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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/*
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/parport.h>
36#include <linux/pps_kernel.h>
37
38#define DRVDESC "parallel port PPS client"
39
40/* module parameters */
41
42#define CLEAR_WAIT_MAX 100
43#define CLEAR_WAIT_MAX_ERRORS 5
44
45static unsigned int clear_wait = 100;
46MODULE_PARM_DESC(clear_wait,
47 "Maximum number of port reads when polling for signal clear,"
48 " zero turns clear edge capture off entirely");
49module_param(clear_wait, uint, 0);
50
51
52/* internal per port structure */
53struct pps_client_pp {
54 struct pardevice *pardev; /* parport device */
55 struct pps_device *pps; /* PPS device */
56 unsigned int cw; /* port clear timeout */
57 unsigned int cw_err; /* number of timeouts */
58};
59
60static inline int signal_is_set(struct parport *port)
61{
62 return (port->ops->read_status(port) & PARPORT_STATUS_ACK) != 0;
63}
64
65/* parport interrupt handler */
66static void parport_irq(void *handle)
67{
68 struct pps_event_time ts_assert, ts_clear;
69 struct pps_client_pp *dev = handle;
70 struct parport *port = dev->pardev->port;
71 unsigned int i;
72 unsigned long flags;
73
74 /* first of all we get the time stamp... */
75 pps_get_ts(&ts_assert);
76
77 if (dev->cw == 0)
78 /* clear edge capture disabled */
79 goto out_assert;
80
81 /* try capture the clear edge */
82
83 /* We have to disable interrupts here. The idea is to prevent
84 * other interrupts on the same processor to introduce random
85 * lags while polling the port. Reading from IO port is known
86 * to take approximately 1us while other interrupt handlers can
87 * take much more potentially.
88 *
89 * Interrupts won't be disabled for a long time because the
90 * number of polls is limited by clear_wait parameter which is
91 * kept rather low. So it should never be an issue.
92 */
93 local_irq_save(flags);
94 /* check the signal (no signal means the pulse is lost this time) */
95 if (!signal_is_set(port)) {
96 local_irq_restore(flags);
97 dev_err(dev->pps->dev, "lost the signal\n");
98 goto out_assert;
99 }
100
101 /* poll the port until the signal is unset */
102 for (i = dev->cw; i; i--)
103 if (!signal_is_set(port)) {
104 pps_get_ts(&ts_clear);
105 local_irq_restore(flags);
106 dev->cw_err = 0;
107 goto out_both;
108 }
109 local_irq_restore(flags);
110
111 /* timeout */
112 dev->cw_err++;
113 if (dev->cw_err >= CLEAR_WAIT_MAX_ERRORS) {
114 dev_err(dev->pps->dev, "disabled clear edge capture after %d"
115 " timeouts\n", dev->cw_err);
116 dev->cw = 0;
117 dev->cw_err = 0;
118 }
119
120out_assert:
121 /* fire assert event */
122 pps_event(dev->pps, &ts_assert,
123 PPS_CAPTUREASSERT, NULL);
124 return;
125
126out_both:
127 /* fire assert event */
128 pps_event(dev->pps, &ts_assert,
129 PPS_CAPTUREASSERT, NULL);
130 /* fire clear event */
131 pps_event(dev->pps, &ts_clear,
132 PPS_CAPTURECLEAR, NULL);
133 return;
134}
135
136/* the PPS echo function */
137static void pps_echo(struct pps_device *pps, int event, void *data)
138{
139 dev_info(pps->dev, "echo %s %s\n",
140 event & PPS_CAPTUREASSERT ? "assert" : "",
141 event & PPS_CAPTURECLEAR ? "clear" : "");
142}
143
144static void parport_attach(struct parport *port)
145{
146 struct pps_client_pp *device;
147 struct pps_source_info info = {
148 .name = KBUILD_MODNAME,
149 .path = "",
150 .mode = PPS_CAPTUREBOTH | \
151 PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
152 PPS_ECHOASSERT | PPS_ECHOCLEAR | \
153 PPS_CANWAIT | PPS_TSFMT_TSPEC,
154 .echo = pps_echo,
155 .owner = THIS_MODULE,
156 .dev = NULL
157 };
158
159 device = kzalloc(sizeof(struct pps_client_pp), GFP_KERNEL);
160 if (!device) {
161 pr_err("memory allocation failed, not attaching\n");
162 return;
163 }
164
165 device->pardev = parport_register_device(port, KBUILD_MODNAME,
166 NULL, NULL, parport_irq, PARPORT_FLAG_EXCL, device);
167 if (!device->pardev) {
168 pr_err("couldn't register with %s\n", port->name);
169 goto err_free;
170 }
171
172 if (parport_claim_or_block(device->pardev) < 0) {
173 pr_err("couldn't claim %s\n", port->name);
174 goto err_unregister_dev;
175 }
176
177 device->pps = pps_register_source(&info,
178 PPS_CAPTUREBOTH | PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
179 if (device->pps == NULL) {
180 pr_err("couldn't register PPS source\n");
181 goto err_release_dev;
182 }
183
184 device->cw = clear_wait;
185
186 port->ops->enable_irq(port);
187
188 pr_info("attached to %s\n", port->name);
189
190 return;
191
192err_release_dev:
193 parport_release(device->pardev);
194err_unregister_dev:
195 parport_unregister_device(device->pardev);
196err_free:
197 kfree(device);
198}
199
200static void parport_detach(struct parport *port)
201{
202 struct pardevice *pardev = port->cad;
203 struct pps_client_pp *device;
204
205 /* FIXME: oooh, this is ugly! */
206 if (strcmp(pardev->name, KBUILD_MODNAME))
207 /* not our port */
208 return;
209
210 device = pardev->private;
211
212 port->ops->disable_irq(port);
213 pps_unregister_source(device->pps);
214 parport_release(pardev);
215 parport_unregister_device(pardev);
216 kfree(device);
217}
218
219static struct parport_driver pps_parport_driver = {
220 .name = KBUILD_MODNAME,
221 .attach = parport_attach,
222 .detach = parport_detach,
223};
224
225/* module staff */
226
227static int __init pps_parport_init(void)
228{
229 int ret;
230
231 pr_info(DRVDESC "\n");
232
233 if (clear_wait > CLEAR_WAIT_MAX) {
234 pr_err("clear_wait value should be not greater"
235 " then %d\n", CLEAR_WAIT_MAX);
236 return -EINVAL;
237 }
238
239 ret = parport_register_driver(&pps_parport_driver);
240 if (ret) {
241 pr_err("unable to register with parport\n");
242 return ret;
243 }
244
245 return 0;
246}
247
248static void __exit pps_parport_exit(void)
249{
250 parport_unregister_driver(&pps_parport_driver);
251}
252
253module_init(pps_parport_init);
254module_exit(pps_parport_exit);
255
256MODULE_AUTHOR("Alexander Gordeev <lasaine@lvk.cs.msu.su>");
257MODULE_DESCRIPTION(DRVDESC);
258MODULE_LICENSE("GPL");