diff options
| -rw-r--r-- | Documentation/input/rotary-encoder.txt | 13 | ||||
| -rw-r--r-- | drivers/input/misc/rotary_encoder.c | 42 | ||||
| -rw-r--r-- | include/linux/rotary_encoder.h | 1 |
3 files changed, 53 insertions, 3 deletions
diff --git a/Documentation/input/rotary-encoder.txt b/Documentation/input/rotary-encoder.txt index 943e8f6f2b1..92e68bce13a 100644 --- a/Documentation/input/rotary-encoder.txt +++ b/Documentation/input/rotary-encoder.txt @@ -9,6 +9,9 @@ peripherals with two wires. The outputs are phase-shifted by 90 degrees and by triggering on falling and rising edges, the turn direction can be determined. +Some encoders have both outputs low in stable states, whereas others also have +a stable state with both outputs high (half-period mode). + The phase diagram of these two outputs look like this: _____ _____ _____ @@ -26,6 +29,8 @@ The phase diagram of these two outputs look like this: |<-------->| one step + |<-->| + one step (half-period mode) For more information, please see http://en.wikipedia.org/wiki/Rotary_encoder @@ -34,6 +39,13 @@ For more information, please see 1. Events / state machine ------------------------- +In half-period mode, state a) and c) above are used to determine the +rotational direction based on the last stable state. Events are reported in +states b) and d) given that the new stable state is different from the last +(i.e. the rotation was not reversed half-way). + +Otherwise, the following apply: + a) Rising edge on channel A, channel B in low state This state is used to recognize a clockwise turn @@ -96,6 +108,7 @@ static struct rotary_encoder_platform_data my_rotary_encoder_info = { .gpio_b = GPIO_ROTARY_B, .inverted_a = 0, .inverted_b = 0, + .half_period = false, }; static struct platform_device rotary_encoder_device = { diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c index 077b80bdca6..2c8b84dd9da 100644 --- a/drivers/input/misc/rotary_encoder.c +++ b/drivers/input/misc/rotary_encoder.c @@ -2,6 +2,7 @@ * rotary_encoder.c * * (c) 2009 Daniel Mack <daniel@caiaq.de> + * Copyright (C) 2011 Johan Hovold <jhovold@gmail.com> * * state machine code inspired by code from Tim Ruetz * @@ -38,6 +39,8 @@ struct rotary_encoder { bool armed; unsigned char dir; /* 0 - clockwise, 1 - CCW */ + + char last_stable; }; static int rotary_encoder_get_state(struct rotary_encoder_platform_data *pdata) @@ -112,11 +115,37 @@ static irqreturn_t rotary_encoder_irq(int irq, void *dev_id) return IRQ_HANDLED; } +static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id) +{ + struct rotary_encoder *encoder = dev_id; + int state; + + state = rotary_encoder_get_state(encoder->pdata); + + switch (state) { + case 0x00: + case 0x03: + if (state != encoder->last_stable) { + rotary_encoder_report_event(encoder); + encoder->last_stable = state; + } + break; + + case 0x01: + case 0x02: + encoder->dir = (encoder->last_stable + state) & 0x01; + break; + } + + return IRQ_HANDLED; +} + static int __devinit rotary_encoder_probe(struct platform_device *pdev) { struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data; struct rotary_encoder *encoder; struct input_dev *input; + irq_handler_t handler; int err; if (!pdata) { @@ -187,7 +216,14 @@ static int __devinit rotary_encoder_probe(struct platform_device *pdev) } /* request the IRQs */ - err = request_irq(encoder->irq_a, &rotary_encoder_irq, + if (pdata->half_period) { + handler = &rotary_encoder_half_period_irq; + encoder->last_stable = rotary_encoder_get_state(pdata); + } else { + handler = &rotary_encoder_irq; + } + + err = request_irq(encoder->irq_a, handler, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, DRV_NAME, encoder); if (err) { @@ -196,7 +232,7 @@ static int __devinit rotary_encoder_probe(struct platform_device *pdev) goto exit_free_gpio_b; } - err = request_irq(encoder->irq_b, &rotary_encoder_irq, + err = request_irq(encoder->irq_b, handler, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, DRV_NAME, encoder); if (err) { @@ -264,5 +300,5 @@ module_exit(rotary_encoder_exit); MODULE_ALIAS("platform:" DRV_NAME); MODULE_DESCRIPTION("GPIO rotary encoder driver"); -MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>"); +MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold"); MODULE_LICENSE("GPL v2"); diff --git a/include/linux/rotary_encoder.h b/include/linux/rotary_encoder.h index 215278b8df2..3f594dce571 100644 --- a/include/linux/rotary_encoder.h +++ b/include/linux/rotary_encoder.h @@ -10,6 +10,7 @@ struct rotary_encoder_platform_data { unsigned int inverted_b; bool relative_axis; bool rollover; + bool half_period; }; #endif /* __ROTARY_ENCODER_H__ */ |