The Intel Mount Evans SoC's Integrated Management Complex uses the SPI
controller for access to a NOR SPI FLASH. However, the SoC doesn't
provide a mechanism to override the native chip select signal.
This driver doesn't use DMA for memory operations when a chip select
override is not provided due to the native chip select timing behavior.
As a result no DMA configuration is done for the controller and this
configuration is not tested.
The controller also has an errata where a full TX FIFO can result in
data corruption. The suggested workaround is to never completely fill
the FIFO. The TX FIFO has a size of 32 so the fifo_len is set to 31.
Signed-off-by: Abe Kohandel <abe.kohandel@xxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
drivers/spi/spi-dw-mmio.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index 5f2aee69c1c1..c1d16157de61 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -236,6 +236,31 @@ static int dw_spi_intel_init(struct platform_device *pdev,
return 0;
}
+/*
+ * The Intel Mount Evans SoC's Integrated Management Complex uses the
+ * SPI controller for access to a NOR SPI FLASH. However, the SoC doesn't
+ * provide a mechanism to override the native chip select signal.
+ *
+ * This driver doesn't use DMA for memory operations when a chip select
+ * override is not provided due to the native chip select timing behavior.
+ * As a result no DMA configuration is done for the controller and this
+ * configuration is not tested.
+ */
+static int dw_spi_mountevans_imc_init(struct platform_device *pdev,
+ struct dw_spi_mmio *dwsmmio)
+{
+ /*
+ * The Intel Mount Evans SoC's Integrated Management Complex DW
+ * apb_ssi_v4.02a controller has an errata where a full TX FIFO can
+ * result in data corruption. The suggested workaround is to never
+ * completely fill the FIFO. The TX FIFO has a size of 32 so the
+ * fifo_len is set to 31.
+ */
+ dwsmmio->dws.fifo_len = 31;
+
+ return 0;
+}
+
static int dw_spi_canaan_k210_init(struct platform_device *pdev,
struct dw_spi_mmio *dwsmmio)
{
@@ -405,6 +430,10 @@ static const struct of_device_id dw_spi_mmio_of_match[] = {
{ .compatible = "snps,dwc-ssi-1.01a", .data = dw_spi_hssi_init},
{ .compatible = "intel,keembay-ssi", .data = dw_spi_intel_init},
{ .compatible = "intel,thunderbay-ssi", .data = dw_spi_intel_init},
+ {
+ .compatible = "intel,mountevans-imc-ssi",
+ .data = dw_spi_mountevans_imc_init,
+ },
{ .compatible = "microchip,sparx5-spi", dw_spi_mscc_sparx5_init},
{ .compatible = "canaan,k210-spi", dw_spi_canaan_k210_init},
{ .compatible = "amd,pensando-elba-spi", .data = dw_spi_elba_init},
--
2.40.1
