Add bridged amplifiers to cs42l43

Merge series from Charles Keepax <ckeepax@opensource.cirrus.com>:

In some cs42l43 systems a couple of cs35l56 amplifiers are attached
to the cs42l43's SPI and I2S. On Windows the cs42l43 is controlled
by a SDCA class driver and these two amplifiers are controlled by
firmware running on the cs42l43. However, under Linux the decision
was made to interact with the cs42l43 directly, affording the user
greater control over the audio system. However, this has resulted
in an issue where these two bridged cs35l56 amplifiers are not
populated in ACPI and must be added manually. There is at least an
SDCA extension unit DT entry we can key off.

The process of adding this is handled using a software node, firstly the
ability to add native chip selects to software nodes must be added.
Secondly, an additional flag for naming the SPI devices is added this
allows the machine driver to key to the correct amplifier. Then finally,
the cs42l43 SPI driver adds the two amplifiers directly onto its SPI
bus.

An additional series will follow soon to add the audio machine driver
parts (in the sof-sdw driver), however that is fairly orthogonal to
this part of the process, getting the actual amplifiers registered.

1 files changed, 31 insertions, 1 deletions

diff --git a/kernel/time/timer_migration.c b/kernel/time/timer_migration.c
index c63a0afdcebe..ccba875d2234 100644
--- a/kernel/time/timer_migration.c
+++ b/kernel/time/timer_migration.c
@@ -751,6 +751,33 @@ bool tmigr_update_events(struct tmigr_group *group, struct tmigr_group *child,
 
 		first_childevt = evt = data->evt;
 
+		/*
+		 * Walking the hierarchy is required in any case when a
+		 * remote expiry was done before. This ensures to not lose
+		 * already queued events in non active groups (see section
+		 * "Required event and timerqueue update after a remote
+		 * expiry" in the documentation at the top).
+		 *
+		 * The two call sites which are executed without a remote expiry
+		 * before, are not prevented from propagating changes through
+		 * the hierarchy by the return:
+		 *  - When entering this path by tmigr_new_timer(), @evt->ignore
+		 *    is never set.
+		 *  - tmigr_inactive_up() takes care of the propagation by
+		 *    itself and ignores the return value. But an immediate
+		 *    return is possible if there is a parent, sparing group
+		 *    locking at this level, because the upper walking call to
+		 *    the parent will take care about removing this event from
+		 *    within the group and update next_expiry accordingly.
+		 *
+		 * However if there is no parent, ie: the hierarchy has only a
+		 * single level so @group is the top level group, make sure the
+		 * first event information of the group is updated properly and
+		 * also handled properly, so skip this fast return path.
+		 */
+		if (evt->ignore && !remote && group->parent)
+			return true;
+
 		raw_spin_lock(&group->lock);
 
 		childstate.state = 0;
@@ -762,8 +789,11 @@ bool tmigr_update_events(struct tmigr_group *group, struct tmigr_group *child,
 	 * queue when the expiry time changed only or when it could be ignored.
 	 */
 	if (timerqueue_node_queued(&evt->nextevt)) {
-		if ((evt->nextevt.expires == nextexp) && !evt->ignore)
+		if ((evt->nextevt.expires == nextexp) && !evt->ignore) {
+			/* Make sure not to miss a new CPU event with the same expiry */
+			evt->cpu = first_childevt->cpu;
 			goto check_toplvl;
+		}
 
 		if (!timerqueue_del(&group->events, &evt->nextevt))
 			WRITE_ONCE(group->next_expiry, KTIME_MAX);