[PATCH V4 4/4] clocksource: mips-gic: Add device-tree support

[Andrew Bresticker <abrestic@chromium.org>]

Parse the GIC timer frequency and interrupt from the device-tree.
Since the GIC timer requires the GIC irqchip to have been set up
already and is a sub-node of the GIC, probe the GIC timer from the
GIC irqchip.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
Changes from v3:
 - probe from GIC irqchip
New for v3.
---
 drivers/clocksource/Kconfig          |  1 +
 drivers/clocksource/mips-gic-timer.c | 35 ++++++++++++++++++++++++++++-------
 drivers/irqchip/irq-mips-gic.c       |  7 +++++++
 include/linux/irqchip/mips-gic.h     |  3 +++
 4 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index cb7e7f4..89836dc 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -226,5 +226,6 @@ config CLKSRC_VERSATILE
 config CLKSRC_MIPS_GIC
 	bool
 	depends on MIPS_GIC
+	select CLKSRC_OF
 
 endmenu
diff --git a/drivers/clocksource/mips-gic-timer.c b/drivers/clocksource/mips-gic-timer.c
index a749c81..b59f04b 100644
--- a/drivers/clocksource/mips-gic-timer.c
+++ b/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 +122,39 @@ 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();
+}
+
+void __init gic_clocksource_of_init(struct device_node *node)
+{
+	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();
+}
diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index 8a9ef74..3145e87 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -742,6 +742,7 @@ void __init gic_init(unsigned long gic_base_addr,
 static int __init gic_of_init(struct device_node *node,
 			      struct device_node *parent)
 {
+	struct device_node *child;
 	struct resource res;
 	unsigned int cpu_vec, i = 0, reserved = 0;
 	phys_addr_t gic_base;
@@ -784,6 +785,12 @@ static int __init gic_of_init(struct device_node *node,
 
 	__gic_init(gic_base, gic_len, cpu_vec, 0, node);
 
+	/* Set up the GIC timer, if present. */
+	for_each_child_of_node(node, child) {
+		if (of_device_is_compatible(child, "mti,gic-timer"))
+			gic_clocksource_of_init(child);
+	}
+
 	return 0;
 }
 IRQCHIP_DECLARE(mips_gic, "mti,gic", gic_of_init);
diff --git a/include/linux/irqchip/mips-gic.h b/include/linux/irqchip/mips-gic.h
index 420f77b..7b383b2 100644
--- a/include/linux/irqchip/mips-gic.h
+++ b/include/linux/irqchip/mips-gic.h
@@ -229,12 +229,15 @@
 #define GIC_SHARED_TO_HWIRQ(x)	(GIC_SHARED_HWIRQ_BASE + (x))
 #define GIC_HWIRQ_TO_SHARED(x)	((x) - GIC_SHARED_HWIRQ_BASE)
 
+struct device_node;
+
 extern unsigned int gic_present;
 
 extern void gic_init(unsigned long gic_base_addr,
 	unsigned long gic_addrspace_size, unsigned int cpu_vec,
 	unsigned int irqbase);
 extern void gic_clocksource_init(unsigned int);
+extern void gic_clocksource_of_init(struct device_node *node);
 extern cycle_t gic_read_count(void);
 extern unsigned int gic_get_count_width(void);
 extern cycle_t gic_read_compare(void);
-- 
2.1.0.rc2.206.gedb03e5