Merge tag 'acpi-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI updates from Rafael Wysocki:
 "These rework the handling of ACPI device objects to use the driver
  core facilities for managing child ones instead of some questionable
  home-grown ways without the requisite locking and reference counting,
  clean up the EC driver, improve suspend-to-idle handling on x86, add
  some systems to the ACPI backlight quirk list, fix some assorted
  issues, clean up code and improve documentation.

  Specifics:

   - Use facilities provided by the driver core and some additional
     helpers to handle the children of a given ACPI device object in
     multiple places instead of using the children and node list heads
     in struct acpi_device which is error prone (Rafael Wysocki).

   - Fix ACPI-related device reference counting issue in the hisi_lpc
     bus driver (Yang Yingliang).

   - Drop the children and node list heads that are not needed any more
     from struct acpi_device (Rafael Wysocki).

   - Drop driver member from struct acpi_device (Uwe Kleine-König).

   - Drop redundant check from acpi_device_remove() (Uwe Kleine-König).

   - Prepare the CPPC library for handling backwards-compatible future
     _CPC return package formats gracefully (Rafael Wysocki).

   - Clean up the ACPI EC driver after previous changes in it (Hans de
     Goede).

   - Drop leftover acpi_processor_get_limit_info() declaration (Riwen
     Lu).

   - Split out thermal initialization from ACPI PSS (Riwen Lu).

   - Annotate more functions in the ACPI CPU idle driver to live in the
     cpuidle section (Guilherme G. Piccoli).

   - Fix _EINJ vs "special purpose" EFI memory regions (Dan Williams).

   - Implement a better fix to avoid spamming the console with old error
     logs (Tony Luck).

   - Fix typo in a comment in the APEI code (Xiang wangx).

   - Save NVS memory during transitions into S3 on Lenovo G40-45 (Manyi
     Li).

   - Add support for upcoming AMD uPEP device ID AMDI008 to the ACPI
     suspend-to-idle driver for x86 platforms (Shyam Sundar S K).

   - Clean up checks related to the ACPI_FADT_LOW_POWER_S0 platform flag
     in the LPIT table driver and the suspend-to-idle driver for x86
     platforms (Rafael Wysocki).

   - Print information messages regarding declared LPS0 idle support in
     the platform firmware (Rafael Wysocki).

   - Fix missing check in register_device_clock() in the ACPI driver for
     Intel SoCs (huhai).

   - Fix ACS setup in the VIOT table parser (Eric Auger).

   - Skip IRQ override on AMD Zen platforms where it's harmful
     (Chuanhong Guo).

   - Use native backlight on Dell Inspiron N4010 (Hans de Goede).

   - Use native backlight on some TongFang devices (Werner Sembach).

   - Drop X86 dependency from the ACPI backlight driver Kconfig (Riwen
     Lu).

   - Shorten the quirk list in the ACPI backlight driver by identifying
     Clevo by board_name only (Werner Sembach).

   - Remove useless NULL pointer checks from 2 ACPI PCI link management
     functions (Andrey Strachuk).

   - Fix obsolete example in the ACPI EINJ documentation (Qifu Zhang).

   - Update links and references to _DSD-related documents (Sudeep
     Holla)"

* tag 'acpi-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (46 commits)
  ACPI/PCI: Remove useless NULL pointer checks
  ACPI: CPPC: Do not prevent CPPC from working in the future
  ACPI: PM: x86: Print messages regarding LPS0 idle support
  ACPI: resource: skip IRQ override on AMD Zen platforms
  Documentation: ACPI: EINJ: Fix obsolete example
  ACPI: video: Use native backlight on Dell Inspiron N4010
  ACPI: PM: s2idle: Use LPS0 idle if ACPI_FADT_LOW_POWER_S0 is unset
  Revert "ACPI / PM: LPIT: Register sysfs attributes based on FADT"
  ACPI: video: Shortening quirk list by identifying Clevo by board_name only
  ACPI: video: Force backlight native for some TongFang devices
  ACPI: PM: s2idle: Add support for upcoming AMD uPEP HID AMDI008
  ACPI: VIOT: Fix ACS setup
  ACPI: bus: Drop unused list heads from struct acpi_device
  hisi_lpc: Use acpi_dev_for_each_child()
  bus: hisi_lpc: fix missing platform_device_put() in hisi_lpc_acpi_probe()
  ACPI: bus: Drop driver member of struct acpi_device
  ACPI: bus: Drop redundant check in acpi_device_remove()
  ACPI: APEI: Fix _EINJ vs EFI_MEMORY_SP
  ACPI: LPSS: Fix missing check in register_device_clock()
  ACPI: APEI: Better fix to avoid spamming the console with old error logs
  ...

1 files changed, 93 insertions, 40 deletions

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 8d769114a048..204fe94c7e45 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -77,12 +77,22 @@ static struct acpi_bus_type *acpi_get_bus_type(struct device *dev)
 #define FIND_CHILD_MIN_SCORE	1
 #define FIND_CHILD_MAX_SCORE	2
 
+static int match_any(struct acpi_device *adev, void *not_used)
+{
+	return 1;
+}
+
+static bool acpi_dev_has_children(struct acpi_device *adev)
+{
+	return acpi_dev_for_each_child(adev, match_any, NULL) > 0;
+}
+
 static int find_child_checks(struct acpi_device *adev, bool check_children)
 {
 	unsigned long long sta;
 	acpi_status status;
 
-	if (check_children && list_empty(&adev->children))
+	if (check_children && !acpi_dev_has_children(adev))
 		return -ENODEV;
 
 	status = acpi_evaluate_integer(adev->handle, "_STA", NULL, &sta);
@@ -105,54 +115,97 @@ static int find_child_checks(struct acpi_device *adev, bool check_children)
 	return FIND_CHILD_MAX_SCORE;
 }
 
-struct acpi_device *acpi_find_child_device(struct acpi_device *parent,
-					   u64 address, bool check_children)
-{
-	struct acpi_device *adev, *ret = NULL;
-	int ret_score = 0;
-
-	if (!parent)
-		return NULL;
+struct find_child_walk_data {
+	struct acpi_device *adev;
+	u64 address;
+	int score;
+	bool check_sta;
+	bool check_children;
+};
 
-	list_for_each_entry(adev, &parent->children, node) {
-		acpi_bus_address addr = acpi_device_adr(adev);
-		int score;
+static int check_one_child(struct acpi_device *adev, void *data)
+{
+	struct find_child_walk_data *wd = data;
+	int score;
 
-		if (!adev->pnp.type.bus_address || addr != address)
-			continue;
+	if (!adev->pnp.type.bus_address || acpi_device_adr(adev) != wd->address)
+		return 0;
 
-		if (!ret) {
-			/* This is the first matching object.  Save it. */
-			ret = adev;
-			continue;
-		}
+	if (!wd->adev) {
 		/*
-		 * There is more than one matching device object with the same
-		 * _ADR value.  That really is unexpected, so we are kind of
-		 * beyond the scope of the spec here.  We have to choose which
-		 * one to return, though.
-		 *
-		 * First, check if the previously found object is good enough
-		 * and return it if so.  Second, do the same for the object that
-		 * we've just found.
+		 * This is the first matching object, so save it.  If it is not
+		 * necessary to look for any other matching objects, stop the
+		 * search.
 		 */
-		if (!ret_score) {
-			ret_score = find_child_checks(ret, check_children);
-			if (ret_score == FIND_CHILD_MAX_SCORE)
-				return ret;
-		}
-		score = find_child_checks(adev, check_children);
-		if (score == FIND_CHILD_MAX_SCORE) {
-			return adev;
-		} else if (score > ret_score) {
-			ret = adev;
-			ret_score = score;
-		}
+		wd->adev = adev;
+		return !(wd->check_sta || wd->check_children);
 	}
-	return ret;
+
+	/*
+	 * There is more than one matching device object with the same _ADR
+	 * value.  That really is unexpected, so we are kind of beyond the scope
+	 * of the spec here.  We have to choose which one to return, though.
+	 *
+	 * First, get the score for the previously found object and terminate
+	 * the walk if it is maximum.
+	*/
+	if (!wd->score) {
+		score = find_child_checks(wd->adev, wd->check_children);
+		if (score == FIND_CHILD_MAX_SCORE)
+			return 1;
+
+		wd->score = score;
+	}
+	/*
+	 * Second, if the object that has just been found has a better score,
+	 * replace the previously found one with it and terminate the walk if
+	 * the new score is maximum.
+	 */
+	score = find_child_checks(adev, wd->check_children);
+	if (score > wd->score) {
+		wd->adev = adev;
+		if (score == FIND_CHILD_MAX_SCORE)
+			return 1;
+
+		wd->score = score;
+	}
+
+	/* Continue, because there may be better matches. */
+	return 0;
+}
+
+static struct acpi_device *acpi_find_child(struct acpi_device *parent,
+					   u64 address, bool check_children,
+					   bool check_sta)
+{
+	struct find_child_walk_data wd = {
+		.address = address,
+		.check_children = check_children,
+		.check_sta = check_sta,
+		.adev = NULL,
+		.score = 0,
+	};
+
+	if (parent)
+		acpi_dev_for_each_child(parent, check_one_child, &wd);
+
+	return wd.adev;
+}
+
+struct acpi_device *acpi_find_child_device(struct acpi_device *parent,
+					   u64 address, bool check_children)
+{
+	return acpi_find_child(parent, address, check_children, true);
 }
 EXPORT_SYMBOL_GPL(acpi_find_child_device);
 
+struct acpi_device *acpi_find_child_by_adr(struct acpi_device *adev,
+					   acpi_bus_address adr)
+{
+	return acpi_find_child(adev, adr, false, false);
+}
+EXPORT_SYMBOL_GPL(acpi_find_child_by_adr);
+
 static void acpi_physnode_link_name(char *buf, unsigned int node_id)
 {
 	if (node_id > 0)