arm nomadik: use 1000 as HZ value and rewrite timer code
This sets CONFIG_SYS_HZ to 1000 as required, and completely rewrites
timer code, which is now both correct and much smaller. Unused
functions like udelay_masked() have been removed as no driver uses
them, even the ones that are not currently active for this board.
mtu.h is copied literally from the kernel sources.
Signed-off-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Andrea Gallo <andrea.gallo@stericsson.com>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/cpu/arm926ejs/nomadik/timer.c b/cpu/arm926ejs/nomadik/timer.c
index 2870d24..16067c9 100644
--- a/cpu/arm926ejs/nomadik/timer.c
+++ b/cpu/arm926ejs/nomadik/timer.c
@@ -1,20 +1,5 @@
/*
- * (C) Copyright 2003
- * Texas Instruments <www.ti.com>
- *
- * (C) Copyright 2002
- * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
- * Marius Groeger <mgroeger@sysgo.de>
- *
- * (C) Copyright 2002
- * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
- * Alex Zuepke <azu@sysgo.de>
- *
- * (C) Copyright 2002-2004
- * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
- *
- * (C) Copyright 2004
- * Philippe Robin, ARM Ltd. <philippe.robin@arm.com>
+ * (C) Copyright 2009 Alessandro Rubini
*
* See file CREDITS for list of people who contributed to this
* project.
@@ -37,146 +22,49 @@
#include <common.h>
#include <asm/io.h>
+#include <asm/arch/mtu.h>
-#define TIMER_LOAD_VAL 0xffffffff
+/*
+ * The timer is a decrementer, we'll left it free running at 2.4MHz.
+ * We have 2.4 ticks per microsecond and an overflow in almost 30min
+ */
+#define TIMER_CLOCK (24 * 100 * 1000)
+#define COUNT_TO_USEC(x) ((x) * 5 / 12) /* overflows at 6min */
+#define USEC_TO_COUNT(x) ((x) * 12 / 5) /* overflows at 6min */
+#define TICKS_PER_HZ (TIMER_CLOCK / CONFIG_SYS_HZ)
+#define TICKS_TO_HZ(x) ((x) / TICKS_PER_HZ)
-/* macro to read the 32 bit timer */
-#define READ_TIMER readl(CONFIG_SYS_TIMERBASE + 20)
+/* macro to read the 32 bit timer: since it decrements, we invert read value */
+#define READ_TIMER() (~readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0)))
-static ulong timestamp;
-static ulong lastdec;
-
-/* nothing really to do with interrupts, just starts up a counter. */
+/* Configure a free-running, auto-wrap counter with no prescaler */
int timer_init(void)
{
- /* Load timer with initial value */
- writel(TIMER_LOAD_VAL, CONFIG_SYS_TIMERBASE + 16);
-
- /*
- * Set timer to be enabled, free-running, no interrupts, 256 divider,
- * 32-bit, wrap-mode
- */
- writel(0x8a, CONFIG_SYS_TIMERBASE + 24);
-
- /* init the timestamp and lastdec value */
- reset_timer_masked();
-
+ writel(MTU_CRn_ENA | MTU_CRn_PRESCALE_1 | MTU_CRn_32BITS,
+ CONFIG_SYS_TIMERBASE + MTU_CR(0));
+ reset_timer();
return 0;
}
-/*
- * timer without interrupts
- */
+/* Restart counting from 0 */
void reset_timer(void)
{
- reset_timer_masked();
+ writel(0, CONFIG_SYS_TIMERBASE + MTU_LR(0)); /* Immediate effect */
}
+/* Return how many HZ passed since "base" */
ulong get_timer(ulong base)
{
- return get_timer_masked() - base;
+ return TICKS_TO_HZ(READ_TIMER()) - base;
}
-void set_timer(ulong t)
-{
- timestamp = t;
-}
-
-/* delay x useconds AND perserve advance timstamp value */
+/* Delay x useconds */
void udelay(unsigned long usec)
{
- ulong tmo, tmp;
+ ulong ini, end;
- if (usec >= 1000) {
- /* if "big" number, spread normalization to seconds */
- tmo = usec / 1000; /* start to normalize */
- tmo *= CONFIG_SYS_HZ; /* find number of "ticks" */
- tmo /= 1000; /* finish normalize. */
- } else {
- /* small number, don't kill it prior to HZ multiply */
- tmo = usec * CONFIG_SYS_HZ;
- tmo /= (1000 * 1000);
- }
-
- tmp = get_timer(0); /* get current timestamp */
- if ((tmo + tmp + 1) < tmp) /* will roll time stamp? */
- reset_timer_masked(); /* reset to 0, set lastdec value */
- else
- tmo += tmp;
-
- while (get_timer_masked() < tmo)
- /* nothing */ ;
-}
-
-void reset_timer_masked(void)
-{
- /* reset time */
- lastdec = READ_TIMER; /* capure current decrementer value time */
- timestamp = 0; /* start "advancing" time stamp from 0 */
-}
-
-ulong get_timer_masked(void)
-{
- ulong now = READ_TIMER; /* current tick value */
-
- if (lastdec >= now) { /* normal mode (non roll) */
- /* move stamp fordward */
- timestamp += lastdec - now;
- } else {
- /*
- * An overflow is expected.
- * nts = ts + ld + (TLV - now)
- * ts=old stamp, ld=time that passed before passing through -1
- * (TLV-now) amount of time after passing though -1
- * nts = new "advancing time stamp"...it could also roll
- */
- timestamp += lastdec + TIMER_LOAD_VAL - now;
- }
- lastdec = now;
-
- return timestamp;
-}
-
-/* waits specified delay value and resets timestamp */
-void udelay_masked(unsigned long usec)
-{
- ulong tmo;
-
- if (usec >= 1000) {
- /* if "big" number, spread normalization to seconds */
- tmo = usec / 1000; /* start to normalize */
- tmo *= CONFIG_SYS_HZ; /* find number of "ticks" */
- tmo /= 1000; /* finish normalize. */
- } else {
- /* else small number, don't kill it prior to HZ multiply */
- tmo = usec * CONFIG_SYS_HZ;
- tmo /= (1000*1000);
- }
-
- reset_timer_masked();
- /* set "advancing" timestamp to 0, set lastdec vaule */
-
- while (get_timer_masked() < tmo)
- /* nothing */ ;
-}
-
-/*
- * This function is derived from PowerPC code (read timebase as long long).
- * On ARM it just returns the timer value.
- */
-unsigned long long get_ticks(void)
-{
- return get_timer(0);
-}
-
-/*
- * This function is derived from PowerPC code (timebase clock frequency).
- * On ARM it returns the number of timer ticks per second.
- */
-ulong get_tbclk(void)
-{
- ulong tbclk;
-
- tbclk = CONFIG_SYS_HZ;
- return tbclk;
+ ini = READ_TIMER();
+ end = ini + USEC_TO_COUNT(usec);
+ while ((signed)(end - READ_TIMER()) > 0)
+ ;
}