diff options
Diffstat (limited to 'drivers/pps/clients/pps-gpio.c')
| -rw-r--r-- | drivers/pps/clients/pps-gpio.c | 227 |
1 files changed, 227 insertions, 0 deletions
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"); |