LXR linux/drivers/clocksource/mmio.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Generic MMIO clocksource support
   4 */
   5#include <linux/clocksource.h>
   6#include <linux/errno.h>
   7#include <linux/init.h>
   8#include <linux/slab.h>
   9
  10struct clocksource_mmio {
  11        void __iomem *reg;
  12        struct clocksource clksrc;
  13};
  14
  15static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
  16{
  17        return container_of(c, struct clocksource_mmio, clksrc);
  18}
  19
  20u64 clocksource_mmio_readl_up(struct clocksource *c)
  21{
  22        return (u64)readl_relaxed(to_mmio_clksrc(c)->reg);
  23}
  24
  25u64 clocksource_mmio_readl_down(struct clocksource *c)
  26{
  27        return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
  28}
  29
  30u64 clocksource_mmio_readw_up(struct clocksource *c)
  31{
  32        return (u64)readw_relaxed(to_mmio_clksrc(c)->reg);
  33}
  34
  35u64 clocksource_mmio_readw_down(struct clocksource *c)
  36{
  37        return ~(u64)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
  38}
  39
  40/**
  41 * clocksource_mmio_init - Initialize a simple mmio based clocksource
  42 * @base:       Virtual address of the clock readout register
  43 * @name:       Name of the clocksource
  44 * @hz:         Frequency of the clocksource in Hz
  45 * @rating:     Rating of the clocksource
  46 * @bits:       Number of valid bits
  47 * @read:       One of clocksource_mmio_read*() above
  48 */
  49int __init clocksource_mmio_init(void __iomem *base, const char *name,
  50        unsigned long hz, int rating, unsigned bits,
  51        u64 (*read)(struct clocksource *))
  52{
  53        struct clocksource_mmio *cs;
  54
  55        if (bits > 64 || bits < 16)
  56                return -EINVAL;
  57
  58        cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
  59        if (!cs)
  60                return -ENOMEM;
  61
  62        cs->reg = base;
  63        cs->clksrc.name = name;
  64        cs->clksrc.rating = rating;
  65        cs->clksrc.read = read;
  66        cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
  67        cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
  68
  69        return clocksource_register_hz(&cs->clksrc, hz);
  70}
  71