examples/standalone/timer.c - github/trini/u-boot - Gitiles

 /*
  * (C) Copyright 2000
  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */

 #include <common.h>
 #include <commproc.h>
 #include <mpc8xx_irq.h>
 #include <exports.h>

 DECLARE_GLOBAL_DATA_PTR;

 #undef	DEBUG

 #define	TIMER_PERIOD	1000000		/* 1 second clock */

 static void timer_handler (void *arg);


 /* Access functions for the Machine State Register */
 static __inline__ unsigned long get_msr(void)
 {
     unsigned long msr;

     asm volatile("mfmsr %0" : "=r" (msr) :);
     return msr;
 }

 static __inline__ void set_msr(unsigned long msr)
 {
     asm volatile("mtmsr %0" : : "r" (msr));
 }

 /*
  * Definitions to access the CPM Timer registers
  * See 8xx_immap.h for Internal Memory Map layout,
  * and commproc.h for CPM Interrupt vectors (aka "IRQ"s)
  */

 typedef struct tid_8xx_cpmtimer_s {
   int		 cpm_vec;	/* CPM Interrupt Vector for this timer	*/
   ushort	*tgcrp;		/* Pointer to Timer Global Config Reg.	*/
   ushort	*tmrp;		/* Pointer to Timer Mode Register	*/
   ushort	*trrp;		/* Pointer to Timer Reference Register	*/
   ushort	*tcrp;		/* Pointer to Timer Capture Register	*/
   ushort	*tcnp;		/* Pointer to Timer Counter Register	*/
   ushort	*terp;		/* Pointer to Timer Event Register	*/
 } tid_8xx_cpmtimer_t;

 #ifndef CLOCKRATE
 #  define CLOCKRATE 64
 #endif

 #define	CPMT_CLOCK_DIV		16
 #define	CPMT_MAX_PRESCALER	256
 #define CPMT_MAX_REFERENCE	65535	/* max. unsigned short */

 #define	CPMT_MAX_TICKS		(CPMT_MAX_REFERENCE * CPMT_MAX_PRESCALER)
 #define	CPMT_MAX_TICKS_WITH_DIV	(CPMT_MAX_REFERENCE * CPMT_MAX_PRESCALER * CPMT_CLOCK_DIV)
 #define	CPMT_MAX_INTERVAL	(CPMT_MAX_TICKS_WITH_DIV / CLOCKRATE)

 /* For now: always use max. prescaler value */
 #define	CPMT_PRESCALER		(CPMT_MAX_PRESCALER)

 /* CPM Timer Event Register Bits */
 #define	CPMT_EVENT_CAP		0x0001	/* Capture Event		*/
 #define	CPMT_EVENT_REF		0x0002	/* Reference Counter Event	*/

 /* CPM Timer Global Config Register */
 #define	CPMT_GCR_RST		0x0001	/* Reset  Timer			*/
 #define	CPMT_GCR_STP		0x0002	/* Stop   Timer			*/
 #define	CPMT_GCR_FRZ		0x0004	/* Freeze Timer			*/
 #define	CPMT_GCR_GM_CAS		0x0008	/* Gate Mode / Cascade Timers	*/
 #define	CPMT_GCR_MASK		(CPMT_GCR_RST|CPMT_GCR_STP|CPMT_GCR_FRZ|CPMT_GCR_GM_CAS)

 /* CPM Timer Mode register */
 #define	CPMT_MR_GE		0x0001	/* Gate Enable			*/
 #define	CPMT_MR_ICLK_CASC	0x0000	/* Clock internally cascaded	*/
 #define	CPMT_MR_ICLK_CLK	0x0002	/* Clock = system clock		*/
 #define	CPMT_MR_ICLK_CLKDIV	0x0004	/* Clock = system clock / 16	*/
 #define	CPMT_MR_ICLK_TIN	0x0006	/* Clock = TINx signal		*/
 #define	CPMT_MR_FRR		0x0008	/* Free Run / Restart		*/
 #define	CPMT_MR_ORI		0x0010	/* Out. Reference Interrupt En.	*/
 #define	CPMT_MR_OM		0x0020	/* Output Mode			*/
 #define	CPMT_MR_CE_DIS		0x0000	/* Capture/Interrupt disabled	*/
 #define	CPMT_MR_CE_RISE		0x0040	/* Capt./Interr. on rising  TIN	*/
 #define CPMT_MR_CE_FALL		0x0080	/* Capt./Interr. on falling TIN	*/
 #define	CPMT_MR_CE_ANY		0x00C0	/* Capt./Interr. on any TIN edge*/


 /*
  * which CPM timer to use - index starts at 0 (= timer 1)
  */
 #define	TID_TIMER_ID	0	/* use CPM timer 1		*/

 void setPeriod (tid_8xx_cpmtimer_t *hwp, ulong interval);

 static const char usage[] = "\n[q, b, e, ?] ";

 int timer (int argc, char * const argv[])
 {
 	cpmtimer8xx_t *cpmtimerp;	/* Pointer to the CPM Timer structure   */
 	tid_8xx_cpmtimer_t hw;
 	tid_8xx_cpmtimer_t *hwp = &hw;
 	int c;
 	int running;

 	app_startup(argv);

 	/* Pointer to CPM Timer structure */
 	cpmtimerp = &((immap_t *) gd->bd->bi_immr_base)->im_cpmtimer;

 	printf ("TIMERS=0x%x\n", (unsigned) cpmtimerp);

 	/* Initialize pointers depending on which timer we use */
 	switch (TID_TIMER_ID) {
 	case 0:
 		hwp->tmrp = &(cpmtimerp->cpmt_tmr1);
 		hwp->trrp = &(cpmtimerp->cpmt_trr1);
 		hwp->tcrp = &(cpmtimerp->cpmt_tcr1);
 		hwp->tcnp = &(cpmtimerp->cpmt_tcn1);
 		hwp->terp = &(cpmtimerp->cpmt_ter1);
 		hwp->cpm_vec = CPMVEC_TIMER1;
 		break;
 	case 1:
 		hwp->tmrp = &(cpmtimerp->cpmt_tmr2);
 		hwp->trrp = &(cpmtimerp->cpmt_trr2);
 		hwp->tcrp = &(cpmtimerp->cpmt_tcr2);
 		hwp->tcnp = &(cpmtimerp->cpmt_tcn2);
 		hwp->terp = &(cpmtimerp->cpmt_ter2);
 		hwp->cpm_vec = CPMVEC_TIMER2;
 		break;
 	case 2:
 		hwp->tmrp = &(cpmtimerp->cpmt_tmr3);
 		hwp->trrp = &(cpmtimerp->cpmt_trr3);
 		hwp->tcrp = &(cpmtimerp->cpmt_tcr3);
 		hwp->tcnp = &(cpmtimerp->cpmt_tcn3);
 		hwp->terp = &(cpmtimerp->cpmt_ter3);
 		hwp->cpm_vec = CPMVEC_TIMER3;
 		break;
 	case 3:
 		hwp->tmrp = &(cpmtimerp->cpmt_tmr4);
 		hwp->trrp = &(cpmtimerp->cpmt_trr4);
 		hwp->tcrp = &(cpmtimerp->cpmt_tcr4);
 		hwp->tcnp = &(cpmtimerp->cpmt_tcn4);
 		hwp->terp = &(cpmtimerp->cpmt_ter4);
 		hwp->cpm_vec = CPMVEC_TIMER4;
 		break;
 	}

 	hwp->tgcrp = &cpmtimerp->cpmt_tgcr;

 	printf ("Using timer %d\n"
 			"tgcr @ 0x%x, tmr @ 0x%x, trr @ 0x%x,"
 			" tcr @ 0x%x, tcn @ 0x%x, ter @ 0x%x\n",
 			TID_TIMER_ID + 1,
 			(unsigned) hwp->tgcrp,
 			(unsigned) hwp->tmrp,
 			(unsigned) hwp->trrp,
 			(unsigned) hwp->tcrp,
 			(unsigned) hwp->tcnp,
 			(unsigned) hwp->terp
 			);

 	/* reset timer    */
 	*hwp->tgcrp &= ~(CPMT_GCR_MASK << TID_TIMER_ID);

 	/* clear all events */
 	*hwp->terp = (CPMT_EVENT_CAP | CPMT_EVENT_REF);

 	puts(usage);
 	running = 0;
 	while ((c = getc()) != 'q') {
 	    if (c == 'b') {

 		setPeriod (hwp, TIMER_PERIOD);	/* Set period and start ticking */

 		/* Install interrupt handler (enable timer in CIMR) */
 		install_hdlr (hwp->cpm_vec, timer_handler, hwp);

 		printf ("Enabling timer\n");

 		/* enable timer */
 		*hwp->tgcrp |= (CPMT_GCR_RST << TID_TIMER_ID);
 		running = 1;

 #ifdef	DEBUG
 		printf ("tgcr=0x%x, tmr=0x%x, trr=0x%x,"
 			" tcr=0x%x, tcn=0x%x, ter=0x%x\n",
 				*hwp->tgcrp, *hwp->tmrp, *hwp->trrp,
 				*hwp->tcrp,  *hwp->tcnp, *hwp->terp
 				);
 #endif
 	    } else if (c == 'e') {

 		printf ("Stopping timer\n");

 		*hwp->tgcrp &= ~(CPMT_GCR_MASK << TID_TIMER_ID);
 		running = 0;

 #ifdef	DEBUG
 		printf ("tgcr=0x%x, tmr=0x%x, trr=0x%x,"
 			" tcr=0x%x, tcn=0x%x, ter=0x%x\n",
 				*hwp->tgcrp, *hwp->tmrp, *hwp->trrp,
 				*hwp->tcrp,  *hwp->tcnp, *hwp->terp
 			);
 #endif
 		/* Uninstall interrupt handler */
 		free_hdlr (hwp->cpm_vec);

 	    } else if (c == '?') {
 #ifdef	DEBUG
 		cpic8xx_t *cpm_icp = &((immap_t *) gd->bd->bi_immr_base)->im_cpic;
 		sysconf8xx_t *siup = &((immap_t *) gd->bd->bi_immr_base)->im_siu_conf;
 #endif

 		printf ("\ntgcr=0x%x, tmr=0x%x, trr=0x%x,"
 			" tcr=0x%x, tcn=0x%x, ter=0x%x\n",
 				*hwp->tgcrp, *hwp->tmrp, *hwp->trrp,
 				*hwp->tcrp,  *hwp->tcnp, *hwp->terp
 			);
 #ifdef	DEBUG
 		printf ("SIUMCR=0x%08lx, SYPCR=0x%08lx,"
 			" SIMASK=0x%08lx, SIPEND=0x%08lx\n",
 				siup->sc_siumcr,
 				siup->sc_sypcr,
 				siup->sc_simask,
 				siup->sc_sipend
 			);

 		printf ("CIMR=0x%08lx, CICR=0x%08lx, CIPR=0x%08lx\n",
 			cpm_icp->cpic_cimr,
 			cpm_icp->cpic_cicr,
 			cpm_icp->cpic_cipr
 			);
 #endif
 	    } else {
 		printf ("\nEnter: q - quit, b - start timer, e - stop timer, ? - get status\n");
 	    }
 	    puts(usage);
 	}
 	if (running) {
 		printf ("Stopping timer\n");
 		*hwp->tgcrp &= ~(CPMT_GCR_MASK << TID_TIMER_ID);
 		free_hdlr (hwp->cpm_vec);
 	}

 	return (0);
 }


 /* Set period in microseconds and start.
  * Truncate to maximum period if more than this is requested - but warn about it.
  */

 void setPeriod (tid_8xx_cpmtimer_t *hwp, ulong interval)
 {
 	unsigned short prescaler;
 	unsigned long ticks;

 	printf ("Set interval %ld us\n", interval);

 	/* Warn if requesting longer period than possible */
 	if (interval > CPMT_MAX_INTERVAL) {
 		printf ("Truncate interval %ld to maximum (%d)\n",
 				interval, CPMT_MAX_INTERVAL);
 		interval = CPMT_MAX_INTERVAL;
 	}
 	/*
 	 * Check if we want to use clock divider:
 	 * Since the reference counter can be incremented only in integer steps,
 	 * we try to keep it as big as possible to allow the resulting period to be
 	 * as precise as possible.
 	 */
 	/* prescaler, enable interrupt, restart after ref count is reached */
 	prescaler = (ushort) ((CPMT_PRESCALER - 1) << 8) |
 			CPMT_MR_ORI |
 			CPMT_MR_FRR;

 	ticks = ((ulong) CLOCKRATE * interval);

 	if (ticks > CPMT_MAX_TICKS) {
 		ticks /= CPMT_CLOCK_DIV;
 		prescaler |= CPMT_MR_ICLK_CLKDIV;	/* use system clock divided by 16 */
 	} else {
 		prescaler |= CPMT_MR_ICLK_CLK;	/* use system clock without divider */
 	}

 #ifdef	DEBUG
 	printf ("clock/%d, prescale factor %d, reference %ld, ticks %ld\n",
 			(ticks > CPMT_MAX_TICKS) ? CPMT_CLOCK_DIV : 1,
 			CPMT_PRESCALER,
 			(ticks / CPMT_PRESCALER),
 			ticks
 			);
 #endif

 	/* set prescaler register */
 	*hwp->tmrp = prescaler;

 	/* clear timer counter */
 	*hwp->tcnp = 0;

 	/* set reference register */
 	*hwp->trrp = (unsigned short) (ticks / CPMT_PRESCALER);

 #ifdef	DEBUG
 	printf ("tgcr=0x%x, tmr=0x%x, trr=0x%x,"
 		" tcr=0x%x, tcn=0x%x, ter=0x%x\n",
 			*hwp->tgcrp, *hwp->tmrp, *hwp->trrp,
 			*hwp->tcrp,  *hwp->tcnp, *hwp->terp
 		);
 #endif
 }

 /*
  * Handler for CPMVEC_TIMER1 interrupt
  */
 static
 void timer_handler (void *arg)
 {
 	tid_8xx_cpmtimer_t *hwp = (tid_8xx_cpmtimer_t *)arg;

 	/* printf ("** TER1=%04x ** ", *hwp->terp); */

 	/* just for demonstration */
 	printf (".");

 	/* clear all possible events: Ref. and Cap. */
 	*hwp->terp = (CPMT_EVENT_CAP | CPMT_EVENT_REF);
 }
	/*
	* (C) Copyright 2000
	* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#include <common.h>
	#include <commproc.h>
	#include <mpc8xx_irq.h>
	#include <exports.h>

	DECLARE_GLOBAL_DATA_PTR;

	#undef DEBUG

	#define TIMER_PERIOD 1000000 /* 1 second clock */

	static void timer_handler (void *arg);


	/* Access functions for the Machine State Register */
	static __inline__ unsigned long get_msr(void)
	{
	unsigned long msr;

	asm volatile("mfmsr %0" : "=r" (msr) :);
	return msr;
	}

	static __inline__ void set_msr(unsigned long msr)
	{
	asm volatile("mtmsr %0" : : "r" (msr));
	}

	/*
	* Definitions to access the CPM Timer registers
	* See 8xx_immap.h for Internal Memory Map layout,
	* and commproc.h for CPM Interrupt vectors (aka "IRQ"s)
	*/

	typedef struct tid_8xx_cpmtimer_s {
	int cpm_vec; /* CPM Interrupt Vector for this timer */
	ushort tgcrp; / Pointer to Timer Global Config Reg. */
	ushort tmrp; / Pointer to Timer Mode Register */
	ushort trrp; / Pointer to Timer Reference Register */
	ushort tcrp; / Pointer to Timer Capture Register */
	ushort tcnp; / Pointer to Timer Counter Register */
	ushort terp; / Pointer to Timer Event Register */
	} tid_8xx_cpmtimer_t;

	#ifndef CLOCKRATE
	# define CLOCKRATE 64
	#endif

	#define CPMT_CLOCK_DIV 16
	#define CPMT_MAX_PRESCALER 256
	#define CPMT_MAX_REFERENCE 65535 /* max. unsigned short */

	#define CPMT_MAX_TICKS (CPMT_MAX_REFERENCE * CPMT_MAX_PRESCALER)
	#define CPMT_MAX_TICKS_WITH_DIV (CPMT_MAX_REFERENCE * CPMT_MAX_PRESCALER * CPMT_CLOCK_DIV)
	#define CPMT_MAX_INTERVAL (CPMT_MAX_TICKS_WITH_DIV / CLOCKRATE)

	/* For now: always use max. prescaler value */
	#define CPMT_PRESCALER (CPMT_MAX_PRESCALER)

	/* CPM Timer Event Register Bits */
	#define CPMT_EVENT_CAP 0x0001 /* Capture Event */
	#define CPMT_EVENT_REF 0x0002 /* Reference Counter Event */

	/* CPM Timer Global Config Register */
	#define CPMT_GCR_RST 0x0001 /* Reset Timer */
	#define CPMT_GCR_STP 0x0002 /* Stop Timer */
	#define CPMT_GCR_FRZ 0x0004 /* Freeze Timer */
	#define CPMT_GCR_GM_CAS 0x0008 /* Gate Mode / Cascade Timers */
	#define CPMT_GCR_MASK (CPMT_GCR_RST\|CPMT_GCR_STP\|CPMT_GCR_FRZ\|CPMT_GCR_GM_CAS)

	/* CPM Timer Mode register */
	#define CPMT_MR_GE 0x0001 /* Gate Enable */
	#define CPMT_MR_ICLK_CASC 0x0000 /* Clock internally cascaded */
	#define CPMT_MR_ICLK_CLK 0x0002 /* Clock = system clock */
	#define CPMT_MR_ICLK_CLKDIV 0x0004 /* Clock = system clock / 16 */
	#define CPMT_MR_ICLK_TIN 0x0006 /* Clock = TINx signal */
	#define CPMT_MR_FRR 0x0008 /* Free Run / Restart */
	#define CPMT_MR_ORI 0x0010 /* Out. Reference Interrupt En. */
	#define CPMT_MR_OM 0x0020 /* Output Mode */
	#define CPMT_MR_CE_DIS 0x0000 /* Capture/Interrupt disabled */
	#define CPMT_MR_CE_RISE 0x0040 /* Capt./Interr. on rising TIN */
	#define CPMT_MR_CE_FALL 0x0080 /* Capt./Interr. on falling TIN */
	#define CPMT_MR_CE_ANY 0x00C0 /* Capt./Interr. on any TIN edge*/


	/*
	* which CPM timer to use - index starts at 0 (= timer 1)
	*/
	#define TID_TIMER_ID 0 /* use CPM timer 1 */

	void setPeriod (tid_8xx_cpmtimer_t *hwp, ulong interval);

	static const char usage[] = "\n[q, b, e, ?] ";

	int timer (int argc, char * const argv[])
	{
	cpmtimer8xx_t cpmtimerp; / Pointer to the CPM Timer structure */
	tid_8xx_cpmtimer_t hw;
	tid_8xx_cpmtimer_t *hwp = &hw;
	int c;
	int running;

	app_startup(argv);

	/* Pointer to CPM Timer structure */
	cpmtimerp = &((immap_t *) gd->bd->bi_immr_base)->im_cpmtimer;

	printf ("TIMERS=0x%x\n", (unsigned) cpmtimerp);

	/* Initialize pointers depending on which timer we use */
	switch (TID_TIMER_ID) {
	case 0:
	hwp->tmrp = &(cpmtimerp->cpmt_tmr1);
	hwp->trrp = &(cpmtimerp->cpmt_trr1);
	hwp->tcrp = &(cpmtimerp->cpmt_tcr1);
	hwp->tcnp = &(cpmtimerp->cpmt_tcn1);
	hwp->terp = &(cpmtimerp->cpmt_ter1);
	hwp->cpm_vec = CPMVEC_TIMER1;
	break;
	case 1:
	hwp->tmrp = &(cpmtimerp->cpmt_tmr2);
	hwp->trrp = &(cpmtimerp->cpmt_trr2);
	hwp->tcrp = &(cpmtimerp->cpmt_tcr2);
	hwp->tcnp = &(cpmtimerp->cpmt_tcn2);
	hwp->terp = &(cpmtimerp->cpmt_ter2);
	hwp->cpm_vec = CPMVEC_TIMER2;
	break;
	case 2:
	hwp->tmrp = &(cpmtimerp->cpmt_tmr3);
	hwp->trrp = &(cpmtimerp->cpmt_trr3);
	hwp->tcrp = &(cpmtimerp->cpmt_tcr3);
	hwp->tcnp = &(cpmtimerp->cpmt_tcn3);
	hwp->terp = &(cpmtimerp->cpmt_ter3);
	hwp->cpm_vec = CPMVEC_TIMER3;
	break;
	case 3:
	hwp->tmrp = &(cpmtimerp->cpmt_tmr4);
	hwp->trrp = &(cpmtimerp->cpmt_trr4);
	hwp->tcrp = &(cpmtimerp->cpmt_tcr4);
	hwp->tcnp = &(cpmtimerp->cpmt_tcn4);
	hwp->terp = &(cpmtimerp->cpmt_ter4);
	hwp->cpm_vec = CPMVEC_TIMER4;
	break;
	}

	hwp->tgcrp = &cpmtimerp->cpmt_tgcr;

	printf ("Using timer %d\n"
	"tgcr @ 0x%x, tmr @ 0x%x, trr @ 0x%x,"
	" tcr @ 0x%x, tcn @ 0x%x, ter @ 0x%x\n",
	TID_TIMER_ID + 1,
	(unsigned) hwp->tgcrp,
	(unsigned) hwp->tmrp,
	(unsigned) hwp->trrp,
	(unsigned) hwp->tcrp,
	(unsigned) hwp->tcnp,
	(unsigned) hwp->terp
	);

	/* reset timer */
	*hwp->tgcrp &= ~(CPMT_GCR_MASK << TID_TIMER_ID);

	/* clear all events */
	*hwp->terp = (CPMT_EVENT_CAP \| CPMT_EVENT_REF);

	puts(usage);
	running = 0;
	while ((c = getc()) != 'q') {
	if (c == 'b') {

	setPeriod (hwp, TIMER_PERIOD); /* Set period and start ticking */

	/* Install interrupt handler (enable timer in CIMR) */
	install_hdlr (hwp->cpm_vec, timer_handler, hwp);

	printf ("Enabling timer\n");

	/* enable timer */
	*hwp->tgcrp \|= (CPMT_GCR_RST << TID_TIMER_ID);
	running = 1;

	#ifdef DEBUG
	printf ("tgcr=0x%x, tmr=0x%x, trr=0x%x,"
	" tcr=0x%x, tcn=0x%x, ter=0x%x\n",
	hwp->tgcrp, hwp->tmrp, *hwp->trrp,
	hwp->tcrp, hwp->tcnp, *hwp->terp
	);
	#endif
	} else if (c == 'e') {

	printf ("Stopping timer\n");

	*hwp->tgcrp &= ~(CPMT_GCR_MASK << TID_TIMER_ID);
	running = 0;

	#ifdef DEBUG
	printf ("tgcr=0x%x, tmr=0x%x, trr=0x%x,"
	" tcr=0x%x, tcn=0x%x, ter=0x%x\n",
	hwp->tgcrp, hwp->tmrp, *hwp->trrp,
	hwp->tcrp, hwp->tcnp, *hwp->terp
	);
	#endif
	/* Uninstall interrupt handler */
	free_hdlr (hwp->cpm_vec);

	} else if (c == '?') {
	#ifdef DEBUG
	cpic8xx_t cpm_icp = &((immap_t ) gd->bd->bi_immr_base)->im_cpic;
	sysconf8xx_t siup = &((immap_t ) gd->bd->bi_immr_base)->im_siu_conf;
	#endif

	printf ("\ntgcr=0x%x, tmr=0x%x, trr=0x%x,"
	" tcr=0x%x, tcn=0x%x, ter=0x%x\n",
	hwp->tgcrp, hwp->tmrp, *hwp->trrp,
	hwp->tcrp, hwp->tcnp, *hwp->terp
	);
	#ifdef DEBUG
	printf ("SIUMCR=0x%08lx, SYPCR=0x%08lx,"
	" SIMASK=0x%08lx, SIPEND=0x%08lx\n",
	siup->sc_siumcr,
	siup->sc_sypcr,
	siup->sc_simask,
	siup->sc_sipend
	);

	printf ("CIMR=0x%08lx, CICR=0x%08lx, CIPR=0x%08lx\n",
	cpm_icp->cpic_cimr,
	cpm_icp->cpic_cicr,
	cpm_icp->cpic_cipr
	);
	#endif
	} else {
	printf ("\nEnter: q - quit, b - start timer, e - stop timer, ? - get status\n");
	}
	puts(usage);
	}
	if (running) {
	printf ("Stopping timer\n");
	*hwp->tgcrp &= ~(CPMT_GCR_MASK << TID_TIMER_ID);
	free_hdlr (hwp->cpm_vec);
	}

	return (0);
	}


	/* Set period in microseconds and start.
	* Truncate to maximum period if more than this is requested - but warn about it.
	*/

	void setPeriod (tid_8xx_cpmtimer_t *hwp, ulong interval)
	{
	unsigned short prescaler;
	unsigned long ticks;

	printf ("Set interval %ld us\n", interval);

	/* Warn if requesting longer period than possible */
	if (interval > CPMT_MAX_INTERVAL) {
	printf ("Truncate interval %ld to maximum (%d)\n",
	interval, CPMT_MAX_INTERVAL);
	interval = CPMT_MAX_INTERVAL;
	}
	/*
	* Check if we want to use clock divider:
	* Since the reference counter can be incremented only in integer steps,
	* we try to keep it as big as possible to allow the resulting period to be
	* as precise as possible.
	*/
	/* prescaler, enable interrupt, restart after ref count is reached */
	prescaler = (ushort) ((CPMT_PRESCALER - 1) << 8) \|
	CPMT_MR_ORI \|
	CPMT_MR_FRR;

	ticks = ((ulong) CLOCKRATE * interval);

	if (ticks > CPMT_MAX_TICKS) {
	ticks /= CPMT_CLOCK_DIV;
	prescaler \|= CPMT_MR_ICLK_CLKDIV; /* use system clock divided by 16 */
	} else {
	prescaler \|= CPMT_MR_ICLK_CLK; /* use system clock without divider */
	}

	#ifdef DEBUG
	printf ("clock/%d, prescale factor %d, reference %ld, ticks %ld\n",
	(ticks > CPMT_MAX_TICKS) ? CPMT_CLOCK_DIV : 1,
	CPMT_PRESCALER,
	(ticks / CPMT_PRESCALER),
	ticks
	);
	#endif

	/* set prescaler register */
	*hwp->tmrp = prescaler;

	/* clear timer counter */
	*hwp->tcnp = 0;

	/* set reference register */
	*hwp->trrp = (unsigned short) (ticks / CPMT_PRESCALER);

	#ifdef DEBUG
	printf ("tgcr=0x%x, tmr=0x%x, trr=0x%x,"
	" tcr=0x%x, tcn=0x%x, ter=0x%x\n",
	hwp->tgcrp, hwp->tmrp, *hwp->trrp,
	hwp->tcrp, hwp->tcnp, *hwp->terp
	);
	#endif
	}

	/*
	* Handler for CPMVEC_TIMER1 interrupt
	*/
	static
	void timer_handler (void *arg)
	{
	tid_8xx_cpmtimer_t hwp = (tid_8xx_cpmtimer_t )arg;

	/* printf (" TER1=%04x ", hwp->terp); /

	/* just for demonstration */
	printf (".");

	/* clear all possible events: Ref. and Cap. */
	*hwp->terp = (CPMT_EVENT_CAP \| CPMT_EVENT_REF);
	}