pru: Add initial pru_rpmsg library code for Beaglebone PRU

Add external code for using RPMsg on the Beaglebone PRU.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

lib/pru_rpmsg/pru_rpmsg.c

@@ -0,0 +1,186 @@
+/*
+ * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *	* Redistributions of source code must retain the above copyright
+ *	  notice, this list of conditions and the following disclaimer.
+ *
+ *	* Redistributions in binary form must reproduce the above copyright
+ *	  notice, this list of conditions and the following disclaimer in the
+ *	  documentation and/or other materials provided with the
+ *	  distribution.
+ *
+ *	* Neither the name of Texas Instruments Incorporated nor the names of
+ *	  its contributors may be used to endorse or promote products derived
+ *	  from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ *  File	:	pru_rpmsg.c
+ *
+ *  Summary	:	An RPMsg implementation for the PRU to use while communicating
+ *			with the ARM host.
+ *
+ *  Notes	:
+ *  - Implementaion of the interface described in "pru_rpmsg.h"
+ */
+
+#include <string.h>
+#include <pru_rpmsg.h>
+
+struct pru_rpmsg_hdr {
+	uint32_t	src;
+	uint32_t	dst;
+	uint32_t	reserved;
+	uint16_t	len;
+	uint16_t	flags;
+	uint8_t		data[0];
+};
+
+struct pru_rpmsg_ns_msg {
+	char		name[RPMSG_NAME_SIZE];
+	char		desc[RPMSG_NAME_SIZE];
+	uint32_t	addr;
+	uint32_t	flags;
+};
+
+int16_t pru_rpmsg_init(
+	struct pru_rpmsg_transport	*transport,
+	struct fw_rsc_vdev_vring 	*vring0,
+	struct fw_rsc_vdev_vring 	*vring1,
+	uint32_t 			to_arm_event,
+	uint32_t 			from_arm_event
+)
+{
+	if (to_arm_event > MAX_VALID_EVENT || to_arm_event < MIN_VALID_EVENT)
+		return PRU_RPMSG_INVALID_EVENT;
+
+	if (from_arm_event > MAX_VALID_EVENT || from_arm_event < MIN_VALID_EVENT)
+		return PRU_RPMSG_INVALID_EVENT;
+
+	pru_virtqueue_init(&transport->virtqueue0, vring0, to_arm_event, from_arm_event);
+	pru_virtqueue_init(&transport->virtqueue1, vring1, to_arm_event, from_arm_event);
+
+	return PRU_RPMSG_SUCCESS;
+}
+
+int16_t pru_rpmsg_send(
+    struct pru_rpmsg_transport	*transport,
+    uint32_t			src,
+    uint32_t			dst,
+    void			*data,
+    uint16_t			len
+)
+{
+	struct pru_rpmsg_hdr	*msg;
+	uint32_t		msg_len;
+	int16_t			head;
+	struct pru_virtqueue	*virtqueue;
+
+	/*
+	 * The length of our payload is larger than the maximum RPMsg buffer size
+	 * allowed
+	 */
+	if (len > (RPMSG_BUF_SIZE - sizeof(struct pru_rpmsg_hdr)))
+		return PRU_RPMSG_BUF_TOO_SMALL;
+
+	virtqueue = &transport->virtqueue0;
+
+	/* Get an available buffer */
+	head = pru_virtqueue_get_avail_buf(virtqueue, (void **)&msg, &msg_len);
+
+	if (head < 0)
+		return PRU_RPMSG_NO_BUF_AVAILABLE;
+
+	/* Copy local data buffer to the descriptor buffer address */
+	memcpy(msg->data, data, len);
+	msg->len = len;
+	msg->dst = dst;
+	msg->src = src;
+	msg->flags = 0;
+	msg->reserved = 0;
+
+	/* Add the used buffer */
+	if (pru_virtqueue_add_used_buf(virtqueue, head, msg_len) < 0)
+		return PRU_RPMSG_INVALID_HEAD;
+
+	/* Kick the ARM host */
+	pru_virtqueue_kick(virtqueue);
+
+	return PRU_RPMSG_SUCCESS;
+}
+
+int16_t pru_rpmsg_receive(
+    struct pru_rpmsg_transport	*transport,
+    uint16_t			*src,
+    uint16_t			*dst,
+    void			*data,
+    uint16_t			*len
+)
+{
+	int16_t			head;
+	struct pru_rpmsg_hdr	*msg;
+	uint32_t		msg_len;
+	struct pru_virtqueue	*virtqueue;
+
+	virtqueue = &transport->virtqueue1;
+
+	/* Get an available buffer */
+	head = pru_virtqueue_get_avail_buf(virtqueue, (void **)&msg, &msg_len);
+
+	if (head < 0)
+		return PRU_RPMSG_NO_BUF_AVAILABLE;
+
+
+	/* Copy the message payload to the local data buffer provided */
+	memcpy(data, msg->data, msg->len);
+	*src = msg->src;
+	*dst = msg->dst;
+	*len = msg->len;
+
+	/* Add the used buffer */
+	if (pru_virtqueue_add_used_buf(virtqueue, head, msg_len) < 0)
+		return PRU_RPMSG_INVALID_HEAD;
+
+	/* Kick the ARM host */
+	pru_virtqueue_kick(virtqueue);
+
+	return PRU_RPMSG_SUCCESS;
+}
+
+int16_t pru_rpmsg_channel(
+    enum pru_rpmsg_ns_flags	flags,
+    struct pru_rpmsg_transport	*transport,
+    char			*name,
+    char			*desc,
+    int32_t			port
+)
+{
+	struct pru_rpmsg_ns_msg	ns_msg;
+	uint8_t			i;
+
+	for (i = 0; i < RPMSG_NAME_SIZE; i++) {
+		ns_msg.name[i] = name[i];
+		ns_msg.desc[i] = desc[i];
+	}
+	ns_msg.addr = port;
+	ns_msg.flags = flags;
+
+	return pru_rpmsg_send(transport, port, 53, &ns_msg, sizeof(ns_msg));
+}