pwm: lpc18xx-sct: Test clock rate to avoid division by 0

The clk API may return 0 on clk_get_rate(), so we should check the
result before using it as a divisor.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-lpc18xx-sct.c

diff --git a/drivers/pwm/pwm-lpc18xx-sct.c b/drivers/pwm/pwm-lpc18xx-sct.c
index 9163085..9861fed 100644
--- a/drivers/pwm/pwm-lpc18xx-sct.c
+++ b/drivers/pwm/pwm-lpc18xx-sct.c
@@ -360,6 +360,11 @@
 	}
 
 	lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
+	if (!lpc18xx_pwm->clk_rate) {
+		dev_err(&pdev->dev, "pwm clock has no frequency\n");
+		ret = -EINVAL;
+		goto disable_pwmclk;
+	}
 
 	mutex_init(&lpc18xx_pwm->res_lock);
 	mutex_init(&lpc18xx_pwm->period_lock);