From: Dragos Bogdan <[email protected]> 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 <[email protected]> Signed-off-by: Alexandru Ardelean <[email protected]> --- Changelog v5 -> v6: * https://patchwork.kernel.org/project/spi-devel-general/patch/[email protected]/ * merged on single line message: "setup: can not select any two of dual, quad and no-rx/tx at the same time\n" * not adding Reviewed-by: tag for Andy yet, since there was a nit drivers/spi/spi.c | 25 ++++++++++++++++++++----- include/linux/spi/spi.h | 17 +++++++++++++++++ include/uapi/linux/spi/spi.h | 10 ++++++++++ 3 files changed, 47 insertions(+), 5 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 51d7c004fbab..ca75f4036eda 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -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) 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; diff --git a/include/uapi/linux/spi/spi.h b/include/uapi/linux/spi/spi.h index 703b586f35df..236a85f08ded 100644 --- a/include/uapi/linux/spi/spi.h +++ b/include/uapi/linux/spi/spi.h @@ -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 */ -- 2.17.1
