omap-serial: Add minimal device tree support

Adapt the driver to device tree and pass minimal platform
data from device tree needed for console boot.
No power management features will be suppported for now
since it requires more tweaks around OCP settings
to toggle forceidle/noidle/smartidle bits and handling
remote wakeup and dynamic muxing.

Signed-off-by: Rajendra Nayak <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Tony Lindgren <[e-mail]>

Documentation/devicetree/bindings/serial/omap_serial.txt

···
+OMAP UART controller
+
+Required properties:
+- compatible : should be "ti,omap2-uart" for OMAP2 controllers
+- compatible : should be "ti,omap3-uart" for OMAP3 controllers
+- compatible : should be "ti,omap4-uart" for OMAP4 controllers
+- ti,hwmods : Must be "uart<n>", n being the instance number (1-based)
+
+Optional properties:
+- clock-frequency : frequency of the clock input to the UART

drivers/tty/serial/omap-serial.c

···
 #include <linux/serial_core.h>
 #include <linux/irq.h>
 #include <linux/pm_runtime.h>
+#include <linux/of.h>
 
 #include <plat/dma.h>
 #include <plat/dmtimer.h>
···
 	return;
 }
 
+static struct omap_uart_port_info *of_get_uart_port_info(struct device *dev)
+{
+	struct omap_uart_port_info *omap_up_info;
+
+	omap_up_info = devm_kzalloc(dev, sizeof(*omap_up_info), GFP_KERNEL);
+	if (!omap_up_info)
+		return NULL; /* out of memory */
+
+	of_property_read_u32(dev->of_node, "clock-frequency",
+					 &omap_up_info->uartclk);
+	return omap_up_info;
+}
+
 static int serial_omap_probe(struct platform_device *pdev)
 {
 	struct uart_omap_port	*up;
 	struct resource		*mem, *irq, *dma_tx, *dma_rx;
 	struct omap_uart_port_info *omap_up_info = pdev->dev.platform_data;
 	int ret = -ENOSPC;
+
+	if (pdev->dev.of_node)
+		omap_up_info = of_get_uart_port_info(&pdev->dev);
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!mem) {
···
 	up->port.regshift = 2;
 	up->port.fifosize = 64;
 	up->port.ops = &serial_omap_pops;
-	up->port.line = pdev->id;
-	sprintf(up->name, "OMAP UART%d", up->port.line);
 
+	if (pdev->dev.of_node)
+		up->port.line = of_alias_get_id(pdev->dev.of_node, "serial");
+	else
+		up->port.line = pdev->id;
+
+	if (up->port.line < 0) {
+		dev_err(&pdev->dev, "failed to get alias/pdev id, errno %d\n",
+								up->port.line);
+		ret = -ENODEV;
+		goto err;
+	}
+
+	sprintf(up->name, "OMAP UART%d", up->port.line);
 	up->port.mapbase = mem->start;
 	up->port.membase = ioremap(mem->start, resource_size(mem));
 	if (!up->port.membase) {
···
 	if (!up)
 		return -EINVAL;
 
-	if (!pdata->enable_wakeup)
+	if (!pdata || !pdata->enable_wakeup)
 		return 0;
 
 	if (pdata->get_context_loss_count)
···
 				serial_omap_runtime_resume, NULL)
 };
 
+#if defined(CONFIG_OF)
+static const struct of_device_id omap_serial_of_match[] = {
+	{ .compatible = "ti,omap2-uart" },
+	{ .compatible = "ti,omap3-uart" },
+	{ .compatible = "ti,omap4-uart" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, omap_serial_of_match);
+#endif
+
 static struct platform_driver serial_omap_driver = {
 	.probe          = serial_omap_probe,
 	.remove         = serial_omap_remove,
 	.driver		= {
 		.name	= DRIVER_NAME,
 		.pm	= &serial_omap_dev_pm_ops,
+		.of_match_table = of_match_ptr(omap_serial_of_match),
 	},
 };