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There is no DMA in Quadra 800, so the CPU reads/writes the data from the
PDMA register (offset 0x100, ESP_PDMA in hw/m68k/q800.c) and copies them
to/from the memory.
There is a nice assembly loop in the kernel to do that, see
linux/drivers/scsi/mac_esp.c:MAC_ESP_PDMA_LOOP().
The start of the transfer is triggered by the DREQ interrupt (see linux
mac_esp_send_pdma_cmd()), the CPU polls on the IRQ flag to start the
transfer after a SCSI command has been sent (in Quadra 800 it goes
through the VIA2, the via2-irq line and the vIFR register)
The Macintosh hardware includes hardware handshaking to prevent the CPU
from reading invalid data or writing data faster than the peripheral
device can accept it.
This is the "blind mode", and from the doc:
"Approximate maximum SCSI transfer rates within a blocks are 1.4 MB per
second for blind transfers in the Macintosh II"
Some references can be found in:
Apple Macintosh Family Hardware Reference, ISBN 0-201-19255-1
Guide to the Macintosh Family Hardware, ISBN-0-201-52405-8
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Co-developed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20191026164546.30020-4-laurent@vivier.eu>
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The guest OS reads RSTAT, RSEQ, and RINTR, and expects those registers
to reflect a consistent state. However, it is possible that the registers
can change after RSTAT was read, but before RINTR is read, when
esp_command_complete() is called.
Guest OS qemu
-------- ----
[handle interrupt]
Read RSTAT
esp_command_complete()
RSTAT = STAT_ST
esp_dma_done()
RSTAT |= STAT_TC
RSEQ = 0
RINTR = INTR_BS
Read RSEQ
Read RINTR RINTR = 0
RSTAT &= ~STAT_TC
RSEQ = SEQ_CD
The guest OS would then try to handle INTR_BS combined with an old
value of RSTAT. This sometimes resulted in lost events, spurious
interrupts, guest OS confusion, and stalled SCSI operations.
A typical guest error log (observed with various versions of Linux)
looks as follows.
scsi host1: Spurious irq, sreg=13.
...
scsi host1: Aborting command [84531f10:2a]
scsi host1: Current command [f882eea8:35]
scsi host1: Queued command [84531f10:2a]
scsi host1: Active command [f882eea8:35]
scsi host1: Dumping command log
scsi host1: ent[15] CMD val[44] sreg[90] seqreg[00] sreg2[00] ireg[20] ss[00] event[0c]
scsi host1: ent[16] CMD val[01] sreg[90] seqreg[00] sreg2[00] ireg[20] ss[02] event[0c]
scsi host1: ent[17] CMD val[43] sreg[90] seqreg[00] sreg2[00] ireg[20] ss[02] event[0c]
scsi host1: ent[18] EVENT val[0d] sreg[92] seqreg[04] sreg2[00] ireg[18] ss[00] event[0c]
...
Defer handling command completion until previous interrupts have been
handled to fix the problem.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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Remove the legacy esp_init() function now that there are no more remaining
users.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20180613094727.11326-3-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Hervé Poussineau <hpoussin@reactos.org>
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The global hack for creating SCSI devices has recently been removed,
but this apparently broke SCSI devices on some boards that were not
ready for this change yet. For the pica61 machine you now get:
$ mips64-softmmu/qemu-system-mips64 -M pica61 -cdrom x.iso
qemu-system-mips64: -cdrom x.iso: machine type does not support if=scsi,bus=0,unit=2
Fix it by calling scsi_bus_legacy_handle_cmdline() after creating the
corresponding SCSI controller.
Fixes: 1454509726719e0933c800fad00d6999752688ea
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1520414644-11535-1-git-send-email-thuth@redhat.com>
Reviewed-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This enables them to be used outside of esp.c.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
CC: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Artyom Tarasenko <atar4qemu@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
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While doing DMA read into ESP command buffer 's->cmdbuf', it could
write past the 's->cmdbuf' area, if it was transferring more than 16
bytes. Increase the command buffer size to 32, which is maximum when
's->do_cmd' is set, and add a check on 'len' to avoid OOB access.
Reported-by: Li Qiang <liqiang6-s@360.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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After a reset ESP_TCHI should contain the unique ID
of the chip. This value will be overwritten with the
current tranfer count if the transfer count has
previously been set.
So we should always return the chip id if ESP_TCHI
has never been written to.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Many of these should be cleaned up with proper qdev-/QOM-ification.
Right now there are many catch-all headers in include/hw/ARCH depending
on cpu.h, and this makes it necessary to compile these files per-target.
However, fixing this does not belong in these patches.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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