| Message ID | 20201111141529.98147-1-alexandru.ardelean@analog.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | spi: Add SPI_NO_TX/RX support | expand |
On Wed, Nov 11, 2020 at 4:13 PM Alexandru Ardelean <alexandru.ardelean@analog.com> wrote: > > From: Dragos Bogdan <dragos.bogdan@analog.com> > > 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. Shouldn't this update a binding documentation? ... > - /* 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 > */ /* * Perhaps switch to proper multi-line comment style * at the same time? */ ... > #define SPI_TX_OCTAL 0x2000 /* transmit with 8 wires */ > #define SPI_RX_OCTAL 0x4000 /* receive with 8 wires */ > #define SPI_3WIRE_HIZ 0x8000 /* high impedance turnaround */ > +#define SPI_NO_TX 0x10000 /* no transmit wire */ > +#define SPI_NO_RX 0x20000 /* no receive wire */ Perhaps switch to use BIT() instead at some point (as a prerequisite patch, for example)
On Wed, Nov 11, 2020 at 4:45 PM Andy Shevchenko <andy.shevchenko@gmail.com> wrote: > > On Wed, Nov 11, 2020 at 4:13 PM Alexandru Ardelean > <alexandru.ardelean@analog.com> wrote: > > > > From: Dragos Bogdan <dragos.bogdan@analog.com> > > > > 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. > > Shouldn't this update a binding documentation? oh, good catch > > ... > > > - /* 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 > > */ > > /* > * Perhaps switch to proper multi-line comment style > * at the same time? > */ ¯\_(ツ)_/¯ Not sure what SPI prefers as multi-line comment style, But ok. > > ... > > > #define SPI_TX_OCTAL 0x2000 /* transmit with 8 wires */ > > #define SPI_RX_OCTAL 0x4000 /* receive with 8 wires */ > > #define SPI_3WIRE_HIZ 0x8000 /* high impedance turnaround */ > > +#define SPI_NO_TX 0x10000 /* no transmit wire */ > > +#define SPI_NO_RX 0x20000 /* no receive wire */ > > Perhaps switch to use BIT() instead at some point (as a prerequisite > patch, for example) I'll leave this up to the maintainer preference. Maybe I'll do it as a second patch here, so that I can be dropped. > > -- > With Best Regards, > Andy Shevchenko
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 22679c8645db..fc12fcf11126 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1934,6 +1934,9 @@ 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: @@ -1955,6 +1958,9 @@ 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: @@ -3275,12 +3281,16 @@ 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 @@ -3294,7 +3304,8 @@ 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. */ @@ -3550,6 +3561,8 @@ 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) @@ -3563,6 +3576,8 @@ 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 99380c0825db..2e9058f79b2d 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -185,6 +185,8 @@ struct spi_device { #define SPI_TX_OCTAL 0x2000 /* transmit with 8 wires */ #define SPI_RX_OCTAL 0x4000 /* receive with 8 wires */ #define SPI_3WIRE_HIZ 0x8000 /* high impedance turnaround */ +#define SPI_NO_TX 0x10000 /* no transmit wire */ +#define SPI_NO_RX 0x20000 /* no receive wire */ int irq; void *controller_state; void *controller_data;