clocksource: tcb_clksrc: Improve driver robustness

Check function return values to avoid false positive driver init.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/tcb_clksrc.c

@@ -184,11 +184,18 @@ static struct irqaction tc_irqaction = {
 	.handler	= ch2_irq,
 };
 
-static void __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
+static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
 {
+	int ret;
 	struct clk *t2_clk = tc->clk[2];
 	int irq = tc->irq[2];
 
+	/* try to enable t2 clk to avoid future errors in mode change */
+	ret = clk_prepare_enable(t2_clk);
+	if (ret)
+		return ret;
+	clk_disable_unprepare(t2_clk);
+
 	clkevt.regs = tc->regs;
 	clkevt.clk = t2_clk;
 	tc_irqaction.dev_id = &clkevt;
@@ -197,16 +204,21 @@ static void __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
 
 	clkevt.clkevt.cpumask = cpumask_of(0);
 
+	ret = setup_irq(irq, &tc_irqaction);
+	if (ret)
+		return ret;
+
 	clockevents_config_and_register(&clkevt.clkevt, 32768, 1, 0xffff);
 
-	setup_irq(irq, &tc_irqaction);
+	return ret;
 }
 
 #else /* !CONFIG_GENERIC_CLOCKEVENTS */
 
-static void __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
+static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
 {
 	/* NOTHING */
+	return 0;
 }
 
 #endif
@@ -328,13 +340,24 @@ static int __init tcb_clksrc_init(void)
 	}
 
 	/* and away we go! */
-	clocksource_register_hz(&clksrc, divided_rate);
+	ret = clocksource_register_hz(&clksrc, divided_rate);
+	if (ret)
+		goto err_disable_t1;
 
 	/* channel 2:  periodic and oneshot timer support */
-	setup_clkevents(tc, clk32k_divisor_idx);
+	ret = setup_clkevents(tc, clk32k_divisor_idx);
+	if (ret)
+		goto err_unregister_clksrc;
 
 	return 0;
 
+err_unregister_clksrc:
+	clocksource_unregister(&clksrc);
+
+err_disable_t1:
+	if (!tc->tcb_config || tc->tcb_config->counter_width != 32)
+		clk_disable_unprepare(tc->clk[1]);
+
 err_disable_t0:
 	clk_disable_unprepare(t0_clk);