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 */
  40 struct 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
  53 static 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
  76 static unsigned long
  77 get_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
  90 static 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
 183 static 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
 192 static const struct of_device_id pps_gpio_dt_ids[] = {
 193         { .compatible = "pps-gpio", },
 194         { /* sentinel */ }
 195 };
 196 MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
 197
 198 static 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
 207 module_platform_driver(pps_gpio_driver);
 208 MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
 209 MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
 210 MODULE_DESCRIPTION("Use GPIO pin as PPS source");
 211 MODULE_LICENSE("GPL");
 212 MODULE_VERSION("1.0.0");