clocksource: mips-gic: Add device-tree support

Parse the GIC timer frequency and interrupt from the device-tree.
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: John Crispin <blogic@openwrt.org>
Cc: David Daney <ddaney.cavm@gmail.com>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8421/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

drivers/clocksource/Kconfig

@@ -226,5 +226,6 @@ config CLKSRC_VERSATILE
 config CLKSRC_MIPS_GIC
 	bool
 	depends on MIPS_GIC
+	select CLKSRC_OF
 
 endmenu

drivers/clocksource/mips-gic-timer.c

@@ -11,6 +11,7 @@
 #include <linux/interrupt.h>
 #include <linux/irqchip/mips-gic.h>
 #include <linux/notifier.h>
+#include <linux/of_irq.h>
 #include <linux/percpu.h>
 #include <linux/smp.h>
 #include <linux/time.h>
@@ -101,8 +102,6 @@ static int gic_clockevent_init(void)
 	if (!cpu_has_counter || !gic_frequency)
 		return -ENXIO;
 
-	gic_timer_irq = MIPS_GIC_IRQ_BASE +
-		GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
 	setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
 
 	register_cpu_notifier(&gic_cpu_nb);
@@ -123,17 +122,45 @@ static struct clocksource gic_clocksource = {
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
-void __init gic_clocksource_init(unsigned int frequency)
+static void __init __gic_clocksource_init(void)
 {
-	gic_frequency = frequency;
-
 	/* Set clocksource mask. */
 	gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width());
 
 	/* Calculate a somewhat reasonable rating value. */
-	gic_clocksource.rating = 200 + frequency / 10000000;
+	gic_clocksource.rating = 200 + gic_frequency / 10000000;
 
-	clocksource_register_hz(&gic_clocksource, frequency);
+	clocksource_register_hz(&gic_clocksource, gic_frequency);
 
 	gic_clockevent_init();
 }
+
+void __init gic_clocksource_init(unsigned int frequency)
+{
+	gic_frequency = frequency;
+	gic_timer_irq = MIPS_GIC_IRQ_BASE +
+		GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
+
+	__gic_clocksource_init();
+}
+
+static void __init gic_clocksource_of_init(struct device_node *node)
+{
+	if (WARN_ON(!gic_present || !node->parent ||
+		    !of_device_is_compatible(node->parent, "mti,gic")))
+		return;
+
+	if (of_property_read_u32(node, "clock-frequency", &gic_frequency)) {
+		pr_err("GIC frequency not specified.\n");
+		return;
+	}
+	gic_timer_irq = irq_of_parse_and_map(node, 0);
+	if (!gic_timer_irq) {
+		pr_err("GIC timer IRQ not specified.\n");
+		return;
+	}
+
+	__gic_clocksource_init();
+}
+CLOCKSOURCE_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
+		       gic_clocksource_of_init);