ACPI / utils: Add new acpi_dev_present helper

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.

Like acpi_dev_found, acpi_dev_present take a HID as argument, but
it also has 2 extra optional arguments to only check for an ACPI
device with a specific UID and/or HRV value. This makes it more
generic and allows it to replace custom code doing similar checks
in several places.

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@redhat.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Hans de Goede 2017-04-19 14:02:08 +02:00 committed by Rafael J. Wysocki
parent 4f7d029b9b
commit 8661423eea
3 changed files with 72 additions and 0 deletions

View File

@ -736,6 +736,72 @@ bool acpi_dev_found(const char *hid)
}
EXPORT_SYMBOL(acpi_dev_found);
struct acpi_dev_present_info {
struct acpi_device_id hid[2];
const char *uid;
s64 hrv;
};
static int acpi_dev_present_cb(struct device *dev, void *data)
{
struct acpi_device *adev = to_acpi_device(dev);
struct acpi_dev_present_info *match = data;
unsigned long long hrv;
acpi_status status;
if (acpi_match_device_ids(adev, match->hid))
return 0;
if (match->uid && (!adev->pnp.unique_id ||
strcmp(adev->pnp.unique_id, match->uid)))
return 0;
if (match->hrv == -1)
return 1;
status = acpi_evaluate_integer(adev->handle, "_HRV", NULL, &hrv);
if (ACPI_FAILURE(status))
return 0;
return hrv == match->hrv;
}
/**
* acpi_dev_present - Detect that a given ACPI device is present
* @hid: Hardware ID of the device.
* @uid: Unique ID of the device, pass NULL to not check _UID
* @hrv: Hardware Revision of the device, pass -1 to not check _HRV
*
* Return %true if a matching 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.
*
* For this function to work, acpi_bus_scan() must have been executed
* which happens in the subsys_initcall() subsection. Hence, do not
* call from a subsys_initcall() or earlier (use acpi_get_devices()
* instead). Calling from module_init() is fine (which is synonymous
* with device_initcall()).
*/
bool acpi_dev_present(const char *hid, const char *uid, s64 hrv)
{
struct acpi_dev_present_info match = {};
struct device *dev;
strlcpy(match.hid[0].id, hid, sizeof(match.hid[0].id));
match.uid = uid;
match.hrv = hrv;
dev = bus_find_device(&acpi_bus_type, NULL, &match,
acpi_dev_present_cb);
return !!dev;
}
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.

View File

@ -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, const char *uid, s64 hrv);
#ifdef CONFIG_ACPI

View File

@ -611,6 +611,11 @@ static inline bool acpi_dev_found(const char *hid)
return false;
}
static inline bool acpi_dev_present(const char *hid, const char *uid, s64 hrv)
{
return false;
}
static inline bool is_acpi_node(struct fwnode_handle *fwnode)
{
return false;