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base repository: whitequark/glasgow
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head repository: whitequark/glasgow
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compare: 9cc3d9a48161
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  • 3 commits
  • 2 files changed
  • 1 contributor

Commits on Feb 26, 2019

  1. applet.jtag_mips: reset Rocc before entering probe mode. 

    Otherwise all our writes will just get ignored.

This commit also adds detection of unexpected core reset.
    @whitequark
    whitequark committed Feb 26, 2019
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    034d01f View commit details

Commits on Feb 27, 2019

  1. applet.jtag: reset TAP chain before selecting a TAP. 

    Selecting a TAP requires reading IDCODE/BYPASS from DR, which means
that a TAP chain reset was a precondition for select_tap(), but this
wasn't intended or documented. The current design requires a reset,
so just add that.

Since all derived applets want to select a TAP, remove the TAP reset
via TMS from run(); however, keep TAP reset via TRST#, because that
enables the TRST# driver.
    @whitequark
    whitequark committed Feb 27, 2019
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    fef9fff View commit details

  2. applet.jtag: enumerate-ir: handle incorrect TAP selection.

    @whitequark
    whitequark committed Feb 27, 2019
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    9cc3d9a View commit details
Showing with 16 additions and 5 deletions.
  1. +8 −1 software/glasgow/applet/jtag/__init__.py
  2. +8 −4 software/glasgow/applet/jtag_mips/__init__.py
9 changes: 8 additions & 1 deletion software/glasgow/applet/jtag/__init__.py
View file
Original file line number Diff line number Diff line change
@@ -547,6 +547,8 @@ def segment_irs(self, ir_value, count=None):
return irs

async def select_tap(self, tap, max_ir_length=128, max_dr_length=1024):
await self.test_reset()

dr_value = await self.scan_dr(max_dr_length)
if dr_value is None:
return
@@ -666,8 +668,8 @@ async def run(self, device, args, reset=True):
iface = await device.demultiplexer.claim_interface(self, self.mux_interface, args)
jtag_iface = JTAGInterface(iface, self.logger)
if reset:
# If we have a defined TRST#, enable the driver and reset the TAPs to a good state.
await jtag_iface.pulse_trst()
await jtag_iface.test_reset()
return jtag_iface

@classmethod
@@ -724,6 +726,8 @@ def add_interact_arguments(cls, parser):

async def interact(self, device, args, jtag_iface):
if args.operation in ("scan", "enumerate-ir"):
await jtag_iface.test_reset()

dr_value = await jtag_iface.scan_dr(max_length=args.max_dr_length)
if dr_value is None:
self.logger.warning("DR length scan did not terminate")
@@ -774,6 +778,9 @@ async def interact(self, device, args, jtag_iface):

tap_iface = await jtag_iface.select_tap(tap_index,
args.max_ir_length, args.max_dr_length)
if not tap_iface:
raise GlasgowAppletError("cannot select TAP #%d" % tap_index)

for ir_value in range(0, (1 << ir_length)):
ir_value = bitarray([ir_value & (1 << bit) for bit in range(ir_length)],
endian="little")
12 changes: 8 additions & 4 deletions software/glasgow/applet/jtag_mips/__init__.py
View file
Original file line number Diff line number Diff line change
@@ -66,10 +66,13 @@ async def _exchange_control(self, **fields):
await self.lower.write_ir(IR_CONTROL)

control_bits = await self.lower.exchange_dr(control_bits)
control = DR_CONTROL.from_bitarray(control_bits)
self._log("read CONTROL %s", control.bits_repr(omit_zero=True))
new_control = DR_CONTROL.from_bitarray(control_bits)
self._log("read CONTROL %s", new_control.bits_repr(omit_zero=True))

return control
if new_control.Rocc and control.Rocc:
raise GlasgowAppletError("target has been unexpectedly reset")

return new_control

async def _enable_probe(self):
self._control.ProbEn = 1
@@ -197,7 +200,8 @@ async def _probe(self):
self._DRSEG_DBMn_addr = DRSEG_DBMn_addr
self._DRSEG_DBVn_addr = DRSEG_DBVn_addr

control = await self._exchange_control()
# Start by acknowledging any reset.
control = await self._exchange_control(Rocc=0)
if control.DM:
raise GlasgowAppletError("target already in debug mode")