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author | Hans de Goede <hdegoede@redhat.com> | 2017-04-19 14:02:08 +0200 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2017-04-19 22:53:34 +0200 |
commit | 8661423eea1a1b58417014716e3f1ba286072379 (patch) | |
tree | 686462c9b7444bbc6ae2eb338901deb356c2c98b /drivers | |
parent | 4f7d029b9bf009fbee76bb10c0c4351a1870d2f3 (diff) | |
download | linux-8661423eea1a1b58417014716e3f1ba286072379.tar.bz2 |
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>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/acpi/utils.c | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c index 22c09952e177..27d0dcfcf47d 100644 --- a/drivers/acpi/utils.c +++ b/drivers/acpi/utils.c @@ -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. |