Re: [PATCH 2/5] MIPS: Loongson64: Process ISA Node in DeviceTree

[Huacai Chen <chenhc@lemote.com>]

Hi, Jiaxun,

On Mon, Jul 20, 2020 at 6:20 PM Jiaxun Yang <jiaxun.yang@flygoat.com> wrote:
>
>
>
> 在 2020/7/20 下午6:01, Huacai Chen 写道:
> > Hi, Jiaxun,
> >
> > On Mon, Jul 20, 2020 at 3:44 PM Jiaxun Yang <jiaxun.yang@flygoat.com> wrote:
> >> Previously, we're hardcoding resserved ISA I/O Space in code, now
> >> we're processing reverved I/O via DeviceTree directly. Using the ranges
> >> property to determine the size and address of reserved I/O space.
> > Maybe it is better to reserve a default legacy io range if there is no
> > "isa" node in the .dts file?
>
> As currently all dts is built-in in Kernel, I don't think it's necessary.
>
> Also the only ISA driver remaining that can't be probed by dts is i8042.
> We can convert it to DeviceTree based, and then we'll always be safe.
>
If you don't reserve a default legacy io range, then I should define
an "isa" node for KVM guests even if the VM doesn't have i8042 and
i8259. Because some pci devices still have legacy i/o ports, such as
qxl. I have tested your patches and found that KVM guests with qxl
cannot work without an "isa" node.

Huacai
> Thanks.
>
> - Jiaxun
>
> >
> > Huacai
> >> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> >> ---
> >>   arch/mips/loongson64/init.c | 85 ++++++++++++++++++++++++++-----------
> >>   1 file changed, 60 insertions(+), 25 deletions(-)
> >>
> >> diff --git a/arch/mips/loongson64/init.c b/arch/mips/loongson64/init.c
> >> index 59ddadace83f..028d7b324ec2 100644
> >> --- a/arch/mips/loongson64/init.c
> >> +++ b/arch/mips/loongson64/init.c
> >> @@ -7,6 +7,8 @@
> >>   #include <linux/irqchip.h>
> >>   #include <linux/logic_pio.h>
> >>   #include <linux/memblock.h>
> >> +#include <linux/of.h>
> >> +#include <linux/of_address.h>
> >>   #include <asm/bootinfo.h>
> >>   #include <asm/traps.h>
> >>   #include <asm/smp-ops.h>
> >> @@ -63,41 +65,74 @@ void __init prom_free_prom_memory(void)
> >>   {
> >>   }
> >>
> >> -static __init void reserve_pio_range(void)
> >> +static int __init add_legacy_isa_io(struct fwnode_handle *fwnode, phys_addr_t addr,
> >> +                            resource_size_t    size)
> >>   {
> >> +       int ret = 0;
> >>          struct logic_pio_hwaddr *range;
> >> +       unsigned long vaddr;
> >>
> >>          range = kzalloc(sizeof(*range), GFP_ATOMIC);
> >>          if (!range)
> >> -               return;
> >> +               return -ENOMEM;
> >>
> >> -       range->fwnode = &of_root->fwnode;
> >> -       range->size = MMIO_LOWER_RESERVED;
> >> -       range->hw_start = LOONGSON_PCIIO_BASE;
> >> +       range->fwnode = fwnode;
> >> +       range->size = size;
> >> +       range->hw_start = addr;
> >>          range->flags = LOGIC_PIO_CPU_MMIO;
> >>
> >> -       if (logic_pio_register_range(range)) {
> >> -               pr_err("Failed to reserve PIO range for legacy ISA\n");
> >> -               goto free_range;
> >> +       ret = logic_pio_register_range(range);
> >> +       if (ret) {
> >> +               kfree(range);
> >> +               return ret;
> >> +       }
> >> +
> >> +       /* Legacy ISA must placed at the start of PCI_IOBASE */
> >> +       if (range->io_start != 0) {
> >> +               logic_pio_unregister_range(range);
> >> +               kfree(range);
> >> +               return -EINVAL;
> >>          }
> >>
> >> -       if (WARN(range->io_start != 0,
> >> -                       "Reserved PIO range does not start from 0\n"))
> >> -               goto unregister;
> >> -
> >> -       /*
> >> -        * i8259 would access I/O space, so mapping must be done here.
> >> -        * Please remove it when all drivers can be managed by logic_pio.
> >> -        */
> >> -       ioremap_page_range(PCI_IOBASE, PCI_IOBASE + MMIO_LOWER_RESERVED,
> >> -                               LOONGSON_PCIIO_BASE,
> >> -                               pgprot_device(PAGE_KERNEL));
> >> -
> >> -       return;
> >> -unregister:
> >> -       logic_pio_unregister_range(range);
> >> -free_range:
> >> -       kfree(range);
> >> +       vaddr = PCI_IOBASE + range->io_start;
> >> +
> >> +       ioremap_page_range(vaddr, vaddr + size, addr, pgprot_device(PAGE_KERNEL));
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +static __init void reserve_pio_range(void)
> >> +{
> >> +       struct device_node *np;
> >> +
> >> +       for_each_node_by_name(np, "isa") {
> >> +               struct of_pci_range range;
> >> +               struct of_pci_range_parser parser;
> >> +
> >> +               pr_info("ISA Bridge: %pOF\n", np);
> >> +
> >> +               if (of_pci_range_parser_init(&parser, np)) {
> >> +                       pr_info("Failed to parse resources.\n");
> >> +                       break;
> >> +               }
> >> +
> >> +               for_each_of_pci_range(&parser, &range) {
> >> +                       switch (range.flags & IORESOURCE_TYPE_BITS) {
> >> +                       case IORESOURCE_IO:
> >> +                               pr_info(" IO 0x%016llx..0x%016llx\n",
> >> +                                       range.cpu_addr,
> >> +                                       range.cpu_addr + range.size - 1);
> >> +                               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\n",
> >> +                                       range.cpu_addr,
> >> +                                       range.cpu_addr + range.size - 1);
> >> +                               break;
> >> +                       }
> >> +               }
> >> +       }
> >>   }
> >>
> >>   void __init arch_init_irq(void)
> >> --
> >> 2.28.0.rc1
> >>