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@@ -0,0 +1,60 @@
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+Implement the SPI-GPIO delay function for busses that need speed limitation.
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+
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+--mb
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+
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+
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+
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+Index: linux-2.6.28.5/drivers/spi/spi_gpio.c
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+===================================================================
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+--- linux-2.6.28.5.orig/drivers/spi/spi_gpio.c 2009-02-15 18:53:47.000000000 +0100
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++++ linux-2.6.28.5/drivers/spi/spi_gpio.c 2009-02-15 19:08:58.000000000 +0100
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+@@ -21,6 +21,7 @@
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+ #include <linux/init.h>
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+ #include <linux/platform_device.h>
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+ #include <linux/gpio.h>
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++#include <linux/delay.h>
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+
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+ #include <linux/spi/spi.h>
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+ #include <linux/spi/spi_bitbang.h>
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+@@ -69,6 +70,7 @@ struct spi_gpio {
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+ * #define SPI_MOSI_GPIO 120
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+ * #define SPI_SCK_GPIO 121
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+ * #define SPI_N_CHIPSEL 4
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++ * #undef NEED_SPIDELAY
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+ * #include "spi_gpio.c"
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+ */
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+
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+@@ -76,6 +78,7 @@ struct spi_gpio {
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+ #define DRIVER_NAME "spi_gpio"
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+
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+ #define GENERIC_BITBANG /* vs tight inlines */
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++#define NEED_SPIDELAY 1
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+
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+ /* all functions referencing these symbols must define pdata */
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+ #define SPI_MISO_GPIO ((pdata)->miso)
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+@@ -120,12 +123,20 @@ static inline int getmiso(const struct s
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+ #undef pdata
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+
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+ /*
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+- * NOTE: this clocks "as fast as we can". It "should" be a function of the
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+- * requested device clock. Software overhead means we usually have trouble
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+- * reaching even one Mbit/sec (except when we can inline bitops), so for now
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+- * we'll just assume we never need additional per-bit slowdowns.
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++ * NOTE: to clock "as fast as we can", set spi_device.max_speed_hz
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++ * and spi_transfer.speed_hz to 0.
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++ * Otherwise this is a function of the requested device clock.
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++ * Software overhead means we usually have trouble
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++ * reaching even one Mbit/sec (except when we can inline bitops). So on small
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++ * embedded devices with fast SPI slaves you usually don't need a delay.
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+ */
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+-#define spidelay(nsecs) do {} while (0)
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++static inline void spidelay(unsigned nsecs)
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++{
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++#ifdef NEED_SPIDELAY
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++ if (unlikely(nsecs))
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++ ndelay(nsecs);
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++#endif /* NEED_SPIDELAY */
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++}
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+
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+ #define EXPAND_BITBANG_TXRX
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+ #include <linux/spi/spi_bitbang.h>
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Michael Büsch