mirror of
https://github.com/torvalds/linux
synced 2024-11-05 18:23:50 +00:00
95c19a06ec
For some clocksource devices, for example, the registers are 32-bit, while the lower 16-bit is used for timer counting(And reading the upper 16-bit will return 0). For example, when the counter value is 0x00001111, and then the ~readl_relaxed(to_mmio_clksrc(c)->reg) will return the value of 0xFFFFEEEE, but it should be 0x0000EEEE. So just using the c->mask to mask the unused bits. Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
73 lines
1.9 KiB
C
73 lines
1.9 KiB
C
/*
|
|
* 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 > 32 || 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);
|
|
}
|