From f63019861cd1192e546397b13f926876a93450fd Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <luto@kernel.org>
Date: Tue, 29 Dec 2015 22:53:51 -0800
Subject: [PATCH] platform/x86: wmi: Add an interface for subdrivers to access sibling devices
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Git-commit: f63019861cd1192e546397b13f926876a93450fd
Patch-mainline: v4.13-rc1
References: FATE#325842

Some subdrivers need to access sibling devices. This gives them a
clean way to do so.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/platform/x86/wmi.c |   17 +++++++++++++++++
 include/linux/wmi.h        |    4 ++++
 2 files changed, 21 insertions(+)

--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -344,6 +344,23 @@ union acpi_object *wmidev_block_query(st
 }
 EXPORT_SYMBOL_GPL(wmidev_block_query);
 
+struct wmi_device *wmidev_get_other_guid(struct wmi_device *wdev,
+					 const char *guid_string)
+{
+	struct wmi_block *this_wb = container_of(wdev, struct wmi_block, dev);
+	struct wmi_block *other_wb;
+
+	if (!find_guid(guid_string, &other_wb))
+		return NULL;
+
+	if (other_wb->acpi_device != this_wb->acpi_device)
+		return NULL;
+
+	get_device(&other_wb->dev.dev);
+	return &other_wb->dev;
+}
+EXPORT_SYMBOL_GPL(wmidev_get_other_guid);
+
 /**
  * wmi_set_block - Write to a WMI block
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
--- a/include/linux/wmi.h
+++ b/include/linux/wmi.h
@@ -33,6 +33,10 @@ struct wmi_device {
 extern union acpi_object *wmidev_block_query(struct wmi_device *wdev,
 					     u8 instance);
 
+/* Gets another device on the same bus.  Caller must put_device the result. */
+extern struct wmi_device *wmidev_get_other_guid(struct wmi_device *wdev,
+						const char *guid_string);
+
 struct wmi_device_id {
 	const char *guid_string;
 };