kernel / drivers / spi / spi-cadence.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Cadence SPI controller driver (host and target mode)
 *
 * Copyright (C) 2008 - 2014 Xilinx, Inc.
 *
 * based on Blackfin On-Chip SPI Driver (spi_bfin5xx.c)
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/spi/spi.h>

/* Name of this driver */
#define CDNS_SPI_NAME		"cdns-spi"

/* Register offset definitions */
#define CDNS_SPI_CR	0x00 /* Configuration  Register, RW */
#define CDNS_SPI_ISR	0x04 /* Interrupt Status Register, RO */
#define CDNS_SPI_IER	0x08 /* Interrupt Enable Register, WO */
#define CDNS_SPI_IDR	0x0c /* Interrupt Disable Register, WO */
#define CDNS_SPI_IMR	0x10 /* Interrupt Enabled Mask Register, RO */
#define CDNS_SPI_ER	0x14 /* Enable/Disable Register, RW */
#define CDNS_SPI_DR	0x18 /* Delay Register, RW */
#define CDNS_SPI_TXD	0x1C /* Data Transmit Register, WO */
#define CDNS_SPI_RXD	0x20 /* Data Receive Register, RO */
#define CDNS_SPI_SICR	0x24 /* Slave Idle Count Register, RW */
#define CDNS_SPI_THLD	0x28 /* Transmit FIFO Watermark Register,RW */

#define SPI_AUTOSUSPEND_TIMEOUT		3000
/*
 * SPI Configuration Register bit Masks
 *
 * This register contains various control bits that affect the operation
 * of the SPI controller
 */
#define CDNS_SPI_CR_MANSTRT	0x00010000 /* Manual TX Start */
#define CDNS_SPI_CR_CPHA		0x00000004 /* Clock Phase Control */
#define CDNS_SPI_CR_CPOL		0x00000002 /* Clock Polarity Control */
#define CDNS_SPI_CR_SSCTRL		0x00003C00 /* Slave Select Mask */
#define CDNS_SPI_CR_PERI_SEL	0x00000200 /* Peripheral Select Decode */
#define CDNS_SPI_CR_BAUD_DIV	0x00000038 /* Baud Rate Divisor Mask */
#define CDNS_SPI_CR_MSTREN		0x00000001 /* Master Enable Mask */
#define CDNS_SPI_CR_MANSTRTEN	0x00008000 /* Manual TX Enable Mask */
#define CDNS_SPI_CR_SSFORCE	0x00004000 /* Manual SS Enable Mask */
#define CDNS_SPI_CR_BAUD_DIV_4	0x00000008 /* Default Baud Div Mask */
#define CDNS_SPI_CR_DEFAULT	(CDNS_SPI_CR_MSTREN | \
					CDNS_SPI_CR_SSCTRL | \
					CDNS_SPI_CR_SSFORCE | \
					CDNS_SPI_CR_BAUD_DIV_4)

/*
 * SPI Configuration Register - Baud rate and target select
 *
 * These are the values used in the calculation of baud rate divisor and
 * setting the target select.
 */

#define CDNS_SPI_BAUD_DIV_MAX		7 /* Baud rate divisor maximum */
#define CDNS_SPI_BAUD_DIV_MIN		1 /* Baud rate divisor minimum */
#define CDNS_SPI_BAUD_DIV_SHIFT		3 /* Baud rate divisor shift in CR */
#define CDNS_SPI_SS_SHIFT		10 /* Slave Select field shift in CR */
#define CDNS_SPI_SS0			0x1 /* Slave Select zero */
#define CDNS_SPI_NOSS			0xF /* No Slave select */

/*
 * SPI Interrupt Registers bit Masks
 *
 * All the four interrupt registers (Status/Mask/Enable/Disable) have the same
 * bit definitions.
 */
#define CDNS_SPI_IXR_TXOW	0x00000004 /* SPI TX FIFO Overwater */
#define CDNS_SPI_IXR_MODF	0x00000002 /* SPI Mode Fault */
#define CDNS_SPI_IXR_RXNEMTY 0x00000010 /* SPI RX FIFO Not Empty */
#define CDNS_SPI_IXR_DEFAULT	(CDNS_SPI_IXR_TXOW | \
					CDNS_SPI_IXR_MODF)
#define CDNS_SPI_IXR_TXFULL	0x00000008 /* SPI TX Full */
#define CDNS_SPI_IXR_ALL	0x0000007F /* SPI all interrupts */

/*
 * SPI Enable Register bit Masks
 *
 * This register is used to enable or disable the SPI controller
 */
#define CDNS_SPI_ER_ENABLE	0x00000001 /* SPI Enable Bit Mask */
#define CDNS_SPI_ER_DISABLE	0x0 /* SPI Disable Bit Mask */

/* Default number of chip select lines */
#define CDNS_SPI_DEFAULT_NUM_CS		4

/**
 * struct cdns_spi - This definition defines spi driver instance
 * @regs:		Virtual address of the SPI controller registers
 * @ref_clk:		Pointer to the peripheral clock
 * @pclk:		Pointer to the APB clock
 * @clk_rate:		Reference clock frequency, taken from @ref_clk
 * @speed_hz:		Current SPI bus clock speed in Hz
 * @txbuf:		Pointer	to the TX buffer
 * @rxbuf:		Pointer to the RX buffer
 * @tx_bytes:		Number of bytes left to transfer
 * @rx_bytes:		Number of bytes requested
 * @n_bytes:		Number of bytes per word
 * @dev_busy:		Device busy flag
 * @is_decoded_cs:	Flag for decoder property set or not
 * @tx_fifo_depth:	Depth of the TX FIFO
 * @rstc:		Optional reset control for SPI controller
 */
struct cdns_spi {
	void __iomem *regs;
	struct clk *ref_clk;
	struct clk *pclk;
	unsigned int clk_rate;
	u32 speed_hz;
	const void *txbuf;
	void *rxbuf;
	int tx_bytes;
	int rx_bytes;
	u8 n_bytes;
	u8 dev_busy;
	u32 is_decoded_cs;
	unsigned int tx_fifo_depth;
	struct reset_control *rstc;
};

enum cdns_spi_frame_n_bytes {
	CDNS_SPI_N_BYTES_NULL = 0,
	CDNS_SPI_N_BYTES_U8 = 1,
	CDNS_SPI_N_BYTES_U16 = 2,
	CDNS_SPI_N_BYTES_U32 = 4
};

/* Macros for the SPI controller read/write */
static inline u32 cdns_spi_read(struct cdns_spi *xspi, u32 offset)
{
	return readl_relaxed(xspi->regs + offset);
}

static inline void cdns_spi_write(struct cdns_spi *xspi, u32 offset, u32 val)
{
	writel_relaxed(val, xspi->regs + offset);
}

/**
 * cdns_spi_init_hw - Initialize the hardware and configure the SPI controller
 * @xspi:	Pointer to the cdns_spi structure
 * @is_target:	Flag to indicate target or host mode
 * * On reset the SPI controller is configured to target or host mode.
 * In host mode baud rate divisor is set to 4, threshold value for TX FIFO
 * not full interrupt is set to 1 and size of the word to be transferred as 8 bit.
 *
 * This function initializes the SPI controller to disable and clear all the
 * interrupts, enable manual target select and manual start, deselect all the
 * chip select lines, and enable the SPI controller.
 */
static void cdns_spi_init_hw(struct cdns_spi *xspi, bool is_target)
{
	u32 ctrl_reg = 0;

	if (!is_target)
		ctrl_reg |= CDNS_SPI_CR_DEFAULT;

	if (xspi->is_decoded_cs)
		ctrl_reg |= CDNS_SPI_CR_PERI_SEL;

	cdns_spi_write(xspi, CDNS_SPI_ER, CDNS_SPI_ER_DISABLE);
	cdns_spi_write(xspi, CDNS_SPI_IDR, CDNS_SPI_IXR_ALL);

	/* Clear the RX FIFO */
	while (cdns_spi_read(xspi, CDNS_SPI_ISR) & CDNS_SPI_IXR_RXNEMTY)
		cdns_spi_read(xspi, CDNS_SPI_RXD);

	cdns_spi_write(xspi, CDNS_SPI_ISR, CDNS_SPI_IXR_ALL);
	cdns_spi_write(xspi, CDNS_SPI_CR, ctrl_reg);
	cdns_spi_write(xspi, CDNS_SPI_ER, CDNS_SPI_ER_ENABLE);
}

/**
 * cdns_spi_chipselect - Select or deselect the chip select line
 * @spi:	Pointer to the spi_device structure
 * @is_high:	Select(0) or deselect (1) the chip select line
 */
static void cdns_spi_chipselect(struct spi_device *spi, bool is_high)
{
	struct cdns_spi *xspi = spi_controller_get_devdata(spi->controller);
	u32 ctrl_reg;

	ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR);

	if (is_high) {
		/* Deselect the target */
		ctrl_reg |= CDNS_SPI_CR_SSCTRL;
	} else {
		/* Select the target */
		ctrl_reg &= ~CDNS_SPI_CR_SSCTRL;
		if (!(xspi->is_decoded_cs))
			ctrl_reg |= ((~(CDNS_SPI_SS0 << spi_get_chipselect(spi, 0))) <<
				     CDNS_SPI_SS_SHIFT) &
				     CDNS_SPI_CR_SSCTRL;
		else
			ctrl_reg |= (spi_get_chipselect(spi, 0) << CDNS_SPI_SS_SHIFT) &
				     CDNS_SPI_CR_SSCTRL;
	}

	cdns_spi_write(xspi, CDNS_SPI_CR, ctrl_reg);
}

/**
 * cdns_spi_config_clock_mode - Sets clock polarity and phase
 * @spi:	Pointer to the spi_device structure
 *
 * Sets the requested clock polarity and phase.
 */
static void cdns_spi_config_clock_mode(struct spi_device *spi)
{
	struct cdns_spi *xspi = spi_controller_get_devdata(spi->controller);
	u32 ctrl_reg, new_ctrl_reg;

	new_ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR);
	ctrl_reg = new_ctrl_reg;

	/* Set the SPI clock phase and clock polarity */
	new_ctrl_reg &= ~(CDNS_SPI_CR_CPHA | CDNS_SPI_CR_CPOL);
	if (spi->mode & SPI_CPHA)
		new_ctrl_reg |= CDNS_SPI_CR_CPHA;
	if (spi->mode & SPI_CPOL)
		new_ctrl_reg |= CDNS_SPI_CR_CPOL;

	if (new_ctrl_reg != ctrl_reg) {
		/*
		 * Just writing the CR register does not seem to apply the clock
		 * setting changes. This is problematic when changing the clock
		 * polarity as it will cause the SPI target to see spurious clock
		 * transitions. To workaround the issue toggle the ER register.
		 */
		cdns_spi_write(xspi, CDNS_SPI_ER, CDNS_SPI_ER_DISABLE);
		cdns_spi_write(xspi, CDNS_SPI_CR, new_ctrl_reg);
		cdns_spi_write(xspi, CDNS_SPI_ER, CDNS_SPI_ER_ENABLE);
	}
}

/**
 * cdns_spi_config_clock_freq - Sets clock frequency
 * @spi:	Pointer to the spi_device structure
 * @transfer:	Pointer to the spi_transfer structure which provides
 *		information about next transfer setup parameters
 *
 * Sets the requested clock frequency.
 * Note: If the requested frequency is not an exact match with what can be
 * obtained using the prescalar value the driver sets the clock frequency which
 * is lower than the requested frequency (maximum lower) for the transfer. If
 * the requested frequency is higher or lower than that is supported by the SPI
 * controller the driver will set the highest or lowest frequency supported by
 * controller.
 */
static void cdns_spi_config_clock_freq(struct spi_device *spi,
				       struct spi_transfer *transfer)
{
	struct cdns_spi *xspi = spi_controller_get_devdata(spi->controller);
	u32 ctrl_reg, baud_rate_val;
	unsigned long frequency;

	frequency = xspi->clk_rate;

	ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR);

	/* Set the clock frequency */
	if (xspi->speed_hz != transfer->speed_hz) {
		/* first valid value is 1 */
		baud_rate_val = CDNS_SPI_BAUD_DIV_MIN;
		while ((baud_rate_val < CDNS_SPI_BAUD_DIV_MAX) &&
		       (frequency / (2 << baud_rate_val)) > transfer->speed_hz)
			baud_rate_val++;

		ctrl_reg &= ~CDNS_SPI_CR_BAUD_DIV;
		ctrl_reg |= baud_rate_val << CDNS_SPI_BAUD_DIV_SHIFT;

		xspi->speed_hz = frequency / (2 << baud_rate_val);
	}
	cdns_spi_write(xspi, CDNS_SPI_CR, ctrl_reg);
}

/**
 * cdns_spi_setup_transfer - Configure SPI controller for specified transfer
 * @spi:	Pointer to the spi_device structure
 * @transfer:	Pointer to the spi_transfer structure which provides
 *		information about next transfer setup parameters
 *
 * Sets the operational mode of SPI controller for the next SPI transfer and
 * sets the requested clock frequency.
 *
 * Return:	Always 0
 */
static int cdns_spi_setup_transfer(struct spi_device *spi,
				   struct spi_transfer *transfer)
{
	struct cdns_spi *xspi = spi_controller_get_devdata(spi->controller);

	cdns_spi_config_clock_freq(spi, transfer);

	dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u clock speed\n",
		__func__, spi->mode, spi->bits_per_word,
		xspi->speed_hz);

	return 0;
}

static u8 cdns_spi_n_bytes(struct spi_transfer *transfer)
{
	if (transfer->bits_per_word <= 8)
		return CDNS_SPI_N_BYTES_U8;
	else if (transfer->bits_per_word <= 16)
		return CDNS_SPI_N_BYTES_U16;
	else
		return CDNS_SPI_N_BYTES_U32;
}

static inline void cdns_spi_reader(struct cdns_spi *xspi)
{
	u32 rxw = 0;

	if (xspi->rxbuf && !IS_ALIGNED((uintptr_t)xspi->rxbuf, xspi->n_bytes)) {
		pr_err("%s: rxbuf address is not aligned for %d bytes\n",
		       __func__, xspi->n_bytes);
		return;
	}

	rxw = cdns_spi_read(xspi, CDNS_SPI_RXD);
	if (xspi->rxbuf) {
		switch (xspi->n_bytes) {
		case CDNS_SPI_N_BYTES_U8:
			*(u8 *)xspi->rxbuf = rxw;
			break;
		case CDNS_SPI_N_BYTES_U16:
			*(u16 *)xspi->rxbuf = rxw;
			break;
		case CDNS_SPI_N_BYTES_U32:
			*(u32 *)xspi->rxbuf = rxw;
			break;
		default:
			pr_err("%s invalid n_bytes %d\n", __func__,
			       xspi->n_bytes);
			return;
		}
		xspi->rxbuf = (u8 *)xspi->rxbuf + xspi->n_bytes;
	}
}

static inline void cdns_spi_writer(struct cdns_spi *xspi)
{
	u32 txw = 0;

	if (xspi->txbuf && !IS_ALIGNED((uintptr_t)xspi->txbuf, xspi->n_bytes)) {
		pr_err("%s: txbuf address is not aligned for %d bytes\n",
		       __func__, xspi->n_bytes);
		return;
	}

	if (xspi->txbuf) {
		switch (xspi->n_bytes) {
		case CDNS_SPI_N_BYTES_U8:
			txw = *(u8 *)xspi->txbuf;
			break;
		case CDNS_SPI_N_BYTES_U16:
			txw = *(u16 *)xspi->txbuf;
			break;
		case CDNS_SPI_N_BYTES_U32:
			txw = *(u32 *)xspi->txbuf;
			break;
		default:
			pr_err("%s invalid n_bytes %d\n", __func__,
			       xspi->n_bytes);
			return;
		}
		cdns_spi_write(xspi, CDNS_SPI_TXD, txw);
		xspi->txbuf = (u8 *)xspi->txbuf + xspi->n_bytes;
	}
}

/**
 * cdns_spi_process_fifo - Fills the TX FIFO, and drain the RX FIFO
 * @xspi:	Pointer to the cdns_spi structure
 * @ntx:	Number of bytes to pack into the TX FIFO
 * @nrx:	Number of bytes to drain from the RX FIFO
 */
static void cdns_spi_process_fifo(struct cdns_spi *xspi, int ntx, int nrx)
{
	ntx = clamp(ntx, 0, xspi->tx_bytes);
	nrx = clamp(nrx, 0, xspi->rx_bytes);

	xspi->tx_bytes -= ntx;
	xspi->rx_bytes -= nrx;

	while (ntx || nrx) {
		if (nrx) {
			cdns_spi_reader(xspi);
			nrx--;
		}

		if (ntx) {
			cdns_spi_writer(xspi);
			ntx--;
		}
	}
}

/**
 * cdns_spi_irq - Interrupt service routine of the SPI controller
 * @irq:	IRQ number
 * @dev_id:	Pointer to the xspi structure
 *
 * This function handles TX empty and Mode Fault interrupts only.
 * On TX empty interrupt this function reads the received data from RX FIFO and
 * fills the TX FIFO if there is any data remaining to be transferred.
 * On Mode Fault interrupt this function indicates that transfer is completed,
 * the SPI subsystem will identify the error as the remaining bytes to be
 * transferred is non-zero.
 *
 * Return:	IRQ_HANDLED when handled; IRQ_NONE otherwise.
 */
static irqreturn_t cdns_spi_irq(int irq, void *dev_id)
{
	struct spi_controller *ctlr = dev_id;
	struct cdns_spi *xspi = spi_controller_get_devdata(ctlr);
	irqreturn_t status;
	u32 intr_status;

	status = IRQ_NONE;
	intr_status = cdns_spi_read(xspi, CDNS_SPI_ISR);
	cdns_spi_write(xspi, CDNS_SPI_ISR, intr_status);

	if (intr_status & CDNS_SPI_IXR_MODF) {
		/* Indicate that transfer is completed, the SPI subsystem will
		 * identify the error as the remaining bytes to be
		 * transferred is non-zero
		 */
		cdns_spi_write(xspi, CDNS_SPI_IDR, CDNS_SPI_IXR_DEFAULT);
		spi_finalize_current_transfer(ctlr);
		status = IRQ_HANDLED;
	} else if (intr_status & CDNS_SPI_IXR_TXOW) {
		int threshold = cdns_spi_read(xspi, CDNS_SPI_THLD);
		int trans_cnt = xspi->rx_bytes - xspi->tx_bytes;

		if (threshold > 1)
			trans_cnt -= threshold;

		/* Set threshold to one if number of pending are
		 * less than half fifo
		 */
		if (xspi->tx_bytes < xspi->tx_fifo_depth >> 1)
			cdns_spi_write(xspi, CDNS_SPI_THLD, 1);

		if (xspi->tx_bytes) {
			cdns_spi_process_fifo(xspi, trans_cnt, trans_cnt);
		} else {
			/* Fixed delay due to controller limitation with
			 * RX_NEMPTY incorrect status
			 * Xilinx AR:65885 contains more details
			 */
			udelay(10);
			cdns_spi_process_fifo(xspi, 0, trans_cnt);
			cdns_spi_write(xspi, CDNS_SPI_IDR,
				       CDNS_SPI_IXR_DEFAULT);
			spi_finalize_current_transfer(ctlr);
		}
		status = IRQ_HANDLED;
	}

	return status;
}

static int cdns_prepare_message(struct spi_controller *ctlr,
				struct spi_message *msg)
{
	if (!spi_controller_is_target(ctlr))
		cdns_spi_config_clock_mode(msg->spi);
	return 0;
}

/**
 * cdns_transfer_one - Initiates the SPI transfer
 * @ctlr:	Pointer to spi_controller structure
 * @spi:	Pointer to the spi_device structure
 * @transfer:	Pointer to the spi_transfer structure which provides
 *		information about next transfer parameters
 *
 * This function in host mode fills the TX FIFO, starts the SPI transfer and
 * returns a positive transfer count so that core will wait for completion.
 * This function in target mode fills the TX FIFO and wait for transfer trigger.
 *
 * Return:	Number of bytes transferred in the last transfer
 */
static int cdns_transfer_one(struct spi_controller *ctlr,
			     struct spi_device *spi,
			     struct spi_transfer *transfer)
{
	struct cdns_spi *xspi = spi_controller_get_devdata(ctlr);

	xspi->txbuf = transfer->tx_buf;
	xspi->rxbuf = transfer->rx_buf;
	xspi->tx_bytes = transfer->len;
	xspi->rx_bytes = transfer->len;

	if (!spi_controller_is_target(ctlr)) {
		cdns_spi_setup_transfer(spi, transfer);
	} else {
		/* Set TX empty threshold to half of FIFO depth
		 * only if TX bytes are more than FIFO depth.
		 */
		if (xspi->tx_bytes > xspi->tx_fifo_depth)
			cdns_spi_write(xspi, CDNS_SPI_THLD, xspi->tx_fifo_depth >> 1);
	}

	/* When xspi in busy condition, bytes may send failed,
	 * then spi control didn't work thoroughly, add one byte delay
	 */
	if (cdns_spi_read(xspi, CDNS_SPI_ISR) & CDNS_SPI_IXR_TXFULL)
		udelay(10);

	xspi->n_bytes = cdns_spi_n_bytes(transfer);
	xspi->tx_bytes = DIV_ROUND_UP(xspi->tx_bytes, xspi->n_bytes);
	xspi->rx_bytes = DIV_ROUND_UP(xspi->rx_bytes, xspi->n_bytes);

	cdns_spi_process_fifo(xspi, xspi->tx_fifo_depth, 0);

	cdns_spi_write(xspi, CDNS_SPI_IER, CDNS_SPI_IXR_DEFAULT);
	return transfer->len;
}

/**
 * cdns_prepare_transfer_hardware - Prepares hardware for transfer.
 * @ctlr:	Pointer to the spi_controller structure which provides
 *		information about the controller.
 *
 * This function enables SPI host controller.
 *
 * Return:	0 always
 */
static int cdns_prepare_transfer_hardware(struct spi_controller *ctlr)
{
	struct cdns_spi *xspi = spi_controller_get_devdata(ctlr);

	cdns_spi_write(xspi, CDNS_SPI_ER, CDNS_SPI_ER_ENABLE);

	return 0;
}

/**
 * cdns_unprepare_transfer_hardware - Relaxes hardware after transfer
 * @ctlr:	Pointer to the spi_controller structure which provides
 *		information about the controller.
 *
 * This function disables the SPI host controller when no target selected.
 * This function flush out if any pending data in FIFO.
 *
 * Return:	0 always
 */
static int cdns_unprepare_transfer_hardware(struct spi_controller *ctlr)
{
	struct cdns_spi *xspi = spi_controller_get_devdata(ctlr);
	u32 ctrl_reg;
	unsigned int cnt = xspi->tx_fifo_depth;

	if (spi_controller_is_target(ctlr)) {
		while (cnt--)
			cdns_spi_read(xspi, CDNS_SPI_RXD);
	}

	/* Disable the SPI if target is deselected */
	ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR);
	ctrl_reg = (ctrl_reg & CDNS_SPI_CR_SSCTRL) >>  CDNS_SPI_SS_SHIFT;
	if (ctrl_reg == CDNS_SPI_NOSS || spi_controller_is_target(ctlr))
		cdns_spi_write(xspi, CDNS_SPI_ER, CDNS_SPI_ER_DISABLE);

	/* Reset to default */
	cdns_spi_write(xspi, CDNS_SPI_THLD, 0x1);
	return 0;
}

/**
 * cdns_spi_detect_fifo_depth - Detect the FIFO depth of the hardware
 * @xspi:	Pointer to the cdns_spi structure
 *
 * The depth of the TX FIFO is a synthesis configuration parameter of the SPI
 * IP. The FIFO threshold register is sized so that its maximum value can be the
 * FIFO size - 1. This is used to detect the size of the FIFO.
 */
static void cdns_spi_detect_fifo_depth(struct cdns_spi *xspi)
{
	/* The MSBs will get truncated giving us the size of the FIFO */
	cdns_spi_write(xspi, CDNS_SPI_THLD, 0xffff);
	xspi->tx_fifo_depth = cdns_spi_read(xspi, CDNS_SPI_THLD) + 1;

	/* Reset to default */
	cdns_spi_write(xspi, CDNS_SPI_THLD, 0x1);
}

/**
 * cdns_target_abort - Abort target transfer
 * @ctlr:	Pointer to the spi_controller structure
 *
 * This function abort target transfer if there any transfer timeout.
 *
 * Return:      0 always
 */
static int cdns_target_abort(struct spi_controller *ctlr)
{
	struct cdns_spi *xspi = spi_controller_get_devdata(ctlr);
	u32 intr_status;

	intr_status = cdns_spi_read(xspi, CDNS_SPI_ISR);
	cdns_spi_write(xspi, CDNS_SPI_ISR, intr_status);
	cdns_spi_write(xspi, CDNS_SPI_IDR, (CDNS_SPI_IXR_MODF | CDNS_SPI_IXR_RXNEMTY));
	spi_finalize_current_transfer(ctlr);

	return 0;
}

/**
 * cdns_spi_probe - Probe method for the SPI driver
 * @pdev:	Pointer to the platform_device structure
 *
 * This function initializes the driver data structures and the hardware.
 *
 * Return:	0 on success and error value on error
 */
static int cdns_spi_probe(struct platform_device *pdev)
{
	int ret = 0, irq;
	struct spi_controller *ctlr;
	struct cdns_spi *xspi;
	u32 num_cs;
	bool target;

	target = of_property_read_bool(pdev->dev.of_node, "spi-slave");
	if (target)
		ctlr = spi_alloc_target(&pdev->dev, sizeof(*xspi));
	else
		ctlr = spi_alloc_host(&pdev->dev, sizeof(*xspi));

	if (!ctlr)
		return -ENOMEM;

	xspi = spi_controller_get_devdata(ctlr);
	ctlr->dev.of_node = pdev->dev.of_node;
	platform_set_drvdata(pdev, ctlr);

	xspi->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(xspi->regs)) {
		ret = PTR_ERR(xspi->regs);
		goto remove_ctlr;
	}

	xspi->pclk = devm_clk_get_enabled(&pdev->dev, "pclk");
	if (IS_ERR(xspi->pclk)) {
		dev_err(&pdev->dev, "pclk clock not found.\n");
		ret = PTR_ERR(xspi->pclk);
		goto remove_ctlr;
	}

	xspi->rstc = devm_reset_control_get_optional_exclusive(&pdev->dev, "spi");
	if (IS_ERR(xspi->rstc)) {
		ret = dev_err_probe(&pdev->dev, PTR_ERR(xspi->rstc),
				    "Cannot get SPI reset.\n");
		goto remove_ctlr;
	}

	reset_control_assert(xspi->rstc);
	reset_control_deassert(xspi->rstc);

	xspi->ref_clk = devm_clk_get_enabled(&pdev->dev, "ref_clk");
	if (IS_ERR(xspi->ref_clk)) {
		dev_err(&pdev->dev, "ref_clk clock not found.\n");
		ret = PTR_ERR(xspi->ref_clk);
		goto remove_ctlr;
	}

	if (!spi_controller_is_target(ctlr)) {
		pm_runtime_use_autosuspend(&pdev->dev);
		pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
		pm_runtime_get_noresume(&pdev->dev);
		pm_runtime_set_active(&pdev->dev);
		pm_runtime_enable(&pdev->dev);

		ret = of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs);
		if (ret < 0)
			ctlr->num_chipselect = CDNS_SPI_DEFAULT_NUM_CS;
		else
			ctlr->num_chipselect = num_cs;

		ret = of_property_read_u32(pdev->dev.of_node, "is-decoded-cs",
					   &xspi->is_decoded_cs);
		if (ret < 0)
			xspi->is_decoded_cs = 0;
	}

	cdns_spi_detect_fifo_depth(xspi);

	/* SPI controller initializations */
	cdns_spi_init_hw(xspi, spi_controller_is_target(ctlr));

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
		ret = irq;
		goto clk_dis_all;
	}

	ret = devm_request_irq(&pdev->dev, irq, cdns_spi_irq,
			       0, pdev->name, ctlr);
	if (ret != 0) {
		ret = -ENXIO;
		dev_err(&pdev->dev, "request_irq failed\n");
		goto clk_dis_all;
	}

	ctlr->use_gpio_descriptors = true;
	ctlr->prepare_transfer_hardware = cdns_prepare_transfer_hardware;
	ctlr->prepare_message = cdns_prepare_message;
	ctlr->transfer_one = cdns_transfer_one;
	ctlr->unprepare_transfer_hardware = cdns_unprepare_transfer_hardware;
	ctlr->mode_bits = SPI_CPOL | SPI_CPHA;
	ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
	ctlr->flags = SPI_CONTROLLER_MUST_TX;

	if (of_device_is_compatible(pdev->dev.of_node, "cix,sky1-spi-r1p6"))
		ctlr->bits_per_word_mask |= SPI_BPW_MASK(16) | SPI_BPW_MASK(32);

	if (!spi_controller_is_target(ctlr)) {
		ctlr->mode_bits |=  SPI_CS_HIGH;
		ctlr->set_cs = cdns_spi_chipselect;
		ctlr->auto_runtime_pm = true;
		xspi->clk_rate = clk_get_rate(xspi->ref_clk);
		/* Set to default valid value */
		ctlr->max_speed_hz = xspi->clk_rate / 4;
		xspi->speed_hz = ctlr->max_speed_hz;
		pm_runtime_put_autosuspend(&pdev->dev);
	} else {
		ctlr->mode_bits |= SPI_NO_CS;
		ctlr->target_abort = cdns_target_abort;
	}
	ret = spi_register_controller(ctlr);
	if (ret) {
		dev_err(&pdev->dev, "spi_register_controller failed\n");
		goto clk_dis_all;
	}

	return ret;

clk_dis_all:
	if (!spi_controller_is_target(ctlr)) {
		pm_runtime_disable(&pdev->dev);
		pm_runtime_set_suspended(&pdev->dev);
	}
remove_ctlr:
	spi_controller_put(ctlr);
	return ret;
}

/**
 * cdns_spi_remove - Remove method for the SPI driver
 * @pdev:	Pointer to the platform_device structure
 *
 * This function is called if a device is physically removed from the system or
 * if the driver module is being unloaded. It frees all resources allocated to
 * the device.
 */
static void cdns_spi_remove(struct platform_device *pdev)
{
	struct spi_controller *ctlr = platform_get_drvdata(pdev);
	struct cdns_spi *xspi = spi_controller_get_devdata(ctlr);

	cdns_spi_write(xspi, CDNS_SPI_ER, CDNS_SPI_ER_DISABLE);

	if (!spi_controller_is_target(ctlr)) {
		pm_runtime_disable(&pdev->dev);
		pm_runtime_set_suspended(&pdev->dev);
	}

	spi_unregister_controller(ctlr);
}

/**
 * cdns_spi_suspend - Suspend method for the SPI driver
 * @dev:	Address of the platform_device structure
 *
 * This function disables the SPI controller and
 * changes the driver state to "suspend"
 *
 * Return:	0 on success and error value on error
 */
static int __maybe_unused cdns_spi_suspend(struct device *dev)
{
	struct spi_controller *ctlr = dev_get_drvdata(dev);

	return spi_controller_suspend(ctlr);
}

/**
 * cdns_spi_resume - Resume method for the SPI driver
 * @dev:	Address of the platform_device structure
 *
 * This function changes the driver state to "ready"
 *
 * Return:	0 on success and error value on error
 */
static int __maybe_unused cdns_spi_resume(struct device *dev)
{
	struct spi_controller *ctlr = dev_get_drvdata(dev);
	struct cdns_spi *xspi = spi_controller_get_devdata(ctlr);

	cdns_spi_init_hw(xspi, spi_controller_is_target(ctlr));
	return spi_controller_resume(ctlr);
}

/**
 * cdns_spi_runtime_resume - Runtime resume method for the SPI driver
 * @dev:	Address of the platform_device structure
 *
 * This function enables the clocks
 *
 * Return:	0 on success and error value on error
 */
static int __maybe_unused cdns_spi_runtime_resume(struct device *dev)
{
	struct spi_controller *ctlr = dev_get_drvdata(dev);
	struct cdns_spi *xspi = spi_controller_get_devdata(ctlr);
	int ret;

	ret = clk_prepare_enable(xspi->pclk);
	if (ret) {
		dev_err(dev, "Cannot enable APB clock.\n");
		return ret;
	}

	ret = clk_prepare_enable(xspi->ref_clk);
	if (ret) {
		dev_err(dev, "Cannot enable device clock.\n");
		clk_disable_unprepare(xspi->pclk);
		return ret;
	}
	return 0;
}

/**
 * cdns_spi_runtime_suspend - Runtime suspend method for the SPI driver
 * @dev:	Address of the platform_device structure
 *
 * This function disables the clocks
 *
 * Return:	Always 0
 */
static int __maybe_unused cdns_spi_runtime_suspend(struct device *dev)
{
	struct spi_controller *ctlr = dev_get_drvdata(dev);
	struct cdns_spi *xspi = spi_controller_get_devdata(ctlr);

	clk_disable_unprepare(xspi->ref_clk);
	clk_disable_unprepare(xspi->pclk);

	return 0;
}

static const struct dev_pm_ops cdns_spi_dev_pm_ops = {
	SET_RUNTIME_PM_OPS(cdns_spi_runtime_suspend,
			   cdns_spi_runtime_resume, NULL)
	SET_SYSTEM_SLEEP_PM_OPS(cdns_spi_suspend, cdns_spi_resume)
};

static const struct of_device_id cdns_spi_of_match[] = {
	{ .compatible = "xlnx,zynq-spi-r1p6" },
	{ .compatible = "cix,sky1-spi-r1p6" },
	{ .compatible = "cdns,spi-r1p6" },
	{ /* end of table */ }
};
MODULE_DEVICE_TABLE(of, cdns_spi_of_match);

/* cdns_spi_driver - This structure defines the SPI subsystem platform driver */
static struct platform_driver cdns_spi_driver = {
	.probe	= cdns_spi_probe,
	.remove = cdns_spi_remove,
	.driver = {
		.name = CDNS_SPI_NAME,
		.of_match_table = cdns_spi_of_match,
		.pm = &cdns_spi_dev_pm_ops,
	},
};

module_platform_driver(cdns_spi_driver);

MODULE_AUTHOR("Xilinx, Inc.");
MODULE_DESCRIPTION("Cadence SPI driver");
MODULE_LICENSE("GPL");