Fix variable CPU clock for MPC859/866 systems for low CPU clocks

[platform/kernel/u-boot.git] / cpu / mpc8xx / speed.c

diff --git a/cpu/mpc8xx/speed.c b/cpu/mpc8xx/speed.c
index 8583eef..8f8efce 100644 (file)
--- a/cpu/mpc8xx/speed.c
+++ b/cpu/mpc8xx/speed.c
@@ -25,7 +25,7 @@
 #include <mpc8xx.h>
 #include <asm/processor.h>
 
-#ifndef CONFIG_TQM866M
+#if !defined(CONFIG_TQM866M) || defined(CFG_MEASURE_CPUCLK)
 
 #define PITC_SHIFT 16
 #define PITR_SHIFT 16
@@ -170,6 +170,10 @@ unsigned long measure_gclk(void)
 #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)
@@ -230,6 +234,9 @@ int get_clocks_866 (void)
                cpuclk = CFG_866_CPUCLK_DEFAULT;
 
        gd->cpu_clk = init_pll_866 (cpuclk);
+#if defined(CFG_MEASURE_CPUCLK)
+       gd->cpu_clk = measure_gclk ();
+#endif
 
        if ((immr->im_clkrst.car_sccr & SCCR_EBDF11) == 0)
                gd->bus_clk = gd->cpu_clk;
@@ -269,8 +276,19 @@ static long init_pll_866 (long clk)
        char              mfi, mfn, mfd, s, pdf;
        long              step_mfi, step_mfn;
 
-       pdf = 0;
-       if (clk < 80000000) {
+       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;
@@ -294,13 +312,14 @@ static long init_pll_866 (long clk)
 
        /* Calculate effective clk
         */
-       n = (mfi * step_mfi) + (mfn * step_mfn);
+       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_MFI_MSK | PLPRCR_DBRMO
+                       | PLPRCR_PDF_MSK))
                        | (mfn << PLPRCR_MFN_SHIFT)
                        | (mfd << PLPRCR_MFD_SHIFT)
                        | (s << PLPRCR_S_SHIFT)