RE: [RFC PATCH 2/2] spi: spi-mem: Add support for Zynq QSPI controller

[Naga Sureshkumar Relli <nagasure@xxxxxxxxxx>]

Hi Paul,

Thank you very much for your testing.

> -----Original Message-----
> From: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
> Sent: Wednesday, March 13, 2019 2:22 PM
> To: Naga Sureshkumar Relli <nagasure@xxxxxxxxxx>; broonie@xxxxxxxxxx;
> bbrezillon@xxxxxxxxxx
> Cc: richard@xxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-spi@xxxxxxxxxxxxxxx;
> marek.vasut@xxxxxxxxx; linux-mtd@xxxxxxxxxxxxxxxxxxx; nagasuresh12@xxxxxxxxx;
> dwmw2@xxxxxxxxxxxxx; Michal Simek <michals@xxxxxxxxxx>
> Subject: Re: [RFC PATCH 2/2] spi: spi-mem: Add support for Zynq QSPI controller
> 
> Hi,
> 
> On Thu, 2019-02-28 at 12:32 +0530, Naga Sureshkumar Relli wrote:
> > Add support for QSPI controller driver used by Xilinx Zynq SOC.
> 
> I recently gave this a try on a Zynq SoC, configured to use 2 QSPI flash chips (16 MiB each) in
> a dual-stacked configuration.
> 
> It looks like the driver does not support this configuration yet, but I was able to acccess the
> first flash chip properly with it!
Yes, this version is only targeting for single flash chip.
> 
> Do you have plans (or even patches ready) to add support for dual- stacked configurations in
> the near future? I would definitely be interested in testing such patches (and might also have a
> go at implementing the feature if there are no plans on your side for now).
Yes, we have that plan.
Once we are done with this basic support, then the next immediate thing is, to add dual-parallel and
Dual-stacked configurations.

Thanks,
Naga Sureshkumar Relli.
> 
> So this is:
> Tested-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
> 
> Cheers,
> 
> Paul
> 
> > Signed-off-by: Naga Sureshkumar Relli
> > <naga.sureshkumar.relli@xxxxxxxxxx>
> > ---
> >  drivers/spi/Kconfig         |   8 +
> >  drivers/spi/Makefile        |   1 +
> >  drivers/spi/spi-zynq-qspi.c | 780
> > ++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 789 insertions(+)
> >  create mode 100644 drivers/spi/spi-zynq-qspi.c
> >
> > diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index
> > 9f89cb1..f12c880 100644
> > --- a/drivers/spi/Kconfig
> > +++ b/drivers/spi/Kconfig
> > @@ -816,6 +816,14 @@ config SPI_XTENSA_XTFPGA
> >  	  16 bit words in SPI mode 0, automatically asserting CS on transfer
> >  	  start and deasserting on end.
> >
> > +config SPI_ZYNQ_QSPI
> > +	tristate "Xilinx Zynq QSPI controller"
> > +	depends on ARCH_ZYNQ
> > +	help
> > +	  This enables support for the Zynq Quad SPI controller
> > +	  in master mode.
> > +	  This controller only supports SPI memory interface.
> > +
> >  config SPI_ZYNQMP_GQSPI
> >  	tristate "Xilinx ZynqMP GQSPI controller"
> >  	depends on SPI_MASTER && HAS_DMA
> > diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile index
> > f296270..565db4d 100644
> > --- a/drivers/spi/Makefile
> > +++ b/drivers/spi/Makefile
> > @@ -115,6 +115,7 @@ obj-$(CONFIG_SPI_XCOMM)		+= spi-xcomm.o
> >  obj-$(CONFIG_SPI_XILINX)		+= spi-xilinx.o
> >  obj-$(CONFIG_SPI_XLP)			+= spi-xlp.o
> >  obj-$(CONFIG_SPI_XTENSA_XTFPGA)		+= spi-xtensa-xtfpga.o
> > +obj-$(CONFIG_SPI_ZYNQ_QSPI)		+= spi-zynq-qspi.o
> >  obj-$(CONFIG_SPI_ZYNQMP_GQSPI)		+= spi-zynqmp-gqspi.o
> >
> >  # SPI slave protocol handlers
> > diff --git a/drivers/spi/spi-zynq-qspi.c b/drivers/spi/spi-zynq-qspi.c
> > new file mode 100644 index 0000000..87c9ec2
> > --- /dev/null
> > +++ b/drivers/spi/spi-zynq-qspi.c
> > @@ -0,0 +1,780 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2019 Xilinx, Inc.
> > + *
> > + * Author: Naga Sureshkumar Relli <nagasure@xxxxxxxxxx>  */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/gpio.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/of_address.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/spi/spi.h>
> > +#include <linux/workqueue.h>
> > +#include <linux/spi/spi-mem.h>
> > +
> > +/* Register offset definitions */
> > +#define ZYNQ_QSPI_CONFIG_OFFSET		0x00 /* Configuration  Register, RW
> */
> > +#define ZYNQ_QSPI_STATUS_OFFSET		0x04 /* Interrupt Status Register, RO
> */
> > +#define ZYNQ_QSPI_IEN_OFFSET		0x08 /* Interrupt Enable Register,
> WO */
> > +#define ZYNQ_QSPI_IDIS_OFFSET		0x0C /* Interrupt Disable Reg, WO
> */
> > +#define ZYNQ_QSPI_IMASK_OFFSET		0x10 /* Interrupt Enabled Mask
> Reg,RO */
> > +#define ZYNQ_QSPI_ENABLE_OFFSET		0x14 /* Enable/Disable Register, RW
> */
> > +#define ZYNQ_QSPI_DELAY_OFFSET		0x18 /* Delay Register, RW */
> > +#define ZYNQ_QSPI_TXD_00_00_OFFSET	0x1C /* Transmit 4-byte inst, WO */
> > +#define ZYNQ_QSPI_TXD_00_01_OFFSET	0x80 /* Transmit 1-byte inst, WO */
> > +#define ZYNQ_QSPI_TXD_00_10_OFFSET	0x84 /* Transmit 2-byte inst, WO */
> > +#define ZYNQ_QSPI_TXD_00_11_OFFSET	0x88 /* Transmit 3-byte inst, WO */
> > +#define ZYNQ_QSPI_RXD_OFFSET		0x20 /* Data Receive Register, RO */
> > +#define ZYNQ_QSPI_SIC_OFFSET		0x24 /* Slave Idle Count Register,
> RW */
> > +#define ZYNQ_QSPI_TX_THRESH_OFFSET	0x28 /* TX FIFO Watermark Reg,
> RW */
> > +#define ZYNQ_QSPI_RX_THRESH_OFFSET	0x2C /* RX FIFO Watermark Reg,
> RW */
> > +#define ZYNQ_QSPI_GPIO_OFFSET		0x30 /* GPIO Register, RW */
> > +#define ZYNQ_QSPI_LINEAR_CFG_OFFSET	0xA0 /* Linear Adapter Config Ref,
> RW */
> > +#define ZYNQ_QSPI_MOD_ID_OFFSET		0xFC /* Module ID Register, RO */
> > +
> > +/*
> > + * QSPI Configuration Register bit Masks
> > + *
> > + * This register contains various control bits that effect the
> > +operation
> > + * of the QSPI controller
> > + */
> > +#define ZYNQ_QSPI_CONFIG_IFMODE_MASK	0x80000000 /* Flash Memory
> Interface */
> > +#define ZYNQ_QSPI_CONFIG_MANSRT_MASK	0x00010000 /* Manual TX
> Start */
> > +#define ZYNQ_QSPI_CONFIG_MANSRTEN_MASK	0x00008000 /* Enable
> Manual TX Mode */
> > +#define ZYNQ_QSPI_CONFIG_SSFORCE_MASK	0x00004000 /* Manual Chip
> Select */
> > +#define ZYNQ_QSPI_CONFIG_BDRATE_MASK	0x00000038 /* Baud Rate Divisor
> Mask */
> > +#define ZYNQ_QSPI_CONFIG_CPHA_MASK	0x00000004 /* Clock Phase Control
> */
> > +#define ZYNQ_QSPI_CONFIG_CPOL_MASK	0x00000002 /* Clock Polarity Control
> */
> > +#define ZYNQ_QSPI_CONFIG_SSCTRL_MASK	0x00000400 /* Slave Select Mask */
> > +#define ZYNQ_QSPI_CONFIG_FWIDTH_MASK	0x000000C0 /* FIFO width
> */
> > +#define ZYNQ_QSPI_CONFIG_MSTREN_MASK	0x00000001 /* Master Mode
> */
> > +
> > +/*
> > + * QSPI Configuration Register - Baud rate and slave select
> > + *
> > + * These are the values used in the calculation of baud rate divisor
> > +and
> > + * setting the slave select.
> > + */
> > +#define ZYNQ_QSPI_BAUD_DIV_MAX		7 /* Baud rate divisor maximum */
> > +#define ZYNQ_QSPI_BAUD_DIV_SHIFT	3 /* Baud rate divisor shift in CR */
> > +#define ZYNQ_QSPI_SS_SHIFT		10 /* Slave Select field shift in CR */
> > +
> > +/*
> > + * QSPI Interrupt Registers bit Masks
> > + *
> > + * All the four interrupt registers (Status/Mask/Enable/Disable) have
> > +the same
> > + * bit definitions.
> > + */
> > +#define ZYNQ_QSPI_IXR_RX_OVERFLOW_MASK	0x00000001 /* QSPI RX
> FIFO Overflow */
> > +#define ZYNQ_QSPI_IXR_TXNFULL_MASK	0x00000004 /* QSPI TX FIFO
> Overflow */
> > +#define ZYNQ_QSPI_IXR_TXFULL_MASK	0x00000008 /* QSPI TX FIFO is full
> */
> > +#define ZYNQ_QSPI_IXR_RXNEMTY_MASK	0x00000010 /* QSPI RX FIFO Not
> Empty */
> > +#define ZYNQ_QSPI_IXR_RXF_FULL_MASK	0x00000020 /* QSPI RX FIFO is full
> */
> > +#define ZYNQ_QSPI_IXR_TXF_UNDRFLOW_MASK	0x00000040 /* QSPI TX
> FIFO Underflow */
> > +#define ZYNQ_QSPI_IXR_ALL_MASK
> 	(ZYNQ_QSPI_IXR_RX_OVERFLOW_MASK | \
> > +					ZYNQ_QSPI_IXR_TXNFULL_MASK | \
> > +					ZYNQ_QSPI_IXR_TXFULL_MASK | \
> > +					ZYNQ_QSPI_IXR_RXNEMTY_MASK | \
> > +					ZYNQ_QSPI_IXR_RXF_FULL_MASK | \
> > +					ZYNQ_QSPI_IXR_TXF_UNDRFLOW_MASK)
> > +#define ZYNQ_QSPI_IXR_RXTX_MASK
> 	(ZYNQ_QSPI_IXR_TXNFULL_MASK | \
> > +					ZYNQ_QSPI_IXR_RXNEMTY_MASK)
> > +
> > +/*
> > + * QSPI Enable Register bit Masks
> > + *
> > + * This register is used to enable or disable the QSPI controller  */
> > +#define ZYNQ_QSPI_ENABLE_ENABLE_MASK	0x00000001 /* QSPI Enable
> Bit Mask */
> > +
> > +/*
> > + * QSPI Linear Configuration Register
> > + *
> > + * It is named Linear Configuration but it controls other modes when
> > +not in
> > + * linear mode also.
> > + */
> > +#define ZYNQ_QSPI_LCFG_TWO_MEM_MASK	0x40000000 /* LQSPI Two
> memories Mask */
> > +#define ZYNQ_QSPI_LCFG_SEP_BUS_MASK	0x20000000 /* LQSPI Separate bus
> Mask */
> > +#define ZYNQ_QSPI_LCFG_U_PAGE_MASK	0x10000000 /* LQSPI Upper Page
> Mask */
> > +
> > +#define ZYNQ_QSPI_LCFG_DUMMY_SHIFT	8
> > +
> > +#define ZYNQ_QSPI_FAST_READ_QOUT_CODE	0x6B /* read instruction code
> */
> > +#define ZYNQ_QSPI_FIFO_DEPTH		63 /* FIFO depth in words */
> > +#define ZYNQ_QSPI_RX_THRESHOLD		32 /* Rx FIFO threshold level */
> > +#define ZYNQ_QSPI_TX_THRESHOLD		1 /* Tx FIFO threshold level */
> > +
> > +/*
> > + * The modebits configurable by the driver to make the SPI support
> > +different
> > + * data formats
> > + */
> > +#define MODEBITS			(SPI_CPOL | SPI_CPHA)
> > +
> > +/* Default number of chip selects */
> > +#define ZYNQ_QSPI_DEFAULT_NUM_CS	1
> > +
> > +/**
> > + * struct zynq_qspi - Defines qspi driver instance
> > + * @regs:		Virtual address of the QSPI controller registers
> > + * @refclk:		Pointer to the peripheral clock
> > + * @pclk:		Pointer to the APB clock
> > + * @irq:		IRQ number
> > + * @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 left to receive
> > + * @data_completion:	completion structure
> > + */
> > +struct zynq_qspi {
> > +	struct device *dev;
> > +	void __iomem *regs;
> > +	struct clk *refclk;
> > +	struct clk *pclk;
> > +	int irq;
> > +	u8 *txbuf;
> > +	u8 *rxbuf;
> > +	int tx_bytes;
> > +	int rx_bytes;
> > +	struct completion data_completion;
> > +};
> > +
> > +/*
> > + * Inline functions for the QSPI controller read/write  */ static
> > +inline u32 zynq_qspi_read(struct zynq_qspi *xqspi, u32 offset) {
> > +	return readl_relaxed(xqspi->regs + offset); }
> > +
> > +static inline void zynq_qspi_write(struct zynq_qspi *xqspi, u32 offset,
> > +				   u32 val)
> > +{
> > +	writel_relaxed(val, xqspi->regs + offset); }
> > +
> > +/**
> > + * zynq_qspi_init_hw - Initialize the hardware
> > + * @xqspi:	Pointer to the zynq_qspi structure
> > + *
> > + * The default settings of the QSPI controller's configurable
> > +parameters on
> > + * reset are
> > + *	- Master mode
> > + *	- Baud rate divisor is set to 2
> > + *	- Tx threshold set to 1l Rx threshold set to 32
> > + *	- Flash memory interface mode enabled
> > + *	- Size of the word to be transferred as 8 bit
> > + * This function performs the following actions
> > + *	- Disable and clear all the interrupts
> > + *	- Enable manual slave select
> > + *	- Enable manual start
> > + *	- Deselect all the chip select lines
> > + *	- Set the size of the word to be transferred as 32 bit
> > + *	- Set the little endian mode of TX FIFO and
> > + *	- Enable the QSPI controller
> > + */
> > +static void zynq_qspi_init_hw(struct zynq_qspi *xqspi) {
> > +	u32 config_reg;
> > +
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET, 0);
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_IDIS_OFFSET,
> > +ZYNQ_QSPI_IXR_ALL_MASK);
> > +
> > +	/* Disable linear mode as the boot loader may have used it */
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_LINEAR_CFG_OFFSET, 0);
> > +
> > +	/* Clear the RX FIFO */
> > +	while (zynq_qspi_read(xqspi, ZYNQ_QSPI_STATUS_OFFSET) &
> > +			      ZYNQ_QSPI_IXR_RXNEMTY_MASK)
> > +		zynq_qspi_read(xqspi, ZYNQ_QSPI_RXD_OFFSET);
> > +
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_STATUS_OFFSET,
> ZYNQ_QSPI_IXR_ALL_MASK);
> > +	config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_CONFIG_OFFSET);
> > +	config_reg &= ~(ZYNQ_QSPI_CONFIG_MSTREN_MASK |
> > +			ZYNQ_QSPI_CONFIG_CPOL_MASK |
> > +			ZYNQ_QSPI_CONFIG_CPHA_MASK |
> > +			ZYNQ_QSPI_CONFIG_BDRATE_MASK |
> > +			ZYNQ_QSPI_CONFIG_SSFORCE_MASK |
> > +			ZYNQ_QSPI_CONFIG_MANSRTEN_MASK |
> > +			ZYNQ_QSPI_CONFIG_MANSRT_MASK);
> > +	config_reg |= (ZYNQ_QSPI_CONFIG_MSTREN_MASK |
> > +		       ZYNQ_QSPI_CONFIG_SSFORCE_MASK |
> > +		       ZYNQ_QSPI_CONFIG_FWIDTH_MASK |
> > +		       ZYNQ_QSPI_CONFIG_IFMODE_MASK);
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_CONFIG_OFFSET, config_reg);
> > +
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_RX_THRESH_OFFSET,
> > +			ZYNQ_QSPI_RX_THRESHOLD);
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_TX_THRESH_OFFSET,
> > +			ZYNQ_QSPI_TX_THRESHOLD);
> > +
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET,
> > +			ZYNQ_QSPI_ENABLE_ENABLE_MASK);
> > +}
> > +
> > +static int zynq_qspi_check_buswidth(u8 width) {
> > +	switch (width) {
> > +	case 1:
> > +	case 2:
> > +	case 4:
> > +		return 0;
> > +	}
> > +
> > +	return -ENOTSUPP;
> > +}
> > +
> > +static bool zynq_qspi_supports_op(struct spi_mem *mem,
> > +				  const struct spi_mem_op *op)
> > +{
> > +	int ret;
> > +
> > +	ret = zynq_qspi_check_buswidth(op->cmd.buswidth);
> > +
> > +	if (op->addr.nbytes)
> > +		ret |= zynq_qspi_check_buswidth(op->addr.buswidth);
> > +
> > +	if (op->dummy.nbytes)
> > +		ret |= zynq_qspi_check_buswidth(op->dummy.buswidth);
> > +
> > +	if (op->data.nbytes)
> > +		ret |= zynq_qspi_check_buswidth(op->data.buswidth);
> > +
> > +	if (ret)
> > +		return false;
> > +
> > +	/*
> > +	 * The number of address bytes should be equal to or less than 3 bytes.
> > +	 */
> > +	if (op->addr.nbytes > 3)
> > +		return false;
> > +
> > +	return true;
> > +}
> > +
> > +/**
> > + * zynq_qspi_rxfifo_op - Read 1..4 bytes from RxFIFO to RX buffer
> > + * @xqspi:	Pointer to the zynq_qspi structure
> > + * @size:	Number of bytes to be read (1..4)
> > + */
> > +static void zynq_qspi_rxfifo_op(struct zynq_qspi *xqspi, unsigned int
> > +size) {
> > +	u32 data;
> > +
> > +	data = zynq_qspi_read(xqspi, ZYNQ_QSPI_RXD_OFFSET);
> > +
> > +	if (xqspi->rxbuf) {
> > +		memcpy(xqspi->rxbuf, ((u8 *)&data) + 4 - size, size);
> > +		xqspi->rxbuf += size;
> > +	}
> > +
> > +	xqspi->rx_bytes -= size;
> > +	if (xqspi->rx_bytes < 0)
> > +		xqspi->rx_bytes = 0;
> > +}
> > +
> > +/**
> > + * zynq_qspi_txfifo_op - Write 1..4 bytes from TX buffer to TxFIFO
> > + * @xqspi:	Pointer to the zynq_qspi structure
> > + * @size:	Number of bytes to be written (1..4)
> > + */
> > +static void zynq_qspi_txfifo_op(struct zynq_qspi *xqspi, unsigned int
> > +size) {
> > +	static const unsigned int offset[4] = {
> > +		ZYNQ_QSPI_TXD_00_01_OFFSET, ZYNQ_QSPI_TXD_00_10_OFFSET,
> > +		ZYNQ_QSPI_TXD_00_11_OFFSET, ZYNQ_QSPI_TXD_00_00_OFFSET
> };
> > +	u32 data;
> > +
> > +	if (xqspi->txbuf) {
> > +		data = 0xffffffff;
> > +		memcpy(&data, xqspi->txbuf, size);
> > +		xqspi->txbuf += size;
> > +	} else {
> > +		data = 0;
> > +	}
> > +
> > +	xqspi->tx_bytes -= size;
> > +	zynq_qspi_write(xqspi, offset[size - 1], data); }
> > +
> > +/**
> > + * zynq_qspi_chipselect - Select or deselect the chip select line
> > + * @spi:	Pointer to the spi_device structure
> > + * @assert:	1 for select or 0 for deselect the chip select line
> > + */
> > +static void zynq_qspi_chipselect(struct spi_device *spi, bool assert)
> > +{
> > +	struct spi_controller *ctrl = spi->master;
> > +	struct zynq_qspi *xqspi = spi_controller_get_devdata(ctrl);
> > +	u32 config_reg;
> > +
> > +	config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_CONFIG_OFFSET);
> > +	if (assert) {
> > +		/* Select the slave */
> > +		config_reg &= ~ZYNQ_QSPI_CONFIG_SSCTRL_MASK;
> > +		config_reg |= (((~(BIT(spi->chip_select))) <<
> > +				ZYNQ_QSPI_SS_SHIFT) &
> > +				ZYNQ_QSPI_CONFIG_SSCTRL_MASK);
> > +	} else {
> > +		config_reg |= ZYNQ_QSPI_CONFIG_SSCTRL_MASK;
> > +	}
> > +
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_CONFIG_OFFSET, config_reg); }
> > +
> > +/**
> > + * zynq_qspi_config_op - Configure QSPI controller for specified transfer
> > + * @xqspi:	Pointer to the zynq_qspi structure
> > + * @qspi:	Pointer to the spi_device structure
> > + *
> > + * Sets the operational mode of QSPI controller for the next QSPI
> > +transfer and
> > + * sets the requested clock frequency.
> > + *
> > + * Return:	0 on success and -EINVAL on invalid input parameter
> > + *
> > + * 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 QSPI
> > + * controller the driver will set the highest or lowest frequency
> > +supported by
> > + * controller.
> > + */
> > +static int zynq_qspi_config_op(struct zynq_qspi *xqspi, struct
> > +spi_device *spi) {
> > +	u32 config_reg, baud_rate_val = 0;
> > +
> > +	/* Set the clock frequency */
> > +	while ((baud_rate_val < ZYNQ_QSPI_BAUD_DIV_MAX)  &&
> > +	       (clk_get_rate(xqspi->refclk) / (2 << baud_rate_val)) >
> > +		spi->max_speed_hz)
> > +		baud_rate_val++;
> > +	config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_CONFIG_OFFSET);
> > +
> > +	/* Set the QSPI clock phase and clock polarity */
> > +	config_reg &= (~ZYNQ_QSPI_CONFIG_CPHA_MASK) &
> > +		      (~ZYNQ_QSPI_CONFIG_CPOL_MASK);
> > +	if (spi->mode & SPI_CPHA)
> > +		config_reg |= ZYNQ_QSPI_CONFIG_CPHA_MASK;
> > +	if (spi->mode & SPI_CPOL)
> > +		config_reg |= ZYNQ_QSPI_CONFIG_CPOL_MASK;
> > +
> > +	config_reg &= ~ZYNQ_QSPI_CONFIG_BDRATE_MASK;
> > +	config_reg |= (baud_rate_val << ZYNQ_QSPI_BAUD_DIV_SHIFT);
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_CONFIG_OFFSET, config_reg);
> > +
> > +	return 0;
> > +}
> > +
> > +/**
> > + * zynq_qspi_setup - Configure the QSPI controller
> > + * @spi:	Pointer to the spi_device structure
> > + *
> > + * Sets the operational mode of QSPI controller for the next QSPI
> > +transfer, baud
> > + * rate and divisor value to setup the requested qspi clock.
> > + *
> > + * Return:	0 on success and error value on failure
> > + */
> > +static int zynq_qspi_setup_op(struct spi_device *spi) {
> > +	struct spi_controller *ctrl = spi->master;
> > +	struct zynq_qspi *qspi = spi_controller_get_devdata(ctrl);
> > +
> > +	if (ctrl->busy)
> > +		return -EBUSY;
> > +
> > +	clk_enable(qspi->refclk);
> > +	clk_enable(qspi->pclk);
> > +	zynq_qspi_write(qspi, ZYNQ_QSPI_ENABLE_OFFSET,
> > +			ZYNQ_QSPI_ENABLE_ENABLE_MASK);
> > +
> > +	return 0;
> > +}
> > +
> > +/**
> > + * zynq_qspi_write_op - Fills the TX FIFO with as many bytes as possible
> > + * @xqspi:	Pointer to the zynq_qspi structure
> > + * @txcount:	Maximum number of words to write
> > + * @txempty:	Indicates that TxFIFO is empty
> > + */
> > +static void zynq_qspi_write_op(struct zynq_qspi *xqspi, int txcount,
> > +			       bool txempty)
> > +{
> > +	int count, len, k;
> > +
> > +	len = xqspi->tx_bytes;
> > +	if (len && len < 4) {
> > +		/*
> > +		 * We must empty the TxFIFO between accesses to TXD0,
> > +		 * TXD1, TXD2, TXD3.
> > +		 */
> > +		if (txempty)
> > +			zynq_qspi_txfifo_op(xqspi, len);
> > +
> > +		return;
> > +	}
> > +
> > +	count = len / 4;
> > +	if (count > txcount)
> > +		count = txcount;
> > +
> > +	if (xqspi->txbuf) {
> > +		writesl(xqspi->regs + ZYNQ_QSPI_TXD_00_00_OFFSET,
> > +			xqspi->txbuf, count);
> > +		xqspi->txbuf += count * 4;
> > +	} else {
> > +		for (k = 0; k < count; k++)
> > +			writel_relaxed(0, xqspi->regs +
> > +					  ZYNQ_QSPI_TXD_00_00_OFFSET);
> > +	}
> > +
> > +	xqspi->tx_bytes -= count * 4;
> > +}
> > +
> > +/**
> > + * zynq_qspi_read_op - Drains the RX FIFO by as many bytes as possible
> > + * @xqspi:	Pointer to the zynq_qspi structure
> > + * @rxcount:	Maximum number of words to read
> > + */
> > +static void zynq_qspi_read_op(struct zynq_qspi *xqspi, int rxcount) {
> > +	int count, len, k;
> > +
> > +	len = xqspi->rx_bytes - xqspi->tx_bytes;
> > +	count = len / 4;
> > +	if (count > rxcount)
> > +		count = rxcount;
> > +	if (xqspi->rxbuf) {
> > +		readsl(xqspi->regs + ZYNQ_QSPI_RXD_OFFSET,
> > +		       xqspi->rxbuf, count);
> > +		xqspi->rxbuf += count * 4;
> > +	} else {
> > +		for (k = 0; k < count; k++)
> > +			readl_relaxed(xqspi->regs + ZYNQ_QSPI_RXD_OFFSET);
> > +	}
> > +	xqspi->rx_bytes -= count * 4;
> > +	len -= count * 4;
> > +
> > +	if (len && len < 4 && count < rxcount)
> > +		zynq_qspi_rxfifo_op(xqspi, len);
> > +}
> > +
> > +/**
> > + * zynq_qspi_irq - Interrupt service routine of the QSPI controller
> > + * @irq:	IRQ number
> > + * @dev_id:	Pointer to the xqspi structure
> > + *
> > + * This function handles TX empty 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.
> > + *
> > + * Return:	IRQ_HANDLED when interrupt is handled; IRQ_NONE otherwise.
> > + */
> > +static irqreturn_t zynq_qspi_irq(int irq, void *dev_id) {
> > +	u32 intr_status;
> > +	bool txempty;
> > +	struct zynq_qspi *xqspi = (struct zynq_qspi *)dev_id;
> > +
> > +	intr_status = zynq_qspi_read(xqspi, ZYNQ_QSPI_STATUS_OFFSET);
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_STATUS_OFFSET, intr_status);
> > +
> > +	if ((intr_status & ZYNQ_QSPI_IXR_TXNFULL_MASK) ||
> > +	    (intr_status & ZYNQ_QSPI_IXR_RXNEMTY_MASK)) {
> > +		/*
> > +		 * This bit is set when Tx FIFO has < THRESHOLD entries.
> > +		 * We have the THRESHOLD value set to 1,
> > +		 * so this bit indicates Tx FIFO is empty.
> > +		 */
> > +		txempty = !!(intr_status & ZYNQ_QSPI_IXR_TXNFULL_MASK);
> > +		/* Read out the data from the RX FIFO */
> > +		zynq_qspi_read_op(xqspi, ZYNQ_QSPI_RX_THRESHOLD);
> > +		if (xqspi->tx_bytes) {
> > +			/* There is more data to send */
> > +			zynq_qspi_write_op(xqspi, ZYNQ_QSPI_RX_THRESHOLD,
> > +					   txempty);
> > +		} else {
> > +			/*
> > +			 * If transfer and receive is completed then only send
> > +			 * complete signal.
> > +			 */
> > +			if (!xqspi->rx_bytes) {
> > +				zynq_qspi_write(xqspi,
> > +						ZYNQ_QSPI_IDIS_OFFSET,
> > +						ZYNQ_QSPI_IXR_RXTX_MASK);
> > +				complete(&xqspi->data_completion);
> > +			}
> > +		}
> > +		return IRQ_HANDLED;
> > +	}
> > +
> > +	return IRQ_NONE;
> > +}
> > +
> > +/**
> > + * zynq_qspi_exec_mem_op() - Initiates the QSPI transfer
> > + * @mem: the SPI memory
> > + * @op: the memory operation to execute
> > + *
> > + * Executes a memory operation.
> > + *
> > + * This function first selects the chip and starts the memory operation.
> > + *
> > + * Return: 0 in case of success, a negative error code otherwise.
> > + */
> > +static int zynq_qspi_exec_mem_op(struct spi_mem *mem,
> > +				 const struct spi_mem_op *op)
> > +{
> > +	struct zynq_qspi *xqspi = spi_controller_get_devdata(mem->spi->master);
> > +	int err = 0, i;
> > +	u8 *tmpbuf;
> > +
> > +	dev_dbg(xqspi->dev, "cmd:%#x mode:%d.%d.%d.%d\n",
> > +		op->cmd.opcode, op->cmd.buswidth, op->addr.buswidth,
> > +		op->dummy.buswidth, op->data.buswidth);
> > +
> > +	zynq_qspi_chipselect(mem->spi, true);
> > +	zynq_qspi_config_op(xqspi, mem->spi);
> > +
> > +	if (op->cmd.opcode) {
> > +		reinit_completion(&xqspi->data_completion);
> > +		xqspi->txbuf = (u8 *)&op->cmd.opcode;
> > +		xqspi->rxbuf = NULL;
> > +		xqspi->tx_bytes = sizeof(op->cmd.opcode);
> > +		xqspi->rx_bytes = sizeof(op->cmd.opcode);
> > +		zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
> > +		zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
> > +				ZYNQ_QSPI_IXR_RXTX_MASK);
> > +		if (!wait_for_completion_interruptible_timeout(&xqspi->data_completion,
> > +							       msecs_to_jiffies(1000))) {
> > +			err = -ETIMEDOUT;
> > +		}
> > +	}
> > +	zynq_qspi_config_op(xqspi, mem->spi);
> > +	if (op->addr.nbytes) {
> > +		for (i = 0; i < op->addr.nbytes; i++) {
> > +			xqspi->txbuf[i] = op->addr.val >>
> > +					(8 * (op->addr.nbytes - i - 1));
> > +		}
> > +
> > +		reinit_completion(&xqspi->data_completion);
> > +		xqspi->rxbuf = NULL;
> > +		xqspi->tx_bytes = op->addr.nbytes;
> > +		xqspi->rx_bytes = op->addr.nbytes;
> > +		zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
> > +		zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
> > +				ZYNQ_QSPI_IXR_RXTX_MASK);
> > +		if (!wait_for_completion_interruptible_timeout(&xqspi->data_completion,
> > +							       msecs_to_jiffies(1000))) {
> > +			err = -ETIMEDOUT;
> > +		}
> > +	}
> > +	zynq_qspi_config_op(xqspi, mem->spi);
> > +	if (op->dummy.nbytes) {
> > +		tmpbuf = kzalloc(op->dummy.nbytes, GFP_KERNEL);
> > +		memset(tmpbuf, 0xff, op->dummy.nbytes);
> > +		reinit_completion(&xqspi->data_completion);
> > +		xqspi->txbuf = tmpbuf;
> > +		xqspi->rxbuf = NULL;
> > +		xqspi->tx_bytes = op->dummy.nbytes;
> > +		xqspi->rx_bytes = op->dummy.nbytes;
> > +		zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
> > +		zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
> > +				ZYNQ_QSPI_IXR_RXTX_MASK);
> > +		if (!wait_for_completion_interruptible_timeout(&xqspi->data_completion,
> > +							       msecs_to_jiffies(1000))) {
> > +			err = -ETIMEDOUT;
> > +		}
> > +		kfree(tmpbuf);
> > +	}
> > +	zynq_qspi_config_op(xqspi, mem->spi);
> > +	if (op->data.nbytes) {
> > +		reinit_completion(&xqspi->data_completion);
> > +		if (op->data.dir == SPI_MEM_DATA_OUT) {
> > +			xqspi->txbuf = (u8 *)op->data.buf.out;
> > +			xqspi->tx_bytes = op->data.nbytes;
> > +			xqspi->rxbuf = NULL;
> > +			xqspi->rx_bytes = op->data.nbytes;
> > +		} else {
> > +			xqspi->txbuf = NULL;
> > +			xqspi->rxbuf = (u8 *)op->data.buf.in;
> > +			xqspi->rx_bytes = op->data.nbytes;
> > +			xqspi->tx_bytes = op->data.nbytes;
> > +		}
> > +
> > +		zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
> > +		zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
> > +				ZYNQ_QSPI_IXR_RXTX_MASK);
> > +		if (!wait_for_completion_interruptible_timeout(&xqspi->data_completion,
> > +							       msecs_to_jiffies(1000))) {
> > +			err = -ETIMEDOUT;
> > +		}
> > +	}
> > +	zynq_qspi_chipselect(mem->spi, false);
> > +
> > +	return err;
> > +}
> > +
> > +static const struct spi_controller_mem_ops zynq_qspi_mem_ops = {
> > +	.supports_op = zynq_qspi_supports_op,
> > +	.exec_op = zynq_qspi_exec_mem_op,
> > +};
> > +
> > +/**
> > + * zynq_qspi_probe - Probe method for the QSPI 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 failure
> > + */
> > +static int zynq_qspi_probe(struct platform_device *pdev) {
> > +	int ret = 0;
> > +	struct spi_controller *ctlr;
> > +	struct device *dev = &pdev->dev;
> > +	struct device_node *np = dev->of_node;
> > +	struct zynq_qspi *xqspi;
> > +	struct resource *res;
> > +	u32 num_cs;
> > +
> > +	ctlr = spi_alloc_master(&pdev->dev, sizeof(*xqspi));
> > +	if (!ctlr)
> > +		return -ENOMEM;
> > +
> > +	xqspi = spi_controller_get_devdata(ctlr);
> > +	xqspi->dev = dev;
> > +	platform_set_drvdata(pdev, xqspi);
> > +	ctlr->mem_ops = &zynq_qspi_mem_ops;
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	xqspi->regs = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(xqspi->regs)) {
> > +		ret = PTR_ERR(xqspi->regs);
> > +		goto remove_master;
> > +	}
> > +
> > +	xqspi->pclk = devm_clk_get(&pdev->dev, "pclk");
> > +	if (IS_ERR(xqspi->pclk)) {
> > +		dev_err(&pdev->dev, "pclk clock not found.\n");
> > +		ret = PTR_ERR(xqspi->pclk);
> > +		goto remove_master;
> > +	}
> > +
> > +	init_completion(&xqspi->data_completion);
> > +
> > +	xqspi->refclk = devm_clk_get(&pdev->dev, "ref_clk");
> > +	if (IS_ERR(xqspi->refclk)) {
> > +		dev_err(&pdev->dev, "ref_clk clock not found.\n");
> > +		ret = PTR_ERR(xqspi->refclk);
> > +		goto remove_master;
> > +	}
> > +
> > +	ret = clk_prepare_enable(xqspi->pclk);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Unable to enable APB clock.\n");
> > +		goto remove_master;
> > +	}
> > +
> > +	ret = clk_prepare_enable(xqspi->refclk);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Unable to enable device clock.\n");
> > +		goto clk_dis_pclk;
> > +	}
> > +
> > +	/* QSPI controller initializations */
> > +	zynq_qspi_init_hw(xqspi);
> > +
> > +	xqspi->irq = platform_get_irq(pdev, 0);
> > +	if (xqspi->irq <= 0) {
> > +		ret = -ENXIO;
> > +		dev_err(&pdev->dev, "irq resource not found\n");
> > +		goto remove_master;
> > +	}
> > +	ret = devm_request_irq(&pdev->dev, xqspi->irq, zynq_qspi_irq,
> > +			       0, pdev->name, xqspi);
> > +	if (ret != 0) {
> > +		ret = -ENXIO;
> > +		dev_err(&pdev->dev, "request_irq failed\n");
> > +		goto remove_master;
> > +	}
> > +
> > +	ret = of_property_read_u32(pdev->dev.of_node, "num-cs",
> > +				   &num_cs);
> > +	if (ret < 0)
> > +		ctlr->num_chipselect = ZYNQ_QSPI_DEFAULT_NUM_CS;
> > +	else
> > +		ctlr->num_chipselect = num_cs;
> > +	ctlr->mode_bits =  SPI_RX_DUAL | SPI_RX_QUAD |
> > +			    SPI_TX_DUAL | SPI_TX_QUAD;
> > +	ctlr->mem_ops = &zynq_qspi_mem_ops;
> > +	ctlr->setup = zynq_qspi_setup_op;
> > +	ctlr->max_speed_hz = clk_get_rate(xqspi->refclk) / 2;
> > +	ctlr->dev.of_node = np;
> > +	ret = spi_register_controller(ctlr);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "spi_register_master failed\n");
> > +		goto clk_dis_all;
> > +	}
> > +
> > +	return ret;
> > +
> > +clk_dis_all:
> > +	clk_disable_unprepare(xqspi->refclk);
> > +clk_dis_pclk:
> > +	clk_disable_unprepare(xqspi->pclk);
> > +remove_master:
> > +	spi_controller_put(ctlr);
> > +
> > +	return ret;
> > +}
> > +
> > +/**
> > + * zynq_qspi_remove - Remove method for the QSPI 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.
> > + *
> > + * Return:	0 on success and error value on failure
> > + */
> > +static int zynq_qspi_remove(struct platform_device *pdev) {
> > +	struct zynq_qspi *xqspi = platform_get_drvdata(pdev);
> > +
> > +	zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET, 0);
> > +
> > +	clk_disable_unprepare(xqspi->refclk);
> > +	clk_disable_unprepare(xqspi->pclk);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id zynq_qspi_of_match[] = {
> > +	{ .compatible = "xlnx,zynq-qspi-1.0", },
> > +	{ /* end of table */ }
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, zynq_qspi_of_match);
> > +
> > +/*
> > + * zynq_qspi_driver - This structure defines the QSPI platform driver
> > +*/ static struct platform_driver zynq_qspi_driver = {
> > +	.probe = zynq_qspi_probe,
> > +	.remove = zynq_qspi_remove,
> > +	.driver = {
> > +		.name = "zynq-qspi",
> > +		.of_match_table = zynq_qspi_of_match,
> > +	},
> > +};
> > +
> > +module_platform_driver(zynq_qspi_driver);
> > +
> > +MODULE_AUTHOR("Xilinx, Inc.");
> > +MODULE_DESCRIPTION("Xilinx Zynq QSPI driver"); MODULE_LICENSE("GPL");
> --
> Paul Kocialkowski, Bootlin
> Embedded Linux and kernel engineering
> https://bootlin.com