clocksource/drivers/tango_xtal: Convert init function to return error

The init functions do not return any error. They behave as the following:

  - panic, thus leading to a kernel crash while another timer may work and
       make the system boot up correctly

  or

  - print an error and leave the caller unaware of the state of the system

Change that by converting the init functions to return an error conforming
to the CLOCKSOURCE_OF_RET prototype.

Proper error handling (rollback, errno value) will be changed later case
by case, thus this change just returns an error code from the init function.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>

drivers/clocksource/tango_xtal.c

@@ -19,7 +19,7 @@ static u64 notrace read_sched_clock(void)
 	return read_xtal_counter();
 }
 
-static void __init tango_clocksource_init(struct device_node *np)
+static int __init tango_clocksource_init(struct device_node *np)
 {
 	struct clk *clk;
 	int xtal_freq, ret;
@@ -27,13 +27,13 @@ static void __init tango_clocksource_init(struct device_node *np)
 	xtal_in_cnt = of_iomap(np, 0);
 	if (xtal_in_cnt == NULL) {
 		pr_err("%s: invalid address\n", np->full_name);
-		return;
+		return -ENXIO;
 	}
 
 	clk = of_clk_get(np, 0);
 	if (IS_ERR(clk)) {
 		pr_err("%s: invalid clock\n", np->full_name);
-		return;
+		return PTR_ERR(clk);
 	}
 
 	xtal_freq = clk_get_rate(clk);
@@ -44,11 +44,13 @@ static void __init tango_clocksource_init(struct device_node *np)
 				    32, clocksource_mmio_readl_up);
 	if (ret) {
 		pr_err("%s: registration failed\n", np->full_name);
-		return;
+		return ret;
 	}
 
 	sched_clock_register(read_sched_clock, 32, xtal_freq);
 	register_current_timer_delay(&delay_timer);
+
+	return 0;
 }
 
-CLOCKSOURCE_OF_DECLARE(tango, "sigma,tick-counter", tango_clocksource_init);
+CLOCKSOURCE_OF_DECLARE_RET(tango, "sigma,tick-counter", tango_clocksource_init);