LXR linux/drivers/pps/clients/pps-gpio.c

   1/*
   2 * pps-gpio.c -- PPS client driver using GPIO
   3 *
   4 *
   5 * Copyright (C) 2010 Ricardo Martins <rasm@fe.up.pt>
   6 * Copyright (C) 2011 James Nuss <jamesnuss@nanometrics.ca>
   7 *
   8 *   This program is free software; you can redistribute it and/or modify
   9 *   it under the terms of the GNU General Public License as published by
  10 *   the Free Software Foundation; either version 2 of the License, or
  11 *   (at your option) any later version.
  12 *
  13 *   This program is distributed in the hope that it will be useful,
  14 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 *   GNU General Public License for more details.
  17 *
  18 *   You should have received a copy of the GNU General Public License
  19 *   along with this program; if not, write to the Free Software
  20 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23#define PPS_GPIO_NAME "pps-gpio"
  24#define pr_fmt(fmt) PPS_GPIO_NAME ": " fmt
  25
  26#include <linux/init.h>
  27#include <linux/kernel.h>
  28#include <linux/interrupt.h>
  29#include <linux/module.h>
  30#include <linux/platform_device.h>
  31#include <linux/slab.h>
  32#include <linux/pps_kernel.h>
  33#include <linux/pps-gpio.h>
  34#include <linux/gpio.h>
  35#include <linux/list.h>
  36#include <linux/of_device.h>
  37#include <linux/of_gpio.h>
  38
  39/* Info for each registered platform device */
  40struct pps_gpio_device_data {
  41        int irq;                        /* IRQ used as PPS source */
  42        struct pps_device *pps;         /* PPS source device */
  43        struct pps_source_info info;    /* PPS source information */
  44        bool assert_falling_edge;
  45        bool capture_clear;
  46        unsigned int gpio_pin;
  47};
  48
  49/*
  50 * Report the PPS event
  51 */
  52
  53static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
  54{
  55        const struct pps_gpio_device_data *info;
  56        struct pps_event_time ts;
  57        int rising_edge;
  58
  59        /* Get the time stamp first */
  60        pps_get_ts(&ts);
  61
  62        info = data;
  63
  64        rising_edge = gpio_get_value(info->gpio_pin);
  65        if ((rising_edge && !info->assert_falling_edge) ||
  66                        (!rising_edge && info->assert_falling_edge))
  67                pps_event(info->pps, &ts, PPS_CAPTUREASSERT, NULL);
  68        else if (info->capture_clear &&
  69                        ((rising_edge && info->assert_falling_edge) ||
  70                         (!rising_edge && !info->assert_falling_edge)))
  71                pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL);
  72
  73        return IRQ_HANDLED;
  74}
  75
  76static unsigned long
  77get_irqf_trigger_flags(const struct pps_gpio_device_data *data)
  78{
  79        unsigned long flags = data->assert_falling_edge ?
  80                IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
  81
  82        if (data->capture_clear) {
  83                flags |= ((flags & IRQF_TRIGGER_RISING) ?
  84                                IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
  85        }
  86
  87        return flags;
  88}
  89
  90static int pps_gpio_probe(struct platform_device *pdev)
  91{
  92        struct pps_gpio_device_data *data;
  93        const char *gpio_label;
  94        int ret;
  95        int pps_default_params;
  96        const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
  97        struct device_node *np = pdev->dev.of_node;
  98
  99        /* allocate space for device info */
 100        data = devm_kzalloc(&pdev->dev, sizeof(struct pps_gpio_device_data),
 101                        GFP_KERNEL);
 102        if (!data)
 103                return -ENOMEM;
 104
 105        if (pdata) {
 106                data->gpio_pin = pdata->gpio_pin;
 107                gpio_label = pdata->gpio_label;
 108
 109                data->assert_falling_edge = pdata->assert_falling_edge;
 110                data->capture_clear = pdata->capture_clear;
 111        } else {
 112                ret = of_get_gpio(np, 0);
 113                if (ret < 0) {
 114                        dev_err(&pdev->dev, "failed to get GPIO from device tree\n");
 115                        return ret;
 116                }
 117                data->gpio_pin = ret;
 118                gpio_label = PPS_GPIO_NAME;
 119
 120                if (of_get_property(np, "assert-falling-edge", NULL))
 121                        data->assert_falling_edge = true;
 122        }
 123
 124        /* GPIO setup */
 125        ret = devm_gpio_request(&pdev->dev, data->gpio_pin, gpio_label);
 126        if (ret) {
 127                dev_err(&pdev->dev, "failed to request GPIO %u\n",
 128                        data->gpio_pin);
 129                return ret;
 130        }
 131
 132        ret = gpio_direction_input(data->gpio_pin);
 133        if (ret) {
 134                dev_err(&pdev->dev, "failed to set pin direction\n");
 135                return -EINVAL;
 136        }
 137
 138        /* IRQ setup */
 139        ret = gpio_to_irq(data->gpio_pin);
 140        if (ret < 0) {
 141                dev_err(&pdev->dev, "failed to map GPIO to IRQ: %d\n", ret);
 142                return -EINVAL;
 143        }
 144        data->irq = ret;
 145
 146        /* initialize PPS specific parts of the bookkeeping data structure. */
 147        data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
 148                PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
 149        if (data->capture_clear)
 150                data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
 151                        PPS_ECHOCLEAR;
 152        data->info.owner = THIS_MODULE;
 153        snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
 154                 pdev->name, pdev->id);
 155
 156        /* register PPS source */
 157        pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
 158        if (data->capture_clear)
 159                pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
 160        data->pps = pps_register_source(&data->info, pps_default_params);
 161        if (data->pps == NULL) {
 162                dev_err(&pdev->dev, "failed to register IRQ %d as PPS source\n",
 163                        data->irq);
 164                return -EINVAL;
 165        }
 166
 167        /* register IRQ interrupt handler */
 168        ret = devm_request_irq(&pdev->dev, data->irq, pps_gpio_irq_handler,
 169                        get_irqf_trigger_flags(data), data->info.name, data);
 170        if (ret) {
 171                pps_unregister_source(data->pps);
 172                dev_err(&pdev->dev, "failed to acquire IRQ %d\n", data->irq);
 173                return -EINVAL;
 174        }
 175
 176        platform_set_drvdata(pdev, data);
 177        dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n",
 178                 data->irq);
 179
 180        return 0;
 181}
 182
 183static int pps_gpio_remove(struct platform_device *pdev)
 184{
 185        struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
 186
 187        pps_unregister_source(data->pps);
 188        dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq);
 189        return 0;
 190}
 191
 192static const struct of_device_id pps_gpio_dt_ids[] = {
 193        { .compatible = "pps-gpio", },
 194        { /* sentinel */ }
 195};
 196MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
 197
 198static struct platform_driver pps_gpio_driver = {
 199        .probe          = pps_gpio_probe,
 200        .remove         = pps_gpio_remove,
 201        .driver         = {
 202                .name   = PPS_GPIO_NAME,
 203                .of_match_table = pps_gpio_dt_ids,
 204        },
 205};
 206
 207module_platform_driver(pps_gpio_driver);
 208MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
 209MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
 210MODULE_DESCRIPTION("Use GPIO pin as PPS source");
 211MODULE_LICENSE("GPL");
 212MODULE_VERSION("1.0.0");
 213