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
/*
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* Generic MMIO clocksource support
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/clocksource.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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struct clocksource_mmio {
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void __iomem *reg;
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struct clocksource clksrc;
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};
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static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
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{
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return container_of(c, struct clocksource_mmio, clksrc);
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}
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cycle_t clocksource_mmio_readl_up(struct clocksource *c)
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{
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return (cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg);
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}
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cycle_t clocksource_mmio_readl_down(struct clocksource *c)
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{
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return ~(cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
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}
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cycle_t clocksource_mmio_readw_up(struct clocksource *c)
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{
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return (cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg);
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}
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cycle_t clocksource_mmio_readw_down(struct clocksource *c)
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{
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return ~(cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
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}
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/**
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* clocksource_mmio_init - Initialize a simple mmio based clocksource
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* @base: Virtual address of the clock readout register
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* @name: Name of the clocksource
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* @hz: Frequency of the clocksource in Hz
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* @rating: Rating of the clocksource
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* @bits: Number of valid bits
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* @read: One of clocksource_mmio_read*() above
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*/
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int __init clocksource_mmio_init(void __iomem *base, const char *name,
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unsigned long hz, int rating, unsigned bits,
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cycle_t (*read)(struct clocksource *))
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{
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struct clocksource_mmio *cs;
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if (bits > 32 || bits < 16)
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return -EINVAL;
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cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
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if (!cs)
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return -ENOMEM;
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cs->reg = base;
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cs->clksrc.name = name;
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cs->clksrc.rating = rating;
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cs->clksrc.read = read;
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cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
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cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
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return clocksource_register_hz(&cs->clksrc, hz);
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}
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