On Thu, Jan 11, 2024 at 09:55:40AM +0100, Philipp Stanner wrote:
The implementation of pci_iounmap() is currently scattered over two files, drivers/pci/iomap.c and lib/iomap.c. Additionally, architectures can define their own version.
To have only one version, it's necessary to create a helper function, iomem_is_ioport(), that tells pci_iounmap() whether the passed address points to an ioport or normal memory.
iomem_is_ioport() can be provided through two different ways:
- The architecture itself provides it. As of today, the version coming from lib/iomap.c de facto is the x86-specific version and comes into play when CONFIG_GENERIC_IOMAP is selected. This rather confusing naming is an artifact left by the removal of IA64.
- As a default version in include/asm-generic/io.h for those architectures that don't use CONFIG_GENERIC_IOMAP, but also don't provide their own version of iomem_is_ioport().
Once all architectures that support ports provide iomem_is_ioport(), the arch-specific definitions for pci_iounmap() can be removed and the archs can use the generic implementation, instead.
Create a unified version of pci_iounmap() in drivers/pci/iomap.c. Provide the function iomem_is_ioport() in include/asm-generic/io.h (generic) and lib/iomap.c ("pseudo-generic" for x86).
Remove the CONFIG_GENERIC_IOMAP guard around ARCH_WANTS_GENERIC_PCI_IOUNMAP so that configs that set CONFIG_GENERIC_PCI_IOMAP without CONFIG_GENERIC_IOMAP still get the function.
Add TODOs for follow-up work on the "generic is not generic but x86-specific"-Problem. ...
+++ b/drivers/pci/iomap.c @@ -135,44 +135,30 @@ void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long maxlen) EXPORT_SYMBOL_GPL(pci_iomap_wc); /*
- pci_iounmap() somewhat illogically comes from lib/iomap.c for the
- CONFIG_GENERIC_IOMAP case, because that's the code that knows about
- the different IOMAP ranges.
- This check is still necessary due to legacy reasons.
- But if the architecture does not use the generic iomap code, and if
- it has _not_ defined it's own private pci_iounmap function, we define
- it here.
- NOTE! This default implementation assumes that if the architecture
- support ioport mapping (HAS_IOPORT_MAP), the ioport mapping will
- be fixed to the range [ PCI_IOBASE, PCI_IOBASE+IO_SPACE_LIMIT [,
- and does not need unmapping with 'ioport_unmap()'.
- If you have different rules for your architecture, you need to
- implement your own pci_iounmap() that knows the rules for where
- and how IO vs MEM get mapped.
- This code is odd, and the ARCH_HAS/ARCH_WANTS #define logic comes
- from legacy <asm-generic/io.h> header file behavior. In particular,
- it would seem to make sense to do the iounmap(p) for the non-IO-space
- case here regardless, but that's not what the old header file code
- did. Probably incorrectly, but this is meant to be bug-for-bug
- compatible.
Moving this comment update to the patch that adds the ioport_unmap() call would make that patch more consistent and simplify this patch.
- TODO: Have all architectures that provide their own pci_iounmap() provide
*/
- iomem_is_ioport() instead. Remove this #if afterwards.
#if defined(ARCH_WANTS_GENERIC_PCI_IOUNMAP) -void pci_iounmap(struct pci_dev *dev, void __iomem *p) +/**
- pci_iounmap - Unmapp a mapping
- @dev: PCI device the mapping belongs to
- @addr: start address of the mapping
- Unmapp a PIO or MMIO mapping.
s/Unmapp/Unmap/ (twice)
- */
+void pci_iounmap(struct pci_dev *dev, void __iomem *addr)
Maybe move the "p" to "addr" rename to the patch that fixes the pci_iounmap() #ifdef problem, since that's a trivial change that already has to do with handling both PIO and MMIO? Then this patch would be a little more focused.
The kernel-doc addition could possibly also move there since it isn't related to the unification.
{ -#ifdef ARCH_HAS_GENERIC_IOPORT_MAP
- uintptr_t start = (uintptr_t) PCI_IOBASE;
- uintptr_t addr = (uintptr_t) p;
- if (addr >= start && addr < start + IO_SPACE_LIMIT) {
ioport_unmap(p);+#ifdef CONFIG_HAS_IOPORT_MAP
- if (iomem_is_ioport(addr)) {
ioport_unmap(addr);#endif
- iounmap(p);
- iounmap(addr);
}
- If CONFIG_GENERIC_IOMAP is selected and the architecture does NOT provide its
- own version, ARCH_WANTS_GENERIC_IOMEM_IS_IOPORT makes sure that the generic
- version from asm-generic/io.h is NOT used and instead the second "generic"
- version from this file here is used.
- There are currently two generic versions because of a difficult cleanup
- process. Namely, the version in lib/iomap.c once was really generic when IA64
- still existed. Today, it's only really used by x86.
- TODO: Move this function to x86-specific code.
Some of these TODOs look fairly simple. Are they actually hard, or could they just be done now?
It seems like implementing iomem_is_ioport() for the other arches would be straightforward and if done first, could make this patch look tidier.
Or if the TODOs can't be done now, maybe the iomem_is_ioport() addition could be done as a separate patch to make the unification more obvious.
- */
+#if defined(ARCH_WANTS_GENERIC_IOMEM_IS_IOPORT) +bool iomem_is_ioport(void __iomem *addr) {
- IO_COND(addr, /* nothing */, iounmap(addr));
- unsigned long port = (unsigned long __force)addr;
- if (port > PIO_OFFSET && port < PIO_RESERVED)
return true;- return false;
} -EXPORT_SYMBOL(pci_iounmap); -#endif /* CONFIG_PCI */
+#endif /* ARCH_WANTS_GENERIC_IOMEM_IS_IOPORT */
2.43.0