serial/arc-uart: switch to devicetree based probing

* DT binding for arc-uart
* With alll the bits in place we can now use DT probing.

Note that there's a bit of kludge right now because earlyprintk portion
of driver can't use the DT infrastrcuture to get resoures/plat_data.
This requires some infrastructre changes to of_flat_ framework

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Rob Landley <rob@landley.net>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 66 insertions, 3 deletions

diff --git a/Documentation/devicetree/bindings/tty/serial/arc-uart.txt b/Documentation/devicetree/bindings/tty/serial/arc-uart.txt
new file mode 100644
index 000000000000..c3bd8f9c9997
--- /dev/null
+++ b/Documentation/devicetree/bindings/tty/serial/arc-uart.txt
@@ -0,0 +1,26 @@
+* Synopsys ARC UART : Non standard UART used in some of the ARC FPGA boards
+
+Required properties:
+- compatible            : "snps,arc-uart"
+- reg                   : offset and length of the register set for the device.
+- interrupts            : device interrupt
+- clock-frequency       : the input clock frequency for the UART
+- baud                  : baud rate for UART
+
+e.g.
+
+arcuart0: serial@c0fc1000 {
+        compatible = "snps,arc-uart";
+        reg = <0xc0fc1000 0x100>;
+        interrupts = <5>;
+        clock-frequency = <80000000>;
+        baud = <115200>;
+        status = "okay";
+};
+
+Note: Each port should have an alias correctly numbered in "aliases" node.
+
+e.g.
+aliases {
+        serial0 = &arcuart0;
+};
diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
index 2db64105677b..b46860104312 100644
--- a/drivers/tty/serial/arc_uart.c
+++ b/drivers/tty/serial/arc_uart.c
@@ -37,6 +37,8 @@
 #include <linux/tty_flip.h>
 #include <linux/serial_core.h>
 #include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
 
 /*************************************
  * ARC UART Hardware Specs
@@ -537,8 +539,26 @@ arc_uart_init_one(struct platform_device *pdev, int dev_id)
                 return -ENODEV;
 
         uart->is_emulated = !!plat_data[0];     /* workaround ISS bug */
-        uart->port.uartclk = plat_data[1];
-        uart->baud = plat_data[2];
+
+        if (is_early_platform_device(pdev)) {
+                uart->port.uartclk = plat_data[1];
+                uart->baud = plat_data[2];
+        } else {
+                struct device_node *np = pdev->dev.of_node;
+                u32 val;
+
+                if (of_property_read_u32(np, "clock-frequency", &val)) {
+                        dev_err(&pdev->dev, "clock-frequency property NOTset\n");
+                        return -EINVAL;
+                }
+                uart->port.uartclk = val;
+
+                if (of_property_read_u32(np, "baud", &val)) {
+                        dev_err(&pdev->dev, "baud property NOT set\n");
+                        return -EINVAL;
+                }
+                uart->baud = val;
+        }
 
         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         if (!res)
@@ -673,8 +693,18 @@ static int __init arc_serial_probe_earlyprintk(struct platform_device *pdev)
 static int arc_serial_probe(struct platform_device *pdev)
 {
         int rc, dev_id;
+        struct device_node *np = pdev->dev.of_node;
+
+        /* no device tree device */
+        if (!np)
+                return -ENODEV;
+
+        dev_id = of_alias_get_id(np, "serial");
+        if (dev_id < 0) {
+                dev_err(&pdev->dev, "failed to get alias id: %d\n", dev_id);
+                return dev_id;
+        }
 
-        dev_id = pdev->id < 0 ? 0 : pdev->id;
         rc = arc_uart_init_one(pdev, dev_id);
         if (rc)
                 return rc;
@@ -689,12 +719,19 @@ static int arc_serial_remove(struct platform_device *pdev)
         return 0;
 }
 
+static const struct of_device_id arc_uart_dt_ids[] = {
+        { .compatible = "snps,arc-uart" },
+        { /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, arc_uart_dt_ids);
+
 static struct platform_driver arc_platform_driver = {
         .probe = arc_serial_probe,
         .remove = arc_serial_remove,
         .driver = {
                 .name = DRIVER_NAME,
                 .owner = THIS_MODULE,
+                .of_match_table  = arc_uart_dt_ids,
          },
 };