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authorSAN People <andrew@sanpeople.com>2006-01-09 17:05:41 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2006-01-09 17:05:41 +0000
commit73a59c1c4af06c675a168d698d3ebfbb3270ddbe (patch)
treefa1708e19cf89a6bd13c8f7725a9cc67cc4ae6fd /arch/arm/mach-at91rm9200/time.c
parent50365c57860cd931c2d806057e0987634797e9af (diff)
downloadlinux-2.6.34-ux500-73a59c1c4af06c675a168d698d3ebfbb3270ddbe.tar.gz
[ARM] 3240/2: AT91RM9200 support for 2.6 (Core)
Patch from SAN People Following changes were made to clock.c: 1) Replaced <asm/hardware/clock.h> with <linux/clk.h> 2) Removed old unused clk_enable & clk_disable. 3) Replaced clk_use/clk_unuse with clk_enable/clk_disable. Otherwise it's the same as the previous patch. Signed-off-by: Andrew Victor <andrew@sanpeople.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mach-at91rm9200/time.c')
-rw-r--r--arch/arm/mach-at91rm9200/time.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/arch/arm/mach-at91rm9200/time.c b/arch/arm/mach-at91rm9200/time.c
new file mode 100644
index 00000000000..1b6dd2deeb2
--- /dev/null
+++ b/arch/arm/mach-at91rm9200/time.c
@@ -0,0 +1,127 @@
+/*
+ * linux/arch/arm/mach-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/config.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/mach/time.h>
+
+/*
+ * 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() - at91_sys_read(AT91_ST_RTAR)) & 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)
+{
+ unsigned long rtar;
+
+ if (at91_sys_read(AT91_ST_SR) & AT91_ST_PITS) { /* This is a shared interrupt */
+ write_seqlock(&xtime_lock);
+
+ do {
+ timer_tick(regs);
+ rtar = (at91_sys_read(AT91_ST_RTAR) + LATCH) & AT91_ST_ALMV;
+ at91_sys_write(AT91_ST_RTAR, rtar);
+ } while (((read_CRTR() - at91_sys_read(AT91_ST_RTAR)) & AT91_ST_ALMV) >= LATCH);
+
+ write_sequnlock(&xtime_lock);
+
+ return IRQ_HANDLED;
+ }
+ else
+ return IRQ_NONE; /* not handled */
+}
+
+static struct irqaction at91rm9200_timer_irq = {
+ .name = "at91_tick",
+ .flags = SA_SHIRQ | SA_INTERRUPT,
+ .handler = at91rm9200_timer_interrupt
+};
+
+/*
+ * 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);
+
+ /* Set initial alarm to 0 */
+ at91_sys_write(AT91_ST_RTAR, 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);
+
+ /* Change the kernel's 'tick' value to 10009 usec. (the default is 10000) */
+ tick_usec = (LATCH * 1000000) / CLOCK_TICK_RATE;
+
+ /* Enable Period Interval Timer interrupt */
+ at91_sys_write(AT91_ST_IER, AT91_ST_PITS);
+}
+
+struct sys_timer at91rm9200_timer = {
+ .init = at91rm9200_timer_init,
+ .offset = at91rm9200_gettimeoffset,
+};