drivers/clocksource/mmio.c

Source file repositories/reference/linux-study-clean/drivers/clocksource/mmio.c

File Facts

System
Linux kernel
Corpus path
drivers/clocksource/mmio.c
Extension
.c
Size
1980 bytes
Lines
76
Domain
Driver Families
Bucket
drivers/clocksource
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

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);
}

u64 clocksource_mmio_readl_up(struct clocksource *c)
{
	return (u64)readl_relaxed(to_mmio_clksrc(c)->reg);
}
EXPORT_SYMBOL_GPL(clocksource_mmio_readl_up);

u64 clocksource_mmio_readl_down(struct clocksource *c)
{
	return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
}
EXPORT_SYMBOL_GPL(clocksource_mmio_readl_down);

u64 clocksource_mmio_readw_up(struct clocksource *c)
{
	return (u64)readw_relaxed(to_mmio_clksrc(c)->reg);
}
EXPORT_SYMBOL_GPL(clocksource_mmio_readw_up);

u64 clocksource_mmio_readw_down(struct clocksource *c)
{
	return ~(u64)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
}
EXPORT_SYMBOL_GPL(clocksource_mmio_readw_down);

/**
 * 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 clocksource_mmio_init(void __iomem *base, const char *name,
			  unsigned long hz, int rating, unsigned bits,
			  u64 (*read)(struct clocksource *))
{
	struct clocksource_mmio *cs;

	if (bits > 64 || bits < 16)
		return -EINVAL;

	cs = kzalloc_obj(struct clocksource_mmio);
	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);
}
EXPORT_SYMBOL_GPL(clocksource_mmio_init);

Annotation

Implementation Notes