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author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2009-09-12 12:02:26 +0100 |
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committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-09-12 12:02:26 +0100 |
commit | ddd559b13f6d2fe3ad68c4b3f5235fd3c2eae4e3 (patch) | |
tree | d827bca3fc825a0ac33efbcd493713be40fcc812 /arch/arm/mach-nomadik/timer.c | |
parent | cf7a2b4fb6a9b86779930a0a123b0df41aa9208f (diff) | |
parent | f17a1f06d2fa93f4825be572622eb02c4894db4e (diff) |
Merge branch 'devel-stable' into devel
Conflicts:
MAINTAINERS
arch/arm/mm/fault.c
Diffstat (limited to 'arch/arm/mach-nomadik/timer.c')
-rw-r--r-- | arch/arm/mach-nomadik/timer.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/arch/arm/mach-nomadik/timer.c b/arch/arm/mach-nomadik/timer.c new file mode 100644 index 00000000000..d1738e7061d --- /dev/null +++ b/arch/arm/mach-nomadik/timer.c @@ -0,0 +1,164 @@ +/* + * linux/arch/arm/mach-nomadik/timer.c + * + * Copyright (C) 2008 STMicroelectronics + * Copyright (C) 2009 Alessandro Rubini, somewhat based on at91sam926x + * + * 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/init.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/io.h> +#include <linux/clockchips.h> +#include <linux/jiffies.h> +#include <asm/mach/time.h> +#include <mach/mtu.h> + +#define TIMER_CTRL 0x80 /* No divisor */ +#define TIMER_PERIODIC 0x40 +#define TIMER_SZ32BIT 0x02 + +/* Initial value for SRC control register: all timers use MXTAL/8 source */ +#define SRC_CR_INIT_MASK 0x00007fff +#define SRC_CR_INIT_VAL 0x2aaa8000 + +static u32 nmdk_count; /* accumulated count */ +static u32 nmdk_cycle; /* write-once */ +static __iomem void *mtu_base; + +/* + * clocksource: the MTU device is a decrementing counters, so we negate + * the value being read. + */ +static cycle_t nmdk_read_timer(struct clocksource *cs) +{ + u32 count = readl(mtu_base + MTU_VAL(0)); + return nmdk_count + nmdk_cycle - count; + +} + +static struct clocksource nmdk_clksrc = { + .name = "mtu_0", + .rating = 120, + .read = nmdk_read_timer, + .shift = 20, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +/* + * Clockevent device: currently only periodic mode is supported + */ +static void nmdk_clkevt_mode(enum clock_event_mode mode, + struct clock_event_device *dev) +{ + unsigned long flags; + + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + /* enable interrupts -- and count current value? */ + raw_local_irq_save(flags); + writel(readl(mtu_base + MTU_IMSC) | 1, mtu_base + MTU_IMSC); + raw_local_irq_restore(flags); + break; + case CLOCK_EVT_MODE_ONESHOT: + BUG(); /* Not supported, yet */ + /* FALLTHROUGH */ + case CLOCK_EVT_MODE_SHUTDOWN: + case CLOCK_EVT_MODE_UNUSED: + /* disable irq */ + raw_local_irq_save(flags); + writel(readl(mtu_base + MTU_IMSC) & ~1, mtu_base + MTU_IMSC); + raw_local_irq_restore(flags); + break; + case CLOCK_EVT_MODE_RESUME: + break; + } +} + +static struct clock_event_device nmdk_clkevt = { + .name = "mtu_0", + .features = CLOCK_EVT_FEAT_PERIODIC, + .shift = 32, + .rating = 100, + .set_mode = nmdk_clkevt_mode, +}; + +/* + * IRQ Handler for the timer 0 of the MTU block. The irq is not shared + * as we are the only users of mtu0 by now. + */ +static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id) +{ + /* ack: "interrupt clear register" */ + writel( 1 << 0, mtu_base + MTU_ICR); + + /* we can't count lost ticks, unfortunately */ + nmdk_count += nmdk_cycle; + nmdk_clkevt.event_handler(&nmdk_clkevt); + + return IRQ_HANDLED; +} + +/* + * Set up timer interrupt, and return the current time in seconds. + */ +static struct irqaction nmdk_timer_irq = { + .name = "Nomadik Timer Tick", + .flags = IRQF_DISABLED | IRQF_TIMER, + .handler = nmdk_timer_interrupt, +}; + +static void nmdk_timer_reset(void) +{ + u32 cr; + + writel(0, mtu_base + MTU_CR(0)); /* off */ + + /* configure load and background-load, and fire it up */ + writel(nmdk_cycle, mtu_base + MTU_LR(0)); + writel(nmdk_cycle, mtu_base + MTU_BGLR(0)); + cr = MTU_CRn_PERIODIC | MTU_CRn_PRESCALE_1 | MTU_CRn_32BITS; + writel(cr, mtu_base + MTU_CR(0)); + writel(cr | MTU_CRn_ENA, mtu_base + MTU_CR(0)); +} + +static void __init nmdk_timer_init(void) +{ + u32 src_cr; + unsigned long rate; + int bits; + + rate = CLOCK_TICK_RATE; /* 2.4MHz */ + nmdk_cycle = (rate + HZ/2) / HZ; + + /* Configure timer sources in "system reset controller" ctrl reg */ + src_cr = readl(io_p2v(NOMADIK_SRC_BASE)); + src_cr &= SRC_CR_INIT_MASK; + src_cr |= SRC_CR_INIT_VAL; + writel(src_cr, io_p2v(NOMADIK_SRC_BASE)); + + /* Save global pointer to mtu, used by functions above */ + mtu_base = io_p2v(NOMADIK_MTU0_BASE); + + /* Init the timer and register clocksource */ + nmdk_timer_reset(); + + nmdk_clksrc.mult = clocksource_hz2mult(rate, nmdk_clksrc.shift); + bits = 8*sizeof(nmdk_count); + nmdk_clksrc.mask = CLOCKSOURCE_MASK(bits); + + clocksource_register(&nmdk_clksrc); + + /* Register irq and clockevents */ + setup_irq(IRQ_MTU0, &nmdk_timer_irq); + nmdk_clkevt.mult = div_sc(rate, NSEC_PER_SEC, nmdk_clkevt.shift); + nmdk_clkevt.cpumask = cpumask_of(0); + clockevents_register_device(&nmdk_clkevt); +} + +struct sys_timer nomadik_timer = { + .init = nmdk_timer_init, +}; |