MySQL retrieve column names where datatype == X

I need to write some code that applies to only certain fields within our database. Specifically I'm looking for any field in all tables of a single database that are of type DECIMAL(12,5);

If it's of any help, all of our decimal fields are prefixed with dec_. I could gather all of the decimal fields from all tables, but there are tons of them that don't match my particular criteria, I need only the decimal values who's limit is 12,5.

I'd have no preference between doing this in pure SQL, or using PHP. We're currently using the CakePHP framework to manage our project, though I could just as easily do this without using the framework. This is a one time operation to gather the required data so I can continue forward with the audit.

Any help is greatly appreciated, thank you for taking the time to read this.

[EDIT] Got some great answers here, thanks everyone! I probably should have mentioned this in my initial post, but is there any way I can also get the table name associated with each field?