drivers/pps/clients/pps-gpio.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * pps-gpio.c -- PPS client driver using GPIO
   4  *
   5  * Copyright (C) 2010 Ricardo Martins <rasm@fe.up.pt>
   6  * Copyright (C) 2011 James Nuss <jamesnuss@nanometrics.ca>
   7  */
   8
   9 #define PPS_GPIO_NAME "pps-gpio"
  10 #define pr_fmt(fmt) PPS_GPIO_NAME ": " fmt
  11
  12 #include <linux/init.h>
  13 #include <linux/kernel.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/mod_devicetable.h>
  16 #include <linux/module.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/slab.h>
  19 #include <linux/pps_kernel.h>
  20 #include <linux/gpio/consumer.h>
  21 #include <linux/list.h>
  22 #include <linux/property.h>
  23 #include <linux/timer.h>
  24 #include <linux/jiffies.h>
  25
  26 /* Info for each registered platform device */
  27 struct pps_gpio_device_data {
  28         int irq;                        /* IRQ used as PPS source */
  29         struct pps_device *pps;         /* PPS source device */
  30         struct pps_source_info info;    /* PPS source information */
  31         struct gpio_desc *gpio_pin;     /* GPIO port descriptors */
  32         struct gpio_desc *echo_pin;
  33         struct timer_list echo_timer;   /* timer to reset echo active state */
  34         bool assert_falling_edge;
  35         bool capture_clear;
  36         unsigned int echo_active_ms;    /* PPS echo active duration */
  37         unsigned long echo_timeout;     /* timer timeout value in jiffies */
  38 };
  39
  40 /*
  41  * Report the PPS event
  42  */
  43
  44 static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
  45 {
  46         const struct pps_gpio_device_data *info;
  47         struct pps_event_time ts;
  48         int rising_edge;
  49
  50         /* Get the time stamp first */
  51         pps_get_ts(&ts);
  52
  53         info = data;
  54
  55         rising_edge = gpiod_get_value(info->gpio_pin);
  56         if ((rising_edge && !info->assert_falling_edge) ||
  57                         (!rising_edge && info->assert_falling_edge))
  58                 pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
  59         else if (info->capture_clear &&
  60                         ((rising_edge && info->assert_falling_edge) ||
  61                         (!rising_edge && !info->assert_falling_edge)))
  62                 pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
  63
  64         return IRQ_HANDLED;
  65 }
  66
  67 /* This function will only be called when an ECHO GPIO is defined */
  68 static void pps_gpio_echo(struct pps_device *pps, int event, void *data)
  69 {
  70         /* add_timer() needs to write into info->echo_timer */
  71         struct pps_gpio_device_data *info = data;
  72
  73         switch (event) {
  74         case PPS_CAPTUREASSERT:
  75                 if (pps->params.mode & PPS_ECHOASSERT)
  76                         gpiod_set_value(info->echo_pin, 1);
  77                 break;
  78
  79         case PPS_CAPTURECLEAR:
  80                 if (pps->params.mode & PPS_ECHOCLEAR)
  81                         gpiod_set_value(info->echo_pin, 1);
  82                 break;
  83         }
  84
  85         /* fire the timer */
  86         if (info->pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) {
  87                 info->echo_timer.expires = jiffies + info->echo_timeout;
  88                 add_timer(&info->echo_timer);
  89         }
  90 }
  91
  92 /* Timer callback to reset the echo pin to the inactive state */
  93 static void pps_gpio_echo_timer_callback(struct timer_list *t)
  94 {
  95         const struct pps_gpio_device_data *info;
  96
  97         info = from_timer(info, t, echo_timer);
  98
  99         gpiod_set_value(info->echo_pin, 0);
 100 }
 101
 102 static int pps_gpio_setup(struct device *dev)
 103 {
 104         struct pps_gpio_device_data *data = dev_get_drvdata(dev);
 105         int ret;
 106         u32 value;
 107
 108         data->gpio_pin = devm_gpiod_get(dev, NULL, GPIOD_IN);
 109         if (IS_ERR(data->gpio_pin))
 110                 return dev_err_probe(dev, PTR_ERR(data->gpio_pin),
 111                                      "failed to request PPS GPIO\n");
 112
 113         data->assert_falling_edge =
 114                 device_property_read_bool(dev, "assert-falling-edge");
 115
 116         data->echo_pin = devm_gpiod_get_optional(dev, "echo", GPIOD_OUT_LOW);
 117         if (IS_ERR(data->echo_pin))
 118                 return dev_err_probe(dev, PTR_ERR(data->echo_pin),
 119                                      "failed to request ECHO GPIO\n");
 120
 121         if (!data->echo_pin)
 122                 return 0;
 123
 124         ret = device_property_read_u32(dev, "echo-active-ms", &value);
 125         if (ret) {
 126                 dev_err(dev, "failed to get echo-active-ms from FW\n");
 127                 return ret;
 128         }
 129
 130         /* sanity check on echo_active_ms */
 131         if (!value || value > 999) {
 132                 dev_err(dev, "echo-active-ms: %u - bad value from FW\n", value);
 133                 return -EINVAL;
 134         }
 135
 136         data->echo_active_ms = value;
 137
 138         return 0;
 139 }
 140
 141 static unsigned long
 142 get_irqf_trigger_flags(const struct pps_gpio_device_data *data)
 143 {
 144         unsigned long flags = data->assert_falling_edge ?
 145                 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
 146
 147         if (data->capture_clear) {
 148                 flags |= ((flags & IRQF_TRIGGER_RISING) ?
 149                                 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
 150         }
 151
 152         return flags;
 153 }
 154
 155 static int pps_gpio_probe(struct platform_device *pdev)
 156 {
 157         struct pps_gpio_device_data *data;
 158         struct device *dev = &pdev->dev;
 159         int ret;
 160         int pps_default_params;
 161
 162         /* allocate space for device info */
 163         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 164         if (!data)
 165                 return -ENOMEM;
 166
 167         dev_set_drvdata(dev, data);
 168
 169         /* GPIO setup */
 170         ret = pps_gpio_setup(dev);
 171         if (ret)
 172                 return ret;
 173
 174         /* IRQ setup */
 175         ret = gpiod_to_irq(data->gpio_pin);
 176         if (ret < 0) {
 177                 dev_err(dev, "failed to map GPIO to IRQ: %d\n", ret);
 178                 return -EINVAL;
 179         }
 180         data->irq = ret;
 181
 182         /* initialize PPS specific parts of the bookkeeping data structure. */
 183         data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
 184                 PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
 185         if (data->capture_clear)
 186                 data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
 187                         PPS_ECHOCLEAR;
 188         data->info.owner = THIS_MODULE;
 189         snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
 190                  pdev->name, pdev->id);
 191         if (data->echo_pin) {
 192                 data->info.echo = pps_gpio_echo;
 193                 data->echo_timeout = msecs_to_jiffies(data->echo_active_ms);
 194                 timer_setup(&data->echo_timer, pps_gpio_echo_timer_callback, 0);
 195         }
 196
 197         /* register PPS source */
 198         pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
 199         if (data->capture_clear)
 200                 pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
 201         data->pps = pps_register_source(&data->info, pps_default_params);
 202         if (IS_ERR(data->pps)) {
 203                 dev_err(dev, "failed to register IRQ %d as PPS source\n",
 204                         data->irq);
 205                 return PTR_ERR(data->pps);
 206         }
 207
 208         /* register IRQ interrupt handler */
 209         ret = devm_request_irq(dev, data->irq, pps_gpio_irq_handler,
 210                         get_irqf_trigger_flags(data), data->info.name, data);
 211         if (ret) {
 212                 pps_unregister_source(data->pps);
 213                 dev_err(dev, "failed to acquire IRQ %d\n", data->irq);
 214                 return -EINVAL;
 215         }
 216
 217         dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n",
 218                  data->irq);
 219
 220         return 0;
 221 }
 222
 223 static void pps_gpio_remove(struct platform_device *pdev)
 224 {
 225         struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
 226
 227         pps_unregister_source(data->pps);
 228         del_timer_sync(&data->echo_timer);
 229         /* reset echo pin in any case */
 230         gpiod_set_value(data->echo_pin, 0);
 231         dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq);
 232 }
 233
 234 static const struct of_device_id pps_gpio_dt_ids[] = {
 235         { .compatible = "pps-gpio", },
 236         { /* sentinel */ }
 237 };
 238 MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
 239
 240 static struct platform_driver pps_gpio_driver = {
 241         .probe          = pps_gpio_probe,
 242         .remove_new     = pps_gpio_remove,
 243         .driver         = {
 244                 .name   = PPS_GPIO_NAME,
 245                 .of_match_table = pps_gpio_dt_ids,
 246         },
 247 };
 248
 249 module_platform_driver(pps_gpio_driver);
 250 MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
 251 MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
 252 MODULE_DESCRIPTION("Use GPIO pin as PPS source");
 253 MODULE_LICENSE("GPL");
 254 MODULE_VERSION("1.2.0");