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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/* module parameters */
26
27#define CLEAR_WAIT_MAX 100
28#define CLEAR_WAIT_MAX_ERRORS 5
29
30static unsigned int clear_wait = 100;
31MODULE_PARM_DESC(clear_wait,
32 "Maximum number of port reads when polling for signal clear,"
33 " zero turns clear edge capture off entirely");
34module_param(clear_wait, uint, 0);
35
36static DEFINE_IDA(pps_client_index);
37
38/* internal per port structure */
39struct pps_client_pp {
40 struct pardevice *pardev; /* parport device */
41 struct pps_device *pps; /* PPS device */
42 unsigned int cw; /* port clear timeout */
43 unsigned int cw_err; /* number of timeouts */
44 int index; /* device number */
45};
46
47static inline int signal_is_set(struct parport *port)
48{
49 return (port->ops->read_status(port) & PARPORT_STATUS_ACK) != 0;
50}
51
52/* parport interrupt handler */
53static void parport_irq(void *handle)
54{
55 struct pps_event_time ts_assert, ts_clear;
56 struct pps_client_pp *dev = handle;
57 struct parport *port = dev->pardev->port;
58 unsigned int i;
59 unsigned long flags;
60
61 /* first of all we get the time stamp... */
62 pps_get_ts(&ts_assert);
63
64 if (dev->cw == 0)
65 /* clear edge capture disabled */
66 goto out_assert;
67
68 /* try capture the clear edge */
69
70 /* We have to disable interrupts here. The idea is to prevent
71 * other interrupts on the same processor to introduce random
72 * lags while polling the port. Reading from IO port is known
73 * to take approximately 1us while other interrupt handlers can
74 * take much more potentially.
75 *
76 * Interrupts won't be disabled for a long time because the
77 * number of polls is limited by clear_wait parameter which is
78 * kept rather low. So it should never be an issue.
79 */
80 local_irq_save(flags);
81 /* check the signal (no signal means the pulse is lost this time) */
82 if (!signal_is_set(port)) {
83 local_irq_restore(flags);
84 dev_err(dev->pps->dev, "lost the signal\n");
85 goto out_assert;
86 }
87
88 /* poll the port until the signal is unset */
89 for (i = dev->cw; i; i--)
90 if (!signal_is_set(port)) {
91 pps_get_ts(&ts_clear);
92 local_irq_restore(flags);
93 dev->cw_err = 0;
94 goto out_both;
95 }
96 local_irq_restore(flags);
97
98 /* timeout */
99 dev->cw_err++;
100 if (dev->cw_err >= CLEAR_WAIT_MAX_ERRORS) {
101 dev_err(dev->pps->dev, "disabled clear edge capture after %d"
102 " timeouts\n", dev->cw_err);
103 dev->cw = 0;
104 dev->cw_err = 0;
105 }
106
107out_assert:
108 /* fire assert event */
109 pps_event(dev->pps, &ts_assert,
110 PPS_CAPTUREASSERT, NULL);
111 return;
112
113out_both:
114 /* fire assert event */
115 pps_event(dev->pps, &ts_assert,
116 PPS_CAPTUREASSERT, NULL);
117 /* fire clear event */
118 pps_event(dev->pps, &ts_clear,
119 PPS_CAPTURECLEAR, NULL);
120 return;
121}
122
123static void parport_attach(struct parport *port)
124{
125 struct pardev_cb pps_client_cb;
126 int index;
127 struct pps_client_pp *device;
128 struct pps_source_info info = {
129 .name = KBUILD_MODNAME,
130 .path = "",
131 .mode = PPS_CAPTUREBOTH | \
132 PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
133 PPS_ECHOASSERT | PPS_ECHOCLEAR | \
134 PPS_CANWAIT | PPS_TSFMT_TSPEC,
135 .owner = THIS_MODULE,
136 .dev = NULL
137 };
138
139 if (clear_wait > CLEAR_WAIT_MAX) {
140 pr_err("clear_wait value should be not greater then %d\n",
141 CLEAR_WAIT_MAX);
142 return;
143 }
144
145 device = kzalloc(sizeof(struct pps_client_pp), GFP_KERNEL);
146 if (!device) {
147 pr_err("memory allocation failed, not attaching\n");
148 return;
149 }
150
151 index = ida_simple_get(&pps_client_index, 0, 0, GFP_KERNEL);
152 memset(&pps_client_cb, 0, sizeof(pps_client_cb));
153 pps_client_cb.private = device;
154 pps_client_cb.irq_func = parport_irq;
155 pps_client_cb.flags = PARPORT_FLAG_EXCL;
156 device->pardev = parport_register_dev_model(port,
157 KBUILD_MODNAME,
158 &pps_client_cb,
159 index);
160 if (!device->pardev) {
161 pr_err("couldn't register with %s\n", port->name);
162 goto err_free;
163 }
164
165 if (parport_claim_or_block(device->pardev) < 0) {
166 pr_err("couldn't claim %s\n", port->name);
167 goto err_unregister_dev;
168 }
169
170 device->pps = pps_register_source(&info,
171 PPS_CAPTUREBOTH | PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
172 if (IS_ERR(device->pps)) {
173 pr_err("couldn't register PPS source\n");
174 goto err_release_dev;
175 }
176
177 device->cw = clear_wait;
178
179 port->ops->enable_irq(port);
180 device->index = index;
181
182 pr_info("attached to %s\n", port->name);
183
184 return;
185
186err_release_dev:
187 parport_release(device->pardev);
188err_unregister_dev:
189 parport_unregister_device(device->pardev);
190err_free:
191 ida_simple_remove(&pps_client_index, index);
192 kfree(device);
193}
194
195static void parport_detach(struct parport *port)
196{
197 struct pardevice *pardev = port->cad;
198 struct pps_client_pp *device;
199
200 /* FIXME: oooh, this is ugly! */
201 if (!pardev || strcmp(pardev->name, KBUILD_MODNAME))
202 /* not our port */
203 return;
204
205 device = pardev->private;
206
207 port->ops->disable_irq(port);
208 pps_unregister_source(device->pps);
209 parport_release(pardev);
210 parport_unregister_device(pardev);
211 ida_simple_remove(&pps_client_index, device->index);
212 kfree(device);
213}
214
215static struct parport_driver pps_parport_driver = {
216 .name = KBUILD_MODNAME,
217 .match_port = parport_attach,
218 .detach = parport_detach,
219 .devmodel = true,
220};
221module_parport_driver(pps_parport_driver);
222
223MODULE_AUTHOR("Alexander Gordeev <lasaine@lvk.cs.msu.su>");
224MODULE_DESCRIPTION("parallel port PPS client");
225MODULE_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");