Merge remote-tracking branches 'spi/topic/adi-v3', 'spi/topic/atmel', 'spi/topic...

[firefly-linux-kernel-4.4.55.git] / drivers / spi / spi-cadence.c

diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c
index 98b763b705d7782da331e227de1ab6068595b562..562ff83debd9f4a7c8c5ac5e9bd0156d73a3581f 100644 (file)
--- 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;