Fix upstream j1939, xcp, kwp

[BenGardiner]

Various fixes cherry-picked out of more elaborate J1939 based stuff on RAMN that isn't ready to see light of day yet.

[github-actions]

🔨 Build & Macro Coverage Report

Default Builds — Hex File Sizes

ECU	Debug (tag 15.0)	Debug (tag 2.1.1)	Release (tag 15.0)	Release (tag 2.1.1)
ECUA	544 KiB (557127 bytes)	544 KiB (557082 bytes)	367 KiB (376316 bytes)	367 KiB (376263 bytes)
ECUB	363 KiB (372451 bytes)	363 KiB (372451 bytes)	216 KiB (222166 bytes)	216 KiB (221671 bytes)
ECUC	345 KiB (353325 bytes)	345 KiB (353325 bytes)	196 KiB (201593 bytes)	196 KiB (201082 bytes)
ECUD	354 KiB (363053 bytes)	354 KiB (363053 bytes)	204 KiB (209063 bytes)	203 KiB (208748 bytes)

Macro Coverage Build Results

Variant	Macros Changed	Result	Warnings
gsusb	+ENABLE_GSUSB	✅ Pass	5
gsusb_and_bb	+ENABLE_GSUSB +ENABLE_BITBANG	✅ Pass	5
i2c	+ENABLE_I2C	✅ Pass	5
j1939	+DEFAULT_TRAFFIC_MODE=TRAFFIC_MODE_J1939	✅ Pass	5
j1939_showcase_mode	+DEFAULT_TRAFFIC_MODE=TRAFFIC_MODE_J1939 +RAMN_SHOWCASE_MODE	✅ Pass	5
kwp	+ENABLE_KWP	✅ Pass	5
no_debug	−ENABLE_USB_DEBUG −ENABLE_JOYSTICK_CONTROLS −ENABLE_SCREEN −ENABLE_CHIP8 −GENERATE_RUNTIME_STATS	✅ Pass	5
no_dynamic_bitrate	−ENABLE_DYNAMIC_BITRATE	✅ Pass	5
no_extras	−ENABLE_J1979 −ENABLE_MINICTF −ENABLE_CHIP8 −ENABLE_SCREEN −ENABLE_SPI	✅ Pass	5
no_uds	−ENABLE_UDS −ENABLE_UDS_REPROGRAMMING	✅ Pass	6
uart	+ENABLE_UART −ENABLE_CDC −ENABLE_USB	✅ Pass	5
usb_autodetect	+ENABLE_USB_AUTODETECT	✅ Pass	5
watchdog	+WATCHDOG_ENABLE	✅ Pass	5

Source Code Compile Coverage

• Total .c source lines: 21780
• Lines compiled in ≥1 configuration: 20642 (~95%)
• ENABLE_ macro coverage: 22/22 (100.0%) macros tested in both ON and OFF states

Full ENABLE_ Macro Coverage Table

#	Macro	Tested ON	Tested OFF	Covered
1	ENABLE_ADC	default (ECUB, ECUC, ECUD)	default (ECUA)	✅
2	ENABLE_BITBANG	default (ECUA), variant: gsusb_and_bb	default (ECUB, ECUC, ECUD)	✅
3	ENABLE_CDC	default (ECUA)	default (ECUB, ECUC, ECUD), variant: uart	✅
4	ENABLE_CHIP8	default (ECUA)	default (ECUB, ECUC, ECUD), variant: no_debug, variant: no_extras	✅
5	ENABLE_DYNAMIC_BITRATE	default (ECUA, ECUB, ECUC, ECUD)	variant: no_dynamic_bitrate	✅
6	ENABLE_GSUSB	variant: gsusb, variant: gsusb_and_bb	default (ECUA, ECUB, ECUC, ECUD)	✅
7	ENABLE_I2C	variant: i2c	default (ECUA, ECUB, ECUC, ECUD)	✅
8	ENABLE_J1979	default (ECUA, ECUB, ECUC, ECUD)	variant: no_extras	✅
9	ENABLE_JOYSTICK_CONTROLS	default (ECUA)	default (ECUB, ECUC, ECUD), variant: no_debug	✅
10	ENABLE_KWP	variant: kwp	default (ECUA, ECUB, ECUC, ECUD)	✅
11	ENABLE_MINICTF	default (ECUA, ECUD)	default (ECUB, ECUC), variant: no_extras	✅
12	ENABLE_SCREEN	default (ECUA)	default (ECUB, ECUC, ECUD), variant: no_debug, variant: no_extras	✅
13	ENABLE_SPI	default (ECUA, ECUD)	default (ECUB, ECUC), variant: no_extras	✅
14	ENABLE_UART	variant: uart	default (ECUA, ECUB, ECUC, ECUD)	✅
15	ENABLE_UDS	default (ECUA, ECUB, ECUC, ECUD)	variant: no_uds	✅
16	ENABLE_UDS_REPROGRAMMING	default (ECUA, ECUB, ECUC, ECUD)	variant: no_uds	✅
17	ENABLE_USB	default (ECUA)	default (ECUB, ECUC, ECUD), variant: uart	✅
18	ENABLE_USB_AUTODETECT	variant: usb_autodetect	default (ECUA, ECUB, ECUC, ECUD)	✅
19	ENABLE_USB_DEBUG	default (ECUA)	default (ECUB, ECUC, ECUD), variant: no_debug	✅
20	ENABLE_XCP	default (ECUB, ECUC, ECUD)	default (ECUA)	✅
21	GENERATE_RUNTIME_STATS	default (ECUA, ECUB, ECUC, ECUD)	variant: no_debug	✅
22	WATCHDOG_ENABLE	variant: watchdog	default (ECUA, ECUB, ECUC, ECUD)	✅