2 * Generic MMIO clocksource support
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.
8 #include <linux/clocksource.h>
9 #include <linux/errno.h>
10 #include <linux/init.h>
11 #include <linux/slab.h>
13 struct clocksource_mmio {
15 struct clocksource clksrc;
18 static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
20 return container_of(c, struct clocksource_mmio, clksrc);
23 cycle_t clocksource_mmio_readl_up(struct clocksource *c)
25 return readl_relaxed(to_mmio_clksrc(c)->reg);
28 cycle_t clocksource_mmio_readl_down(struct clocksource *c)
30 return ~readl_relaxed(to_mmio_clksrc(c)->reg);
33 cycle_t clocksource_mmio_readw_up(struct clocksource *c)
35 return readw_relaxed(to_mmio_clksrc(c)->reg);
38 cycle_t clocksource_mmio_readw_down(struct clocksource *c)
40 return ~(unsigned)readw_relaxed(to_mmio_clksrc(c)->reg);
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
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 *))
56 struct clocksource_mmio *cs;
58 if (bits > 32 || bits < 16)
61 cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
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;
72 return clocksource_register_hz(&cs->clksrc, hz);