PM QOS update

This patch changes the string based list management to a handle base
implementation to help with the hot path use of pm-qos, it also renames
much of the API to use "request" as opposed to "requirement" that was
used in the initial implementation.  I did this because request more
accurately represents what it actually does.

Also, I added a string based ABI for users wanting to use a string
interface.  So if the user writes 0xDDDDDDDD formatted hex it will be
accepted by the interface.  (someone asked me for it and I don't think
it hurts anything.)

This patch updates some documentation input I got from Randy.

Signed-off-by: markgross <mgross@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

14 files changed, 176 insertions, 171 deletions

diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt
index c40866e8b957..bfed898a03fc 100644
--- a/Documentation/power/pm_qos_interface.txt
+++ b/Documentation/power/pm_qos_interface.txt
@@ -18,44 +18,46 @@ and pm_qos_params.h.  This is done because having the available parameters
 being runtime configurable or changeable from a driver was seen as too easy to
 abuse.
 
-For each parameter a list of performance requirements is maintained along with
+For each parameter a list of performance requests is maintained along with
 an aggregated target value.  The aggregated target value is updated with
-changes to the requirement list or elements of the list.  Typically the
-aggregated target value is simply the max or min of the requirement values held
+changes to the request list or elements of the list.  Typically the
+aggregated target value is simply the max or min of the request values held
 in the parameter list elements.
 
 From kernel mode the use of this interface is simple:
-pm_qos_add_requirement(param_id, name, target_value):
-Will insert a named element in the list for that identified PM_QOS parameter
-with the target value.  Upon change to this list the new target is recomputed
-and any registered notifiers are called only if the target value is now
-different.
 
-pm_qos_update_requirement(param_id, name, new_target_value):
-Will search the list identified by the param_id for the named list element and
-then update its target value, calling the notification tree if the aggregated
-target is changed.  with that name is already registered.
+handle = pm_qos_add_request(param_class, target_value):
+Will insert an element into the list for that identified PM_QOS class with the
+target value.  Upon change to this list the new target is recomputed and any
+registered notifiers are called only if the target value is now different.
+Clients of pm_qos need to save the returned handle.
 
-pm_qos_remove_requirement(param_id, name):
-Will search the identified list for the named element and remove it, after
-removal it will update the aggregate target and call the notification tree if
-the target was changed as a result of removing the named requirement.
+void pm_qos_update_request(handle, new_target_value):
+Will update the list element pointed to by the handle with the new target value
+and recompute the new aggregated target, calling the notification tree if the
+target is changed.
+
+void pm_qos_remove_request(handle):
+Will remove the element.  After removal it will update the aggregate target and
+call the notification tree if the target was changed as a result of removing
+the request.
 
 
 From user mode:
-Only processes can register a pm_qos requirement.  To provide for automatic
-cleanup for process the interface requires the process to register its
-parameter requirements in the following way:
+Only processes can register a pm_qos request.  To provide for automatic
+cleanup of a process, the interface requires the process to register its
+parameter requests in the following way:
 
 To register the default pm_qos target for the specific parameter, the process
 must open one of /dev/[cpu_dma_latency, network_latency, network_throughput]
 
 As long as the device node is held open that process has a registered
-requirement on the parameter.  The name of the requirement is "process_<PID>"
-derived from the current->pid from within the open system call.
+request on the parameter.
 
-To change the requested target value the process needs to write a s32 value to
-the open device node.  This translates to a pm_qos_update_requirement call.
+To change the requested target value the process needs to write an s32 value to
+the open device node.  Alternatively the user mode program could write a hex
+string for the value using 10 char long format e.g. "0x12345678".  This
+translates to a pm_qos_update_request call.
 
 To remove the user mode request for a target value simply close the device
 node.
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 5939e7f7d8e9..c3817e1f32c7 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -698,7 +698,7 @@ static int acpi_processor_power_seq_show(struct seq_file *seq, void *offset)
                    "max_cstate:              C%d\n"
                    "maximum allowed latency: %d usec\n",
                    pr->power.state ? pr->power.state - pr->power.states : 0,
-                   max_cstate, pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY));
+                   max_cstate, pm_qos_request(PM_QOS_CPU_DMA_LATENCY));
 
         seq_puts(seq, "states:\n");
 
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index 1c1ceb4f218f..12c98900dcf8 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -67,7 +67,7 @@ static int ladder_select_state(struct cpuidle_device *dev)
         struct ladder_device *ldev = &__get_cpu_var(ladder_devices);
         struct ladder_device_state *last_state;
         int last_residency, last_idx = ldev->last_state_idx;
-        int latency_req = pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY);
+        int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
 
         /* Special case when user has set very strict latency requirement */
         if (unlikely(latency_req == 0)) {
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index f8e57c6303f2..b81ad9c731ae 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -182,7 +182,7 @@ static u64 div_round64(u64 dividend, u32 divisor)
 static int menu_select(struct cpuidle_device *dev)
 {
         struct menu_device *data = &__get_cpu_var(menu_devices);
-        int latency_req = pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY);
+        int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
         int i;
         int multiplier;
 
diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index dbf81788bb40..d5d55c6a373f 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -2524,12 +2524,12 @@ static void e1000_configure_rx(struct e1000_adapter *adapter)
                          * excessive C-state transition latencies result in
                          * dropped transactions.
                          */
-                        pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY,
-                                                  adapter->netdev->name, 55);
+                        pm_qos_update_request(
+                                adapter->netdev->pm_qos_req, 55);
                 } else {
-                        pm_qos_update_requirement(PM_QOS_CPU_DMA_LATENCY,
-                                                  adapter->netdev->name,
-                                                  PM_QOS_DEFAULT_VALUE);
+                        pm_qos_update_request(
+                                adapter->netdev->pm_qos_req,
+                                PM_QOS_DEFAULT_VALUE);
                 }
         }
 
@@ -2824,8 +2824,8 @@ int e1000e_up(struct e1000_adapter *adapter)
 
         /* DMA latency requirement to workaround early-receive/jumbo issue */
         if (adapter->flags & FLAG_HAS_ERT)
-                pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY,
-                                       adapter->netdev->name,
+                adapter->netdev->pm_qos_req =
+                        pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY,
                                        PM_QOS_DEFAULT_VALUE);
 
         /* hardware has been reset, we need to reload some things */
@@ -2887,9 +2887,11 @@ void e1000e_down(struct e1000_adapter *adapter)
         e1000_clean_tx_ring(adapter);
         e1000_clean_rx_ring(adapter);