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Subject[PATCH v4 2/2] pps: new client driver using GPIO
Date
This client driver allows you to use a GPIO pin as a source for PPS
signals. Platform data [1] are used to specify the GPIO pin number, label,
assert event edge type, and whether clear events are captured.

This driver is based on the work by Ricardo Martins <rasm@fe.up.pt> who
submitted an initial implementation [2] of a PPS IRQ client driver to
the linuxpps mailing-list on Dec 3 2010.

[1] include/linux/pps-gpio.h
[2] http://ml.enneenne.com/pipermail/linuxpps/2010-December/004155.html

Signed-off-by: James Nuss <jamesnuss@nanometrics.ca>
CC: Ricardo Martins <rasm@fe.up.pt>
Acked-by: Rodolfo Giometti <giometti@linux.it>
---
drivers/pps/clients/Kconfig | 9 ++
drivers/pps/clients/Makefile | 1 +
drivers/pps/clients/pps-gpio.c | 227 ++++++++++++++++++++++++++++++++++++++++
include/linux/pps-gpio.h | 32 ++++++
4 files changed, 269 insertions(+), 0 deletions(-)
create mode 100644 drivers/pps/clients/pps-gpio.c
create mode 100644 include/linux/pps-gpio.h
diff --git a/drivers/pps/clients/Kconfig b/drivers/pps/clients/Kconfig
index 8520a7f..c2e0f1e 100644
--- a/drivers/pps/clients/Kconfig
+++ b/drivers/pps/clients/Kconfig
@@ -29,4 +29,13 @@ config PPS_CLIENT_PARPORT
If you say yes here you get support for a PPS source connected
with the interrupt pin of your parallel port.

+config PPS_CLIENT_GPIO
+ tristate "PPS client using GPIO"
+ depends on PPS
+ help
+ If you say yes here you get support for a PPS source using
+ GPIO. To be useful you must also register a platform device
+ specifying the GPIO pin and other options, usually in your board
+ setup.
+
endif
diff --git a/drivers/pps/clients/Makefile b/drivers/pps/clients/Makefile
index 4feb7e9..a461d15 100644
--- a/drivers/pps/clients/Makefile
+++ b/drivers/pps/clients/Makefile
@@ -5,5 +5,6 @@
obj-$(CONFIG_PPS_CLIENT_KTIMER) += pps-ktimer.o
obj-$(CONFIG_PPS_CLIENT_LDISC) += pps-ldisc.o
obj-$(CONFIG_PPS_CLIENT_PARPORT) += pps_parport.o
+obj-$(CONFIG_PPS_CLIENT_GPIO) += pps-gpio.o

ccflags-$(CONFIG_PPS_DEBUG) := -DDEBUG
diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c
new file mode 100644
index 0000000..93f1be0
--- /dev/null
+++ b/drivers/pps/clients/pps-gpio.c
@@ -0,0 +1,227 @@
+/*
+ * pps-gpio.c -- PPS client driver using GPIO
+ *
+ *
+ * Copyright (C) 2010 Ricardo Martins <rasm@fe.up.pt>
+ * Copyright (C) 2011 James Nuss <jamesnuss@nanometrics.ca>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#define PPS_GPIO_NAME "pps-gpio"
+#define pr_fmt(fmt) PPS_GPIO_NAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/pps_kernel.h>
+#include <linux/pps-gpio.h>
+#include <linux/gpio.h>
+#include <linux/list.h>
+
+/* Info for each registered platform device */
+struct pps_gpio_device_data {
+ int irq; /* IRQ used as PPS source */
+ struct pps_device *pps; /* PPS source device */
+ struct pps_source_info info; /* PPS source information */
+ const struct pps_gpio_platform_data *pdata;
+};
+
+/*
+ * Report the PPS event
+ */
+
+static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
+{
+ const struct pps_gpio_device_data *info;
+ struct pps_event_time ts;
+ int rising_edge;
+
+ /* Get the time stamp first */
+ pps_get_ts(&ts);
+
+ info = (const struct pps_gpio_device_data *)data;
+
+ rising_edge = gpio_get_value(info->pdata->gpio_pin);
+ if ((rising_edge && !info->pdata->assert_falling_edge) ||
+ (!rising_edge && info->pdata->assert_falling_edge))
+ pps_event(info->pps, &ts, PPS_CAPTUREASSERT, NULL);
+ else if (info->pdata->capture_clear &&
+ ((rising_edge && info->pdata->assert_falling_edge) ||
+ (!rising_edge && !info->pdata->assert_falling_edge)))
+ pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL);
+
+ return IRQ_HANDLED;
+}
+
+static int pps_gpio_setup(struct platform_device *pdev)
+{
+ int ret;
+ const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
+
+ ret = gpio_request(pdata->gpio_pin, pdata->gpio_label);
+ if (ret) {
+ pr_warning("failed to request GPIO %u\n", pdata->gpio_pin);
+ return -EINVAL;
+ }
+
+ ret = gpio_direction_input(pdata->gpio_pin);
+ if (ret) {
+ pr_warning("failed to set pin direction\n");
+ gpio_free(pdata->gpio_pin);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static unsigned long
+get_irqf_trigger_flags(const struct pps_gpio_platform_data *pdata)
+{
+ unsigned long flags = pdata->assert_falling_edge ?
+ IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
+
+ if (pdata->capture_clear) {
+ flags |= ((flags & IRQF_TRIGGER_RISING) ?
+ IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
+ }
+
+ return flags;
+}
+
+static int pps_gpio_probe(struct platform_device *pdev)
+{
+ struct pps_gpio_device_data *data;
+ int irq;
+ int ret;
+ int err;
+ int pps_default_params;
+ const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
+
+
+ /* GPIO setup */
+ ret = pps_gpio_setup(pdev);
+ if (ret)
+ return -EINVAL;
+
+ /* IRQ setup */
+ irq = gpio_to_irq(pdata->gpio_pin);
+ if (irq < 0) {
+ pr_err("failed to map GPIO to IRQ: %d\n", irq);
+ err = -EINVAL;
+ goto return_error;
+ }
+
+ /* allocate space for device info */
+ data = kzalloc(sizeof(struct pps_gpio_device_data), GFP_KERNEL);
+ if (data == NULL) {
+ err = -ENOMEM;
+ goto return_error;
+ }
+
+ /* initialize PPS specific parts of the bookkeeping data structure. */
+ data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
+ PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
+ if (pdata->capture_clear)
+ data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
+ PPS_ECHOCLEAR;
+ data->info.owner = THIS_MODULE;
+ snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
+ pdev->name, pdev->id);
+
+ /* register PPS source */
+ pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
+ if (pdata->capture_clear)
+ pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
+ data->pps = pps_register_source(&data->info, pps_default_params);
+ if (data->pps == NULL) {
+ kfree(data);
+ pr_err("failed to register IRQ %d as PPS source\n", irq);
+ err = -EINVAL;
+ goto return_error;
+ }
+
+ data->irq = irq;
+ data->pdata = pdata;
+
+ /* register IRQ interrupt handler */
+ ret = request_irq(irq, pps_gpio_irq_handler,
+ get_irqf_trigger_flags(pdata), data->info.name, data);
+ if (ret) {
+ pps_unregister_source(data->pps);
+ kfree(data);
+ pr_err("failed to acquire IRQ %d\n", irq);
+ err = -EINVAL;
+ goto return_error;
+ }
+
+ platform_set_drvdata(pdev, data);
+ dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n", irq);
+
+ return 0;
+
+return_error:
+ gpio_free(pdata->gpio_pin);
+ return err;
+}
+
+static int pps_gpio_remove(struct platform_device *pdev)
+{
+ struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
+ const struct pps_gpio_platform_data *pdata = data->pdata;
+
+ platform_set_drvdata(pdev, NULL);
+ free_irq(data->irq, data);
+ gpio_free(pdata->gpio_pin);
+ pps_unregister_source(data->pps);
+ pr_info("removed IRQ %d as PPS source\n", data->irq);
+ kfree(data);
+ return 0;
+}
+
+static struct platform_driver pps_gpio_driver = {
+ .probe = pps_gpio_probe,
+ .remove = __devexit_p(pps_gpio_remove),
+ .driver = {
+ .name = PPS_GPIO_NAME,
+ .owner = THIS_MODULE
+ },
+};
+
+static int __init pps_gpio_init(void)
+{
+ int ret = platform_driver_register(&pps_gpio_driver);
+ if (ret < 0)
+ pr_err("failed to register platform driver\n");
+ return ret;
+}
+
+static void __exit pps_gpio_exit(void)
+{
+ platform_driver_unregister(&pps_gpio_driver);
+ pr_debug("unregistered platform driver\n");
+}
+
+module_init(pps_gpio_init);
+module_exit(pps_gpio_exit);
+
+MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
+MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
+MODULE_DESCRIPTION("Use GPIO pin as PPS source");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.0.0");
diff --git a/include/linux/pps-gpio.h b/include/linux/pps-gpio.h
new file mode 100644
index 0000000..0035abe
--- /dev/null
+++ b/include/linux/pps-gpio.h
@@ -0,0 +1,32 @@
+/*
+ * pps-gpio.h -- PPS client for GPIOs
+ *
+ *
+ * Copyright (C) 2011 James Nuss <jamesnuss@nanometrics.ca>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef _PPS_GPIO_H
+#define _PPS_GPIO_H
+
+struct pps_gpio_platform_data {
+ bool assert_falling_edge;
+ bool capture_clear;
+ unsigned int gpio_pin;
+ const char *gpio_label;
+};
+
+#endif
--
1.7.1


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