From bbadbc67de278123e28dd6f9ee7e88b6ada56ce4 Mon Sep 17 00:00:00 2001
From: Lan Tianyu <tianyu.lan@intel.com>
Date: Fri, 21 Mar 2014 16:42:12 +0800
Subject: [PATCH] ACPI: temporary dep solution for battery support

This is a dep workaround for battery support on Asus T100TA and the formal
dep solution is under developing. This patch is just for test and will
not be upstreamed.
---
 drivers/acpi/scan.c    | 64 +++++++++++++++++++++++++++++++++++++++++++++++---
 drivers/i2c/i2c-acpi.c |  1 +
 include/linux/acpi.h   |  1 +
 3 files changed, 63 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 7efe546..254afb7 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -36,6 +36,7 @@ bool acpi_force_hot_remove;
 
 static const char *dummy_hid = "device";
 
+static LIST_HEAD(acpi_bus_dep_device_list);
 static LIST_HEAD(acpi_bus_id_list);
 static DEFINE_MUTEX(acpi_scan_lock);
 static LIST_HEAD(acpi_scan_handlers_list);
@@ -43,6 +44,12 @@ DEFINE_MUTEX(acpi_device_lock);
 LIST_HEAD(acpi_wakeup_device_list);
 static DEFINE_MUTEX(acpi_hp_context_lock);
 
+
+struct acpi_dep_handle {
+	struct list_head node;
+	acpi_handle handle;
+};
+
 struct acpi_device_bus_id{
 	char bus_id[15];
 	unsigned int instance_no;
@@ -2027,10 +2034,22 @@ static void acpi_scan_init_hotplug(struct acpi_device *adev)
 	}
 }
 
+
+static int acpi_dep_device_check(acpi_handle handle)
+{
+	struct acpi_dep_handle *dep;
+
+	list_for_each_entry(dep, &acpi_bus_dep_device_list, node)
+		if (dep->handle == handle)
+			return -EEXIST;
+	return 0;
+}
+
 static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
 				      void *not_used, void **return_value)
 {
 	struct acpi_device *device = NULL;
+	struct acpi_dep_handle *dep = NULL;
 	int type;
 	unsigned long long sta;
 	int result;
@@ -2048,9 +2067,24 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
 		return AE_OK;
 	}
 
-	acpi_add_single_object(&device, handle, type, sta);
-	if (!device)
-		return AE_CTRL_DEPTH;
+	if (!acpi_dep_device_check(handle)
+	   && acpi_has_method(handle, "_BIX")
+	   && acpi_has_method(handle, "_DEP")) {
+		dep = kmalloc(sizeof(struct acpi_dep_handle), GFP_KERNEL);
+		if (!dep)
+			return AE_CTRL_DEPTH;
+		dep->handle = handle;
+		list_add_tail(&dep->node , &acpi_bus_dep_device_list);
+
+		acpi_handle_info(dep->handle,
+				"is added to dep device list.\n");
+
+		return AE_OK;
+	} else {
+		acpi_add_single_object(&device, handle, type, sta);
+		if (!device)
+			return AE_CTRL_DEPTH;
+	}
 
 	acpi_scan_init_hotplug(device);
 
@@ -2061,6 +2095,30 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
 	return AE_OK;
 }
 
+int acpi_walk_dep_device_list(void)
+{
+	struct acpi_dep_handle *dep, *tmp;
+	acpi_status status;
+	unsigned long long sta;
+
+	list_for_each_entry_safe(dep, tmp, &acpi_bus_dep_device_list, node) {
+		status = acpi_evaluate_integer(dep->handle, "_STA", NULL, &sta);
+
+		if (ACPI_FAILURE(status)) {
+			acpi_handle_warn(dep->handle,
+				"Status check failed (0x%x)\n", status);
+		} else if (sta & ACPI_STA_DEVICE_ENABLED) {
+			acpi_bus_scan(dep->handle);
+			acpi_handle_info(dep->handle,
+				"Device is readly\n");
+			list_del(&dep->node);
+			kfree(dep);
+		}
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_walk_dep_device_list);
+
 static int acpi_scan_attach_handler(struct acpi_device *device)
 {
 	struct acpi_hardware_id *hwid;
diff --git a/drivers/i2c/i2c-acpi.c b/drivers/i2c/i2c-acpi.c
index a0ae867..471490a 100644
--- a/drivers/i2c/i2c-acpi.c
+++ b/drivers/i2c/i2c-acpi.c
@@ -349,6 +349,7 @@ int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
 		return -ENOMEM;
 	}
 
+	acpi_walk_dep_device_list();
 	return 0;
 }
 
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 667204c..66ad0dd 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -115,6 +115,7 @@ int acpi_boot_init (void);
 void acpi_boot_table_init (void);
 int acpi_mps_check (void);
 int acpi_numa_init (void);
+int acpi_walk_dep_device_list(void);
 
 int acpi_table_init (void);
 int acpi_table_parse(char *id, acpi_tbl_table_handler handler);
-- 
1.8.3.1