spi/atmel: add DT support

Use the newly introduce cs-gpios dt support on atmel.
We do not use the hardware cs as it's wired and has bugs and limitations.
As the controller believes that only active-low devices/systems exists.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

2 files changed, 42 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/spi/spi_atmel.txt b/Documentation/devicetree/bindings/spi/spi_atmel.txt
new file mode 100644
index 000000000000..07e04cdc0c9e
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi_atmel.txt
@@ -0,0 +1,26 @@
+Atmel SPI device
+
+Required properties:
+- compatible : should be "atmel,at91rm9200-spi".
+- reg: Address and length of the register set for the device
+- interrupts: Should contain spi interrupt
+- cs-gpios: chipselects
+
+Example:
+
+spi1: spi@fffcc000 {
+        compatible = "atmel,at91rm9200-spi";
+        reg = <0xfffcc000 0x4000>;
+        interrupts = <13 4 5>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+        cs-gpios = <&pioB 3 0>;
+        status = "okay";
+
+        mmc-slot@0 {
+                compatible = "mmc-spi-slot";
+                reg = <0>;
+                gpios = <&pioC 4 0>;    /* CD */
+                spi-max-frequency = <25000000>;
+        };
+};
diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 75c0c4f5fdf2..ab34497bcfee 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -20,6 +20,7 @@
 #include <linux/spi/spi.h>
 #include <linux/slab.h>
 #include <linux/platform_data/atmel.h>
+#include <linux/of.h>
 
 #include <asm/io.h>
 #include <asm/gpio.h>
@@ -768,6 +769,10 @@ static int atmel_spi_setup(struct spi_device *spi)
 
         /* chipselect must have been muxed as GPIO (e.g. in board setup) */
         npcs_pin = (unsigned int)spi->controller_data;
+
+        if (gpio_is_valid(spi->cs_gpio))
+                npcs_pin = spi->cs_gpio;
+
         asd = spi->controller_state;
         if (!asd) {
                 asd = kzalloc(sizeof(struct atmel_spi_device), GFP_KERNEL);
@@ -937,8 +942,9 @@ static int atmel_spi_probe(struct platform_device *pdev)
         /* the spi->mode bits understood by this driver: */
         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 
+        master->dev.of_node = pdev->dev.of_node;
         master->bus_num = pdev->id;
-        master->num_chipselect = 4;
+        master->num_chipselect = master->dev.of_node ? 0 : 4;
         master->setup = atmel_spi_setup;
         master->transfer = atmel_spi_transfer;
         master->cleanup = atmel_spi_cleanup;
@@ -1064,11 +1070,20 @@ static int atmel_spi_resume(struct platform_device *pdev)
 #define atmel_spi_resume        NULL
 #endif
 
+#if defined(CONFIG_OF)
+static const struct of_device_id atmel_spi_dt_ids[] = {
+        { .compatible = "atmel,at91rm9200-spi" },
+        { /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, atmel_spi_dt_ids);
+#endif
 
 static struct platform_driver atmel_spi_driver = {
         .driver         = {
                 .name   = "atmel_spi",
                 .owner  = THIS_MODULE,
+                .of_match_table = of_match_ptr(atmel_spi_dt_ids),
         },
         .suspend        = atmel_spi_suspend,
         .resume         = atmel_spi_resume,