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Diffstat (limited to 'arch/arm/plat-mxc/time.c')
| -rw-r--r-- | arch/arm/plat-mxc/time.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/arch/arm/plat-mxc/time.c b/arch/arm/plat-mxc/time.c new file mode 100644 index 0000000..3bf8634 --- /dev/null +++ b/arch/arm/plat-mxc/time.c @@ -0,0 +1,228 @@ +/* + * linux/arch/arm/plat-mxc/time.c + * + * Copyright (C) 2000-2001 Deep Blue Solutions + * Copyright (C) 2002 Shane Nay (shane@minirl.com) + * Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com) + * Copyright (C) 2008 Juergen Beisert (kernel@pengutronix.de) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, + * MA 02110-1301, USA. + */ + +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/clockchips.h> +#include <linux/clk.h> + +#include <asm/hardware.h> +#include <asm/mach/time.h> +#include <asm/arch/common.h> +#include <asm/arch/mxc_timer.h> + +static struct clock_event_device clockevent_mxc; +static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED; + +/* clock source for the timer */ +static struct clk *timer_clk; + +/* clock source */ + +static cycle_t mxc_get_cycles(void) +{ + return __raw_readl(TIMER_BASE + MXC_TCN); +} + +static struct clocksource clocksource_mxc = { + .name = "mxc_timer1", + .rating = 200, + .read = mxc_get_cycles, + .mask = CLOCKSOURCE_MASK(32), + .shift = 20, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static int __init mxc_clocksource_init(void) +{ + unsigned int clock; + + clock = clk_get_rate(timer_clk); + + clocksource_mxc.mult = clocksource_hz2mult(clock, + clocksource_mxc.shift); + clocksource_register(&clocksource_mxc); + + return 0; +} + +/* clock event */ + +static int mxc_set_next_event(unsigned long evt, + struct clock_event_device *unused) +{ + unsigned long tcmp; + + tcmp = __raw_readl(TIMER_BASE + MXC_TCN) + evt; + __raw_writel(tcmp, TIMER_BASE + MXC_TCMP); + + return (int)(tcmp - __raw_readl(TIMER_BASE + MXC_TCN)) < 0 ? + -ETIME : 0; +} + +#ifdef DEBUG +static const char *clock_event_mode_label[] = { + [CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC", + [CLOCK_EVT_MODE_ONESHOT] = "CLOCK_EVT_MODE_ONESHOT", + [CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN", + [CLOCK_EVT_MODE_UNUSED] = "CLOCK_EVT_MODE_UNUSED" +}; +#endif /* DEBUG */ + +static void mxc_set_mode(enum clock_event_mode mode, + struct clock_event_device *evt) +{ + unsigned long flags; + + /* + * The timer interrupt generation is disabled at least + * for enough time to call mxc_set_next_event() + */ + local_irq_save(flags); + + /* Disable interrupt in GPT module */ + gpt_irq_disable(); + + if (mode != clockevent_mode) { + /* Set event time into far-far future */ + __raw_writel(__raw_readl(TIMER_BASE + MXC_TCN) - 3, + TIMER_BASE + MXC_TCMP); + /* Clear pending interrupt */ + gpt_irq_acknowledge(); + } + +#ifdef DEBUG + printk(KERN_INFO "mxc_set_mode: changing mode from %s to %s\n", + clock_event_mode_label[clockevent_mode], + clock_event_mode_label[mode]); +#endif /* DEBUG */ + + /* Remember timer mode */ + clockevent_mode = mode; + local_irq_restore(flags); + + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + printk(KERN_ERR"mxc_set_mode: Periodic mode is not " + "supported for i.MX\n"); + break; + case CLOCK_EVT_MODE_ONESHOT: + /* + * Do not put overhead of interrupt enable/disable into + * mxc_set_next_event(), the core has about 4 minutes + * to call mxc_set_next_event() or shutdown clock after + * mode switching + */ + local_irq_save(flags); + gpt_irq_enable(); + local_irq_restore(flags); + break; + case CLOCK_EVT_MODE_SHUTDOWN: + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_RESUME: + /* Left event sources disabled, no more interrupts appear */ + break; + } +} + +/* + * IRQ handler for the timer + */ +static irqreturn_t mxc_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = &clockevent_mxc; + uint32_t tstat; + + tstat = __raw_readl(TIMER_BASE + MXC_TSTAT); + + gpt_irq_acknowledge(); + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static struct irqaction mxc_timer_irq = { + .name = "i.MX Timer Tick", + .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, + .handler = mxc_timer_interrupt, +}; + +static struct clock_event_device clockevent_mxc = { + .name = "mxc_timer1", + .features = CLOCK_EVT_FEAT_ONESHOT, + .shift = 32, + .set_mode = mxc_set_mode, + .set_next_event = mxc_set_next_event, + .rating = 200, +}; + +static int __init mxc_clockevent_init(void) +{ + unsigned int clock; + + clock = clk_get_rate(timer_clk); + + clockevent_mxc.mult = div_sc(clock, NSEC_PER_SEC, + clockevent_mxc.shift); + clockevent_mxc.max_delta_ns = + clockevent_delta2ns(0xfffffffe, &clockevent_mxc); + clockevent_mxc.min_delta_ns = + clockevent_delta2ns(0xff, &clockevent_mxc); + + clockevent_mxc.cpumask = cpumask_of_cpu(0); + + clockevents_register_device(&clockevent_mxc); + + return 0; +} + +void __init mxc_timer_init(const char *clk_timer) +{ + timer_clk = clk_get(NULL, clk_timer); + if (!timer_clk) { + printk(KERN_ERR"Cannot determine timer clock. Giving up.\n"); + return; + } + + clk_enable(timer_clk); + + /* + * Initialise to a known state (all timers off, and timing reset) + */ + __raw_writel(0, TIMER_BASE + MXC_TCTL); + __raw_writel(0, TIMER_BASE + MXC_TPRER); /* see datasheet note */ + + __raw_writel(TCTL_FRR | /* free running */ + TCTL_VAL | /* set clocksource and arch specific bits */ + TCTL_TEN, /* start the timer */ + TIMER_BASE + MXC_TCTL); + + /* init and register the timer to the framework */ + mxc_clocksource_init(); + mxc_clockevent_init(); + + /* Make irqs happen */ + setup_irq(TIMER_INTERRUPT, &mxc_timer_irq); +} + |
