SPI start bit (9 bit) for BBB
SAITOU Toshihide
toshi at ruby.ocn.ne.jp
Sun Dec 30 23:10:19 UTC 2018
On Sun, 30 Dec 2018 10:42:39 -0700, Ian Lepore <ian at freebsd.org> wrote:
> On Mon, 2018-12-31 at 00:33 +0900, SAITOU Toshihide wrote:
>> In 3-line serial protcol, there is a type using additional 1-bit to
>> specify command or data. The BBB can handle this, so I can use with
>> the following patch (unskillful and maybe side effects exist). I
>> hope this will attract someones interest to implement this and also
>> SPI frequency and mode.
>>
>>
>> --- arm/ti/ti_spi.c.orig 2018-12-22 00:47:12.096034000 +0900
>> +++ arm/ti/ti_spi.c 2018-12-30 23:58:00.000000000 +0900
>> @@ -493,6 +493,7 @@ ti_spi_transfer(device_t dev, device_t child,
>> struct s
>> /* Disable the FIFO. */
>> TI_SPI_WRITE(sc, MCSPI_XFERLEVEL, 0);
>>
>> +#if 0
>> /* 8 bits word, d0 miso, d1 mosi, mode 0 and CS active low.
>> */
>> reg = TI_SPI_READ(sc, MCSPI_CONF_CH(sc->sc_cs));
>> reg &= ~(MCSPI_CONF_FFER | MCSPI_CONF_FFEW |
>> MCSPI_CONF_SBPOL |
>> @@ -501,6 +502,7 @@ ti_spi_transfer(device_t dev, device_t child,
>> struct s
>> MCSPI_CONF_DMAW | MCSPI_CONF_EPOL);
>> reg |= MCSPI_CONF_DPE0 | MCSPI_CONF_EPOL |
>> MCSPI_CONF_WL8BITS;
>> TI_SPI_WRITE(sc, MCSPI_CONF_CH(sc->sc_cs), reg);
>> +#endif
>>
>> #if 0
>> /* Enable channel interrupts. */
>> @@ -558,6 +560,70 @@ ti_spi_get_node(device_t bus, device_t dev)
>> return (ofw_bus_get_node(bus));
>> }
>>
>> +static int
>> +ti_spi_sbe(device_t dev, device_t child, uint32_t *request)
>> +{
>> + struct ti_spi_softc *sc;
>> + uint32_t reg;
>> +
>> + sc = device_get_softc(dev);
>> +
>> + TI_SPI_LOCK(sc);
>> +
>> + /* If the controller is in use wait until it is available.
>> */
>> + while (sc->sc_flags & TI_SPI_BUSY)
>> + mtx_sleep(dev, &sc->sc_mtx, 0, "ti_spi", 0);
>> +
>> + /* Now we have control over SPI controller. */
>> + sc->sc_flags = TI_SPI_BUSY;
>> +
>> + reg = TI_SPI_READ(sc, MCSPI_CONF_CH(sc->sc_cs));
>> + if (*request)
>> + reg |= MCSPI_CONF_SBE;
>> + else
>> + reg &= ~MCSPI_CONF_SBE;
>> + TI_SPI_WRITE(sc, MCSPI_CONF_CH(sc->sc_cs), reg);
>> +
>> + /* Release the controller and wakeup the next thread waiting
>> for it. */
>> + sc->sc_flags = 0;
>> + wakeup_one(dev);
>> + TI_SPI_UNLOCK(sc);
>> +
>> + return (0);
>> +}
>> +
>> +static int
>> +ti_spi_sbpol(device_t dev, device_t child, uint32_t *request)
>> +{
>> + struct ti_spi_softc *sc;
>> + uint32_t reg;
>> +
>> + sc = device_get_softc(dev);
>> +
>> + TI_SPI_LOCK(sc);
>> +
>> + /* If the controller is in use wait until it is available.
>> */
>> + while (sc->sc_flags & TI_SPI_BUSY)
>> + mtx_sleep(dev, &sc->sc_mtx, 0, "ti_spi", 0);
>> +
>> + /* Now we have control over SPI controller. */
>> + sc->sc_flags = TI_SPI_BUSY;
>> +
>> + reg = TI_SPI_READ(sc, MCSPI_CONF_CH(sc->sc_cs));
>> + if (*request)
>> + reg |= MCSPI_CONF_SBPOL;
>> + else
>> + reg &= ~MCSPI_CONF_SBPOL;
>> + TI_SPI_WRITE(sc, MCSPI_CONF_CH(sc->sc_cs), reg);
>> +
>> + /* Release the controller and wakeup the next thread waiting
>> for it. */
>> + sc->sc_flags = 0;
>> + wakeup_one(dev);
>> + TI_SPI_UNLOCK(sc);
>> +
>> + return (0);
>> +}
>> +
>> static device_method_t ti_spi_methods[] = {
>> /* Device interface */
>> DEVMETHOD(device_probe, ti_spi_probe),
>> @@ -569,6 +635,10 @@ static device_method_t ti_spi_methods[] = {
>>
>> /* ofw_bus interface */
>> DEVMETHOD(ofw_bus_get_node, ti_spi_get_node),
>> +
>> + /* provisional chip register interface for SBE and SBPOL */
>> + DEVMETHOD(spibus_sbe, ti_spi_sbe),
>> + DEVMETHOD(spibus_sbpol, ti_spi_sbpol),
>>
>> DEVMETHOD_END
>> };
>> --- dev/spibus/spibus.c.orig 2018-12-29 23:50:40.262296000
>> +0900
>> +++ dev/spibus/spibus.c 2018-12-30 23:58:00.000000000 +0900
>> @@ -226,6 +226,18 @@ spibus_transfer_impl(device_t dev, device_t
>> child, str
>> return (SPIBUS_TRANSFER(device_get_parent(dev), child,
>> cmd));
>> }
>>
>> +static int
>> +spibus_sbe_impl(device_t dev, device_t child, uint32_t *request)
>> +{
>> + return (SPIBUS_SBE(device_get_parent(dev), child, request));
>> +}
>> +
>> +static int
>> +spibus_sbpol_impl(device_t dev, device_t child, uint32_t *request)
>> +{
>> + return (SPIBUS_SBPOL(device_get_parent(dev), child,
>> request));
>> +}
>> +
>> static device_method_t spibus_methods[] = {
>> /* Device interface */
>> DEVMETHOD(device_probe, spibus_probe),
>> @@ -247,6 +259,9 @@ static device_method_t spibus_methods[] = {
>>
>> /* spibus interface */
>> DEVMETHOD(spibus_transfer, spibus_transfer_impl),
>> +
>> + DEVMETHOD(spibus_sbe, spibus_sbe_impl),
>> + DEVMETHOD(spibus_sbpol, spibus_sbpol_impl),
>>
>> DEVMETHOD_END
>> };
>> --- dev/spibus/spibus_if.m.orig 2018-12-22 00:49:22.440211000
>> +0900
>> +++ dev/spibus/spibus_if.m 2018-12-30 23:58:00.000000000 +0900
>> @@ -39,3 +39,15 @@ METHOD int transfer {
>> device_t child;
>> struct spi_command *cmd;
>> };
>> +
>> +METHOD int sbe {
>> + device_t dev;
>> + device_t child;
>> + uint32_t *request;
>> +};
>> +
>> +METHOD int sbpol {
>> + device_t dev;
>> + device_t child;
>> + uint32_t *request;
>> +};
>> --- dev/spibus/spigen.c.orig 2018-12-29 20:19:20.584696000
>> +0900
>> +++ dev/spibus/spigen.c 2018-12-30 23:58:00.000000000 +0900
>> @@ -248,6 +248,28 @@ spigen_transfer_mmapped(struct cdev *cdev,
>> struct spig
>> }
>>
>> static int
>> +spigen_sbe(struct cdev *cdev, uint32_t *request)
>> +{
>> + device_t dev = cdev->si_drv1;
>> + int error = 0;
>> +
>> + error = SPIBUS_SBE(device_get_parent(dev), dev, (uint32_t
>> *)request);
>> +
>> + return (error);
>> +}
>> +
>> +static int
>> +spigen_sbpol(struct cdev *cdev, uint32_t *request)
>> +{
>> + device_t dev = cdev->si_drv1;
>> + int error = 0;
>> +
>> + error = SPIBUS_SBPOL(device_get_parent(dev), dev, (uint32_t
>> *)request);
>> +
>> + return (error);
>> +}
>> +
>> +static int
>> spigen_ioctl(struct cdev *cdev, u_long cmd, caddr_t data, int fflag,
>> struct thread *td)
>> {
>> @@ -272,6 +294,12 @@ spigen_ioctl(struct cdev *cdev, u_long cmd,
>> caddr_t da
>> break;
>> case SPIGENIOC_SET_SPI_MODE:
>> error = spibus_set_mode(dev, *(uint32_t *)data);
>> + break;
>> + case SPIGENIOC_SBE:
>> + error = spigen_sbe(cdev, (uint32_t *)data);
>> + break;
>> + case SPIGENIOC_SBPOL:
>> + error = spigen_sbpol(cdev, (uint32_t *)data);
>> break;
>> default:
>> error = ENOTTY;
>> --- sys/spigenio.h.orig 2018-12-22 00:48:50.752200000 +0900
>> +++ sys/spigenio.h 2018-12-30 23:58:00.000000000 +0900
>> @@ -52,5 +52,7 @@ struct spigen_transfer_mmapped {
>> #define SPIGENIOC_SET_CLOCK_SPEED _IOW(SPIGENIOC_BASE, 3, uint32_t)
>> #define SPIGENIOC_GET_SPI_MODE _IOR(SPIGENIOC_BASE, 4, uint32_t)
>> #define SPIGENIOC_SET_SPI_MODE _IOW(SPIGENIOC_BASE, 5, uint32_t)
>> +#define SPIGENIOC_SBE _IOW(SPIGENIOC_BASE, 6, uint32_t)
>> +#define SPIGENIOC_SBPOL _IOW(SPIGENIOC_BASE, 7, uint32_t)
>>
>> #endif /* !_SYS_SPIGENIO_H_ */
>>
>> --
>
> I've been working with SPI devices for years, and I don't think I've
> ever heard of this SBE and SBPOL stuff. Can you point me to a standards
> document or something else that describes it?
>
> -- Ian
Sure, here it is.
Fig. 9.3.1, p. 30, https://www.crystalfontz.com/controllers/Sitronix/ST7735/
When the start bit is enabled, one extra clock is added,
request = 1;
ioctl(lcd->spi_fd, SPIGENIOC_SBE, &request);
and the data porarity is controled by the start bit porarity.
ioctl(h->spi_fd, SPIGENIOC_SBPOL, &request);
By this patch, BeagleBone Mini Display Cape is usable.
https://www.logicsupply.com/999-0004100/
--
SAITOU Toshihide
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