leds: bcm6328: improve blink support

BCM6328 controller has a margin of 20ms per blink step, which means that
we can only set it to 20, 40, 60 ... 1260 ms (0x3f * 20ms).
However, when checking if delay_on == delay_off, we were not considering
the case when the user had set delay_on=20 and delay_off=21, since this
will cause the driver to fallback to software blinking.
This update fixes this issue and improves blink steps by rounding them
in a more sensible way. Now 30-49ms is rounded to 40 ms, and previous
behaviour implied 40-59ms being rounded to 40 ms.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

drivers/leds/leds-bcm6328.c

@@ -140,6 +140,18 @@ static void bcm6328_led_set(struct led_classdev *led_cdev,
 	spin_unlock_irqrestore(led->lock, flags);
 }
 
+static unsigned long bcm6328_blink_delay(unsigned long delay)
+{
+	unsigned long bcm6328_delay;
+
+	bcm6328_delay = delay + BCM6328_LED_INTERVAL_MS / 2;
+	bcm6328_delay = bcm6328_delay / BCM6328_LED_INTERVAL_MS;
+	if (bcm6328_delay == 0)
+		bcm6328_delay = 1;
+
+	return bcm6328_delay;
+}
+
 static int bcm6328_blink_set(struct led_classdev *led_cdev,
 			     unsigned long *delay_on, unsigned long *delay_off)
 {
@@ -153,16 +165,14 @@ static int bcm6328_blink_set(struct led_classdev *led_cdev,
 	if (!*delay_off)
 		*delay_off = BCM6328_LED_DEF_DELAY;
 
-	if (*delay_on != *delay_off) {
+	delay = bcm6328_blink_delay(*delay_on);
+	if (delay != bcm6328_blink_delay(*delay_off)) {
 		dev_dbg(led_cdev->dev,
 			"fallback to soft blinking (delay_on != delay_off)\n");
 		return -EINVAL;
 	}
 
-	delay = *delay_on / BCM6328_LED_INTERVAL_MS;
-	if (delay == 0) {
-		delay = 1;
-	} else if (delay > BCM6328_LED_INTV_MASK) {
+	if (delay > BCM6328_LED_INTV_MASK) {
 		dev_dbg(led_cdev->dev,
 			"fallback to soft blinking (delay > %ums)\n",
 			BCM6328_LED_INTV_MASK * BCM6328_LED_INTERVAL_MS);