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- /*
- * 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
- *
- * A generic driver for rotary encoders connected to GPIO lines.
- * See file:Documentation/input/rotary-encoder.txt for more information
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/interrupt.h>
- #include <linux/input.h>
- #include <linux/device.h>
- #include <linux/platform_device.h>
- #include <linux/gpio.h>
- #include <linux/rotary_encoder.h>
- #include <linux/slab.h>
- #include <linux/of.h>
- #include <linux/of_platform.h>
- #include <linux/of_gpio.h>
- #include <linux/pm.h>
- #define DRV_NAME "rotary-encoder"
- struct rotary_encoder {
- struct input_dev *input;
- const struct rotary_encoder_platform_data *pdata;
- unsigned int axis;
- unsigned int pos;
- unsigned int irq_a;
- unsigned int irq_b;
- bool armed;
- unsigned char dir; /* 0 - clockwise, 1 - CCW */
- char last_stable;
- };
- static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
- {
- int a = !!gpio_get_value(pdata->gpio_a);
- int b = !!gpio_get_value(pdata->gpio_b);
- a ^= pdata->inverted_a;
- b ^= pdata->inverted_b;
- return ((a << 1) | b);
- }
- static void rotary_encoder_report_event(struct rotary_encoder *encoder)
- {
- const struct rotary_encoder_platform_data *pdata = encoder->pdata;
- if (pdata->relative_axis) {
- input_report_rel(encoder->input,
- pdata->axis, encoder->dir ? -1 : 1);
- } else {
- unsigned int pos = encoder->pos;
- if (encoder->dir) {
- /* turning counter-clockwise */
- if (pdata->rollover)
- pos += pdata->steps;
- if (pos)
- pos--;
- } else {
- /* turning clockwise */
- if (pdata->rollover || pos < pdata->steps)
- pos++;
- }
- if (pdata->rollover)
- pos %= pdata->steps;
- encoder->pos = pos;
- input_report_abs(encoder->input, pdata->axis, encoder->pos);
- }
- input_sync(encoder->input);
- }
- static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
- {
- struct rotary_encoder *encoder = dev_id;
- int state;
- state = rotary_encoder_get_state(encoder->pdata);
- switch (state) {
- case 0x0:
- if (encoder->armed) {
- rotary_encoder_report_event(encoder);
- encoder->armed = false;
- }
- break;
- case 0x1:
- case 0x2:
- if (encoder->armed)
- encoder->dir = state - 1;
- break;
- case 0x3:
- encoder->armed = true;
- break;
- }
- 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 irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
- {
- struct rotary_encoder *encoder = dev_id;
- unsigned char sum;
- int state;
- state = rotary_encoder_get_state(encoder->pdata);
- /*
- * We encode the previous and the current state using a byte.
- * The previous state in the MSB nibble, the current state in the LSB
- * nibble. Then use a table to decide the direction of the turn.
- */
- sum = (encoder->last_stable << 4) + state;
- switch (sum) {
- case 0x31:
- case 0x10:
- case 0x02:
- case 0x23:
- encoder->dir = 0; /* clockwise */
- break;
- case 0x13:
- case 0x01:
- case 0x20:
- case 0x32:
- encoder->dir = 1; /* counter-clockwise */
- break;
- default:
- /*
- * Ignore all other values. This covers the case when the
- * state didn't change (a spurious interrupt) and the
- * cases where the state changed by two steps, making it
- * impossible to tell the direction.
- *
- * In either case, don't report any event and save the
- * state for later.
- */
- goto out;
- }
- rotary_encoder_report_event(encoder);
- out:
- encoder->last_stable = state;
- return IRQ_HANDLED;
- }
- #ifdef CONFIG_OF
- static const struct of_device_id rotary_encoder_of_match[] = {
- { .compatible = "rotary-encoder", },
- { },
- };
- MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
- static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct device *dev)
- {
- const struct of_device_id *of_id =
- of_match_device(rotary_encoder_of_match, dev);
- struct device_node *np = dev->of_node;
- struct rotary_encoder_platform_data *pdata;
- enum of_gpio_flags flags;
- int error;
- if (!of_id || !np)
- return NULL;
- pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
- GFP_KERNEL);
- if (!pdata)
- return ERR_PTR(-ENOMEM);
- of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
- of_property_read_u32(np, "linux,axis", &pdata->axis);
- pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
- pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
- pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
- pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
- pdata->relative_axis =
- of_property_read_bool(np, "rotary-encoder,relative-axis");
- pdata->rollover = of_property_read_bool(np, "rotary-encoder,rollover");
- error = of_property_read_u32(np, "rotary-encoder,steps-per-period",
- &pdata->steps_per_period);
- if (error) {
- /*
- * The 'half-period' property has been deprecated, you must use
- * 'steps-per-period' and set an appropriate value, but we still
- * need to parse it to maintain compatibility.
- */
- if (of_property_read_bool(np, "rotary-encoder,half-period")) {
- pdata->steps_per_period = 2;
- } else {
- /* Fallback to one step per period behavior */
- pdata->steps_per_period = 1;
- }
- }
- pdata->wakeup_source = of_property_read_bool(np, "wakeup-source");
- return pdata;
- }
- #else
- static inline struct rotary_encoder_platform_data *
- rotary_encoder_parse_dt(struct device *dev)
- {
- return NULL;
- }
- #endif
- static int rotary_encoder_probe(struct platform_device *pdev)
- {
- struct device *dev = &pdev->dev;
- const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
- struct rotary_encoder *encoder;
- struct input_dev *input;
- irq_handler_t handler;
- int err;
- if (!pdata) {
- pdata = rotary_encoder_parse_dt(dev);
- if (IS_ERR(pdata))
- return PTR_ERR(pdata);
- if (!pdata) {
- dev_err(dev, "missing platform data\n");
- return -EINVAL;
- }
- }
- encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
- input = input_allocate_device();
- if (!encoder || !input) {
- err = -ENOMEM;
- goto exit_free_mem;
- }
- encoder->input = input;
- encoder->pdata = pdata;
- input->name = pdev->name;
- input->id.bustype = BUS_HOST;
- input->dev.parent = dev;
- if (pdata->relative_axis) {
- input->evbit[0] = BIT_MASK(EV_REL);
- input->relbit[0] = BIT_MASK(pdata->axis);
- } else {
- input->evbit[0] = BIT_MASK(EV_ABS);
- input_set_abs_params(encoder->input,
- pdata->axis, 0, pdata->steps, 0, 1);
- }
- /* request the GPIOs */
- err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
- if (err) {
- dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
- goto exit_free_mem;
- }
- err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
- if (err) {
- dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
- goto exit_free_gpio_a;
- }
- encoder->irq_a = gpio_to_irq(pdata->gpio_a);
- encoder->irq_b = gpio_to_irq(pdata->gpio_b);
- switch (pdata->steps_per_period) {
- case 4:
- handler = &rotary_encoder_quarter_period_irq;
- encoder->last_stable = rotary_encoder_get_state(pdata);
- break;
- case 2:
- handler = &rotary_encoder_half_period_irq;
- encoder->last_stable = rotary_encoder_get_state(pdata);
- break;
- case 1:
- handler = &rotary_encoder_irq;
- break;
- default:
- dev_err(dev, "'%d' is not a valid steps-per-period value\n",
- pdata->steps_per_period);
- err = -EINVAL;
- goto exit_free_gpio_b;
- }
- err = request_irq(encoder->irq_a, handler,
- IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
- DRV_NAME, encoder);
- if (err) {
- dev_err(dev, "unable to request IRQ %d\n", encoder->irq_a);
- goto exit_free_gpio_b;
- }
- err = request_irq(encoder->irq_b, handler,
- IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
- DRV_NAME, encoder);
- if (err) {
- dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
- goto exit_free_irq_a;
- }
- err = input_register_device(input);
- if (err) {
- dev_err(dev, "failed to register input device\n");
- goto exit_free_irq_b;
- }
- device_init_wakeup(&pdev->dev, pdata->wakeup_source);
- platform_set_drvdata(pdev, encoder);
- return 0;
- exit_free_irq_b:
- free_irq(encoder->irq_b, encoder);
- exit_free_irq_a:
- free_irq(encoder->irq_a, encoder);
- exit_free_gpio_b:
- gpio_free(pdata->gpio_b);
- exit_free_gpio_a:
- gpio_free(pdata->gpio_a);
- exit_free_mem:
- input_free_device(input);
- kfree(encoder);
- if (!dev_get_platdata(&pdev->dev))
- kfree(pdata);
- return err;
- }
- static int rotary_encoder_remove(struct platform_device *pdev)
- {
- struct rotary_encoder *encoder = platform_get_drvdata(pdev);
- const struct rotary_encoder_platform_data *pdata = encoder->pdata;
- device_init_wakeup(&pdev->dev, false);
- free_irq(encoder->irq_a, encoder);
- free_irq(encoder->irq_b, encoder);
- gpio_free(pdata->gpio_a);
- gpio_free(pdata->gpio_b);
- input_unregister_device(encoder->input);
- kfree(encoder);
- if (!dev_get_platdata(&pdev->dev))
- kfree(pdata);
- return 0;
- }
- #ifdef CONFIG_PM_SLEEP
- static int rotary_encoder_suspend(struct device *dev)
- {
- struct rotary_encoder *encoder = dev_get_drvdata(dev);
- if (device_may_wakeup(dev)) {
- enable_irq_wake(encoder->irq_a);
- enable_irq_wake(encoder->irq_b);
- }
- return 0;
- }
- static int rotary_encoder_resume(struct device *dev)
- {
- struct rotary_encoder *encoder = dev_get_drvdata(dev);
- if (device_may_wakeup(dev)) {
- disable_irq_wake(encoder->irq_a);
- disable_irq_wake(encoder->irq_b);
- }
- return 0;
- }
- #endif
- static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
- rotary_encoder_suspend, rotary_encoder_resume);
- static struct platform_driver rotary_encoder_driver = {
- .probe = rotary_encoder_probe,
- .remove = rotary_encoder_remove,
- .driver = {
- .name = DRV_NAME,
- .pm = &rotary_encoder_pm_ops,
- .of_match_table = of_match_ptr(rotary_encoder_of_match),
- }
- };
- module_platform_driver(rotary_encoder_driver);
- MODULE_ALIAS("platform:" DRV_NAME);
- MODULE_DESCRIPTION("GPIO rotary encoder driver");
- MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
- MODULE_LICENSE("GPL v2");
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