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path: root/drivers/spi/spi-cadence.c
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Diffstat (limited to 'drivers/spi/spi-cadence.c')
-rw-r--r--drivers/spi/spi-cadence.c37
1 files changed, 27 insertions, 10 deletions
diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c
index bb758978465d..562ff83debd9 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 */ }