From: Sascha Hauer <s.hauer@pengutronix.de>
To: Barebox List <barebox@lists.infradead.org>
Subject: [PATCH] input: gpio-keys: implement debouncing
Date: Mon, 14 Dec 2015 12:46:21 +0100 [thread overview]
Message-ID: <1450093581-17714-1-git-send-email-s.hauer@pengutronix.de> (raw)
The gpio-keys driver often generates multiple events on a single buttong
press. Implement debouncing. The default debouncing time is 20ms and can
be configured with the "debounce-interval" device tree property.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
drivers/input/gpio_keys.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/drivers/input/gpio_keys.c b/drivers/input/gpio_keys.c
index d017594..5b03fd7 100644
--- a/drivers/input/gpio_keys.c
+++ b/drivers/input/gpio_keys.c
@@ -21,6 +21,9 @@ struct gpio_key {
int active_low;
int previous_state;
+
+ int debounce_interval;
+ u64 debounce_start;
};
struct gpio_keys {
@@ -60,11 +63,17 @@ static void gpio_key_poller(struct poller_struct *poller)
gb = &gk->buttons[i];
val = gpio_get_value(gb->gpio);
- if (val != gb->previous_state && val != gb->active_low) {
- kfifo_put(gk->recv_fifo, (u_char*)&gb->code, sizeof(int));
- debug("pressed gpio(%d) as %d\n", gb->gpio, gb->code);
+ if (!is_timeout(gb->debounce_start, gb->debounce_interval * MSECOND))
+ continue;
+
+ if (val != gb->previous_state) {
+ gb->debounce_start = get_time_ns();
+ if (val != gb->active_low) {
+ kfifo_put(gk->recv_fifo, (u_char*)&gb->code, sizeof(int));
+ debug("pressed gpio(%d) as %d\n", gb->gpio, gb->code);
+ }
+ gb->previous_state = val;
}
- gb->previous_state = val;
}
}
@@ -111,6 +120,7 @@ static int gpio_keys_probe_pdata(struct gpio_keys *gk, struct device_d *dev)
gk->buttons[i].gpio = pdata->buttons[i].gpio;
gk->buttons[i].code = pdata->buttons[i].code;
gk->buttons[i].active_low = pdata->buttons[i].active_low;
+ gk->buttons[i].debounce_interval = 20;
}
return 0;
@@ -142,6 +152,11 @@ static int gpio_keys_probe_dt(struct gpio_keys *gk, struct device_d *dev)
if (ret)
return ret;
+ gk->buttons[i].debounce_interval = 20;
+
+ of_property_read_u32(npkey, "debounce-interval",
+ &gk->buttons[i].debounce_interval);
+
gk->buttons[i].code = keycode;
i++;
--
2.6.2
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