Implement the SPI-GPIO delay function for busses that need speed limitation. --mb --- a/drivers/spi/spi_gpio.c +++ b/drivers/spi/spi_gpio.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -69,6 +70,7 @@ struct spi_gpio { * #define SPI_MOSI_GPIO 120 * #define SPI_SCK_GPIO 121 * #define SPI_N_CHIPSEL 4 + * #undef NEED_SPIDELAY * #include "spi_gpio.c" */ @@ -76,6 +78,7 @@ struct spi_gpio { #define DRIVER_NAME "spi_gpio" #define GENERIC_BITBANG /* vs tight inlines */ +#define NEED_SPIDELAY 1 /* all functions referencing these symbols must define pdata */ #define SPI_MISO_GPIO ((pdata)->miso) @@ -120,12 +123,20 @@ static inline int getmiso(const struct s #undef pdata /* - * NOTE: this clocks "as fast as we can". It "should" be a function of the - * requested device clock. Software overhead means we usually have trouble - * reaching even one Mbit/sec (except when we can inline bitops), so for now - * we'll just assume we never need additional per-bit slowdowns. + * NOTE: to clock "as fast as we can", set spi_device.max_speed_hz + * and spi_transfer.speed_hz to 0. + * Otherwise this is a function of the requested device clock. + * Software overhead means we usually have trouble + * reaching even one Mbit/sec (except when we can inline bitops). So on small + * embedded devices with fast SPI slaves you usually don't need a delay. */ -#define spidelay(nsecs) do {} while (0) +static inline void spidelay(unsigned nsecs) +{ +#ifdef NEED_SPIDELAY + if (unlikely(nsecs)) + ndelay(nsecs); +#endif /* NEED_SPIDELAY */ +} #define EXPAND_BITBANG_TXRX #include ='/cgit/xen/xen/commit/buildconfigs/mk.linux-2.6-xen?id=d0a7aa6a33391fccc6ef4eedd1b54a4cc1171356'>commitdiffstats
path: root/buildconfigs/mk.linux-2.6-xen
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