// SPDX-License-Identifier: GPL-2.0-only
/*
 * Generic MMIO clocksource support
 */
#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);
}

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

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

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

u64 clocksource_mmio_readw_down(struct clocksource *c)
{
        return ~(u64)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,
        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);
}