diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/spi/spi_bitbang_txrx.h | 93 | ||||
| -rw-r--r-- | drivers/spi/spi_butterfly.c | 3 | ||||
| -rw-r--r-- | drivers/spi/spi_gpio.c | 3 | ||||
| -rw-r--r-- | drivers/spi/spi_lm70llp.c | 3 | ||||
| -rw-r--r-- | drivers/spi/spi_s3c24xx_gpio.c | 3 | ||||
| -rw-r--r-- | drivers/spi/spi_sh_sci.c | 3 |
6 files changed, 98 insertions, 10 deletions
diff --git a/drivers/spi/spi_bitbang_txrx.h b/drivers/spi/spi_bitbang_txrx.h new file mode 100644 index 000000000000..fc033bbf9180 --- /dev/null +++ b/drivers/spi/spi_bitbang_txrx.h @@ -0,0 +1,93 @@ +/* + * 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. + */ + +/* + * The code that knows what GPIO pins do what should have declared four + * functions, ideally as inlines, before 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; +} diff --git a/drivers/spi/spi_butterfly.c b/drivers/spi/spi_butterfly.c index c2184866fa9c..8b5281281111 100644 --- a/drivers/spi/spi_butterfly.c +++ b/drivers/spi/spi_butterfly.c @@ -149,8 +149,7 @@ static void butterfly_chipselect(struct spi_device *spi, int value) #define spidelay(X) do{}while(0) //#define spidelay ndelay -#define EXPAND_BITBANG_TXRX -#include <linux/spi/spi_bitbang.h> +#include "spi_bitbang_txrx.h" static u32 butterfly_txrx_word_mode0(struct spi_device *spi, diff --git a/drivers/spi/spi_gpio.c b/drivers/spi/spi_gpio.c index 26bd03e61855..7edbd5807e0e 100644 --- a/drivers/spi/spi_gpio.c +++ b/drivers/spi/spi_gpio.c @@ -127,8 +127,7 @@ static inline int getmiso(const struct spi_device *spi) */ #define spidelay(nsecs) do {} while (0) -#define EXPAND_BITBANG_TXRX -#include <linux/spi/spi_bitbang.h> +#include "spi_bitbang_txrx.h" /* * These functions can leverage inline expansion of GPIO calls to shrink diff --git a/drivers/spi/spi_lm70llp.c b/drivers/spi/spi_lm70llp.c index 568c781ad91c..86fb7b5993db 100644 --- a/drivers/spi/spi_lm70llp.c +++ b/drivers/spi/spi_lm70llp.c @@ -174,8 +174,7 @@ static inline int getmiso(struct spi_device *s) } /*--------------------------------------------------------------------*/ -#define EXPAND_BITBANG_TXRX 1 -#include <linux/spi/spi_bitbang.h> +#include "spi_bitbang_txrx.h" static void lm70_chipselect(struct spi_device *spi, int value) { diff --git a/drivers/spi/spi_s3c24xx_gpio.c b/drivers/spi/spi_s3c24xx_gpio.c index bbf9371cd284..8979a75dbd7b 100644 --- a/drivers/spi/spi_s3c24xx_gpio.c +++ b/drivers/spi/spi_s3c24xx_gpio.c @@ -58,8 +58,7 @@ static inline u32 getmiso(struct spi_device *dev) #define spidelay(x) ndelay(x) -#define EXPAND_BITBANG_TXRX -#include <linux/spi/spi_bitbang.h> +#include "spi_bitbang_txrx.h" static u32 s3c2410_spigpio_txrx_mode0(struct spi_device *spi, diff --git a/drivers/spi/spi_sh_sci.c b/drivers/spi/spi_sh_sci.c index a65c12ffa733..a511be7961a0 100644 --- a/drivers/spi/spi_sh_sci.c +++ b/drivers/spi/spi_sh_sci.c @@ -78,8 +78,7 @@ static inline u32 getmiso(struct spi_device *dev) #define spidelay(x) ndelay(x) -#define EXPAND_BITBANG_TXRX -#include <linux/spi/spi_bitbang.h> +#include "spi_bitbang_txrx.h" static u32 sh_sci_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits) |