serprog: Add support for setting the SPI frequency

Introduce a new opcode (0x14) that sends the requested frequency as a 32b
long value in Hertz to the programmer and receives the frequency eventually
chosen by the programmer. The user can specify this with the programmer
parameter "spispeed" (named after the similar parameter for the buspirate)
including an optional suffix of 'M' or 'k' for specifying megahertz or kilohertz
respectively (lowercase suffixes are also accepted).

Thanks to Idwer and Uwe (and maybe others) for their feedback especially
regarding the unit of frequency to use.

Corresponding to flashrom svn r1571.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>

1 files changed, 11 insertions, 1 deletions

diff --git a/flashrom.8 b/flashrom.8
index 93df1a2..f37d5e9 100644
--- a/flashrom.8
+++ b/flashrom.8
@@ -598,7 +598,17 @@ syntax and for IP, you have to use
 .sp
 .B "  flashrom \-p serprog:ip=ipaddr:port"
 .sp
-instead. More information about serprog is available in
+instead. In case the device supports it, you can set the SPI clock frequency
+with the optional
+.B spispeed
+parameter. The frequency is parsed as Hertz, unless an
+.BR M ", or " k
+suffix is given, then megahertz or kilohertz are used respectively.
+Example that sets the frequency to 2 MHz:
+.sp
+.B "flashrom \-p serprog:dev=/dev/device:baud,spispeed=2M"
+.sp
+More information about serprog is available in
 .B serprog-protocol.txt
 in the source distribution.
 .SS