cpu/arm720t/interrupts.c - platform/external/u-boot - Gitiles

 /*
  * (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>
  *
  * See file CREDITS for list of people who contributed to this
  * project.
  *
  * 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 <common.h>
 #include <clps7111.h>
 #include <asm/proc-armv/ptrace.h>
 #include <asm/hardware.h>

 #ifndef CONFIG_NETARM
 /* we always count down the max. */
 #define TIMER_LOAD_VAL 0xffff
 /* macro to read the 16 bit timer */
 #define READ_TIMER (IO_TC1D & 0xffff)
 #else
 #define IRQEN	(*(volatile unsigned int *)(NETARM_GEN_MODULE_BASE + NETARM_GEN_INTR_ENABLE))
 #define TM2CTRL (*(volatile unsigned int *)(NETARM_GEN_MODULE_BASE + NETARM_GEN_TIMER2_CONTROL))
 #define TM2STAT (*(volatile unsigned int *)(NETARM_GEN_MODULE_BASE + NETARM_GEN_TIMER2_STATUS))
 #define TIMER_LOAD_VAL NETARM_GEN_TSTAT_CTC_MASK
 #define READ_TIMER (TM2STAT & NETARM_GEN_TSTAT_CTC_MASK)
 #endif

 #ifdef CONFIG_S3C4510B
 /* require interrupts for the S3C4510B */
 # ifndef CONFIG_USE_IRQ
 #  error CONFIG_USE_IRQ _must_ be defined when using CONFIG_S3C4510B
 # else
 static struct _irq_handler IRQ_HANDLER[N_IRQS];
 # endif
 #endif	/* CONFIG_S3C4510B */

 #ifdef CONFIG_USE_IRQ
 /* enable IRQ/FIQ interrupts */
 void enable_interrupts (void)
 {
 	unsigned long temp;
 	__asm__ __volatile__("mrs %0, cpsr\n"
 			     "bic %0, %0, #0x80\n"
 			     "msr cpsr_c, %0"
 			     : "=r" (temp)
 			     :
 			     : "memory");
 }


 /*
  * disable IRQ/FIQ interrupts
  * returns true if interrupts had been enabled before we disabled them
  */
 int disable_interrupts (void)
 {
 	unsigned long old,temp;
 	__asm__ __volatile__("mrs %0, cpsr\n"
 			     "orr %1, %0, #0x80\n"
 			     "msr cpsr_c, %1"
 			     : "=r" (old), "=r" (temp)
 			     :
 			     : "memory");
 	return (old & 0x80) == 0;
 }
 #else /* CONFIG_USE_IRQ */
 void enable_interrupts (void)
 {
 	return;
 }
 int disable_interrupts (void)
 {
 	return 0;
 }
 #endif

 void bad_mode (void)
 {
 	panic ("Resetting CPU ...\n");
 	reset_cpu (0);
 }

 void show_regs (struct pt_regs *regs)
 {
 	unsigned long flags;
 	const char *processor_modes[] =
 		{ "USER_26", "FIQ_26", "IRQ_26", "SVC_26", "UK4_26", "UK5_26",
 "UK6_26", "UK7_26",
 		"UK8_26", "UK9_26", "UK10_26", "UK11_26", "UK12_26", "UK13_26",
 				"UK14_26", "UK15_26",
 		"USER_32", "FIQ_32", "IRQ_32", "SVC_32", "UK4_32", "UK5_32",
 				"UK6_32", "ABT_32",
 		"UK8_32", "UK9_32", "UK10_32", "UND_32", "UK12_32", "UK13_32",
 				"UK14_32", "SYS_32"
 	};

 	flags = condition_codes (regs);

 	printf ("pc : [<%08lx>]	   lr : [<%08lx>]\n"
 			"sp : %08lx  ip : %08lx	 fp : %08lx\n",
 			instruction_pointer (regs),
 			regs->ARM_lr, regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
 	printf ("r10: %08lx  r9 : %08lx	 r8 : %08lx\n",
 			regs->ARM_r10, regs->ARM_r9, regs->ARM_r8);
 	printf ("r7 : %08lx  r6 : %08lx	 r5 : %08lx  r4 : %08lx\n",
 			regs->ARM_r7, regs->ARM_r6, regs->ARM_r5, regs->ARM_r4);
 	printf ("r3 : %08lx  r2 : %08lx	 r1 : %08lx  r0 : %08lx\n",
 			regs->ARM_r3, regs->ARM_r2, regs->ARM_r1, regs->ARM_r0);
 	printf ("Flags: %c%c%c%c",
 			flags & CC_N_BIT ? 'N' : 'n',
 			flags & CC_Z_BIT ? 'Z' : 'z',
 			flags & CC_C_BIT ? 'C' : 'c', flags & CC_V_BIT ? 'V' : 'v');
 	printf ("  IRQs %s  FIQs %s  Mode %s%s\n",
 			interrupts_enabled (regs) ? "on" : "off",
 			fast_interrupts_enabled (regs) ? "on" : "off",
 			processor_modes[processor_mode (regs)],
 			thumb_mode (regs) ? " (T)" : "");
 }

 void do_undefined_instruction (struct pt_regs *pt_regs)
 {
 	printf ("undefined instruction\n");
 	show_regs (pt_regs);
 	bad_mode ();
 }

 void do_software_interrupt (struct pt_regs *pt_regs)
 {
 	printf ("software interrupt\n");
 	show_regs (pt_regs);
 	bad_mode ();
 }

 void do_prefetch_abort (struct pt_regs *pt_regs)
 {
 	printf ("prefetch abort\n");
 	show_regs (pt_regs);
 	bad_mode ();
 }

 void do_data_abort (struct pt_regs *pt_regs)
 {
 	printf ("data abort\n");
 	show_regs (pt_regs);
 	bad_mode ();
 }

 void do_not_used (struct pt_regs *pt_regs)
 {
 	printf ("not used\n");
 	show_regs (pt_regs);
 	bad_mode ();
 }

 void do_fiq (struct pt_regs *pt_regs)
 {
 	printf ("fast interrupt request\n");
 	show_regs (pt_regs);
 	bad_mode ();
 }

 void do_irq (struct pt_regs *pt_regs)
 {
 #if defined(CONFIG_IMPA7) || defined(CONFIG_EP7312) || defined(CONFIG_NETARM) || defined(CONFIG_ARMADILLO)
 	printf ("interrupt request\n");
 	show_regs (pt_regs);
 	bad_mode ();
 #elif defined(CONFIG_S3C4510B)
 	unsigned int pending;

 	while ( (pending = GET_REG( REG_INTOFFSET)) != 0x54) {  /* sentinal value for no pending interrutps */
 		IRQ_HANDLER[pending>>2].m_func( IRQ_HANDLER[pending>>2].m_data);

 		/* clear pending interrupt */
 		PUT_REG( REG_INTPEND, (1<<(pending>>2)));
 	}
 #else
 #error do_irq() not defined for this CPU type
 #endif
 }


 #ifdef CONFIG_S3C4510B
 static void default_isr( void *data) {
 	printf ("default_isr():  called for IRQ %d\n", (int)data);
 }

 static void timer_isr( void *data) {
 	unsigned int *pTime = (unsigned int *)data;

 	(*pTime)++;
 	if ( !(*pTime % (CFG_HZ/4))) {
 		/* toggle LED 0 */
 		PUT_REG( REG_IOPDATA, GET_REG(REG_IOPDATA) ^ 0x1);
 	}

 }
 #endif

 static ulong timestamp;
 static ulong lastdec;

 int interrupt_init (void)
 {

 #if defined(CONFIG_NETARM)
 	/* disable all interrupts */
 	IRQEN = 0;

 	/* operate timer 2 in non-prescale mode */
 	TM2CTRL = ( NETARM_GEN_TIMER_SET_HZ(CFG_HZ) |
 		    NETARM_GEN_TCTL_ENABLE |
 		    NETARM_GEN_TCTL_INIT_COUNT(TIMER_LOAD_VAL));

 	/* set timer 2 counter */
 	lastdec = TIMER_LOAD_VAL;
 #elif defined(CONFIG_IMPA7) || defined(CONFIG_EP7312) || defined(CONFIG_ARMADILLO)
 	/* disable all interrupts */
 	IO_INTMR1 = 0;

 	/* operate timer 1 in prescale mode */
 	IO_SYSCON1 |= SYSCON1_TC1M;

 	/* select 2kHz clock source for timer 1 */
 	IO_SYSCON1 &= ~SYSCON1_TC1S;

 	/* set timer 1 counter */
 	lastdec = IO_TC1D = TIMER_LOAD_VAL;
 #elif defined(CONFIG_S3C4510B)
 	int i;

 	/* install default interrupt handlers */
 	for ( i = 0; i < N_IRQS; i++) {
 		IRQ_HANDLER[i].m_data = (void *)i;
 		IRQ_HANDLER[i].m_func = default_isr;
 	}

 	/* configure interrupts for IRQ mode */
 	PUT_REG( REG_INTMODE, 0x0);
 	/* clear any pending interrupts */
 	PUT_REG( REG_INTPEND, 0x1FFFFF);

 	lastdec = 0;

 	/* install interrupt handler for timer */
 	IRQ_HANDLER[INT_TIMER0].m_data = (void *)&timestamp;
 	IRQ_HANDLER[INT_TIMER0].m_func = timer_isr;

 	/* configure free running timer 0 */
 	PUT_REG( REG_TMOD, 0x0);
 	/* Stop timer 0 */
 	CLR_REG( REG_TMOD, TM0_RUN);

 	/* Configure for interval mode */
 	CLR_REG( REG_TMOD, TM1_TOGGLE);

 	/*
 	 * Load Timer data register with count down value.
 	 * count_down_val = CFG_SYS_CLK_FREQ/CFG_HZ
 	 */
 	PUT_REG( REG_TDATA0, (CFG_SYS_CLK_FREQ / CFG_HZ));

 	/*
 	 * Enable global interrupt
 	 * Enable timer0 interrupt
 	 */
 	CLR_REG( REG_INTMASK, ((1<<INT_GLOBAL) | (1<<INT_TIMER0)));

 	/* Start timer */
 	SET_REG( REG_TMOD, TM0_RUN);

 #else
 #error No interrupt_init() defined for this CPU type
 #endif
 	timestamp = 0;

 	return (0);
 }

 /*
  * timer without interrupts
  */


 #if defined(CONFIG_IMPA7) || defined(CONFIG_EP7312) || defined(CONFIG_NETARM) || defined(CONFIG_ARMADILLO)

 void reset_timer (void)
 {
 	reset_timer_masked ();
 }

 ulong get_timer (ulong base)
 {
 	return get_timer_masked () - base;
 }

 void set_timer (ulong t)
 {
 	timestamp = t;
 }

 void udelay (unsigned long usec)
 {
 	ulong tmo;

 	tmo = usec / 1000;
 	tmo *= CFG_HZ;
 	tmo /= 1000;

 	tmo += get_timer (0);

 	while (get_timer_masked () < tmo)
 		/*NOP*/;
 }

 void reset_timer_masked (void)
 {
 	/* reset time */
 	lastdec = READ_TIMER;
 	timestamp = 0;
 }

 ulong get_timer_masked (void)
 {
 	ulong now = READ_TIMER;

 	if (lastdec >= now) {
 		/* normal mode */
 		timestamp += lastdec - now;
 	} else {
 		/* we have an overflow ... */
 		timestamp += lastdec + TIMER_LOAD_VAL - now;
 	}
 	lastdec = now;

 	return timestamp;
 }

 void udelay_masked (unsigned long usec)
 {
 	ulong tmo;
 	ulong endtime;
 	signed long diff;

 	if (usec >= 1000) {
 		tmo = usec / 1000;
 		tmo *= CFG_HZ;
 		tmo /= 1000;
 	} else {
 		tmo = usec * CFG_HZ;
 		tmo /= (1000*1000);
 	}

 	endtime = get_timer_masked () + tmo;

 	do {
 		ulong now = get_timer_masked ();
 		diff = endtime - now;
 	} while (diff >= 0);
 }

 #elif defined(CONFIG_S3C4510B)

 ulong get_timer (ulong base)
 {
 	return timestamp - base;
 }

 void udelay (unsigned long usec)
 {
 	u32 ticks;

 	ticks = (usec * CFG_HZ) / 1000000;

 	ticks += get_timer (0);

 	while (get_timer (0) < ticks)
 		/*NOP*/;

 }

 #else
 #error Timer routines not defined for this CPU type
 #endif
	/*
	* (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>
	*
	* See file CREDITS for list of people who contributed to this
	* project.
	*
	* 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 <common.h>
	#include <clps7111.h>
	#include <asm/proc-armv/ptrace.h>
	#include <asm/hardware.h>

	#ifndef CONFIG_NETARM
	/* we always count down the max. */
	#define TIMER_LOAD_VAL 0xffff
	/* macro to read the 16 bit timer */
	#define READ_TIMER (IO_TC1D & 0xffff)
	#else
	#define IRQEN ((volatile unsigned int )(NETARM_GEN_MODULE_BASE + NETARM_GEN_INTR_ENABLE))
	#define TM2CTRL ((volatile unsigned int )(NETARM_GEN_MODULE_BASE + NETARM_GEN_TIMER2_CONTROL))
	#define TM2STAT ((volatile unsigned int )(NETARM_GEN_MODULE_BASE + NETARM_GEN_TIMER2_STATUS))
	#define TIMER_LOAD_VAL NETARM_GEN_TSTAT_CTC_MASK
	#define READ_TIMER (TM2STAT & NETARM_GEN_TSTAT_CTC_MASK)
	#endif

	#ifdef CONFIG_S3C4510B
	/* require interrupts for the S3C4510B */
	# ifndef CONFIG_USE_IRQ
	# error CONFIG_USE_IRQ _must_ be defined when using CONFIG_S3C4510B
	# else
	static struct _irq_handler IRQ_HANDLER[N_IRQS];
	# endif
	#endif /* CONFIG_S3C4510B */

	#ifdef CONFIG_USE_IRQ
	/* enable IRQ/FIQ interrupts */
	void enable_interrupts (void)
	{
	unsigned long temp;
	__asm__ __volatile__("mrs %0, cpsr\n"
	"bic %0, %0, #0x80\n"
	"msr cpsr_c, %0"
	: "=r" (temp)
	:
	: "memory");
	}


	/*
	* disable IRQ/FIQ interrupts
	* returns true if interrupts had been enabled before we disabled them
	*/
	int disable_interrupts (void)
	{
	unsigned long old,temp;
	__asm__ __volatile__("mrs %0, cpsr\n"
	"orr %1, %0, #0x80\n"
	"msr cpsr_c, %1"
	: "=r" (old), "=r" (temp)
	:
	: "memory");
	return (old & 0x80) == 0;
	}
	#else /* CONFIG_USE_IRQ */
	void enable_interrupts (void)
	{
	return;
	}
	int disable_interrupts (void)
	{
	return 0;
	}
	#endif

	void bad_mode (void)
	{
	panic ("Resetting CPU ...\n");
	reset_cpu (0);
	}

	void show_regs (struct pt_regs *regs)
	{
	unsigned long flags;
	const char *processor_modes[] =
	{ "USER_26", "FIQ_26", "IRQ_26", "SVC_26", "UK4_26", "UK5_26",
	"UK6_26", "UK7_26",
	"UK8_26", "UK9_26", "UK10_26", "UK11_26", "UK12_26", "UK13_26",
	"UK14_26", "UK15_26",
	"USER_32", "FIQ_32", "IRQ_32", "SVC_32", "UK4_32", "UK5_32",
	"UK6_32", "ABT_32",
	"UK8_32", "UK9_32", "UK10_32", "UND_32", "UK12_32", "UK13_32",
	"UK14_32", "SYS_32"
	};

	flags = condition_codes (regs);

	printf ("pc : [<%08lx>] lr : [<%08lx>]\n"
	"sp : %08lx ip : %08lx fp : %08lx\n",
	instruction_pointer (regs),
	regs->ARM_lr, regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
	printf ("r10: %08lx r9 : %08lx r8 : %08lx\n",
	regs->ARM_r10, regs->ARM_r9, regs->ARM_r8);
	printf ("r7 : %08lx r6 : %08lx r5 : %08lx r4 : %08lx\n",
	regs->ARM_r7, regs->ARM_r6, regs->ARM_r5, regs->ARM_r4);
	printf ("r3 : %08lx r2 : %08lx r1 : %08lx r0 : %08lx\n",
	regs->ARM_r3, regs->ARM_r2, regs->ARM_r1, regs->ARM_r0);
	printf ("Flags: %c%c%c%c",
	flags & CC_N_BIT ? 'N' : 'n',
	flags & CC_Z_BIT ? 'Z' : 'z',
	flags & CC_C_BIT ? 'C' : 'c', flags & CC_V_BIT ? 'V' : 'v');
	printf (" IRQs %s FIQs %s Mode %s%s\n",
	interrupts_enabled (regs) ? "on" : "off",
	fast_interrupts_enabled (regs) ? "on" : "off",
	processor_modes[processor_mode (regs)],
	thumb_mode (regs) ? " (T)" : "");
	}

	void do_undefined_instruction (struct pt_regs *pt_regs)
	{
	printf ("undefined instruction\n");
	show_regs (pt_regs);
	bad_mode ();
	}

	void do_software_interrupt (struct pt_regs *pt_regs)
	{
	printf ("software interrupt\n");
	show_regs (pt_regs);
	bad_mode ();
	}

	void do_prefetch_abort (struct pt_regs *pt_regs)
	{
	printf ("prefetch abort\n");
	show_regs (pt_regs);
	bad_mode ();
	}

	void do_data_abort (struct pt_regs *pt_regs)
	{
	printf ("data abort\n");
	show_regs (pt_regs);
	bad_mode ();
	}

	void do_not_used (struct pt_regs *pt_regs)
	{
	printf ("not used\n");
	show_regs (pt_regs);
	bad_mode ();
	}

	void do_fiq (struct pt_regs *pt_regs)
	{
	printf ("fast interrupt request\n");
	show_regs (pt_regs);
	bad_mode ();
	}

	void do_irq (struct pt_regs *pt_regs)
	{
	#if defined(CONFIG_IMPA7) \|\| defined(CONFIG_EP7312) \|\| defined(CONFIG_NETARM) \|\| defined(CONFIG_ARMADILLO)
	printf ("interrupt request\n");
	show_regs (pt_regs);
	bad_mode ();
	#elif defined(CONFIG_S3C4510B)
	unsigned int pending;

	while ( (pending = GET_REG( REG_INTOFFSET)) != 0x54) { /* sentinal value for no pending interrutps */
	IRQ_HANDLER[pending>>2].m_func( IRQ_HANDLER[pending>>2].m_data);

	/* clear pending interrupt */
	PUT_REG( REG_INTPEND, (1<<(pending>>2)));
	}
	#else
	#error do_irq() not defined for this CPU type
	#endif
	}


	#ifdef CONFIG_S3C4510B
	static void default_isr( void *data) {
	printf ("default_isr(): called for IRQ %d\n", (int)data);
	}

	static void timer_isr( void *data) {
	unsigned int pTime = (unsigned int )data;

	(*pTime)++;
	if ( !(*pTime % (CFG_HZ/4))) {
	/* toggle LED 0 */
	PUT_REG( REG_IOPDATA, GET_REG(REG_IOPDATA) ^ 0x1);
	}

	}
	#endif

	static ulong timestamp;
	static ulong lastdec;

	int interrupt_init (void)
	{

	#if defined(CONFIG_NETARM)
	/* disable all interrupts */
	IRQEN = 0;

	/* operate timer 2 in non-prescale mode */
	TM2CTRL = ( NETARM_GEN_TIMER_SET_HZ(CFG_HZ) \|
	NETARM_GEN_TCTL_ENABLE \|
	NETARM_GEN_TCTL_INIT_COUNT(TIMER_LOAD_VAL));

	/* set timer 2 counter */
	lastdec = TIMER_LOAD_VAL;
	#elif defined(CONFIG_IMPA7) \|\| defined(CONFIG_EP7312) \|\| defined(CONFIG_ARMADILLO)
	/* disable all interrupts */
	IO_INTMR1 = 0;

	/* operate timer 1 in prescale mode */
	IO_SYSCON1 \|= SYSCON1_TC1M;

	/* select 2kHz clock source for timer 1 */
	IO_SYSCON1 &= ~SYSCON1_TC1S;

	/* set timer 1 counter */
	lastdec = IO_TC1D = TIMER_LOAD_VAL;
	#elif defined(CONFIG_S3C4510B)
	int i;

	/* install default interrupt handlers */
	for ( i = 0; i < N_IRQS; i++) {
	IRQ_HANDLER[i].m_data = (void *)i;
	IRQ_HANDLER[i].m_func = default_isr;
	}

	/* configure interrupts for IRQ mode */
	PUT_REG( REG_INTMODE, 0x0);
	/* clear any pending interrupts */
	PUT_REG( REG_INTPEND, 0x1FFFFF);

	lastdec = 0;

	/* install interrupt handler for timer */
	IRQ_HANDLER[INT_TIMER0].m_data = (void *)&timestamp;
	IRQ_HANDLER[INT_TIMER0].m_func = timer_isr;

	/* configure free running timer 0 */
	PUT_REG( REG_TMOD, 0x0);
	/* Stop timer 0 */
	CLR_REG( REG_TMOD, TM0_RUN);

	/* Configure for interval mode */
	CLR_REG( REG_TMOD, TM1_TOGGLE);

	/*
	* Load Timer data register with count down value.
	* count_down_val = CFG_SYS_CLK_FREQ/CFG_HZ
	*/
	PUT_REG( REG_TDATA0, (CFG_SYS_CLK_FREQ / CFG_HZ));

	/*
	* Enable global interrupt
	* Enable timer0 interrupt
	*/
	CLR_REG( REG_INTMASK, ((1<<INT_GLOBAL) \| (1<<INT_TIMER0)));

	/* Start timer */
	SET_REG( REG_TMOD, TM0_RUN);

	#else
	#error No interrupt_init() defined for this CPU type
	#endif
	timestamp = 0;

	return (0);
	}

	/*
	* timer without interrupts
	*/


	#if defined(CONFIG_IMPA7) \|\| defined(CONFIG_EP7312) \|\| defined(CONFIG_NETARM) \|\| defined(CONFIG_ARMADILLO)

	void reset_timer (void)
	{
	reset_timer_masked ();
	}

	ulong get_timer (ulong base)
	{
	return get_timer_masked () - base;
	}

	void set_timer (ulong t)
	{
	timestamp = t;
	}

	void udelay (unsigned long usec)
	{
	ulong tmo;

	tmo = usec / 1000;
	tmo *= CFG_HZ;
	tmo /= 1000;

	tmo += get_timer (0);

	while (get_timer_masked () < tmo)
	/NOP/;
	}

	void reset_timer_masked (void)
	{
	/* reset time */
	lastdec = READ_TIMER;
	timestamp = 0;
	}

	ulong get_timer_masked (void)
	{
	ulong now = READ_TIMER;

	if (lastdec >= now) {
	/* normal mode */
	timestamp += lastdec - now;
	} else {
	/* we have an overflow ... */
	timestamp += lastdec + TIMER_LOAD_VAL - now;
	}
	lastdec = now;

	return timestamp;
	}

	void udelay_masked (unsigned long usec)
	{
	ulong tmo;
	ulong endtime;
	signed long diff;

	if (usec >= 1000) {
	tmo = usec / 1000;
	tmo *= CFG_HZ;
	tmo /= 1000;
	} else {
	tmo = usec * CFG_HZ;
	tmo /= (1000*1000);
	}

	endtime = get_timer_masked () + tmo;

	do {
	ulong now = get_timer_masked ();
	diff = endtime - now;
	} while (diff >= 0);
	}

	#elif defined(CONFIG_S3C4510B)

	ulong get_timer (ulong base)
	{
	return timestamp - base;
	}

	void udelay (unsigned long usec)
	{
	u32 ticks;

	ticks = (usec * CFG_HZ) / 1000000;

	ticks += get_timer (0);

	while (get_timer (0) < ticks)
	/NOP/;

	}

	#else
	#error Timer routines not defined for this CPU type
	#endif