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1 | // SPDX-License-Identifier: GPL-2.0-only | |
2 | /* | |
3 | * Generic MMIO clocksource support | |
4 | */ | |
5 | #include <linux/clocksource.h> | |
6 | #include <linux/errno.h> | |
7 | #include <linux/init.h> | |
8 | #include <linux/slab.h> | |
9 | ||
10 | struct clocksource_mmio { | |
11 | void __iomem *reg; | |
12 | struct clocksource clksrc; | |
13 | }; | |
14 | ||
15 | static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c) | |
16 | { | |
17 | return container_of(c, struct clocksource_mmio, clksrc); | |
18 | } | |
19 | ||
20 | u64 clocksource_mmio_readl_up(struct clocksource *c) | |
21 | { | |
22 | return (u64)readl_relaxed(to_mmio_clksrc(c)->reg); | |
23 | } | |
24 | ||
25 | u64 clocksource_mmio_readl_down(struct clocksource *c) | |
26 | { | |
27 | return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask; | |
28 | } | |
29 | ||
30 | u64 clocksource_mmio_readw_up(struct clocksource *c) | |
31 | { | |
32 | return (u64)readw_relaxed(to_mmio_clksrc(c)->reg); | |
33 | } | |
34 | ||
35 | u64 clocksource_mmio_readw_down(struct clocksource *c) | |
36 | { | |
37 | return ~(u64)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask; | |
38 | } | |
39 | ||
40 | /** | |
41 | * clocksource_mmio_init - Initialize a simple mmio based clocksource | |
42 | * @base: Virtual address of the clock readout register | |
43 | * @name: Name of the clocksource | |
44 | * @hz: Frequency of the clocksource in Hz | |
45 | * @rating: Rating of the clocksource | |
46 | * @bits: Number of valid bits | |
47 | * @read: One of clocksource_mmio_read*() above | |
48 | */ | |
49 | int __init clocksource_mmio_init(void __iomem *base, const char *name, | |
50 | unsigned long hz, int rating, unsigned bits, | |
51 | u64 (*read)(struct clocksource *)) | |
52 | { | |
53 | struct clocksource_mmio *cs; | |
54 | ||
55 | if (bits > 64 || bits < 16) | |
56 | return -EINVAL; | |
57 | ||
58 | cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL); | |
59 | if (!cs) | |
60 | return -ENOMEM; | |
61 | ||
62 | cs->reg = base; | |
63 | cs->clksrc.name = name; | |
64 | cs->clksrc.rating = rating; | |
65 | cs->clksrc.read = read; | |
66 | cs->clksrc.mask = CLOCKSOURCE_MASK(bits); | |
67 | cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS; | |
68 | ||
69 | return clocksource_register_hz(&cs->clksrc, hz); | |
70 | } |