* [PATCH 2/3] counter: add GPIO-based quadrature encoder driver
2026-04-16 20:48 [PATCH 0/3] counter: add GPIO-based quadrature encoder driver Wadim Mueller
2026-04-16 20:48 ` [PATCH 1/3] dt-bindings: counter: add gpio-quadrature-encoder binding Wadim Mueller
@ 2026-04-16 20:48 ` Wadim Mueller
2026-04-16 20:48 ` [PATCH 3/3] MAINTAINERS: add entry for GPIO quadrature encoder counter driver Wadim Mueller
2 siblings, 0 replies; 5+ messages in thread
From: Wadim Mueller @ 2026-04-16 20:48 UTC (permalink / raw)
To: wbg
Cc: robh, krzk+dt, conor+dt, linux-iio, devicetree, linux-kernel,
Wadim Mueller
Add a platform driver that turns ordinary GPIOs into a quadrature
encoder counter device. The driver requests edge-triggered interrupts
on the A and B (and optional Index) GPIOs and decodes the quadrature
signal in software using a classic state-table approach.
Supported counting modes:
- Quadrature X1 (count on A rising edge only)
- Quadrature X2 (count on both A edges)
- Quadrature X4 (count on every A and B edge)
- Pulse-direction (A = pulse, B = direction)
An optional index signal resets the count to zero on its rising edge
when enabled through sysfs. A configurable ceiling clamps the count
to [0, ceiling].
Signed-off-by: Wadim Mueller <wafgo01@gmail.com>
---
drivers/counter/Kconfig | 15 +
drivers/counter/Makefile | 1 +
drivers/counter/gpio-quadrature-encoder.c | 710 ++++++++++++++++++++++
3 files changed, 726 insertions(+)
create mode 100644 drivers/counter/gpio-quadrature-encoder.c
diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
index d30d22dfe..72c5c8159 100644
--- a/drivers/counter/Kconfig
+++ b/drivers/counter/Kconfig
@@ -68,6 +68,21 @@ config INTEL_QEP
To compile this driver as a module, choose M here: the module
will be called intel-qep.
+config GPIO_QUADRATURE_ENCODER
+ tristate "GPIO-based quadrature encoder counter driver"
+ depends on GPIOLIB
+ help
+ Select this option to enable the GPIO-based quadrature encoder
+ counter driver. It reads A/B quadrature signals and an optional
+ index pulse via edge-triggered GPIO interrupts, supporting X1, X2,
+ X4 quadrature decoding and pulse-direction mode.
+
+ This is useful on SoCs that lack a dedicated hardware quadrature
+ decoder or where the encoder is wired to generic GPIO pins.
+
+ To compile this driver as a module, choose M here: the
+ module will be called gpio-quadrature-encoder.
+
config INTERRUPT_CNT
tristate "Interrupt counter driver"
depends on GPIOLIB
diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile
index fa3c1d08f..2bef64d10 100644
--- a/drivers/counter/Makefile
+++ b/drivers/counter/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_STM32_TIMER_CNT) += stm32-timer-cnt.o
obj-$(CONFIG_STM32_LPTIMER_CNT) += stm32-lptimer-cnt.o
obj-$(CONFIG_TI_EQEP) += ti-eqep.o
obj-$(CONFIG_FTM_QUADDEC) += ftm-quaddec.o
+obj-$(CONFIG_GPIO_QUADRATURE_ENCODER) += gpio-quadrature-encoder.o
obj-$(CONFIG_MICROCHIP_TCB_CAPTURE) += microchip-tcb-capture.o
obj-$(CONFIG_INTEL_QEP) += intel-qep.o
obj-$(CONFIG_TI_ECAP_CAPTURE) += ti-ecap-capture.o
diff --git a/drivers/counter/gpio-quadrature-encoder.c b/drivers/counter/gpio-quadrature-encoder.c
new file mode 100644
index 000000000..0822f0a8a
--- /dev/null
+++ b/drivers/counter/gpio-quadrature-encoder.c
@@ -0,0 +1,710 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GPIO-based Quadrature Encoder Counter Driver
+ *
+ * Reads quadrature encoder signals (A, B, and optional Index) via GPIOs.
+ * Supports X1, X2, X4 quadrature decoding and pulse-direction mode.
+ *
+ * Copyright (C) 2026 CMBlu Energy AG
+ * Author: Wadim Mueller <wafgo01@gmail.com>
+ */
+
+#include <linux/counter.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+enum gpio_qenc_function {
+ GPIO_QENC_FUNC_QUAD_X1 = 0,
+ GPIO_QENC_FUNC_QUAD_X2,
+ GPIO_QENC_FUNC_QUAD_X4,
+ GPIO_QENC_FUNC_PULSE_DIR,
+};
+
+enum gpio_qenc_signal_id {
+ GPIO_QENC_SIGNAL_A = 0,
+ GPIO_QENC_SIGNAL_B,
+ GPIO_QENC_SIGNAL_INDEX,
+};
+
+struct gpio_qenc_priv {
+ struct gpio_desc *gpio_a;
+ struct gpio_desc *gpio_b;
+ struct gpio_desc *gpio_index;
+
+ int irq_a;
+ int irq_b;
+ int irq_index;
+
+ spinlock_t lock;
+
+ s64 count;
+ u64 ceiling;
+ bool enabled;
+ enum counter_count_direction direction;
+ enum gpio_qenc_function function;
+
+ int prev_a;
+ int prev_b;
+
+ bool index_enabled;
+
+ struct counter_signal signals[3];
+ struct counter_synapse synapses[3];
+ struct counter_count cnts;
+};
+
+/*
+ * Quadrature state table for X4 decoding.
+ * Rows = previous state (A<<1 | B), Columns = new state (A<<1 | B).
+ * Values: 0 = no change, +1 = forward, -1 = backward, 2 = error (skip).
+ */
+static const int quad_table[4][4] = {
+ /* 00 01 10 11 <- new */
+ /* 00 */ { 0, -1, 1, 2 },
+ /* 01 */ { 1, 0, 2, -1 },
+ /* 10 */ { -1, 2, 0, 1 },
+ /* 11 */ { 2, 1, -1, 0 },
+};
+
+static void gpio_qenc_update_count(struct gpio_qenc_priv *priv, int delta)
+{
+ s64 new_count;
+
+ if (!delta)
+ return;
+
+ new_count = priv->count + delta;
+
+ if (priv->ceiling) {
+ if (new_count < 0)
+ new_count = 0;
+ else if (new_count > (s64)priv->ceiling)
+ new_count = priv->ceiling;
+ }
+
+ priv->count = new_count;
+ priv->direction = (delta > 0) ? COUNTER_COUNT_DIRECTION_FORWARD
+ : COUNTER_COUNT_DIRECTION_BACKWARD;
+}
+
+static irqreturn_t gpio_qenc_a_isr(int irq, void *dev_id)
+{
+ struct counter_device *counter = dev_id;
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+ int a, b, prev_state, new_state, delta;
+
+ spin_lock_irqsave(&priv->lock, flags);
+
+ if (!priv->enabled)
+ goto out;
+
+ a = gpiod_get_value(priv->gpio_a);
+ b = gpiod_get_value(priv->gpio_b);
+
+ prev_state = (priv->prev_a << 1) | priv->prev_b;
+ new_state = (a << 1) | b;
+
+ switch (priv->function) {
+ case GPIO_QENC_FUNC_QUAD_X4:
+ delta = quad_table[prev_state][new_state];
+ if (delta == 2)
+ delta = 0;
+ gpio_qenc_update_count(priv, delta);
+ break;
+
+ case GPIO_QENC_FUNC_QUAD_X2:
+ delta = quad_table[prev_state][new_state];
+ if (delta == 2)
+ delta = 0;
+ gpio_qenc_update_count(priv, delta);
+ break;
+
+ case GPIO_QENC_FUNC_QUAD_X1:
+ if (!priv->prev_a && a) {
+ delta = b ? -1 : 1;
+ gpio_qenc_update_count(priv, delta);
+ }
+ break;
+
+ case GPIO_QENC_FUNC_PULSE_DIR:
+ if (!priv->prev_a && a) {
+ delta = b ? -1 : 1;
+ gpio_qenc_update_count(priv, delta);
+ }
+ break;
+ }
+
+ priv->prev_a = a;
+ priv->prev_b = b;
+
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ counter_push_event(counter, COUNTER_EVENT_CHANGE_OF_STATE, 0);
+
+ return IRQ_HANDLED;
+
+out:
+ spin_unlock_irqrestore(&priv->lock, flags);
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t gpio_qenc_b_isr(int irq, void *dev_id)
+{
+ struct counter_device *counter = dev_id;
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+ int a, b, prev_state, new_state, delta;
+
+ spin_lock_irqsave(&priv->lock, flags);
+
+ if (!priv->enabled)
+ goto out;
+
+ a = gpiod_get_value(priv->gpio_a);
+ b = gpiod_get_value(priv->gpio_b);
+
+ prev_state = (priv->prev_a << 1) | priv->prev_b;
+ new_state = (a << 1) | b;
+
+ switch (priv->function) {
+ case GPIO_QENC_FUNC_QUAD_X4:
+ delta = quad_table[prev_state][new_state];
+ if (delta == 2)
+ delta = 0;
+ gpio_qenc_update_count(priv, delta);
+ break;
+
+ case GPIO_QENC_FUNC_QUAD_X2:
+ /* X2: only A-channel edges update count */
+ break;
+
+ case GPIO_QENC_FUNC_QUAD_X1:
+ case GPIO_QENC_FUNC_PULSE_DIR:
+ break;
+ }
+
+ priv->prev_a = a;
+ priv->prev_b = b;
+
+ spin_unlock_irqrestore(&priv->lock, flags);
+ return IRQ_HANDLED;
+
+out:
+ spin_unlock_irqrestore(&priv->lock, flags);
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t gpio_qenc_index_isr(int irq, void *dev_id)
+{
+ struct counter_device *counter = dev_id;
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+
+ if (priv->enabled && priv->index_enabled)
+ priv->count = 0;
+
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ counter_push_event(counter, COUNTER_EVENT_INDEX, 0);
+
+ return IRQ_HANDLED;
+}
+
+static int gpio_qenc_count_read(struct counter_device *counter,
+ struct counter_count *count, u64 *val)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+ *val = (u64)priv->count;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ return 0;
+}
+
+static int gpio_qenc_count_write(struct counter_device *counter,
+ struct counter_count *count, const u64 val)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+
+ if (priv->ceiling && val > priv->ceiling) {
+ spin_unlock_irqrestore(&priv->lock, flags);
+ return -EINVAL;
+ }
+
+ priv->count = (s64)val;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ return 0;
+}
+
+static const enum counter_function gpio_qenc_functions[] = {
+ COUNTER_FUNCTION_QUADRATURE_X1_A,
+ COUNTER_FUNCTION_QUADRATURE_X2_A,
+ COUNTER_FUNCTION_QUADRATURE_X4,
+ COUNTER_FUNCTION_PULSE_DIRECTION,
+};
+
+static int gpio_qenc_function_read(struct counter_device *counter,
+ struct counter_count *count,
+ enum counter_function *function)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+
+ switch (priv->function) {
+ case GPIO_QENC_FUNC_QUAD_X1:
+ *function = COUNTER_FUNCTION_QUADRATURE_X1_A;
+ break;
+ case GPIO_QENC_FUNC_QUAD_X2:
+ *function = COUNTER_FUNCTION_QUADRATURE_X2_A;
+ break;
+ case GPIO_QENC_FUNC_QUAD_X4:
+ *function = COUNTER_FUNCTION_QUADRATURE_X4;
+ break;
+ case GPIO_QENC_FUNC_PULSE_DIR:
+ *function = COUNTER_FUNCTION_PULSE_DIRECTION;
+ break;
+ }
+
+ spin_unlock_irqrestore(&priv->lock, flags);
+ return 0;
+}
+
+static int gpio_qenc_function_write(struct counter_device *counter,
+ struct counter_count *count,
+ enum counter_function function)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+
+ switch (function) {
+ case COUNTER_FUNCTION_QUADRATURE_X1_A:
+ priv->function = GPIO_QENC_FUNC_QUAD_X1;
+ break;
+ case COUNTER_FUNCTION_QUADRATURE_X2_A:
+ priv->function = GPIO_QENC_FUNC_QUAD_X2;
+ break;
+ case COUNTER_FUNCTION_QUADRATURE_X4:
+ priv->function = GPIO_QENC_FUNC_QUAD_X4;
+ break;
+ case COUNTER_FUNCTION_PULSE_DIRECTION:
+ priv->function = GPIO_QENC_FUNC_PULSE_DIR;
+ break;
+ default:
+ spin_unlock_irqrestore(&priv->lock, flags);
+ return -EINVAL;
+ }
+
+ spin_unlock_irqrestore(&priv->lock, flags);
+ return 0;
+}
+
+static const enum counter_synapse_action gpio_qenc_synapse_actions[] = {
+ COUNTER_SYNAPSE_ACTION_BOTH_EDGES,
+ COUNTER_SYNAPSE_ACTION_RISING_EDGE,
+ COUNTER_SYNAPSE_ACTION_NONE,
+};
+
+static int gpio_qenc_action_read(struct counter_device *counter,
+ struct counter_count *count,
+ struct counter_synapse *synapse,
+ enum counter_synapse_action *action)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ enum gpio_qenc_signal_id signal_id = synapse->signal->id;
+
+ switch (priv->function) {
+ case GPIO_QENC_FUNC_QUAD_X4:
+ if (signal_id == GPIO_QENC_SIGNAL_A ||
+ signal_id == GPIO_QENC_SIGNAL_B)
+ *action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
+ else
+ *action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
+ return 0;
+
+ case GPIO_QENC_FUNC_QUAD_X2:
+ if (signal_id == GPIO_QENC_SIGNAL_A)
+ *action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
+ else if (signal_id == GPIO_QENC_SIGNAL_B)
+ *action = COUNTER_SYNAPSE_ACTION_NONE;
+ else
+ *action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
+ return 0;
+
+ case GPIO_QENC_FUNC_QUAD_X1:
+ if (signal_id == GPIO_QENC_SIGNAL_A)
+ *action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
+ else if (signal_id == GPIO_QENC_SIGNAL_B)
+ *action = COUNTER_SYNAPSE_ACTION_NONE;
+ else
+ *action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
+ return 0;
+
+ case GPIO_QENC_FUNC_PULSE_DIR:
+ if (signal_id == GPIO_QENC_SIGNAL_A)
+ *action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
+ else
+ *action = COUNTER_SYNAPSE_ACTION_NONE;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static int gpio_qenc_signal_read(struct counter_device *counter,
+ struct counter_signal *signal,
+ enum counter_signal_level *level)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ struct gpio_desc *gpio;
+ int ret;
+
+ switch (signal->id) {
+ case GPIO_QENC_SIGNAL_A:
+ gpio = priv->gpio_a;
+ break;
+ case GPIO_QENC_SIGNAL_B:
+ gpio = priv->gpio_b;
+ break;
+ case GPIO_QENC_SIGNAL_INDEX:
+ gpio = priv->gpio_index;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (!gpio)
+ return -EINVAL;
+
+ ret = gpiod_get_value(gpio);
+ if (ret < 0)
+ return ret;
+
+ *level = ret ? COUNTER_SIGNAL_LEVEL_HIGH : COUNTER_SIGNAL_LEVEL_LOW;
+ return 0;
+}
+
+static int gpio_qenc_events_configure(struct counter_device *counter)
+{
+ return 0;
+}
+
+static int gpio_qenc_watch_validate(struct counter_device *counter,
+ const struct counter_watch *watch)
+{
+ if (watch->channel != 0)
+ return -EINVAL;
+
+ switch (watch->event) {
+ case COUNTER_EVENT_CHANGE_OF_STATE:
+ case COUNTER_EVENT_INDEX:
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct counter_ops gpio_qenc_ops = {
+ .count_read = gpio_qenc_count_read,
+ .count_write = gpio_qenc_count_write,
+ .function_read = gpio_qenc_function_read,
+ .function_write = gpio_qenc_function_write,
+ .action_read = gpio_qenc_action_read,
+ .signal_read = gpio_qenc_signal_read,
+ .events_configure = gpio_qenc_events_configure,
+ .watch_validate = gpio_qenc_watch_validate,
+};
+
+static int gpio_qenc_ceiling_read(struct counter_device *counter,
+ struct counter_count *count, u64 *val)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+ *val = priv->ceiling;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ return 0;
+}
+
+static int gpio_qenc_ceiling_write(struct counter_device *counter,
+ struct counter_count *count, const u64 val)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+ priv->ceiling = val;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ return 0;
+}
+
+static int gpio_qenc_enable_read(struct counter_device *counter,
+ struct counter_count *count, u8 *enable)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+
+ *enable = priv->enabled;
+ return 0;
+}
+
+static int gpio_qenc_enable_write(struct counter_device *counter,
+ struct counter_count *count, u8 enable)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+
+ if (priv->enabled == !!enable) {
+ spin_unlock_irqrestore(&priv->lock, flags);
+ return 0;
+ }
+
+ if (enable) {
+ priv->enabled = true;
+ spin_unlock_irqrestore(&priv->lock, flags);
+ enable_irq(priv->irq_a);
+ enable_irq(priv->irq_b);
+ if (priv->irq_index)
+ enable_irq(priv->irq_index);
+ } else {
+ priv->enabled = false;
+ spin_unlock_irqrestore(&priv->lock, flags);
+ disable_irq(priv->irq_a);
+ disable_irq(priv->irq_b);
+ if (priv->irq_index)
+ disable_irq(priv->irq_index);
+ }
+
+ return 0;
+}
+
+static int gpio_qenc_direction_read(struct counter_device *counter,
+ struct counter_count *count, u32 *direction)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+ *direction = priv->direction;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ return 0;
+}
+
+static int gpio_qenc_index_enable_read(struct counter_device *counter,
+ struct counter_count *count, u8 *val)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+
+ *val = priv->index_enabled;
+ return 0;
+}
+
+static int gpio_qenc_index_enable_write(struct counter_device *counter,
+ struct counter_count *count, u8 val)
+{
+ struct gpio_qenc_priv *priv = counter_priv(counter);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+ priv->index_enabled = !!val;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ return 0;
+}
+
+static struct counter_comp gpio_qenc_count_ext[] = {
+ COUNTER_COMP_CEILING(gpio_qenc_ceiling_read, gpio_qenc_ceiling_write),
+ COUNTER_COMP_ENABLE(gpio_qenc_enable_read, gpio_qenc_enable_write),
+ COUNTER_COMP_DIRECTION(gpio_qenc_direction_read),
+ COUNTER_COMP_COUNT_BOOL("index_enabled",
+ gpio_qenc_index_enable_read,
+ gpio_qenc_index_enable_write),
+};
+
+static int gpio_qenc_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct counter_device *counter;
+ struct gpio_qenc_priv *priv;
+ bool has_index;
+ int num_signals;
+ int num_synapses;
+ int ret;
+
+ counter = devm_counter_alloc(dev, sizeof(*priv));
+ if (!counter)
+ return -ENOMEM;
+
+ priv = counter_priv(counter);
+ spin_lock_init(&priv->lock);
+
+ priv->gpio_a = devm_gpiod_get(dev, "encoder-a", GPIOD_IN);
+ if (IS_ERR(priv->gpio_a))
+ return dev_err_probe(dev, PTR_ERR(priv->gpio_a),
+ "failed to get encoder-a GPIO\n");
+
+ priv->gpio_b = devm_gpiod_get(dev, "encoder-b", GPIOD_IN);
+ if (IS_ERR(priv->gpio_b))
+ return dev_err_probe(dev, PTR_ERR(priv->gpio_b),
+ "failed to get encoder-b GPIO\n");
+
+ priv->gpio_index = devm_gpiod_get_optional(dev, "encoder-index",
+ GPIOD_IN);
+ if (IS_ERR(priv->gpio_index))
+ return dev_err_probe(dev, PTR_ERR(priv->gpio_index),
+ "failed to get encoder-index GPIO\n");
+
+ has_index = !!priv->gpio_index;
+
+ priv->irq_a = gpiod_to_irq(priv->gpio_a);
+ if (priv->irq_a < 0)
+ return dev_err_probe(dev, priv->irq_a,
+ "failed to get IRQ for encoder-a\n");
+
+ priv->irq_b = gpiod_to_irq(priv->gpio_b);
+ if (priv->irq_b < 0)
+ return dev_err_probe(dev, priv->irq_b,
+ "failed to get IRQ for encoder-b\n");
+
+ if (has_index) {
+ priv->irq_index = gpiod_to_irq(priv->gpio_index);
+ if (priv->irq_index < 0)
+ return dev_err_probe(dev, priv->irq_index,
+ "failed to get IRQ for encoder-index\n");
+ }
+
+ priv->prev_a = gpiod_get_value(priv->gpio_a);
+ priv->prev_b = gpiod_get_value(priv->gpio_b);
+
+ priv->function = GPIO_QENC_FUNC_QUAD_X4;
+ priv->direction = COUNTER_COUNT_DIRECTION_FORWARD;
+
+ num_signals = has_index ? 3 : 2;
+
+ priv->signals[GPIO_QENC_SIGNAL_A].id = GPIO_QENC_SIGNAL_A;
+ priv->signals[GPIO_QENC_SIGNAL_A].name = "Signal A";
+
+ priv->signals[GPIO_QENC_SIGNAL_B].id = GPIO_QENC_SIGNAL_B;
+ priv->signals[GPIO_QENC_SIGNAL_B].name = "Signal B";
+
+ if (has_index) {
+ priv->signals[GPIO_QENC_SIGNAL_INDEX].id =
+ GPIO_QENC_SIGNAL_INDEX;
+ priv->signals[GPIO_QENC_SIGNAL_INDEX].name = "Index";
+ }
+
+ num_synapses = num_signals;
+
+ priv->synapses[0].actions_list = gpio_qenc_synapse_actions;
+ priv->synapses[0].num_actions = ARRAY_SIZE(gpio_qenc_synapse_actions);
+ priv->synapses[0].signal = &priv->signals[GPIO_QENC_SIGNAL_A];
+
+ priv->synapses[1].actions_list = gpio_qenc_synapse_actions;
+ priv->synapses[1].num_actions = ARRAY_SIZE(gpio_qenc_synapse_actions);
+ priv->synapses[1].signal = &priv->signals[GPIO_QENC_SIGNAL_B];
+
+ if (has_index) {
+ priv->synapses[2].actions_list = gpio_qenc_synapse_actions;
+ priv->synapses[2].num_actions =
+ ARRAY_SIZE(gpio_qenc_synapse_actions);
+ priv->synapses[2].signal =
+ &priv->signals[GPIO_QENC_SIGNAL_INDEX];
+ }
+
+ priv->cnts.id = 0;
+ priv->cnts.name = "Position";
+ priv->cnts.functions_list = gpio_qenc_functions;
+ priv->cnts.num_functions = ARRAY_SIZE(gpio_qenc_functions);
+ priv->cnts.synapses = priv->synapses;
+ priv->cnts.num_synapses = num_synapses;
+ priv->cnts.ext = gpio_qenc_count_ext;
+ priv->cnts.num_ext = ARRAY_SIZE(gpio_qenc_count_ext);
+
+ counter->name = dev_name(dev);
+ counter->parent = dev;
+ counter->ops = &gpio_qenc_ops;
+ counter->signals = priv->signals;
+ counter->num_signals = num_signals;
+ counter->counts = &priv->cnts;
+ counter->num_counts = 1;
+
+ irq_set_status_flags(priv->irq_a, IRQ_NOAUTOEN);
+ ret = devm_request_irq(dev, priv->irq_a, gpio_qenc_a_isr,
+ IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+ "gpio-qenc-a", counter);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "failed to request IRQ for encoder-a\n");
+
+ irq_set_status_flags(priv->irq_b, IRQ_NOAUTOEN);
+ ret = devm_request_irq(dev, priv->irq_b, gpio_qenc_b_isr,
+ IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+ "gpio-qenc-b", counter);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "failed to request IRQ for encoder-b\n");
+
+ if (has_index) {
+ irq_set_status_flags(priv->irq_index, IRQ_NOAUTOEN);
+ ret = devm_request_irq(dev, priv->irq_index,
+ gpio_qenc_index_isr,
+ IRQF_TRIGGER_RISING,
+ "gpio-qenc-index", counter);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "failed to request IRQ for encoder-index\n");
+ }
+
+ ret = devm_counter_add(dev, counter);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "failed to add counter\n");
+
+ dev_info(dev, "GPIO quadrature encoder registered (signals: A, B%s)\n",
+ has_index ? ", Index" : "");
+
+ return 0;
+}
+
+static const struct of_device_id gpio_qenc_of_match[] = {
+ { .compatible = "gpio-quadrature-encoder" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, gpio_qenc_of_match);
+
+static struct platform_driver gpio_qenc_driver = {
+ .probe = gpio_qenc_probe,
+ .driver = {
+ .name = "gpio-quadrature-encoder",
+ .of_match_table = gpio_qenc_of_match,
+ },
+};
+module_platform_driver(gpio_qenc_driver);
+
+MODULE_ALIAS("platform:gpio-quadrature-encoder");
+MODULE_AUTHOR("Wadim Mueller <wafgo01@gmail.com>");
+MODULE_DESCRIPTION("GPIO-based quadrature encoder counter driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("COUNTER");
--
2.52.0
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