net: ipa: introduce ipa_uc_clock()

The first time it's booted, the modem loads and starts the
IPA-resident microcontroller.  Once the microcontroller has
completed its initialization, it notifies the AP it's "ready"
by sending an INIT_COMPLETED response message.

Until it receives that microcontroller message, the AP must ensure
the IPA core clock remains operational.  Currently, a "proxy" clock
reference is taken in ipa_uc_config(), dropping it again once the
message is received.

However there could be a long delay between when ipa_config()
completes and when modem actually starts.  And because the
microcontroller gets loaded by the modem, there's no need to
get the modem "proxy clock" until the first time it starts.

Create a new function ipa_uc_clock() which takes the "proxy" clock
reference for the microcontroller.  Call it when we get remoteproc
SSR notification that the modem is about to start.  Keep an
additional flag to record whether this proxy clock reference needs
to be dropped at shutdown time, and issue a warning if we get the
microcontroller message either before the clock reference is taken,
or after it has already been dropped.

Drop the nearby use of "hh" length modifiers, which are no longer
encouraged in the kernel.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/net/ipa/ipa_uc.h b/drivers/net/ipa/ipa_uc.h
index cb0a224022f5..14e4e1115aa7 100644
--- a/drivers/net/ipa/ipa_uc.h
+++ b/drivers/net/ipa/ipa_uc.h
@@ -21,6 +21,20 @@ void ipa_uc_config(struct ipa *ipa);
 void ipa_uc_deconfig(struct ipa *ipa);
 
 /**
+ * ipa_uc_clock() - Take a proxy clock reference for the microcontroller
+ * @ipa:	IPA pointer
+ *
+ * The first time the modem boots, it loads firmware for and starts the
+ * IPA-resident microcontroller.  The microcontroller signals that it
+ * has completed its initialization by sending an INIT_COMPLETED response
+ * message to the AP.  The AP must ensure the IPA core clock is operating
+ * until it receives this message, and to do so we take a "proxy" clock
+ * reference on its behalf here.  Once we receive the INIT_COMPLETED
+ * message (in ipa_uc_response_hdlr()) we drop this clock reference.
+ */
+void ipa_uc_clock(struct ipa *ipa);
+
+/**
  * ipa_uc_panic_notifier()
  * @ipa:	IPA pointer
  *