[U-Boot-Users] PPC CLKIN
We currently have several PQII and PQIII PrPMC boards that dynamically support PCI bus speeds between 25 MHz and 133 MHz. These boards provide a CPLD register that gives PCI frequency. I would like to take advantage of this register, if possible, within u-boot rather than using a #define such as CONFIG_83XX_CLKIN, CONFIG_8260_CLKIN, or CONFIG_SYS_CLK_FREQ for the input clock frequency to the processor. Is there a suggested method of doing this?
For testing I have implemented the following in get_sys_info() in speed.c for an MPC8560 board:
#if !defined (CONFIG_SYS_CLK_FREQ) sysInfo->freqSystemBus = plat_ratio * get_sys_clk(); #else sysInfo->freqSystemBus = plat_ratio * CONFIG_SYS_CLK_FREQ; #endif
The get_sys_clk() function resides in the board code directory. Would this be an acceptable method? It would minimize any impact to other existing boards.
Greg
In message 1628E43D99629C46988BE46087A3FBB94B48E7@ep-01.EmbeddedPlanet.local you wrote:
We currently have several PQII and PQIII PrPMC boards that dynamically support PCI bus speeds between 25 MHz and 133 MHz. These boards provide a CPLD register that gives PCI frequency. I would like to take advantage of this register, if possible, within u-boot rather than using a #define such as CONFIG_83XX_CLKIN, CONFIG_8260_CLKIN, or CONFIG_SYS_CLK_FREQ for the input clock frequency to the processor. Is there a suggested method of doing this?
Yes: don't change the code if there is no reeal need for it.
For testing I have implemented the following in get_sys_info() in speed.c for an MPC8560 board:
#if !defined (CONFIG_SYS_CLK_FREQ) sysInfo->freqSystemBus = plat_ratio * get_sys_clk(); #else sysInfo->freqSystemBus = plat_ratio * CONFIG_SYS_CLK_FREQ; #endif
A simple "#define CONFIG_SYS_CLK_FREQ get_sys_clk()" seems to be equivalent without need to change anything. Note that I didn't check all uses of the CONFIG_SYS_CLK_FREQ variable in the code.
The get_sys_clk() function resides in the board code directory. Would this be an acceptable method? It would minimize any impact to other existing boards.
What about my suggestion?
Best regards,
Wolfgang Denk
On Mar 8, 2006, at 5:49 PM, Wolfgang Denk wrote:
In message 1628E43D99629C46988BE46087A3FBB94B48E7@ep-01.EmbeddedPlanet.local you wrote:
We currently have several PQII and PQIII PrPMC boards that dynamically support PCI bus speeds between 25 MHz and 133 MHz. These boards provide a CPLD register that gives PCI frequency. I would like to take advantage of this register, if possible, within u-boot rather than using a #define such as CONFIG_83XX_CLKIN, CONFIG_8260_CLKIN, or CONFIG_SYS_CLK_FREQ for the input clock frequency to the processor. Is there a suggested method of doing this?
Yes: don't change the code if there is no reeal need for it.
For testing I have implemented the following in get_sys_info() in speed.c for an MPC8560 board:
#if !defined (CONFIG_SYS_CLK_FREQ) sysInfo->freqSystemBus = plat_ratio * get_sys_clk(); #else sysInfo->freqSystemBus = plat_ratio * CONFIG_SYS_CLK_FREQ; #endif
A simple "#define CONFIG_SYS_CLK_FREQ get_sys_clk()" seems to be equivalent without need to change anything. Note that I didn't check all uses of the CONFIG_SYS_CLK_FREQ variable in the code.
The get_sys_clk() function resides in the board code directory. Would this be an acceptable method? It would minimize any impact to other existing boards.
What about my suggestion?
This should work. It is how the CDS platform works. Take a look at board/cds/common/cadmus.c and include/configs/*CDS*.h
- kumar
participants (3)
-
Greg Davis -
Kumar Gala -
Wolfgang Denk