/* * linux/arch/arm/mach-at91/at91sam926x_time.c * * Copyright (C) 2005-2006 M. Amine SAYA, ATMEL Rousset, France * Revision 2005 M. Nicolas Diremdjian, ATMEL Rousset, France * * 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/kernel.h> #include <linux/sched.h> #include <linux/time.h> #include <asm/hardware.h> #include <asm/io.h> #include <asm/mach/time.h> #include <asm/arch/at91_pit.h> #define PIT_CPIV(x) ((x) & AT91_PIT_CPIV) #define PIT_PICNT(x) (((x) & AT91_PIT_PICNT) >> 20) /* * Returns number of microseconds since last timer interrupt. Note that interrupts * will have been disabled by do_gettimeofday() * 'LATCH' is hwclock ticks (see CLOCK_TICK_RATE in timex.h) per jiffy. */ static unsigned long at91sam926x_gettimeoffset(void) { unsigned long elapsed; unsigned long t = at91_sys_read(AT91_PIT_PIIR); elapsed = (PIT_PICNT(t) * LATCH) + PIT_CPIV(t); /* hardware clock cycles */ return (unsigned long)(elapsed * jiffies_to_usecs(1)) / LATCH; } /* * IRQ handler for the timer. */ static irqreturn_t at91sam926x_timer_interrupt(int irq, void *dev_id) { volatile long nr_ticks; if (at91_sys_read(AT91_PIT_SR) & AT91_PIT_PITS) { /* This is a shared interrupt */ write_seqlock(&xtime_lock); /* Get number to ticks performed before interrupt and clear PIT interrupt */ nr_ticks = PIT_PICNT(at91_sys_read(AT91_PIT_PIVR)); do { timer_tick(); nr_ticks--; } while (nr_ticks); write_sequnlock(&xtime_lock); return IRQ_HANDLED; } else return IRQ_NONE; /* not handled */ } static struct irqaction at91sam926x_timer_irq = { .name = "at91_tick", .flags = IRQF_SHARED | IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, .handler = at91sam926x_timer_interrupt }; void at91sam926x_timer_reset(void) { /* Disable timer */ at91_sys_write(AT91_PIT_MR, 0); /* Clear any pending interrupts */ (void) at91_sys_read(AT91_PIT_PIVR); /* Set Period Interval timer and enable its interrupt */ at91_sys_write(AT91_PIT_MR, (LATCH & AT91_PIT_PIV) | AT91_PIT_PITIEN | AT91_PIT_PITEN); } /* * Set up timer interrupt. */ void __init at91sam926x_timer_init(void) { /* Initialize and enable the timer */ at91sam926x_timer_reset(); /* Make IRQs happen for the system timer. */ setup_irq(AT91_ID_SYS, &at91sam926x_timer_irq); } #ifdef CONFIG_PM static void at91sam926x_timer_suspend(void) { /* Disable timer */ at91_sys_write(AT91_PIT_MR, 0); } #else #define at91sam926x_timer_suspend NULL #endif struct sys_timer at91sam926x_timer = { .init = at91sam926x_timer_init, .offset = at91sam926x_gettimeoffset, .suspend = at91sam926x_timer_suspend, .resume = at91sam926x_timer_reset, };