This is kind of a bug report. The Kinetis 120MHz bare metal sample code revision 1.4 from December has different part with low quality. The code can be found here.
Among other things:
Mch.h contains a prototype for void rtc_as_refclk(void); event though this function is not implemented anywhere. E.g. you need to stub it, for compiling the code with a compiler where this is an issue.
From running a static code analyzer, the following comes up.
Output from Compiling mcg.c:
"..\..\..\ThirdParty\KINETIS_120MHZ_SC\KINETIS_120MHZ_SC\src\drivers\mcg\mcg.c", line 187: source analysis warning #15:
"temp_reg" set but never read
temp_reg &= ~(MCG_C1_CLKS_MASK | MCG_C1_FRDIV_MASK | MCG_C1_IREFS_MASK); // Clear values in these fields
^
"..\..\..\ThirdParty\KINETIS_120MHZ_SC\KINETIS_120MHZ_SC\src\drivers\mcg\mcg.c", line 2039:
(when called from
..\..\..\ThirdParty\KINETIS_120MHZ_SC\KINETIS_120MHZ_SC\src\drivers\m
cg\mcg.c line 876) source analysis error #14: read of potentially
uninitialized variable "fll_freq_hz"
return fll_freq_hz;
^
"..\..\..\ThirdParty\KINETIS_120MHZ_SC\KINETIS_120MHZ_SC\src\drivers\mcg\mcg.c", line 987: source analysis warning #15:
"temp_reg" set but never read
temp_reg &= ~(MCG_C1_CLKS_MASK | MCG_C1_FRDIV_MASK | MCG_C1_IREFS_MASK); // Clear values in these fields
^
"..\..\..\ThirdParty\KINETIS_120MHZ_SC\KINETIS_120MHZ_SC\src\drivers\mcg\mcg.c", line 1250: source analysis warning #15:
"temp_reg" set but never read
temp_reg &= ~(MCG_C1_CLKS_MASK | MCG_C1_FRDIV_MASK | MCG_C1_IREFS_MASK); // Clear values in these fields
^
"..\..\..\ThirdParty\KINETIS_120MHZ_SC\KINETIS_120MHZ_SC\src\drivers\mcg\mcg.c", line 1453: source analysis warning #15:
"temp_reg" set but never read
temp_reg &= ~(MCG_C1_CLKS_MASK | MCG_C1_FRDIV_MASK | MCG_C1_IREFS_MASK); // Clear CLKS, FRDIV and IREFS fields
^
"..\..\..\ThirdParty\KINETIS_120MHZ_SC\KINETIS_120MHZ_SC\src\drivers\mcg\mcg.c", line 1800: source analysis warning #15:
"temp_reg" set but never read
temp_reg &= ~(MCG_C1_CLKS_MASK | MCG_C1_FRDIV_MASK | MCG_C1_IREFS_MASK); // Clear values in these fields
^
Just FYI, in a hope that when you release version 1.5 is it fixed.
Have a nice day.