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 
to_mmio_clksrc(struct clocksource * c)15 static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
16 {
17 	return container_of(c, struct clocksource_mmio, clksrc);
18 }
19 
clocksource_mmio_readl_up(struct clocksource * c)20 u64 clocksource_mmio_readl_up(struct clocksource *c)
21 {
22 	return (u64)readl_relaxed(to_mmio_clksrc(c)->reg);
23 }
24 
clocksource_mmio_readl_down(struct clocksource * c)25 u64 clocksource_mmio_readl_down(struct clocksource *c)
26 {
27 	return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
28 }
29 
clocksource_mmio_readw_up(struct clocksource * c)30 u64 clocksource_mmio_readw_up(struct clocksource *c)
31 {
32 	return (u64)readw_relaxed(to_mmio_clksrc(c)->reg);
33 }
34 
clocksource_mmio_readw_down(struct clocksource * c)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  */
clocksource_mmio_init(void __iomem * base,const char * name,unsigned long hz,int rating,unsigned bits,u64 (* read)(struct clocksource *))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 }
71