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Subject[RFC 4/4] iio: trigger: add GPIO trigger
Date
GPIOs can be used to generate triggers for any IIO device.
Introduce generic GPIO trigger driver. It offers some options
to tune polarity (e.g. rising/falling edge), and label so trigger
name may be customized.
By default, gpio triggers will be named gpiotrigX, where X is gpio
number as returned by desc_to_gpio() call.
Rising edge is selected if polarity isn't set.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
drivers/iio/trigger/Kconfig | 9 +++
drivers/iio/trigger/Makefile | 1 +
drivers/iio/trigger/iio-trig-gpio.c | 112 ++++++++++++++++++++++++++++++++++++
3 files changed, 122 insertions(+)
create mode 100644 drivers/iio/trigger/iio-trig-gpio.c

diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
index e4d4e63..54b6706 100644
--- a/drivers/iio/trigger/Kconfig
+++ b/drivers/iio/trigger/Kconfig
@@ -5,6 +5,15 @@

menu "Triggers - standalone"

+config IIO_GPIO_TRIGGER
+ tristate "Generic GPIO trigger"
+ help
+ Provides support for a GPIO based IIO trigger, when trigger
+ source has been connected to a GPIO line.
+
+ To compile this driver as a module, choose M here: the
+ module will be called iio-gpio-trigger.
+
config IIO_HRTIMER_TRIGGER
tristate "High resolution timer trigger"
depends on IIO_SW_TRIGGER
diff --git a/drivers/iio/trigger/Makefile b/drivers/iio/trigger/Makefile
index 5c4ecd3..a984668 100644
--- a/drivers/iio/trigger/Makefile
+++ b/drivers/iio/trigger/Makefile
@@ -4,6 +4,7 @@

# When adding new entries keep the list in alphabetical order

+obj-$(CONFIG_IIO_GPIO_TRIGGER) += iio-trig-gpio.o
obj-$(CONFIG_IIO_HRTIMER_TRIGGER) += iio-trig-hrtimer.o
obj-$(CONFIG_IIO_INTERRUPT_TRIGGER) += iio-trig-interrupt.o
obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
diff --git a/drivers/iio/trigger/iio-trig-gpio.c b/drivers/iio/trigger/iio-trig-gpio.c
new file mode 100644
index 0000000..4b48df0
--- /dev/null
+++ b/drivers/iio/trigger/iio-trig-gpio.c
@@ -0,0 +1,112 @@
+/*
+ * Industrial I/O - GPIO based trigger support
+ *
+ * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
+ * Author: Fabrice Gasnier <fabrice.gasnier@st.com>.
+ *
+ * License type: GPLv2
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+static const struct iio_trigger_ops iio_gpio_trigger_ops = {
+ .owner = THIS_MODULE,
+};
+
+static int iio_gpio_trigger_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct gpio_desc *gpio;
+ char name[16];
+ const char *label = NULL;
+ struct iio_trigger *trig;
+ unsigned long irqflags = IRQF_SHARED;
+ int irq, ret;
+
+ gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_IN);
+ if (IS_ERR(gpio)) {
+ if (PTR_ERR(gpio) != -EPROBE_DEFER)
+ dev_err(&pdev->dev, "gpio get failed (%ld)\n",
+ PTR_ERR(gpio));
+ return PTR_ERR(gpio);
+ }
+
+ if (of_property_read_string(np, "label", &label))
+ snprintf(name, sizeof(name), "gpiotrig%d", desc_to_gpio(gpio));
+
+ if (of_property_read_bool(np, "gpio-trigger-rising-edge"))
+ irqflags |= IRQF_TRIGGER_RISING;
+
+ if (of_property_read_bool(np, "gpio-trigger-falling-edge"))
+ irqflags |= IRQF_TRIGGER_FALLING;
+
+ /* Default to rising edge */
+ if (!(irqflags & IRQF_TRIGGER_MASK))
+ irqflags |= IRQF_TRIGGER_RISING;
+
+ trig = devm_iio_trigger_alloc(&pdev->dev, "%s", label ? label : name);
+ if (!trig)
+ return -ENOMEM;
+ trig->dev.parent = &pdev->dev;
+ trig->dev.of_node = pdev->dev.of_node;
+ trig->ops = &iio_gpio_trigger_ops;
+
+ irq = gpiod_to_irq(gpio);
+ if (irq < 0) {
+ dev_err(&pdev->dev, "gpio %d to irq failed (%d)\n",
+ desc_to_gpio(gpio), irq);
+ return irq;
+ }
+
+ ret = devm_request_irq(&pdev->dev, irq,
+ iio_trigger_generic_data_rdy_poll, irqflags,
+ trig->name, trig);
+ if (ret) {
+ dev_err(&pdev->dev, "request IRQ %d failed\n", irq);
+ return ret;
+ }
+
+ ret = devm_iio_trigger_register(&pdev->dev, trig);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id iio_gpio_trigger_of_match[] = {
+ { .compatible = "iio-gpio-trigger" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, iio_gpio_trigger_of_match);
+#endif
+
+static struct platform_driver iio_gpio_trigger_driver = {
+ .probe = iio_gpio_trigger_probe,
+ .driver = {
+ .name = "iio-gpio-trigger",
+ .of_match_table = of_match_ptr(iio_gpio_trigger_of_match),
+ },
+};
+module_platform_driver(iio_gpio_trigger_driver);
+
+MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
+MODULE_DESCRIPTION("GPIO trigger for iio subsystem");
+MODULE_LICENSE("GPL v2");
--
1.9.1
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