[U-Boot-Users] Proposal to add "ispeed" (I2C speed) command

[Stephan Linz <linz@mazet.de>]

Hi Tolunay,

Am Mittwoch,  3. M?rz 2004 18:36 schrieb listmember at orkun.us:
> We have some instrumentation hanging on I2C bus. I would like to introduce
> a new u-boot command ispeed to set the i2c speed so fast devices would not
> be constrained to the lowest denominator speed.

Makes sense, but why do you need measuring datas in context of a bootloader ?

>
> If desired we can make be conditionally included if CONFIG_CMD_ISPEED
> (suggestions?) so it would not take space when it is not needed (or
> desired) on a particular board. The proposed syntax would be.
>
> ispeed {i2c bus speed}
>
> Since u-boot uses hex: 100kHz => 186A0, 400kHz => 61A80

Hm, I think you should expand the command syntax -- ex.:

ispeed [i2c_bus_speed_in_hz]


Without a argument 'ispeed' gets back the current setting.

With an argument 'ispeed' converts the given string to ulong and setup the 
new speed. The argument can be a decimal integer, because simple_strtoul() 
from lib_generic/vsprintf.c understands base option 10.

> I would also set an environment variable in ispeed command indicating
> current i2c speed ("i2cspeed") so it could be used in scripts.

Is it really needed ... I don't think so. You can read back the current 
setting with 'ispeed' and save the result into a environment variable of 
your choice. So you can use it again in another or the same script.


Best Regards,
Stephan Linz