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 v3 -> v4: * https://lore.kernel.org/linux-spi/[email protected]/ * moved SPI_NO_TX + SPI_NO_RX to internal spi.h header * added SPI_MODE_USER_MASK & SPI_MODE_KERNEL_MASK + BUILD_BUG_ON() check drivers/spi/spi.c | 28 +++++++++++++++++++++++----- include/linux/spi/spi.h | 4 ++++ include/uapi/linux/spi/spi.h | 6 ++++++ 3 files changed, 33 insertions(+), 5 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index cd3c395b4e90..8668626c4a46 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 +3335,17 @@ 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 +3359,8 @@ 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. */ @@ -3609,6 +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) @@ -3622,6 +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) @@ -4190,6 +4206,8 @@ static int __init spi_init(void) { int status; + BUILD_BUG_ON(SPI_MODE_USER_MASK & SPI_MODE_KERNEL_MASK); + buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); if (!buf) { status = -ENOMEM; diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index a08c3f37e202..6f1905f729c4 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 +167,9 @@ 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 */ +#define SPI_MODE_KERNEL_MASK (SPI_NO_TX | SPI_NO_RX) u32 mode; int irq; void *controller_state; diff --git a/include/uapi/linux/spi/spi.h b/include/uapi/linux/spi/spi.h index 703b586f35df..e5c58748422e 100644 --- a/include/uapi/linux/spi/spi.h +++ b/include/uapi/linux/spi/spi.h @@ -28,4 +28,10 @@ #define SPI_RX_OCTAL _BITUL(14) /* receive with 8 wires */ #define SPI_3WIRE_HIZ _BITUL(15) /* high impedance turnaround */ +#define SPI_MODE_USER_MASK \ + (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST | \ + SPI_3WIRE | SPI_LOOP | SPI_NO_CS | SPI_READY | \ + SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD | \ + SPI_CS_WORD | SPI_TX_OCTAL | SPI_RX_OCTAL | SPI_3WIRE_HIZ) + #endif /* _UAPI_SPI_H */ -- 2.17.1
