include/linux/spi/spi_bitbang.h

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