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 <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>

Documentation/devicetree/bindings/arm/twd.txt

···
+* ARM Timer Watchdog
+
+ARM 11MP, Cortex-A5 and Cortex-A9 are often associated with a per-core
+Timer-Watchdog (aka TWD), which provides both a per-cpu local timer
+and watchdog.
+
+The TWD is usually attached to a GIC to deliver its two per-processor
+interrupts.
+
+** Timer node required properties:
+
+- compatible : Should be one of:
+	"arm,cortex-a9-twd-timer"
+	"arm,cortex-a5-twd-timer"
+	"arm,arm11mp-twd-timer"
+
+- interrupts : One interrupt to each core
+
+- reg : Specify the base address and the size of the TWD timer
+	register window.
+
+Example:
+
+	twd-timer@2c000600 {
+		compatible = "arm,arm11mp-twd-timer"";
+		reg = <0x2c000600 0x20>;
+		interrupts = <1 13 0xf01>;
+	};
+
+** Watchdog node properties:
+
+- compatible : Should be one of:
+	"arm,cortex-a9-twd-wdt"
+	"arm,cortex-a5-twd-wdt"
+	"arm,arm11mp-twd-wdt"
+
+- interrupts : One interrupt to each core
+
+- reg : Specify the base address and the size of the TWD watchdog
+	register window.
+
+Example:
+
+	twd-watchdog@2c000620 {
+		compatible = "arm,arm11mp-twd-wdt";
+		reg = <0x2c000620 0x20>;
+		interrupts = <1 14 0xf01>;
+	};

arch/arm/include/asm/smp_twd.h

···
 
 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

arch/arm/kernel/smp_twd.c

···
 #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>
···
 	.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