= SPIFMT_PHASE_MASK;
+
+	/*
+	* Assume wdelay is used only on SPI peripherals that has this field
+	* in SPIFMTn register and when it's configured from board file or DT.
+	*/
+	if (spicfg->wdelay)
+		spifmt |= ((spicfg->wdelay << SPIFMT_WDELAY_SHIFT)
+				& SPIFMT_WDELAY_MASK);
+
+	/*
+	 * 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 (dspi->version == SPI_VERSION_2) {
+
+		u32 delay = 0;
+
+		if (spicfg->odd_parity)
+			spifmt |= SPIFMT_ODD_PARITY_MASK;
+
+		if (spicfg->parity_enable)
+			spifmt |= SPIFMT_PARITYENA_MASK;
+
+		if (spicfg->timer_disable) {
+			spifmt |= SPIFMT_DISTIMER_MASK;
+		} else {
+			delay |= (spicfg->c2tdelay << SPIDELAY_C2TDELAY_SHIFT)
+						& SPIDELAY_C2TDELAY_MASK;
+			delay |= (spicfg->t2cdelay << SPIDELAY_T2CDELAY_SHIFT)
+						& SPIDELAY_T2CDELAY_MASK;
+		}
+
+		if (spi->mode & SPI_READY) {
+			spifmt |= SPIFMT_WAITENA_MASK;
+			delay |= (spicfg->t2edelay << SPIDELAY_T2EDELAY_SHIFT)
+						& SPIDELAY_T2EDELAY_MASK;
+			delay |= (spicfg->c2edelay << SPIDELAY_C2EDELAY_SHIFT)
+						& SPIDELAY_C2EDELAY_MASK;
+		}
+
+		iowrite32(delay, dspi->base + SPIDELAY);
+	}
+
+	iowrite32(spifmt, dspi->base + SPIFMT0);
+
+	return 0;
+}
+
+static int davinci_spi_of_setup(struct spi_device *spi)
+{
+	struct davinci_spi_config *spicfg = spi->controller_data;
+	struct device_node *np = spi->dev.of_node;
+	struct davinci_spi *dspi = spi_master_get_devdata(spi->master);
+	u32 prop;
+
+	if (spicfg == NULL && np) {
+		spicfg = kzalloc(sizeof(*spicfg), GFP_KERNEL);
+		if (!spicfg)
+			return -ENOMEM;
+		*spicfg = davinci_spi_default_cfg;
+		/* override with dt configured values */
+		if (!of_property_read_u32(np, "ti,spi-wdelay", &prop))
+			spicfg->wdelay = (u8)prop;
+		spi->controller_data = spicfg;
+
+		if (dspi->dma_rx && dspi->dma_tx)
+			spicfg->io_type = SPI_IO_TYPE_DMA;
+	}
+
+	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 = 0;
+	struct davinci_spi *dspi;
+	struct davinci_spi_platform_data *pdata;
+	struct spi_master *master = spi->master;
+	struct device_node *np = spi->dev.of_node;
+	bool internal_cs = true;
+
+	dspi = spi_master_get_devdata(spi->master);
+	pdata = &dspi->pdata;
+
+	if (!(spi->mode & SPI_NO_CS)) {
+		if (np && (master->cs_gpios != NULL) && (spi->cs_gpio >= 0)) {
+			retval = gpio_direction_output(
+				      spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
+			internal_cs = false;
+		} else if (pdata->chip_sel &&
+			   spi->chip_select < pdata->num_chipselect &&
+			   pdata->chip_sel[spi->chip_select] != SPI_INTERN_CS) {
+			spi->cs_gpio = pdata->chip_sel[spi->chip_select];
+			retval = gpio_direction_output(
+				      spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
+			internal_cs = false;
+		}
+
+		if (retval) {
+			dev_err(&spi->dev, "GPIO %d setup failed (%d)\n",
+				spi->cs_gpio, retval);
+			return retval;
+		}
+
+		if (internal_cs)
+			set_io_bits(dspi->base + SPIPC0, 1 << spi->chip_select);
+	}
+
+	if (spi->mode & SPI_READY)
+		set_io_bits(dspi->base + SPIPC0, SPIPC0_SPIENA_MASK);
+
+	if (spi->mode & SPI_LOOP)
+		set_io_bits(dspi->base + SPIGCR1, SPIGCR1_LOOPBACK_MASK);
+	else
+		clear_io_bits(dspi->base + SPIGCR1, SPIGCR1_LOOPBACK_MASK);
+
+	return davinci_spi_of_setup(spi);
+}
+
+static void davinci_spi_cleanup(struct spi_device *spi)
+{
+	struct davinci_spi_config *spicfg = spi->controller_data;
+
+	spi->controller_data = NULL;
+	if (spi->dev.of_node)
+		kfree(spicfg);
+}
+
+static bool davinci_spi_can_dma(struct spi_master *master,
+				struct spi_device *spi,
+				struct spi_transfer *xfer)
+{
+	struct davinci_spi_config *spicfg = spi->controller_data;
+	bool can_dma = false;
+
+	if (spicfg)
+		can_dma = (spicfg->io_type == SPI_IO_TYPE_DMA) &&
+			(xfer->len >= DMA_MIN_BYTES) &&
+			!is_vmalloc_addr(xfer->rx_buf) &&
+			!is_vmalloc_addr(xfer->tx_buf);
+
+	return can_dma;
+}
+
+static int davinci_spi_check_error(struct davinci_spi *dspi, int int_status)
+{
+	struct device *sdev = dspi->bitbang.master->dev.parent;
+
+	if (int_status & SPIFLG_TIMEOUT_MASK) {
+		dev_err(sdev, "SPI Time-out Error\n");
+		return -ETIMEDOUT;
+	}
+	if (int_status & SPIFLG_DESYNC_MASK) {
+		dev_err(sdev, "SPI Desynchronization Error\n");
+		return -EIO;
+	}
+	if (int_status & SPIFLG_BITERR_MASK) {
+		dev_err(sdev, "SPI Bit error\n");
+		return -EIO;
+	}
+
+	if (dspi->version == SPI_VERSION_2) {
+		if (int_status & SPIFLG_DLEN_ERR_MASK) {
+			dev_err(sdev, "SPI Data Length Error\n");
+			return -EIO;
+		}
+		if (int_status & SPIFLG_PARERR_MASK) {
+			dev_err(sdev, "SPI Parity Error\n");
+			return -EIO;
+		}
+		if (int_status & SPIFLG_OVRRUN_MASK) {
+			dev_err(sdev, "SPI Data Overrun error\n");
+			return -EIO;
+		}
+		if (int_status & SPIFLG_BUF_INIT_ACTIVE_MASK) {
+			dev_err(sdev, "SPI Buffer Init Active\n");
+			return -EBUSY;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * davinci_spi_process_events - check for and handle any SPI controller events
+ * @dspi: the controller data
+ *
+ * This function will check the SPIFLG register and handle any events that are
+ * detected there
+ */
+static int davinci_spi_process_events(struct davinci_spi *dspi)
+{
+	u32 buf, status, errors = 0, spidat1;
+
+	buf = ioread32(dspi->base + SPIBUF);
+
+	if (dspi->rcount > 0 && !(buf & SPIBUF_RXEMPTY_MASK)) {
+		dspi->get_rx(buf & 0xFFFF, dspi);
+		dspi->rcount--;
+	}
+
+	status = ioread32(dspi->base + SPIFLG);
+
+	if (unlikely(status & SPIFLG_ERROR_MASK)) {
+		errors = status & SPIFLG_ERROR_MASK;
+		goto out;
+	}
+
+	if (dspi->wcount > 0 && !(buf & SPIBUF_TXFULL_MASK)) {
+		spidat1 = ioread32(dspi->base + SPIDAT1);
+		dspi->wcount--;
+		spidat1 &= ~0xFFFF;
+		spidat1 |= 0xFFFF & dspi->get_tx(dspi);
+		iowrite32(spidat1, dspi->base + SPIDAT1);
+	}
+
+out:
+	return errors;
+}
+
+static void davinci_spi_dma_rx_callback(void *data)
+{
+	struct davinci_spi *dspi = (struct davinci_spi *)data;
+
+	dspi->rcount = 0;
+
+	if (!dspi->wcount && !dspi->rcount)
+		complete(&dspi->done);
+}
+
+static void davinci_spi_dma_tx_callback(void *data)
+{
+	struct davinci_spi *dspi = (struct davinci_spi *)data;
+
+	dspi->wcount = 0;
+
+	if (!dspi->wcount && !dspi->rcount)
+		complete(&dspi->done);
+}
+
+/**
+ * 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(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct davinci_spi *dspi;
+	int data_type, ret = -ENOMEM;
+	u32 tx_data, spidat1;
+	u32 errors = 0;
+	struct davinci_spi_config *spicfg;
+	struct davinci_spi_platform_data *pdata;
+	unsigned uninitialized_var(rx_buf_count);
+
+	dspi = spi_master_get_devdata(spi->master);
+	pdata = &dspi->pdata;
+	spicfg = (struct davinci_spi_config *)spi->controller_data;
+	if (!spicfg)
+		spicfg = &davinci_spi_default_cfg;
+
+	/* convert len to words based on bits_per_word */
+	data_type = dspi->bytes_per_word[spi->chip_select];
+
+	dspi->tx = t->tx_buf;
+	dspi->rx = t->rx_buf;
+	dspi->wcount = t->len / data_type;
+	dspi->rcount = dspi->wcount;
+
+	spidat1 = ioread32(dspi->base + SPIDAT1);
+
+	clear_io_bits(dspi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK);
+	set_io_bits(dspi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
+
+	reinit_completion(&dspi->done);
+
+	if (!davinci_spi_can_dma(spi->master, spi, t)) {
+		if (spicfg->io_type != SPI_IO_TYPE_POLL)
+			set_io_bits(dspi->base + SPIINT, SPIINT_MASKINT);
+		/* start the transfer */
+		dspi->wcount--;
+		tx_data = dspi->get_tx(dspi);
+		spidat1 &= 0xFFFF0000;
+		spidat1 |= tx_data & 0xFFFF;
+		iowrite32(spidat1, dspi->base + SPIDAT1);
+	} else {
+		struct dma_slave_config dma_rx_conf = {
+			.direction = DMA_DEV_TO_MEM,
+			.src_addr = (unsigned long)dspi->pbase + SPIBUF,
+			.src_addr_width = data_type,
+			.src_maxburst = 1,
+		};
+		struct dma_slave_config dma_tx_conf = {
+			.direction = DMA_MEM_TO_DEV,
+			.dst_addr = (unsigned long)dspi->pbase + SPIDAT1,
+			.dst_addr_width = data_type,
+			.dst_maxburst = 1,
+		};
+		struct dma_async_tx_descriptor *rxdesc;
+		struct dma_async_tx_descriptor *txdesc;
+
+		dmaengine_slave_config(dspi->dma_rx, &dma_rx_conf);
+		dmaengine_slave_config(dspi->dma_tx, &dma_tx_conf);
+
+		rxdesc = dmaengine_prep_slave_sg(dspi->dma_rx,
+				t->rx_sg.sgl, t->rx_sg.nents, DMA_DEV_TO_MEM,
+				DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+		if (!rxdesc)
+			goto err_desc;
+
+		if (!t->tx_buf) {
+			/* To avoid errors when doing rx-only transfers with
+			 * many SG entries (> 20), use the rx buffer as the
+			 * dummy tx buffer so that dma reloads are done at the
+			 * same time for rx and tx.
+			 */
+			t->tx_sg.sgl = t->rx_sg.sgl;
+			t->tx_sg.nents = t->rx_sg.nents;
+		}
+
+		txdesc = dmaengine_prep_slave_sg(dspi->dma_tx,
+				t->tx_sg.sgl, t->tx_sg.nents, DMA_MEM_TO_DEV,
+				DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+		if (!txdesc)
+			goto err_desc;
+
+		rxdesc->callback = davinci_spi_dma_rx_callback;
+		rxdesc->callback_param = (void *)dspi;
+		txdesc->callback = davinci_spi_dma_tx_callback;
+		txdesc->callback_param = (void *)dspi;
+
+		if (pdata->cshold_bug)
+			iowrite16(spidat1 >> 16, dspi->base + SPIDAT1 + 2);
+
+		dmaengine_submit(rxdesc);
+		dmaengine_submit(txdesc);
+
+		dma_async_issue_pending(dspi->dma_rx);
+		dma_async_issue_pending(dspi->dma_tx);
+
+		set_io_bits(dspi->base + SPIINT, SPIINT_DMA_REQ_EN);
+	}
+
+	/* Wait for the transfer to complete */
+	if (spicfg->io_type != SPI_IO_TYPE_POLL) {
+		if (wait_for_completion_timeout(&dspi->done, HZ) == 0)
+			errors = SPIFLG_TIMEOUT_MASK;
+	} else {
+		while (dspi->rcount > 0 || dspi->wcount > 0) {
+			errors = davinci_spi_process_events(dspi);
+			if (errors)
+				break;
+			cpu_relax();
+		}
+	}
+
+	clear_io_bits(dspi->base + SPIINT, SPIINT_MASKALL);
+	if (davinci_spi_can_dma(spi->master, spi, t))
+		clear_io_bits(dspi->base + SPIINT, SPIINT_DMA_REQ_EN);
+
+	clear_io_bits(dspi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
+	set_io_bits(dspi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK);
+
+	/*
+	 * Check for bit error, desync error,parity error,timeout error and
+	 * receive overflow errors
+	 */
+	if (errors) {
+		ret = davinci_spi_check_error(dspi, errors);
+		WARN(!ret, "%s: error reported but no error found!\n",
+							dev_name(&spi->dev));
+		return ret;
+	}
+
+	if (dspi->rcount != 0 || dspi->wcount != 0) {
+		dev_err(&spi->dev, "SPI data transfer error\n");
+		return -EIO;
+	}
+
+	return t->len;
+
+err_desc:
+	return ret;
+}
+
+/**
+ * dummy_thread_fn - dummy thread function
+ * @irq: IRQ number for this SPI Master
+ * @context_data: structure for SPI Master controller davinci_spi
+ *
+ * This is to satisfy the request_threaded_irq() API so that the irq
+ * handler is called in interrupt context.
+ */
+static irqreturn_t dummy_thread_fn(s32 irq, void *data)
+{
+	return IRQ_HANDLED;
+}
+
+/**
+ * davinci_spi_irq - Interrupt handler for SPI Master Controller
+ * @irq: IRQ number for this SPI Master
+ * @context_data: structure for SPI Master controller davinci_spi
+ *
+ * ISR will determine that interrupt arrives either for READ or WRITE command.
+ * According to command it will do the appropriate action. It will check
+ * transfer length and if it is not zero then dispatch transfer command again.
+ * If transfer length is zero then it will indicate the COMPLETION so that
+ * davinci_spi_bufs function can go ahead.
+ */
+static irqreturn_t davinci_spi_irq(s32 irq, void *data)
+{
+	struct davinci_spi *dspi = data;
+	int status;
+
+	status = davinci_spi_process_events(dspi);
+	if (unlikely(status != 0))
+		clear_io_bits(dspi->base + SPIINT, SPIINT_MASKINT);
+
+	if ((!dspi->rcount && !dspi->wcount) || status)
+		complete(&dspi->done);
+
+	return IRQ_HANDLED;
+}
+
+static int davinci_spi_request_dma(struct davinci_spi *dspi)
+{
+	struct device *sdev = dspi->bitbang.master->dev.parent;
+
+	dspi->dma_rx = dma_request_chan(sdev, "rx");
+	if (IS_ERR(dspi->dma_rx))
+		return PTR_ERR(dspi->dma_rx);
+
+	dspi->dma_tx = dma_request_chan(sdev, "tx");
+	if (IS_ERR(dspi->dma_tx)) {
+		dma_release_channel(dspi->dma_rx);
+		return PTR_ERR(dspi->dma_tx);
+	}
+
+	return 0;
+}
+
+#if defined(CONFIG_OF)
+
+/* OF SPI data structure */
+struct davinci_spi_of_data {
+	u8	version;
+	u8	prescaler_limit;
+};
+
+static const struct davinci_spi_of_data dm6441_spi_data = {
+	.version = SPI_VERSION_1,
+	.prescaler_limit = 2,
+};
+
+static const struct davinci_spi_of_data da830_spi_data = {
+	.version = SPI_VERSION_2,
+	.prescaler_limit = 2,
+};
+
+static const struct davinci_spi_of_data keystone_spi_data = {
+	.version = SPI_VERSION_1,
+	.prescaler_limit = 0,
+};
+
+static const struct of_device_id davinci_spi_of_match[] = {
+	{
+		.compatible = "ti,dm6441-spi",
+		.data = &dm6441_spi_data,
+	},
+	{
+		.compatible = "ti,da830-spi",
+		.data = &da830_spi_data,
+	},
+	{
+		.compatible = "ti,keystone-spi",
+		.data = &keystone_spi_data,
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, davinci_spi_of_match);
+
+/**
+ * spi_davinci_get_pdata - Get platform data from DTS binding
+ * @pdev: ptr to platform data
+ * @dspi: ptr to driver data
+ *
+ * Parses and populates pdata in dspi from device tree bindings.
+ *
+ * NOTE: Not all platform data params are supported currently.
+ */
+static int spi_davinci_get_pdata(struct platform_device *pdev,
+			struct davinci_spi *dspi)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct davinci_spi_of_data *spi_data;
+	struct davinci_spi_platform_data *pdata;
+	unsigned int num_cs, intr_line = 0;
+	const struct of_device_id *match;
+
+	pdata = &dspi->pdata;
+
+	match = of_match_device(davinci_spi_of_match, &pdev->dev);
+	if (!match)
+		return -ENODEV;
+
+	spi_data = (struct davinci_spi_of_data *)match->data;
+
+	pdata->version = spi_data->version;
+	pdata->prescaler_limit = spi_data->prescaler_limit;
+	/*
+	 * default num_cs is 1 and all chipsel are internal to the chip
+	 * indicated by chip_sel being NULL or cs_gpios being NULL or
+	 * set to -ENOENT. num-cs includes internal as well as gpios.
+	 * indicated by chip_sel being NULL. GPIO based CS is not
+	 * supported yet in DT bindings.
+	 */
+	num_cs = 1;
+	of_property_read_u32(node, "num-cs", &num_cs);
+	pdata->num_chipselect = num_cs;
+	of_property_read_u32(node, "ti,davinci-spi-intr-line", &intr_line);
+	pdata->intr_line = intr_line;
+	return 0;
+}
+#else
+static int spi_davinci_get_pdata(struct platform_device *pdev,
+			struct davinci_spi *dspi)
+{
+	return -ENODEV;
+}
+#endif
+
+/**
+ * davinci_spi_probe - probe function for SPI Master Controller
+ * @pdev: platform_device structure which contains plateform specific data
+ *
+ * According to Linux Device Model this function will be invoked by Linux
+ * with platform_device struct which contains the device specific info.
+ * This function will map the SPI controller's memory, register IRQ,
+ * Reset SPI controller and setting its registers to default value.
+ * It will invoke spi_bitbang_start to create work queue so that client driver
+ * can register transfer method to work queue.
+ */
+static int davinci_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct davinci_spi *dspi;
+	struct davinci_spi_platform_data *pdata;
+	struct resource *r;
+	int ret = 0;
+	u32 spipc0;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct davinci_spi));
+	if (master == NULL) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	platform_set_drvdata(pdev, master);
+
+	dspi = spi_master_get_devdata(master);
+
+	if (dev_get_platdata(&pdev->dev)) {
+		pdata = dev_get_platdata(&pdev->dev);
+		dspi->pdata = *pdata;
+	} else {
+		/* update dspi pdata with that from the DT */
+		ret = spi_davinci_get_pdata(pdev, dspi);
+		if (ret < 0)
+			goto free_master;
+	}
+
+	/* pdata in dspi is now updated and point pdata to that */
+	pdata = &dspi->pdata;
+
+	dspi->bytes_per_word = devm_kcalloc(&pdev->dev,
+					    pdata->num_chipselect,
+					    sizeof(*dspi->bytes_per_word),
+					    GFP_KERNEL);
+	if (dspi->bytes_per_word == NULL) {
+		ret = -ENOMEM;
+		goto free_master;
+	}
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		ret = -ENOENT;
+		goto free_master;
+	}
+
+	dspi->pbase = r->start;
+
+	dspi->base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(dspi->base)) {
+		ret = PTR_ERR(dspi->base);
+		goto free_master;
+	}
+
+	init_completion(&dspi->done);
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret == 0)
+		ret = -EINVAL;
+	if (ret < 0)
+		goto free_master;
+	dspi->irq = ret;
+
+	ret = devm_request_threaded_irq(&pdev->dev, dspi->irq, davinci_spi_irq,
+				dummy_thread_fn, 0, dev_name(&pdev->dev), dspi);
+	if (ret)
+		goto free_master;
+
+	dspi->bitbang.master = master;
+
+	dspi->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(dspi->clk)) {
+		ret = -ENODEV;
+		goto free_master;
+	}
+	ret = clk_prepare_enable(dspi->clk);
+	if (ret)
+		goto free_master;
+
+	master->dev.of_node = pdev->dev.of_node;
+	master->bus_num = pdev->id;
+	master->num_chipselect = pdata->num_chipselect;
+	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(2, 16);
+	master->flags = SPI_MASTER_MUST_RX;
+	master->setup = davinci_spi_setup;
+	master->cleanup = davinci_spi_cleanup;
+	master->can_dma = davinci_spi_can_dma;
+
+	dspi->bitbang.chipselect = davinci_spi_chipselect;
+	dspi->bitbang.setup_transfer = davinci_spi_setup_transfer;
+	dspi->prescaler_limit = pdata->prescaler_limit;
+	dspi->version = pdata->version;
+
+	dspi->bitbang.flags = SPI_NO_CS | SPI_LSB_FIRST | SPI_LOOP;
+	if (dspi->version == SPI_VERSION_2)
+		dspi->bitbang.flags |= SPI_READY;
+
+	if (pdev->dev.of_node) {
+		int i;
+
+		for (i = 0; i < pdata->num_chipselect; i++) {
+			int cs_gpio = of_get_named_gpio(pdev->dev.of_node,
+							"cs-gpios", i);
+
+			if (cs_gpio == -EPROBE_DEFER) {
+				ret = cs_gpio;
+				goto free_clk;
+			}
+
+			if (gpio_is_valid(cs_gpio)) {
+				ret = devm_gpio_request(&pdev->dev, cs_gpio,
+							dev_name(&pdev->dev));
+				if (ret)
+					goto free_clk;
+			}
+		}
+	}
+
+	dspi->bitbang.txrx_bufs = davinci_spi_bufs;
+
+	ret = davinci_spi_request_dma(dspi);
+	if (ret == -EPROBE_DEFER) {
+		goto free_clk;
+	} else if (ret) {
+		dev_info(&pdev->dev, "DMA is not supported (%d)\n", ret);
+		dspi->dma_rx = NULL;
+		dspi->dma_tx = NULL;
+	}
+
+	dspi->get_rx = davinci_spi_rx_buf_u8;
+	dspi->get_tx = davinci_spi_tx_buf_u8;
+
+	/* Reset In/OUT SPI module */
+	iowrite32(0, dspi->base + SPIGCR0);
+	udelay(100);
+	iowrite32(1, dspi->base + SPIGCR0);
+
+	/* Set up SPIPC0.  CS and ENA init is done in davinci_spi_setup */
+	spipc0 = SPIPC0_DIFUN_MASK | SPIPC0_DOFUN_MASK | SPIPC0_CLKFUN_MASK;
+	iowrite32(spipc0, dspi->base + SPIPC0);
+
+	if (pdata->intr_line)
+		iowrite32(SPI_INTLVL_1, dspi->base + SPILVL);
+	else
+		iowrite32(SPI_INTLVL_0, dspi->base + SPILVL);
+
+	iowrite32(CS_DEFAULT, dspi->base + SPIDEF);
+
+	/* master mode default */
+	set_io_bits(dspi->base + SPIGCR1, SPIGCR1_CLKMOD_MASK);
+	set_io_bits(dspi->base + SPIGCR1, SPIGCR1_MASTER_MASK);
+	set_io_bits(dspi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK);
+
+	ret = spi_bitbang_start(&dspi->bitbang);
+	if (ret)
+		goto free_dma;
+
+	dev_info(&pdev->dev, "Controller at 0x%p\n", dspi->base);
+
+	return ret;
+
+free_dma:
+	if (dspi->dma_rx) {
+		dma_release_channel(dspi->dma_rx);
+		dma_release_channel(dspi->dma_tx);
+	}
+free_clk:
+	clk_disable_unprepare(dspi->clk);
+free_master:
+	spi_master_put(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 davinci_spi_remove(struct platform_device *pdev)
+{
+	struct davinci_spi *dspi;
+	struct spi_master *master;
+
+	master = platform_get_drvdata(pdev);
+	dspi = spi_master_get_devdata(master);
+
+	spi_bitbang_stop(&dspi->bitbang);
+
+	clk_disable_unprepare(dspi->clk);
+
+	if (dspi->dma_rx) {
+		dma_release_channel(dspi->dma_rx);
+		dma_release_channel(dspi->dma_tx);
+	}
+
+	spi_master_put(master);
+	return 0;
+}
+
+static struct platform_driver davinci_spi_driver = {
+	.driver = {
+		.name = "spi_davinci",
+		.of_match_table = of_match_ptr(davinci_spi_of_match),
+	},
+	.probe = davinci_spi_probe,
+	.remove = davinci_spi_remove,
+};
+module_platform_driver(davinci_spi_driver);
+
+MODULE_DESCRIPTION("TI DaVinci SPI Master Controller Driver");
+MODULE_LICENSE("GPL");