tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
37/* Info for each registered platform device */
38struct pps_gpio_device_data {
39 int irq; /* IRQ used as PPS source */
40 struct pps_device *pps; /* PPS source device */
41 struct pps_source_info info; /* PPS source information */
42 const struct pps_gpio_platform_data *pdata;
43};
44
45/*
46 * Report the PPS event
47 */
48
49static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
50{
51 const struct pps_gpio_device_data *info;
52 struct pps_event_time ts;
53 int rising_edge;
54
55 /* Get the time stamp first */
56 pps_get_ts(&ts);
57
58 info = data;
59
60 rising_edge = gpio_get_value(info->pdata->gpio_pin);
61 if ((rising_edge && !info->pdata->assert_falling_edge) ||
62 (!rising_edge && info->pdata->assert_falling_edge))
63 pps_event(info->pps, &ts, PPS_CAPTUREASSERT, NULL);
64 else if (info->pdata->capture_clear &&
65 ((rising_edge && info->pdata->assert_falling_edge) ||
66 (!rising_edge && !info->pdata->assert_falling_edge)))
67 pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL);
68
69 return IRQ_HANDLED;
70}
71
72static int pps_gpio_setup(struct platform_device *pdev)
73{
74 int ret;
75 const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
76
77 ret = gpio_request(pdata->gpio_pin, pdata->gpio_label);
78 if (ret) {
79 pr_warning("failed to request GPIO %u\n", pdata->gpio_pin);
80 return -EINVAL;
81 }
82
83 ret = gpio_direction_input(pdata->gpio_pin);
84 if (ret) {
85 pr_warning("failed to set pin direction\n");
86 gpio_free(pdata->gpio_pin);
87 return -EINVAL;
88 }
89
90 return 0;
91}
92
93static unsigned long
94get_irqf_trigger_flags(const struct pps_gpio_platform_data *pdata)
95{
96 unsigned long flags = pdata->assert_falling_edge ?
97 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
98
99 if (pdata->capture_clear) {
100 flags |= ((flags & IRQF_TRIGGER_RISING) ?
101 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
102 }
103
104 return flags;
105}
106
107static int pps_gpio_probe(struct platform_device *pdev)
108{
109 struct pps_gpio_device_data *data;
110 int irq;
111 int ret;
112 int err;
113 int pps_default_params;
114 const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
115
116
117 /* GPIO setup */
118 ret = pps_gpio_setup(pdev);
119 if (ret)
120 return -EINVAL;
121
122 /* IRQ setup */
123 irq = gpio_to_irq(pdata->gpio_pin);
124 if (irq < 0) {
125 pr_err("failed to map GPIO to IRQ: %d\n", irq);
126 err = -EINVAL;
127 goto return_error;
128 }
129
130 /* allocate space for device info */
131 data = kzalloc(sizeof(struct pps_gpio_device_data), GFP_KERNEL);
132 if (data == NULL) {
133 err = -ENOMEM;
134 goto return_error;
135 }
136
137 /* initialize PPS specific parts of the bookkeeping data structure. */
138 data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
139 PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
140 if (pdata->capture_clear)
141 data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
142 PPS_ECHOCLEAR;
143 data->info.owner = THIS_MODULE;
144 snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
145 pdev->name, pdev->id);
146
147 /* register PPS source */
148 pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
149 if (pdata->capture_clear)
150 pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
151 data->pps = pps_register_source(&data->info, pps_default_params);
152 if (data->pps == NULL) {
153 kfree(data);
154 pr_err("failed to register IRQ %d as PPS source\n", irq);
155 err = -EINVAL;
156 goto return_error;
157 }
158
159 data->irq = irq;
160 data->pdata = pdata;
161
162 /* register IRQ interrupt handler */
163 ret = request_irq(irq, pps_gpio_irq_handler,
164 get_irqf_trigger_flags(pdata), data->info.name, data);
165 if (ret) {
166 pps_unregister_source(data->pps);
167 kfree(data);
168 pr_err("failed to acquire IRQ %d\n", irq);
169 err = -EINVAL;
170 goto return_error;
171 }
172
173 platform_set_drvdata(pdev, data);
174 dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n", irq);
175
176 return 0;
177
178return_error:
179 gpio_free(pdata->gpio_pin);
180 return err;
181}
182
183static int pps_gpio_remove(struct platform_device *pdev)
184{
185 struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
186 const struct pps_gpio_platform_data *pdata = data->pdata;
187
188 platform_set_drvdata(pdev, NULL);
189 free_irq(data->irq, data);
190 gpio_free(pdata->gpio_pin);
191 pps_unregister_source(data->pps);
192 pr_info("removed IRQ %d as PPS source\n", data->irq);
193 kfree(data);
194 return 0;
195}
196
197static struct platform_driver pps_gpio_driver = {
198 .probe = pps_gpio_probe,
199 .remove = pps_gpio_remove,
200 .driver = {
201 .name = PPS_GPIO_NAME,
202 .owner = THIS_MODULE
203 },
204};
205
206static int __init pps_gpio_init(void)
207{
208 int ret = platform_driver_register(&pps_gpio_driver);
209 if (ret < 0)
210 pr_err("failed to register platform driver\n");
211 return ret;
212}
213
214static void __exit pps_gpio_exit(void)
215{
216 platform_driver_unregister(&pps_gpio_driver);
217 pr_debug("unregistered platform driver\n");
218}
219
220module_init(pps_gpio_init);
221module_exit(pps_gpio_exit);
222
223MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
224MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
225MODULE_DESCRIPTION("Use GPIO pin as PPS source");
226MODULE_LICENSE("GPL");
227MODULE_VERSION("1.0.0");