1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * PPS kernel consumer API
4 *
5 * Copyright (C) 2009-2010 Alexander Gordeev <lasaine@lvk.cs.msu.su>
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/device.h>
13 #include <linux/init.h>
14 #include <linux/spinlock.h>
15 #include <linux/pps_kernel.h>
16
17 #include "kc.h"
18
19 /*
20 * Global variables
21 */
22
23 /* state variables to bind kernel consumer */
24 static DEFINE_SPINLOCK(pps_kc_hardpps_lock);
25 /* PPS API (RFC 2783): current source and mode for kernel consumer */
26 static struct pps_device *pps_kc_hardpps_dev; /* unique pointer to device */
27 static int pps_kc_hardpps_mode; /* mode bits for kernel consumer */
28
29 /* pps_kc_bind - control PPS kernel consumer binding
30 * @pps: the PPS source
31 * @bind_args: kernel consumer bind parameters
32 *
33 * This function is used to bind or unbind PPS kernel consumer according to
34 * supplied parameters. Should not be called in interrupt context.
35 */
36 int pps_kc_bind(struct pps_device *pps, struct pps_bind_args *bind_args)
37 {
38 /* Check if another consumer is already bound */
39 spin_lock_irq(&pps_kc_hardpps_lock);
40
41 if (bind_args->edge == 0)
42 if (pps_kc_hardpps_dev == pps) {
43 pps_kc_hardpps_mode = 0;
44 pps_kc_hardpps_dev = NULL;
45 spin_unlock_irq(&pps_kc_hardpps_lock);
46 dev_info(pps->dev, "unbound kernel"
47 " consumer\n");
48 } else {
49 spin_unlock_irq(&pps_kc_hardpps_lock);
50 dev_err(pps->dev, "selected kernel consumer"
51 " is not bound\n");
52 return -EINVAL;
53 }
54 else
55 if (pps_kc_hardpps_dev == NULL ||
56 pps_kc_hardpps_dev == pps) {
57 pps_kc_hardpps_mode = bind_args->edge;
58 pps_kc_hardpps_dev = pps;
59 spin_unlock_irq(&pps_kc_hardpps_lock);
60 dev_info(pps->dev, "bound kernel consumer: "
61 "edge=0x%x\n", bind_args->edge);
62 } else {
63 spin_unlock_irq(&pps_kc_hardpps_lock);
64 dev_err(pps->dev, "another kernel consumer"
65 " is already bound\n");
66 return -EINVAL;
67 }
68
69 return 0;
70 }
71
72 /* pps_kc_remove - unbind kernel consumer on PPS source removal
73 * @pps: the PPS source
74 *
75 * This function is used to disable kernel consumer on PPS source removal
76 * if this source was bound to PPS kernel consumer. Can be called on any
77 * source safely. Should not be called in interrupt context.
78 */
79 void pps_kc_remove(struct pps_device *pps)
80 {
81 spin_lock_irq(&pps_kc_hardpps_lock);
82 if (pps == pps_kc_hardpps_dev) {
83 pps_kc_hardpps_mode = 0;
84 pps_kc_hardpps_dev = NULL;
85 spin_unlock_irq(&pps_kc_hardpps_lock);
86 dev_info(pps->dev, "unbound kernel consumer"
87 " on device removal\n");
88 } else
89 spin_unlock_irq(&pps_kc_hardpps_lock);
90 }
91
92 /* pps_kc_event - call hardpps() on PPS event
93 * @pps: the PPS source
94 * @ts: PPS event timestamp
95 * @event: PPS event edge
96 *
97 * This function calls hardpps() when an event from bound PPS source occurs.
98 */
99 void pps_kc_event(struct pps_device *pps, struct pps_event_time *ts,
100 int event)
101 {
102 unsigned long flags;
103
104 /* Pass some events to kernel consumer if activated */
105 spin_lock_irqsave(&pps_kc_hardpps_lock, flags);
106 if (pps == pps_kc_hardpps_dev && event & pps_kc_hardpps_mode)
107 hardpps(&ts->ts_real, &ts->ts_raw);
108 spin_unlock_irqrestore(&pps_kc_hardpps_lock, flags);
109 }