Here are another set of ESCC fixes from my attempts to boot MacOS on the q800 machine.
Patch 1 fixes up the formatting so that the remainder of the patchset keeps checkpatch happy. Patches 2-8 rework the reset handling so that the QEMU device reset is separate from the ESCC in-built hardware and software reset as defined in the datasheet. The aim here is two-fold: allow QEMU's device reset to place the ESCC device in a known state (although we assume all registers are zeroed whilst their values are undefined according to the datasheet) and ensure that the reset commands sent by the MacOS OpenTransport extension on boot don't re-assert the active low STATUS_SYNC bit in R_STATUS. Finally patch 9 is the real fix: when entering SDLC mode using an "Enter hunt" command the STATUS_SYNC bit in R_STATUS must remain high until the flag byte is detected. Without this fix the active low STATUS_SYNC is continually asserted causing the MacOS OpenTransport extension to hang on startup as it believes it is constantly receiving LocalTalk traffic during its initial negotiation phase. NOTE: this patchset currently fails CI because it exposed a bug that OpenBIOS doesn't send ESCC channel reset commands before attempting to configure and use the serial port. Those patches have just been posted to the OpenBIOS mailing list here: https://mail.coreboot.org/hyperkitty/list/openb...@openbios.org/thread/PQCW5RDIDIEUYBVAHNIY3OMHCEVYYWPU/. Signed-off-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk> v2: - Rebase onto master - Rewrite cover letter to cover new reset changes - Change reset to separate out QEMU device reset, soft reset and hard reset (ensuring register values are updated as specified in the datasheet) - Add R-B tags from Peter Mark Cave-Ayland (9): escc: checkpatch fixes escc: reset register values to zero in escc_reset() escc: introduce escc_soft_reset_chn() for software reset escc: introduce escc_hard_reset_chn() for hardware reset escc: implement soft reset as described in the datasheet escc: implement hard reset as described in the datasheet escc: remove register changes from escc_reset_chn() escc: re-use escc_reset_chn() for hard and soft reset escc: fix STATUS_SYNC bit in R_STATUS register hw/char/escc.c | 281 ++++++++++++++++++++++++++++++++++--------------- 1 file changed, 197 insertions(+), 84 deletions(-) -- 2.20.1
