2 files changed, 46 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
new file mode 100644
index 000000000000..bd99193e87b9
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
@@ -0,0 +1,28 @@
+Synopsys DesignWare AMBA 2.0 Synchronous Serial Interface.
+
+Required properties:
+- compatible : "snps,dw-apb-ssi"
+- reg : The register base for the controller.
+- interrupts : One interrupt, used by the controller.
+- #address-cells : <1>, as required by generic SPI binding.
+- #size-cells : <0>, also as required by generic SPI binding.
+
+Optional properties:
+- cs-gpios : Specifies the gpio pis to be used for chipselects.
+- num-cs : The number of chipselects. If omitted, this will default to 4.
+
+Child nodes as per the generic SPI binding.
+
+Example:
+
+        spi@fff00000 {
+                compatible = "snps,dw-apb-ssi";
+                reg = <0xfff00000 0x1000>;
+                interrupts = <0 154 4>;
+                #address-cells = <1>;
+                #size-cells = <0>;
+                num-cs = <2>;
+                cs-gpios = <&gpio0 13 0>,
+                           <&gpio0 14 0>;
+        };
+
diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index a5cba14ac3d2..21ce0e36fa00 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -16,7 +16,9 @@
 #include <linux/spi/spi.h>
 #include <linux/scatterlist.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/of_gpio.h>
+#include <linux/of_platform.h>
 
 #include "spi-dw.h"
 
@@ -33,6 +35,7 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
         struct dw_spi *dws;
         struct resource *mem;
         int ret;
+        int num_cs;
 
         dwsmmio = devm_kzalloc(&pdev->dev, sizeof(struct dw_spi_mmio),
                         GFP_KERNEL);
@@ -68,9 +71,16 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
                 return ret;
 
         dws->bus_num = pdev->id;
-        dws->num_cs = 4;
+
         dws->max_freq = clk_get_rate(dwsmmio->clk);
 
+        num_cs = 4;
+
+        if (pdev->dev.of_node)
+                of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs);
+
+        dws->num_cs = num_cs;
+
         if (pdev->dev.of_node) {
                 int i;
 
@@ -114,12 +124,19 @@ static int dw_spi_mmio_remove(struct platform_device *pdev)
         return 0;
 }
 
+static const struct of_device_id dw_spi_mmio_of_match[] = {
+        { .compatible = "snps,dw-apb-ssi", },
+        { /* end of table */}
+};
+MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);
+
 static struct platform_driver dw_spi_mmio_driver = {
         .probe          = dw_spi_mmio_probe,
         .remove         = dw_spi_mmio_remove,
         .driver         = {
                 .name   = DRIVER_NAME,
                 .owner  = THIS_MODULE,
+                .of_match_table = dw_spi_mmio_of_match,
         },
 };
 module_platform_driver(dw_spi_mmio_driver);