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1/*
2 * pps_parport.c -- kernel parallel port PPS client
3 *
4 *
5 * Copyright (C) 2009 Alexander Gordeev <lasaine@lvk.cs.msu.su>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22
23/*
24 * TODO:
25 * implement echo over SEL pin
26 */
27
28#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
29
30#include <linux/kernel.h>
31#include <linux/module.h>
32#include <linux/init.h>
33#include <linux/irqnr.h>
34#include <linux/time.h>
35#include <linux/slab.h>
36#include <linux/parport.h>
37#include <linux/pps_kernel.h>
38
39#define DRVDESC "parallel port PPS client"
40
41/* module parameters */
42
43#define CLEAR_WAIT_MAX 100
44#define CLEAR_WAIT_MAX_ERRORS 5
45
46static unsigned int clear_wait = 100;
47MODULE_PARM_DESC(clear_wait,
48 "Maximum number of port reads when polling for signal clear,"
49 " zero turns clear edge capture off entirely");
50module_param(clear_wait, uint, 0);
51
52
53/* internal per port structure */
54struct pps_client_pp {
55 struct pardevice *pardev; /* parport device */
56 struct pps_device *pps; /* PPS device */
57 unsigned int cw; /* port clear timeout */
58 unsigned int cw_err; /* number of timeouts */
59};
60
61static inline int signal_is_set(struct parport *port)
62{
63 return (port->ops->read_status(port) & PARPORT_STATUS_ACK) != 0;
64}
65
66/* parport interrupt handler */
67static void parport_irq(void *handle)
68{
69 struct pps_event_time ts_assert, ts_clear;
70 struct pps_client_pp *dev = handle;
71 struct parport *port = dev->pardev->port;
72 unsigned int i;
73 unsigned long flags;
74
75 /* first of all we get the time stamp... */
76 pps_get_ts(&ts_assert);
77
78 if (dev->cw == 0)
79 /* clear edge capture disabled */
80 goto out_assert;
81
82 /* try capture the clear edge */
83
84 /* We have to disable interrupts here. The idea is to prevent
85 * other interrupts on the same processor to introduce random
86 * lags while polling the port. Reading from IO port is known
87 * to take approximately 1us while other interrupt handlers can
88 * take much more potentially.
89 *
90 * Interrupts won't be disabled for a long time because the
91 * number of polls is limited by clear_wait parameter which is
92 * kept rather low. So it should never be an issue.
93 */
94 local_irq_save(flags);
95 /* check the signal (no signal means the pulse is lost this time) */
96 if (!signal_is_set(port)) {
97 local_irq_restore(flags);
98 dev_err(dev->pps->dev, "lost the signal\n");
99 goto out_assert;
100 }
101
102 /* poll the port until the signal is unset */
103 for (i = dev->cw; i; i--)
104 if (!signal_is_set(port)) {
105 pps_get_ts(&ts_clear);
106 local_irq_restore(flags);
107 dev->cw_err = 0;
108 goto out_both;
109 }
110 local_irq_restore(flags);
111
112 /* timeout */
113 dev->cw_err++;
114 if (dev->cw_err >= CLEAR_WAIT_MAX_ERRORS) {
115 dev_err(dev->pps->dev, "disabled clear edge capture after %d"
116 " timeouts\n", dev->cw_err);
117 dev->cw = 0;
118 dev->cw_err = 0;
119 }
120
121out_assert:
122 /* fire assert event */
123 pps_event(dev->pps, &ts_assert,
124 PPS_CAPTUREASSERT, NULL);
125 return;
126
127out_both:
128 /* fire assert event */
129 pps_event(dev->pps, &ts_assert,
130 PPS_CAPTUREASSERT, NULL);
131 /* fire clear event */
132 pps_event(dev->pps, &ts_clear,
133 PPS_CAPTURECLEAR, NULL);
134 return;
135}
136
137static void parport_attach(struct parport *port)
138{
139 struct pps_client_pp *device;
140 struct pps_source_info info = {
141 .name = KBUILD_MODNAME,
142 .path = "",
143 .mode = PPS_CAPTUREBOTH | \
144 PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
145 PPS_ECHOASSERT | PPS_ECHOCLEAR | \
146 PPS_CANWAIT | PPS_TSFMT_TSPEC,
147 .owner = THIS_MODULE,
148 .dev = NULL
149 };
150
151 device = kzalloc(sizeof(struct pps_client_pp), GFP_KERNEL);
152 if (!device) {
153 pr_err("memory allocation failed, not attaching\n");
154 return;
155 }
156
157 device->pardev = parport_register_device(port, KBUILD_MODNAME,
158 NULL, NULL, parport_irq, PARPORT_FLAG_EXCL, device);
159 if (!device->pardev) {
160 pr_err("couldn't register with %s\n", port->name);
161 goto err_free;
162 }
163
164 if (parport_claim_or_block(device->pardev) < 0) {
165 pr_err("couldn't claim %s\n", port->name);
166 goto err_unregister_dev;
167 }
168
169 device->pps = pps_register_source(&info,
170 PPS_CAPTUREBOTH | PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
171 if (device->pps == NULL) {
172 pr_err("couldn't register PPS source\n");
173 goto err_release_dev;
174 }
175
176 device->cw = clear_wait;
177
178 port->ops->enable_irq(port);
179
180 pr_info("attached to %s\n", port->name);
181
182 return;
183
184err_release_dev:
185 parport_release(device->pardev);
186err_unregister_dev:
187 parport_unregister_device(device->pardev);
188err_free:
189 kfree(device);
190}
191
192static void parport_detach(struct parport *port)
193{
194 struct pardevice *pardev = port->cad;
195 struct pps_client_pp *device;
196
197 /* FIXME: oooh, this is ugly! */
198 if (strcmp(pardev->name, KBUILD_MODNAME))
199 /* not our port */
200 return;
201
202 device = pardev->private;
203
204 port->ops->disable_irq(port);
205 pps_unregister_source(device->pps);
206 parport_release(pardev);
207 parport_unregister_device(pardev);
208 kfree(device);
209}
210
211static struct parport_driver pps_parport_driver = {
212 .name = KBUILD_MODNAME,
213 .attach = parport_attach,
214 .detach = parport_detach,
215};
216
217/* module staff */
218
219static int __init pps_parport_init(void)
220{
221 int ret;
222
223 pr_info(DRVDESC "\n");
224
225 if (clear_wait > CLEAR_WAIT_MAX) {
226 pr_err("clear_wait value should be not greater"
227 " then %d\n", CLEAR_WAIT_MAX);
228 return -EINVAL;
229 }
230
231 ret = parport_register_driver(&pps_parport_driver);
232 if (ret) {
233 pr_err("unable to register with parport\n");
234 return ret;
235 }
236
237 return 0;
238}
239
240static void __exit pps_parport_exit(void)
241{
242 parport_unregister_driver(&pps_parport_driver);
243}
244
245module_init(pps_parport_init);
246module_exit(pps_parport_exit);
247
248MODULE_AUTHOR("Alexander Gordeev <lasaine@lvk.cs.msu.su>");
249MODULE_DESCRIPTION(DRVDESC);
250MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * pps_parport.c -- kernel parallel port PPS client
4 *
5 * Copyright (C) 2009 Alexander Gordeev <lasaine@lvk.cs.msu.su>
6 */
7
8
9/*
10 * TODO:
11 * implement echo over SEL pin
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/init.h>
19#include <linux/irqnr.h>
20#include <linux/time.h>
21#include <linux/slab.h>
22#include <linux/parport.h>
23#include <linux/pps_kernel.h>
24
25#define DRVDESC "parallel port PPS client"
26
27/* module parameters */
28
29#define CLEAR_WAIT_MAX 100
30#define CLEAR_WAIT_MAX_ERRORS 5
31
32static unsigned int clear_wait = 100;
33MODULE_PARM_DESC(clear_wait,
34 "Maximum number of port reads when polling for signal clear,"
35 " zero turns clear edge capture off entirely");
36module_param(clear_wait, uint, 0);
37
38static DEFINE_IDA(pps_client_index);
39
40/* internal per port structure */
41struct pps_client_pp {
42 struct pardevice *pardev; /* parport device */
43 struct pps_device *pps; /* PPS device */
44 unsigned int cw; /* port clear timeout */
45 unsigned int cw_err; /* number of timeouts */
46 int index; /* device number */
47};
48
49static inline int signal_is_set(struct parport *port)
50{
51 return (port->ops->read_status(port) & PARPORT_STATUS_ACK) != 0;
52}
53
54/* parport interrupt handler */
55static void parport_irq(void *handle)
56{
57 struct pps_event_time ts_assert, ts_clear;
58 struct pps_client_pp *dev = handle;
59 struct parport *port = dev->pardev->port;
60 unsigned int i;
61 unsigned long flags;
62
63 /* first of all we get the time stamp... */
64 pps_get_ts(&ts_assert);
65
66 if (dev->cw == 0)
67 /* clear edge capture disabled */
68 goto out_assert;
69
70 /* try capture the clear edge */
71
72 /* We have to disable interrupts here. The idea is to prevent
73 * other interrupts on the same processor to introduce random
74 * lags while polling the port. Reading from IO port is known
75 * to take approximately 1us while other interrupt handlers can
76 * take much more potentially.
77 *
78 * Interrupts won't be disabled for a long time because the
79 * number of polls is limited by clear_wait parameter which is
80 * kept rather low. So it should never be an issue.
81 */
82 local_irq_save(flags);
83 /* check the signal (no signal means the pulse is lost this time) */
84 if (!signal_is_set(port)) {
85 local_irq_restore(flags);
86 dev_err(dev->pps->dev, "lost the signal\n");
87 goto out_assert;
88 }
89
90 /* poll the port until the signal is unset */
91 for (i = dev->cw; i; i--)
92 if (!signal_is_set(port)) {
93 pps_get_ts(&ts_clear);
94 local_irq_restore(flags);
95 dev->cw_err = 0;
96 goto out_both;
97 }
98 local_irq_restore(flags);
99
100 /* timeout */
101 dev->cw_err++;
102 if (dev->cw_err >= CLEAR_WAIT_MAX_ERRORS) {
103 dev_err(dev->pps->dev, "disabled clear edge capture after %d"
104 " timeouts\n", dev->cw_err);
105 dev->cw = 0;
106 dev->cw_err = 0;
107 }
108
109out_assert:
110 /* fire assert event */
111 pps_event(dev->pps, &ts_assert,
112 PPS_CAPTUREASSERT, NULL);
113 return;
114
115out_both:
116 /* fire assert event */
117 pps_event(dev->pps, &ts_assert,
118 PPS_CAPTUREASSERT, NULL);
119 /* fire clear event */
120 pps_event(dev->pps, &ts_clear,
121 PPS_CAPTURECLEAR, NULL);
122 return;
123}
124
125static void parport_attach(struct parport *port)
126{
127 struct pardev_cb pps_client_cb;
128 int index;
129 struct pps_client_pp *device;
130 struct pps_source_info info = {
131 .name = KBUILD_MODNAME,
132 .path = "",
133 .mode = PPS_CAPTUREBOTH | \
134 PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
135 PPS_ECHOASSERT | PPS_ECHOCLEAR | \
136 PPS_CANWAIT | PPS_TSFMT_TSPEC,
137 .owner = THIS_MODULE,
138 .dev = NULL
139 };
140
141 device = kzalloc(sizeof(struct pps_client_pp), GFP_KERNEL);
142 if (!device) {
143 pr_err("memory allocation failed, not attaching\n");
144 return;
145 }
146
147 index = ida_simple_get(&pps_client_index, 0, 0, GFP_KERNEL);
148 memset(&pps_client_cb, 0, sizeof(pps_client_cb));
149 pps_client_cb.private = device;
150 pps_client_cb.irq_func = parport_irq;
151 pps_client_cb.flags = PARPORT_FLAG_EXCL;
152 device->pardev = parport_register_dev_model(port,
153 KBUILD_MODNAME,
154 &pps_client_cb,
155 index);
156 if (!device->pardev) {
157 pr_err("couldn't register with %s\n", port->name);
158 goto err_free;
159 }
160
161 if (parport_claim_or_block(device->pardev) < 0) {
162 pr_err("couldn't claim %s\n", port->name);
163 goto err_unregister_dev;
164 }
165
166 device->pps = pps_register_source(&info,
167 PPS_CAPTUREBOTH | PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
168 if (IS_ERR(device->pps)) {
169 pr_err("couldn't register PPS source\n");
170 goto err_release_dev;
171 }
172
173 device->cw = clear_wait;
174
175 port->ops->enable_irq(port);
176 device->index = index;
177
178 pr_info("attached to %s\n", port->name);
179
180 return;
181
182err_release_dev:
183 parport_release(device->pardev);
184err_unregister_dev:
185 parport_unregister_device(device->pardev);
186err_free:
187 ida_simple_remove(&pps_client_index, index);
188 kfree(device);
189}
190
191static void parport_detach(struct parport *port)
192{
193 struct pardevice *pardev = port->cad;
194 struct pps_client_pp *device;
195
196 /* FIXME: oooh, this is ugly! */
197 if (!pardev || strcmp(pardev->name, KBUILD_MODNAME))
198 /* not our port */
199 return;
200
201 device = pardev->private;
202
203 port->ops->disable_irq(port);
204 pps_unregister_source(device->pps);
205 parport_release(pardev);
206 parport_unregister_device(pardev);
207 ida_simple_remove(&pps_client_index, device->index);
208 kfree(device);
209}
210
211static struct parport_driver pps_parport_driver = {
212 .name = KBUILD_MODNAME,
213 .match_port = parport_attach,
214 .detach = parport_detach,
215 .devmodel = true,
216};
217
218/* module staff */
219
220static int __init pps_parport_init(void)
221{
222 int ret;
223
224 pr_info(DRVDESC "\n");
225
226 if (clear_wait > CLEAR_WAIT_MAX) {
227 pr_err("clear_wait value should be not greater"
228 " then %d\n", CLEAR_WAIT_MAX);
229 return -EINVAL;
230 }
231
232 ret = parport_register_driver(&pps_parport_driver);
233 if (ret) {
234 pr_err("unable to register with parport\n");
235 return ret;
236 }
237
238 return 0;
239}
240
241static void __exit pps_parport_exit(void)
242{
243 parport_unregister_driver(&pps_parport_driver);
244}
245
246module_init(pps_parport_init);
247module_exit(pps_parport_exit);
248
249MODULE_AUTHOR("Alexander Gordeev <lasaine@lvk.cs.msu.su>");
250MODULE_DESCRIPTION(DRVDESC);
251MODULE_LICENSE("GPL");