slimbus: Add messaging APIs to slimbus framework

SLIMbus devices use value-element, and information elements to
control device parameters (e.g. value element is used to represent
gain for codec, information element is used to represent interrupt
status for codec when codec interrupt fires).
Messaging APIs are used to set/get these value and information
elements. SLIMbus specification uses 8-bit "transaction IDs" for
messages where a read-value is anticipated. Framework uses a table
of pointers to store those TIDs and responds back to the caller in
O(1).
Caller can do synchronous and asynchronous reads/writes.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviwed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 67 insertions, 0 deletions

diff --git a/drivers/slimbus/slimbus.h b/drivers/slimbus/slimbus.h
index 66657722f50f..0d40c2578c28 100644
--- a/drivers/slimbus/slimbus.h
+++ b/drivers/slimbus/slimbus.h
@@ -8,8 +8,17 @@
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/mutex.h>
+#include <linux/completion.h>
 #include <linux/slimbus.h>
 
+/* SLIMbus message types. Related to interpretation of message code. */
+#define SLIM_MSG_MT_CORE			0x0
+
+/* Destination type Values */
+#define SLIM_MSG_DEST_LOGICALADDR	0
+#define SLIM_MSG_DEST_ENUMADDR		1
+#define	SLIM_MSG_DEST_BROADCAST		3
+
 /* Standard values per SLIMbus spec needed by controllers and devices */
 #define SLIM_MAX_CLK_GEAR		10
 #define SLIM_MIN_CLK_GEAR		1
@@ -17,6 +26,7 @@
 /* Manager's logical address is set to 0xFF per spec */
 #define SLIM_LA_MANAGER 0xFF
 
+#define SLIM_MAX_TIDS			256
 /**
  * struct slim_framer - Represents SLIMbus framer.
  * Every controller may have multiple framers. There is 1 active framer device
@@ -38,6 +48,39 @@ struct slim_framer {
 #define to_slim_framer(d) container_of(d, struct slim_framer, dev)
 
 /**
+ * struct slim_msg_txn - Message to be sent by the controller.
+ *			This structure has packet header,
+ *			payload and buffer to be filled (if any)
+ * @rl: Header field. remaining length.
+ * @mt: Header field. Message type.
+ * @mc: Header field. LSB is message code for type mt.
+ * @dt: Header field. Destination type.
+ * @ec: Element code. Used for elemental access APIs.
+ * @tid: Transaction ID. Used for messages expecting response.
+ *	(relevant for message-codes involving read operation)
+ * @la: Logical address of the device this message is going to.
+ *	(Not used when destination type is broadcast.)
+ * @msg: Elemental access message to be read/written
+ * @comp: completion if read/write is synchronous, used internally
+ *	for tid based transactions.
+ */
+struct slim_msg_txn {
+	u8			rl;
+	u8			mt;
+	u8			mc;
+	u8			dt;
+	u16			ec;
+	u8			tid;
+	u8			la;
+	struct slim_val_inf	*msg;
+	struct	completion	*comp;
+};
+
+/* Frequently used message transaction structures */
+#define DEFINE_SLIM_LDEST_TXN(name, mc, rl, la, msg) \
+	struct slim_msg_txn name = { rl, 0, mc, SLIM_MSG_DEST_LOGICALADDR, 0,\
+					0, la, msg, }
+/**
  * struct slim_controller  - Controls every instance of SLIMbus
  *				(similar to 'master' on SPI)
  * @dev: Device interface to this driver
@@ -52,6 +95,9 @@ struct slim_framer {
  * @devices: Slim device list
  * @tid_idr: tid id allocator
  * @txn_lock: Lock to protect table of transactions
+ * @xfer_msg: Transfer a message on this controller (this can be a broadcast
+ *	control/status message like data channel setup, or a unicast message
+ *	like value element read/write.
  * @set_laddr: Setup logical address at laddr for the slave with elemental
  *	address e_addr. Drivers implementing controller will be expected to
  *	send unicast message to this device with its logical address.
@@ -93,6 +139,8 @@ struct slim_controller {
 	struct list_head	devices;
 	struct idr		tid_idr;
 	spinlock_t		txn_lock;
+	int			(*xfer_msg)(struct slim_controller *ctrl,
+					    struct slim_msg_txn *tx);
 	int			(*set_laddr)(struct slim_controller *ctrl,
 					     struct slim_eaddr *ea, u8 laddr);
 	int			(*get_laddr)(struct slim_controller *ctrl,
@@ -104,5 +152,24 @@ int slim_device_report_present(struct slim_controller *ctrl,
 void slim_report_absent(struct slim_device *sbdev);
 int slim_register_controller(struct slim_controller *ctrl);
 int slim_unregister_controller(struct slim_controller *ctrl);
+void slim_msg_response(struct slim_controller *ctrl, u8 *reply, u8 tid, u8 l);
+int slim_do_transfer(struct slim_controller *ctrl, struct slim_msg_txn *txn);
+
+static inline bool slim_tid_txn(u8 mt, u8 mc)
+{
+	return (mt == SLIM_MSG_MT_CORE &&
+		(mc == SLIM_MSG_MC_REQUEST_INFORMATION ||
+		 mc == SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION ||
+		 mc == SLIM_MSG_MC_REQUEST_VALUE ||
+		 mc == SLIM_MSG_MC_REQUEST_CLEAR_INFORMATION));
+}
 
+static inline bool slim_ec_txn(u8 mt, u8 mc)
+{
+	return (mt == SLIM_MSG_MT_CORE &&
+		((mc >= SLIM_MSG_MC_REQUEST_INFORMATION &&
+		  mc <= SLIM_MSG_MC_REPORT_INFORMATION) ||
+		 (mc >= SLIM_MSG_MC_REQUEST_VALUE &&
+		  mc <= SLIM_MSG_MC_CHANGE_VALUE)));
+}
 #endif /* _LINUX_SLIMBUS_H */