ARM: tegra: enhance timer.c to get IRQ info from device tree

Modify Tegra's timer code to parse the Tegra timer IRQ from device tree,
and to instantiate the TWD from device tree, rather than relying on hard-
coded values from <mach/irqs.h>.
Signed-off-by: Stephen Warren <swarren@nvidia.com>

arch/arm/mach-tegra/timer.c

@@ -26,13 +26,12 @@
 #include <linux/clocksource.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/of_irq.h>
 
 #include <asm/mach/time.h>
 #include <asm/smp_twd.h>
 #include <asm/sched_clock.h>
 
-#include <mach/irqs.h>
-
 #include "board.h"
 #include "clock.h"
 #include "iomap.h"
@@ -158,30 +157,32 @@ static struct irqaction tegra_timer_irq = {
 	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_TRIGGER_HIGH,
 	.handler	= tegra_timer_interrupt,
 	.dev_id		= &tegra_clockevent,
-	.irq		= INT_TMR3,
 };
 
-#ifdef CONFIG_HAVE_ARM_TWD
-static DEFINE_TWD_LOCAL_TIMER(twd_local_timer,
-			      TEGRA_ARM_PERIF_BASE + 0x600,
-			      IRQ_LOCALTIMER);
-
-static void __init tegra_twd_init(void)
-{
-	int err = twd_local_timer_register(&twd_local_timer);
-	if (err)
-		pr_err("twd_local_timer_register failed %d\n", err);
-}
-#else
-#define tegra_twd_init()	do {} while(0)
-#endif
+static const struct of_device_id timer_match[] __initconst = {
+	{ .compatible = "nvidia,tegra20-timer" },
+	{}
+};
 
 static void __init tegra_init_timer(void)
 {
+	struct device_node *np;
 	struct clk *clk;
 	unsigned long rate;
 	int ret;
 
+	np = of_find_matching_node(NULL, timer_match);
+	if (!np) {
+		pr_err("Failed to find timer DT node\n");
+		BUG();
+	}
+
+	tegra_timer_irq.irq = irq_of_parse_and_map(np, 2);
+	if (tegra_timer_irq.irq <= 0) {
+		pr_err("Failed to map timer IRQ\n");
+		BUG();
+	}
+
 	clk = clk_get_sys("timer", NULL);
 	if (IS_ERR(clk)) {
 		pr_warn("Unable to get timer clock. Assuming 12Mhz input clock.\n");
@@ -201,6 +202,8 @@ static void __init tegra_init_timer(void)
 	else
 		clk_prepare_enable(clk);
 
+	of_node_put(np);
+
 	switch (rate) {
 	case 12000000:
 		timer_writel(0x000b, TIMERUS_USEC_CFG);
@@ -240,7 +243,9 @@ static void __init tegra_init_timer(void)
 	tegra_clockevent.cpumask = cpu_all_mask;
 	tegra_clockevent.irq = tegra_timer_irq.irq;
 	clockevents_register_device(&tegra_clockevent);
-	tegra_twd_init();
+#ifdef CONFIG_HAVE_ARM_TWD
+	twd_local_timer_of_register();
+#endif
 	register_persistent_clock(NULL, tegra_read_persistent_clock);
 }