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1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* | |
3 | * Copyright 2023 NXP | |
4 | * | |
5 | * Mock-up PTP Hardware Clock driver for virtual network devices | |
6 | * | |
7 | * Create a PTP clock which offers PTP time manipulation operations | |
8 | * using a timecounter/cyclecounter on top of CLOCK_MONOTONIC_RAW. | |
9 | */ | |
10 | ||
11 | #include <linux/ptp_clock_kernel.h> | |
12 | #include <linux/ptp_mock.h> | |
13 | #include <linux/timecounter.h> | |
14 | ||
15 | /* Clamp scaled_ppm between -2,097,152,000 and 2,097,152,000, | |
16 | * and thus "adj" between -68,719,476 and 68,719,476 | |
17 | */ | |
18 | #define MOCK_PHC_MAX_ADJ_PPB 32000000 | |
19 | /* Timestamps from ktime_get_raw() have 1 ns resolution, so the scale factor | |
20 | * (MULT >> SHIFT) needs to be 1. Pick SHIFT as 31 bits, which translates | |
21 | * MULT(freq 0) into 0x80000000. | |
22 | */ | |
23 | #define MOCK_PHC_CC_SHIFT 31 | |
24 | #define MOCK_PHC_CC_MULT (1 << MOCK_PHC_CC_SHIFT) | |
25 | #define MOCK_PHC_FADJ_SHIFT 9 | |
26 | #define MOCK_PHC_FADJ_DENOMINATOR 15625ULL | |
27 | ||
28 | /* The largest cycle_delta that timecounter_read_delta() can handle without a | |
29 | * 64-bit overflow during the multiplication with cc->mult, given the max "adj" | |
30 | * we permit, is ~8.3 seconds. Make sure readouts are more frequent than that. | |
31 | */ | |
32 | #define MOCK_PHC_REFRESH_INTERVAL (HZ * 5) | |
33 | ||
34 | #define info_to_phc(d) container_of((d), struct mock_phc, info) | |
35 | ||
36 | struct mock_phc { | |
37 | struct ptp_clock_info info; | |
38 | struct ptp_clock *clock; | |
39 | struct timecounter tc; | |
40 | struct cyclecounter cc; | |
41 | spinlock_t lock; | |
42 | }; | |
43 | ||
44 | static u64 mock_phc_cc_read(const struct cyclecounter *cc) | |
45 | { | |
46 | return ktime_get_raw_ns(); | |
47 | } | |
48 | ||
49 | static int mock_phc_adjfine(struct ptp_clock_info *info, long scaled_ppm) | |
50 | { | |
51 | struct mock_phc *phc = info_to_phc(info); | |
52 | s64 adj; | |
53 | ||
54 | adj = (s64)scaled_ppm << MOCK_PHC_FADJ_SHIFT; | |
55 | adj = div_s64(adj, MOCK_PHC_FADJ_DENOMINATOR); | |
56 | ||
57 | spin_lock(&phc->lock); | |
58 | timecounter_read(&phc->tc); | |
59 | phc->cc.mult = MOCK_PHC_CC_MULT + adj; | |
60 | spin_unlock(&phc->lock); | |
61 | ||
62 | return 0; | |
63 | } | |
64 | ||
65 | static int mock_phc_adjtime(struct ptp_clock_info *info, s64 delta) | |
66 | { | |
67 | struct mock_phc *phc = info_to_phc(info); | |
68 | ||
69 | spin_lock(&phc->lock); | |
70 | timecounter_adjtime(&phc->tc, delta); | |
71 | spin_unlock(&phc->lock); | |
72 | ||
73 | return 0; | |
74 | } | |
75 | ||
76 | static int mock_phc_settime64(struct ptp_clock_info *info, | |
77 | const struct timespec64 *ts) | |
78 | { | |
79 | struct mock_phc *phc = info_to_phc(info); | |
80 | u64 ns = timespec64_to_ns(ts); | |
81 | ||
82 | spin_lock(&phc->lock); | |
83 | timecounter_init(&phc->tc, &phc->cc, ns); | |
84 | spin_unlock(&phc->lock); | |
85 | ||
86 | return 0; | |
87 | } | |
88 | ||
89 | static int mock_phc_gettime64(struct ptp_clock_info *info, struct timespec64 *ts) | |
90 | { | |
91 | struct mock_phc *phc = info_to_phc(info); | |
92 | u64 ns; | |
93 | ||
94 | spin_lock(&phc->lock); | |
95 | ns = timecounter_read(&phc->tc); | |
96 | spin_unlock(&phc->lock); | |
97 | ||
98 | *ts = ns_to_timespec64(ns); | |
99 | ||
100 | return 0; | |
101 | } | |
102 | ||
103 | static long mock_phc_refresh(struct ptp_clock_info *info) | |
104 | { | |
105 | struct timespec64 ts; | |
106 | ||
107 | mock_phc_gettime64(info, &ts); | |
108 | ||
109 | return MOCK_PHC_REFRESH_INTERVAL; | |
110 | } | |
111 | ||
112 | int mock_phc_index(struct mock_phc *phc) | |
113 | { | |
114 | return ptp_clock_index(phc->clock); | |
115 | } | |
116 | EXPORT_SYMBOL_GPL(mock_phc_index); | |
117 | ||
118 | struct mock_phc *mock_phc_create(struct device *dev) | |
119 | { | |
120 | struct mock_phc *phc; | |
121 | int err; | |
122 | ||
123 | phc = kzalloc(sizeof(*phc), GFP_KERNEL); | |
124 | if (!phc) { | |
125 | err = -ENOMEM; | |
126 | goto out; | |
127 | } | |
128 | ||
129 | phc->info = (struct ptp_clock_info) { | |
130 | .owner = THIS_MODULE, | |
131 | .name = "Mock-up PTP clock", | |
132 | .max_adj = MOCK_PHC_MAX_ADJ_PPB, | |
133 | .adjfine = mock_phc_adjfine, | |
134 | .adjtime = mock_phc_adjtime, | |
135 | .gettime64 = mock_phc_gettime64, | |
136 | .settime64 = mock_phc_settime64, | |
137 | .do_aux_work = mock_phc_refresh, | |
138 | }; | |
139 | ||
140 | phc->cc = (struct cyclecounter) { | |
141 | .read = mock_phc_cc_read, | |
142 | .mask = CYCLECOUNTER_MASK(64), | |
143 | .mult = MOCK_PHC_CC_MULT, | |
144 | .shift = MOCK_PHC_CC_SHIFT, | |
145 | }; | |
146 | ||
147 | spin_lock_init(&phc->lock); | |
148 | timecounter_init(&phc->tc, &phc->cc, 0); | |
149 | ||
150 | phc->clock = ptp_clock_register(&phc->info, dev); | |
151 | if (IS_ERR(phc->clock)) { | |
152 | err = PTR_ERR(phc->clock); | |
153 | goto out_free_phc; | |
154 | } | |
155 | ||
156 | ptp_schedule_worker(phc->clock, MOCK_PHC_REFRESH_INTERVAL); | |
157 | ||
158 | return phc; | |
159 | ||
160 | out_free_phc: | |
161 | kfree(phc); | |
162 | out: | |
163 | return ERR_PTR(err); | |
164 | } | |
165 | EXPORT_SYMBOL_GPL(mock_phc_create); | |
166 | ||
167 | void mock_phc_destroy(struct mock_phc *phc) | |
168 | { | |
169 | ptp_clock_unregister(phc->clock); | |
170 | kfree(phc); | |
171 | } | |
172 | EXPORT_SYMBOL_GPL(mock_phc_destroy); | |
173 | ||
174 | MODULE_DESCRIPTION("Mock-up PTP Hardware Clock driver"); | |
175 | MODULE_LICENSE("GPL"); |