tty: ar933x_uart: add device tree support and binding documentation

Modify the probe routine to get the port line number
from device tree if the 'of_node' is populated in the
platform device. The driver can be built as module,
thus add an OF specific module device table as well
to support module auto loading.

This makes it possible to use the driver for AR9330
UART devices specified in device tree.

Cc: devicetree@vger.kernel.org
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 25 insertions, 3 deletions

diff --git a/drivers/tty/serial/ar933x_uart.c b/drivers/tty/serial/ar933x_uart.c
index 0437a9e08d58..acd03af7cd52 100644
--- a/drivers/tty/serial/ar933x_uart.c
+++ b/drivers/tty/serial/ar933x_uart.c
@@ -17,6 +17,8 @@
 #include <linux/sysrq.h>
 #include <linux/delay.h>
 #include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
 #include <linux/serial_core.h>
@@ -623,13 +625,24 @@ static int ar933x_uart_probe(struct platform_device *pdev)
         struct uart_port *port;
         struct resource *mem_res;
         struct resource *irq_res;
+        struct device_node *np;
         unsigned int baud;
         int id;
         int ret;
 
-        id = pdev->id;
-        if (id == -1)
-                id = 0;
+        np = pdev->dev.of_node;
+        if (config_enabled(CONFIG_OF) && np) {
+                id = of_alias_get_id(np, "serial");
+                if (id < 0) {
+                        dev_err(&pdev->dev, "unable to get alias id, err=%d\n",
+                                id);
+                        return id;
+                }
+        } else {
+                id = pdev->id;
+                if (id == -1)
+                        id = 0;
+        }
 
         if (id > CONFIG_SERIAL_AR933X_NR_UARTS)
                 return -EINVAL;
@@ -713,12 +726,21 @@ static int ar933x_uart_remove(struct platform_device *pdev)
         return 0;
 }
 
+#ifdef CONFIG_OF
+static const struct of_device_id ar933x_uart_of_ids[] = {
+        { .compatible = "qca,ar9330-uart" },
+        {},
+};
+MODULE_DEVICE_TABLE(of, ar933x_uart_of_ids);
+#endif
+
 static struct platform_driver ar933x_uart_platform_driver = {
         .probe          = ar933x_uart_probe,
         .remove         = ar933x_uart_remove,
         .driver         = {
                 .name           = DRIVER_NAME,
                 .owner          = THIS_MODULE,
+                .of_match_table = of_match_ptr(ar933x_uart_of_ids),
         },
 };