clocksource/drivers/nomadik-mtu: 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/nomadik-mtu.c

@@ -193,10 +193,11 @@ static struct irqaction nmdk_timer_irq = {
 	.dev_id		= &nmdk_clkevt,
 };
 
-static void __init nmdk_timer_init(void __iomem *base, int irq,
+static int __init nmdk_timer_init(void __iomem *base, int irq,
 				   struct clk *pclk, struct clk *clk)
 {
 	unsigned long rate;
+	int ret;
 
 	mtu_base = base;
 
@@ -226,10 +227,12 @@ static void __init nmdk_timer_init(void __iomem *base, int irq,
 	/* Timer 0 is the free running clocksource */
 	nmdk_clksrc_reset();
 
-	if (clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
-			rate, 200, 32, clocksource_mmio_readl_down))
-		pr_err("timer: failed to initialize clock source %s\n",
-		       "mtu_0");
+	ret = clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
+				    rate, 200, 32, clocksource_mmio_readl_down);
+	if (ret) {
+		pr_err("timer: failed to initialize clock source %s\n", "mtu_0");
+		return ret;
+	}
 
 #ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK
 	sched_clock_register(nomadik_read_sched_clock, 32, rate);
@@ -244,9 +247,11 @@ static void __init nmdk_timer_init(void __iomem *base, int irq,
 	mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer;
 	mtu_delay_timer.freq = rate;
 	register_current_timer_delay(&mtu_delay_timer);
+
+	return 0;
 }
 
-static void __init nmdk_timer_of_init(struct device_node *node)
+static int __init nmdk_timer_of_init(struct device_node *node)
 {
 	struct clk *pclk;
 	struct clk *clk;
@@ -254,22 +259,30 @@ static void __init nmdk_timer_of_init(struct device_node *node)
 	int irq;
 
 	base = of_iomap(node, 0);
-	if (!base)
-		panic("Can't remap registers");
+	if (!base) {
+		pr_err("Can't remap registers");
+		return -ENXIO;
+	}
 
 	pclk = of_clk_get_by_name(node, "apb_pclk");
-	if (IS_ERR(pclk))
-		panic("could not get apb_pclk");
+	if (IS_ERR(pclk)) {
+		pr_err("could not get apb_pclk");
+		return PTR_ERR(pclk);
+	}
 
 	clk = of_clk_get_by_name(node, "timclk");
-	if (IS_ERR(clk))
-		panic("could not get timclk");
+	if (IS_ERR(clk)) {
+		pr_err("could not get timclk");
+		return PTR_ERR(clk);
+	}
 
 	irq = irq_of_parse_and_map(node, 0);
-	if (irq <= 0)
-		panic("Can't parse IRQ");
+	if (irq <= 0) {
+		pr_err("Can't parse IRQ");
+		return -EINVAL;
+	}
 
-	nmdk_timer_init(base, irq, pclk, clk);
+	return nmdk_timer_init(base, irq, pclk, clk);
 }
-CLOCKSOURCE_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu",
+CLOCKSOURCE_OF_DECLARE_RET(nomadik_mtu, "st,nomadik-mtu",
 		       nmdk_timer_of_init);