On Sun, Aug 29, 2021 at 3:22 PM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>
> This updates the following:
>
> 1) The ASL code to follow latest ACPI requirements, i.e.
> - static buffer to be defined outside of the method
> - The _ADR and _HID shouldn't be together for the same device
>
> 2) EFI section relies on the additional kernel configuration option,
> i.e. CONFIG_EFI_CUSTOM_SSDT_OVERLAYS
>
> 3) Refer to ACPI machine language as AML (capitalized)
>
> 4) Miscellaneous amendments
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Applied, thanks!
> ---
> .../admin-guide/acpi/ssdt-overlays.rst | 49 ++++++++++---------
> 1 file changed, 25 insertions(+), 24 deletions(-)
>
> diff --git a/Documentation/admin-guide/acpi/ssdt-overlays.rst b/Documentation/admin-guide/acpi/ssdt-overlays.rst
> index 5d7e25988085..b5fbf54dca19 100644
> --- a/Documentation/admin-guide/acpi/ssdt-overlays.rst
> +++ b/Documentation/admin-guide/acpi/ssdt-overlays.rst
> @@ -30,22 +30,21 @@ following ASL code can be used::
> {
> Device (STAC)
> {
> - Name (_ADR, Zero)
> Name (_HID, "BMA222E")
> + Name (RBUF, ResourceTemplate ()
> + {
> + I2cSerialBus (0x0018, ControllerInitiated, 0x00061A80,
> + AddressingMode7Bit, "\\_SB.I2C6", 0x00,
> + ResourceConsumer, ,)
> + GpioInt (Edge, ActiveHigh, Exclusive, PullDown, 0x0000,
> + "\\_SB.GPO2", 0x00, ResourceConsumer, , )
> + { // Pin list
> + 0
> + }
> + })
>
> Method (_CRS, 0, Serialized)
> {
> - Name (RBUF, ResourceTemplate ()
> - {
> - I2cSerialBus (0x0018, ControllerInitiated, 0x00061A80,
> - AddressingMode7Bit, "\\_SB.I2C6", 0x00,
> - ResourceConsumer, ,)
> - GpioInt (Edge, ActiveHigh, Exclusive, PullDown, 0x0000,
> - "\\_SB.GPO2", 0x00, ResourceConsumer, , )
> - { // Pin list
> - 0
> - }
> - })
> Return (RBUF)
> }
> }
> @@ -75,7 +74,7 @@ This option allows loading of user defined SSDTs from initrd and it is useful
> when the system does not support EFI or when there is not enough EFI storage.
>
> It works in a similar way with initrd based ACPI tables override/upgrade: SSDT
> -aml code must be placed in the first, uncompressed, initrd under the
> +AML code must be placed in the first, uncompressed, initrd under the
> "kernel/firmware/acpi" path. Multiple files can be used and this will translate
> in loading multiple tables. Only SSDT and OEM tables are allowed. See
> initrd_table_override.txt for more details.
> @@ -103,12 +102,14 @@ This is the preferred method, when EFI is supported on the platform, because it
> allows a persistent, OS independent way of storing the user defined SSDTs. There
> is also work underway to implement EFI support for loading user defined SSDTs
> and using this method will make it easier to convert to the EFI loading
> -mechanism when that will arrive.
> +mechanism when that will arrive. To enable it, the
> +CONFIG_EFI_CUSTOM_SSDT_OVERLAYS shoyld be chosen to y.
>
> -In order to load SSDTs from an EFI variable the efivar_ssdt kernel command line
> -parameter can be used. The argument for the option is the variable name to
> -use. If there are multiple variables with the same name but with different
> -vendor GUIDs, all of them will be loaded.
> +In order to load SSDTs from an EFI variable the ``"efivar_ssdt=..."`` kernel
> +command line parameter can be used (the name has a limitation of 16 characters).
> +The argument for the option is the variable name to use. If there are multiple
> +variables with the same name but with different vendor GUIDs, all of them will
> +be loaded.
>
> In order to store the AML code in an EFI variable the efivarfs filesystem can be
> used. It is enabled and mounted by default in /sys/firmware/efi/efivars in all
> @@ -127,7 +128,7 @@ variable with the content from a given file::
>
> #!/bin/sh -e
>
> - while ! [ -z "$1" ]; do
> + while [ -n "$1" ]; do
> case "$1" in
> "-f") filename="$2"; shift;;
> "-g") guid="$2"; shift;;
> @@ -167,14 +168,14 @@ variable with the content from a given file::
> Loading ACPI SSDTs from configfs
> ================================
>
> -This option allows loading of user defined SSDTs from userspace via the configfs
> +This option allows loading of user defined SSDTs from user space via the configfs
> interface. The CONFIG_ACPI_CONFIGFS option must be select and configfs must be
> mounted. In the following examples, we assume that configfs has been mounted in
> -/config.
> +/sys/kernel/config.
>
> -New tables can be loading by creating new directories in /config/acpi/table/ and
> -writing the SSDT aml code in the aml attribute::
> +New tables can be loading by creating new directories in /sys/kernel/config/acpi/table
> +and writing the SSDT AML code in the aml attribute::
>
> - cd /config/acpi/table
> + cd /sys/kernel/config/acpi/table
> mkdir my_ssdt
> cat ~/ssdt.aml > my_ssdt/aml
> --
> 2.33.0
>
