ARM: architected timers: add DT support

Add runtime DT support and documentation for the Cortex A7/A15
architected timers.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

2 files changed, 52 insertions, 7 deletions

diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index dc008c696b5a..935897f120b6 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -10,12 +10,18 @@ struct arch_timer {
 #ifdef CONFIG_ARM_ARCH_TIMER
 int arch_timer_register(struct arch_timer *);
 int arch_timer_sched_clock_init(void);
+int arch_timer_of_register(void);
 #else
 static inline int arch_timer_register(struct arch_timer *at)
 {
         return -ENXIO;
 }
 
+static inline int arch_timer_of_register(void)
+{
+        return -ENXIO;
+}
+
 static inline int arch_timer_sched_clock_init(void)
 {
         return -ENXIO;
diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index dd907048f571..1a34eeebc26e 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -17,6 +17,7 @@
 #include <linux/jiffies.h>
 #include <linux/clockchips.h>
 #include <linux/interrupt.h>
+#include <linux/of_irq.h>
 #include <linux/io.h>
 
 #include <asm/cputype.h>
@@ -245,13 +246,10 @@ static struct local_timer_ops arch_timer_ops __cpuinitdata = {
         .stop   = arch_timer_stop,
 };
 
-int __init arch_timer_register(struct arch_timer *at)
+static int __init arch_timer_common_register(void)
 {
         int err;
 
-        if (at->res[0].start <= 0 || !(at->res[0].flags & IORESOURCE_IRQ))
-                return -EINVAL;
-
         err = arch_timer_available();
         if (err)
                 return err;
@@ -262,7 +260,6 @@ int __init arch_timer_register(struct arch_timer *at)
 
         clocksource_register_hz(&clocksource_counter, arch_timer_rate);
 
-        arch_timer_ppi = at->res[0].start;
         err = request_percpu_irq(arch_timer_ppi, arch_timer_handler,
                                  "arch_timer", arch_timer_evt);
         if (err) {
@@ -271,8 +268,7 @@ int __init arch_timer_register(struct arch_timer *at)
                 goto out_free;
         }
 
-        if (at->res[1].start > 0 || (at->res[1].flags & IORESOURCE_IRQ)) {
-                arch_timer_ppi2 = at->res[1].start;
+        if (arch_timer_ppi2) {
                 err = request_percpu_irq(arch_timer_ppi2, arch_timer_handler,
                                          "arch_timer", arch_timer_evt);
                 if (err) {
@@ -300,6 +296,49 @@ out_free:
         return err;
 }
 
+int __init arch_timer_register(struct arch_timer *at)
+{
+        if (at->res[0].start <= 0 || !(at->res[0].flags & IORESOURCE_IRQ))
+                return -EINVAL;
+
+        arch_timer_ppi = at->res[0].start;
+
+        if (at->res[1].start > 0 || (at->res[1].flags & IORESOURCE_IRQ))
+                arch_timer_ppi2 = at->res[1].start;
+
+        return arch_timer_common_register();
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id arch_timer_of_match[] __initconst = {
+        { .compatible   = "arm,armv7-timer",    },
+        {},
+};
+
+int __init arch_timer_of_register(void)
+{
+        struct device_node *np;
+        u32 freq;
+
+        np = of_find_matching_node(NULL, arch_timer_of_match);
+        if (!np) {
+                pr_err("arch_timer: can't find DT node\n");
+                return -ENODEV;
+        }
+
+        /* Try to determine the frequency from the device tree or CNTFRQ */
+        if (!of_property_read_u32(np, "clock-frequency", &freq))
+                arch_timer_rate = freq;
+
+        arch_timer_ppi = irq_of_parse_and_map(np, 0);
+        arch_timer_ppi2 = irq_of_parse_and_map(np, 1);
+        pr_info("arch_timer: found %s irqs %d %d\n",
+                np->name, arch_timer_ppi, arch_timer_ppi2);
+
+        return arch_timer_common_register();
+}
+#endif
+
 int __init arch_timer_sched_clock_init(void)
 {
         int err;