Unverified Commit d962608c authored by Dragos Bogdan's avatar Dragos Bogdan Committed by Mark Brown
Browse files

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: default avatarDragos Bogdan <dragos.bogdan@analog.com>
Signed-off-by: default avatarAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20201221152936.53873-2-alexandru.ardelean@analog.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent f7005142

drivers/spi/spi.c

+20 −5
Original line number Diff line number Diff line
@@ -1941,6 +1941,9 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi, 
	/* Device DUAL/QUAD mode */

	if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {

		switch (value) {

		case 0:

			spi->mode |= SPI_NO_TX;

			break;

		case 1:

			break;

		case 2:
@@ -1962,6 +1965,9 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi, 


	if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {

		switch (value) {

		case 0:

			spi->mode |= SPI_NO_RX;

			break;

		case 1:

			break;

		case 2:
@@ -3329,12 +3335,16 @@ int spi_setup(struct spi_device *spi) 
	unsigned	bad_bits, ugly_bits;

	int		status;



	/* check mode to prevent that DUAL and QUAD set at the same time

	/*

	 * check mode to prevent that any two of DUAL, QUAD and NO_MOSI/MISO

	 * are set at the same time

	 */

	if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||

		((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {

	if ((hweight_long(spi->mode &

		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_NO_TX)) > 1) ||

	    (hweight_long(spi->mode &

		(SPI_RX_DUAL | SPI_RX_QUAD | SPI_NO_RX)) > 1)) {

		dev_err(&spi->dev,

		"setup: can not select dual and quad at the same time\n");

		"setup: can not select any two of dual, quad and no-rx/tx at the same time\n");

		return -EINVAL;

	}

	/* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
@@ -3348,7 +3358,8 @@ int spi_setup(struct spi_device *spi) 
	 * SPI_CS_WORD has a fallback software implementation,

	 * so it is ignored here.

	 */

	bad_bits = spi->mode & ~(spi->controller->mode_bits | SPI_CS_WORD);

	bad_bits = spi->mode & ~(spi->controller->mode_bits | SPI_CS_WORD |

				 SPI_NO_TX | SPI_NO_RX);

	/* nothing prevents from working with active-high CS in case if it

	 * is driven by GPIO.

	 */
@@ -3610,6 +3621,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message) 
		 * 2. check tx/rx_nbits match the mode in spi_device

		 */

		if (xfer->tx_buf) {

			if (spi->mode & SPI_NO_TX)

				return -EINVAL;

			if (xfer->tx_nbits != SPI_NBITS_SINGLE &&

				xfer->tx_nbits != SPI_NBITS_DUAL &&

				xfer->tx_nbits != SPI_NBITS_QUAD)
@@ -3623,6 +3636,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message) 
		}

		/* check transfer rx_nbits */

		if (xfer->rx_buf) {

			if (spi->mode & SPI_NO_RX)

				return -EINVAL;

			if (xfer->rx_nbits != SPI_NBITS_SINGLE &&

				xfer->rx_nbits != SPI_NBITS_DUAL &&

				xfer->rx_nbits != SPI_NBITS_QUAD)

include/linux/spi/spi.h

+17 −0
Original line number Diff line number Diff line
@@ -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;

include/uapi/linux/spi/spi.h

+10 −0
Original line number Diff line number Diff line
@@ -28,4 +28,14 @@ 
#define	SPI_RX_OCTAL		_BITUL(14)	/* receive with 8 wires */

#define	SPI_3WIRE_HIZ		_BITUL(15)	/* high impedance turnaround */



/*

 * All the bits defined above should be covered by SPI_MODE_USER_MASK.

 * The SPI_MODE_USER_MASK has the SPI_MODE_KERNEL_MASK counterpart in

 * 'include/linux/spi/spi.h'. The bits defined here are from bit 0 upwards

 * while in SPI_MODE_KERNEL_MASK they are from the other end downwards.

 * These bits must not overlap. A static assert check should make sure of that.

 * If adding extra bits, make sure to increase the bit index below as well.

 */

#define SPI_MODE_USER_MASK	(_BITUL(16) - 1)



#endif /* _UAPI_SPI_H */