drivers/spi/tegra210_qspi.c - platform/external/u-boot - Gitiles

 /*
  * NVIDIA Tegra210 QSPI controller driver
  *
  * (C) Copyright 2015 NVIDIA Corporation <www.nvidia.com>
  *
  * SPDX-License-Identifier:     GPL-2.0+
  */

 #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 QSPI_CMD1_GO			BIT(31)
 #define QSPI_CMD1_M_S			BIT(30)
 #define QSPI_CMD1_MODE_MASK		GENMASK(1,0)
 #define QSPI_CMD1_MODE_SHIFT		28
 #define QSPI_CMD1_CS_SEL_MASK		GENMASK(1,0)
 #define QSPI_CMD1_CS_SEL_SHIFT		26
 #define QSPI_CMD1_CS_POL_INACTIVE0	BIT(22)
 #define QSPI_CMD1_CS_SW_HW		BIT(21)
 #define QSPI_CMD1_CS_SW_VAL		BIT(20)
 #define QSPI_CMD1_IDLE_SDA_MASK		GENMASK(1,0)
 #define QSPI_CMD1_IDLE_SDA_SHIFT	18
 #define QSPI_CMD1_BIDIR			BIT(17)
 #define QSPI_CMD1_LSBI_FE		BIT(16)
 #define QSPI_CMD1_LSBY_FE		BIT(15)
 #define QSPI_CMD1_BOTH_EN_BIT		BIT(14)
 #define QSPI_CMD1_BOTH_EN_BYTE		BIT(13)
 #define QSPI_CMD1_RX_EN			BIT(12)
 #define QSPI_CMD1_TX_EN			BIT(11)
 #define QSPI_CMD1_PACKED		BIT(5)
 #define QSPI_CMD1_BITLEN_MASK		GENMASK(4,0)
 #define QSPI_CMD1_BITLEN_SHIFT		0

 /* COMMAND2 */
 #define QSPI_CMD2_TX_CLK_TAP_DELAY	BIT(6)
 #define QSPI_CMD2_TX_CLK_TAP_DELAY_MASK	GENMASK(11,6)
 #define QSPI_CMD2_RX_CLK_TAP_DELAY	BIT(0)
 #define QSPI_CMD2_RX_CLK_TAP_DELAY_MASK	GENMASK(5,0)

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

 /* FIFO STATUS */
 #define QSPI_FIFO_STS_CS_INACTIVE	BIT(31)
 #define QSPI_FIFO_STS_FRAME_END		BIT(30)
 #define QSPI_FIFO_STS_RX_FIFO_FLUSH	BIT(15)
 #define QSPI_FIFO_STS_TX_FIFO_FLUSH	BIT(14)
 #define QSPI_FIFO_STS_ERR		BIT(8)
 #define QSPI_FIFO_STS_TX_FIFO_OVF	BIT(7)
 #define QSPI_FIFO_STS_TX_FIFO_UNR	BIT(6)
 #define QSPI_FIFO_STS_RX_FIFO_OVF	BIT(5)
 #define QSPI_FIFO_STS_RX_FIFO_UNR	BIT(4)
 #define QSPI_FIFO_STS_TX_FIFO_FULL	BIT(3)
 #define QSPI_FIFO_STS_TX_FIFO_EMPTY	BIT(2)
 #define QSPI_FIFO_STS_RX_FIFO_FULL	BIT(1)
 #define QSPI_FIFO_STS_RX_FIFO_EMPTY	BIT(0)

 #define QSPI_TIMEOUT		1000

 struct qspi_regs {
 	u32 command1;	/* 000:QSPI_COMMAND1 register */
 	u32 command2;	/* 004:QSPI_COMMAND2 register */
 	u32 timing1;	/* 008:QSPI_CS_TIM1 register */
 	u32 timing2;	/* 00c:QSPI_CS_TIM2 register */
 	u32 xfer_status;/* 010:QSPI_TRANS_STATUS register */
 	u32 fifo_status;/* 014:QSPI_FIFO_STATUS register */
 	u32 tx_data;	/* 018:QSPI_TX_DATA register */
 	u32 rx_data;	/* 01c:QSPI_RX_DATA register */
 	u32 dma_ctl;	/* 020:QSPI_DMA_CTL register */
 	u32 dma_blk;	/* 024:QSPI_DMA_BLK register */
 	u32 rsvd[56];	/* 028-107 reserved */
 	u32 tx_fifo;	/* 108:QSPI_FIFO1 register */
 	u32 rsvd2[31];	/* 10c-187 reserved */
 	u32 rx_fifo;	/* 188:QSPI_FIFO2 register */
 	u32 spare_ctl;	/* 18c:QSPI_SPARE_CTRL register */
 };

 struct tegra210_qspi_priv {
 	struct qspi_regs *regs;
 	unsigned int freq;
 	unsigned int mode;
 	int periph_id;
 	int valid;
 	int last_transaction_us;
 };

 static int tegra210_qspi_ofdata_to_platdata(struct udevice *bus)
 {
 	struct tegra_spi_platdata *plat = bus->platdata;
 	const void *blob = gd->fdt_blob;
 	int node = dev_of_offset(bus);

 	plat->base = devfdt_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 tegra210_qspi_probe(struct udevice *bus)
 {
 	struct tegra_spi_platdata *plat = dev_get_platdata(bus);
 	struct tegra210_qspi_priv *priv = dev_get_priv(bus);

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

 	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 */
 	clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH, priv->freq);

 	return 0;
 }

 static int tegra210_qspi_claim_bus(struct udevice *bus)
 {
 	struct tegra210_qspi_priv *priv = dev_get_priv(bus);
 	struct qspi_regs *regs = priv->regs;

 	/* Change SPI clock to correct frequency, PLLP_OUT0 source */
 	clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH, priv->freq);

 	debug("%s: FIFO STATUS = %08x\n", __func__, readl(&regs->fifo_status));

 	/* Set master mode and sw controlled CS */
 	setbits_le32(&regs->command1, QSPI_CMD1_M_S | QSPI_CMD1_CS_SW_HW |
 		     (priv->mode << QSPI_CMD1_MODE_SHIFT));
 	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 tegra210_qspi_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, QSPI_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 tegra210_qspi_priv *priv = dev_get_priv(bus);

 	setbits_le32(&priv->regs->command1, QSPI_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 tegra210_qspi_xfer(struct udevice *dev, unsigned int bitlen,
 			     const void *data_out, void *data_in,
 			     unsigned long flags)
 {
 	struct udevice *bus = dev->parent;
 	struct tegra210_qspi_priv *priv = dev_get_priv(bus);
 	struct qspi_regs *regs = priv->regs;
 	u32 reg, tmpdout, tmpdin = 0;
 	const u8 *dout = data_out;
 	u8 *din = data_in;
 	int num_bytes, tm, 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;

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

 	/* flush RX/TX FIFOs */
 	setbits_le32(&regs->fifo_status,
 		     (QSPI_FIFO_STS_RX_FIFO_FLUSH |
 		      QSPI_FIFO_STS_TX_FIFO_FLUSH));

 	tm = QSPI_TIMEOUT;
 	while ((tm && readl(&regs->fifo_status) &
 		      (QSPI_FIFO_STS_RX_FIFO_FLUSH |
 		       QSPI_FIFO_STS_TX_FIFO_FLUSH))) {
 		tm--;
 		udelay(1);
 	}

 	if (!tm) {
 		printf("%s: timeout during QSPI FIFO flush!\n",
 		       __func__);
 		return -1;
 	}

 	/*
 	 * Notes:
 	 *   1. don't set LSBY_FE, so no need to swap bytes from/to TX/RX FIFOs;
 	 *   2. don't set RX_EN and TX_EN yet.
 	 *      (SW needs to make sure that while programming the blk_size,
 	 *       tx_en and rx_en bits must be zero)
 	 *      [TODO] I (Yen Lin) have problems when both RX/TX EN bits are set
 	 *	       i.e., both dout and din are not NULL.
 	 */
 	clrsetbits_le32(&regs->command1,
 			(QSPI_CMD1_LSBI_FE | QSPI_CMD1_LSBY_FE |
 			 QSPI_CMD1_RX_EN | QSPI_CMD1_TX_EN),
 			(spi_chip_select(dev) << QSPI_CMD1_CS_SEL_SHIFT));

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

 	if (flags & SPI_XFER_BEGIN)
 		spi_cs_activate(dev);

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

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

 		if (dout != NULL) {
 			memcpy((void *)&tmpdout, (void *)dout, bytes);
 			dout += bytes;
 			num_bytes -= bytes;
 			writel(tmpdout, &regs->tx_fifo);
 			setbits_le32(&regs->command1, QSPI_CMD1_TX_EN);
 		}

 		if (din != NULL)
 			setbits_le32(&regs->command1, QSPI_CMD1_RX_EN);

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

 		clrsetbits_le32(&regs->command1,
 				QSPI_CMD1_BITLEN_MASK << QSPI_CMD1_BITLEN_SHIFT,
 				(bytes * 8 - 1) << QSPI_CMD1_BITLEN_SHIFT);

 		/* Need to stabilize other reg bits before GO bit set.
 		 * As per the TRM:
 		 * "For successful operation at various freq combinations,
 		 * a minimum of 4-5 spi_clk cycle delay might be required
 		 * before enabling the PIO or DMA bits. The worst case delay
 		 * calculation can be done considering slowest qspi_clk as
 		 * 1MHz. Based on that 1us delay should be enough before
 		 * enabling PIO or DMA." Padded another 1us for safety.
 		 */
 		udelay(2);
 		setbits_le32(&regs->command1, QSPI_CMD1_GO);
 		udelay(1);

 		/*
 		 * 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 < QSPI_TIMEOUT; ++tm) {
 			u32 fifo_status, xfer_status;

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

 			fifo_status = readl(&regs->fifo_status);
 			if (fifo_status & QSPI_FIFO_STS_ERR) {
 				debug("%s: got a fifo error: ", __func__);
 				if (fifo_status & QSPI_FIFO_STS_TX_FIFO_OVF)
 					debug("tx FIFO overflow ");
 				if (fifo_status & QSPI_FIFO_STS_TX_FIFO_UNR)
 					debug("tx FIFO underrun ");
 				if (fifo_status & QSPI_FIFO_STS_RX_FIFO_OVF)
 					debug("rx FIFO overflow ");
 				if (fifo_status & QSPI_FIFO_STS_RX_FIFO_UNR)
 					debug("rx FIFO underrun ");
 				if (fifo_status & QSPI_FIFO_STS_TX_FIFO_FULL)
 					debug("tx FIFO full ");
 				if (fifo_status & QSPI_FIFO_STS_TX_FIFO_EMPTY)
 					debug("tx FIFO empty ");
 				if (fifo_status & QSPI_FIFO_STS_RX_FIFO_FULL)
 					debug("rx FIFO full ");
 				if (fifo_status & QSPI_FIFO_STS_RX_FIFO_EMPTY)
 					debug("rx FIFO empty ");
 				debug("\n");
 				break;
 			}

 			if (!(fifo_status & QSPI_FIFO_STS_RX_FIFO_EMPTY)) {
 				tmpdin = readl(&regs->rx_fifo);
 				if (din != NULL) {
 					memcpy(din, &tmpdin, bytes);
 					din += bytes;
 					num_bytes -= bytes;
 				}
 			}
 			break;
 		}

 		if (tm >= QSPI_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 tegra210_qspi_set_speed(struct udevice *bus, uint speed)
 {
 	struct tegra_spi_platdata *plat = bus->platdata;
 	struct tegra210_qspi_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 tegra210_qspi_set_mode(struct udevice *bus, uint mode)
 {
 	struct tegra210_qspi_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 tegra210_qspi_ops = {
 	.claim_bus	= tegra210_qspi_claim_bus,
 	.xfer		= tegra210_qspi_xfer,
 	.set_speed	= tegra210_qspi_set_speed,
 	.set_mode	= tegra210_qspi_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 tegra210_qspi_ids[] = {
 	{ .compatible = "nvidia,tegra210-qspi" },
 	{ }
 };

 U_BOOT_DRIVER(tegra210_qspi) = {
 	.name = "tegra210-qspi",
 	.id = UCLASS_SPI,
 	.of_match = tegra210_qspi_ids,
 	.ops = &tegra210_qspi_ops,
 	.ofdata_to_platdata = tegra210_qspi_ofdata_to_platdata,
 	.platdata_auto_alloc_size = sizeof(struct tegra_spi_platdata),
 	.priv_auto_alloc_size = sizeof(struct tegra210_qspi_priv),
 	.per_child_auto_alloc_size = sizeof(struct spi_slave),
 	.probe = tegra210_qspi_probe,
 };
	/*
	* NVIDIA Tegra210 QSPI controller driver
	*
	* (C) Copyright 2015 NVIDIA Corporation <www.nvidia.com>
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#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 QSPI_CMD1_GO BIT(31)
	#define QSPI_CMD1_M_S BIT(30)
	#define QSPI_CMD1_MODE_MASK GENMASK(1,0)
	#define QSPI_CMD1_MODE_SHIFT 28
	#define QSPI_CMD1_CS_SEL_MASK GENMASK(1,0)
	#define QSPI_CMD1_CS_SEL_SHIFT 26
	#define QSPI_CMD1_CS_POL_INACTIVE0 BIT(22)
	#define QSPI_CMD1_CS_SW_HW BIT(21)
	#define QSPI_CMD1_CS_SW_VAL BIT(20)
	#define QSPI_CMD1_IDLE_SDA_MASK GENMASK(1,0)
	#define QSPI_CMD1_IDLE_SDA_SHIFT 18
	#define QSPI_CMD1_BIDIR BIT(17)
	#define QSPI_CMD1_LSBI_FE BIT(16)
	#define QSPI_CMD1_LSBY_FE BIT(15)
	#define QSPI_CMD1_BOTH_EN_BIT BIT(14)
	#define QSPI_CMD1_BOTH_EN_BYTE BIT(13)
	#define QSPI_CMD1_RX_EN BIT(12)
	#define QSPI_CMD1_TX_EN BIT(11)
	#define QSPI_CMD1_PACKED BIT(5)
	#define QSPI_CMD1_BITLEN_MASK GENMASK(4,0)
	#define QSPI_CMD1_BITLEN_SHIFT 0

	/* COMMAND2 */
	#define QSPI_CMD2_TX_CLK_TAP_DELAY BIT(6)
	#define QSPI_CMD2_TX_CLK_TAP_DELAY_MASK GENMASK(11,6)
	#define QSPI_CMD2_RX_CLK_TAP_DELAY BIT(0)
	#define QSPI_CMD2_RX_CLK_TAP_DELAY_MASK GENMASK(5,0)

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

	/* FIFO STATUS */
	#define QSPI_FIFO_STS_CS_INACTIVE BIT(31)
	#define QSPI_FIFO_STS_FRAME_END BIT(30)
	#define QSPI_FIFO_STS_RX_FIFO_FLUSH BIT(15)
	#define QSPI_FIFO_STS_TX_FIFO_FLUSH BIT(14)
	#define QSPI_FIFO_STS_ERR BIT(8)
	#define QSPI_FIFO_STS_TX_FIFO_OVF BIT(7)
	#define QSPI_FIFO_STS_TX_FIFO_UNR BIT(6)
	#define QSPI_FIFO_STS_RX_FIFO_OVF BIT(5)
	#define QSPI_FIFO_STS_RX_FIFO_UNR BIT(4)
	#define QSPI_FIFO_STS_TX_FIFO_FULL BIT(3)
	#define QSPI_FIFO_STS_TX_FIFO_EMPTY BIT(2)
	#define QSPI_FIFO_STS_RX_FIFO_FULL BIT(1)
	#define QSPI_FIFO_STS_RX_FIFO_EMPTY BIT(0)

	#define QSPI_TIMEOUT 1000

	struct qspi_regs {
	u32 command1; /* 000:QSPI_COMMAND1 register */
	u32 command2; /* 004:QSPI_COMMAND2 register */
	u32 timing1; /* 008:QSPI_CS_TIM1 register */
	u32 timing2; /* 00c:QSPI_CS_TIM2 register */
	u32 xfer_status;/* 010:QSPI_TRANS_STATUS register */
	u32 fifo_status;/* 014:QSPI_FIFO_STATUS register */
	u32 tx_data; /* 018:QSPI_TX_DATA register */
	u32 rx_data; /* 01c:QSPI_RX_DATA register */
	u32 dma_ctl; /* 020:QSPI_DMA_CTL register */
	u32 dma_blk; /* 024:QSPI_DMA_BLK register */
	u32 rsvd[56]; /* 028-107 reserved */
	u32 tx_fifo; /* 108:QSPI_FIFO1 register */
	u32 rsvd2[31]; /* 10c-187 reserved */
	u32 rx_fifo; /* 188:QSPI_FIFO2 register */
	u32 spare_ctl; /* 18c:QSPI_SPARE_CTRL register */
	};

	struct tegra210_qspi_priv {
	struct qspi_regs *regs;
	unsigned int freq;
	unsigned int mode;
	int periph_id;
	int valid;
	int last_transaction_us;
	};

	static int tegra210_qspi_ofdata_to_platdata(struct udevice *bus)
	{
	struct tegra_spi_platdata *plat = bus->platdata;
	const void *blob = gd->fdt_blob;
	int node = dev_of_offset(bus);

	plat->base = devfdt_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 tegra210_qspi_probe(struct udevice *bus)
	{
	struct tegra_spi_platdata *plat = dev_get_platdata(bus);
	struct tegra210_qspi_priv *priv = dev_get_priv(bus);

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

	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 */
	clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH, priv->freq);

	return 0;
	}

	static int tegra210_qspi_claim_bus(struct udevice *bus)
	{
	struct tegra210_qspi_priv *priv = dev_get_priv(bus);
	struct qspi_regs *regs = priv->regs;

	/* Change SPI clock to correct frequency, PLLP_OUT0 source */
	clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH, priv->freq);

	debug("%s: FIFO STATUS = %08x\n", __func__, readl(&regs->fifo_status));

	/* Set master mode and sw controlled CS */
	setbits_le32(&regs->command1, QSPI_CMD1_M_S \| QSPI_CMD1_CS_SW_HW \|
	(priv->mode << QSPI_CMD1_MODE_SHIFT));
	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 tegra210_qspi_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, QSPI_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 tegra210_qspi_priv *priv = dev_get_priv(bus);

	setbits_le32(&priv->regs->command1, QSPI_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 tegra210_qspi_xfer(struct udevice *dev, unsigned int bitlen,
	const void data_out, void data_in,
	unsigned long flags)
	{
	struct udevice *bus = dev->parent;
	struct tegra210_qspi_priv *priv = dev_get_priv(bus);
	struct qspi_regs *regs = priv->regs;
	u32 reg, tmpdout, tmpdin = 0;
	const u8 *dout = data_out;
	u8 *din = data_in;
	int num_bytes, tm, 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;

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

	/* flush RX/TX FIFOs */
	setbits_le32(&regs->fifo_status,
	(QSPI_FIFO_STS_RX_FIFO_FLUSH \|
	QSPI_FIFO_STS_TX_FIFO_FLUSH));

	tm = QSPI_TIMEOUT;
	while ((tm && readl(&regs->fifo_status) &
	(QSPI_FIFO_STS_RX_FIFO_FLUSH \|
	QSPI_FIFO_STS_TX_FIFO_FLUSH))) {
	tm--;
	udelay(1);
	}

	if (!tm) {
	printf("%s: timeout during QSPI FIFO flush!\n",
	__func__);
	return -1;
	}

	/*
	* Notes:
	* 1. don't set LSBY_FE, so no need to swap bytes from/to TX/RX FIFOs;
	* 2. don't set RX_EN and TX_EN yet.
	* (SW needs to make sure that while programming the blk_size,
	* tx_en and rx_en bits must be zero)
	* [TODO] I (Yen Lin) have problems when both RX/TX EN bits are set
	* i.e., both dout and din are not NULL.
	*/
	clrsetbits_le32(&regs->command1,
	(QSPI_CMD1_LSBI_FE \| QSPI_CMD1_LSBY_FE \|
	QSPI_CMD1_RX_EN \| QSPI_CMD1_TX_EN),
	(spi_chip_select(dev) << QSPI_CMD1_CS_SEL_SHIFT));

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

	if (flags & SPI_XFER_BEGIN)
	spi_cs_activate(dev);

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

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

	if (dout != NULL) {
	memcpy((void )&tmpdout, (void )dout, bytes);
	dout += bytes;
	num_bytes -= bytes;
	writel(tmpdout, &regs->tx_fifo);
	setbits_le32(&regs->command1, QSPI_CMD1_TX_EN);
	}

	if (din != NULL)
	setbits_le32(&regs->command1, QSPI_CMD1_RX_EN);

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

	clrsetbits_le32(&regs->command1,
	QSPI_CMD1_BITLEN_MASK << QSPI_CMD1_BITLEN_SHIFT,
	(bytes * 8 - 1) << QSPI_CMD1_BITLEN_SHIFT);

	/* Need to stabilize other reg bits before GO bit set.
	* As per the TRM:
	* "For successful operation at various freq combinations,
	* a minimum of 4-5 spi_clk cycle delay might be required
	* before enabling the PIO or DMA bits. The worst case delay
	* calculation can be done considering slowest qspi_clk as
	* 1MHz. Based on that 1us delay should be enough before
	* enabling PIO or DMA." Padded another 1us for safety.
	*/
	udelay(2);
	setbits_le32(&regs->command1, QSPI_CMD1_GO);
	udelay(1);

	/*
	* 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 < QSPI_TIMEOUT; ++tm) {
	u32 fifo_status, xfer_status;

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

	fifo_status = readl(&regs->fifo_status);
	if (fifo_status & QSPI_FIFO_STS_ERR) {
	debug("%s: got a fifo error: ", __func__);
	if (fifo_status & QSPI_FIFO_STS_TX_FIFO_OVF)
	debug("tx FIFO overflow ");
	if (fifo_status & QSPI_FIFO_STS_TX_FIFO_UNR)
	debug("tx FIFO underrun ");
	if (fifo_status & QSPI_FIFO_STS_RX_FIFO_OVF)
	debug("rx FIFO overflow ");
	if (fifo_status & QSPI_FIFO_STS_RX_FIFO_UNR)
	debug("rx FIFO underrun ");
	if (fifo_status & QSPI_FIFO_STS_TX_FIFO_FULL)
	debug("tx FIFO full ");
	if (fifo_status & QSPI_FIFO_STS_TX_FIFO_EMPTY)
	debug("tx FIFO empty ");
	if (fifo_status & QSPI_FIFO_STS_RX_FIFO_FULL)
	debug("rx FIFO full ");
	if (fifo_status & QSPI_FIFO_STS_RX_FIFO_EMPTY)
	debug("rx FIFO empty ");
	debug("\n");
	break;
	}

	if (!(fifo_status & QSPI_FIFO_STS_RX_FIFO_EMPTY)) {
	tmpdin = readl(&regs->rx_fifo);
	if (din != NULL) {
	memcpy(din, &tmpdin, bytes);
	din += bytes;
	num_bytes -= bytes;
	}
	}
	break;
	}

	if (tm >= QSPI_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 tegra210_qspi_set_speed(struct udevice *bus, uint speed)
	{
	struct tegra_spi_platdata *plat = bus->platdata;
	struct tegra210_qspi_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 tegra210_qspi_set_mode(struct udevice *bus, uint mode)
	{
	struct tegra210_qspi_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 tegra210_qspi_ops = {
	.claim_bus = tegra210_qspi_claim_bus,
	.xfer = tegra210_qspi_xfer,
	.set_speed = tegra210_qspi_set_speed,
	.set_mode = tegra210_qspi_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 tegra210_qspi_ids[] = {
	{ .compatible = "nvidia,tegra210-qspi" },
	{ }
	};

	U_BOOT_DRIVER(tegra210_qspi) = {
	.name = "tegra210-qspi",
	.id = UCLASS_SPI,
	.of_match = tegra210_qspi_ids,
	.ops = &tegra210_qspi_ops,
	.ofdata_to_platdata = tegra210_qspi_ofdata_to_platdata,
	.platdata_auto_alloc_size = sizeof(struct tegra_spi_platdata),
	.priv_auto_alloc_size = sizeof(struct tegra210_qspi_priv),
	.per_child_auto_alloc_size = sizeof(struct spi_slave),
	.probe = tegra210_qspi_probe,
	};