text: /* SPDX-License-Identifier: GPL-2.0 */
  #ifndef	__SPI_BITBANG_H
  #define	__SPI_BITBANG_H
  
  #include <linux/workqueue.h>
  
  struct spi_bitbang {
  	struct mutex		lock;
  	u8			busy;
  	u8			use_dma;
  	u16			flags;		/* extra spi->mode support */
  
  	struct spi_master	*master;
  
  	/* setup_transfer() changes clock and/or wordsize to match settings
  	 * for this transfer; zeroes restore defaults from spi_device.
  	 */
  	int	(*setup_transfer)(struct spi_device *spi,
  			struct spi_transfer *t);
  
  	void	(*chipselect)(struct spi_device *spi, int is_on);
  #define	BITBANG_CS_ACTIVE	1	/* normally nCS, active low */
  #define	BITBANG_CS_INACTIVE	0
  
  	/* txrx_bufs() may handle dma mapping for transfers that don't
  	 * already have one (transfer.{tx,rx}_dma is zero), or use PIO
  	 */
  	int	(*txrx_bufs)(struct spi_device *spi, struct spi_transfer *t);
  
  	/* txrx_word[SPI_MODE_*]() just looks like a shift register */
  	u32	(*txrx_word[4])(struct spi_device *spi,
  			unsigned nsecs,
  			u32 word, u8 bits, unsigned flags);
  	int	(*set_line_direction)(struct spi_device *spi, bool output);
  };
  
  /* you can call these default bitbang->master methods from your custom
   * methods, if you like.
   */
  extern int spi_bitbang_setup(struct spi_device *spi);
  extern void spi_bitbang_cleanup(struct spi_device *spi);
  extern int spi_bitbang_setup_transfer(struct spi_device *spi,
  				      struct spi_transfer *t);
  
  /* start or stop queue processing */
  extern int spi_bitbang_start(struct spi_bitbang *spi);
  extern void spi_bitbang_stop(struct spi_bitbang *spi);
  
  #endif	/* __SPI_BITBANG_H */
  