1/*
2 * Generic MMIO clocksource support
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8#include <linux/clocksource.h>
9#include <linux/errno.h>
10#include <linux/init.h>
11#include <linux/slab.h>
12
13struct clocksource_mmio {
14 void __iomem *reg;
15 struct clocksource clksrc;
16};
17
18static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
19{
20 return container_of(c, struct clocksource_mmio, clksrc);
21}
22
23u64 clocksource_mmio_readl_up(struct clocksource *c)
24{
25 return (u64)readl_relaxed(to_mmio_clksrc(c)->reg);
26}
27
28u64 clocksource_mmio_readl_down(struct clocksource *c)
29{
30 return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
31}
32
33u64 clocksource_mmio_readw_up(struct clocksource *c)
34{
35 return (u64)readw_relaxed(to_mmio_clksrc(c)->reg);
36}
37
38u64 clocksource_mmio_readw_down(struct clocksource *c)
39{
40 return ~(u64)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
41}
42
43/**
44 * clocksource_mmio_init - Initialize a simple mmio based clocksource
45 * @base: Virtual address of the clock readout register
46 * @name: Name of the clocksource
47 * @hz: Frequency of the clocksource in Hz
48 * @rating: Rating of the clocksource
49 * @bits: Number of valid bits
50 * @read: One of clocksource_mmio_read*() above
51 */
52int __init clocksource_mmio_init(void __iomem *base, const char *name,
53 unsigned long hz, int rating, unsigned bits,
54 u64 (*read)(struct clocksource *))
55{
56 struct clocksource_mmio *cs;
57
58 if (bits > 64 || bits < 16)
59 return -EINVAL;
60
61 cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
62 if (!cs)
63 return -ENOMEM;
64
65 cs->reg = base;
66 cs->clksrc.name = name;
67 cs->clksrc.rating = rating;
68 cs->clksrc.read = read;
69 cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
70 cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
71
72 return clocksource_register_hz(&cs->clksrc, hz);
73}
74