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
10struct clocksource_mmio {
11	void __iomem *reg;
12	struct clocksource clksrc;
13};
14
15static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
16{
17	return container_of(c, struct clocksource_mmio, clksrc);
18}
19
20u64 clocksource_mmio_readl_up(struct clocksource *c)
21{
22	return (u64)readl_relaxed(to_mmio_clksrc(c)->reg);
23}
24
25u64 clocksource_mmio_readl_down(struct clocksource *c)
26{
27	return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
28}
29
30u64 clocksource_mmio_readw_up(struct clocksource *c)
31{
32	return (u64)readw_relaxed(to_mmio_clksrc(c)->reg);
33}
34
35u64 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 */
49int __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}
71