diff options
| author | Peter Cai <peter@typeblog.net> | 2022-02-02 13:04:04 -0500 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2022-02-11 09:00:47 -0500 |
| commit | 80d4c02b9324e7e0049582142474c9cc8630e27c (patch) | |
| tree | 44d406100f1ffd0cbf16f766a74560f3cac9491d /drivers/button | |
| parent | 0290146943af203c1a9e332e19ec76b414b0a771 (diff) | |
button: adc: set state to pressed when the voltage is closest to nominal
In the Linux implementation of adc-keys
(drivers/input/keyboard/adc-keys.c), `press-threshold-microvolt` is not
really interpreted as a threshold, but rather as the "nominal voltage"
of the button. When the voltage read from the ADC is closest to a
button's `press-threshold-microvolt`, the button is considered pressed.
This patch reconciles the behavior of button-adc with Linux's adc-keys
such that device trees can be synchronized with minimal modifications.
Signed-off-by: Peter Cai <peter@typeblog.net>
Diffstat (limited to 'drivers/button')
| -rw-r--r-- | drivers/button/button-adc.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/drivers/button/button-adc.c b/drivers/button/button-adc.c index fd896c76f9..9c24c960e6 100644 --- a/drivers/button/button-adc.c +++ b/drivers/button/button-adc.c @@ -55,7 +55,7 @@ static int button_adc_of_to_plat(struct udevice *dev) struct button_uc_plat *uc_plat = dev_get_uclass_plat(dev); struct button_adc_priv *priv = dev_get_priv(dev); struct ofnode_phandle_args args; - u32 threshold, up_threshold, t; + u32 down_threshold = 0, up_threshold, voltage, t; ofnode node; int ret; @@ -78,7 +78,7 @@ static int button_adc_of_to_plat(struct udevice *dev) return ret; ret = ofnode_read_u32(dev_ofnode(dev), "press-threshold-microvolt", - &threshold); + &voltage); if (ret) return ret; @@ -87,13 +87,24 @@ static int button_adc_of_to_plat(struct udevice *dev) if (ret) return ret; - if (t > threshold) + if (t > voltage && t < up_threshold) up_threshold = t; + else if (t < voltage && t > down_threshold) + down_threshold = t; } priv->channel = args.args[0]; - priv->min = threshold; - priv->max = up_threshold; + + /* + * Define the voltage range such that the button is only pressed + * when the voltage is closest to its own press-threshold-microvolt + */ + if (down_threshold == 0) + priv->min = 0; + else + priv->min = down_threshold + (voltage - down_threshold) / 2; + + priv->max = voltage + (up_threshold - voltage) / 2; return ret; } |