text: /*
   * Copyright (c) 2016-2017, Linaro Ltd
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 and
   * only version 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   */
  
  #include <linux/idr.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/list.h>
  #include <linux/mfd/syscon.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/platform_device.h>
  #include <linux/regmap.h>
  #include <linux/rpmsg.h>
  #include <linux/slab.h>
  #include <linux/workqueue.h>
  #include <linux/mailbox_client.h>
  
  #include "rpmsg_internal.h"
  
  #define RPM_TOC_SIZE		256
  #define RPM_TOC_MAGIC		0x67727430 /* grt0 */
  #define RPM_TOC_MAX_ENTRIES	((RPM_TOC_SIZE - sizeof(struct rpm_toc)) / \
  				 sizeof(struct rpm_toc_entry))
  
  #define RPM_TX_FIFO_ID		0x61703272 /* ap2r */
  #define RPM_RX_FIFO_ID		0x72326170 /* r2ap */
  
  #define GLINK_NAME_SIZE		32
  
  #define RPM_GLINK_CID_MIN	1
  #define RPM_GLINK_CID_MAX	65536
  
  struct rpm_toc_entry {
  	__le32 id;
  	__le32 offset;
  	__le32 size;
  } __packed;
  
  struct rpm_toc {
  	__le32 magic;
  	__le32 count;
  
  	struct rpm_toc_entry entries[];
  } __packed;
  
  struct glink_msg {
  	__le16 cmd;
  	__le16 param1;
  	__le32 param2;
  	u8 data[];
  } __packed;
  
  struct glink_rpm_pipe {
  	void __iomem *tail;
  	void __iomem *head;
  
  	void __iomem *fifo;
  
  	size_t length;
  };
  
  /**
   * struct glink_defer_cmd - deferred incoming control message
   * @node:	list node
   * @msg:	message header
   * data:	payload of the message
   *
   * Copy of a received control message, to be added to @rx_queue and processed
   * by @rx_work of @glink_rpm.
   */
  struct glink_defer_cmd {
  	struct list_head node;
  
  	struct glink_msg msg;
  	u8 data[];
  };
  
  /**
   * struct glink_rpm - driver context, relates to one remote subsystem
   * @dev:	reference to the associated struct device
   * @doorbell:	"rpm_hlos" ipc doorbell
   * @rx_pipe:	pipe object for receive FIFO
   * @tx_pipe:	pipe object for transmit FIFO
   * @irq:	IRQ for signaling incoming events
   * @rx_work:	worker for handling received control messages
   * @rx_lock:	protects the @rx_queue
   * @rx_queue:	queue of received control messages to be processed in @rx_work
   * @tx_lock:	synchronizes operations on the tx fifo
   * @idr_lock:	synchronizes @lcids and @rcids modifications
   * @lcids:	idr of all channels with a known local channel id
   * @rcids:	idr of all channels with a known remote channel id
   */
  struct glink_rpm {
  	struct device *dev;
  
  	struct mbox_client mbox_client;
  	struct mbox_chan *mbox_chan;
  
  	struct glink_rpm_pipe rx_pipe;
  	struct glink_rpm_pipe tx_pipe;
  
  	int irq;
  
  	struct work_struct rx_work;
  	spinlock_t rx_lock;
  	struct list_head rx_queue;
  
  	struct mutex tx_lock;
  
  	struct mutex idr_lock;
  	struct idr lcids;
  	struct idr rcids;
  };
  
  enum {
  	GLINK_STATE_CLOSED,
  	GLINK_STATE_OPENING,
  	GLINK_STATE_OPEN,
  	GLINK_STATE_CLOSING,
  };
  
  /**
   * struct glink_channel - internal representation of a channel
   * @rpdev:	rpdev reference, only used for primary endpoints
   * @ept:	rpmsg endpoint this channel is associated with
   * @glink:	glink_rpm context handle
   * @refcount:	refcount for the channel object
   * @recv_lock:	guard for @ept.cb
   * @name:	unique channel name/identifier
   * @lcid:	channel id, in local space
   * @rcid:	channel id, in remote space
   * @buf:	receive buffer, for gathering fragments
   * @buf_offset:	write offset in @buf
   * @buf_size:	size of current @buf
   * @open_ack:	completed once remote has acked the open-request
   * @open_req:	completed once open-request has been received
   */
  struct glink_channel {
  	struct rpmsg_endpoint ept;
  
  	struct rpmsg_device *rpdev;
  	struct glink_rpm *glink;
  
  	struct kref refcount;
  
  	spinlock_t recv_lock;
  
  	char *name;
  	unsigned int lcid;
  	unsigned int rcid;
  
  	void *buf;
  	int buf_offset;
  	int buf_size;
  
  	struct completion open_ack;
  	struct completion open_req;
  };
  
  #define to_glink_channel(_ept) container_of(_ept, struct glink_channel, ept)
  
  static const struct rpmsg_endpoint_ops glink_endpoint_ops;
  
  #define RPM_CMD_VERSION			0
  #define RPM_CMD_VERSION_ACK		1
  #define RPM_CMD_OPEN			2
  #define RPM_CMD_CLOSE			3
  #define RPM_CMD_OPEN_ACK		4
  #define RPM_CMD_TX_DATA			9
  #define RPM_CMD_CLOSE_ACK		11
  #define RPM_CMD_TX_DATA_CONT		12
  #define RPM_CMD_READ_NOTIF		13
  
  #define GLINK_FEATURE_INTENTLESS	BIT(1)
  
  static struct glink_channel *glink_rpm_alloc_channel(struct glink_rpm *glink,
  						     const char *name)
  {
  	struct glink_channel *channel;
  
  	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
  	if (!channel)
  		return ERR_PTR(-ENOMEM);
  
  	/* Setup glink internal glink_channel data */
  	spin_lock_init(&channel->recv_lock);
  	channel->glink = glink;
  	channel->name = kstrdup(name, GFP_KERNEL);
  
  	init_completion(&channel->open_req);
  	init_completion(&channel->open_ack);
  
  	kref_init(&channel->refcount);
  
  	return channel;
  }
  
  static void glink_rpm_channel_release(struct kref *ref)
  {
  	struct glink_channel *channel = container_of(ref, struct glink_channel,
  						     refcount);
  
  	kfree(channel->name);
  	kfree(channel);
  }
  
  static size_t glink_rpm_rx_avail(struct glink_rpm *glink)
  {
  	struct glink_rpm_pipe *pipe = &glink->rx_pipe;
  	unsigned int head;
  	unsigned int tail;
  
  	head = readl(pipe->head);
  	tail = readl(pipe->tail);
  
  	if (head < tail)
  		return pipe->length - tail + head;
  	else
  		return head - tail;
  }
  
  static void glink_rpm_rx_peak(struct glink_rpm *glink,
  			      void *data, size_t count)
  {
  	struct glink_rpm_pipe *pipe = &glink->rx_pipe;
  	unsigned int tail;
  	size_t len;
  
  	tail = readl(pipe->tail);
  
  	len = min_t(size_t, count, pipe->length - tail);
  	if (len) {
  		__ioread32_copy(data, pipe->fifo + tail,
  				len / sizeof(u32));
  	}
  
  	if (len != count) {
  		__ioread32_copy(data + len, pipe->fifo,
  				(count - len) / sizeof(u32));
  	}
  }
  
  static void glink_rpm_rx_advance(struct glink_rpm *glink,
  				 size_t count)
  {
  	struct glink_rpm_pipe *pipe = &glink->rx_pipe;
  	unsigned int tail;
  
  	tail = readl(pipe->tail);
  
  	tail += count;
  	if (tail >= pipe->length)
  		tail -= pipe->length;
  
  	writel(tail, pipe->tail);
  }
  
  static size_t glink_rpm_tx_avail(struct glink_rpm *glink)
  {
  	struct glink_rpm_pipe *pipe = &glink->tx_pipe;
  	unsigned int head;
  	unsigned int tail;
  
  	head = readl(pipe->head);
  	tail = readl(pipe->tail);
  
  	if (tail <= head)
  		return pipe->length - head + tail;
  	else
  		return tail - head;
  }
  
  static unsigned int glink_rpm_tx_write(struct glink_rpm *glink,
  				       unsigned int head,
  				       const void *data, size_t count)
  {
  	struct glink_rpm_pipe *pipe = &glink->tx_pipe;
  	size_t len;
  
  	len = min_t(size_t, count, pipe->length - head);
  	if (len) {
  		__iowrite32_copy(pipe->fifo + head, data,
  				 len / sizeof(u32));
  	}
  
  	if (len != count) {
  		__iowrite32_copy(pipe->fifo, data + len,
  				 (count - len) / sizeof(u32));
  	}
  
  	head += count;
  	if (head >= pipe->length)
  		head -= pipe->length;
  
  	return head;
  }
  
  static int glink_rpm_tx(struct glink_rpm *glink,
  			const void *hdr, size_t hlen,
  			const void *data, size_t dlen, bool wait)
  {
  	struct glink_rpm_pipe *pipe = &glink->tx_pipe;
  	unsigned int head;
  	unsigned int tlen = hlen + dlen;
  	int ret;
  
  	/* Reject packets that are too big */
  	if (tlen >= glink->tx_pipe.length)
  		return -EINVAL;
  
  	if (WARN(tlen % 8, "Unaligned TX request"))
  		return -EINVAL;
  
  	ret = mutex_lock_interruptible(&glink->tx_lock);
  	if (ret)
  		return ret;
  
  	while (glink_rpm_tx_avail(glink) < tlen) {
  		if (!wait) {
  			ret = -ENOMEM;
  			goto out;
  		}
  
  		msleep(10);
  	}
  
  	head = readl(pipe->head);
  	head = glink_rpm_tx_write(glink, head, hdr, hlen);
  	head = glink_rpm_tx_write(glink, head, data, dlen);
  	writel(head, pipe->head);
  
  	mbox_send_message(glink->mbox_chan, NULL);
  	mbox_client_txdone(glink->mbox_chan, 0);
  
  out:
  	mutex_unlock(&glink->tx_lock);
  
  	return ret;
  }
  
  static int glink_rpm_send_version(struct glink_rpm *glink)
  {
  	struct glink_msg msg;
  
  	msg.cmd = cpu_to_le16(RPM_CMD_VERSION);
  	msg.param1 = cpu_to_le16(1);
  	msg.param2 = cpu_to_le32(GLINK_FEATURE_INTENTLESS);
  
  	return glink_rpm_tx(glink, &msg, sizeof(msg), NULL, 0, true);
  }
  
  static void glink_rpm_send_version_ack(struct glink_rpm *glink)
  {
  	struct glink_msg msg;
  
  	msg.cmd = cpu_to_le16(RPM_CMD_VERSION_ACK);
  	msg.param1 = cpu_to_le16(1);
  	msg.param2 = cpu_to_le32(0);
  
  	glink_rpm_tx(glink, &msg, sizeof(msg), NULL, 0, true);
  }
  
  static void glink_rpm_send_open_ack(struct glink_rpm *glink,
  					 struct glink_channel *channel)
  {
  	struct glink_msg msg;
  
  	msg.cmd = cpu_to_le16(RPM_CMD_OPEN_ACK);
  	msg.param1 = cpu_to_le16(channel->rcid);
  	msg.param2 = cpu_to_le32(0);
  
  	glink_rpm_tx(glink, &msg, sizeof(msg), NULL, 0, true);
  }
  
  /**
   * glink_rpm_send_open_req() - send a RPM_CMD_OPEN request to the remote
   * @glink:
   * @channel:
   *
   * Allocates a local channel id and sends a RPM_CMD_OPEN message to the remote.
   * Will return with refcount held, regardless of outcome.
   *
   * Returns 0 on success, negative errno otherwise.
   */
  static int glink_rpm_send_open_req(struct glink_rpm *glink,
  					 struct glink_channel *channel)
  {
  	struct {
  		struct glink_msg msg;
  		u8 name[GLINK_NAME_SIZE];
  	} __packed req;
  	int name_len = strlen(channel->name) + 1;
  	int req_len = ALIGN(sizeof(req.msg) + name_len, 8);
  	int ret;
  
  	kref_get(&channel->refcount);
  
  	mutex_lock(&glink->idr_lock);
  	ret = idr_alloc_cyclic(&glink->lcids, channel,
  			       RPM_GLINK_CID_MIN, RPM_GLINK_CID_MAX, GFP_KERNEL);
  	mutex_unlock(&glink->idr_lock);
  	if (ret < 0)
  		return ret;
  
  	channel->lcid = ret;
  
  	req.msg.cmd = cpu_to_le16(RPM_CMD_OPEN);
  	req.msg.param1 = cpu_to_le16(channel->lcid);
  	req.msg.param2 = cpu_to_le32(name_len);
  	strcpy(req.name, channel->name);
  
  	ret = glink_rpm_tx(glink, &req, req_len, NULL, 0, true);
  	if (ret)
  		goto remove_idr;
  
  	return 0;
  
  remove_idr:
  	mutex_lock(&glink->idr_lock);
  	idr_remove(&glink->lcids, channel->lcid);
  	channel->lcid = 0;
  	mutex_unlock(&glink->idr_lock);
  
  	return ret;
  }
  
  static void glink_rpm_send_close_req(struct glink_rpm *glink,
  					  struct glink_channel *channel)
  {
  	struct glink_msg req;
  
  	req.cmd = cpu_to_le16(RPM_CMD_CLOSE);
  	req.param1 = cpu_to_le16(channel->lcid);
  	req.param2 = 0;
  
  	glink_rpm_tx(glink, &req, sizeof(req), NULL, 0, true);
  }
  
  static void glink_rpm_send_close_ack(struct glink_rpm *glink, unsigned int rcid)
  {
  	struct glink_msg req;
  
  	req.cmd = cpu_to_le16(RPM_CMD_CLOSE_ACK);
  	req.param1 = cpu_to_le16(rcid);
  	req.param2 = 0;
  
  	glink_rpm_tx(glink, &req, sizeof(req), NULL, 0, true);
  }
  
  static int glink_rpm_rx_defer(struct glink_rpm *glink, size_t extra)
  {
  	struct glink_defer_cmd *dcmd;
  
  	extra = ALIGN(extra, 8);
  
  	if (glink_rpm_rx_avail(glink) < sizeof(struct glink_msg) + extra) {
  		dev_dbg(glink->dev, "Insufficient data in rx fifo");
  		return -ENXIO;
  	}
  
  	dcmd = kzalloc(sizeof(*dcmd) + extra, GFP_ATOMIC);
  	if (!dcmd)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&dcmd->node);
  
  	glink_rpm_rx_peak(glink, &dcmd->msg, sizeof(dcmd->msg) + extra);
  
  	spin_lock(&glink->rx_lock);
  	list_add_tail(&dcmd->node, &glink->rx_queue);
  	spin_unlock(&glink->rx_lock);
  
  	schedule_work(&glink->rx_work);
  	glink_rpm_rx_advance(glink, sizeof(dcmd->msg) + extra);
  
  	return 0;
  }
  
  static int glink_rpm_rx_data(struct glink_rpm *glink, size_t avail)
  {
  	struct glink_channel *channel;
  	struct {
  		struct glink_msg msg;
  		__le32 chunk_size;
  		__le32 left_size;
  	} __packed hdr;
  	unsigned int chunk_size;
  	unsigned int left_size;
  	unsigned int rcid;
  
  	if (avail < sizeof(hdr)) {
  		dev_dbg(glink->dev, "Not enough data in fifo\n");
  		return -EAGAIN;
  	}
  
  	glink_rpm_rx_peak(glink, &hdr, sizeof(hdr));
  	chunk_size = le32_to_cpu(hdr.chunk_size);
  	left_size = le32_to_cpu(hdr.left_size);
  
  	if (avail < sizeof(hdr) + chunk_size) {
  		dev_dbg(glink->dev, "Payload not yet in fifo\n");
  		return -EAGAIN;
  	}
  
  	if (WARN(chunk_size % 4, "Incoming data must be word aligned\n"))
  		return -EINVAL;
  
  	rcid = le16_to_cpu(hdr.msg.param1);
  	channel = idr_find(&glink->rcids, rcid);
  	if (!channel) {
  		dev_dbg(glink->dev, "Data on non-existing channel\n");
  
  		/* Drop the message */
  		glink_rpm_rx_advance(glink, ALIGN(sizeof(hdr) + chunk_size, 8));
  		return 0;
  	}
  
  	/* Might have an ongoing, fragmented, message to append */
  	if (!channel->buf) {
  		channel->buf = kmalloc(chunk_size + left_size, GFP_ATOMIC);
  		if (!channel->buf)
  			return -ENOMEM;
  
  		channel->buf_size = chunk_size + left_size;
  		channel->buf_offset = 0;
  	}
  
  	glink_rpm_rx_advance(glink, sizeof(hdr));
  
  	if (channel->buf_size - channel->buf_offset < chunk_size) {
  		dev_err(glink->dev, "Insufficient space in input buffer\n");
  
  		/* The packet header lied, drop payload */
  		glink_rpm_rx_advance(glink, chunk_size);
  		return -ENOMEM;
  	}
  
  	glink_rpm_rx_peak(glink, channel->buf + channel->buf_offset, chunk_size);
  	channel->buf_offset += chunk_size;
  
  	/* Handle message when no fragments remain to be received */
  	if (!left_size) {
  		spin_lock(&channel->recv_lock);
  		if (channel->ept.cb) {
  			channel->ept.cb(channel->ept.rpdev,
  					channel->buf,
  					channel->buf_offset,
  					channel->ept.priv,
  					RPMSG_ADDR_ANY);
  		}
  		spin_unlock(&channel->recv_lock);
  
  		kfree(channel->buf);
  		channel->buf = NULL;
  		channel->buf_size = 0;
  	}
  
  	/* Each message starts at 8 byte aligned address */
  	glink_rpm_rx_advance(glink, ALIGN(chunk_size, 8));
  
  	return 0;
  }
  
  static int glink_rpm_rx_open_ack(struct glink_rpm *glink, unsigned int lcid)
  {
  	struct glink_channel *channel;
  
  	channel = idr_find(&glink->lcids, lcid);
  	if (!channel) {
  		dev_err(glink->dev, "Invalid open ack packet\n");
  		return -EINVAL;
  	}
  
  	complete(&channel->open_ack);
  
  	return 0;
  }
  
  static irqreturn_t glink_rpm_intr(int irq, void *data)
  {
  	struct glink_rpm *glink = data;
  	struct glink_msg msg;
  	unsigned int param1;
  	unsigned int param2;
  	unsigned int avail;
  	unsigned int cmd;
  	int ret;
  
  	for (;;) {
  		avail = glink_rpm_rx_avail(glink);
  		if (avail < sizeof(msg))
  			break;
  
  		glink_rpm_rx_peak(glink, &msg, sizeof(msg));
  
  		cmd = le16_to_cpu(msg.cmd);
  		param1 = le16_to_cpu(msg.param1);
  		param2 = le32_to_cpu(msg.param2);
  
  		switch (cmd) {
  		case RPM_CMD_VERSION:
  		case RPM_CMD_VERSION_ACK:
  		case RPM_CMD_CLOSE:
  		case RPM_CMD_CLOSE_ACK:
  			ret = glink_rpm_rx_defer(glink, 0);
  			break;
  		case RPM_CMD_OPEN_ACK:
  			ret = glink_rpm_rx_open_ack(glink, param1);
  			glink_rpm_rx_advance(glink, ALIGN(sizeof(msg), 8));
  			break;
  		case RPM_CMD_OPEN:
  			ret = glink_rpm_rx_defer(glink, param2);
  			break;
  		case RPM_CMD_TX_DATA:
  		case RPM_CMD_TX_DATA_CONT:
  			ret = glink_rpm_rx_data(glink, avail);
  			break;
  		case RPM_CMD_READ_NOTIF:
  			glink_rpm_rx_advance(glink, ALIGN(sizeof(msg), 8));
  
  			mbox_send_message(glink->mbox_chan, NULL);
  			mbox_client_txdone(glink->mbox_chan, 0);
  
  			ret = 0;
  			break;
  		default:
  			dev_err(glink->dev, "unhandled rx cmd: %d\n", cmd);
  			ret = -EINVAL;
  			break;
  		}
  
  		if (ret)
  			break;
  	}
  
  	return IRQ_HANDLED;
  }
  
  /* Locally initiated rpmsg_create_ept */
  static struct glink_channel *glink_rpm_create_local(struct glink_rpm *glink,
  						    const char *name)
  {
  	struct glink_channel *channel;
  	int ret;
  
  	channel = glink_rpm_alloc_channel(glink, name);
  	if (IS_ERR(channel))
  		return ERR_CAST(channel);
  
  	ret = glink_rpm_send_open_req(glink, channel);
  	if (ret)
  		goto release_channel;
  
  	ret = wait_for_completion_timeout(&channel->open_ack, 5 * HZ);
  	if (!ret)
  		goto err_timeout;
  
  	ret = wait_for_completion_timeout(&channel->open_req, 5 * HZ);
  	if (!ret)
  		goto err_timeout;
  
  	glink_rpm_send_open_ack(glink, channel);
  
  	return channel;
  
  err_timeout:
  	/* glink_rpm_send_open_req() did register the channel in lcids*/
  	mutex_lock(&glink->idr_lock);
  	idr_remove(&glink->lcids, channel->lcid);
  	mutex_unlock(&glink->idr_lock);
  
  release_channel:
  	/* Release glink_rpm_send_open_req() reference */
  	kref_put(&channel->refcount, glink_rpm_channel_release);
  	/* Release glink_rpm_alloc_channel() reference */
  	kref_put(&channel->refcount, glink_rpm_channel_release);
  
  	return ERR_PTR(-ETIMEDOUT);
  }
  
  /* Remote initiated rpmsg_create_ept */
  static int glink_rpm_create_remote(struct glink_rpm *glink,
  				   struct glink_channel *channel)
  {
  	int ret;
  
  	glink_rpm_send_open_ack(glink, channel);
  
  	ret = glink_rpm_send_open_req(glink, channel);
  	if (ret)
  		goto close_link;
  
  	ret = wait_for_completion_timeout(&channel->open_ack, 5 * HZ);
  	if (!ret) {
  		ret = -ETIMEDOUT;
  		goto close_link;
  	}
  
  	return 0;
  
  close_link:
  	/*
  	 * Send a close request to "undo" our open-ack. The close-ack will
  	 * release the last reference.
  	 */
  	glink_rpm_send_close_req(glink, channel);
  
  	/* Release glink_rpm_send_open_req() reference */
  	kref_put(&channel->refcount, glink_rpm_channel_release);
  
  	return ret;
  }
  
  static struct rpmsg_endpoint *glink_rpm_create_ept(struct rpmsg_device *rpdev,
  						  rpmsg_rx_cb_t cb, void *priv,
  						  struct rpmsg_channel_info chinfo)
  {
  	struct glink_channel *parent = to_glink_channel(rpdev->ept);
  	struct glink_channel *channel;
  	struct glink_rpm *glink = parent->glink;
  	struct rpmsg_endpoint *ept;
  	const char *name = chinfo.name;
  	int cid;
  	int ret;
  
  	idr_for_each_entry(&glink->rcids, channel, cid) {
  		if (!strcmp(channel->name, name))
  			break;
  	}
  
  	if (!channel) {
  		channel = glink_rpm_create_local(glink, name);
  		if (IS_ERR(channel))
  			return NULL;
  	} else {
  		ret = glink_rpm_create_remote(glink, channel);
  		if (ret)
  			return NULL;
  	}
  
  	ept = &channel->ept;
  	ept->rpdev = rpdev;
  	ept->cb = cb;
  	ept->priv = priv;
  	ept->ops = &glink_endpoint_ops;
  
  	return ept;
  }
  
  static void glink_rpm_destroy_ept(struct rpmsg_endpoint *ept)
  {
  	struct glink_channel *channel = to_glink_channel(ept);
  	struct glink_rpm *glink = channel->glink;
  	unsigned long flags;
  
  	spin_lock_irqsave(&channel->recv_lock, flags);
  	channel->ept.cb = NULL;
  	spin_unlock_irqrestore(&channel->recv_lock, flags);
  
  	/* Decouple the potential rpdev from the channel */
  	channel->rpdev = NULL;
  
  	glink_rpm_send_close_req(glink, channel);
  }
  
  static int __glink_rpm_send(struct glink_channel *channel,
  			     void *data, int len, bool wait)
  {
  	struct glink_rpm *glink = channel->glink;
  	struct {
  		struct glink_msg msg;
  		__le32 chunk_size;
  		__le32 left_size;
  	} __packed req;
  
  	if (WARN(len % 8, "RPM GLINK expects 8 byte aligned messages\n"))
  		return -EINVAL;
  
  	req.msg.cmd = cpu_to_le16(RPM_CMD_TX_DATA);
  	req.msg.param1 = cpu_to_le16(channel->lcid);
  	req.msg.param2 = cpu_to_le32(channel->rcid);
  	req.chunk_size = cpu_to_le32(len);
  	req.left_size = cpu_to_le32(0);
  
  	return glink_rpm_tx(glink, &req, sizeof(req), data, len, wait);
  }
  
  static int glink_rpm_send(struct rpmsg_endpoint *ept, void *data, int len)
  {
  	struct glink_channel *channel = to_glink_channel(ept);
  
  	return __glink_rpm_send(channel, data, len, true);
  }
  
  static int glink_rpm_trysend(struct rpmsg_endpoint *ept, void *data, int len)
  {
  	struct glink_channel *channel = to_glink_channel(ept);
  
  	return __glink_rpm_send(channel, data, len, false);
  }
  
  /*
   * Finds the device_node for the glink child interested in this channel.
   */
  static struct device_node *glink_rpm_match_channel(struct device_node *node,
  						    const char *channel)
  {
  	struct device_node *child;
  	const char *name;
  	const char *key;
  	int ret;
  
  	for_each_available_child_of_node(node, child) {
  		key = "qcom,glink-channels";
  		ret = of_property_read_string(child, key, &name);
  		if (ret)
  			continue;
  
  		if (strcmp(name, channel) == 0)
  			return child;
  	}
  
  	return NULL;
  }
  
  static const struct rpmsg_device_ops glink_device_ops = {
  	.create_ept = glink_rpm_create_ept,
  };
  
  static const struct rpmsg_endpoint_ops glink_endpoint_ops = {
  	.destroy_ept = glink_rpm_destroy_ept,
  	.send = glink_rpm_send,
  	.trysend = glink_rpm_trysend,
  };
  
  static void glink_rpm_rpdev_release(struct device *dev)
  {
  	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
  	struct glink_channel *channel = to_glink_channel(rpdev->ept);
  
  	channel->rpdev = NULL;
  	kfree(rpdev);
  }
  
  static int glink_rpm_rx_open(struct glink_rpm *glink, unsigned int rcid,
  			     char *name)
  {
  	struct glink_channel *channel;
  	struct rpmsg_device *rpdev;
  	bool create_device = false;
  	int lcid;
  	int ret;
  
  	idr_for_each_entry(&glink->lcids, channel, lcid) {
  		if (!strcmp(channel->name, name))
  			break;
  	}
  
  	if (!channel) {
  		channel = glink_rpm_alloc_channel(glink, name);
  		if (IS_ERR(channel))
  			return PTR_ERR(channel);
  
  		/* The opening dance was initiated by the remote */
  		create_device = true;
  	}
  
  	mutex_lock(&glink->idr_lock);
  	ret = idr_alloc(&glink->rcids, channel, rcid, rcid + 1, GFP_KERNEL);
  	if (ret < 0) {
  		dev_err(glink->dev, "Unable to insert channel into rcid list\n");
  		mutex_unlock(&glink->idr_lock);
  		goto free_channel;
  	}
  	channel->rcid = ret;
  	mutex_unlock(&glink->idr_lock);
  
  	complete(&channel->open_req);
  
  	if (create_device) {
  		rpdev = kzalloc(sizeof(*rpdev), GFP_KERNEL);
  		if (!rpdev) {
  			ret = -ENOMEM;
  			goto rcid_remove;
  		}
  
  		rpdev->ept = &channel->ept;
  		strncpy(rpdev->id.name, name, RPMSG_NAME_SIZE);
  		rpdev->src = RPMSG_ADDR_ANY;
  		rpdev->dst = RPMSG_ADDR_ANY;
  		rpdev->ops = &glink_device_ops;
  
  		rpdev->dev.of_node = glink_rpm_match_channel(glink->dev->of_node, name);
  		rpdev->dev.parent = glink->dev;
  		rpdev->dev.release = glink_rpm_rpdev_release;
  
  		ret = rpmsg_register_device(rpdev);
  		if (ret)
  			goto free_rpdev;
  
  		channel->rpdev = rpdev;
  	}
  
  	return 0;
  
  free_rpdev:
  	kfree(rpdev);
  rcid_remove:
  	mutex_lock(&glink->idr_lock);
  	idr_remove(&glink->rcids, channel->rcid);
  	channel->rcid = 0;
  	mutex_unlock(&glink->idr_lock);
  free_channel:
  	/* Release the reference, iff we took it */
  	if (create_device)
  		kref_put(&channel->refcount, glink_rpm_channel_release);
  
  	return ret;
  }
  
  static void glink_rpm_rx_close(struct glink_rpm *glink, unsigned int rcid)
  {
  	struct rpmsg_channel_info chinfo;
  	struct glink_channel *channel;
  
  	channel = idr_find(&glink->rcids, rcid);
  	if (WARN(!channel, "close request on unknown channel\n"))
  		return;
  
  	if (channel->rpdev) {
  		strncpy(chinfo.name, channel->name, sizeof(chinfo.name));
  		chinfo.src = RPMSG_ADDR_ANY;
  		chinfo.dst = RPMSG_ADDR_ANY;
  
  		rpmsg_unregister_device(glink->dev, &chinfo);
  	}
  
  	glink_rpm_send_close_ack(glink, channel->rcid);
  
  	mutex_lock(&glink->idr_lock);
  	idr_remove(&glink->rcids, channel->rcid);
  	channel->rcid = 0;
  	mutex_unlock(&glink->idr_lock);
  
  	kref_put(&channel->refcount, glink_rpm_channel_release);
  }
  
  static void glink_rpm_rx_close_ack(struct glink_rpm *glink, unsigned int lcid)
  {
  	struct glink_channel *channel;
  
  	channel = idr_find(&glink->lcids, lcid);
  	if (WARN(!channel, "close ack on unknown channel\n"))
  		return;
  
  	mutex_lock(&glink->idr_lock);
  	idr_remove(&glink->lcids, channel->lcid);
  	channel->lcid = 0;
  	mutex_unlock(&glink->idr_lock);
  
  	kref_put(&channel->refcount, glink_rpm_channel_release);
  }
  
  static void glink_rpm_work(struct work_struct *work)
  {
  	struct glink_rpm *glink = container_of(work, struct glink_rpm, rx_work);
  	struct glink_defer_cmd *dcmd;
  	struct glink_msg *msg;
  	unsigned long flags;
  	unsigned int param1;
  	unsigned int param2;
  	unsigned int cmd;
  
  	for (;;) {
  		spin_lock_irqsave(&glink->rx_lock, flags);
  		if (list_empty(&glink->rx_queue)) {
  			spin_unlock_irqrestore(&glink->rx_lock, flags);
  			break;
  		}
  		dcmd = list_first_entry(&glink->rx_queue, struct glink_defer_cmd, node);
  		list_del(&dcmd->node);
  		spin_unlock_irqrestore(&glink->rx_lock, flags);
  
  		msg = &dcmd->msg;
  		cmd = le16_to_cpu(msg->cmd);
  		param1 = le16_to_cpu(msg->param1);
  		param2 = le32_to_cpu(msg->param2);
  
  		switch (cmd) {
  		case RPM_CMD_VERSION:
  			glink_rpm_send_version_ack(glink);
  			break;
  		case RPM_CMD_VERSION_ACK:
  			break;
  		case RPM_CMD_OPEN:
  			glink_rpm_rx_open(glink, param1, msg->data);
  			break;
  		case RPM_CMD_CLOSE:
  			glink_rpm_rx_close(glink, param1);
  			break;
  		case RPM_CMD_CLOSE_ACK:
  			glink_rpm_rx_close_ack(glink, param1);
  			break;
  		default:
  			WARN(1, "Unknown defer object %d\n", cmd);
  			break;
  		}
  
  		kfree(dcmd);
  	}
  }
  
  static int glink_rpm_parse_toc(struct device *dev,
  			       void __iomem *msg_ram,
  			       size_t msg_ram_size,
  			       struct glink_rpm_pipe *rx,
  			       struct glink_rpm_pipe *tx)
  {
  	struct rpm_toc *toc;
  	int num_entries;
  	unsigned int id;
  	size_t offset;
  	size_t size;
  	void *buf;
  	int i;
  
  	buf = kzalloc(RPM_TOC_SIZE, GFP_KERNEL);
  	if (!buf)
  		return -ENOMEM;
  
  	__ioread32_copy(buf, msg_ram + msg_ram_size - RPM_TOC_SIZE,
  			RPM_TOC_SIZE / sizeof(u32));
  
  	toc = buf;
  
  	if (le32_to_cpu(toc->magic) != RPM_TOC_MAGIC) {
  		dev_err(dev, "RPM TOC has invalid magic\n");
  		goto err_inval;
  	}
  
  	num_entries = le32_to_cpu(toc->count);
  	if (num_entries > RPM_TOC_MAX_ENTRIES) {
  		dev_err(dev, "Invalid number of toc entries\n");
  		goto err_inval;
  	}
  
  	for (i = 0; i < num_entries; i++) {
  		id = le32_to_cpu(toc->entries[i].id);
  		offset = le32_to_cpu(toc->entries[i].offset);
  		size = le32_to_cpu(toc->entries[i].size);
  
  		if (offset > msg_ram_size || offset + size > msg_ram_size) {
  			dev_err(dev, "TOC entry with invalid size\n");
  			continue;
  		}
  
  		switch (id) {
  		case RPM_RX_FIFO_ID:
  			rx->length = size;
  
  			rx->tail = msg_ram + offset;
  			rx->head = msg_ram + offset + sizeof(u32);
  			rx->fifo = msg_ram + offset + 2 * sizeof(u32);
  			break;
  		case RPM_TX_FIFO_ID:
  			tx->length = size;
  
  			tx->tail = msg_ram + offset;
  			tx->head = msg_ram + offset + sizeof(u32);
  			tx->fifo = msg_ram + offset + 2 * sizeof(u32);
  			break;
  		}
  	}
  
  	if (!rx->fifo || !tx->fifo) {
  		dev_err(dev, "Unable to find rx and tx descriptors\n");
  		goto err_inval;
  	}
  
  	kfree(buf);
  	return 0;
  
  err_inval:
  	kfree(buf);
  	return -EINVAL;
  }
  
  static int glink_rpm_probe(struct platform_device *pdev)
  {
  	struct glink_rpm *glink;
  	struct device_node *np;
  	void __iomem *msg_ram;
  	size_t msg_ram_size;
  	struct device *dev = &pdev->dev;
  	struct resource r;
  	int irq;
  	int ret;
  
  	glink = devm_kzalloc(dev, sizeof(*glink), GFP_KERNEL);
  	if (!glink)
  		return -ENOMEM;
  
  	glink->dev = dev;
  
  	mutex_init(&glink->tx_lock);
  	spin_lock_init(&glink->rx_lock);
  	INIT_LIST_HEAD(&glink->rx_queue);
  	INIT_WORK(&glink->rx_work, glink_rpm_work);
  
  	mutex_init(&glink->idr_lock);
  	idr_init(&glink->lcids);
  	idr_init(&glink->rcids);
  
  	glink->mbox_client.dev = &pdev->dev;
  	glink->mbox_chan = mbox_request_channel(&glink->mbox_client, 0);
  	if (IS_ERR(glink->mbox_chan)) {
  		if (PTR_ERR(glink->mbox_chan) != -EPROBE_DEFER)
  			dev_err(&pdev->dev, "failed to acquire IPC channel\n");
  		return PTR_ERR(glink->mbox_chan);
  	}
  
  	np = of_parse_phandle(dev->of_node, "qcom,rpm-msg-ram", 0);
  	ret = of_address_to_resource(np, 0, &r);
  	of_node_put(np);
  	if (ret)
  		return ret;
  
  	msg_ram = devm_ioremap(dev, r.start, resource_size(&r));
  	msg_ram_size = resource_size(&r);
  	if (!msg_ram)
  		return -ENOMEM;
  
  	ret = glink_rpm_parse_toc(dev, msg_ram, msg_ram_size,
  				  &glink->rx_pipe, &glink->tx_pipe);
  	if (ret)
  		return ret;
  
  	writel(0, glink->tx_pipe.head);
  	writel(0, glink->rx_pipe.tail);
  
  	irq = platform_get_irq(pdev, 0);
  	ret = devm_request_irq(dev, irq,
  			       glink_rpm_intr,
  			       IRQF_NO_SUSPEND | IRQF_SHARED,
  			       "glink-rpm", glink);
  	if (ret) {
  		dev_err(dev, "Failed to request IRQ\n");
  		return ret;
  	}
  
  	glink->irq = irq;
  
  	ret = glink_rpm_send_version(glink);
  	if (ret)
  		return ret;
  
  	platform_set_drvdata(pdev, glink);
  
  	return 0;
  }
  
  static int glink_rpm_remove_device(struct device *dev, void *data)
  {
  	device_unregister(dev);
  
  	return 0;
  }
  
  static int glink_rpm_remove(struct platform_device *pdev)
  {
  	struct glink_rpm *glink = platform_get_drvdata(pdev);
  	struct glink_channel *channel;
  	int cid;
  	int ret;
  
  	disable_irq(glink->irq);
  	cancel_work_sync(&glink->rx_work);
  
  	ret = device_for_each_child(glink->dev, NULL, glink_rpm_remove_device);
  	if (ret)
  		dev_warn(glink->dev, "Can't remove GLINK devices: %d\n", ret);
  
  	/* Release any defunct local channels, waiting for close-ack */
  	idr_for_each_entry(&glink->lcids, channel, cid)
  		kref_put(&channel->refcount, glink_rpm_channel_release);
  
  	idr_destroy(&glink->lcids);
  	idr_destroy(&glink->rcids);
  
  	return 0;
  }
  
  static const struct of_device_id glink_rpm_of_match[] = {
  	{ .compatible = "qcom,glink-rpm" },
  	{}
  };
  MODULE_DEVICE_TABLE(of, glink_rpm_of_match);
  
  static struct platform_driver glink_rpm_driver = {
  	.probe = glink_rpm_probe,
  	.remove = glink_rpm_remove,
  	.driver = {
  		.name = "qcom_glink_rpm",
  		.of_match_table = glink_rpm_of_match,
  	},
  };
  
  static int __init glink_rpm_init(void)
  {
  	return platform_driver_register(&glink_rpm_driver);
  }
  subsys_initcall(glink_rpm_init);
  
  static void __exit glink_rpm_exit(void)
  {
  	platform_driver_unregister(&glink_rpm_driver);
  }
  module_exit(glink_rpm_exit);
  
  MODULE_AUTHOR("Bjorn Andersson <bjorn.andersson@linaro.org>");
  MODULE_DESCRIPTION("Qualcomm GLINK RPM driver");
  MODULE_LICENSE("GPL v2");
  