diff options
Diffstat (limited to 'drivers/pps/clients/pps-gpio.c')
| -rw-r--r-- | drivers/pps/clients/pps-gpio.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c new file mode 100644 index 000000000..333ad7d5b --- /dev/null +++ b/drivers/pps/clients/pps-gpio.c @@ -0,0 +1,212 @@ +/* + * 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> +#include <linux/of_device.h> +#include <linux/of_gpio.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 */ + bool assert_falling_edge; + bool capture_clear; + unsigned int gpio_pin; +}; + +/* + * 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->gpio_pin); + if ((rising_edge && !info->assert_falling_edge) || + (!rising_edge && info->assert_falling_edge)) + pps_event(info->pps, &ts, PPS_CAPTUREASSERT, NULL); + else if (info->capture_clear && + ((rising_edge && info->assert_falling_edge) || + (!rising_edge && !info->assert_falling_edge))) + pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL); + + return IRQ_HANDLED; +} + +static unsigned long +get_irqf_trigger_flags(const struct pps_gpio_device_data *data) +{ + unsigned long flags = data->assert_falling_edge ? + IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING; + + if (data->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; + const char *gpio_label; + int ret; + int pps_default_params; + const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data; + struct device_node *np = pdev->dev.of_node; + + /* allocate space for device info */ + data = devm_kzalloc(&pdev->dev, sizeof(struct pps_gpio_device_data), + GFP_KERNEL); + if (!data) + return -ENOMEM; + + if (pdata) { + data->gpio_pin = pdata->gpio_pin; + gpio_label = pdata->gpio_label; + + data->assert_falling_edge = pdata->assert_falling_edge; + data->capture_clear = pdata->capture_clear; + } else { + ret = of_get_gpio(np, 0); + if (ret < 0) { + dev_err(&pdev->dev, "failed to get GPIO from device tree\n"); + return ret; + } + data->gpio_pin = ret; + gpio_label = PPS_GPIO_NAME; + + if (of_get_property(np, "assert-falling-edge", NULL)) + data->assert_falling_edge = true; + } + + /* GPIO setup */ + ret = devm_gpio_request(&pdev->dev, data->gpio_pin, gpio_label); + if (ret) { + dev_err(&pdev->dev, "failed to request GPIO %u\n", + data->gpio_pin); + return ret; + } + + ret = gpio_direction_input(data->gpio_pin); + if (ret) { + dev_err(&pdev->dev, "failed to set pin direction\n"); + return -EINVAL; + } + + /* IRQ setup */ + ret = gpio_to_irq(data->gpio_pin); + if (ret < 0) { + dev_err(&pdev->dev, "failed to map GPIO to IRQ: %d\n", ret); + return -EINVAL; + } + data->irq = ret; + + /* initialize PPS specific parts of the bookkeeping data structure. */ + data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT | + PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC; + if (data->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 (data->capture_clear) + pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR; + data->pps = pps_register_source(&data->info, pps_default_params); + if (data->pps == NULL) { + dev_err(&pdev->dev, "failed to register IRQ %d as PPS source\n", + data->irq); + return -EINVAL; + } + + /* register IRQ interrupt handler */ + ret = devm_request_irq(&pdev->dev, data->irq, pps_gpio_irq_handler, + get_irqf_trigger_flags(data), data->info.name, data); + if (ret) { + pps_unregister_source(data->pps); + dev_err(&pdev->dev, "failed to acquire IRQ %d\n", data->irq); + return -EINVAL; + } + + platform_set_drvdata(pdev, data); + dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n", + data->irq); + + return 0; +} + +static int pps_gpio_remove(struct platform_device *pdev) +{ + struct pps_gpio_device_data *data = platform_get_drvdata(pdev); + + pps_unregister_source(data->pps); + dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq); + return 0; +} + +static const struct of_device_id pps_gpio_dt_ids[] = { + { .compatible = "pps-gpio", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids); + +static struct platform_driver pps_gpio_driver = { + .probe = pps_gpio_probe, + .remove = pps_gpio_remove, + .driver = { + .name = PPS_GPIO_NAME, + .of_match_table = pps_gpio_dt_ids, + }, +}; + +module_platform_driver(pps_gpio_driver); +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"); |