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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm/mach-imx/time.c
downloadlinux-stericsson-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/arm/mach-imx/time.c')
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1 files changed, 101 insertions, 0 deletions
diff --git a/arch/arm/mach-imx/time.c b/arch/arm/mach-imx/time.c
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+/*
+ * linux/arch/arm/mach-imx/time.c
+ *
+ * Copyright (C) 2000-2001 Deep Blue Solutions
+ * Copyright (C) 2002 Shane Nay (shane@minirl.com)
+ *
+ * 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/config.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/time.h>
+
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/leds.h>
+#include <asm/irq.h>
+#include <asm/mach/time.h>
+
+/* Use timer 1 as system timer */
+#define TIMER_BASE IMX_TIM1_BASE
+
+/*
+ * Returns number of us since last clock interrupt. Note that interrupts
+ * will have been disabled by do_gettimeoffset()
+ */
+static unsigned long imx_gettimeoffset(void)
+{
+ unsigned long ticks;
+
+ /*
+ * Get the current number of ticks. Note that there is a race
+ * condition between us reading the timer and checking for
+ * an interrupt. We get around this by ensuring that the
+ * counter has not reloaded between our two reads.
+ */
+ ticks = IMX_TCN(TIMER_BASE);
+
+ /*
+ * Interrupt pending? If so, we've reloaded once already.
+ */
+ if (IMX_TSTAT(TIMER_BASE) & TSTAT_COMP)
+ ticks += LATCH;
+
+ /*
+ * Convert the ticks to usecs
+ */
+ return (1000000 / CLK32) * ticks;
+}
+
+/*
+ * IRQ handler for the timer
+ */
+static irqreturn_t
+imx_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ write_seqlock(&xtime_lock);
+
+ /* clear the interrupt */
+ if (IMX_TSTAT(TIMER_BASE))
+ IMX_TSTAT(TIMER_BASE) = 0;
+
+ timer_tick(regs);
+ write_sequnlock(&xtime_lock);
+
+ return IRQ_HANDLED;
+}
+
+static struct irqaction imx_timer_irq = {
+ .name = "i.MX Timer Tick",
+ .flags = SA_INTERRUPT,
+ .handler = imx_timer_interrupt
+};
+
+/*
+ * Set up timer interrupt, and return the current time in seconds.
+ */
+static void __init imx_timer_init(void)
+{
+ /*
+ * Initialise to a known state (all timers off, and timing reset)
+ */
+ IMX_TCTL(TIMER_BASE) = 0;
+ IMX_TPRER(TIMER_BASE) = 0;
+ IMX_TCMP(TIMER_BASE) = LATCH - 1;
+ IMX_TCTL(TIMER_BASE) = TCTL_CLK_32 | TCTL_IRQEN | TCTL_TEN;
+
+ /*
+ * Make irqs happen for the system timer
+ */
+ setup_irq(TIM1_INT, &imx_timer_irq);
+}
+
+struct sys_timer imx_timer = {
+ .init = imx_timer_init,
+ .offset = imx_gettimeoffset,
+};