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@@ -205,18 +205,30 @@ static void cdns_spi_chipselect(struct spi_device *spi, bool is_high)
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static void cdns_spi_config_clock_mode(struct spi_device *spi)
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{
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struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
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- u32 ctrl_reg;
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+ u32 ctrl_reg, new_ctrl_reg;
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- ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET);
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+ new_ctrl_reg = ctrl_reg = cdns_spi_read(xspi, CDNS_SPI_CR_OFFSET);
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/* Set the SPI clock phase and clock polarity */
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- ctrl_reg &= ~(CDNS_SPI_CR_CPHA_MASK | CDNS_SPI_CR_CPOL_MASK);
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+ new_ctrl_reg &= ~(CDNS_SPI_CR_CPHA_MASK | CDNS_SPI_CR_CPOL_MASK);
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if (spi->mode & SPI_CPHA)
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- ctrl_reg |= CDNS_SPI_CR_CPHA_MASK;
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+ new_ctrl_reg |= CDNS_SPI_CR_CPHA_MASK;
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if (spi->mode & SPI_CPOL)
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- ctrl_reg |= CDNS_SPI_CR_CPOL_MASK;
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-
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- cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, ctrl_reg);
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+ new_ctrl_reg |= CDNS_SPI_CR_CPOL_MASK;
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+
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+ if (new_ctrl_reg != ctrl_reg) {
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+ /*
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+ * Just writing the CR register does not seem to apply the clock
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+ * setting changes. This is problematic when changing the clock
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+ * polarity as it will cause the SPI slave to see spurious clock
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+ * transitions. To workaround the issue toggle the ER register.
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+ */
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+ cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
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+ CDNS_SPI_ER_DISABLE_MASK);
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+ cdns_spi_write(xspi, CDNS_SPI_CR_OFFSET, new_ctrl_reg);
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+ cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
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+ CDNS_SPI_ER_ENABLE_MASK);
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+ }
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}
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/**
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@@ -370,6 +382,12 @@ static irqreturn_t cdns_spi_irq(int irq, void *dev_id)
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return status;
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}
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+static int cdns_prepare_message(struct spi_master *master,
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+ struct spi_message *msg)
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+{
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+ cdns_spi_config_clock_mode(msg->spi);
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+ return 0;
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+}
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/**
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* cdns_transfer_one - Initiates the SPI transfer
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@@ -416,8 +434,6 @@ static int cdns_prepare_transfer_hardware(struct spi_master *master)
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{
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struct cdns_spi *xspi = spi_master_get_devdata(master);
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- cdns_spi_config_clock_mode(master->cur_msg->spi);
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-
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cdns_spi_write(xspi, CDNS_SPI_ER_OFFSET,
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CDNS_SPI_ER_ENABLE_MASK);
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@@ -532,6 +548,7 @@ static int cdns_spi_probe(struct platform_device *pdev)
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xspi->is_decoded_cs = 0;
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master->prepare_transfer_hardware = cdns_prepare_transfer_hardware;
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+ master->prepare_message = cdns_prepare_message;
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master->transfer_one = cdns_transfer_one;
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master->unprepare_transfer_hardware = cdns_unprepare_transfer_hardware;
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master->set_cs = cdns_spi_chipselect;
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