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 #include <linux/of_device.h> 37 #include <linux/of_gpio.h> 38 39 /* Info for each registered platform device */ 40 struct pps_gpio_device_data { 41 int irq; /* IRQ used as PPS source */ 42 struct pps_device *pps; /* PPS source device */ 43 struct pps_source_info info; /* PPS source information */ 44 bool assert_falling_edge; 45 bool capture_clear; 46 unsigned int gpio_pin; 47 }; 48 49 /* 50 * Report the PPS event 51 */ 52 53 static irqreturn_t pps_gpio_irq_handler(int irq, void *data) 54 { 55 const struct pps_gpio_device_data *info; 56 struct pps_event_time ts; 57 int rising_edge; 58 59 /* Get the time stamp first */ 60 pps_get_ts(&ts); 61 62 info = data; 63 64 rising_edge = gpio_get_value(info->gpio_pin); 65 if ((rising_edge && !info->assert_falling_edge) || 66 (!rising_edge && info->assert_falling_edge)) 67 pps_event(info->pps, &ts, PPS_CAPTUREASSERT, NULL); 68 else if (info->capture_clear && 69 ((rising_edge && info->assert_falling_edge) || 70 (!rising_edge && !info->assert_falling_edge))) 71 pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL); 72 73 return IRQ_HANDLED; 74 } 75 76 static unsigned long 77 get_irqf_trigger_flags(const struct pps_gpio_device_data *data) 78 { 79 unsigned long flags = data->assert_falling_edge ? 80 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING; 81 82 if (data->capture_clear) { 83 flags |= ((flags & IRQF_TRIGGER_RISING) ? 84 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING); 85 } 86 87 return flags; 88 } 89 90 static int pps_gpio_probe(struct platform_device *pdev) 91 { 92 struct pps_gpio_device_data *data; 93 const char *gpio_label; 94 int ret; 95 int pps_default_params; 96 const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data; 97 struct device_node *np = pdev->dev.of_node; 98 99 /* allocate space for device info */ 100 data = devm_kzalloc(&pdev->dev, sizeof(struct pps_gpio_device_data), 101 GFP_KERNEL); 102 if (!data) 103 return -ENOMEM; 104 105 if (pdata) { 106 data->gpio_pin = pdata->gpio_pin; 107 gpio_label = pdata->gpio_label; 108 109 data->assert_falling_edge = pdata->assert_falling_edge; 110 data->capture_clear = pdata->capture_clear; 111 } else { 112 ret = of_get_gpio(np, 0); 113 if (ret < 0) { 114 dev_err(&pdev->dev, "failed to get GPIO from device tree\n"); 115 return ret; 116 } 117 data->gpio_pin = ret; 118 gpio_label = PPS_GPIO_NAME; 119 120 if (of_get_property(np, "assert-falling-edge", NULL)) 121 data->assert_falling_edge = true; 122 } 123 124 /* GPIO setup */ 125 ret = devm_gpio_request(&pdev->dev, data->gpio_pin, gpio_label); 126 if (ret) { 127 dev_err(&pdev->dev, "failed to request GPIO %u\n", 128 data->gpio_pin); 129 return ret; 130 } 131 132 ret = gpio_direction_input(data->gpio_pin); 133 if (ret) { 134 dev_err(&pdev->dev, "failed to set pin direction\n"); 135 return -EINVAL; 136 } 137 138 /* IRQ setup */ 139 ret = gpio_to_irq(data->gpio_pin); 140 if (ret < 0) { 141 dev_err(&pdev->dev, "failed to map GPIO to IRQ: %d\n", ret); 142 return -EINVAL; 143 } 144 data->irq = ret; 145 146 /* initialize PPS specific parts of the bookkeeping data structure. */ 147 data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT | 148 PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC; 149 if (data->capture_clear) 150 data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR | 151 PPS_ECHOCLEAR; 152 data->info.owner = THIS_MODULE; 153 snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d", 154 pdev->name, pdev->id); 155 156 /* register PPS source */ 157 pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT; 158 if (data->capture_clear) 159 pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR; 160 data->pps = pps_register_source(&data->info, pps_default_params); 161 if (data->pps == NULL) { 162 dev_err(&pdev->dev, "failed to register IRQ %d as PPS source\n", 163 data->irq); 164 return -EINVAL; 165 } 166 167 /* register IRQ interrupt handler */ 168 ret = devm_request_irq(&pdev->dev, data->irq, pps_gpio_irq_handler, 169 get_irqf_trigger_flags(data), data->info.name, data); 170 if (ret) { 171 pps_unregister_source(data->pps); 172 dev_err(&pdev->dev, "failed to acquire IRQ %d\n", data->irq); 173 return -EINVAL; 174 } 175 176 platform_set_drvdata(pdev, data); 177 dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n", 178 data->irq); 179 180 return 0; 181 } 182 183 static int pps_gpio_remove(struct platform_device *pdev) 184 { 185 struct pps_gpio_device_data *data = platform_get_drvdata(pdev); 186 187 pps_unregister_source(data->pps); 188 dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq); 189 return 0; 190 } 191 192 static const struct of_device_id pps_gpio_dt_ids[] = { 193 { .compatible = "pps-gpio", }, 194 { /* sentinel */ } 195 }; 196 MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids); 197 198 static struct platform_driver pps_gpio_driver = { 199 .probe = pps_gpio_probe, 200 .remove = pps_gpio_remove, 201 .driver = { 202 .name = PPS_GPIO_NAME, 203 .of_match_table = pps_gpio_dt_ids, 204 }, 205 }; 206 207 module_platform_driver(pps_gpio_driver); 208 MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>"); 209 MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>"); 210 MODULE_DESCRIPTION("Use GPIO pin as PPS source"); 211 MODULE_LICENSE("GPL"); 212 MODULE_VERSION("1.0.0"); 213