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 workqueue_struct *workqueue;
   8         struct work_struct      work;
   9
  10         spinlock_t              lock;
  11         struct list_head        queue;
  12         u8                      busy;
  13         u8                      use_dma;
  14         u8                      flags;          /* extra spi->mode support */
  15
  16         struct spi_master       *master;
  17
  18         /* setup_transfer() changes clock and/or wordsize to match settings
  19          * for this transfer; zeroes restore defaults from spi_device.
  20          */
  21         int     (*setup_transfer)(struct spi_device *spi,
  22                         struct spi_transfer *t);
  23
  24         void    (*chipselect)(struct spi_device *spi, int is_on);
  25 #define BITBANG_CS_ACTIVE       1       /* normally nCS, active low */
  26 #define BITBANG_CS_INACTIVE     0
  27
  28         /* txrx_bufs() may handle dma mapping for transfers that don't
  29          * already have one (transfer.{tx,rx}_dma is zero), or use PIO
  30          */
  31         int     (*txrx_bufs)(struct spi_device *spi, struct spi_transfer *t);
  32
  33         /* txrx_word[SPI_MODE_*]() just looks like a shift register */
  34         u32     (*txrx_word[4])(struct spi_device *spi,
  35                         unsigned nsecs,
  36                         u32 word, u8 bits);
  37 };
  38
  39 /* you can call these default bitbang->master methods from your custom
  40  * methods, if you like.
  41  */
  42 extern int spi_bitbang_setup(struct spi_device *spi);
  43 extern void spi_bitbang_cleanup(struct spi_device *spi);
  44 extern int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m);
  45 extern int spi_bitbang_setup_transfer(struct spi_device *spi,
  46                                       struct spi_transfer *t);
  47
  48 /* start or stop queue processing */
  49 extern int spi_bitbang_start(struct spi_bitbang *spi);
  50 extern int spi_bitbang_stop(struct spi_bitbang *spi);
  51
  52 #endif  /* __SPI_BITBANG_H */