drivers: qcom: rpmh: allow requests to be sent asynchronously

Platform drivers that want to send a request but do not want to block
until the RPMH request completes have now a new API -
rpmh_write_async().

The API allocates memory and send the requests and returns the control
back to the platform driver. The tx_done callback from the controller is
handled in the context of the controller's thread and frees the
allocated memory. This API allows RPMH requests from atomic contexts as
well.

Signed-off-by: Lina Iyer <ilina@codeaurora.org>
Signed-off-by: Raju P.L.S.S.S.N <rplsssn@codeaurora.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>

include/soc/qcom/rpmh.h

@@ -14,6 +14,9 @@
 int rpmh_write(const struct device *dev, enum rpmh_state state,
 	       const struct tcs_cmd *cmd, u32 n);
 
+int rpmh_write_async(const struct device *dev, enum rpmh_state state,
+		     const struct tcs_cmd *cmd, u32 n);
+
 int rpmh_flush(const struct device *dev);
 
 int rpmh_invalidate(const struct device *dev);
@@ -24,6 +27,10 @@ static inline int rpmh_write(const struct device *dev, enum rpmh_state state,
 			     const struct tcs_cmd *cmd, u32 n)
 { return -ENODEV; }
 
+static inline int rpmh_write_async(const struct device *dev,
+				   enum rpmh_state state,
+				   const struct tcs_cmd *cmd, u32 n)
+{ return -ENODEV; }
 
 static inline int rpmh_flush(const struct device *dev)
 { return -ENODEV; }