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
  37 /* Info for each registered platform device */
  38 struct pps_gpio_device_data {
  39         int irq;                        /* IRQ used as PPS source */
  40         struct pps_device *pps;         /* PPS source device */
  41         struct pps_source_info info;    /* PPS source information */
  42         const struct pps_gpio_platform_data *pdata;
  43 };
  44
  45 /*
  46  * Report the PPS event
  47  */
  48
  49 static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
  50 {
  51         const struct pps_gpio_device_data *info;
  52         struct pps_event_time ts;
  53         int rising_edge;
  54
  55         /* Get the time stamp first */
  56         pps_get_ts(&ts);
  57
  58         info = data;
  59
  60         rising_edge = gpio_get_value(info->pdata->gpio_pin);
  61         if ((rising_edge && !info->pdata->assert_falling_edge) ||
  62                         (!rising_edge && info->pdata->assert_falling_edge))
  63                 pps_event(info->pps, &ts, PPS_CAPTUREASSERT, NULL);
  64         else if (info->pdata->capture_clear &&
  65                         ((rising_edge && info->pdata->assert_falling_edge) ||
  66                          (!rising_edge && !info->pdata->assert_falling_edge)))
  67                 pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL);
  68
  69         return IRQ_HANDLED;
  70 }
  71
  72 static int pps_gpio_setup(struct platform_device *pdev)
  73 {
  74         int ret;
  75         const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
  76
  77         ret = gpio_request(pdata->gpio_pin, pdata->gpio_label);
  78         if (ret) {
  79                 pr_warning("failed to request GPIO %u\n", pdata->gpio_pin);
  80                 return -EINVAL;
  81         }
  82
  83         ret = gpio_direction_input(pdata->gpio_pin);
  84         if (ret) {
  85                 pr_warning("failed to set pin direction\n");
  86                 gpio_free(pdata->gpio_pin);
  87                 return -EINVAL;
  88         }
  89
  90         return 0;
  91 }
  92
  93 static unsigned long
  94 get_irqf_trigger_flags(const struct pps_gpio_platform_data *pdata)
  95 {
  96         unsigned long flags = pdata->assert_falling_edge ?
  97                 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
  98
  99         if (pdata->capture_clear) {
 100                 flags |= ((flags & IRQF_TRIGGER_RISING) ?
 101                                 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
 102         }
 103
 104         return flags;
 105 }
 106
 107 static int pps_gpio_probe(struct platform_device *pdev)
 108 {
 109         struct pps_gpio_device_data *data;
 110         int irq;
 111         int ret;
 112         int err;
 113         int pps_default_params;
 114         const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
 115
 116
 117         /* GPIO setup */
 118         ret = pps_gpio_setup(pdev);
 119         if (ret)
 120                 return -EINVAL;
 121
 122         /* IRQ setup */
 123         irq = gpio_to_irq(pdata->gpio_pin);
 124         if (irq < 0) {
 125                 pr_err("failed to map GPIO to IRQ: %d\n", irq);
 126                 err = -EINVAL;
 127                 goto return_error;
 128         }
 129
 130         /* allocate space for device info */
 131         data = kzalloc(sizeof(struct pps_gpio_device_data), GFP_KERNEL);
 132         if (data == NULL) {
 133                 err = -ENOMEM;
 134                 goto return_error;
 135         }
 136
 137         /* initialize PPS specific parts of the bookkeeping data structure. */
 138         data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
 139                 PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
 140         if (pdata->capture_clear)
 141                 data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
 142                         PPS_ECHOCLEAR;
 143         data->info.owner = THIS_MODULE;
 144         snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
 145                  pdev->name, pdev->id);
 146
 147         /* register PPS source */
 148         pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
 149         if (pdata->capture_clear)
 150                 pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
 151         data->pps = pps_register_source(&data->info, pps_default_params);
 152         if (data->pps == NULL) {
 153                 kfree(data);
 154                 pr_err("failed to register IRQ %d as PPS source\n", irq);
 155                 err = -EINVAL;
 156                 goto return_error;
 157         }
 158
 159         data->irq = irq;
 160         data->pdata = pdata;
 161
 162         /* register IRQ interrupt handler */
 163         ret = request_irq(irq, pps_gpio_irq_handler,
 164                         get_irqf_trigger_flags(pdata), data->info.name, data);
 165         if (ret) {
 166                 pps_unregister_source(data->pps);
 167                 kfree(data);
 168                 pr_err("failed to acquire IRQ %d\n", irq);
 169                 err = -EINVAL;
 170                 goto return_error;
 171         }
 172
 173         platform_set_drvdata(pdev, data);
 174         dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n", irq);
 175
 176         return 0;
 177
 178 return_error:
 179         gpio_free(pdata->gpio_pin);
 180         return err;
 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         const struct pps_gpio_platform_data *pdata = data->pdata;
 187
 188         platform_set_drvdata(pdev, NULL);
 189         free_irq(data->irq, data);
 190         gpio_free(pdata->gpio_pin);
 191         pps_unregister_source(data->pps);
 192         pr_info("removed IRQ %d as PPS source\n", data->irq);
 193         kfree(data);
 194         return 0;
 195 }
 196
 197 static struct platform_driver pps_gpio_driver = {
 198         .probe          = pps_gpio_probe,
 199         .remove         = pps_gpio_remove,
 200         .driver         = {
 201                 .name   = PPS_GPIO_NAME,
 202                 .owner  = THIS_MODULE
 203         },
 204 };
 205
 206 static int __init pps_gpio_init(void)
 207 {
 208         int ret = platform_driver_register(&pps_gpio_driver);
 209         if (ret < 0)
 210                 pr_err("failed to register platform driver\n");
 211         return ret;
 212 }
 213
 214 static void __exit pps_gpio_exit(void)
 215 {
 216         platform_driver_unregister(&pps_gpio_driver);
 217         pr_debug("unregistered platform driver\n");
 218 }
 219
 220 module_init(pps_gpio_init);
 221 module_exit(pps_gpio_exit);
 222
 223 MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
 224 MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
 225 MODULE_DESCRIPTION("Use GPIO pin as PPS source");
 226 MODULE_LICENSE("GPL");
 227 MODULE_VERSION("1.0.0");