diff options
Diffstat (limited to 'include/linux/spi/spi_bitbang.h')
| -rw-r--r-- | include/linux/spi/spi_bitbang.h | 101 |
1 files changed, 0 insertions, 101 deletions
diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h index 3274c507b8a..f987a2bee16 100644 --- a/include/linux/spi/spi_bitbang.h +++ b/include/linux/spi/spi_bitbang.h @@ -1,24 +1,6 @@ #ifndef __SPI_BITBANG_H #define __SPI_BITBANG_H -/* - * Mix this utility code with some glue code to get one of several types of - * simple SPI master driver. Two do polled word-at-a-time I/O: - * - * - GPIO/parport bitbangers. Provide chipselect() and txrx_word[](), - * expanding the per-word routines from the inline templates below. - * - * - Drivers for controllers resembling bare shift registers. Provide - * chipselect() and txrx_word[](), with custom setup()/cleanup() methods - * that use your controller's clock and chipselect registers. - * - * Some hardware works well with requests at spi_transfer scope: - * - * - Drivers leveraging smarter hardware, with fifos or DMA; or for half - * duplex (MicroWire) controllers. Provide chipselect() and txrx_bufs(), - * and custom setup()/cleanup() methods. - */ - #include <linux/workqueue.h> struct spi_bitbang { @@ -68,86 +50,3 @@ extern int spi_bitbang_start(struct spi_bitbang *spi); extern int spi_bitbang_stop(struct spi_bitbang *spi); #endif /* __SPI_BITBANG_H */ - -/*-------------------------------------------------------------------------*/ - -#ifdef EXPAND_BITBANG_TXRX - -/* - * The code that knows what GPIO pins do what should have declared four - * functions, ideally as inlines, before #defining EXPAND_BITBANG_TXRX - * and including this header: - * - * void setsck(struct spi_device *, int is_on); - * void setmosi(struct spi_device *, int is_on); - * int getmiso(struct spi_device *); - * void spidelay(unsigned); - * - * setsck()'s is_on parameter is a zero/nonzero boolean. - * - * setmosi()'s is_on parameter is a zero/nonzero boolean. - * - * getmiso() is required to return 0 or 1 only. Any other value is invalid - * and will result in improper operation. - * - * A non-inlined routine would call bitbang_txrx_*() routines. The - * main loop could easily compile down to a handful of instructions, - * especially if the delay is a NOP (to run at peak speed). - * - * Since this is software, the timings may not be exactly what your board's - * chips need ... there may be several reasons you'd need to tweak timings - * in these routines, not just make to make it faster or slower to match a - * particular CPU clock rate. - */ - -static inline u32 -bitbang_txrx_be_cpha0(struct spi_device *spi, - unsigned nsecs, unsigned cpol, - u32 word, u8 bits) -{ - /* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */ - - /* clock starts at inactive polarity */ - for (word <<= (32 - bits); likely(bits); bits--) { - - /* setup MSB (to slave) on trailing edge */ - setmosi(spi, word & (1 << 31)); - spidelay(nsecs); /* T(setup) */ - - setsck(spi, !cpol); - spidelay(nsecs); - - /* sample MSB (from slave) on leading edge */ - word <<= 1; - word |= getmiso(spi); - setsck(spi, cpol); - } - return word; -} - -static inline u32 -bitbang_txrx_be_cpha1(struct spi_device *spi, - unsigned nsecs, unsigned cpol, - u32 word, u8 bits) -{ - /* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */ - - /* clock starts at inactive polarity */ - for (word <<= (32 - bits); likely(bits); bits--) { - - /* setup MSB (to slave) on leading edge */ - setsck(spi, !cpol); - setmosi(spi, word & (1 << 31)); - spidelay(nsecs); /* T(setup) */ - - setsck(spi, cpol); - spidelay(nsecs); - - /* sample MSB (from slave) on trailing edge */ - word <<= 1; - word |= getmiso(spi); - } - return word; -} - -#endif /* EXPAND_BITBANG_TXRX */ |