1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Generic MMIO clocksource support
4*4882a593Smuzhiyun */
5*4882a593Smuzhiyun #include <linux/clocksource.h>
6*4882a593Smuzhiyun #include <linux/errno.h>
7*4882a593Smuzhiyun #include <linux/init.h>
8*4882a593Smuzhiyun #include <linux/slab.h>
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun struct clocksource_mmio {
11*4882a593Smuzhiyun void __iomem *reg;
12*4882a593Smuzhiyun struct clocksource clksrc;
13*4882a593Smuzhiyun };
14*4882a593Smuzhiyun
to_mmio_clksrc(struct clocksource * c)15*4882a593Smuzhiyun static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
16*4882a593Smuzhiyun {
17*4882a593Smuzhiyun return container_of(c, struct clocksource_mmio, clksrc);
18*4882a593Smuzhiyun }
19*4882a593Smuzhiyun
clocksource_mmio_readl_up(struct clocksource * c)20*4882a593Smuzhiyun u64 clocksource_mmio_readl_up(struct clocksource *c)
21*4882a593Smuzhiyun {
22*4882a593Smuzhiyun return (u64)readl_relaxed(to_mmio_clksrc(c)->reg);
23*4882a593Smuzhiyun }
24*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(clocksource_mmio_readl_up);
25*4882a593Smuzhiyun
clocksource_mmio_readl_down(struct clocksource * c)26*4882a593Smuzhiyun u64 clocksource_mmio_readl_down(struct clocksource *c)
27*4882a593Smuzhiyun {
28*4882a593Smuzhiyun return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
29*4882a593Smuzhiyun }
30*4882a593Smuzhiyun
clocksource_mmio_readw_up(struct clocksource * c)31*4882a593Smuzhiyun u64 clocksource_mmio_readw_up(struct clocksource *c)
32*4882a593Smuzhiyun {
33*4882a593Smuzhiyun return (u64)readw_relaxed(to_mmio_clksrc(c)->reg);
34*4882a593Smuzhiyun }
35*4882a593Smuzhiyun
clocksource_mmio_readw_down(struct clocksource * c)36*4882a593Smuzhiyun u64 clocksource_mmio_readw_down(struct clocksource *c)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun return ~(u64)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
39*4882a593Smuzhiyun }
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun /**
42*4882a593Smuzhiyun * clocksource_mmio_init - Initialize a simple mmio based clocksource
43*4882a593Smuzhiyun * @base: Virtual address of the clock readout register
44*4882a593Smuzhiyun * @name: Name of the clocksource
45*4882a593Smuzhiyun * @hz: Frequency of the clocksource in Hz
46*4882a593Smuzhiyun * @rating: Rating of the clocksource
47*4882a593Smuzhiyun * @bits: Number of valid bits
48*4882a593Smuzhiyun * @read: One of clocksource_mmio_read*() above
49*4882a593Smuzhiyun */
clocksource_mmio_init(void __iomem * base,const char * name,unsigned long hz,int rating,unsigned bits,u64 (* read)(struct clocksource *))50*4882a593Smuzhiyun int clocksource_mmio_init(void __iomem *base, const char *name,
51*4882a593Smuzhiyun unsigned long hz, int rating, unsigned bits,
52*4882a593Smuzhiyun u64 (*read)(struct clocksource *))
53*4882a593Smuzhiyun {
54*4882a593Smuzhiyun struct clocksource_mmio *cs;
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun if (bits > 64 || bits < 16)
57*4882a593Smuzhiyun return -EINVAL;
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
60*4882a593Smuzhiyun if (!cs)
61*4882a593Smuzhiyun return -ENOMEM;
62*4882a593Smuzhiyun
63*4882a593Smuzhiyun cs->reg = base;
64*4882a593Smuzhiyun cs->clksrc.name = name;
65*4882a593Smuzhiyun cs->clksrc.rating = rating;
66*4882a593Smuzhiyun cs->clksrc.read = read;
67*4882a593Smuzhiyun cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
68*4882a593Smuzhiyun cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun return clocksource_register_hz(&cs->clksrc, hz);
71*4882a593Smuzhiyun }
72*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(clocksource_mmio_init);
73