drivers/spi/tegra114_spi.c - github/trini/u-boot - Gitiles

 /*
  * NVIDIA Tegra SPI controller (T114 and later)
  *
  * Copyright (c) 2010-2013 NVIDIA Corporation
  *
  * See file CREDITS for list of people who contributed to this
  * project.
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
  * may be copied, distributed, and modified under those terms.
  *
  * 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 <common.h>
 #include <dm.h>
 #include <asm/io.h>
 #include <asm/arch/clock.h>
 #include <asm/arch-tegra/clk_rst.h>
 #include <spi.h>
 #include <fdtdec.h>
 #include "tegra_spi.h"

 DECLARE_GLOBAL_DATA_PTR;

 /* COMMAND1 */
 #define SPI_CMD1_GO			BIT(31)
 #define SPI_CMD1_M_S			BIT(30)
 #define SPI_CMD1_MODE_MASK		GENMASK(1, 0)
 #define SPI_CMD1_MODE_SHIFT		28
 #define SPI_CMD1_CS_SEL_MASK		GENMASK(1, 0)
 #define SPI_CMD1_CS_SEL_SHIFT		26
 #define SPI_CMD1_CS_POL_INACTIVE3	BIT(25)
 #define SPI_CMD1_CS_POL_INACTIVE2	BIT(24)
 #define SPI_CMD1_CS_POL_INACTIVE1	BIT(23)
 #define SPI_CMD1_CS_POL_INACTIVE0	BIT(22)
 #define SPI_CMD1_CS_SW_HW		BIT(21)
 #define SPI_CMD1_CS_SW_VAL		BIT(20)
 #define SPI_CMD1_IDLE_SDA_MASK		GENMASK(1, 0)
 #define SPI_CMD1_IDLE_SDA_SHIFT		18
 #define SPI_CMD1_BIDIR			BIT(17)
 #define SPI_CMD1_LSBI_FE		BIT(16)
 #define SPI_CMD1_LSBY_FE		BIT(15)
 #define SPI_CMD1_BOTH_EN_BIT		BIT(14)
 #define SPI_CMD1_BOTH_EN_BYTE		BIT(13)
 #define SPI_CMD1_RX_EN			BIT(12)
 #define SPI_CMD1_TX_EN			BIT(11)
 #define SPI_CMD1_PACKED			BIT(5)
 #define SPI_CMD1_BIT_LEN_MASK		GENMASK(4, 0)
 #define SPI_CMD1_BIT_LEN_SHIFT		0

 /* COMMAND2 */
 #define SPI_CMD2_TX_CLK_TAP_DELAY	BIT(6)
 #define SPI_CMD2_TX_CLK_TAP_DELAY_MASK	GENMASK(11, 6)
 #define SPI_CMD2_RX_CLK_TAP_DELAY	BIT(0)
 #define SPI_CMD2_RX_CLK_TAP_DELAY_MASK	GENMASK(5, 0)

 /* TRANSFER STATUS */
 #define SPI_XFER_STS_RDY		BIT(30)

 /* FIFO STATUS */
 #define SPI_FIFO_STS_CS_INACTIVE	BIT(31)
 #define SPI_FIFO_STS_FRAME_END		BIT(30)
 #define SPI_FIFO_STS_RX_FIFO_FLUSH	BIT(15)
 #define SPI_FIFO_STS_TX_FIFO_FLUSH	BIT(14)
 #define SPI_FIFO_STS_ERR		BIT(8)
 #define SPI_FIFO_STS_TX_FIFO_OVF	BIT(7)
 #define SPI_FIFO_STS_TX_FIFO_UNR	BIT(6)
 #define SPI_FIFO_STS_RX_FIFO_OVF	BIT(5)
 #define SPI_FIFO_STS_RX_FIFO_UNR	BIT(4)
 #define SPI_FIFO_STS_TX_FIFO_FULL	BIT(3)
 #define SPI_FIFO_STS_TX_FIFO_EMPTY	BIT(2)
 #define SPI_FIFO_STS_RX_FIFO_FULL	BIT(1)
 #define SPI_FIFO_STS_RX_FIFO_EMPTY	BIT(0)

 #define SPI_TIMEOUT		1000
 #define TEGRA_SPI_MAX_FREQ	52000000

 struct spi_regs {
 	u32 command1;	/* 000:SPI_COMMAND1 register */
 	u32 command2;	/* 004:SPI_COMMAND2 register */
 	u32 timing1;	/* 008:SPI_CS_TIM1 register */
 	u32 timing2;	/* 00c:SPI_CS_TIM2 register */
 	u32 xfer_status;/* 010:SPI_TRANS_STATUS register */
 	u32 fifo_status;/* 014:SPI_FIFO_STATUS register */
 	u32 tx_data;	/* 018:SPI_TX_DATA register */
 	u32 rx_data;	/* 01c:SPI_RX_DATA register */
 	u32 dma_ctl;	/* 020:SPI_DMA_CTL register */
 	u32 dma_blk;	/* 024:SPI_DMA_BLK register */
 	u32 rsvd[56];	/* 028-107 reserved */
 	u32 tx_fifo;	/* 108:SPI_FIFO1 register */
 	u32 rsvd2[31];	/* 10c-187 reserved */
 	u32 rx_fifo;	/* 188:SPI_FIFO2 register */
 	u32 spare_ctl;	/* 18c:SPI_SPARE_CTRL register */
 };

 struct tegra114_spi_priv {
 	struct spi_regs *regs;
 	unsigned int freq;
 	unsigned int mode;
 	int periph_id;
 	int valid;
 	int last_transaction_us;
 };

 static int tegra114_spi_ofdata_to_platdata(struct udevice *bus)
 {
 	struct tegra_spi_platdata *plat = bus->platdata;
 	const void *blob = gd->fdt_blob;
 	int node = bus->of_offset;

 	plat->base = dev_get_addr(bus);
 	plat->periph_id = clock_decode_periph_id(blob, node);

 	if (plat->periph_id == PERIPH_ID_NONE) {
 		debug("%s: could not decode periph id %d\n", __func__,
 		      plat->periph_id);
 		return -FDT_ERR_NOTFOUND;
 	}

 	/* Use 500KHz as a suitable default */
 	plat->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
 					500000);
 	plat->deactivate_delay_us = fdtdec_get_int(blob, node,
 					"spi-deactivate-delay", 0);
 	debug("%s: base=%#08lx, periph_id=%d, max-frequency=%d, deactivate_delay=%d\n",
 	      __func__, plat->base, plat->periph_id, plat->frequency,
 	      plat->deactivate_delay_us);

 	return 0;
 }

 static int tegra114_spi_probe(struct udevice *bus)
 {
 	struct tegra_spi_platdata *plat = dev_get_platdata(bus);
 	struct tegra114_spi_priv *priv = dev_get_priv(bus);
 	struct spi_regs *regs;
 	ulong rate;

 	priv->regs = (struct spi_regs *)plat->base;
 	regs = priv->regs;

 	priv->last_transaction_us = timer_get_us();
 	priv->freq = plat->frequency;
 	priv->periph_id = plat->periph_id;

 	/*
 	 * Change SPI clock to correct frequency, PLLP_OUT0 source, falling
 	 * back to the oscillator if that is too fast.
 	 */
 	rate = clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH,
 				      priv->freq);
 	if (rate > priv->freq + 100000) {
 		rate = clock_start_periph_pll(priv->periph_id, CLOCK_ID_OSC,
 					      priv->freq);
 		if (rate != priv->freq) {
 			printf("Warning: SPI '%s' requested clock %u, actual clock %lu\n",
 			       bus->name, priv->freq, rate);
 		}
 	}

 	/* Clear stale status here */
 	setbits_le32(&regs->fifo_status,
 		     SPI_FIFO_STS_ERR		|
 		     SPI_FIFO_STS_TX_FIFO_OVF	|
 		     SPI_FIFO_STS_TX_FIFO_UNR	|
 		     SPI_FIFO_STS_RX_FIFO_OVF	|
 		     SPI_FIFO_STS_RX_FIFO_UNR	|
 		     SPI_FIFO_STS_TX_FIFO_FULL	|
 		     SPI_FIFO_STS_TX_FIFO_EMPTY	|
 		     SPI_FIFO_STS_RX_FIFO_FULL	|
 		     SPI_FIFO_STS_RX_FIFO_EMPTY);
 	debug("%s: FIFO STATUS = %08x\n", __func__, readl(&regs->fifo_status));

 	setbits_le32(&priv->regs->command1, SPI_CMD1_M_S | SPI_CMD1_CS_SW_HW |
 		     (priv->mode << SPI_CMD1_MODE_SHIFT) | SPI_CMD1_CS_SW_VAL);
 	debug("%s: COMMAND1 = %08x\n", __func__, readl(&regs->command1));

 	return 0;
 }

 /**
  * Activate the CS by driving it LOW
  *
  * @param slave	Pointer to spi_slave to which controller has to
  *		communicate with
  */
 static void spi_cs_activate(struct udevice *dev)
 {
 	struct udevice *bus = dev->parent;
 	struct tegra_spi_platdata *pdata = dev_get_platdata(bus);
 	struct tegra114_spi_priv *priv = dev_get_priv(bus);

 	/* If it's too soon to do another transaction, wait */
 	if (pdata->deactivate_delay_us &&
 	    priv->last_transaction_us) {
 		ulong delay_us;		/* The delay completed so far */
 		delay_us = timer_get_us() - priv->last_transaction_us;
 		if (delay_us < pdata->deactivate_delay_us)
 			udelay(pdata->deactivate_delay_us - delay_us);
 	}

 	clrbits_le32(&priv->regs->command1, SPI_CMD1_CS_SW_VAL);
 }

 /**
  * Deactivate the CS by driving it HIGH
  *
  * @param slave	Pointer to spi_slave to which controller has to
  *		communicate with
  */
 static void spi_cs_deactivate(struct udevice *dev)
 {
 	struct udevice *bus = dev->parent;
 	struct tegra_spi_platdata *pdata = dev_get_platdata(bus);
 	struct tegra114_spi_priv *priv = dev_get_priv(bus);

 	setbits_le32(&priv->regs->command1, SPI_CMD1_CS_SW_VAL);

 	/* Remember time of this transaction so we can honour the bus delay */
 	if (pdata->deactivate_delay_us)
 		priv->last_transaction_us = timer_get_us();

 	debug("Deactivate CS, bus '%s'\n", bus->name);
 }

 static int tegra114_spi_xfer(struct udevice *dev, unsigned int bitlen,
 			     const void *data_out, void *data_in,
 			     unsigned long flags)
 {
 	struct udevice *bus = dev->parent;
 	struct tegra114_spi_priv *priv = dev_get_priv(bus);
 	struct spi_regs *regs = priv->regs;
 	u32 reg, tmpdout, tmpdin = 0;
 	const u8 *dout = data_out;
 	u8 *din = data_in;
 	int num_bytes;
 	int ret;

 	debug("%s: slave %u:%u dout %p din %p bitlen %u\n",
 	      __func__, bus->seq, spi_chip_select(dev), dout, din, bitlen);
 	if (bitlen % 8)
 		return -1;
 	num_bytes = bitlen / 8;

 	ret = 0;

 	if (flags & SPI_XFER_BEGIN)
 		spi_cs_activate(dev);

 	/* clear all error status bits */
 	reg = readl(&regs->fifo_status);
 	writel(reg, &regs->fifo_status);

 	clrsetbits_le32(&regs->command1, SPI_CMD1_CS_SW_VAL,
 			SPI_CMD1_RX_EN | SPI_CMD1_TX_EN | SPI_CMD1_LSBY_FE |
 			(spi_chip_select(dev) << SPI_CMD1_CS_SEL_SHIFT));

 	/* set xfer size to 1 block (32 bits) */
 	writel(0, &regs->dma_blk);

 	/* handle data in 32-bit chunks */
 	while (num_bytes > 0) {
 		int bytes;
 		int tm, i;

 		tmpdout = 0;
 		bytes = (num_bytes > 4) ?  4 : num_bytes;

 		if (dout != NULL) {
 			for (i = 0; i < bytes; ++i)
 				tmpdout = (tmpdout << 8) | dout[i];
 			dout += bytes;
 		}

 		num_bytes -= bytes;

 		/* clear ready bit */
 		setbits_le32(&regs->xfer_status, SPI_XFER_STS_RDY);

 		clrsetbits_le32(&regs->command1,
 				SPI_CMD1_BIT_LEN_MASK << SPI_CMD1_BIT_LEN_SHIFT,
 				(bytes * 8 - 1) << SPI_CMD1_BIT_LEN_SHIFT);
 		writel(tmpdout, &regs->tx_fifo);
 		setbits_le32(&regs->command1, SPI_CMD1_GO);

 		/*
 		 * Wait for SPI transmit FIFO to empty, or to time out.
 		 * The RX FIFO status will be read and cleared last
 		 */
 		for (tm = 0; tm < SPI_TIMEOUT; ++tm) {
 			u32 fifo_status, xfer_status;

 			xfer_status = readl(&regs->xfer_status);
 			if (!(xfer_status & SPI_XFER_STS_RDY))
 				continue;

 			fifo_status = readl(&regs->fifo_status);
 			if (fifo_status & SPI_FIFO_STS_ERR) {
 				debug("%s: got a fifo error: ", __func__);
 				if (fifo_status & SPI_FIFO_STS_TX_FIFO_OVF)
 					debug("tx FIFO overflow ");
 				if (fifo_status & SPI_FIFO_STS_TX_FIFO_UNR)
 					debug("tx FIFO underrun ");
 				if (fifo_status & SPI_FIFO_STS_RX_FIFO_OVF)
 					debug("rx FIFO overflow ");
 				if (fifo_status & SPI_FIFO_STS_RX_FIFO_UNR)
 					debug("rx FIFO underrun ");
 				if (fifo_status & SPI_FIFO_STS_TX_FIFO_FULL)
 					debug("tx FIFO full ");
 				if (fifo_status & SPI_FIFO_STS_TX_FIFO_EMPTY)
 					debug("tx FIFO empty ");
 				if (fifo_status & SPI_FIFO_STS_RX_FIFO_FULL)
 					debug("rx FIFO full ");
 				if (fifo_status & SPI_FIFO_STS_RX_FIFO_EMPTY)
 					debug("rx FIFO empty ");
 				debug("\n");
 				break;
 			}

 			if (!(fifo_status & SPI_FIFO_STS_RX_FIFO_EMPTY)) {
 				tmpdin = readl(&regs->rx_fifo);

 				/* swap bytes read in */
 				if (din != NULL) {
 					for (i = bytes - 1; i >= 0; --i) {
 						din[i] = tmpdin & 0xff;
 						tmpdin >>= 8;
 					}
 					din += bytes;
 				}

 				/* We can exit when we've had both RX and TX */
 				break;
 			}
 		}

 		if (tm >= SPI_TIMEOUT)
 			ret = tm;

 		/* clear ACK RDY, etc. bits */
 		writel(readl(&regs->fifo_status), &regs->fifo_status);
 	}

 	if (flags & SPI_XFER_END)
 		spi_cs_deactivate(dev);

 	debug("%s: transfer ended. Value=%08x, fifo_status = %08x\n",
 	      __func__, tmpdin, readl(&regs->fifo_status));

 	if (ret) {
 		printf("%s: timeout during SPI transfer, tm %d\n",
 		       __func__, ret);
 		return -1;
 	}

 	return ret;
 }

 static int tegra114_spi_set_speed(struct udevice *bus, uint speed)
 {
 	struct tegra_spi_platdata *plat = bus->platdata;
 	struct tegra114_spi_priv *priv = dev_get_priv(bus);

 	if (speed > plat->frequency)
 		speed = plat->frequency;
 	priv->freq = speed;
 	debug("%s: regs=%p, speed=%d\n", __func__, priv->regs, priv->freq);

 	return 0;
 }

 static int tegra114_spi_set_mode(struct udevice *bus, uint mode)
 {
 	struct tegra114_spi_priv *priv = dev_get_priv(bus);

 	priv->mode = mode;
 	debug("%s: regs=%p, mode=%d\n", __func__, priv->regs, priv->mode);

 	return 0;
 }

 static const struct dm_spi_ops tegra114_spi_ops = {
 	.xfer		= tegra114_spi_xfer,
 	.set_speed	= tegra114_spi_set_speed,
 	.set_mode	= tegra114_spi_set_mode,
 	/*
 	 * cs_info is not needed, since we require all chip selects to be
 	 * in the device tree explicitly
 	 */
 };

 static const struct udevice_id tegra114_spi_ids[] = {
 	{ .compatible = "nvidia,tegra114-spi" },
 	{ }
 };

 U_BOOT_DRIVER(tegra114_spi) = {
 	.name	= "tegra114_spi",
 	.id	= UCLASS_SPI,
 	.of_match = tegra114_spi_ids,
 	.ops	= &tegra114_spi_ops,
 	.ofdata_to_platdata = tegra114_spi_ofdata_to_platdata,
 	.platdata_auto_alloc_size = sizeof(struct tegra_spi_platdata),
 	.priv_auto_alloc_size = sizeof(struct tegra114_spi_priv),
 	.probe	= tegra114_spi_probe,
 };
	/*
	* NVIDIA Tegra SPI controller (T114 and later)
	*
	* Copyright (c) 2010-2013 NVIDIA Corporation
	*
	* See file CREDITS for list of people who contributed to this
	* project.
	*
	* This software is licensed under the terms of the GNU General Public
	* License version 2, as published by the Free Software Foundation, and
	* may be copied, distributed, and modified under those terms.
	*
	* 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 <common.h>
	#include <dm.h>
	#include <asm/io.h>
	#include <asm/arch/clock.h>
	#include <asm/arch-tegra/clk_rst.h>
	#include <spi.h>
	#include <fdtdec.h>
	#include "tegra_spi.h"

	DECLARE_GLOBAL_DATA_PTR;

	/* COMMAND1 */
	#define SPI_CMD1_GO BIT(31)
	#define SPI_CMD1_M_S BIT(30)
	#define SPI_CMD1_MODE_MASK GENMASK(1, 0)
	#define SPI_CMD1_MODE_SHIFT 28
	#define SPI_CMD1_CS_SEL_MASK GENMASK(1, 0)
	#define SPI_CMD1_CS_SEL_SHIFT 26
	#define SPI_CMD1_CS_POL_INACTIVE3 BIT(25)
	#define SPI_CMD1_CS_POL_INACTIVE2 BIT(24)
	#define SPI_CMD1_CS_POL_INACTIVE1 BIT(23)
	#define SPI_CMD1_CS_POL_INACTIVE0 BIT(22)
	#define SPI_CMD1_CS_SW_HW BIT(21)
	#define SPI_CMD1_CS_SW_VAL BIT(20)
	#define SPI_CMD1_IDLE_SDA_MASK GENMASK(1, 0)
	#define SPI_CMD1_IDLE_SDA_SHIFT 18
	#define SPI_CMD1_BIDIR BIT(17)
	#define SPI_CMD1_LSBI_FE BIT(16)
	#define SPI_CMD1_LSBY_FE BIT(15)
	#define SPI_CMD1_BOTH_EN_BIT BIT(14)
	#define SPI_CMD1_BOTH_EN_BYTE BIT(13)
	#define SPI_CMD1_RX_EN BIT(12)
	#define SPI_CMD1_TX_EN BIT(11)
	#define SPI_CMD1_PACKED BIT(5)
	#define SPI_CMD1_BIT_LEN_MASK GENMASK(4, 0)
	#define SPI_CMD1_BIT_LEN_SHIFT 0

	/* COMMAND2 */
	#define SPI_CMD2_TX_CLK_TAP_DELAY BIT(6)
	#define SPI_CMD2_TX_CLK_TAP_DELAY_MASK GENMASK(11, 6)
	#define SPI_CMD2_RX_CLK_TAP_DELAY BIT(0)
	#define SPI_CMD2_RX_CLK_TAP_DELAY_MASK GENMASK(5, 0)

	/* TRANSFER STATUS */
	#define SPI_XFER_STS_RDY BIT(30)

	/* FIFO STATUS */
	#define SPI_FIFO_STS_CS_INACTIVE BIT(31)
	#define SPI_FIFO_STS_FRAME_END BIT(30)
	#define SPI_FIFO_STS_RX_FIFO_FLUSH BIT(15)
	#define SPI_FIFO_STS_TX_FIFO_FLUSH BIT(14)
	#define SPI_FIFO_STS_ERR BIT(8)
	#define SPI_FIFO_STS_TX_FIFO_OVF BIT(7)
	#define SPI_FIFO_STS_TX_FIFO_UNR BIT(6)
	#define SPI_FIFO_STS_RX_FIFO_OVF BIT(5)
	#define SPI_FIFO_STS_RX_FIFO_UNR BIT(4)
	#define SPI_FIFO_STS_TX_FIFO_FULL BIT(3)
	#define SPI_FIFO_STS_TX_FIFO_EMPTY BIT(2)
	#define SPI_FIFO_STS_RX_FIFO_FULL BIT(1)
	#define SPI_FIFO_STS_RX_FIFO_EMPTY BIT(0)

	#define SPI_TIMEOUT 1000
	#define TEGRA_SPI_MAX_FREQ 52000000

	struct spi_regs {
	u32 command1; /* 000:SPI_COMMAND1 register */
	u32 command2; /* 004:SPI_COMMAND2 register */
	u32 timing1; /* 008:SPI_CS_TIM1 register */
	u32 timing2; /* 00c:SPI_CS_TIM2 register */
	u32 xfer_status;/* 010:SPI_TRANS_STATUS register */
	u32 fifo_status;/* 014:SPI_FIFO_STATUS register */
	u32 tx_data; /* 018:SPI_TX_DATA register */
	u32 rx_data; /* 01c:SPI_RX_DATA register */
	u32 dma_ctl; /* 020:SPI_DMA_CTL register */
	u32 dma_blk; /* 024:SPI_DMA_BLK register */
	u32 rsvd[56]; /* 028-107 reserved */
	u32 tx_fifo; /* 108:SPI_FIFO1 register */
	u32 rsvd2[31]; /* 10c-187 reserved */
	u32 rx_fifo; /* 188:SPI_FIFO2 register */
	u32 spare_ctl; /* 18c:SPI_SPARE_CTRL register */
	};

	struct tegra114_spi_priv {
	struct spi_regs *regs;
	unsigned int freq;
	unsigned int mode;
	int periph_id;
	int valid;
	int last_transaction_us;
	};

	static int tegra114_spi_ofdata_to_platdata(struct udevice *bus)
	{
	struct tegra_spi_platdata *plat = bus->platdata;
	const void *blob = gd->fdt_blob;
	int node = bus->of_offset;

	plat->base = dev_get_addr(bus);
	plat->periph_id = clock_decode_periph_id(blob, node);

	if (plat->periph_id == PERIPH_ID_NONE) {
	debug("%s: could not decode periph id %d\n", __func__,
	plat->periph_id);
	return -FDT_ERR_NOTFOUND;
	}

	/* Use 500KHz as a suitable default */
	plat->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
	500000);
	plat->deactivate_delay_us = fdtdec_get_int(blob, node,
	"spi-deactivate-delay", 0);
	debug("%s: base=%#08lx, periph_id=%d, max-frequency=%d, deactivate_delay=%d\n",
	__func__, plat->base, plat->periph_id, plat->frequency,
	plat->deactivate_delay_us);

	return 0;
	}

	static int tegra114_spi_probe(struct udevice *bus)
	{
	struct tegra_spi_platdata *plat = dev_get_platdata(bus);
	struct tegra114_spi_priv *priv = dev_get_priv(bus);
	struct spi_regs *regs;
	ulong rate;

	priv->regs = (struct spi_regs *)plat->base;
	regs = priv->regs;

	priv->last_transaction_us = timer_get_us();
	priv->freq = plat->frequency;
	priv->periph_id = plat->periph_id;

	/*
	* Change SPI clock to correct frequency, PLLP_OUT0 source, falling
	* back to the oscillator if that is too fast.
	*/
	rate = clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH,
	priv->freq);
	if (rate > priv->freq + 100000) {
	rate = clock_start_periph_pll(priv->periph_id, CLOCK_ID_OSC,
	priv->freq);
	if (rate != priv->freq) {
	printf("Warning: SPI '%s' requested clock %u, actual clock %lu\n",
	bus->name, priv->freq, rate);
	}
	}

	/* Clear stale status here */
	setbits_le32(&regs->fifo_status,
	SPI_FIFO_STS_ERR \|
	SPI_FIFO_STS_TX_FIFO_OVF \|
	SPI_FIFO_STS_TX_FIFO_UNR \|
	SPI_FIFO_STS_RX_FIFO_OVF \|
	SPI_FIFO_STS_RX_FIFO_UNR \|
	SPI_FIFO_STS_TX_FIFO_FULL \|
	SPI_FIFO_STS_TX_FIFO_EMPTY \|
	SPI_FIFO_STS_RX_FIFO_FULL \|
	SPI_FIFO_STS_RX_FIFO_EMPTY);
	debug("%s: FIFO STATUS = %08x\n", __func__, readl(&regs->fifo_status));

	setbits_le32(&priv->regs->command1, SPI_CMD1_M_S \| SPI_CMD1_CS_SW_HW \|
	(priv->mode << SPI_CMD1_MODE_SHIFT) \| SPI_CMD1_CS_SW_VAL);
	debug("%s: COMMAND1 = %08x\n", __func__, readl(&regs->command1));

	return 0;
	}

	/**
	* Activate the CS by driving it LOW
	*
	* @param slave Pointer to spi_slave to which controller has to
	* communicate with
	*/
	static void spi_cs_activate(struct udevice *dev)
	{
	struct udevice *bus = dev->parent;
	struct tegra_spi_platdata *pdata = dev_get_platdata(bus);
	struct tegra114_spi_priv *priv = dev_get_priv(bus);

	/* If it's too soon to do another transaction, wait */
	if (pdata->deactivate_delay_us &&
	priv->last_transaction_us) {
	ulong delay_us; /* The delay completed so far */
	delay_us = timer_get_us() - priv->last_transaction_us;
	if (delay_us < pdata->deactivate_delay_us)
	udelay(pdata->deactivate_delay_us - delay_us);
	}

	clrbits_le32(&priv->regs->command1, SPI_CMD1_CS_SW_VAL);
	}

	/**
	* Deactivate the CS by driving it HIGH
	*
	* @param slave Pointer to spi_slave to which controller has to
	* communicate with
	*/
	static void spi_cs_deactivate(struct udevice *dev)
	{
	struct udevice *bus = dev->parent;
	struct tegra_spi_platdata *pdata = dev_get_platdata(bus);
	struct tegra114_spi_priv *priv = dev_get_priv(bus);

	setbits_le32(&priv->regs->command1, SPI_CMD1_CS_SW_VAL);

	/* Remember time of this transaction so we can honour the bus delay */
	if (pdata->deactivate_delay_us)
	priv->last_transaction_us = timer_get_us();

	debug("Deactivate CS, bus '%s'\n", bus->name);
	}

	static int tegra114_spi_xfer(struct udevice *dev, unsigned int bitlen,
	const void data_out, void data_in,
	unsigned long flags)
	{
	struct udevice *bus = dev->parent;
	struct tegra114_spi_priv *priv = dev_get_priv(bus);
	struct spi_regs *regs = priv->regs;
	u32 reg, tmpdout, tmpdin = 0;
	const u8 *dout = data_out;
	u8 *din = data_in;
	int num_bytes;
	int ret;

	debug("%s: slave %u:%u dout %p din %p bitlen %u\n",
	__func__, bus->seq, spi_chip_select(dev), dout, din, bitlen);
	if (bitlen % 8)
	return -1;
	num_bytes = bitlen / 8;

	ret = 0;

	if (flags & SPI_XFER_BEGIN)
	spi_cs_activate(dev);

	/* clear all error status bits */
	reg = readl(&regs->fifo_status);
	writel(reg, &regs->fifo_status);

	clrsetbits_le32(&regs->command1, SPI_CMD1_CS_SW_VAL,
	SPI_CMD1_RX_EN \| SPI_CMD1_TX_EN \| SPI_CMD1_LSBY_FE \|
	(spi_chip_select(dev) << SPI_CMD1_CS_SEL_SHIFT));

	/* set xfer size to 1 block (32 bits) */
	writel(0, &regs->dma_blk);

	/* handle data in 32-bit chunks */
	while (num_bytes > 0) {
	int bytes;
	int tm, i;

	tmpdout = 0;
	bytes = (num_bytes > 4) ? 4 : num_bytes;

	if (dout != NULL) {
	for (i = 0; i < bytes; ++i)
	tmpdout = (tmpdout << 8) \| dout[i];
	dout += bytes;
	}

	num_bytes -= bytes;

	/* clear ready bit */
	setbits_le32(&regs->xfer_status, SPI_XFER_STS_RDY);

	clrsetbits_le32(&regs->command1,
	SPI_CMD1_BIT_LEN_MASK << SPI_CMD1_BIT_LEN_SHIFT,
	(bytes * 8 - 1) << SPI_CMD1_BIT_LEN_SHIFT);
	writel(tmpdout, &regs->tx_fifo);
	setbits_le32(&regs->command1, SPI_CMD1_GO);

	/*
	* Wait for SPI transmit FIFO to empty, or to time out.
	* The RX FIFO status will be read and cleared last
	*/
	for (tm = 0; tm < SPI_TIMEOUT; ++tm) {
	u32 fifo_status, xfer_status;

	xfer_status = readl(&regs->xfer_status);
	if (!(xfer_status & SPI_XFER_STS_RDY))
	continue;

	fifo_status = readl(&regs->fifo_status);
	if (fifo_status & SPI_FIFO_STS_ERR) {
	debug("%s: got a fifo error: ", __func__);
	if (fifo_status & SPI_FIFO_STS_TX_FIFO_OVF)
	debug("tx FIFO overflow ");
	if (fifo_status & SPI_FIFO_STS_TX_FIFO_UNR)
	debug("tx FIFO underrun ");
	if (fifo_status & SPI_FIFO_STS_RX_FIFO_OVF)
	debug("rx FIFO overflow ");
	if (fifo_status & SPI_FIFO_STS_RX_FIFO_UNR)
	debug("rx FIFO underrun ");
	if (fifo_status & SPI_FIFO_STS_TX_FIFO_FULL)
	debug("tx FIFO full ");
	if (fifo_status & SPI_FIFO_STS_TX_FIFO_EMPTY)
	debug("tx FIFO empty ");
	if (fifo_status & SPI_FIFO_STS_RX_FIFO_FULL)
	debug("rx FIFO full ");
	if (fifo_status & SPI_FIFO_STS_RX_FIFO_EMPTY)
	debug("rx FIFO empty ");
	debug("\n");
	break;
	}

	if (!(fifo_status & SPI_FIFO_STS_RX_FIFO_EMPTY)) {
	tmpdin = readl(&regs->rx_fifo);

	/* swap bytes read in */
	if (din != NULL) {
	for (i = bytes - 1; i >= 0; --i) {
	din[i] = tmpdin & 0xff;
	tmpdin >>= 8;
	}
	din += bytes;
	}

	/* We can exit when we've had both RX and TX */
	break;
	}
	}

	if (tm >= SPI_TIMEOUT)
	ret = tm;

	/* clear ACK RDY, etc. bits */
	writel(readl(&regs->fifo_status), &regs->fifo_status);
	}

	if (flags & SPI_XFER_END)
	spi_cs_deactivate(dev);

	debug("%s: transfer ended. Value=%08x, fifo_status = %08x\n",
	__func__, tmpdin, readl(&regs->fifo_status));

	if (ret) {
	printf("%s: timeout during SPI transfer, tm %d\n",
	__func__, ret);
	return -1;
	}

	return ret;
	}

	static int tegra114_spi_set_speed(struct udevice *bus, uint speed)
	{
	struct tegra_spi_platdata *plat = bus->platdata;
	struct tegra114_spi_priv *priv = dev_get_priv(bus);

	if (speed > plat->frequency)
	speed = plat->frequency;
	priv->freq = speed;
	debug("%s: regs=%p, speed=%d\n", __func__, priv->regs, priv->freq);

	return 0;
	}

	static int tegra114_spi_set_mode(struct udevice *bus, uint mode)
	{
	struct tegra114_spi_priv *priv = dev_get_priv(bus);

	priv->mode = mode;
	debug("%s: regs=%p, mode=%d\n", __func__, priv->regs, priv->mode);

	return 0;
	}

	static const struct dm_spi_ops tegra114_spi_ops = {
	.xfer = tegra114_spi_xfer,
	.set_speed = tegra114_spi_set_speed,
	.set_mode = tegra114_spi_set_mode,
	/*
	* cs_info is not needed, since we require all chip selects to be
	* in the device tree explicitly
	*/
	};

	static const struct udevice_id tegra114_spi_ids[] = {
	{ .compatible = "nvidia,tegra114-spi" },
	{ }
	};

	U_BOOT_DRIVER(tegra114_spi) = {
	.name = "tegra114_spi",
	.id = UCLASS_SPI,
	.of_match = tegra114_spi_ids,
	.ops = &tegra114_spi_ops,
	.ofdata_to_platdata = tegra114_spi_ofdata_to_platdata,
	.platdata_auto_alloc_size = sizeof(struct tegra_spi_platdata),
	.priv_auto_alloc_size = sizeof(struct tegra114_spi_priv),
	.probe = tegra114_spi_probe,
	};