On Thursday, March 16, 2017 05:17:35 PM Hans de Goede wrote:
> acpi_dev_found just iterates over all acpi-ids and sees if one matches.
> This means that it will return true for devices which are in the dsdt
> but disabled (their _STA method returns 0).
>
> For some drivers it is useful to be able to check if a certain hid
> is not only present in the namespace, but also actually present as in
> acpi_device_is_present() will return true for the device. For example
> because if a certain device is present then the driver will want to use
> an extcon or IIO adc channel provided by that device.
>
> This commit adds a new acpi_dev_present helper which drivers can use
> to this end.
>
> Arguably acpi_dev_present is what acpi_dev_found should have been, but
> there are too many users to just change acpi_dev_found without the risk
> of breaking something.
>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Andy, Mika, any concerns about this patch, please?
> ---
> drivers/acpi/utils.c | 34 ++++++++++++++++++++++++++++++++++
> include/acpi/acpi_bus.h | 1 +
> include/linux/acpi.h | 5 +++++
> 3 files changed, 40 insertions(+)
>
> diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
> index 22c0995..40f8953 100644
> --- a/drivers/acpi/utils.c
> +++ b/drivers/acpi/utils.c
> @@ -736,6 +736,40 @@ bool acpi_dev_found(const char *hid)
> }
> EXPORT_SYMBOL(acpi_dev_found);
>
> +static acpi_status acpi_dev_present_cb(acpi_handle ah, u32 level, void *ctx,
> + void **retval)
> +{
> + /*
> + * acpi_get_devices() does all the work for us, if we get called
> + * a device with a matching hid has been found and its _STA indicates
> + * it is present.
> + */
> + *(bool *)ctx = true;
> + return AE_CTRL_TERMINATE;
> +}
> +
> +/**
> + * acpi_dev_present - Detect that a given ACPI device is present
> + * @hid: Hardware ID of the device.
> + *
> + * Return %true if the device was present at the moment of invocation.
> + * Note that if the device is pluggable, it may since have disappeared.
> + *
> + * Note that unlike acpi_dev_found() this function checks the status
> + * of the device so for devices which are present in the dsdt, but
> + * which are disabled (their _STA callback returns 0) this function
> + * will return false.
> + */
> +bool acpi_dev_present(const char *hid)
> +{
> + bool present = false;
> +
> + acpi_get_devices(hid, acpi_dev_present_cb, &present, NULL);
> +
> + return present;
> +}
> +EXPORT_SYMBOL(acpi_dev_present);
> +
> /*
> * acpi_backlight= handling, this is done here rather then in video_detect.c
> * because __setup cannot be used in modules.
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index ef0ae8a..29f6b5f 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -88,6 +88,7 @@ acpi_evaluate_dsm_typed(acpi_handle handle, const u8 *uuid, u64 rev, u64 func,
> }
>
> bool acpi_dev_found(const char *hid);
> +bool acpi_dev_present(const char *hid);
>
> #ifdef CONFIG_ACPI
>
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 673acda..059ffdc 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -614,6 +614,11 @@ static inline bool acpi_dev_found(const char *hid)
> return false;
> }
>
> +static inline bool acpi_dev_present(const char *hid)
> +{
> + return false;
> +}
> +
> static inline bool is_acpi_node(struct fwnode_handle *fwnode)
> {
> return false;
>
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