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 /* Small trick to bypass the check on edge's direction when capture_clear is unset */ 56 rising_edge = info->capture_clear ? 57 gpiod_get_value(info->gpio_pin) : !info->assert_falling_edge; 58 if ((rising_edge && !info->assert_falling_edge) || 59 (!rising_edge && info->assert_falling_edge)) 60 pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data); 61 else if (info->capture_clear && 62 ((rising_edge && info->assert_falling_edge) || 63 (!rising_edge && !info->assert_falling_edge))) 64 pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data); 65 else 66 dev_warn_ratelimited(&info->pps->dev, "IRQ did not trigger any PPS event\n"); 67 68 return IRQ_HANDLED; 69 } 70 71 /* This function will only be called when an ECHO GPIO is defined */ 72 static void pps_gpio_echo(struct pps_device *pps, int event, void *data) 73 { 74 /* add_timer() needs to write into info->echo_timer */ 75 struct pps_gpio_device_data *info = data; 76 77 switch (event) { 78 case PPS_CAPTUREASSERT: 79 if (pps->params.mode & PPS_ECHOASSERT) 80 gpiod_set_value(info->echo_pin, 1); 81 break; 82 83 case PPS_CAPTURECLEAR: 84 if (pps->params.mode & PPS_ECHOCLEAR) 85 gpiod_set_value(info->echo_pin, 1); 86 break; 87 } 88 89 /* fire the timer */ 90 if (info->pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) { 91 info->echo_timer.expires = jiffies + info->echo_timeout; 92 add_timer(&info->echo_timer); 93 } 94 } 95 96 /* Timer callback to reset the echo pin to the inactive state */ 97 static void pps_gpio_echo_timer_callback(struct timer_list *t) 98 { 99 const struct pps_gpio_device_data *info; 100 101 info = timer_container_of(info, t, echo_timer); 102 103 gpiod_set_value(info->echo_pin, 0); 104 } 105 106 static int pps_gpio_setup(struct device *dev) 107 { 108 struct pps_gpio_device_data *data = dev_get_drvdata(dev); 109 int ret; 110 u32 value; 111 112 data->gpio_pin = devm_gpiod_get(dev, NULL, GPIOD_IN); 113 if (IS_ERR(data->gpio_pin)) 114 return dev_err_probe(dev, PTR_ERR(data->gpio_pin), 115 "failed to request PPS GPIO\n"); 116 117 data->assert_falling_edge = 118 device_property_read_bool(dev, "assert-falling-edge"); 119 120 data->echo_pin = devm_gpiod_get_optional(dev, "echo", GPIOD_OUT_LOW); 121 if (IS_ERR(data->echo_pin)) 122 return dev_err_probe(dev, PTR_ERR(data->echo_pin), 123 "failed to request ECHO GPIO\n"); 124 125 if (!data->echo_pin) 126 return 0; 127 128 ret = device_property_read_u32(dev, "echo-active-ms", &value); 129 if (ret) { 130 dev_err(dev, "failed to get echo-active-ms from FW\n"); 131 return ret; 132 } 133 134 /* sanity check on echo_active_ms */ 135 if (!value || value > 999) { 136 dev_err(dev, "echo-active-ms: %u - bad value from FW\n", value); 137 return -EINVAL; 138 } 139 140 data->echo_active_ms = value; 141 142 return 0; 143 } 144 145 static unsigned long 146 get_irqf_trigger_flags(const struct pps_gpio_device_data *data) 147 { 148 unsigned long flags = data->assert_falling_edge ? 149 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING; 150 151 if (data->capture_clear) { 152 flags |= ((flags & IRQF_TRIGGER_RISING) ? 153 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING); 154 } 155 156 return flags; 157 } 158 159 static int pps_gpio_probe(struct platform_device *pdev) 160 { 161 struct pps_gpio_device_data *data; 162 struct device *dev = &pdev->dev; 163 int ret; 164 int pps_default_params; 165 166 /* allocate space for device info */ 167 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 168 if (!data) 169 return -ENOMEM; 170 171 dev_set_drvdata(dev, data); 172 173 /* GPIO setup */ 174 ret = pps_gpio_setup(dev); 175 if (ret) 176 return ret; 177 178 /* IRQ setup */ 179 ret = gpiod_to_irq(data->gpio_pin); 180 if (ret < 0) { 181 dev_err(dev, "failed to map GPIO to IRQ: %d\n", ret); 182 return -EINVAL; 183 } 184 data->irq = ret; 185 186 /* initialize PPS specific parts of the bookkeeping data structure. */ 187 data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT | 188 PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC; 189 if (data->capture_clear) 190 data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR | 191 PPS_ECHOCLEAR; 192 data->info.owner = THIS_MODULE; 193 snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d", 194 pdev->name, pdev->id); 195 if (data->echo_pin) { 196 data->info.echo = pps_gpio_echo; 197 data->echo_timeout = msecs_to_jiffies(data->echo_active_ms); 198 timer_setup(&data->echo_timer, pps_gpio_echo_timer_callback, 0); 199 } 200 201 /* register PPS source */ 202 pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT; 203 if (data->capture_clear) 204 pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR; 205 data->pps = pps_register_source(&data->info, pps_default_params); 206 if (IS_ERR(data->pps)) { 207 dev_err(dev, "failed to register IRQ %d as PPS source\n", 208 data->irq); 209 return PTR_ERR(data->pps); 210 } 211 212 /* register IRQ interrupt handler */ 213 ret = devm_request_irq(dev, data->irq, pps_gpio_irq_handler, 214 get_irqf_trigger_flags(data), data->info.name, data); 215 if (ret) { 216 pps_unregister_source(data->pps); 217 dev_err(dev, "failed to acquire IRQ %d\n", data->irq); 218 return -EINVAL; 219 } 220 221 dev_dbg(&data->pps->dev, "Registered IRQ %d as PPS source\n", 222 data->irq); 223 224 return 0; 225 } 226 227 static void pps_gpio_remove(struct platform_device *pdev) 228 { 229 struct pps_gpio_device_data *data = platform_get_drvdata(pdev); 230 231 pps_unregister_source(data->pps); 232 timer_delete_sync(&data->echo_timer); 233 /* reset echo pin in any case */ 234 gpiod_set_value(data->echo_pin, 0); 235 dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq); 236 } 237 238 static const struct of_device_id pps_gpio_dt_ids[] = { 239 { .compatible = "pps-gpio", }, 240 { /* sentinel */ } 241 }; 242 MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids); 243 244 static struct platform_driver pps_gpio_driver = { 245 .probe = pps_gpio_probe, 246 .remove = pps_gpio_remove, 247 .driver = { 248 .name = PPS_GPIO_NAME, 249 .of_match_table = pps_gpio_dt_ids, 250 }, 251 }; 252 253 module_platform_driver(pps_gpio_driver); 254 MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>"); 255 MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>"); 256 MODULE_DESCRIPTION("Use GPIO pin as PPS source"); 257 MODULE_LICENSE("GPL"); 258 MODULE_VERSION("1.2.0"); 259