rtc/spear: add Device Tree probing capability

SPEAr platforms now support DT and so must convert all drivers support DT.
This patch adds DT probing support for rtc and updates its documentation
too.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Rajeev Kumar <rajeev-dlh.kumar@st.com>
Cc: Rob Herring <robherring2@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/rtc-spear.c b/drivers/rtc/rtc-spear.c
index e38da0d..1f76320 100644
--- a/drivers/rtc/rtc-spear.c
+++ b/drivers/rtc/rtc-spear.c
@@ -16,6 +16,7 @@
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>
 #include <linux/slab.h>
@@ -519,6 +520,14 @@
 	clk_disable(config->clk);
 }
 
+#ifdef CONFIG_OF
+static const struct of_device_id spear_rtc_id_table[] = {
+	{ .compatible = "st,spear600-rtc" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, spear_rtc_id_table);
+#endif
+
 static struct platform_driver spear_rtc_driver = {
 	.probe = spear_rtc_probe,
 	.remove = __devexit_p(spear_rtc_remove),
@@ -527,6 +536,7 @@
 	.shutdown = spear_rtc_shutdown,
 	.driver = {
 		.name = "rtc-spear",
+		.of_match_table = of_match_ptr(spear_rtc_id_table),
 	},
 };