From 1a0ed732afdbd4b960a4b93f78fddc71b8076e61 Mon Sep 17 00:00:00 2001 From: Andrew Victor Date: Fri, 1 Dec 2006 09:04:47 +0100 Subject: [ARM] 3949/2: AT91: SAM9 timer driver Add support for the timer on the Atmel AT91SAM9261 and AT91SAM9260 processors. Signed-off-by: Andrew Victor Signed-off-by: Russell King --- arch/arm/mach-at91rm9200/at91sam926x_time.c | 114 ++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+) create mode 100644 arch/arm/mach-at91rm9200/at91sam926x_time.c (limited to 'arch/arm/mach-at91rm9200/at91sam926x_time.c') diff --git a/arch/arm/mach-at91rm9200/at91sam926x_time.c b/arch/arm/mach-at91rm9200/at91sam926x_time.c new file mode 100644 index 00000000000..99df5f6ee42 --- /dev/null +++ b/arch/arm/mach-at91rm9200/at91sam926x_time.c @@ -0,0 +1,114 @@ +/* + * linux/arch/arm/mach-at91rm9200/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 +#include +#include +#include +#include +#include + +#include +#include +#include + +#include + + +#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. + * 'tick' is usecs per jiffy (linux/timex.h). + */ +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 * 1000000) / 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, + .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, +}; + -- cgit v1.2.3