From: Jean Pihet <j-pihet@xxxxxx>
Implement the per-device PM QoS constraints by creating a device
PM QoS API, which calls the PM QoS constraints management core code.
The per-device latency constraints data strctures are stored
in the device dev_pm_info struct.
The device PM code calls the init and destroy of the per-device constraints
data struct in order to support the dynamic insertion and removal of the
devices in the system.
To minimize the data usage by the per-device constraints, the data struct
is only allocated at the first call to dev_pm_qos_add_request.
The data is later free'd when the device is removed from the system.
Signed-off-by: Jean Pihet <j-pihet@xxxxxx>
---
drivers/base/power/Makefile | 4 +-
drivers/base/power/main.c | 3 +
drivers/base/power/qos.c | 262 +++++++++++++++++++++++++++++++++++++++++++
include/linux/pm.h | 9 ++
include/linux/pm_qos.h | 39 +++++++
5 files changed, 315 insertions(+), 2 deletions(-)
create mode 100644 drivers/base/power/qos.c
diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 3647e11..1a61f89 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -1,8 +1,8 @@
-obj-$(CONFIG_PM) += sysfs.o generic_ops.o
+obj-$(CONFIG_PM) += sysfs.o generic_ops.o qos.o
obj-$(CONFIG_PM_SLEEP) += main.o wakeup.o
obj-$(CONFIG_PM_RUNTIME) += runtime.o
obj-$(CONFIG_PM_TRACE_RTC) += trace.o
obj-$(CONFIG_PM_OPP) += opp.o
obj-$(CONFIG_HAVE_CLK) += clock_ops.o
-ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
\ No newline at end of file
+ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 06f09bf..f5c0e0e 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -22,6 +22,7 @@
#include <linux/mutex.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
+#include <linux/pm_qos.h>
#include <linux/resume-trace.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
@@ -97,6 +98,7 @@ void device_pm_add(struct device *dev)
dev_name(dev->parent));
list_add_tail(&dev->power.entry, &dpm_list);
mutex_unlock(&dpm_list_mtx);
+ dev_pm_qos_constraints_init(dev);
}
/**
@@ -107,6 +109,7 @@ void device_pm_remove(struct device *dev)
{
pr_debug("PM: Removing info for %s:%s\n",
dev->bus ? dev->bus->name : "No Bus", dev_name(dev));
+ dev_pm_qos_constraints_destroy(dev);
complete_all(&dev->power.completion);
mutex_lock(&dpm_list_mtx);
list_del_init(&dev->power.entry);
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
new file mode 100644
index 0000000..465e419
--- /dev/null
+++ b/drivers/base/power/qos.c
@@ -0,0 +1,262 @@
+/*
+ * This module exposes the interface to kernel space for specifying
+ * per-device PM QoS dependencies. It provides infrastructure for registration
+ * of:
+ *
+ * Dependents on a QoS value : register requests
+ * Watchers of QoS value : get notified when target QoS value changes
+ *
+ * This QoS design is best effort based. Dependents register their QoS needs.
+ * Watchers register to keep track of the current QoS needs of the system.
+ *
+ * Note about the per-device constraint data struct allocation:
+ * . The per-device constraints data struct ptr is tored into the device
+ * dev_pm_info.
+ * . To minimize the data usage by the per-device constraints, the data struct
+ * is only allocated at the first call to dev_pm_qos_add_request.
+ * . The data is later free'd when the device is removed from the system.
+ * . The constraints_state variable from dev_pm_info tracks the data struct
+ * allocation state:
+ * DEV_PM_QOS_NO_DEVICE: No device present or device removed, no data
+ * allocated,
+ * DEV_PM_QOS_DEVICE_PRESENT: Device present, data not allocated and will be
+ * allocated at the first call to dev_pm_qos_add_request,
+ * DEV_PM_QOS_ALLOCATED: Device present, data allocated. The per-device
+ * PM QoS constraints framework is operational and constraints can be
+ * added, updated or removed using the dev_pm_qos_* API.
+ */
+
+/*#define DEBUG*/
+
+#include <linux/pm_qos.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/device.h>
+#include <linux/string.h>
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+
+
+static void dev_pm_qos_constraints_allocate(struct device *dev);
+
+int dev_pm_qos_request_active(struct dev_pm_qos_request *req)
+{
+ return req->dev != 0;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_request_active);
+
+/**
+ * dev_pm_qos_add_request - inserts new qos request into the list
+ * @req: pointer to a preallocated handle
+ * @dev: target device for the constraint
+ * @value: defines the qos request
+ *
+ * This function inserts a new entry in the device constraints list of
+ * requested qos performance characteristics. It recomputes the aggregate
+ * QoS expectations of parameters and initializes the dev_pm_qos_request
+ * handle. Caller needs to save this handle for later use in updates and
+ * removal.
+ */
+void dev_pm_qos_add_request(struct dev_pm_qos_request *req, struct device *dev,
+ s32 value)
+{
+ if (!req) /*guard against callers passing in null */
+ return;
+
+ if (dev_pm_qos_request_active(req)) {
+ WARN(1, KERN_ERR "dev_pm_qos_add_request() called for already "
+ "added request\n");
+ return;
+ }
+ req->dev = dev;
+
+ /* Allocate the constraints struct on the first call to add_request */
+ if (req->dev->power.constraints_state == DEV_PM_QOS_DEVICE_PRESENT)
+ dev_pm_qos_constraints_allocate(dev);
+
+ /* Silently return if the device has been removed */
+ if (req->dev->power.constraints_state != DEV_PM_QOS_ALLOCATED)
+ return;
+
+ pm_qos_update_target(dev->power.constraints,
+ &req->node, PM_QOS_ADD_REQ, value);
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
+
+/**
+ * dev_pm_qos_update_request - modifies an existing qos request
+ * @req : handle to list element holding a dev_pm_qos request to use
+ * @value: defines the qos request
+ *
+ * Updates an existing dev PM qos request along with updating the
+ * target value.
+ *
+ * Attempts are made to make this code callable on hot code paths.
+ */
+void dev_pm_qos_update_request(struct dev_pm_qos_request *req,
+ s32 new_value)
+{
+ if (!req) /*guard against callers passing in null */
+ return;
+
+ if (!dev_pm_qos_request_active(req)) {
+ WARN(1, KERN_ERR "dev_pm_qos_update_request() called for "
+ "unknown object\n");
+ return;
+ }
+
+ /* Silently return if the device has been removed */
+ if (req->dev->power.constraints_state != DEV_PM_QOS_ALLOCATED)
+ return;
+
+ if (new_value != req->node.prio)
+ pm_qos_update_target(
+ req->dev->power.constraints,
+ &req->node, PM_QOS_UPDATE_REQ, new_value);
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
+
+/**
+ * dev_pm_qos_remove_request - modifies an existing qos request
+ * @req: handle to request list element
+ *
+ * Will remove pm qos request from the list of constraints and
+ * recompute the current target value. Call this on slow code paths.
+ */
+void dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
+{
+ if (!req) /*guard against callers passing in null */
+ return;
+
+ if (!dev_pm_qos_request_active(req)) {
+ WARN(1, KERN_ERR "dev_pm_qos_remove_request() called for "
+ "unknown object\n");
+ return;
+ }
+
+ /* Silently return if the device has been removed */
+ if (req->dev->power.constraints_state != DEV_PM_QOS_ALLOCATED)
+ return;
+
+ pm_qos_update_target(req->dev->power.constraints,
+ &req->node, PM_QOS_REMOVE_REQ,
+ PM_QOS_DEFAULT_VALUE);
+ memset(req, 0, sizeof(*req));
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
+
+/**
+ * dev_pm_qos_add_notifier - sets notification entry for changes to target value
+ * of per-device PM QoS constraints
+ *
+ * @dev: target device for the constraint
+ * @notifier: notifier block managed by caller.
+ *
+ * Will register the notifier into a notification chain that gets called
+ * upon changes to the target value for the device.
+ */
+int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
+{
+ int retval = 0;
+
+ /* Silently return if the device has been removed */
+ if (dev->power.constraints_state != DEV_PM_QOS_ALLOCATED)
+ return retval;
+
+ retval = blocking_notifier_chain_register(
+ dev->power.constraints->notifiers,
+ notifier);
+
+ return retval;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);
+
+/**
+ * dev_pm_qos_remove_notifier - deletes notification for changes to target value
+ * of per-device PM QoS constraints
+ *
+ * @dev: target device for the constraint
+ * @notifier: notifier block to be removed.
+ *
+ * Will remove the notifier from the notification chain that gets called
+ * upon changes to the target value.
+ */
+int dev_pm_qos_remove_notifier(struct device *dev,
+ struct notifier_block *notifier)
+{
+ int retval = 0;
+
+ /* Silently return if the device has been removed */
+ if (dev->power.constraints_state != DEV_PM_QOS_ALLOCATED)
+ return retval;
+
+ retval = blocking_notifier_chain_unregister(
+ dev->power.constraints->notifiers,
+ notifier);
+
+ return retval;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
+
+/* Called at the first call to add_request, for constraint data allocation */
+static void dev_pm_qos_constraints_allocate(struct device *dev)
+{
+ struct pm_qos_constraints *c;
+ struct blocking_notifier_head *n;
+
+ c = kzalloc(sizeof(*c), GFP_KERNEL);
+ if (!c)
+ return;
+
+ n = kzalloc(sizeof(*n), GFP_KERNEL);
+ if (!n) {
+ kfree(c);
+ return;
+ }
+ BLOCKING_INIT_NOTIFIER_HEAD(n);
+
+ dev->power.constraints = c;
+ plist_head_init(&dev->power.constraints->list, &dev->power.lock);
+ dev->power.constraints->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
+ dev->power.constraints->default_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
+ dev->power.constraints->type = PM_QOS_MIN;
+ dev->power.constraints->notifiers = n;
+ dev->power.constraints_state = DEV_PM_QOS_ALLOCATED;
+}
+
+/* Called from the device PM subsystem at device insertion */
+void dev_pm_qos_constraints_init(struct device *dev)
+{
+ dev->power.constraints_state = DEV_PM_QOS_DEVICE_PRESENT;
+}
+
+/* Called from the device PM subsystem at device removal */
+void dev_pm_qos_constraints_destroy(struct device *dev)
+{
+ struct dev_pm_qos_request *req, *tmp;
+ enum dev_pm_qos_state constraints_state = dev->power.constraints_state;
+
+ dev->power.constraints_state = DEV_PM_QOS_NO_DEVICE;
+ if (constraints_state == DEV_PM_QOS_ALLOCATED) {
+ /* Flush the constraints list for the device */
+ plist_for_each_entry_safe(req, tmp,
+ &dev->power.constraints->list,
+ node)
+ /*
+ * Update constraints list and call the per-device
+ * callbacks if needed
+ */
+ pm_qos_update_target(req->dev->power.constraints,
+ &req->node, PM_QOS_REMOVE_REQ,
+ PM_QOS_DEFAULT_VALUE);
+
+ kfree(dev->power.constraints->notifiers);
+ kfree(dev->power.constraints);
+ dev->power.constraints = NULL;
+ }
+}
+
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 411e4f4..aa6dc53 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -421,6 +421,13 @@ enum rpm_request {
struct wakeup_source;
+/* Per-device PM QoS constraints data struct state */
+enum dev_pm_qos_state {
+ DEV_PM_QOS_NO_DEVICE, /* No device present */
+ DEV_PM_QOS_DEVICE_PRESENT, /* Device present, data not allocated */
+ DEV_PM_QOS_ALLOCATED, /* Device present, data allocated */
+};
+
struct dev_pm_info {
pm_message_t power_state;
unsigned int can_wakeup:1;
@@ -463,6 +470,8 @@ struct dev_pm_info {
unsigned long accounting_timestamp;
void *subsys_data; /* Owned by the subsystem. */
#endif
+ struct pm_qos_constraints *constraints;
+ enum dev_pm_qos_state constraints_state;
};
extern void update_pm_runtime_accounting(struct device *dev);
diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index 84aa150..178eaa1 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -19,12 +19,18 @@
#define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
#define PM_QOS_NETWORK_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
#define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0
+#define PM_QOS_DEV_LAT_DEFAULT_VALUE 0
struct pm_qos_request {
struct plist_node node;
int pm_qos_class;
};
+struct dev_pm_qos_request {
+ struct plist_node node;
+ struct device *dev;
+};
+
enum pm_qos_type {
PM_QOS_UNITIALIZED,
PM_QOS_MAX, /* return the largest value */
@@ -64,6 +70,18 @@ int pm_qos_request(int pm_qos_class);
int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);
int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);
int pm_qos_request_active(struct pm_qos_request *req);
+
+int dev_pm_qos_request_active(struct dev_pm_qos_request *req);
+void dev_pm_qos_add_request(struct dev_pm_qos_request *req, struct device *dev,
+ s32 value);
+void dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value);
+void dev_pm_qos_remove_request(struct dev_pm_qos_request *req);
+int dev_pm_qos_add_notifier(struct device *dev,
+ struct notifier_block *notifier);
+int dev_pm_qos_remove_notifier(struct device *dev,
+ struct notifier_block *notifier);
+void dev_pm_qos_constraints_init(struct device *dev);
+void dev_pm_qos_constraints_destroy(struct device *dev);
#else
static inline int pm_qos_update_target(struct pm_qos_constraints *c,
struct plist_node *node,
@@ -89,6 +107,27 @@ static inline int pm_qos_remove_notifier(int pm_qos_class,
{ return 0; }
static inline int pm_qos_request_active(struct pm_qos_request *req)
{ return 0; }
+
+static inline int dev_pm_qos_request_active(struct dev_pm_qos_request *req)
+ { return 0; }
+static inline void dev_pm_qos_add_request(struct dev_pm_qos_request *req,
+ struct device *dev, s32 value)
+ { return; }
+static inline void dev_pm_qos_update_request(struct dev_pm_qos_request *req,
+ s32 new_value)
+ { return; }
+static inline void dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
+ { return; }
+static inline int dev_pm_qos_add_notifier(struct device *dev,
+ struct notifier_block *notifier)
+ { return 0; }
+static inline int dev_pm_qos_remove_notifier(struct device *dev,
+ struct notifier_block *notifier)
+ { return 0; }
+static inline void dev_pm_qos_constraints_init(struct device *dev)
+ { return; }
+static inline void dev_pm_qos_constraints_destroy(struct device *dev)
+ { return; }
#endif
#endif
--
1.7.2.5
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