[U-Boot-Users] Query regarding PSDMR register values.

[U-Boot-Users] Query regarding PSDMR register values.

[Apoorv_Sangal]

Hello All,
I am customizing Uboot for PowerQuiccII 8266 based PMC card.
Can anyone please let me know how the value of the PSDMR register is
obtained / calculated?
We are using MT48LC16M16A2 SDRAM (SODIMM). Specifically, we are looking or
the values of RFRC, PRETOACT, ACTTORW, LDOTOPRE and WRC fields in PSDMR. The
datasheet of SDRAM gives those values in nanoseconds.
But the PSDMR register in Uboot needs values in clock cycles.
Can anyone please tell me how to calculate the values for the required
fields (in clock cycles) from the values in the datasheet (in nanosecs)?

Thanks & Regards,
Apoorv Sangal.

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[U-Boot-Users] Query regarding PSDMR register values.

[Jerry Van Baren]

Apoorv_Sangal wrote:
> Hello All,
> I am customizing Uboot for PowerQuiccII 8266 based PMC card.
> Can anyone please let me know how the value of the PSDMR register is
> obtained / calculated?
> We are using MT48LC16M16A2 SDRAM (SODIMM). Specifically, we are looking or
> the values of RFRC, PRETOACT, ACTTORW, LDOTOPRE and WRC fields in PSDMR. The
> datasheet of SDRAM gives those values in nanoseconds.
> But the PSDMR register in Uboot needs values in clock cycles.
> Can anyone please tell me how to calculate the values for the required
> fields (in clock cycles) from the values in the datasheet (in nanosecs)?
> 
> Thanks & Regards,
> Apoorv Sangal.

freq = 1/time
time = 1/freq
clock cycles = time * freq

Pick the one that matches the problem and use consistent units.

Read the 8266 User's Manual and your board documentation/schematic to 
determine the frequency that your CPU is clocked at.  Use the "ceiling" 
function on your clock cycles calculation (i.e. "round up").

gvb