diff options
Diffstat (limited to 'drivers/spi/spi-cadence.c')
| -rw-r--r-- | drivers/spi/spi-cadence.c | 37 |
1 files changed, 27 insertions, 10 deletions
diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c index bb75897..562ff83 100644 --- a/drivers/spi/spi-cadence.c +++ b/drivers/spi/spi-cadence.c @@ -205,18 +205,30 @@ static void cdns_spi_chipselect(struct spi_device *spi, bool is_high) static void cdns_spi_config_clock_mode(struct spi_device *spi) { struct cdns_spi *xspi = spi_master_get_devdata(spi->master); - u32 ctrl_reg; + u32 ctrl_reg, new_ctrl_reg; - ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET); + new_ctrl_reg = ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET); /* Set the SPI clock phase and clock polarity */ - ctrl_reg &= ~(CDNS_SPI_CR_CPHA_MASK | CDNS_SPI_CR_CPOL_MASK); + new_ctrl_reg &= ~(CDNS_SPI_CR_CPHA_MASK | CDNS_SPI_CR_CPOL_MASK); if (spi->mode & SPI_CPHA) - ctrl_reg |= CDNS_SPI_CR_CPHA_MASK; + new_ctrl_reg |= CDNS_SPI_CR_CPHA_MASK; if (spi->mode & SPI_CPOL) - ctrl_reg |= CDNS_SPI_CR_CPOL_MASK; - - cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, ctrl_reg); + new_ctrl_reg |= CDNS_SPI_CR_CPOL_MASK; + + if (new_ctrl_reg != ctrl_reg) { + /* + * Just writing the CR register does not seem to apply the clock + * setting changes. This is problematic when changing the clock + * polarity as it will cause the SPI slave to see spurious clock + * transitions. To workaround the issue toggle the ER register. + */ + cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, + CDNS_SPI_ER_DISABLE_MASK); + cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, new_ctrl_reg); + cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, + CDNS_SPI_ER_ENABLE_MASK); + } } /** @@ -370,6 +382,12 @@ static irqreturn_t cdns_spi_irq(int irq, void *dev_id) return status; } +static int cdns_prepare_message(struct spi_master *master, + struct spi_message *msg) +{ + cdns_spi_config_clock_mode(msg->spi); + return 0; +} /** * cdns_transfer_one - Initiates the SPI transfer @@ -416,8 +434,6 @@ static int cdns_prepare_transfer_hardware(struct spi_master *master) { struct cdns_spi *xspi = spi_master_get_devdata(master); - cdns_spi_config_clock_mode(master->cur_msg->spi); - cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET, CDNS_SPI_ER_ENABLE_MASK); @@ -532,6 +548,7 @@ static int cdns_spi_probe(struct platform_device *pdev) xspi->is_decoded_cs = 0; master->prepare_transfer_hardware = cdns_prepare_transfer_hardware; + master->prepare_message = cdns_prepare_message; master->transfer_one = cdns_transfer_one; master->unprepare_transfer_hardware = cdns_unprepare_transfer_hardware; master->set_cs = cdns_spi_chipselect; @@ -647,7 +664,7 @@ static int __maybe_unused cdns_spi_resume(struct device *dev) static SIMPLE_DEV_PM_OPS(cdns_spi_dev_pm_ops, cdns_spi_suspend, cdns_spi_resume); -static struct of_device_id cdns_spi_of_match[] = { +static const struct of_device_id cdns_spi_of_match[] = { { .compatible = "xlnx,zynq-spi-r1p6" }, { .compatible = "cdns,spi-r1p6" }, { /* end of table */ } |
