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 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 } 234 235 static const struct of_device_id pps_gpio_dt_ids[] = { 236 { .compatible = "pps-gpio", }, 237 { /* sentinel */ } 238 }; 239 MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids); 240 241 static 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 }; 249 250 module_platform_driver(pps_gpio_driver); 251 MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>"); 252 MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>"); 253 MODULE_DESCRIPTION("Use GPIO pin as PPS source"); 254 MODULE_LICENSE("GPL"); 255 MODULE_VERSION("1.2.0"); 256