Simone
3cd1d6e0a6
The driver reached the PCU function's config space by walking the ACPI MCFG
table and mapping the ECAM page itself. That is one leaf driver deciding
config-space policy, and no other driver in mainline does it, so it was the
single most likely reason for a NAK.
Move that decision where it belongs: the upstream series is now two patches,
a PCI/x86 accessor that forces the memory-mapped path with the core's
locking, and this driver on top of it. Reviewers on each side now get
something they can act on, and get_maintainer.pl selects the PCI and x86
people by itself.
Correctness work in the same pass:
- the completion bits are latched, so a command the engine never accepted
was indistinguishable from a completed one and returned the previous
transaction's data as valid. Require a positive sign that the engine
acted on the command;
- compare the command registers after every transfer against what the
driver left in them and fail with -EAGAIN on a mismatch. The original
iMC driver had this check and it is what makes an unarbitrated system
detectable instead of silently wrong;
- use the i2c core's suspended-adapter mechanism rather than a private
flag and -EHOSTDOWN;
- use devm_mutex_init(), drop the unnecessary pci_enable_device(), and
return -ENODEV rather than -EPERM from the default-off gate, which was
printing a driver-core error on every boot;
- mask GO when restoring a saved command word.
Stop attributing the dropped CF8/CFC write to System Management Mode. The
only evidence was a boot log line naming the access method, which says
nothing about who filters the write. tools/probe-cf8-write.sh is there to
settle it with an MSR_SMI_COUNT measurement.
Add Documentation/i2c/busses/i2c-imc-skylake.rst, which every other PC SMBus
driver has and which was explicitly asked for on the 2020 iMC thread, the
tools/ scripts for the hardware measurements the submission still owes, and
compat/pci-mmcfg-compat.h so the driver still builds out-of-tree against a
kernel without the new accessor while the source stays byte-identical to the
submitted patch.
78 lines
2.7 KiB
Makefile
78 lines
2.7 KiB
Makefile
obj-m := i2c-imc-skylake.o
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KVER ?= $(shell uname -r)
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KDIR ?= /lib/modules/$(KVER)/build
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INSTALL_MOD_PATH ?= $(DESTDIR)
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INSTALL_MOD_DIR ?= updates
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PWD := $(shell pwd)
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# The driver calls pci_mmcfg_{read,write}_config(), added by patch 1/2 of the
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# upstream series. Against a kernel that does not have them yet, force-include
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# the out-of-tree shim so the driver source stays identical to the submitted
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# patch. See compat/pci-mmcfg-compat.h.
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IMC_NEED_COMPAT := $(shell grep -qs pci_mmcfg_read_config \
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$(srctree)/include/linux/pci.h || echo y)
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ifeq ($(IMC_NEED_COMPAT),y)
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ccflags-y += -include $(src)/compat/pci-mmcfg-compat.h
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$(warning i2c-imc-skylake: target kernel lacks pci_mmcfg_read_config(); building with the out-of-tree compat shim)
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endif
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all:
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$(MAKE) -C $(KDIR) M=$(PWD) modules
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clean:
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$(MAKE) -C $(KDIR) M=$(PWD) clean
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# Install through Kbuild so ownership, compression and destination follow the
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# target kernel/distribution policy. Invoke this target with suitable privileges.
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install: all
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$(MAKE) -C $(KDIR) M=$(PWD) modules_install \
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INSTALL_MOD_PATH=$(INSTALL_MOD_PATH) \
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INSTALL_MOD_DIR=$(INSTALL_MOD_DIR)
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# Remove a module installed in INSTALL_MOD_DIR. Invoke with suitable privileges.
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uninstall:
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rm -f $(INSTALL_MOD_PATH)/lib/modules/$(KVER)/$(INSTALL_MOD_DIR)/i2c-imc-skylake.ko*
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depmod -a -b $(INSTALL_MOD_PATH) $(KVER)
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# Runtime helpers require explicit acknowledgement of the firmware-arbitration
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# risk: make reload ALLOW_UNSAFE=1 (or make load ALLOW_UNSAFE=1).
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reload: all
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@test "$(ALLOW_UNSAFE)" = "1" || \
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{ echo "Refusing: rerun with ALLOW_UNSAFE=1" >&2; exit 2; }
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sudo rmmod i2c-imc-skylake 2>/dev/null || true
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sudo insmod i2c-imc-skylake.ko allow_unsafe_access=1
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# Load without build (use after install)
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load:
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@test "$(ALLOW_UNSAFE)" = "1" || \
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{ echo "Refusing: rerun with ALLOW_UNSAFE=1" >&2; exit 2; }
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sudo modprobe i2c-dev
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sudo modprobe i2c-imc-skylake allow_unsafe_access=1
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unload:
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sudo rmmod i2c-imc-skylake 2>/dev/null || true
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# Checkpatch (must be clean before submission)
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checkpatch:
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perl $(KDIR)/scripts/checkpatch.pl --strict --no-tree -f i2c-imc-skylake.c
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# Sparse static analysis (requires sparse >= kernel version; may show header errors on old sparse)
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sparse:
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$(MAKE) -C $(KDIR) M=$(PWD) C=1 CF="-D__CHECK_ENDIAN__"
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# Smoke test requires root or non-interactive sudo.
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test: all
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MODULE_PATH=$(PWD)/i2c-imc-skylake.ko bash test-smoke.sh
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# Hardware measurements that the upstream submission still needs. Read-only
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# unless explicitly asked otherwise; see tools/README.md.
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measure:
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@echo "Run the scripts under tools/ individually; see tools/README.md" >&2
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@false
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log:
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sudo dmesg | grep i2c-imc-skylake | tail -80
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.PHONY: all clean install uninstall reload load unload checkpatch sparse test measure log
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