Display001GfA/GfA-buildroot-libmodbus-GfA.patch

diff --git a/package/libmodbus/001-GfA-echo-rtu.patch b/package/libmodbus/001-GfA-echo-rtu.patch
new file mode 100644
index 0000000000..386172f970
--- /dev/null
+++ b/package/libmodbus/001-GfA-echo-rtu.patch
@@ -0,0 +1,105 @@
+diff -Naur a/src/modbus-rtu.c b/src/modbus-rtu.c
+--- a/src/modbus-rtu.c	2017-10-11 23:07:11.623017506 +0200
++++ b/src/modbus-rtu.c	2017-10-11 23:07:20.495035402 +0200
+@@ -257,6 +257,27 @@
+ }
+ #endif
+ 
++
++ssize_t _modbus_rtu_write_n_read(modbus_t *ctx, const uint8_t *req, int req_length) {
++ ssize_t w, r, i;
++ uint8_t rb[req_length];
++
++ // Transmit
++ w = write(ctx->s, req, req_length);
++
++ // Read back written bytes if hw has echo
++ r = 0;
++ while (r < w)
++  r += read(ctx->s, rb + r, w - r);
++ if (ctx->debug) {
++  for (i = 0; i < r; ++i)
++  fprintf(stderr, "|%02X|", rb[i]);
++  fprintf(stderr, "\n");
++ }
++
++ return w;
++}
++
+ ssize_t _modbus_rtu_send(modbus_t *ctx, const uint8_t *req, int req_length)
+ {
+ #if defined(_WIN32)
+@@ -264,7 +285,14 @@
+     DWORD n_bytes = 0;
+     return (WriteFile(ctx_rtu->w_ser.fd, req, req_length, &n_bytes, NULL)) ? n_bytes : -1;
+ #else
+-    return write(ctx->s, req, req_length);
++    modbus_rtu_t *ctx_rtu = ctx->backend_data;
++    ssize_t w;
++    
++    if(!ctx_rtu->echohw)    
++      w = write(ctx->s, req, req_length);
++     else
++      w = _modbus_rtu_write_n_read(ctx, req, req_length);
++    return w;
+ #endif
+ }
+ 
+@@ -772,6 +800,30 @@
+     }
+ }
+ 
++
++int modbus_rtu_set_echohw_mode(modbus_t* ctx, uint8_t mode) {
++ if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) {
++ modbus_rtu_t* rtu = (modbus_rtu_t*) ctx->backend_data;
++ rtu->echohw= mode;
++ return 0;
++ }
++ /* Wrong backend and invalid mode specified */
++ errno = EINVAL;
++ return -1;
++
++}
++
++int modbus_rtu_get_echohw_mode(modbus_t* ctx) {
++ if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) {
++ modbus_rtu_t* rtu = (modbus_rtu_t*) ctx->backend_data;
++ return rtu->echohw;
++ }
++ /* Wrong backend and invalid mode specified */
++ errno = EINVAL;
++ return -1;
++
++}
++
+ void _modbus_rtu_close(modbus_t *ctx)
+ {
+     /* Closes the file descriptor in RTU mode */
+diff -Naur a/src/modbus-rtu.h b/src/modbus-rtu.h
+--- a/src/modbus-rtu.h	2017-10-11 23:07:11.623017506 +0200
++++ b/src/modbus-rtu.h	2017-10-11 23:07:20.495035402 +0200
+@@ -37,6 +37,12 @@
+ int modbus_rtu_set_serial_mode(modbus_t *ctx, int mode);
+ int modbus_rtu_get_serial_mode(modbus_t *ctx);
+ 
++#define MODBUS_RTU_HAS_ECHOHW 1
++#define MODBUS_RTU_NO_ECHOHW 0
++
++int modbus_rtu_set_echohw_mode(modbus_t *ctx, uint8_t mode);
++int modbus_rtu_get_echohw_mode(modbus_t *ctx);
++
+ MODBUS_END_DECLS
+ 
+ #endif /* _MODBUS_RTU_H_ */
+diff -Naur a/src/modbus-rtu-private.h b/src/modbus-rtu-private.h
+--- a/src/modbus-rtu-private.h	2017-10-11 23:07:11.623017506 +0200
++++ b/src/modbus-rtu-private.h	2017-10-11 23:07:20.495035402 +0200
+@@ -81,6 +81,7 @@
+ #if HAVE_DECL_TIOCSRS485
+     int serial_mode;
+ #endif
++    uint8_t echohw;
+ } modbus_rtu_t;
+ 
+ #endif /* _MODBUS_RTU_PRIVATE_H_ */