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authorDaniel Mack <daniel@caiaq.de>2009-03-04 23:27:14 -0800
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2009-03-08 16:35:53 -0700
commit73969ff0eda233f140bcbed1251431387b43f383 (patch)
treeb7dd2b670d9e03916b04469e9d38b71d69c6cd60 /drivers
parentb0ecc7309443dbcf1a0ce2d93f39f5d92c124d42 (diff)
Input: generic driver for rotary encoders on GPIOs
This patch adds a generic driver for rotary encoders connected to GPIO pins of a system. It relies on gpiolib and generic hardware irqs. The documentation that also comes with this patch explains the concept and how to use the driver. Signed-off-by: Daniel Mack <daniel@caiaq.de> Tested-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/input/misc/Kconfig11
-rw-r--r--drivers/input/misc/Makefile2
-rw-r--r--drivers/input/misc/rotary_encoder.c221
3 files changed, 234 insertions, 0 deletions
diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 67e5553f699..806d2e66d24 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -227,4 +227,15 @@ config INPUT_PCF50633_PMU
Say Y to include support for delivering PMU events via input
layer on NXP PCF50633.
+config INPUT_GPIO_ROTARY_ENCODER
+ tristate "Rotary encoders connected to GPIO pins"
+ depends on GPIOLIB && GENERIC_GPIO
+ help
+ Say Y here to add support for rotary encoders connected to GPIO lines.
+ Check file:Documentation/incput/rotary_encoder.txt for more
+ information.
+
+ To compile this driver as a module, choose M here: the
+ module will be called rotary_encoder.
+
endif
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index bb62e6efacf..e86cee66c91 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -22,3 +22,5 @@ obj-$(CONFIG_INPUT_UINPUT) += uinput.o
obj-$(CONFIG_INPUT_APANEL) += apanel.o
obj-$(CONFIG_INPUT_SGI_BTNS) += sgi_btns.o
obj-$(CONFIG_INPUT_PCF50633_PMU) += pcf50633-input.o
+obj-$(CONFIG_INPUT_GPIO_ROTARY_ENCODER) += rotary_encoder.o
+
diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
new file mode 100644
index 00000000000..5bb3ab51b8c
--- /dev/null
+++ b/drivers/input/misc/rotary_encoder.c
@@ -0,0 +1,221 @@
+/*
+ * rotary_encoder.c
+ *
+ * (c) 2009 Daniel Mack <daniel@caiaq.de>
+ *
+ * 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/init.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>
+
+#define DRV_NAME "rotary-encoder"
+
+struct rotary_encoder {
+ unsigned int irq_a;
+ unsigned int irq_b;
+ unsigned int pos;
+ unsigned int armed;
+ unsigned int dir;
+ struct input_dev *input;
+ struct rotary_encoder_platform_data *pdata;
+};
+
+static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
+{
+ struct rotary_encoder *encoder = dev_id;
+ struct rotary_encoder_platform_data *pdata = encoder->pdata;
+ int a = !!gpio_get_value(pdata->gpio_a);
+ int b = !!gpio_get_value(pdata->gpio_b);
+ int state;
+
+ a ^= pdata->inverted_a;
+ b ^= pdata->inverted_b;
+ state = (a << 1) | b;
+
+ switch (state) {
+
+ case 0x0:
+ if (!encoder->armed)
+ break;
+
+ if (encoder->dir) {
+ /* turning counter-clockwise */
+ encoder->pos += pdata->steps;
+ encoder->pos--;
+ encoder->pos %= pdata->steps;
+ } else {
+ /* turning clockwise */
+ encoder->pos++;
+ encoder->pos %= pdata->steps;
+ }
+
+ input_report_abs(encoder->input, pdata->axis, encoder->pos);
+ input_sync(encoder->input);
+
+ encoder->armed = 0;
+ break;
+
+ case 0x1:
+ case 0x2:
+ if (encoder->armed)
+ encoder->dir = state - 1;
+ break;
+
+ case 0x3:
+ encoder->armed = 1;
+ 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;
+ int err;
+
+ if (!pdata || !pdata->steps) {
+ dev_err(&pdev->dev, "invalid platform data\n");
+ return -ENOENT;
+ }
+
+ encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
+ input = input_allocate_device();
+ if (!encoder || !input) {
+ dev_err(&pdev->dev, "failed to allocate memory for device\n");
+ err = -ENOMEM;
+ goto exit_free_mem;
+ }
+
+ encoder->input = input;
+ encoder->pdata = pdata;
+ encoder->irq_a = gpio_to_irq(pdata->gpio_a);
+ encoder->irq_b = gpio_to_irq(pdata->gpio_b);
+
+ /* create and register the input driver */
+ input->name = pdev->name;
+ input->id.bustype = BUS_HOST;
+ input->dev.parent = &pdev->dev;
+ input->evbit[0] = BIT_MASK(EV_ABS);
+ input_set_abs_params(encoder->input,
+ pdata->axis, 0, pdata->steps, 0, 1);
+
+ err = input_register_device(input);
+ if (err) {
+ dev_err(&pdev->dev, "failed to register input device\n");
+ goto exit_free_mem;
+ }
+
+ /* request the GPIOs */
+ err = gpio_request(pdata->gpio_a, DRV_NAME);
+ if (err) {
+ dev_err(&pdev->dev, "unable to request GPIO %d\n",
+ pdata->gpio_a);
+ goto exit_unregister_input;
+ }
+
+ err = gpio_request(pdata->gpio_b, DRV_NAME);
+ if (err) {
+ dev_err(&pdev->dev, "unable to request GPIO %d\n",
+ pdata->gpio_b);
+ goto exit_free_gpio_a;
+ }
+
+ /* request the IRQs */
+ err = request_irq(encoder->irq_a, &rotary_encoder_irq,
+ IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
+ DRV_NAME, encoder);
+ if (err) {
+ dev_err(&pdev->dev, "unable to request IRQ %d\n",
+ encoder->irq_a);
+ goto exit_free_gpio_b;
+ }
+
+ err = request_irq(encoder->irq_b, &rotary_encoder_irq,
+ IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
+ DRV_NAME, encoder);
+ if (err) {
+ dev_err(&pdev->dev, "unable to request IRQ %d\n",
+ encoder->irq_b);
+ goto exit_free_irq_a;
+ }
+
+ platform_set_drvdata(pdev, encoder);
+
+ return 0;
+
+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_unregister_input:
+ input_unregister_device(input);
+ input = NULL; /* so we don't try to free it */
+exit_free_mem:
+ input_free_device(input);
+ kfree(encoder);
+ return err;
+}
+
+static int __devexit rotary_encoder_remove(struct platform_device *pdev)
+{
+ struct rotary_encoder *encoder = platform_get_drvdata(pdev);
+ struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
+
+ 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);
+ platform_set_drvdata(pdev, NULL);
+ kfree(encoder);
+
+ return 0;
+}
+
+static struct platform_driver rotary_encoder_driver = {
+ .probe = rotary_encoder_probe,
+ .remove = __devexit_p(rotary_encoder_remove),
+ .driver = {
+ .name = DRV_NAME,
+ .owner = THIS_MODULE,
+ }
+};
+
+static int __init rotary_encoder_init(void)
+{
+ return platform_driver_register(&rotary_encoder_driver);
+}
+
+static void __exit rotary_encoder_exit(void)
+{
+ platform_driver_unregister(&rotary_encoder_driver);
+}
+
+module_init(rotary_encoder_init);
+module_exit(rotary_encoder_exit);
+
+MODULE_ALIAS("platform:" DRV_NAME);
+MODULE_DESCRIPTION("GPIO rotary encoder driver");
+MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
+MODULE_LICENSE("GPL v2");
+