LXR linux/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 */
  27struct 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
  44static 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 */
  68static 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 */
  93static 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
 102static 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
 141static unsigned long
 142get_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
 155static 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 -EINVAL;
 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
 223static int 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        return 0;
 233}
 234
 235static const struct of_device_id pps_gpio_dt_ids[] = {
 236        { .compatible = "pps-gpio", },
 237        { /* sentinel */ }
 238};
 239MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
 240
 241static struct platform_driver pps_gpio_driver = {
 242        .probe          = pps_gpio_probe,
 243        .remove         = pps_gpio_remove,
 244        .driver         = {
 245                .name   = PPS_GPIO_NAME,
 246                .of_match_table = pps_gpio_dt_ids,
 247        },
 248};
 249
 250module_platform_driver(pps_gpio_driver);
 251MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
 252MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
 253MODULE_DESCRIPTION("Use GPIO pin as PPS source");
 254MODULE_LICENSE("GPL");
 255MODULE_VERSION("1.2.0");
 256