#include <linux/platform_device.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>
+#include <linux/delay.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/spi/spi_gpio.h>
-
/*
* This bitbanging SPI host driver should help make systems usable
* when a native hardware SPI engine is not available, perhaps because
}
/*
- * 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.
+ * Generic bit-banged GPIO SPI might free-run at something in the range
+ * 1Mbps ~ 10Mbps (depending on the platform), and some SPI devices may
+ * need to be clocked at a lower rate. ndelay() is often implemented by
+ * udelay() with rounding up, so do the delay only for nsecs >= 500
+ * (<= 1Mbps). The conditional test adds a small overhead.
*/
-#define spidelay(nsecs) do {} while (0)
+
+static inline void spidelay(unsigned long nsecs)
+{
+ if (nsecs >= 500)
+ ndelay(nsecs);
+}
#include "spi-bitbang-txrx.h"