mirror of
https://github.com/openwrt/openwrt.git
synced 2024-12-23 15:32:33 +00:00
59 lines
1.7 KiB
Diff
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>
|