misc: add "call" uclass op

The call op requests that the callee pass a message to the underlying HW
or device, wait for a response, and then pass back the response error code
and message to the callee. It is useful for drivers that represent some
kind of messaging or IPC channel to a remote device.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>

drivers/misc/misc-uclass.c

@@ -45,6 +45,17 @@ int misc_ioctl(struct udevice *dev, unsigned long request, void *buf)
 	return ops->ioctl(dev, request, buf);
 }
 
+int misc_call(struct udevice *dev, int msgid, void *tx_msg, int tx_size,
+	      void *rx_msg, int rx_size)
+{
+	const struct misc_ops *ops = device_get_ops(dev);
+
+	if (!ops->call)
+		return -ENOSYS;
+
+	return ops->call(dev, msgid, tx_msg, tx_size, rx_msg, rx_size);
+}
+
 UCLASS_DRIVER(misc) = {
 	.id		= UCLASS_MISC,
 	.name		= "misc",

include/misc.h

@@ -37,6 +37,27 @@ int misc_write(struct udevice *dev, int offset, void *buf, int size);
  */
 int misc_ioctl(struct udevice *dev, unsigned long request, void *buf);
 
+/*
+ * Send a message to the device and wait for a response.
+ *
+ * The caller provides the message type/ID and payload to be sent.
+ * The callee constructs any message header required, transmits it to the
+ * target, waits for a response, checks any error code in the response,
+ * strips any message header from the response, and returns the error code
+ * (or a parsed version of it) and the response message payload.
+ *
+ * @dev: the device.
+ * @msgid: the message ID/number to send.
+ * tx_msg: the request/transmit message payload.
+ * tx_size: the size of the buffer pointed at by tx_msg.
+ * rx_msg: the buffer to receive the response message payload. May be NULL if
+ *         the caller only cares about the error code.
+ * rx_size: the size of the buffer pointed at by rx_msg.
+ * @return the response message size if OK, -ve on error
+ */
+int misc_call(struct udevice *dev, int msgid, void *tx_msg, int tx_size,
+	      void *rx_msg, int rx_size);
+
 /*
  * struct misc_ops - Driver model Misc operations
  *
@@ -74,6 +95,20 @@ struct misc_ops {
 	 * @return: 0 if OK, -ve on error
 	 */
 	int (*ioctl)(struct udevice *dev, unsigned long request, void *buf);
+	/*
+	 * Send a message to the device and wait for a response.
+	 *
+	 * @dev: the device
+	 * @msgid: the message ID/number to send
+	 * tx_msg: the request/transmit message payload
+	 * tx_size: the size of the buffer pointed at by tx_msg
+	 * rx_msg: the buffer to receive the response message payload. May be
+	 *         NULL if the caller only cares about the error code.
+	 * rx_size: the size of the buffer pointed at by rx_msg
+	 * @return the response message size if OK, -ve on error
+	 */
+	int (*call)(struct udevice *dev, int msgid, void *tx_msg, int tx_size,
+		    void *rx_msg, int rx_size);
 };
 
 #endif	/* _MISC_H_ */