ARM: smp_twd: add device tree support

Add bindings to support DT discovery of the ARM Timer Watchdog
(aka TWD). Only the timer side is converted by this patch.

Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

2 files changed, 72 insertions, 13 deletions

diff --git a/arch/arm/include/asm/smp_twd.h b/arch/arm/include/asm/smp_twd.h
index 16c89b793f9..8047e6e580b 100644
--- a/arch/arm/include/asm/smp_twd.h
+++ b/arch/arm/include/asm/smp_twd.h
@@ -40,4 +40,12 @@ struct twd_local_timer name __initdata = {	\
 
 int twd_local_timer_register(struct twd_local_timer *);
 
+#ifdef CONFIG_HAVE_ARM_TWD
+void twd_local_timer_of_register(void);
+#else
+static inline void twd_local_timer_of_register(void)
+{
+}
+#endif
+
 #endif
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index 18c55f1e4e4..761826c628b 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -20,6 +20,8 @@
 #include <linux/clockchips.h>
 #include <linux/irq.h>
 #include <linux/io.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
 
 #include <asm/smp_twd.h>
 #include <asm/localtimer.h>
@@ -284,37 +286,86 @@ static struct local_timer_ops twd_lt_ops __cpuinitdata = {
         .stop   = twd_timer_stop,
 };
 
-int __init twd_local_timer_register(struct twd_local_timer *tlt)
+static int __init twd_local_timer_common_register(void)
 {
         int err;
 
-        if (twd_base || twd_evt)
-                return -EBUSY;
-
-        twd_ppi = tlt->res[1].start;
-
         twd_evt = alloc_percpu(struct clock_event_device *);
-        twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
-        if (!twd_base || !twd_evt) {
+        if (!twd_evt) {
                 err = -ENOMEM;
-                goto out;
+                goto out_free;
         }
 
         err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
         if (err) {
                 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
-                goto out;
+                goto out_free;
         }
 
         err = local_timer_register(&twd_lt_ops);
         if (err)
-                goto out;
+                goto out_irq;
 
         return 0;
 
-out:
+out_irq:
+        free_percpu_irq(twd_ppi, twd_evt);
+out_free:
         iounmap(twd_base);
+        twd_base = NULL;
         free_percpu(twd_evt);
-        twd_base = twd_evt = NULL;
+
         return err;
 }
+
+int __init twd_local_timer_register(struct twd_local_timer *tlt)
+{
+        if (twd_base || twd_evt)
+                return -EBUSY;
+
+        twd_ppi = tlt->res[1].start;
+
+        twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
+        if (!twd_base)
+                return -ENOMEM;
+
+        return twd_local_timer_common_register();
+}
+
+#ifdef CONFIG_OF
+const static struct of_device_id twd_of_match[] __initconst = {
+        { .compatible = "arm,cortex-a9-twd-timer",      },
+        { .compatible = "arm,cortex-a5-twd-timer",      },
+        { .compatible = "arm,arm11mp-twd-timer",        },
+        { },
+};
+
+void __init twd_local_timer_of_register(void)
+{
+        struct device_node *np;
+        int err;
+
+        np = of_find_matching_node(NULL, twd_of_match);
+        if (!np) {
+                err = -ENODEV;
+                goto out;
+        }
+
+        twd_ppi = irq_of_parse_and_map(np, 0);
+        if (!twd_ppi) {
+                err = -EINVAL;
+                goto out;
+        }
+
+        twd_base = of_iomap(np, 0);
+        if (!twd_base) {
+                err = -ENOMEM;
+                goto out;
+        }
+
+        err = twd_local_timer_common_register();
+
+out:
+        WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
+}
+#endif