3 files changed, 237 insertions, 0 deletions

diff --git a/drivers/pps/clients/Kconfig b/drivers/pps/clients/Kconfig
index 8520a7f4dd62..c2e0f1e97bcd 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 4feb7e9e71ee..a461d15f4a2e 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 000000000000..655055545479
--- /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 = 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");