This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / arch / arm / mach-at91rm9200 / at91rm9200_time.c

diff --git a/arch/arm/mach-at91rm9200/at91rm9200_time.c b/arch/arm/mach-at91rm9200/at91rm9200_time.c
new file mode 100644 (file)
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+++ b/arch/arm/mach-at91rm9200/at91rm9200_time.c
@@ -0,0 +1,141 @@
+/*
+ * linux/arch/arm/mach-at91rm9200/at91rm9200_time.c
+ *
+ *  Copyright (C) 2003 SAN People
+ *  Copyright (C) 2003 ATMEL
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#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>
+
+static unsigned long last_crtr;
+
+/*
+ * The ST_CRTR is updated asynchronously to the master clock.  It is therefore
+ *  necessary to read it twice (with the same value) to ensure accuracy.
+ */
+static inline unsigned long read_CRTR(void) {
+       unsigned long x1, x2;
+
+       do {
+               x1 = at91_sys_read(AT91_ST_CRTR);
+               x2 = at91_sys_read(AT91_ST_CRTR);
+       } while (x1 != x2);
+
+       return x1;
+}
+
+/*
+ * 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 at91rm9200_gettimeoffset(void)
+{
+       unsigned long elapsed;
+
+       elapsed = (read_CRTR() - last_crtr) & AT91_ST_ALMV;
+
+       return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
+}
+
+/*
+ * IRQ handler for the timer.
+ */
+static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+       if (at91_sys_read(AT91_ST_SR) & AT91_ST_PITS) { /* This is a shared interrupt */
+               write_seqlock(&xtime_lock);
+
+               while (((read_CRTR() - last_crtr) & AT91_ST_ALMV) >= LATCH) {
+                       timer_tick(regs);
+                       last_crtr = (last_crtr + LATCH) & AT91_ST_ALMV;
+               }
+
+               write_sequnlock(&xtime_lock);
+
+               return IRQ_HANDLED;
+       }
+       else
+               return IRQ_NONE;                /* not handled */
+}
+
+static struct irqaction at91rm9200_timer_irq = {
+       .name           = "at91_tick",
+       .flags          = IRQF_SHARED | IRQF_DISABLED | IRQF_TIMER,
+       .handler        = at91rm9200_timer_interrupt
+};
+
+void at91rm9200_timer_reset(void)
+{
+       last_crtr = 0;
+
+       /* Real time counter incremented every 30.51758 microseconds */
+       at91_sys_write(AT91_ST_RTMR, 1);
+
+       /* Set Period Interval timer */
+       at91_sys_write(AT91_ST_PIMR, LATCH);
+
+       /* Enable Period Interval Timer interrupt */
+       at91_sys_write(AT91_ST_IER, AT91_ST_PITS);
+}
+
+/*
+ * Set up timer interrupt.
+ */
+void __init at91rm9200_timer_init(void)
+{
+       /* Disable all timer interrupts */
+       at91_sys_write(AT91_ST_IDR, AT91_ST_PITS | AT91_ST_WDOVF | AT91_ST_RTTINC | AT91_ST_ALMS);
+       (void) at91_sys_read(AT91_ST_SR);       /* Clear any pending interrupts */
+
+       /* Make IRQs happen for the system timer */
+       setup_irq(AT91_ID_SYS, &at91rm9200_timer_irq);
+
+       /* Change the kernel's 'tick' value to 10009 usec. (the default is 10000) */
+       tick_usec = (LATCH * 1000000) / CLOCK_TICK_RATE;
+
+       /* Initialize and enable the timer interrupt */
+       at91rm9200_timer_reset();
+}
+
+#ifdef CONFIG_PM
+static void at91rm9200_timer_suspend(void)
+{
+       /* disable Period Interval Timer interrupt */
+       at91_sys_write(AT91_ST_IDR, AT91_ST_PITS);
+}
+#else
+#define at91rm9200_timer_suspend       NULL
+#endif
+
+struct sys_timer at91rm9200_timer = {
+       .init           = at91rm9200_timer_init,
+       .offset         = at91rm9200_gettimeoffset,
+       .suspend        = at91rm9200_timer_suspend,
+       .resume         = at91rm9200_timer_reset,
+};
+