On Mon, 06 Feb 2023 13:50:42 -0700
Dave Jiang <dave.jiang@xxxxxxxxx> wrote:
> Provide a helper to find the ACPI0017 device in order to issue the _DSM.
> The helper will take the 'struct device' from a cxl_port and iterate until
> the root device is reached. The ACPI handle will be returned from the root
> device.
>
> Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> ---
> drivers/cxl/core/acpi.c | 30 ++++++++++++++++++++++++++++++
> drivers/cxl/cxl.h | 1 +
> 2 files changed, 31 insertions(+)
>
> diff --git a/drivers/cxl/core/acpi.c b/drivers/cxl/core/acpi.c
> index 86dc6c9c1f24..05fcd4751619 100644
> --- a/drivers/cxl/core/acpi.c
> +++ b/drivers/cxl/core/acpi.c
> @@ -5,6 +5,7 @@
> #include <linux/kernel.h>
> #include <linux/acpi.h>
> #include <linux/pci.h>
> +#include <linux/platform_device.h>
> #include <asm/div64.h>
> #include "cxlpci.h"
> #include "cxl.h"
> @@ -13,6 +14,35 @@ const guid_t acpi_cxl_qtg_id_guid =
> GUID_INIT(0xF365F9A6, 0xA7DE, 0x4071,
> 0xA6, 0x6A, 0xB4, 0x0C, 0x0B, 0x4F, 0x8E, 0x52);
>
> +/**
> + * cxl_acpi_get_root_acpi_handle - get the ACPI handle of the CXL root device
> + * @dev: 'struct device' to start searching from. Should be from cxl_port->dev.
> + * Looks for the ACPI0017 device and return the ACPI handle
> + **/
Inconsistent comment style.
> +acpi_handle cxl_acpi_get_rootdev_handle(struct device *dev)
> +{
> + struct device *itr = dev, *root_dev;
Not nice for readability to have an assignment in a list of definitions
all on the same line.
> + acpi_handle handle;
> +
> + if (!dev)
> + return ERR_PTR(-EINVAL);
> +
> + while (itr->parent) {
> + root_dev = itr;
> + itr = itr->parent;
> + }
> +
> + if (!dev_is_platform(root_dev))
> + return ERR_PTR(-ENODEV);
> +
> + handle = ACPI_HANDLE(root_dev);
> + if (!handle)
> + return ERR_PTR(-ENODEV);
> +
> + return handle;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_acpi_get_rootdev_handle, CXL);
> +
> /**
> * cxl_acpi_evaluate_qtg_dsm - Retrieve QTG ids via ACPI _DSM
> * @handle: ACPI handle
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index e70df07f9b4b..ac6ea550ab0a 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -733,6 +733,7 @@ struct qtg_dsm_output {
>
> struct qtg_dsm_output *cxl_acpi_evaluate_qtg_dsm(acpi_handle handle,
> struct qtg_dsm_input *input);
> +acpi_handle cxl_acpi_get_rootdev_handle(struct device *dev);
>
> /*
> * Unit test builds overrides this to __weak, find the 'strong' version
>
>
