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[WIP] LoongArch: Add ACPI compatibility for ISA I/O space reservation #19

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[WIP] LoongArch: Add ACPI compatibility for ISA I/O space reservation #19

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63 changes: 38 additions & 25 deletions arch/loongarch/kernel/setup.c
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Original file line number Diff line number Diff line change
Expand Up @@ -510,36 +510,49 @@ static int __init add_legacy_isa_io(struct fwnode_handle *fwnode,
static __init int arch_reserve_pio_range(void)
{
struct device_node *np;
struct fwnode_handle *fwnode;

for_each_node_by_name(np, "isa") {
struct of_range range;
struct of_range_parser parser;
if (acpi_disabled) {
for_each_node_by_name(np, "isa") {
struct of_range range;
struct of_range_parser parser;

pr_info("ISA Bridge: %pOF\n", np);
pr_info("ISA Bridge: %pOF\n", np);

if (of_range_parser_init(&parser, np)) {
pr_info("Failed to parse resources.\n");
of_node_put(np);
break;
}

for_each_of_range(&parser, &range) {
switch (range.flags & IORESOURCE_TYPE_BITS) {
case IORESOURCE_IO:
pr_info(" IO 0x%016llx..0x%016llx -> 0x%016llx\n",
range.cpu_addr,
range.cpu_addr + range.size - 1,
range.bus_addr);
if (add_legacy_isa_io(&np->fwnode, range.cpu_addr, range.size))
pr_warn("Failed to reserve legacy IO in Logic PIO\n");
break;
case IORESOURCE_MEM:
pr_info(" MEM 0x%016llx..0x%016llx -> 0x%016llx\n",
range.cpu_addr,
range.cpu_addr + range.size - 1,
range.bus_addr);
if (of_range_parser_init(&parser, np)) {
pr_info("Failed to parse resources.\n");
of_node_put(np);
break;
}

for_each_of_range(&parser, &range) {
switch (range.flags & IORESOURCE_TYPE_BITS) {
case IORESOURCE_IO:
pr_info(" IO 0x%016llx..0x%016llx -> 0x%016llx\n",
range.cpu_addr,
range.cpu_addr + range.size - 1,
range.bus_addr);
if (add_legacy_isa_io(&np->fwnode, range.cpu_addr, range.size))
pr_warn("Failed to reserve legacy IO in Logic PIO\n");
break;
case IORESOURCE_MEM:
pr_info(" MEM 0x%016llx..0x%016llx -> 0x%016llx\n",
range.cpu_addr,
range.cpu_addr + range.size - 1,
range.bus_addr);
break;
}
}
}
} else {
fwnode = acpi_alloc_fwnode_static();
if (!fwnode) {
pr_warn("Failed to allocate fwnode for legacy ISA\n");
return 0;
}
if (add_legacy_isa_io(fwnode, LOONGSON_LIO_BASE, ISA_IOSIZE)) {
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@xry111 xry111 Jan 16, 2026 •
edited
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I don't think this patch can be merged as-is.

Both 7A1000 and 7A2000 manuals state that 0x18000000-0x1800ffff (64K) is for "LPC I/O", but this patch reserves 0x18000000-0x18003fff (16K). The only reference I can find about this 16K range is the 2K1000 ISA controller which is obviously unrelated to any desktop platform. The macro name ("ISA_IOSIZE") also seems something for 2K1000 now.

We need some detailed analysis of the issue and maybe some research on the ACPI specification.

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@elysia-best elysia-best Jan 16, 2026

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Right, a fast search for ISA_IOSIZE shows that this marco was introduced in initial commits for LoongArch support at torvalds@7153c3c

It didn't explain why this marco should be 16K rather than 64K. Additionally, ISA_IOSIZE is also used in loongnix's patch for this issue. I agree that this issue needs more analysis :)

pr_warn("Failed to reserve legacy IO in Logic PIO\n");
acpi_free_fwnode_static(fwnode);
}
}

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