cpu/mpc8xx/speed.c - u-boot - Git at Google

 /*
  * (C) Copyright 2000-2004
  * Wolfgang Denk, DENX Software Engineering, wd@denx.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 <mpc8xx.h>
 #include <asm/processor.h>

 #if !defined(CONFIG_TQM866M) || defined(CFG_MEASURE_CPUCLK)

 #define PITC_SHIFT 16
 #define PITR_SHIFT 16
 /* pitc values to time for 58/8192 seconds (about 70.8 milliseconds) */
 #define SPEED_PIT_COUNTS 58
 #define SPEED_PITC	 ((SPEED_PIT_COUNTS - 1) << PITC_SHIFT)
 #define SPEED_PITC_INIT	 ((SPEED_PIT_COUNTS + 1) << PITC_SHIFT)

 /* 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));
 }

 /* ------------------------------------------------------------------------- */

 /*
  * Measure CPU clock speed (core clock GCLK1, GCLK2),
  * also determine bus clock speed (checking bus divider factor)
  *
  * (Approx. GCLK frequency in Hz)
  *
  * Initializes timer 2 and PIT, but disables them before return.
  * [Use timer 2, because MPC823 CPUs mask 0.x do not have timers 3 and 4]
  *
  * When measuring the CPU clock against the PIT, we count cpu clocks
  * for 58/8192 seconds with a prescale divide by 177 for the cpu clock.
  * These strange values for the timing interval and prescaling are used
  * because the formula for the CPU clock is:
  *
  *    CPU clock = count * (177 * (8192 / 58))
  *
  *		= count * 24999.7241
  *
  *    which is very close to
  *
  *		= count * 25000
  *
  * Since the count gives the CPU clock divided by 25000, we can get
  * the CPU clock rounded to the nearest 0.1 MHz by
  *
  *    CPU clock = ((count + 2) / 4) * 100000;
  *
  * The rounding is important since the measurement is sometimes going
  * to be high or low by 0.025 MHz, depending on exactly how the clocks
  * and counters interact. By rounding we get the exact answer for any
  * CPU clock that is an even multiple of 0.1 MHz.
  */

 unsigned long measure_gclk(void)
 {
 	volatile immap_t *immr = (immap_t *) CFG_IMMR;
 	volatile cpmtimer8xx_t *timerp = &immr->im_cpmtimer;
 	ulong timer2_val;
 	ulong msr_val;

 #ifdef CFG_8XX_XIN
 	/* dont use OSCM, only use EXTCLK/512 */
 	immr->im_clkrst.car_sccr |= SCCR_RTSEL | SCCR_RTDIV;
 #else
 	immr->im_clkrst.car_sccr &= ~(SCCR_RTSEL | SCCR_RTDIV);
 #endif

 	/* Reset + Stop Timer 2, no cascading
 	 */
 	timerp->cpmt_tgcr &= ~(TGCR_CAS2 | TGCR_RST2);

 	/* Keep stopped, halt in debug mode
 	 */
 	timerp->cpmt_tgcr |= (TGCR_FRZ2 | TGCR_STP2);

 	/* Timer 2 setup:
 	 * Output ref. interrupt disable, int. clock
 	 * Prescale by 177. Note that prescaler divides by value + 1
 	 * so we must subtract 1 here.
 	 */
 	timerp->cpmt_tmr2 = ((177 - 1) << TMR_PS_SHIFT) | TMR_ICLK_IN_GEN;

 	timerp->cpmt_tcn2 = 0;		/* reset state		*/
 	timerp->cpmt_tgcr |= TGCR_RST2;	/* enable timer 2	*/

 	/*
 	 * PIT setup:
 	 *
 	 * We want to time for SPEED_PITC_COUNTS counts (of 8192 Hz),
 	 * so the count value would be SPEED_PITC_COUNTS - 1.
 	 * But there would be an uncertainty in the start time of 1/4
 	 * count since when we enable the PIT the count is not
 	 * synchronized to the 32768 Hz oscillator. The trick here is
 	 * to start the count higher and wait until the PIT count
 	 * changes to the required value before starting timer 2.
 	 *
 	 * One count high should be enough, but occasionally the start
 	 * is off by 1 or 2 counts of 32768 Hz. With the start value
 	 * set two counts high it seems very reliable.
 	 */

 	immr->im_sitk.sitk_pitck = KAPWR_KEY;	/* PIT initialization */
 	immr->im_sit.sit_pitc = SPEED_PITC_INIT;

 	immr->im_sitk.sitk_piscrk = KAPWR_KEY;
 	immr->im_sit.sit_piscr = CFG_PISCR;

 	/*
 	 * Start measurement - disable interrupts, just in case
 	 */
 	msr_val = get_msr ();
 	set_msr (msr_val & ~MSR_EE);

 	immr->im_sit.sit_piscr |= PISCR_PTE;

 	/* spin until get exact count when we want to start */
 	while (immr->im_sit.sit_pitr > SPEED_PITC);

 	timerp->cpmt_tgcr &= ~TGCR_STP2;	/* Start Timer 2	*/
 	while ((immr->im_sit.sit_piscr & PISCR_PS) == 0);
 	timerp->cpmt_tgcr |= TGCR_STP2;		/* Stop  Timer 2	*/

 	/* re-enable external interrupts if they were on */
 	set_msr (msr_val);

 	/* Disable timer and PIT
 	 */
 	timer2_val = timerp->cpmt_tcn2;		/* save before reset timer */

 	timerp->cpmt_tgcr &= ~(TGCR_RST2 | TGCR_FRZ2 | TGCR_STP2);
 	immr->im_sit.sit_piscr &= ~PISCR_PTE;

 #if defined(CFG_8XX_XIN)
 	/* not using OSCM, using XIN, so scale appropriately */
 	return (((timer2_val + 2) / 4) * (CFG_8XX_XIN/512))/8192 * 100000L;
 #else
 	return ((timer2_val + 2) / 4) * 100000L;	/* convert to Hz	*/
 #endif
 }

 #endif

 #if !defined(CONFIG_TQM866M)

 /*
  * get_clocks() fills in gd->cpu_clock depending on CONFIG_8xx_GCLK_FREQ
  * or (if it is not defined) measure_gclk() (which uses the ref clock)
  * from above.
  */
 int get_clocks (void)
 {
 	DECLARE_GLOBAL_DATA_PTR;

 	uint immr = get_immr (0);	/* Return full IMMR contents */
 	volatile immap_t *immap = (immap_t *) (immr & 0xFFFF0000);
 	uint sccr = immap->im_clkrst.car_sccr;
 	/*
 	 * If for some reason measuring the gclk frequency won't
 	 * work, we return the hardwired value.
 	 * (For example, the cogent CMA286-60 CPU module has no
 	 * separate oscillator for PITRTCLK)
 	 */
 #if defined(CONFIG_8xx_GCLK_FREQ)
 	gd->cpu_clk = CONFIG_8xx_GCLK_FREQ;
 #elif defined(CONFIG_8xx_OSCLK)
 #define PLPRCR_val(a) ((pll & PLPRCR_ ## a ## _MSK) >> PLPRCR_ ## a ## _SHIFT)
 	uint pll = immap->im_clkrst.car_plprcr;
 	uint clk;

 	if ((immr & 0x0FFF) >= MPC8xx_NEW_CLK) { /* MPC866/87x/88x series */
 		clk = ((CONFIG_8xx_OSCLK / (PLPRCR_val(PDF)+1)) *
 		       (PLPRCR_val(MFI) + PLPRCR_val(MFN) / (PLPRCR_val(MFD)+1))) /
 			(1<<PLPRCR_val(S));
 	} else {
 		clk = CONFIG_8xx_OSCLK * (PLPRCR_val(MF)+1);
 	}
 	if (pll & PLPRCR_CSRC) {	/* Low frequency division factor is used  */
 		gd->cpu_clk = clk / (2 << ((sccr >> 8) & 7));
 	} else {			/* High frequency division factor is used */
 		gd->cpu_clk = clk / (1 << ((sccr >> 5) & 7));
 	}
 #else
 	gd->cpu_clk = measure_gclk();
 #endif /* CONFIG_8xx_GCLK_FREQ */

 	if ((sccr & SCCR_EBDF11) == 0) {
 		/* No Bus Divider active */
 		gd->bus_clk = gd->cpu_clk;
 	} else {
 		/* The MPC8xx has only one BDF: half clock speed */
 		gd->bus_clk = gd->cpu_clk / 2;
 	}

 	return (0);
 }

 #else /* CONFIG_MPC866_FAMILY */

 static long init_pll_866 (long clk);

 /* This function sets up PLL (init_pll_866() is called) and
  * fills gd->cpu_clk and gd->bus_clk according to the environment
  * variable 'cpuclk' or to CFG_866_CPUCLK_DEFAULT (if 'cpuclk'
  * contains invalid value).
  * This functions requires an MPC866 series CPU.
  */
 int get_clocks_866 (void)
 {
 	DECLARE_GLOBAL_DATA_PTR;

 	volatile immap_t *immr = (immap_t *) CFG_IMMR;
 	char		  tmp[64];
 	long		  cpuclk = 0;
 	long		  sccr_reg;

 	if (getenv_r ("cpuclk", tmp, sizeof (tmp)) > 0)
 		cpuclk = simple_strtoul (tmp, NULL, 10) * 1000000;

 	if ((CFG_866_CPUCLK_MIN > cpuclk) || (CFG_866_CPUCLK_MAX < cpuclk))
 		cpuclk = CFG_866_CPUCLK_DEFAULT;

 	gd->cpu_clk = init_pll_866 (cpuclk);
 #if defined(CFG_MEASURE_CPUCLK)
 	gd->cpu_clk = measure_gclk ();
 #endif

 	/* if cpu clock <= 66 MHz then set bus division factor to 1,
 	 * otherwise set it to 2
 	 */
 	sccr_reg = immr->im_clkrst.car_sccr;
 	sccr_reg &= ~SCCR_EBDF11;
 	if (gd->cpu_clk <= 66000000) {
 		sccr_reg |= SCCR_EBDF00;	/* bus division factor = 1 */
 		gd->bus_clk = gd->cpu_clk;
 	} else {
 		sccr_reg |= SCCR_EBDF01;	/* bus division factor = 2 */
 		gd->bus_clk = gd->cpu_clk / 2;
 	}
 	immr->im_clkrst.car_sccr = sccr_reg;

 	return (0);
 }

 /* Adjust sdram refresh rate to actual CPU clock.
  */
 int sdram_adjust_866 (void)
 {
 	DECLARE_GLOBAL_DATA_PTR;

 	volatile immap_t *immr = (immap_t *) CFG_IMMR;
 	long		  mamr;

 	mamr = immr->im_memctl.memc_mamr;
 	mamr &= ~MAMR_PTA_MSK;
 	mamr |= ((gd->cpu_clk / CFG_866_PTA_PER_CLK) << MAMR_PTA_SHIFT);
 	immr->im_memctl.memc_mamr = mamr;

 	return (0);
 }

 /* Configure PLL for MPC866/859 CPU series
  * PLL multiplication factor is set to the value nearest to the desired clk,
  * assuming a oscclk of 10 MHz.
  */
 static long init_pll_866 (long clk)
 {
 	extern void plprcr_write_866 (long);

 	volatile immap_t *immr = (immap_t *) CFG_IMMR;
 	long		  n, plprcr;
 	char		  mfi, mfn, mfd, s, pdf;
 	long		  step_mfi, step_mfn;

 	if (clk < 20000000) {
 		clk *= 2;
 		pdf = 1;
 	} else {
 		pdf = 0;
 	}

 	if (clk < 40000000) {
 		s = 2;
 		step_mfi = CFG_866_OSCCLK / 4;
 		mfd = 7;
 		step_mfn = CFG_866_OSCCLK / 30;
 	} else if (clk < 80000000) {
 		s = 1;
 		step_mfi = CFG_866_OSCCLK / 2;
 		mfd = 14;
 		step_mfn = CFG_866_OSCCLK / 30;
 	} else {
 		s = 0;
 		step_mfi = CFG_866_OSCCLK;
 		mfd = 29;
 		step_mfn = CFG_866_OSCCLK / 30;
 	}

 	/* Calculate integer part of multiplication factor
 	 */
 	n = clk / step_mfi;
 	mfi = (char)n;

 	/* Calculate numerator of fractional part of multiplication factor
 	 */
 	n = clk - (n * step_mfi);
 	mfn = (char)(n / step_mfn);

 	/* Calculate effective clk
 	 */
 	n = ((mfi * step_mfi) + (mfn * step_mfn)) / (pdf + 1);

 	immr->im_clkrstk.cark_plprcrk = KAPWR_KEY;

 	plprcr = (immr->im_clkrst.car_plprcr & ~(PLPRCR_MFN_MSK
 			| PLPRCR_MFD_MSK | PLPRCR_S_MSK
 			| PLPRCR_MFI_MSK | PLPRCR_DBRMO
 			| PLPRCR_PDF_MSK))
 			| (mfn << PLPRCR_MFN_SHIFT)
 			| (mfd << PLPRCR_MFD_SHIFT)
 			| (s << PLPRCR_S_SHIFT)
 			| (mfi << PLPRCR_MFI_SHIFT)
 			| (pdf << PLPRCR_PDF_SHIFT);

 	if( (mfn > 0) && ((mfd / mfn) > 10) )
 		plprcr |= PLPRCR_DBRMO;

 	plprcr_write_866 (plprcr);		/* set value using SIU4/9 workaround */
 	immr->im_clkrstk.cark_plprcrk = 0x00000000;

 	return (n);
 }

 #endif /* CONFIG_MPC866_FAMILY */

 #if defined(CONFIG_TQM8xxL) && !defined(CONFIG_TQM866M)
 /*
  * Adjust sdram refresh rate to actual CPU clock
  * and set timebase source according to actual CPU clock
  */
 int adjust_sdram_tbs_8xx (void)
 {
 	DECLARE_GLOBAL_DATA_PTR;

 	volatile immap_t *immr = (immap_t *) CFG_IMMR;
 	long		  mamr;
 	long              sccr;

 	mamr = immr->im_memctl.memc_mamr;
 	mamr &= ~MAMR_PTA_MSK;
 	mamr |= ((gd->cpu_clk / CFG_PTA_PER_CLK) << MAMR_PTA_SHIFT);
 	immr->im_memctl.memc_mamr = mamr;

 	if (gd->cpu_clk < 67000000) {
 		sccr = immr->im_clkrst.car_sccr;
 		sccr |= SCCR_TBS;
 		immr->im_clkrst.car_sccr = sccr;
 	}

 	return (0);
 }
 #endif /* CONFIG_TQM8xxL/M, !TQM866M */

 /* ------------------------------------------------------------------------- */
	/*
	* (C) Copyright 2000-2004
	* Wolfgang Denk, DENX Software Engineering, wd@denx.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 <mpc8xx.h>
	#include <asm/processor.h>

	#if !defined(CONFIG_TQM866M) \|\| defined(CFG_MEASURE_CPUCLK)

	#define PITC_SHIFT 16
	#define PITR_SHIFT 16
	/* pitc values to time for 58/8192 seconds (about 70.8 milliseconds) */
	#define SPEED_PIT_COUNTS 58
	#define SPEED_PITC ((SPEED_PIT_COUNTS - 1) << PITC_SHIFT)
	#define SPEED_PITC_INIT ((SPEED_PIT_COUNTS + 1) << PITC_SHIFT)

	/* 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));
	}

	/* ------------------------------------------------------------------------- */

	/*
	* Measure CPU clock speed (core clock GCLK1, GCLK2),
	* also determine bus clock speed (checking bus divider factor)
	*
	* (Approx. GCLK frequency in Hz)
	*
	* Initializes timer 2 and PIT, but disables them before return.
	* [Use timer 2, because MPC823 CPUs mask 0.x do not have timers 3 and 4]
	*
	* When measuring the CPU clock against the PIT, we count cpu clocks
	* for 58/8192 seconds with a prescale divide by 177 for the cpu clock.
	* These strange values for the timing interval and prescaling are used
	* because the formula for the CPU clock is:
	*
	* CPU clock = count * (177 * (8192 / 58))
	*
	* = count * 24999.7241
	*
	* which is very close to
	*
	* = count * 25000
	*
	* Since the count gives the CPU clock divided by 25000, we can get
	* the CPU clock rounded to the nearest 0.1 MHz by
	*
	* CPU clock = ((count + 2) / 4) * 100000;
	*
	* The rounding is important since the measurement is sometimes going
	* to be high or low by 0.025 MHz, depending on exactly how the clocks
	* and counters interact. By rounding we get the exact answer for any
	* CPU clock that is an even multiple of 0.1 MHz.
	*/

	unsigned long measure_gclk(void)
	{
	volatile immap_t immr = (immap_t ) CFG_IMMR;
	volatile cpmtimer8xx_t *timerp = &immr->im_cpmtimer;
	ulong timer2_val;
	ulong msr_val;

	#ifdef CFG_8XX_XIN
	/* dont use OSCM, only use EXTCLK/512 */
	immr->im_clkrst.car_sccr \|= SCCR_RTSEL \| SCCR_RTDIV;
	#else
	immr->im_clkrst.car_sccr &= ~(SCCR_RTSEL \| SCCR_RTDIV);
	#endif

	/* Reset + Stop Timer 2, no cascading
	*/
	timerp->cpmt_tgcr &= ~(TGCR_CAS2 \| TGCR_RST2);

	/* Keep stopped, halt in debug mode
	*/
	timerp->cpmt_tgcr \|= (TGCR_FRZ2 \| TGCR_STP2);

	/* Timer 2 setup:
	* Output ref. interrupt disable, int. clock
	* Prescale by 177. Note that prescaler divides by value + 1
	* so we must subtract 1 here.
	*/
	timerp->cpmt_tmr2 = ((177 - 1) << TMR_PS_SHIFT) \| TMR_ICLK_IN_GEN;

	timerp->cpmt_tcn2 = 0; /* reset state */
	timerp->cpmt_tgcr \|= TGCR_RST2; /* enable timer 2 */

	/*
	* PIT setup:
	*
	* We want to time for SPEED_PITC_COUNTS counts (of 8192 Hz),
	* so the count value would be SPEED_PITC_COUNTS - 1.
	* But there would be an uncertainty in the start time of 1/4
	* count since when we enable the PIT the count is not
	* synchronized to the 32768 Hz oscillator. The trick here is
	* to start the count higher and wait until the PIT count
	* changes to the required value before starting timer 2.
	*
	* One count high should be enough, but occasionally the start
	* is off by 1 or 2 counts of 32768 Hz. With the start value
	* set two counts high it seems very reliable.
	*/

	immr->im_sitk.sitk_pitck = KAPWR_KEY; /* PIT initialization */
	immr->im_sit.sit_pitc = SPEED_PITC_INIT;

	immr->im_sitk.sitk_piscrk = KAPWR_KEY;
	immr->im_sit.sit_piscr = CFG_PISCR;

	/*
	* Start measurement - disable interrupts, just in case
	*/
	msr_val = get_msr ();
	set_msr (msr_val & ~MSR_EE);

	immr->im_sit.sit_piscr \|= PISCR_PTE;

	/* spin until get exact count when we want to start */
	while (immr->im_sit.sit_pitr > SPEED_PITC);

	timerp->cpmt_tgcr &= ~TGCR_STP2; /* Start Timer 2 */
	while ((immr->im_sit.sit_piscr & PISCR_PS) == 0);
	timerp->cpmt_tgcr \|= TGCR_STP2; /* Stop Timer 2 */

	/* re-enable external interrupts if they were on */
	set_msr (msr_val);

	/* Disable timer and PIT
	*/
	timer2_val = timerp->cpmt_tcn2; /* save before reset timer */

	timerp->cpmt_tgcr &= ~(TGCR_RST2 \| TGCR_FRZ2 \| TGCR_STP2);
	immr->im_sit.sit_piscr &= ~PISCR_PTE;

	#if defined(CFG_8XX_XIN)
	/* not using OSCM, using XIN, so scale appropriately */
	return (((timer2_val + 2) / 4) * (CFG_8XX_XIN/512))/8192 * 100000L;
	#else
	return ((timer2_val + 2) / 4) * 100000L; /* convert to Hz */
	#endif
	}

	#endif

	#if !defined(CONFIG_TQM866M)

	/*
	* get_clocks() fills in gd->cpu_clock depending on CONFIG_8xx_GCLK_FREQ
	* or (if it is not defined) measure_gclk() (which uses the ref clock)
	* from above.
	*/
	int get_clocks (void)
	{
	DECLARE_GLOBAL_DATA_PTR;

	uint immr = get_immr (0); /* Return full IMMR contents */
	volatile immap_t immap = (immap_t ) (immr & 0xFFFF0000);
	uint sccr = immap->im_clkrst.car_sccr;
	/*
	* If for some reason measuring the gclk frequency won't
	* work, we return the hardwired value.
	* (For example, the cogent CMA286-60 CPU module has no
	* separate oscillator for PITRTCLK)
	*/
	#if defined(CONFIG_8xx_GCLK_FREQ)
	gd->cpu_clk = CONFIG_8xx_GCLK_FREQ;
	#elif defined(CONFIG_8xx_OSCLK)
	#define PLPRCR_val(a) ((pll & PLPRCR_ ## a ## _MSK) >> PLPRCR_ ## a ## _SHIFT)
	uint pll = immap->im_clkrst.car_plprcr;
	uint clk;

	if ((immr & 0x0FFF) >= MPC8xx_NEW_CLK) { /* MPC866/87x/88x series */
	clk = ((CONFIG_8xx_OSCLK / (PLPRCR_val(PDF)+1)) *
	(PLPRCR_val(MFI) + PLPRCR_val(MFN) / (PLPRCR_val(MFD)+1))) /
	(1<<PLPRCR_val(S));
	} else {
	clk = CONFIG_8xx_OSCLK * (PLPRCR_val(MF)+1);
	}
	if (pll & PLPRCR_CSRC) { /* Low frequency division factor is used */
	gd->cpu_clk = clk / (2 << ((sccr >> 8) & 7));
	} else { /* High frequency division factor is used */
	gd->cpu_clk = clk / (1 << ((sccr >> 5) & 7));
	}
	#else
	gd->cpu_clk = measure_gclk();
	#endif /* CONFIG_8xx_GCLK_FREQ */

	if ((sccr & SCCR_EBDF11) == 0) {
	/* No Bus Divider active */
	gd->bus_clk = gd->cpu_clk;
	} else {
	/* The MPC8xx has only one BDF: half clock speed */
	gd->bus_clk = gd->cpu_clk / 2;
	}

	return (0);
	}

	#else /* CONFIG_MPC866_FAMILY */

	static long init_pll_866 (long clk);

	/* This function sets up PLL (init_pll_866() is called) and
	* fills gd->cpu_clk and gd->bus_clk according to the environment
	* variable 'cpuclk' or to CFG_866_CPUCLK_DEFAULT (if 'cpuclk'
	* contains invalid value).
	* This functions requires an MPC866 series CPU.
	*/
	int get_clocks_866 (void)
	{
	DECLARE_GLOBAL_DATA_PTR;

	volatile immap_t immr = (immap_t ) CFG_IMMR;
	char tmp[64];
	long cpuclk = 0;
	long sccr_reg;

	if (getenv_r ("cpuclk", tmp, sizeof (tmp)) > 0)
	cpuclk = simple_strtoul (tmp, NULL, 10) * 1000000;

	if ((CFG_866_CPUCLK_MIN > cpuclk) \|\| (CFG_866_CPUCLK_MAX < cpuclk))
	cpuclk = CFG_866_CPUCLK_DEFAULT;

	gd->cpu_clk = init_pll_866 (cpuclk);
	#if defined(CFG_MEASURE_CPUCLK)
	gd->cpu_clk = measure_gclk ();
	#endif

	/* if cpu clock <= 66 MHz then set bus division factor to 1,
	* otherwise set it to 2
	*/
	sccr_reg = immr->im_clkrst.car_sccr;
	sccr_reg &= ~SCCR_EBDF11;
	if (gd->cpu_clk <= 66000000) {
	sccr_reg \|= SCCR_EBDF00; /* bus division factor = 1 */
	gd->bus_clk = gd->cpu_clk;
	} else {
	sccr_reg \|= SCCR_EBDF01; /* bus division factor = 2 */
	gd->bus_clk = gd->cpu_clk / 2;
	}
	immr->im_clkrst.car_sccr = sccr_reg;

	return (0);
	}

	/* Adjust sdram refresh rate to actual CPU clock.
	*/
	int sdram_adjust_866 (void)
	{
	DECLARE_GLOBAL_DATA_PTR;

	volatile immap_t immr = (immap_t ) CFG_IMMR;
	long mamr;

	mamr = immr->im_memctl.memc_mamr;
	mamr &= ~MAMR_PTA_MSK;
	mamr \|= ((gd->cpu_clk / CFG_866_PTA_PER_CLK) << MAMR_PTA_SHIFT);
	immr->im_memctl.memc_mamr = mamr;

	return (0);
	}

	/* Configure PLL for MPC866/859 CPU series
	* PLL multiplication factor is set to the value nearest to the desired clk,
	* assuming a oscclk of 10 MHz.
	*/
	static long init_pll_866 (long clk)
	{
	extern void plprcr_write_866 (long);

	volatile immap_t immr = (immap_t ) CFG_IMMR;
	long n, plprcr;
	char mfi, mfn, mfd, s, pdf;
	long step_mfi, step_mfn;

	if (clk < 20000000) {
	clk *= 2;
	pdf = 1;
	} else {
	pdf = 0;
	}

	if (clk < 40000000) {
	s = 2;
	step_mfi = CFG_866_OSCCLK / 4;
	mfd = 7;
	step_mfn = CFG_866_OSCCLK / 30;
	} else if (clk < 80000000) {
	s = 1;
	step_mfi = CFG_866_OSCCLK / 2;
	mfd = 14;
	step_mfn = CFG_866_OSCCLK / 30;
	} else {
	s = 0;
	step_mfi = CFG_866_OSCCLK;
	mfd = 29;
	step_mfn = CFG_866_OSCCLK / 30;
	}

	/* Calculate integer part of multiplication factor
	*/
	n = clk / step_mfi;
	mfi = (char)n;

	/* Calculate numerator of fractional part of multiplication factor
	*/
	n = clk - (n * step_mfi);
	mfn = (char)(n / step_mfn);

	/* Calculate effective clk
	*/
	n = ((mfi * step_mfi) + (mfn * step_mfn)) / (pdf + 1);

	immr->im_clkrstk.cark_plprcrk = KAPWR_KEY;

	plprcr = (immr->im_clkrst.car_plprcr & ~(PLPRCR_MFN_MSK
	\| PLPRCR_MFD_MSK \| PLPRCR_S_MSK
	\| PLPRCR_MFI_MSK \| PLPRCR_DBRMO
	\| PLPRCR_PDF_MSK))
	\| (mfn << PLPRCR_MFN_SHIFT)
	\| (mfd << PLPRCR_MFD_SHIFT)
	\| (s << PLPRCR_S_SHIFT)
	\| (mfi << PLPRCR_MFI_SHIFT)
	\| (pdf << PLPRCR_PDF_SHIFT);

	if( (mfn > 0) && ((mfd / mfn) > 10) )
	plprcr \|= PLPRCR_DBRMO;

	plprcr_write_866 (plprcr); /* set value using SIU4/9 workaround */
	immr->im_clkrstk.cark_plprcrk = 0x00000000;

	return (n);
	}

	#endif /* CONFIG_MPC866_FAMILY */

	#if defined(CONFIG_TQM8xxL) && !defined(CONFIG_TQM866M)
	/*
	* Adjust sdram refresh rate to actual CPU clock
	* and set timebase source according to actual CPU clock
	*/
	int adjust_sdram_tbs_8xx (void)
	{
	DECLARE_GLOBAL_DATA_PTR;

	volatile immap_t immr = (immap_t ) CFG_IMMR;
	long mamr;
	long sccr;

	mamr = immr->im_memctl.memc_mamr;
	mamr &= ~MAMR_PTA_MSK;
	mamr \|= ((gd->cpu_clk / CFG_PTA_PER_CLK) << MAMR_PTA_SHIFT);
	immr->im_memctl.memc_mamr = mamr;

	if (gd->cpu_clk < 67000000) {
	sccr = immr->im_clkrst.car_sccr;
	sccr \|= SCCR_TBS;
	immr->im_clkrst.car_sccr = sccr;
	}

	return (0);
	}
	#endif /* CONFIG_TQM8xxL/M, !TQM866M */

	/* ------------------------------------------------------------------------- */