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/*
* Generic MMIO clocksource support
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/clocksource.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
struct clocksource_mmio {
void __iomem *reg;
struct clocksource clksrc;
};
static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
{
return container_of(c, struct clocksource_mmio, clksrc);
}
cycle_t clocksource_mmio_readl_up(struct clocksource *c)
{
return (cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg);
}
cycle_t clocksource_mmio_readl_down(struct clocksource *c)
{
return ~(cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
}
cycle_t clocksource_mmio_readw_up(struct clocksource *c)
{
return (cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg);
}
cycle_t clocksource_mmio_readw_down(struct clocksource *c)
{
return ~(cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
}
/**
* clocksource_mmio_init - Initialize a simple mmio based clocksource
* @base: Virtual address of the clock readout register
* @name: Name of the clocksource
* @hz: Frequency of the clocksource in Hz
* @rating: Rating of the clocksource
* @bits: Number of valid bits
* @read: One of clocksource_mmio_read*() above
*/
int __init clocksource_mmio_init(void __iomem *base, const char *name,
unsigned long hz, int rating, unsigned bits,
cycle_t (*read)(struct clocksource *))
{
struct clocksource_mmio *cs;
if (bits > 64 || bits < 16)
return -EINVAL;
cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
if (!cs)
return -ENOMEM;
cs->reg = base;
cs->clksrc.name = name;
cs->clksrc.rating = rating;
cs->clksrc.read = read;
cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
return clocksource_register_hz(&cs->clksrc, hz);
}
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