[PATCH v3 12/14] acpi: Add acpi_dev_get_next_match_dev() and helper macro

[Daniel Scally]

To ensure we handle situations in which multiple sensors of the same
model (and therefore _HID) are present in a system, we need to be able
to iterate over devices matching a known _HID but unknown _UID and _HRV
 - add acpi_dev_get_next_match_dev() to accommodate that possibility and
change acpi_dev_get_first_match_dev() to simply call the new function
with a NULL starting point. Add an iterator macro for convenience.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Suggested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Daniel Scally <djrscally@xxxxxxxxx>
---
Changes in v3
	- prefixed referenced to the arguments with "@" in comment

 drivers/acpi/utils.c    | 30 ++++++++++++++++++++++++++----
 include/acpi/acpi_bus.h |  7 +++++++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index d5411a166685..ddca1550cce6 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -843,12 +843,13 @@ bool acpi_dev_present(const char *hid, const char *uid, s64 hrv)
 EXPORT_SYMBOL(acpi_dev_present);
 
 /**
- * acpi_dev_get_first_match_dev - Return the first match of ACPI device
+ * acpi_dev_get_next_match_dev - Return the next match of ACPI device
+ * @adev: Pointer to the previous acpi_device matching this @hid, @uid and @hrv
  * @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 the first match of ACPI device if a matching device was present
+ * Return the next match of ACPI device if another matching device was present
  * at the moment of invocation, or NULL otherwise.
  *
  * The caller is responsible to call put_device() on the returned device.
@@ -856,8 +857,9 @@ EXPORT_SYMBOL(acpi_dev_present);
  * See additional information in acpi_dev_present() as well.
  */
 struct acpi_device *
-acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv)
+acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const char *uid, s64 hrv)
 {
+	struct device *start = adev ? &adev->dev : NULL;
 	struct acpi_dev_match_info match = {};
 	struct device *dev;
 
@@ -865,9 +867,29 @@ acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv)
 	match.uid = uid;
 	match.hrv = hrv;
 
-	dev = bus_find_device(&acpi_bus_type, NULL, &match, acpi_dev_match_cb);
+	dev = bus_find_device(&acpi_bus_type, start, &match, acpi_dev_match_cb);
 	return dev ? to_acpi_device(dev) : NULL;
 }
+EXPORT_SYMBOL(acpi_dev_get_next_match_dev);
+
+/**
+ * acpi_dev_get_first_match_dev - Return the first match of ACPI device
+ * @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 the first match of ACPI device if a matching device was present
+ * at the moment of invocation, or NULL otherwise.
+ *
+ * The caller is responsible to call put_device() on the returned device.
+ *
+ * See additional information in acpi_dev_present() as well.
+ */
+struct acpi_device *
+acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv)
+{
+	return acpi_dev_get_next_match_dev(NULL, hid, uid, hrv);
+}
 EXPORT_SYMBOL(acpi_dev_get_first_match_dev);
 
 /*
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index a3abcc4b7d9f..0a028ba967d3 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -688,9 +688,16 @@ static inline bool acpi_device_can_poweroff(struct acpi_device *adev)
 
 bool acpi_dev_hid_uid_match(struct acpi_device *adev, const char *hid2, const char *uid2);
 
+struct acpi_device *
+acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const char *uid, s64 hrv);
 struct acpi_device *
 acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv);
 
+#define for_each_acpi_dev_match(adev, hid, uid, hrv)			\
+	for (adev = acpi_dev_get_first_match_dev(hid, uid, hrv);	\
+	     adev;							\
+	     adev = acpi_dev_get_next_match_dev(adev, hid, uid, hrv))
+
 static inline void acpi_dev_put(struct acpi_device *adev)
 {
 	put_device(&adev->dev);
-- 
2.25.1