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
13 struct clocksource_mmio {
14 void __iomem *reg;
15 struct clocksource clksrc;
16 };
17
to_mmio_clksrc(struct clocksource * c)18 static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
19 {
20 return container_of(c, struct clocksource_mmio, clksrc);
21 }
22
clocksource_mmio_readl_up(struct clocksource * c)23 cycle_t clocksource_mmio_readl_up(struct clocksource *c)
24 {
25 return (cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg);
26 }
27
clocksource_mmio_readl_down(struct clocksource * c)28 cycle_t clocksource_mmio_readl_down(struct clocksource *c)
29 {
30 return ~(cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
31 }
32
clocksource_mmio_readw_up(struct clocksource * c)33 cycle_t clocksource_mmio_readw_up(struct clocksource *c)
34 {
35 return (cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg);
36 }
37
clocksource_mmio_readw_down(struct clocksource * c)38 cycle_t clocksource_mmio_readw_down(struct clocksource *c)
39 {
40 return ~(cycle_t)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 */
clocksource_mmio_init(void __iomem * base,const char * name,unsigned long hz,int rating,unsigned bits,cycle_t (* read)(struct clocksource *))52 int __init clocksource_mmio_init(void __iomem *base, const char *name,
53 unsigned long hz, int rating, unsigned bits,
54 cycle_t (*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