/*

   * Common SPI Interface: Controller-specific definitions
   *

   * (C) Copyright 2001
   * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
   *

   * SPDX-License-Identifier:	GPL-2.0+

   */
  
  #ifndef _SPI_H_
  #define _SPI_H_

  /* SPI mode flags */
  #define	SPI_CPHA	0x01			/* clock phase */
  #define	SPI_CPOL	0x02			/* clock polarity */
  #define	SPI_MODE_0	(0|0)			/* (original MicroWire) */
  #define	SPI_MODE_1	(0|SPI_CPHA)
  #define	SPI_MODE_2	(SPI_CPOL|0)
  #define	SPI_MODE_3	(SPI_CPOL|SPI_CPHA)

  #define	SPI_CS_HIGH	0x04			/* CS active high */

  #define	SPI_LSB_FIRST	0x08			/* per-word bits-on-wire */
  #define	SPI_3WIRE	0x10			/* SI/SO signals shared */
  #define	SPI_LOOP	0x20			/* loopback mode */

  #define	SPI_SLAVE	0x40			/* slave mode */
  #define	SPI_PREAMBLE	0x80			/* Skip preamble bytes */

  /* SPI transfer flags */

  #define SPI_XFER_BEGIN		0x01	/* Assert CS before transfer */
  #define SPI_XFER_END		0x02	/* Deassert CS after transfer */
  #define SPI_XFER_MMAP		0x08	/* Memory Mapped start */
  #define SPI_XFER_MMAP_END	0x10	/* Memory Mapped End */

  #define SPI_XFER_ONCE		(SPI_XFER_BEGIN | SPI_XFER_END)

  #define SPI_XFER_U_PAGE		(1 << 5)

  /* SPI TX operation modes */
  #define SPI_OPM_TX_QPP		1 << 0

  /* SPI RX operation modes */
  #define SPI_OPM_RX_AS		1 << 0
  #define SPI_OPM_RX_DOUT		1 << 1
  #define SPI_OPM_RX_DIO		1 << 2

  #define SPI_OPM_RX_QOF		1 << 3

  #define SPI_OPM_RX_QIOF		1 << 4

  #define SPI_OPM_RX_EXTN		SPI_OPM_RX_AS | SPI_OPM_RX_DOUT | \

  				SPI_OPM_RX_DIO | SPI_OPM_RX_QOF | \
  				SPI_OPM_RX_QIOF

  /* SPI bus connection options */
  #define SPI_CONN_DUAL_SHARED	1 << 0

  #define SPI_CONN_DUAL_SEPARATED	1 << 1

  /* Header byte that marks the start of the message */

  #define SPI_PREAMBLE_END_BYTE	0xec

  #define SPI_DEFAULT_WORDLEN 8

  /**

   * struct spi_slave - Representation of a SPI slave

   *
   * Drivers are expected to extend this with controller-specific data.
   *

   * @bus:		ID of the bus that the slave is attached to.
   * @cs:			ID of the chip select connected to the slave.

   * @op_mode_rx:		SPI RX operation mode.

   * @op_mode_tx:		SPI TX operation mode.

   * @wordlen:		Size of SPI word in number of bits

   * @max_write_size:	If non-zero, the maximum number of bytes which can
   *			be written at once, excluding command bytes.
   * @memory_map:		Address of read-only SPI flash access.

   * @option:		Varies SPI bus options - separate, shared bus.

   * @flags:		Indication of SPI flags.

   */
  struct spi_slave {

  	unsigned int bus;
  	unsigned int cs;

  	u8 op_mode_rx;

  	u8 op_mode_tx;

  	unsigned int wordlen;

  	unsigned int max_write_size;

  	void *memory_map;

  	u8 option;
  	u8 flags;

  };

  /**

   * Initialization, must be called once on start up.

   *
   * TODO: I don't think we really need this.

   */
  void spi_init(void);

  /**
   * spi_do_alloc_slave - Allocate a new SPI slave (internal)
   *
   * Allocate and zero all fields in the spi slave, and set the bus/chip
   * select. Use the helper macro spi_alloc_slave() to call this.
   *

   * @offset:	Offset of struct spi_slave within slave structure.
   * @size:	Size of slave structure.
   * @bus:	Bus ID of the slave chip.
   * @cs:		Chip select ID of the slave chip on the specified bus.

   */
  void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
  			 unsigned int cs);
  
  /**
   * spi_alloc_slave - Allocate a new SPI slave
   *
   * Allocate and zero all fields in the spi slave, and set the bus/chip
   * select.
   *

   * @_struct:	Name of structure to allocate (e.g. struct tegra_spi).
   *		This structure must contain a member 'struct spi_slave *slave'.
   * @bus:	Bus ID of the slave chip.
   * @cs:		Chip select ID of the slave chip on the specified bus.

   */
  #define spi_alloc_slave(_struct, bus, cs) \
  	spi_do_alloc_slave(offsetof(_struct, slave), \
  			    sizeof(_struct), bus, cs)
  
  /**
   * spi_alloc_slave_base - Allocate a new SPI slave with no private data
   *
   * Allocate and zero all fields in the spi slave, and set the bus/chip
   * select.
   *

   * @bus:	Bus ID of the slave chip.
   * @cs:		Chip select ID of the slave chip on the specified bus.

   */
  #define spi_alloc_slave_base(bus, cs) \
  	spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)

  /**

   * Set up communications parameters for a SPI slave.
   *
   * This must be called once for each slave. Note that this function
   * usually doesn't touch any actual hardware, it only initializes the
   * contents of spi_slave so that the hardware can be easily
   * initialized later.
   *

   * @bus:	Bus ID of the slave chip.
   * @cs:		Chip select ID of the slave chip on the specified bus.
   * @max_hz:	Maximum SCK rate in Hz.
   * @mode:	Clock polarity, clock phase and other parameters.

   *
   * Returns: A spi_slave reference that can be used in subsequent SPI
   * calls, or NULL if one or more of the parameters are not supported.
   */
  struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
  		unsigned int max_hz, unsigned int mode);

  /**

   * Free any memory associated with a SPI slave.
   *

   * @slave:	The SPI slave

   */
  void spi_free_slave(struct spi_slave *slave);

  /**

   * Claim the bus and prepare it for communication with a given slave.
   *
   * This must be called before doing any transfers with a SPI slave. It
   * will enable and initialize any SPI hardware as necessary, and make
   * sure that the SCK line is in the correct idle state. It is not
   * allowed to claim the same bus for several slaves without releasing
   * the bus in between.
   *

   * @slave:	The SPI slave

   *
   * Returns: 0 if the bus was claimed successfully, or a negative value
   * if it wasn't.
   */
  int spi_claim_bus(struct spi_slave *slave);

  /**

   * Release the SPI bus
   *
   * This must be called once for every call to spi_claim_bus() after
   * all transfers have finished. It may disable any SPI hardware as
   * appropriate.
   *

   * @slave:	The SPI slave

   */
  void spi_release_bus(struct spi_slave *slave);

  /**

   * Set the word length for SPI transactions
   *
   * Set the word length (number of bits per word) for SPI transactions.
   *
   * @slave:	The SPI slave
   * @wordlen:	The number of bits in a word
   *
   * Returns: 0 on success, -1 on failure.
   */
  int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
  
  /**

   * SPI transfer
   *
   * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
   * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
   *
   * The source of the outgoing bits is the "dout" parameter and the
   * destination of the input bits is the "din" parameter.  Note that "dout"
   * and "din" can point to the same memory location, in which case the
   * input data overwrites the output data (since both are buffered by
   * temporary variables, this is OK).
   *

   * spi_xfer() interface:

   * @slave:	The SPI slave which will be sending/receiving the data.
   * @bitlen:	How many bits to write and read.
   * @dout:	Pointer to a string of bits to send out.  The bits are

   *		held in a byte array and are sent MSB first.

   * @din:	Pointer to a string of bits that will be filled in.
   * @flags:	A bitwise combination of SPI_XFER_* flags.

   *

   * Returns: 0 on success, not 0 on failure

   */

  int  spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
  		void *din, unsigned long flags);

  /**

   * Determine if a SPI chipselect is valid.
   * This function is provided by the board if the low-level SPI driver
   * needs it to determine if a given chipselect is actually valid.
   *
   * Returns: 1 if bus:cs identifies a valid chip on this board, 0
   * otherwise.
   */
  int  spi_cs_is_valid(unsigned int bus, unsigned int cs);

  /**

   * Activate a SPI chipselect.
   * This function is provided by the board code when using a driver
   * that can't control its chipselects automatically (e.g.
   * common/soft_spi.c). When called, it should activate the chip select
   * to the device identified by "slave".
   */
  void spi_cs_activate(struct spi_slave *slave);

  /**

   * Deactivate a SPI chipselect.
   * This function is provided by the board code when using a driver
   * that can't control its chipselects automatically (e.g.
   * common/soft_spi.c). When called, it should deactivate the chip
   * select to the device identified by "slave".
   */
  void spi_cs_deactivate(struct spi_slave *slave);

  /**

   * Set transfer speed.
   * This sets a new speed to be applied for next spi_xfer().

   * @slave:	The SPI slave
   * @hz:		The transfer speed

   */
  void spi_set_speed(struct spi_slave *slave, uint hz);

  /**

   * Write 8 bits, then read 8 bits.

   * @slave:	The SPI slave we're communicating with
   * @byte:	Byte to be written

   *
   * Returns: The value that was read, or a negative value on error.
   *
   * TODO: This function probably shouldn't be inlined.
   */
  static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
  {
  	unsigned char dout[2];
  	unsigned char din[2];
  	int ret;
  
  	dout[0] = byte;
  	dout[1] = 0;

  	ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
  	return ret < 0 ? ret : din[1];
  }

  /**
   * Set up a SPI slave for a particular device tree node
   *
   * This calls spi_setup_slave() with the correct bus number. Call
   * spi_free_slave() to free it later.
   *

   * @param blob:		Device tree blob

   * @param slave_node:	Slave node to use
   * @param spi_node:	SPI peripheral node to use

   * @return pointer to new spi_slave structure
   */

  struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node,
  				      int spi_node);
  
  /**
   * spi_base_setup_slave_fdt() - helper function to set up a SPI slace
   *
   * This decodes SPI properties from the slave node to determine the
   * chip select and SPI parameters.
   *
   * @blob:	Device tree blob
   * @busnum:	Bus number to use
   * @node:	Device tree node for the SPI bus
   */
  struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum,
  					   int node);

  #endif	/* _SPI_H_ */