On Fri, 27 Mar 2020 13:11:10 +0100
Gerd Hoffmann <kra...@redhat.com> wrote:
> The _STA method dates back to the days where we had a static DSDT. The
> device is listed in the DSDT table unconditionally and the _STA method
> checks a bit in the isa bridge pci config space to figure whenever a
> given is isa device is present or not, then evaluates to 0x0f (present)
> or 0x00 (absent).
>
> These days the DSDT is generated by qemu anyway, so if a device is not
> present we can simply drop it from the DSDT instead.
>
> Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
> ---
> hw/i386/acpi-build-pc.c | 32 ++++++++------------------------
> 1 file changed, 8 insertions(+), 24 deletions(-)
>
> diff --git a/hw/i386/acpi-build-pc.c b/hw/i386/acpi-build-pc.c
> index 18ca2fd46961..97af5eac3d79 100644
> --- a/hw/i386/acpi-build-pc.c
> +++ b/hw/i386/acpi-build-pc.c
> @@ -1204,50 +1204,34 @@ static Aml *build_lpt_device_aml(void)
> return dev;
> }
>
> -static Aml *build_com_device_aml(uint8_t uid)
> +static void build_com_device_aml(Aml *scope, uint8_t uid)
> {
> Aml *dev;
> Aml *crs;
> - Aml *method;
> - Aml *if_ctx;
> - Aml *else_ctx;
> - Aml *zero = aml_int(0);
> - Aml *is_present = aml_local(0);
> - const char *enabled_field = "CAEN";
> uint8_t irq = 4;
> uint16_t io_port = 0x03F8;
>
> assert(uid == 1 || uid == 2);
> if (uid == 2) {
> - enabled_field = "CBEN";
> irq = 3;
> io_port = 0x02F8;
> }
> + if (!memory_region_present(get_system_io(), io_port)) {
^^^^^^
even though acpi_setup() is a part of board code, usually it's not recommended
to
use get_system_foo() outside of machine_init()
how about fishing out present serial ports from isa device in a helper
like acpi_get_misc_info(), and then generalize AML like
build_com_device_aml(Aml *scope, uint8_t uid, io_port, irq)
> + return;
> + }
>
> dev = aml_device("COM%d", uid);
> aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0501")));
> aml_append(dev, aml_name_decl("_UID", aml_int(uid)));
>
> - method = aml_method("_STA", 0, AML_NOTSERIALIZED);
> - aml_append(method, aml_store(aml_name("%s", enabled_field), is_present));
> - if_ctx = aml_if(aml_equal(is_present, zero));
> - {
> - aml_append(if_ctx, aml_return(aml_int(0x00)));
> - }
> - aml_append(method, if_ctx);
> - else_ctx = aml_else();
> - {
> - aml_append(else_ctx, aml_return(aml_int(0x0f)));
> - }
> - aml_append(method, else_ctx);
> - aml_append(dev, method);
> + aml_append(dev, aml_name_decl("_STA", aml_int(0xf)));
>
> crs = aml_resource_template();
> aml_append(crs, aml_io(AML_DECODE16, io_port, io_port, 0x00, 0x08));
> aml_append(crs, aml_irq_no_flags(irq));
> aml_append(dev, aml_name_decl("_CRS", crs));
>
> - return dev;
> + aml_append(scope, dev);
> }
>
> static void build_isa_devices_aml(Aml *table)
> @@ -1265,8 +1249,8 @@ static void build_isa_devices_aml(Aml *table)
> aml_append(scope, build_fdc_device_aml(fdc));
> }
> aml_append(scope, build_lpt_device_aml());
> - aml_append(scope, build_com_device_aml(1));
> - aml_append(scope, build_com_device_aml(2));
> + build_com_device_aml(scope, 1);
> + build_com_device_aml(scope, 2);
>
> if (ambiguous) {
> error_report("Multiple ISA busses, unable to define IPMI ACPI data");
