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authorwdenk <wdenk>2004-02-11 21:35:18 +0000
committerwdenk <wdenk>2004-02-11 21:35:18 +0000
commita2d18bb7d31e7b971386fef505ff0218f3b6e893 (patch)
tree3230d5f1333740d174aae9901acde345be1a333f /cpu/mpc8xx
parentcd37d9e6e5e9692d8efafc155df23fa142b63d03 (diff)
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* Make sure to use a bus clock divider of 2 only when running TQM8xxM
modules at CPU clock frequencies above 66 MHz. * Optimize flash programming speed for LWMON (by another 100% :-)
Diffstat (limited to 'cpu/mpc8xx')
-rw-r--r--cpu/mpc8xx/speed.c46
1 files changed, 28 insertions, 18 deletions
diff --git a/cpu/mpc8xx/speed.c b/cpu/mpc8xx/speed.c
index 8f8efce..aebfbcb 100644
--- a/cpu/mpc8xx/speed.c
+++ b/cpu/mpc8xx/speed.c
@@ -64,18 +64,18 @@ static __inline__ void set_msr(unsigned long msr)
* 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))
+ * CPU clock = count * (177 * (8192 / 58))
*
- * = count * 24999.7241
+ * = count * 24999.7241
*
- * which is very close to
+ * which is very close to
*
- * = count * 25000
+ * = 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;
+ * 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
@@ -112,8 +112,8 @@ unsigned long measure_gclk(void)
*/
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 */
+ timerp->cpmt_tcn2 = 0; /* reset state */
+ timerp->cpmt_tgcr |= TGCR_RST2; /* enable timer 2 */
/*
* PIT setup:
@@ -148,9 +148,9 @@ unsigned long measure_gclk(void)
/* 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 */
+ 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 */
+ timerp->cpmt_tgcr |= TGCR_STP2; /* Stop Timer 2 */
/* re-enable external interrupts if they were on */
set_msr (msr_val);
@@ -166,7 +166,7 @@ unsigned long measure_gclk(void)
/* 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 */
+ return ((timer2_val + 2) / 4) * 100000L; /* convert to Hz */
#endif
}
@@ -224,8 +224,9 @@ int get_clocks_866 (void)
DECLARE_GLOBAL_DATA_PTR;
volatile immap_t *immr = (immap_t *) CFG_IMMR;
- char tmp[64];
- long cpuclk = 0;
+ char tmp[64];
+ long cpuclk = 0;
+ long sccr_reg;
if (getenv_r ("cpuclk", tmp, sizeof (tmp)) > 0)
cpuclk = simple_strtoul (tmp, NULL, 10) * 1000000;
@@ -238,10 +239,19 @@ int get_clocks_866 (void)
gd->cpu_clk = measure_gclk ();
#endif
- if ((immr->im_clkrst.car_sccr & SCCR_EBDF11) == 0)
+ /* 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
+ } 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);
}
@@ -253,7 +263,7 @@ int sdram_adjust_866 (void)
DECLARE_GLOBAL_DATA_PTR;
volatile immap_t *immr = (immap_t *) CFG_IMMR;
- long mamr;
+ long mamr;
mamr = immr->im_memctl.memc_mamr;
mamr &= ~MAMR_PTA_MSK;
@@ -272,9 +282,9 @@ 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;
+ long n, plprcr;
+ char mfi, mfn, mfd, s, pdf;
+ long step_mfi, step_mfn;
if (clk < 20000000) {
clk *= 2;