clocksource/drivers/fsl_ftm_timer: 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 let the caller unaware if 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 return back an error or success in the init
function.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/fsl_ftm_timer.c

@@ -316,15 +316,16 @@ static int __init ftm_calc_closest_round_cyc(unsigned long freq)
 	return 0;
 }
 
-static void __init ftm_timer_init(struct device_node *np)
+static int __init ftm_timer_init(struct device_node *np)
 {
 	unsigned long freq;
-	int irq;
+	int ret, irq;
 
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 	if (!priv)
-		return;
+		return -ENOMEM;
 
+	ret = -ENXIO;
 	priv->clkevt_base = of_iomap(np, 0);
 	if (!priv->clkevt_base) {
 		pr_err("ftm: unable to map event timer registers\n");
@@ -337,6 +338,7 @@ static void __init ftm_timer_init(struct device_node *np)
 		goto err;
 	}
 
+	ret = -EINVAL;
 	irq = irq_of_parse_and_map(np, 0);
 	if (irq <= 0) {
 		pr_err("ftm: unable to get IRQ from DT, %d\n", irq);
@@ -349,18 +351,22 @@ static void __init ftm_timer_init(struct device_node *np)
 	if (!freq)
 		goto err;
 
-	if (ftm_calc_closest_round_cyc(freq))
+	ret = ftm_calc_closest_round_cyc(freq);
+	if (ret)
 		goto err;
 
-	if (ftm_clocksource_init(freq))
+	ret = ftm_clocksource_init(freq);
+	if (ret)
 		goto err;
 
-	if (ftm_clockevent_init(freq, irq))
+	ret = ftm_clockevent_init(freq, irq);
+	if (ret)
 		goto err;
 
-	return;
+	return 0;
 
 err:
 	kfree(priv);
+	return ret;
 }
-CLOCKSOURCE_OF_DECLARE(flextimer, "fsl,ftm-timer", ftm_timer_init);
+CLOCKSOURCE_OF_DECLARE_RET(flextimer, "fsl,ftm-timer", ftm_timer_init);