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authorDragos Bogdan <dragos.bogdan@analog.com>2020-12-21 17:29:35 +0200
committerMark Brown <broonie@kernel.org>2020-12-28 14:21:31 +0000
commitd962608ce2188a1d46ec9d356d6fad5cd6fc0341 (patch)
treee129ab2ad7f2227640351917584bbf0ebb65da6e /include/linux/spi
parentf7005142dacea1769fba0152c493aaa61b33205c (diff)
spi: Add SPI_NO_TX/RX support
Transmit/receive only is a valid SPI mode. For example, the MOSI/TX line might be missing from an ADC while for a DAC the MISO/RX line may be optional. This patch adds these two new modes: SPI_NO_TX and SPI_NO_RX. This way, the drivers will be able to identify if any of these two lines is missing and to adjust the transfers accordingly. Signed-off-by: Dragos Bogdan <dragos.bogdan@analog.com> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com> Link: https://lore.kernel.org/r/20201221152936.53873-2-alexandru.ardelean@analog.com Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'include/linux/spi')
-rw-r--r--include/linux/spi/spi.h17
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index a08c3f37e202..9bfdfaf286eb 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -6,6 +6,7 @@
#ifndef __LINUX_SPI_H
#define __LINUX_SPI_H
+#include <linux/bits.h>
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/slab.h>
@@ -166,6 +167,18 @@ struct spi_device {
u8 chip_select;
u8 bits_per_word;
bool rt;
+#define SPI_NO_TX BIT(31) /* no transmit wire */
+#define SPI_NO_RX BIT(30) /* no receive wire */
+ /*
+ * All bits defined above should be covered by SPI_MODE_KERNEL_MASK.
+ * The SPI_MODE_KERNEL_MASK has the SPI_MODE_USER_MASK counterpart,
+ * which is defined in 'include/uapi/linux/spi/spi.h'.
+ * The bits defined here are from bit 31 downwards, while in
+ * SPI_MODE_USER_MASK are from 0 upwards.
+ * These bits must not overlap. A static assert check should make sure of that.
+ * If adding extra bits, make sure to decrease the bit index below as well.
+ */
+#define SPI_MODE_KERNEL_MASK (~(BIT(30) - 1))
u32 mode;
int irq;
void *controller_state;
@@ -189,6 +202,10 @@ struct spi_device {
*/
};
+/* Make sure that SPI_MODE_KERNEL_MASK & SPI_MODE_USER_MASK don't overlap */
+static_assert((SPI_MODE_KERNEL_MASK & SPI_MODE_USER_MASK) == 0,
+ "SPI_MODE_USER_MASK & SPI_MODE_KERNEL_MASK must not overlap");
+
static inline struct spi_device *to_spi_device(struct device *dev)
{
return dev ? container_of(dev, struct spi_device, dev) : NULL;