msm_serial: Add devicetree support

Add devicetree support to the msm_serial driver. Clocks are still
queried by direct name from the driver until device tree clock support
is implemented.

Change-Id: Ia6b2ddfcf1e5dc3bd25dd502662f971202e6d56f
Signed-off-by: David Brown <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>

Documentation/devicetree/bindings/tty/serial/msm_serial.txt

···
+* Qualcomm MSM UART
+
+Required properties:
+- compatible :
+	- "qcom,msm-uart", and one of "qcom,msm-hsuart" or
+	  "qcom,msm-lsuart".
+- reg : offset and length of the register set for the device
+	for the hsuart operating in compatible mode, there should be a
+	second pair describing the gsbi registers.
+- interrupts : should contain the uart interrupt.
+
+There are two different UART blocks used in MSM devices,
+"qcom,msm-hsuart" and "qcom,msm-lsuart".  The msm-serial driver is
+able to handle both of these, and matches against the "qcom,msm-uart"
+as the compatibility.
+
+The registers for the "qcom,msm-hsuart" device need to specify both
+register blocks, even for the common driver.
+
+Example:
+
+	uart@19c400000 {
+		compatible = "qcom,msm-hsuart", "qcom,msm-uart";
+		reg = <0x19c40000 0x1000>,
+		      <0x19c00000 0x1000>;
+		interrupts = <195>;
+	};

drivers/tty/serial/msm_serial.c

···
 # define SUPPORT_SYSRQ
 #endif
 
+#include <linux/atomic.h>
 #include <linux/hrtimer.h>
 #include <linux/module.h>
 #include <linux/io.h>
···
 #include <linux/clk.h>
 #include <linux/platform_device.h>
 #include <linux/delay.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 
 #include "msm_serial.h"
 
···
 	.cons = MSM_CONSOLE,
 };
 
+static atomic_t msm_uart_next_id = ATOMIC_INIT(0);
+
 static int __init msm_serial_probe(struct platform_device *pdev)
 {
 	struct msm_port *msm_port;
 	struct resource *resource;
 	struct uart_port *port;
 	int irq;
+
+	if (pdev->id == -1)
+		pdev->id = atomic_inc_return(&msm_uart_next_id) - 1;
 
 	if (unlikely(pdev->id < 0 || pdev->id >= UART_NR))
 		return -ENXIO;
···
 	return 0;
 }
 
+static struct of_device_id msm_match_table[] = {
+	{ .compatible = "qcom,msm-uart" },
+	{}
+};
+
 static struct platform_driver msm_platform_driver = {
 	.remove = msm_serial_remove,
 	.driver = {
 		.name = "msm_serial",
 		.owner = THIS_MODULE,
+		.of_match_table = msm_match_table,
 	},
 };