clockevents: Manage device's state separately for the core

'enum clock_event_mode' is used for two purposes today:

 - to pass mode to the driver of clockevent device::set_mode().

 - for managing state of the device for clockevents core.

For supporting new modes/states we have moved away from the
legacy set_mode() callback to new per-mode/state callbacks. New
modes/states shouldn't be exposed to the legacy (now OBSOLOTE)
callbacks and so we shouldn't add new states to 'enum
clock_event_mode'.

Lets have separate enums for the two use cases mentioned above.
Keep using the earlier enum for legacy set_mode() callback and
mark it OBSOLETE. And add another enum to clearly specify the
possible states of a clockevent device.

This also renames the newly added per-mode callbacks to reflect
state changes.

We haven't got rid of 'mode' member of 'struct
clock_event_device' as it is used by some of the clockevent
drivers and it would automatically die down once we migrate
those drivers to the new interface. It ('mode') is only updated
now for the drivers using the legacy interface.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: linaro-networking@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/b6b0143a8a57bd58352ad35e08c25424c879c0cb.1425037853.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 31 insertions, 13 deletions

diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index a41749543d48..e20232c3320a 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -32,15 +32,31 @@ enum clock_event_nofitiers {
 struct clock_event_device;
 struct module;
 
-/* Clock event mode commands */
+/* Clock event mode commands for legacy ->set_mode(): OBSOLETE */
 enum clock_event_mode {
 	CLOCK_EVT_MODE_UNUSED = 0,
 	CLOCK_EVT_MODE_SHUTDOWN,
 	CLOCK_EVT_MODE_PERIODIC,
 	CLOCK_EVT_MODE_ONESHOT,
 	CLOCK_EVT_MODE_RESUME,
+};
 
-	/* Legacy ->set_mode() callback doesn't support below modes */
+/*
+ * Possible states of a clock event device.
+ *
+ * DETACHED:	Device is not used by clockevents core. Initial state or can be
+ *		reached from SHUTDOWN.
+ * SHUTDOWN:	Device is powered-off. Can be reached from PERIODIC or ONESHOT.
+ * PERIODIC:	Device is programmed to generate events periodically. Can be
+ *		reached from DETACHED or SHUTDOWN.
+ * ONESHOT:	Device is programmed to generate event only once. Can be reached
+ *		from DETACHED or SHUTDOWN.
+ */
+enum clock_event_state {
+	CLOCK_EVT_STATE_DETACHED = 0,
+	CLOCK_EVT_STATE_SHUTDOWN,
+	CLOCK_EVT_STATE_PERIODIC,
+	CLOCK_EVT_STATE_ONESHOT,
 };
 
 /*
@@ -80,13 +96,14 @@ enum clock_event_mode {
  * @min_delta_ns:	minimum delta value in ns
  * @mult:		nanosecond to cycles multiplier
  * @shift:		nanoseconds to cycles divisor (power of two)
- * @mode:		operating mode assigned by the management code
+ * @mode:		operating mode, relevant only to ->set_mode(), OBSOLETE
+ * @state:		current state of the device, assigned by the core code
  * @features:		features
  * @retries:		number of forced programming retries
  * @set_mode:		legacy set mode function, only for modes <= CLOCK_EVT_MODE_RESUME.
- * @set_mode_periodic:	switch mode to periodic, if !set_mode
- * @set_mode_oneshot:	switch mode to oneshot, if !set_mode
- * @set_mode_shutdown:	switch mode to shutdown, if !set_mode
+ * @set_state_periodic:	switch state to periodic, if !set_mode
+ * @set_state_oneshot:	switch state to oneshot, if !set_mode
+ * @set_state_shutdown:	switch state to shutdown, if !set_mode
  * @tick_resume:	resume clkevt device, if !set_mode
  * @broadcast:		function to broadcast events
  * @min_delta_ticks:	minimum delta value in ticks stored for reconfiguration
@@ -111,20 +128,21 @@ struct clock_event_device {
 	u32			mult;
 	u32			shift;
 	enum clock_event_mode	mode;
+	enum clock_event_state	state;
 	unsigned int		features;
 	unsigned long		retries;
 
 	/*
-	 * Mode transition callback(s): Only one of the two groups should be
+	 * State transition callback(s): Only one of the two groups should be
 	 * defined:
 	 * - set_mode(), only for modes <= CLOCK_EVT_MODE_RESUME.
-	 * - set_mode_{shutdown|periodic|oneshot|resume}().
+	 * - set_state_{shutdown|periodic|oneshot}(), tick_resume().
 	 */
 	void			(*set_mode)(enum clock_event_mode mode,
 					    struct clock_event_device *);
-	int			(*set_mode_periodic)(struct clock_event_device *);
-	int			(*set_mode_oneshot)(struct clock_event_device *);
-	int			(*set_mode_shutdown)(struct clock_event_device *);
+	int			(*set_state_periodic)(struct clock_event_device *);
+	int			(*set_state_oneshot)(struct clock_event_device *);
+	int			(*set_state_shutdown)(struct clock_event_device *);
 	int			(*tick_resume)(struct clock_event_device *);
 
 	void			(*broadcast)(const struct cpumask *mask);
@@ -177,8 +195,8 @@ extern int clockevents_update_freq(struct clock_event_device *ce, u32 freq);
 
 extern void clockevents_exchange_device(struct clock_event_device *old,
 					struct clock_event_device *new);
-extern void clockevents_set_mode(struct clock_event_device *dev,
-				 enum clock_event_mode mode);
+extern void clockevents_set_state(struct clock_event_device *dev,
+				  enum clock_event_state state);
 extern int clockevents_program_event(struct clock_event_device *dev,
 				     ktime_t expires, bool force);