diff options
Diffstat (limited to 'drivers/clocksource')
| -rw-r--r-- | drivers/clocksource/Kconfig | 5 | ||||
| -rw-r--r-- | drivers/clocksource/Makefile | 2 | ||||
| -rw-r--r-- | drivers/clocksource/cyclone.c | 10 | ||||
| -rw-r--r-- | drivers/clocksource/i8253.c | 88 | ||||
| -rw-r--r-- | drivers/clocksource/mmio.c | 73 |
5 files changed, 170 insertions, 8 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig new file mode 100644 index 00000000000..96c92191046 --- /dev/null +++ b/drivers/clocksource/Kconfig @@ -0,0 +1,5 @@ +config CLKSRC_I8253 + bool + +config CLKSRC_MMIO + bool diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile index be61ece6330..b995942a506 100644 --- a/drivers/clocksource/Makefile +++ b/drivers/clocksource/Makefile @@ -6,3 +6,5 @@ obj-$(CONFIG_CS5535_CLOCK_EVENT_SRC) += cs5535-clockevt.o obj-$(CONFIG_SH_TIMER_CMT) += sh_cmt.o obj-$(CONFIG_SH_TIMER_MTU2) += sh_mtu2.o obj-$(CONFIG_SH_TIMER_TMU) += sh_tmu.o +obj-$(CONFIG_CLKSRC_I8253) += i8253.o +obj-$(CONFIG_CLKSRC_MMIO) += mmio.o diff --git a/drivers/clocksource/cyclone.c b/drivers/clocksource/cyclone.c index 64e528e8bfa..72f811f73e9 100644 --- a/drivers/clocksource/cyclone.c +++ b/drivers/clocksource/cyclone.c @@ -29,8 +29,6 @@ static struct clocksource clocksource_cyclone = { .rating = 250, .read = read_cyclone, .mask = CYCLONE_TIMER_MASK, - .mult = 10, - .shift = 0, .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; @@ -108,12 +106,8 @@ static int __init init_cyclone_clocksource(void) } cyclone_ptr = cyclone_timer; - /* sort out mult/shift values: */ - clocksource_cyclone.shift = 22; - clocksource_cyclone.mult = clocksource_hz2mult(CYCLONE_TIMER_FREQ, - clocksource_cyclone.shift); - - return clocksource_register(&clocksource_cyclone); + return clocksource_register_hz(&clocksource_cyclone, + CYCLONE_TIMER_FREQ); } arch_initcall(init_cyclone_clocksource); diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c new file mode 100644 index 00000000000..225c1761b37 --- /dev/null +++ b/drivers/clocksource/i8253.c @@ -0,0 +1,88 @@ +/* + * i8253 PIT clocksource + */ +#include <linux/clocksource.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/spinlock.h> +#include <linux/timex.h> + +#include <asm/i8253.h> + +/* + * Since the PIT overflows every tick, its not very useful + * to just read by itself. So use jiffies to emulate a free + * running counter: + */ +static cycle_t i8253_read(struct clocksource *cs) +{ + static int old_count; + static u32 old_jifs; + unsigned long flags; + int count; + u32 jifs; + + raw_spin_lock_irqsave(&i8253_lock, flags); + /* + * Although our caller may have the read side of xtime_lock, + * this is now a seqlock, and we are cheating in this routine + * by having side effects on state that we cannot undo if + * there is a collision on the seqlock and our caller has to + * retry. (Namely, old_jifs and old_count.) So we must treat + * jiffies as volatile despite the lock. We read jiffies + * before latching the timer count to guarantee that although + * the jiffies value might be older than the count (that is, + * the counter may underflow between the last point where + * jiffies was incremented and the point where we latch the + * count), it cannot be newer. + */ + jifs = jiffies; + outb_pit(0x00, PIT_MODE); /* latch the count ASAP */ + count = inb_pit(PIT_CH0); /* read the latched count */ + count |= inb_pit(PIT_CH0) << 8; + + /* VIA686a test code... reset the latch if count > max + 1 */ + if (count > LATCH) { + outb_pit(0x34, PIT_MODE); + outb_pit(PIT_LATCH & 0xff, PIT_CH0); + outb_pit(PIT_LATCH >> 8, PIT_CH0); + count = PIT_LATCH - 1; + } + + /* + * It's possible for count to appear to go the wrong way for a + * couple of reasons: + * + * 1. The timer counter underflows, but we haven't handled the + * resulting interrupt and incremented jiffies yet. + * 2. Hardware problem with the timer, not giving us continuous time, + * the counter does small "jumps" upwards on some Pentium systems, + * (see c't 95/10 page 335 for Neptun bug.) + * + * Previous attempts to handle these cases intelligently were + * buggy, so we just do the simple thing now. + */ + if (count > old_count && jifs == old_jifs) + count = old_count; + + old_count = count; + old_jifs = jifs; + + raw_spin_unlock_irqrestore(&i8253_lock, flags); + + count = (PIT_LATCH - 1) - count; + + return (cycle_t)(jifs * PIT_LATCH) + count; +} + +static struct clocksource i8253_cs = { + .name = "pit", + .rating = 110, + .read = i8253_read, + .mask = CLOCKSOURCE_MASK(32), +}; + +int __init clocksource_i8253_init(void) +{ + return clocksource_register_hz(&i8253_cs, PIT_TICK_RATE); +} diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c new file mode 100644 index 00000000000..c0e25125a55 --- /dev/null +++ b/drivers/clocksource/mmio.c @@ -0,0 +1,73 @@ +/* + * 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 readl_relaxed(to_mmio_clksrc(c)->reg); +} + +cycle_t clocksource_mmio_readl_down(struct clocksource *c) +{ + return ~readl_relaxed(to_mmio_clksrc(c)->reg); +} + +cycle_t clocksource_mmio_readw_up(struct clocksource *c) +{ + return readw_relaxed(to_mmio_clksrc(c)->reg); +} + +cycle_t clocksource_mmio_readw_down(struct clocksource *c) +{ + return ~(unsigned)readw_relaxed(to_mmio_clksrc(c)->reg); +} + +/** + * 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); +} |