fw: simplify how to enable QEMU debug in firmware.

- Remove the define `NOCONSOLE`, add define `QEMU_CONSOLE`
- Inverse the use of it, add the define to have QEMU debug output in fw.
- Add a make target `qemu_firmware.elf` which builds the firmware with
  QEMU console enabled.

Co-authored-by: Mikael Ågren <mikael@tillitis.se>

hw/application_fpga/Makefile

@@ -44,7 +44,7 @@ CC = clang
 CFLAGS = -target riscv32-unknown-none-elf -march=rv32iczmmul -mabi=ilp32 \
    -static -std=gnu99 -O2 -ffast-math -fno-common -fno-builtin-printf \
    -fno-builtin-putchar -fno-builtin-memcpy -nostdlib -mno-relax -Wall \
-   -Wpedantic -Wno-language-extension-token -flto -g -DNOCONSOLE
+   -Wpedantic -Wno-language-extension-token -flto -g
 
 AS = clang
 ASFLAGS = -target riscv32-unknown-none-elf -march=rv32iczmmul -mabi=ilp32 -mno-relax
@@ -151,6 +151,10 @@ $(TESTFW_OBJS): $(FIRMWARE_DEPS)
 firmware.elf: $(FIRMWARE_OBJS) $(P)/fw/tk1/firmware.lds
 	$(CC) $(CFLAGS) $(FIRMWARE_OBJS) $(LDFLAGS) -o $@
 
+qemu_firmware.elf: CFLAGS += -DQEMU_CONSOLE
+qemu_firmware.elf: firmware.elf
+	mv firmware.elf qemu_firmware.elf
+
 .PHONY: check
 check:
 	clang-tidy -header-filter=.* -checks=cert-* $(FIRMWARE_SOURCES) -- $(CFLAGS)
@@ -359,6 +363,7 @@ clean_fw:
 	rm -f $(FIRMWARE_OBJS)
 	rm -f testfw.{elf,elf.map,bin,hex}
 	rm -f $(TESTFW_OBJS)
+	rm -f qemu_firmware.elf
 .PHONY: clean_fw
 
 #-------------------------------------------------------------------

hw/application_fpga/fw/README.md

@@ -286,11 +286,12 @@ for the tools you need. The easiest is probably to use your OCI image,
 also useful for debugging the firmware. You can attach GDB, use
 breakpoints, et cetera.
 
-If you want to use plain debug prints you can remove `-DNOCONSOLE`
-from the `CFLAGS` in the Makefile and using the helper functions in
-`lib.c` like `htif_puts()` `htif_putinthex()` `htif_hexdump()` and
-friends for printf-like debugging. Note that these functions are only
-usable in qemu.
+There is a special make target for QEMU: `qemu_firmware.elf`, which
+sets `-DQEMU_CONSOLE`, so you can use plain debug prints using the
+helper functions in `lib.c` like `htif_puts()` `htif_putinthex()`
+`htif_hexdump()` and friends. Note that these functions are only
+usable in qemu and that you might need to `make clean` before
+building, if you have already built before.
 
 ### Test firmware
 

hw/application_fpga/fw/tk1/lib.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022 - Tillitis AB
+ * Copyright (C) 2022-2024 - Tillitis AB
  * SPDX-License-Identifier: GPL-2.0-only
  */
 
@@ -7,7 +7,7 @@
 #include "assert.h"
 #include "types.h"
 
-#ifndef NOCONSOLE
+#ifdef QEMU_CONSOLE
 struct {
 	uint32_t arr[2];
 } static volatile tohost __attribute__((section(".htif")));

hw/application_fpga/fw/tk1/lib.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022 - Tillitis AB
+ * Copyright (C) 2022-2024 - Tillitis AB
  * SPDX-License-Identifier: GPL-2.0-only
  */
 
@@ -8,21 +8,21 @@
 
 #include "types.h"
 
-#ifdef NOCONSOLE
-#define htif_putc(ch)
-#define htif_lf()
-#define htif_puthex(c)
-#define htif_putinthex(n)
-#define htif_puts(s)
-#define htif_hexdump(buf, len)
-#else
+#ifdef QEMU_CONSOLE 
 void htif_putc(char ch);
 void htif_lf();
 void htif_puthex(uint8_t c);
 void htif_putinthex(const uint32_t n);
 void htif_puts(const char *s);
 void htif_hexdump(void *buf, int len);
-#endif
+#else
+#define htif_putc(ch)
+#define htif_lf()
+#define htif_puthex(c)
+#define htif_putinthex(n)
+#define htif_puts(s)
+#define htif_hexdump(buf, len)
+#endif /* QEMU_CONSOLE */
 
 void *memset(void *dest, int c, unsigned n);
 void memcpy_s(void *dest, size_t destsize, const void *src, size_t n);