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]>
---
drivers/spi/spi.c | 25 ++++++++++++++++++++-----
include/linux/spi/spi.h | 2 ++
2 files changed, 22 insertions(+), 5 deletions(-)
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;
--
2.17.1
On Wed, Nov 11, 2020 at 4:13 PM Alexandru Ardelean
<[email protected]> wrote:
>
> 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.
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)
--
With Best Regards,
Andy Shevchenko
On Wed, Nov 11, 2020 at 4:45 PM Andy Shevchenko
<[email protected]> wrote:
>
> On Wed, Nov 11, 2020 at 4:13 PM Alexandru Ardelean
> <[email protected]> wrote:
> >
> > 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.
>
> 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