Hi, On 09-04-17 10:16, Lukas Wunner wrote:
On Sat, Apr 08, 2017 at 11:48:27PM +0200, 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. 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. Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> Cc: Lukas Wunner <lukas@xxxxxxxxx> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- Changes in v2: -Switch to using bus_find_device() to avoid "Traversing the namespace over and over" -Add optional (may be NULL / -1) uid and hrv arguments, this will allow this new function to replace the custom code for this in drivers/firmware/efi/dev-path-parser.c as well as in sound/soc/intel/common/sst-match-acpi.c and will allow it to be used to implement blacklists to avoid loading the ACPI ac / battery driver on systems which have a PMIC / charger acpi device with a native driver which offers a better (often working vs not working) user experience -Dropped Mika's reviewd by as this is almost a total rewrite Changes in v3: -memset the entire acpi_dev_present_info struct, this fixes acpi_device_id.cls not getting cleared Changes in v4: -Use empty initializer to zero the acpi_dev_present_info struct --- drivers/acpi/utils.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++ include/acpi/acpi_bus.h | 1 + include/linux/acpi.h | 5 ++++ 3 files changed, 77 insertions(+) diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c index 22c0995..ecd86a9 100644 --- a/drivers/acpi/utils.c +++ b/drivers/acpi/utils.c @@ -736,6 +736,77 @@ 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; + int hrv; +};There's a (somewhat theoretical) issue on 32 bit arches with your choice of int for hrv: _HRV returns an "Integer (DWORD)" per the spec. That's 32 bit and clashes with your use of -1 to signify "don't care" if the arch uses 32 bit to represent an int. So you need to use a "signed long long" or "s64" here.
Switched to s64 for v5.
+ +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->uid && !adev->pnp.unique_id && + strcmp("0", 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 "0" for devices without a _UID, + * 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^ Minor nit: I think readability improves if you start a new sentence or insert a comma here. Sorry, just my grammar OCD.
Started a new sentence at "So for" for v5.
Otherwise, Reviewed-by: Lukas Wunner <lukas@xxxxxxxxx>
Thank you.
I'm clueless about ACPI battery or charging, so can't say anything about the remainder of the series. Note that the code in drivers/firmware/efi/dev-path-parser.c deliberately increments the refcount of the device found and returns a pointer to it, whereas acpi_dev_present() as introduced by this patch merely checks presence and returns a bool. So you won't be able to replace the code in dev-path-parser.c with acpi_dev_present(), but I think that's perfectly fine.
Ah, bummer, would have been nice to be able to re-use the code. Regards, Hans
Thanks, Lukas+ * 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, int 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 ? true : false; +} +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..64498d5 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, const char *uid, int hrv); #ifdef CONFIG_ACPI diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 9b05886..e5dd0f1 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -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, int hrv) +{ + return false; +} + static inline bool is_acpi_node(struct fwnode_handle *fwnode) { return false; -- 2.9.3
-- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
