From 25cea963bfec296362318ff2a243d5970b909ce3 Mon Sep 17 00:00:00 2001 From: James Nuss Date: Thu, 25 Aug 2011 09:47:54 +1000 Subject: [PATCH] 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 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 Cc: Ricardo Martins Acked-by: Rodolfo Giometti Cc: Ricardo Martins Cc: Alexander Gordeev Cc: Igor Plyatov Signed-off-by: Andrew Morton --- 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(+) 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 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..93f1be06892c --- /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 + * Copyright (C) 2011 James Nuss + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* 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 "); +MODULE_AUTHOR("James Nuss "); +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 000000000000..0035abe41b9a --- /dev/null +++ b/include/linux/pps-gpio.h @@ -0,0 +1,32 @@ +/* + * pps-gpio.h -- PPS client for GPIOs + * + * + * Copyright (C) 2011 James Nuss + * + * 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 -- 2.39.5