dw: spi: add support for Amazon's Alpine spi controller

Add support for a new devicetree compatible string called
'amazon,alpine-apb-ssi', which is necessary for the Amazon Alpine spi
controller. 'amazon,alpine-dw-apb-ssi' is used in the dw spi driver if
specified in the devicetree.  Otherwise, fall back to driver default
behavior, i.e. original dw IP hw driver behavior.

Signed-off-by: Talel Shenhar <talel@amazon.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 3e205ab60cd4..b705f2bdb8b9 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -144,6 +144,8 @@ void dw_spi_set_cs(struct spi_device *spi, bool enable)
 
         if (!enable)
                 dw_writel(dws, DW_SPI_SER, BIT(spi->chip_select));
+        else if (dws->cs_override)
+                dw_writel(dws, DW_SPI_SER, 0);
 }
 EXPORT_SYMBOL_GPL(dw_spi_set_cs);
 
@@ -463,6 +465,10 @@ static void spi_hw_init(struct device *dev, struct dw_spi *dws)
                 dws->fifo_len = (fifo == 1) ? 0 : fifo;
                 dev_dbg(dev, "Detected FIFO size: %u bytes\n", dws->fifo_len);
         }
+
+        /* enable HW fixup for explicit CS deselect for Amazon's alpine chip */
+        if (dws->cs_override)
+                dw_writel(dws, DW_SPI_CS_OVERRIDE, 0xF);
 }
 
 int dw_spi_add_host(struct device *dev, struct dw_spi *dws)