1
0
mirror of git://projects.qi-hardware.com/openwrt-xburst.git synced 2024-12-19 22:01:53 +02:00
openwrt-xburst/target/linux/generic/patches-2.6.32/920-04-spi-gpio-implement-spi-delay.patch
nbd c5552ad039 rename target/linux/generic-2.6 to generic
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@21952 3c298f89-4303-0410-b956-a3cf2f4a3e73
2010-06-26 20:42:58 +00:00

59 lines
1.7 KiB
Diff

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 <linux/init.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
+#include <linux/delay.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
@@ -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 <linux/spi/spi_bitbang.h>