include/linux/spi/spi_bitbang.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __SPI_BITBANG_H
   3 #define __SPI_BITBANG_H
   4
   5 #include <linux/workqueue.h>
   6
   7 struct spi_bitbang {
   8         struct mutex            lock;
   9         u8                      busy;
  10         u8                      use_dma;
  11         u8                      flags;          /* extra spi->mode support */
  12
  13         struct spi_master       *master;
  14
  15         /* setup_transfer() changes clock and/or wordsize to match settings
  16          * for this transfer; zeroes restore defaults from spi_device.
  17          */
  18         int     (*setup_transfer)(struct spi_device *spi,
  19                         struct spi_transfer *t);
  20
  21         void    (*chipselect)(struct spi_device *spi, int is_on);
  22 #define BITBANG_CS_ACTIVE       1       /* normally nCS, active low */
  23 #define BITBANG_CS_INACTIVE     0
  24
  25         /* txrx_bufs() may handle dma mapping for transfers that don't
  26          * already have one (transfer.{tx,rx}_dma is zero), or use PIO
  27          */
  28         int     (*txrx_bufs)(struct spi_device *spi, struct spi_transfer *t);
  29
  30         /* txrx_word[SPI_MODE_*]() just looks like a shift register */
  31         u32     (*txrx_word[4])(struct spi_device *spi,
  32                         unsigned nsecs,
  33                         u32 word, u8 bits);
  34 };
  35
  36 /* you can call these default bitbang->master methods from your custom
  37  * methods, if you like.
  38  */
  39 extern int spi_bitbang_setup(struct spi_device *spi);
  40 extern void spi_bitbang_cleanup(struct spi_device *spi);
  41 extern int spi_bitbang_setup_transfer(struct spi_device *spi,
  42                                       struct spi_transfer *t);
  43
  44 /* start or stop queue processing */
  45 extern int spi_bitbang_start(struct spi_bitbang *spi);
  46 extern void spi_bitbang_stop(struct spi_bitbang *spi);
  47
  48 #endif  /* __SPI_BITBANG_H */