\# Author Andy Pugh
\# Issued under the terms of the GPL v2 License or any later version

.TH hm2_bspi_set_read_function "3hm2" "2011-05-31" "LinuxCNC Documentation" "Hostmot2"
.SH NAME

hm2_bspi_set_read_function \- Register a function to handle the tram write phase of a hostmot2 buffered SPI driver. 
.SH SYNTAX
.nf
.B #include <hostmot2-serial.h>
.HP
int hm2_bspi_set_read_function(char *name, void *func, void *subdata)

.SH DESCRIPTION
\fBhm2_bspi_set_read_function\fR registers a function in an external driver
to be called every time that the main Hostmot2 driver calls the generic "process_tram_read" function.
The names of the available channels are printed with rtapi_print_msg during the driver loading process and take the form:
.RS
hm2_<board name>.<board index>.bspi.<index>
.RE
For example hm2_5i23.0.bspi.0.

"func" should be a pointer to a function in the sub driver
which is to be called to process the results of the BSPI TRAM read phase.
The function must take a single argument, a pointer to an individual instance of the internal driver.
If defined in comp then the function must \fBnot\fP use the FUNCTION() convenience macro,
and the argument to the function in the definition  must \fBalways\fP be (struct state *inst).

"subdata" is a pointer to the driver instance internal data.
In the case of a driver written in comp this will always be "inst" in the function call and
the call should be anywhere in the EXTRA_SETUP code. 

.SH REALTIME CONSIDERATIONS
Call only from realtime init code, not from other realtime code or non-realtime components.

.SH RETURN VALUE
Returns 0 on success and \-1 on failure.

.SH SEE ALSO
\fBhm2_allocate_bspi_tram(3hm2)\fR,
\fBhm2_bspi_setup_chan(3hm2)\fR,
\fBhm2_bspi_set_write_function(3hm2)\fR,
\fBhm2_bspi_write_chan(3hm2)\fR,
\fBhm2_tram_add_bspi_frame(3hm2)\fR,
src/hal/drivers mesa_7i65.comp in the LinuxCNC source distribution.
