[RFC PATCH 2/6] ACPI: Reference devices in ACPI Power Resource

[Lin Ming]

From: Zhang Rui <rui.zhang@xxxxxxxxx>

ACPI Power Resource can power on/off a couple of devices.
Introduce interfaces to register/unregister a device to/from
an ACPI Power Resource.

Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
---
 drivers/acpi/power.c    |  128 +++++++++++++++++++++++++++++++++++++++++++++++
 include/acpi/acpi_bus.h |    2 +
 2 files changed, 130 insertions(+), 0 deletions(-)

diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
index 0d681fb..a7e2305 100644
--- a/drivers/acpi/power.c
+++ b/drivers/acpi/power.c
@@ -84,10 +84,25 @@ struct acpi_power_resource {
 	u32 order;
 	unsigned int ref_count;
 	struct mutex resource_lock;
+	struct list_head devices; /* list for devices powered by this PR */
 };
 
 static struct list_head acpi_power_resource_list;
 
+/*
+ * When a power resource is turned on, all the devices are put to an uninitialized
+ * state although their ACPI states are still D0.
+ * To handle this, we need to keep a list of all devices powered by the power resource,
+ * and resume all of them.
+ * Currently, we only support this case:
+ * 1) multiple devices share the same power resoruce,
+ * 2) One device uses One Power Resource ONLY.
+ */
+struct acpi_powered_device {
+	struct list_head node;
+	struct device *dev;
+};
+
 /* --------------------------------------------------------------------------
                              Power Resource Management
    -------------------------------------------------------------------------- */
@@ -455,6 +470,118 @@ int acpi_disable_wakeup_device_power(struct acpi_device *dev)
                              Device Power Management
    -------------------------------------------------------------------------- */
 
+int acpi_power_resource_register_device(struct device *dev, acpi_handle handle)
+{
+	struct acpi_power_resource *resource;
+	struct acpi_device *acpi_dev, *res_dev;
+	acpi_handle res_handle = NULL;
+	struct acpi_powered_device *apd;
+	int i;
+	int ret;
+
+	if (!handle || !dev)
+		return -EINVAL;
+
+	ret = acpi_bus_get_device(handle, &acpi_dev);
+	if (ret)
+		goto no_power_resource;
+
+	if (!acpi_dev->power.flags.power_resources)
+		goto no_power_resource;
+
+	for (i = 0; i <= ACPI_STATE_D3; i++) {
+		struct acpi_device_power_state *ps = &acpi_dev->power.states[i];
+
+		if (!ps->flags.valid)
+			continue;
+
+		if (ps->resources.count > 1)
+			return 0;
+
+		if (!res_handle)
+			res_handle = ps->resources.handles[0];
+		else if (res_handle != ps->resources.handles[0])
+			return 0;
+	}
+
+	ret = acpi_bus_get_device(res_handle, &res_dev);
+	if (ret)
+		goto no_power_resource;
+
+	resource = res_dev->driver_data;
+	if (!resource)
+		goto no_power_resource;
+
+	apd = kzalloc(sizeof(struct acpi_powered_device), GFP_KERNEL);
+	if (!apd)
+		return -ENOMEM;
+
+	apd->dev = dev;
+	mutex_lock(&resource->resource_lock);
+	list_add_tail(&apd->node, &resource->devices);
+	mutex_unlock(&resource->resource_lock);
+	printk(KERN_INFO PREFIX "Device %s uses Power Resource %s\n", dev->kobj.name, acpi_device_name(res_dev));
+
+	return 0;
+
+no_power_resource:
+	printk(KERN_WARNING PREFIX "Invalid Power Resource to register!");
+	return -ENODEV;
+}
+
+void acpi_power_resource_unregister_device(struct device *dev, acpi_handle handle)
+{
+	struct acpi_power_resource *resource;
+	struct acpi_device *acpi_dev, *res_dev;
+	acpi_handle res_handle = NULL;
+	struct acpi_powered_device *apd, *tmp;
+	int i;
+	int ret;
+
+	if (!handle || !dev)
+		return;
+
+	ret = acpi_bus_get_device(handle, &acpi_dev);
+	if (ret)
+		return;
+
+	if (!acpi_dev->power.flags.power_resources)
+		return;
+
+	for (i = 0; i <= ACPI_STATE_D3; i++) {
+		struct acpi_device_power_state *ps = &acpi_dev->power.states[i];
+
+		if (!ps->flags.valid)
+			continue;
+
+		if (ps->resources.count > 1)
+			return;
+
+		res_handle = ps->resources.handles[0];
+		break;
+	}
+
+	if (!res_handle)
+		return;
+
+	ret = acpi_bus_get_device(res_handle, &res_dev);
+	if (ret)
+		return;
+
+	resource = res_dev->driver_data;
+	if (!resource)
+		return;
+
+	mutex_lock(&resource->resource_lock);
+	list_for_each_entry_safe(apd, tmp, &resource->devices, node) {
+		if (apd->dev == dev) {
+			list_del(&apd->node);
+			kfree(apd);
+		}
+	}
+	mutex_unlock(&resource->resource_lock);
+}
+
 int acpi_power_get_inferred_state(struct acpi_device *device, int *state)
 {
 	int result = 0;
@@ -550,6 +677,7 @@ static int acpi_power_add(struct acpi_device *device)
 
 	resource->device = device;
 	mutex_init(&resource->resource_lock);
+	INIT_LIST_HEAD(&resource->devices);
 	strcpy(resource->name, device->pnp.bus_id);
 	strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
 	strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 6cd5b64..32fb899 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -322,6 +322,8 @@ int acpi_bus_get_status(struct acpi_device *device);
 int acpi_bus_set_power(acpi_handle handle, int state);
 int acpi_bus_update_power(acpi_handle handle, int *state_p);
 bool acpi_bus_power_manageable(acpi_handle handle);
+int acpi_power_resource_register_device(struct device *dev, acpi_handle handle);
+void acpi_power_resource_unregister_device(struct device *dev, acpi_handle handle);
 bool acpi_bus_can_wakeup(acpi_handle handle);
 #ifdef CONFIG_ACPI_PROC_EVENT
 int acpi_bus_generate_proc_event(struct acpi_device *device, u8 type, int data);
-- 
1.7.2.5

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