drivers/soc/qcom/glink_bgcom_xprt.c

/* Copyright (c) 2017-2019, The Linux Foundation. All rights reserved.
 *
 * 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/delay.h>
#include <linux/err.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/srcu.h>
#include <linux/wait.h>
#include <linux/component.h>
#include <soc/qcom/tracer_pkt.h>

#include "glink_core_if.h"
#include "glink_private.h"
#include "glink_xprt_if.h"
#include "bgcom.h"

#define XPRT_NAME "bgcom"
#define FIFO_ALIGNMENT 16
#define TRACER_PKT_FEATURE BIT(2)
#define SHORT_PKT_SIZE 16
#define XPRT_ALIGNMENT 4

#define ACTIVE_TX BIT(0)
#define ACTIVE_RX BIT(1)

#define ID_MASK 0xFFFFFF

#define BGCOM_RESET 0x00000000
#define BGCOM_APPLICATION_RUNNING 0x00000001
#define BGCOM_TO_SLAVE_FIFO_READY 0x00000002
#define BGCOM_TO_MASTER_FIFO_READY 0x00000004
#define BGCOM_AHB_READY 0x00000008
#define WORD_SIZE 4
#define TX_BLOCKED_CMD_RESERVE 16
#define FIFO_FULL_RESERVE (TX_BLOCKED_CMD_RESERVE/WORD_SIZE)
#define BGCOM_LINKUP (BGCOM_APPLICATION_RUNNING \
			| BGCOM_TO_SLAVE_FIFO_READY \
			| BGCOM_TO_MASTER_FIFO_READY \
			| BGCOM_AHB_READY)
/**
 * enum command_types - definition of the types of commands sent/received
 * @VERSION_CMD:		Version and feature set supported
 * @VERSION_ACK_CMD:		Response for @VERSION_CMD
 * @OPEN_CMD:			Open a channel
 * @CLOSE_CMD:			Close a channel
 * @OPEN_ACK_CMD:		Response to @OPEN_CMD
 * @CLOSE_ACK_CMD:		Response for @CLOSE_CMD
 * @RX_INTENT_CMD:		RX intent for a channel is queued
 * @RX_DONE_CMD:		Use of RX intent for a channel is complete
 * @RX_DONE_W_REUSE_CMD:	Same as @RX_DONE but also reuse the used intent
 * @RX_INTENT_REQ_CMD:		Request to have RX intent queued
 * @RX_INTENT_REQ_ACK_CMD:	Response for @RX_INTENT_REQ_CMD
 * @TX_DATA_CMD:		Start of a data transfer
 * @TX_DATA_CONT_CMD:		Continuation or end of a data transfer
 * @READ_NOTIF_CMD:		Request for a notification when this cmd is read
 * @SIGNALS_CMD:		Sideband signals
 * @TRACER_PKT_CMD:		Start of a Tracer Packet Command
 * @TRACER_PKT_CONT_CMD:	Continuation or end of a Tracer Packet Command
 * @TX_SHORT_DATA_CMD:		Transmit short packets
 */
enum command_types {
	VERSION_CMD,
	VERSION_ACK_CMD,
	OPEN_CMD,
	CLOSE_CMD,
	OPEN_ACK_CMD,
	CLOSE_ACK_CMD,
	RX_INTENT_CMD,
	RX_DONE_CMD,
	RX_DONE_W_REUSE_CMD,
	RX_INTENT_REQ_CMD,
	RX_INTENT_REQ_ACK_CMD,
	TX_DATA_CMD,
	TX_DATA_CONT_CMD,
	READ_NOTIF_CMD,
	SIGNALS_CMD,
	TRACER_PKT_CMD,
	TRACER_PKT_CONT_CMD,
	TX_SHORT_DATA_CMD,
};

struct bgcom_fifo_size {
	uint32_t to_master:16;
	uint32_t to_slave:16;
};

struct bgcom_fifo_fill {
	uint32_t rx_avail:16;
	uint32_t tx_avail:16;
};

/**
 * struct edge_info - local information for managing a single complete edge
 * @list:			List item to traverse in edge_info list
 * @xprt_if:			The transport interface registered with the
 *				glink core associated with this edge.
 * @xprt_cfg:			The transport configuration for the glink core
 *				assocaited with this edge.
 * @subsys_name:		Name of the remote subsystem in the edge.
 * @bgcom_dev:			Pointer to the connectingSPI Device.
 * @fifo_size:			Size of the FIFO at the remote end.
 * @fifo_fill:			Current available fifo size.
 * @tx_avail_lock:		Lock to serialize access to tx_avail.
 * @kwork:			Work to be executed when receiving data.
 * @kworker:			Handle to the entity processing @kwork.
 * @task:			Handle to the task context that runs @kworker.
 * @use_ref:			Active users of this transport grab a
 *				reference. Used for SSR synchronization.
 * @in_ssr:			Signals if this transport is in ssr.
 * @water_mark_reached		Signals if tx_avail need to read from fifo.
 * @write_lock:			Lock to serialize write/tx operation.
 * @tx_blocked_queue:		Queue of entities waiting for the remote side to
 *				signal the resumption of TX.
 * @tx_resume_needed:		A tx resume signal needs to be sent to the glink
 *				core.
 * @tx_blocked_signal_sent:	Flag to indicate the flush signal has already
 *				been sent, and a response is pending from the
 *				remote side.  Protected by @write_lock.
 * @num_pw_states:		Size of @ramp_time_us.
 * @ramp_time_us:		Array of ramp times in microseconds where array
 *				index position represents a power state.
 * @bgcom_status		Maintains bgcom status based on events.
 * @wakeup_work	:		Work item for waking up tx_thread
 * @activity_flag:		Flag indicating active TX and RX.
 * @activity_lock:		Lock to synchronize access to activity flag.
 * @bgcom_config:		Config to be given to bgcom driver.
 * @bgcom_handle:		Handle to use bgcom driver apis.
 */
struct edge_info {
	struct list_head list;
	struct glink_transport_if xprt_if;
	struct glink_core_transport_cfg xprt_cfg;
	char subsys_name[GLINK_NAME_SIZE];
	struct bgcom_device *bgcom_dev;

	struct bgcom_fifo_size fifo_size;
	struct bgcom_fifo_fill fifo_fill;
	struct mutex tx_avail_lock;

	struct kthread_worker kworker;
	struct task_struct *task;
	struct srcu_struct use_ref;
	bool in_ssr;
	bool water_mark_reached;
	struct mutex write_lock;
	wait_queue_head_t tx_blocked_queue;
	bool tx_resume_needed;
	bool tx_blocked_signal_sent;

	uint32_t num_pw_states;
	unsigned long *ramp_time_us;
	uint32_t bgcom_status;
	struct work_struct wakeup_work;
	uint32_t activity_flag;
	spinlock_t activity_lock;
	struct bgcom_open_config_type bgcom_config;
	void *bgcom_handle;
};

struct rx_pkt {
	void *rx_buf;
	uint32_t rx_len;
	struct edge_info *einfo;
	struct kthread_work kwork;
};


static uint32_t negotiate_features_v1(struct glink_transport_if *if_ptr,
				      const struct glink_core_version *version,
				      uint32_t features);
static DEFINE_SPINLOCK(edge_infos_lock);
static LIST_HEAD(edge_infos);
static struct glink_core_version versions[] = {
	{1, TRACER_PKT_FEATURE, negotiate_features_v1},
};

/**
 * negotiate_features_v1() - determine what features of a version can be used
 * @if_ptr:	The transport for which features are negotiated for.
 * @version:	The version negotiated.
 * @features:	The set of requested features.
 *
 * Return: What set of the requested features can be supported.
 */
static uint32_t negotiate_features_v1(struct glink_transport_if *if_ptr,
				      const struct glink_core_version *version,
				      uint32_t features)
{
	return features & version->features;
}

/**
 * glink_bgcom_get_tx_avail() - Available Write Space in the remote side
 * @einfo:	Edge information corresponding to the remote side.
 *
 * Return: 0 on error, available write space on success.
 */
static int glink_bgcom_get_tx_avail(struct edge_info *einfo)
{
	uint32_t tx_avail;

	mutex_lock(&einfo->tx_avail_lock);
	tx_avail = einfo->fifo_fill.tx_avail;
	if (tx_avail < FIFO_FULL_RESERVE)
		tx_avail = 0;
	else
		tx_avail -= FIFO_FULL_RESERVE;

	mutex_unlock(&einfo->tx_avail_lock);
	return tx_avail;
}


/**
 * glink_bgcom_update_tx_avail() - update available Write Space in fifo
 * @einfo:	Edge information corresponding to the remote side.
 * @size:	size to update.
 *
 * Return: 0 on error, available write space on success.
 */
static void glink_bgcom_update_tx_avail(struct edge_info *einfo, uint32_t size)
{
	mutex_lock(&einfo->tx_avail_lock);
	einfo->fifo_fill.tx_avail -= size;
	if (einfo->fifo_fill.tx_avail < einfo->fifo_size.to_slave/2)
		einfo->water_mark_reached = true;
	mutex_unlock(&einfo->tx_avail_lock);
}

/**
 * glink_bgcom_xprt_tx_cmd_safe() - Transmit G-Link commands
 * @einfo:	Edge information corresponding to the remote subsystem.
 * @src:	Source buffer containing the G-Link command.
 * @size:	Size of the command to transmit.
 *
 * This function is used to transmit the G-Link commands. This function
 * must be called with einfo->write_lock locked.
 *
 * Return: 0 on success, standard Linux error codes on error.
 */
static int glink_bgcom_xprt_tx_cmd_safe(struct edge_info *einfo, void *src,
				      uint32_t size)
{
	uint32_t tx_avail = glink_bgcom_get_tx_avail(einfo);
	int ret;
	uint32_t size_in_words = size/WORD_SIZE;

	if (size_in_words > tx_avail) {
		GLINK_ERR("%s: No Space in Fifo\n", __func__);
		return -ENOSPC;
	}

	ret = bgcom_fifo_write(einfo->bgcom_handle, size_in_words, src);
	if (ret < 0) {
		GLINK_ERR("%s: Error %d writing data\n", __func__, ret);
		return ret;
	}
	glink_bgcom_update_tx_avail(einfo, size_in_words);
	return ret;
}

/**
 * send_tx_blocked_signal() - Send flow control request message
 * @einfo:	Edge information corresponding to the remote subsystem.
 *
 * This function is used to send a message to the remote subsystem indicating
 * that the local subsystem is waiting for the write space. The remote
 * subsystem on receiving this message will send a resume tx message.
 */
static void send_tx_blocked_signal(struct edge_info *einfo)
{
	struct read_notif_request {
		uint16_t cmd;
		uint16_t reserved;
		uint32_t reserved2;
		uint64_t reserved3;
	};
	struct read_notif_request read_notif_req = {0};
	int size_in_word = sizeof(read_notif_req)/WORD_SIZE;
	void *src = &read_notif_req;
	int ret;

	read_notif_req.cmd = READ_NOTIF_CMD;
	if (!einfo->tx_blocked_signal_sent) {
		einfo->tx_blocked_signal_sent = true;
		ret = bgcom_fifo_write(einfo->bgcom_handle, size_in_word, src);
		if (ret < 0) {
			GLINK_ERR("%s: Err %d send blocked\n", __func__, ret);
			return;
		}
		glink_bgcom_update_tx_avail(einfo, size_in_word);
	}
}

/**
 * glink_bgcom_xprt_tx_cmd() - Transmit G-Link commands
 * @einfo:	Edge information corresponding to the remote subsystem.
 * @src:	Source buffer containing the G-Link command.
 * @size:	Size of the command to transmit.
 *
 * This function is used to transmit the G-Link commands. This function
 * might sleep if the space is not available to transmit the command.
 *
 * Return: 0 on success, standard Linux error codes on error.
 */
static int glink_bgcom_xprt_tx_cmd(struct edge_info *einfo, void *src,
				 uint32_t size)
{
	int ret;
	DEFINE_WAIT_FUNC(wait, woken_wake_function);

	mutex_lock(&einfo->write_lock);
	add_wait_queue(&einfo->tx_blocked_queue, &wait);
	while (glink_bgcom_get_tx_avail(einfo) < (size/WORD_SIZE)) {
		send_tx_blocked_signal(einfo);
		if (einfo->in_ssr) {
			remove_wait_queue(&einfo->tx_blocked_queue, &wait);
			mutex_unlock(&einfo->write_lock);
			return -EFAULT;
		}
		mutex_unlock(&einfo->write_lock);
		wait_woken(&wait, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
		mutex_lock(&einfo->write_lock);
	}
	remove_wait_queue(&einfo->tx_blocked_queue, &wait);
	ret = glink_bgcom_xprt_tx_cmd_safe(einfo, src, size);
	mutex_unlock(&einfo->write_lock);
	return ret;
}

/**
 * process_rx_data() - process received data from an edge
 * @einfo:		The edge the data is received on.
 * @cmd_id:		ID to specify the type of data.
 * @rcid:		The remote channel id associated with the data.
 * @intend_id:		The intent the data should be put in.
 * @src:		Address of the source buffer from which the data
 *			is read.
 * @frag_size:		Size of the data fragment to read.
 * @size_remaining:	Size of data left to be read in this packet.
 */
static void process_rx_data(struct edge_info *einfo, uint16_t cmd_id,
			    uint32_t rcid, uint32_t intent_id, void *src,
			    uint32_t frag_size, uint32_t size_remaining)
{
	struct glink_core_rx_intent *intent;
	int rc = 0;

	intent = einfo->xprt_if.glink_core_if_ptr->rx_get_pkt_ctx(
				&einfo->xprt_if, rcid, intent_id);
	if (intent == NULL) {
		GLINK_ERR("%s: no intent for ch %d liid %d\n", __func__, rcid,
			  intent_id);
		return;
	} else if (intent->data == NULL) {
		GLINK_ERR("%s: intent for ch %d liid %d has no data buff\n",
			  __func__, rcid, intent_id);
		return;
	} else if (intent->intent_size - intent->write_offset < frag_size ||
		 intent->write_offset + size_remaining > intent->intent_size) {
		GLINK_ERR("%s: rx data size:%d and remaining:%d %s %d %s:%d\n",
			  __func__, frag_size, size_remaining,
			  "will overflow ch", rcid, "intent", intent_id);
		return;
	}


	if (cmd_id == TX_SHORT_DATA_CMD)
		memcpy(intent->data + intent->write_offset, src, frag_size);
	else
		rc = bgcom_ahb_read(einfo->bgcom_handle, (uint32_t)(size_t)src,
				ALIGN(frag_size, WORD_SIZE)/WORD_SIZE,
				intent->data + intent->write_offset);

	if (rc < 0) {
		GLINK_ERR("%s: Error %d receiving data %d:%d:%d:%d\n",
			  __func__, rc, rcid, intent_id, frag_size,
			  size_remaining);
		size_remaining += frag_size;
	} else {
		intent->write_offset += frag_size;
		intent->pkt_size += frag_size;

		if (unlikely((cmd_id == TRACER_PKT_CMD ||
			cmd_id == TRACER_PKT_CONT_CMD) && !size_remaining)) {
			tracer_pkt_log_event(intent->data, GLINK_XPRT_RX);
			intent->tracer_pkt = true;
		}
	}
	einfo->xprt_if.glink_core_if_ptr->rx_put_pkt_ctx(&einfo->xprt_if,
				rcid, intent, size_remaining ? false : true);
}

/**
 * process_rx_cmd() - Process incoming G-Link commands
 * @einfo:	Edge information corresponding to the remote subsystem.
 * @rx_data:	Buffer which contains the G-Link commands to be processed.
 * @rx_size:	Size of the buffer containing the series of G-Link commands.
 *
 * This function is used to parse and process a series of G-Link commands
 * received in a buffer.
 */
static void process_rx_cmd(struct edge_info *einfo,
			   void *rx_data, int rx_size)
{
	struct command {
		uint16_t id;
		uint16_t param1;
		uint32_t param2;
		uint32_t param3;
		uint32_t param4;
	};
	struct intent_desc {
		uint32_t size;
		uint32_t id;
		uint64_t addr;
	};
	struct rx_desc {
		uint32_t size;
		uint32_t size_left;
		uint64_t addr;
	};
	struct rx_short_data_desc {
		unsigned char data[SHORT_PKT_SIZE];
	};
	struct command *cmd;
	struct intent_desc *intents;
	struct rx_desc *rx_descp;
	struct rx_short_data_desc *rx_sd_descp;
	int offset = 0;
	int rcu_id;
	uint16_t rcid;
	uint16_t name_len;
	uint16_t prio;
	char *name;
	bool granted;
	int i;


	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return;
	}

	while (offset < rx_size) {
		cmd = (struct command *)(rx_data + offset);
		offset += sizeof(*cmd);
		switch (cmd->id) {
		case VERSION_CMD:
			einfo->xprt_if.glink_core_if_ptr->rx_cmd_version(
				&einfo->xprt_if, cmd->param1, cmd->param2);
			break;

		case VERSION_ACK_CMD:
			einfo->xprt_if.glink_core_if_ptr->rx_cmd_version_ack(
				&einfo->xprt_if, cmd->param1, cmd->param2);
			break;

		case OPEN_CMD:
			rcid = cmd->param1;
			name_len = (uint16_t)(cmd->param2 & 0xFFFF);
			prio = (uint16_t)((cmd->param2 & 0xFFFF0000) >> 16);
			name = (char *)(rx_data + offset);
			offset += ALIGN(name_len, FIFO_ALIGNMENT);
			einfo->xprt_if.glink_core_if_ptr->rx_cmd_ch_remote_open(
				&einfo->xprt_if, rcid, name, prio);
			break;

		case CLOSE_CMD:
			einfo->xprt_if.glink_core_if_ptr->
					rx_cmd_ch_remote_close(
						&einfo->xprt_if, cmd->param1);
			break;

		case OPEN_ACK_CMD:
			prio = (uint16_t)(cmd->param2 & 0xFFFF);
			einfo->xprt_if.glink_core_if_ptr->rx_cmd_ch_open_ack(
				&einfo->xprt_if, cmd->param1, prio);
			break;

		case CLOSE_ACK_CMD:
			einfo->xprt_if.glink_core_if_ptr->rx_cmd_ch_close_ack(
					&einfo->xprt_if, cmd->param1);
			break;

		case RX_INTENT_CMD:
			for (i = 0; i < cmd->param2; i++) {
				intents = (struct intent_desc *)
						(rx_data + offset);
				offset += sizeof(*intents);
				einfo->xprt_if.glink_core_if_ptr->
					rx_cmd_remote_rx_intent_put_cookie(
					&einfo->xprt_if, cmd->param1,
					intents->id, intents->size,
					(void *)(uintptr_t)(intents->addr));
			}
			break;

		case RX_DONE_CMD:
			einfo->xprt_if.glink_core_if_ptr->rx_cmd_tx_done(
				&einfo->xprt_if, cmd->param1, cmd->param2,
				false);
			break;

		case RX_INTENT_REQ_CMD:
			einfo->xprt_if.glink_core_if_ptr->
				rx_cmd_remote_rx_intent_req(
					&einfo->xprt_if, cmd->param1,
					cmd->param2);
			break;

		case RX_INTENT_REQ_ACK_CMD:
			granted = cmd->param2 == 1 ? true : false;
			einfo->xprt_if.glink_core_if_ptr->
				rx_cmd_rx_intent_req_ack(&einfo->xprt_if,
						cmd->param1, granted);
			break;

		case TX_DATA_CMD:
		case TX_DATA_CONT_CMD:
		case TRACER_PKT_CMD:
		case TRACER_PKT_CONT_CMD:
			rx_descp = (struct rx_desc *)(rx_data + offset);
			offset += sizeof(*rx_descp);
			process_rx_data(einfo, cmd->id, cmd->param1,
					cmd->param2,
					(void *)(uintptr_t)(rx_descp->addr),
					rx_descp->size, rx_descp->size_left);
			break;

		case TX_SHORT_DATA_CMD:
			rx_sd_descp = (struct rx_short_data_desc *)
							(rx_data + offset);
			offset += sizeof(*rx_sd_descp);
			process_rx_data(einfo, cmd->id, cmd->param1,
					cmd->param2, (void *)rx_sd_descp->data,
					cmd->param3, cmd->param4);
			break;

		case READ_NOTIF_CMD:
			break;

		case SIGNALS_CMD:
			einfo->xprt_if.glink_core_if_ptr->rx_cmd_remote_sigs(
				&einfo->xprt_if, cmd->param1, cmd->param2);
			break;

		case RX_DONE_W_REUSE_CMD:
			einfo->xprt_if.glink_core_if_ptr->rx_cmd_tx_done(
				&einfo->xprt_if, cmd->param1,
				cmd->param2, true);
			break;

		default:
			GLINK_ERR("Unrecognized command: %d\n", cmd->id);
			break;
		}
	}
	srcu_read_unlock(&einfo->use_ref, rcu_id);
}


/**
 * tx_wakeup_worker() - worker function to wakeup tx blocked thread
 * @work:	kwork associated with the edge to process commands on.
 */
static void tx_wakeup_worker(struct edge_info *einfo)
{
	int rcu_id;
	struct bgcom_fifo_fill fifo_fill;

	mutex_lock(&einfo->tx_avail_lock);
	bgcom_reg_read(einfo->bgcom_handle, BGCOM_REG_FIFO_FILL, 1,
						&fifo_fill);
	einfo->fifo_fill.tx_avail = fifo_fill.tx_avail;
	if (einfo->fifo_fill.tx_avail > einfo->fifo_size.to_slave/2)
		einfo->water_mark_reached = false;
	mutex_unlock(&einfo->tx_avail_lock);
	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return;
	}
	if (einfo->tx_resume_needed &&
				glink_bgcom_get_tx_avail(einfo)) {
		einfo->tx_resume_needed = false;
		einfo->xprt_if.glink_core_if_ptr->tx_resume(
						&einfo->xprt_if);
	}
	mutex_lock(&einfo->write_lock);
	if (einfo->tx_blocked_signal_sent) {
		wake_up_all(&einfo->tx_blocked_queue);
		einfo->tx_blocked_signal_sent = false;
	}
	mutex_unlock(&einfo->write_lock);
	srcu_read_unlock(&einfo->use_ref, rcu_id);
}

/**
 * __rx_worker() - Receive commands on a specific edge
 * @einfo:      Edge to process commands on.
 *
 * This function checks the size of data to be received, allocates the
 * buffer for that data and reads the data from the remote subsytem
 * into that buffer. This function then calls the process_rx_cmd() to
 * parse the received G-Link command sequence. This function will also
 * poll for the data for a predefined duration for performance reasons.
 */
static void __rx_worker(struct rx_pkt *rx_pkt_info)
{
	int rcu_id;
	struct edge_info *einfo = rx_pkt_info->einfo;

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return;
	}
	process_rx_cmd(einfo, rx_pkt_info->rx_buf,
				rx_pkt_info->rx_len*WORD_SIZE);
	kfree(rx_pkt_info->rx_buf);
	kfree(rx_pkt_info);
	srcu_read_unlock(&einfo->use_ref, rcu_id);
}

/**
 * rx_worker() - Worker function to process received commands
 * @work:       kwork associated with the edge to process commands on.
 */
static void rx_worker(struct kthread_work *work)
{
	struct rx_pkt *rx_pkt_info;

	rx_pkt_info = container_of(work, struct rx_pkt, kwork);
	__rx_worker(rx_pkt_info);
};

/**
 * tx_cmd_version() - Convert a version cmd to wire format and transmit
 * @if_ptr:     The transport to transmit on.
 * @version:    The version number to encode.
 * @features:   The features information to encode.
 */
static void tx_cmd_version(struct glink_transport_if *if_ptr, uint32_t version,
			   uint32_t features)
{
	struct command {
		uint16_t id;
		uint16_t version;
		uint32_t features;
		uint32_t fifo_size;
		uint32_t reserved;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return;
	}

	cmd.id = VERSION_CMD;
	cmd.version = version;
	cmd.features = features;

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));
	srcu_read_unlock(&einfo->use_ref, rcu_id);
}

/**
 * tx_cmd_version_ack() - Convert a version ack cmd to wire format and transmit
 * @if_ptr:	The transport to transmit on.
 * @version:	The version number to encode.
 * @features:	The features information to encode.
 */
static void tx_cmd_version_ack(struct glink_transport_if *if_ptr,
			       uint32_t version,
			       uint32_t features)
{
	struct command {
		uint16_t id;
		uint16_t version;
		uint32_t features;
		uint32_t fifo_size;
		uint32_t reserved;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return;
	}

	cmd.id = VERSION_ACK_CMD;
	cmd.version = version;
	cmd.features = features;

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));
	srcu_read_unlock(&einfo->use_ref, rcu_id);
}

/**
 * set_version() - Activate a negotiated version and feature set
 * @if_ptr:	The transport to configure.
 * @version:	The version to use.
 * @features:	The features to use.
 *
 * Return: The supported capabilities of the transport.
 */
static uint32_t set_version(struct glink_transport_if *if_ptr, uint32_t version,
			uint32_t features)
{
	struct edge_info *einfo;
	uint32_t ret;
	int rcu_id;

	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return 0;
	}

	ret = GCAP_SIGNALS;
	if (features & TRACER_PKT_FEATURE)
		ret |= GCAP_TRACER_PKT;

	srcu_read_unlock(&einfo->use_ref, rcu_id);
	return ret;
}

/**
 * tx_cmd_ch_open() - Convert a channel open cmd to wire format and transmit
 * @if_ptr:	The transport to transmit on.
 * @lcid:	The local channel id to encode.
 * @name:	The channel name to encode.
 * @req_xprt:	The transport the core would like to migrate this channel to.
 *
 * Return: 0 on success or standard Linux error code.
 */
static int tx_cmd_ch_open(struct glink_transport_if *if_ptr, uint32_t lcid,
			  const char *name, uint16_t req_xprt)
{
	struct command {
		uint16_t id;
		uint16_t lcid;
		uint16_t length;
		uint16_t req_xprt;
		uint64_t reserved;
	};
	struct command cmd;
	struct edge_info *einfo;
	uint32_t buf_size;
	void *buf;
	int rcu_id;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EFAULT;
	}

	cmd.id = OPEN_CMD;
	cmd.lcid = lcid;
	cmd.length = (uint16_t)(strlen(name) + 1);
	cmd.req_xprt = req_xprt;

	buf_size = ALIGN(sizeof(cmd) + cmd.length, FIFO_ALIGNMENT);

	buf = kzalloc(buf_size, GFP_KERNEL);
	if (!buf) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -ENOMEM;
	}

	memcpy(buf, &cmd, sizeof(cmd));
	memcpy(buf + sizeof(cmd), name, cmd.length);

	glink_bgcom_xprt_tx_cmd(einfo, buf, buf_size);

	kfree(buf);
	srcu_read_unlock(&einfo->use_ref, rcu_id);
	return 0;
}

/**
 * tx_cmd_ch_close() - Convert a channel close cmd to wire format and transmit
 * @if_ptr:	The transport to transmit on.
 * @lcid:	The local channel id to encode.
 *
 * Return: 0 on success or standard Linux error code.
 */
static int tx_cmd_ch_close(struct glink_transport_if *if_ptr, uint32_t lcid)
{
	struct command {
		uint16_t id;
		uint16_t lcid;
		uint32_t reserved1;
		uint64_t reserved2;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EFAULT;
	}

	cmd.id = CLOSE_CMD;
	cmd.lcid = lcid;

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));

	srcu_read_unlock(&einfo->use_ref, rcu_id);
	return 0;
}

/**
 * tx_cmd_ch_remote_open_ack() - Convert a channel open ack cmd to wire format
 *				 and transmit
 * @if_ptr:	The transport to transmit on.
 * @rcid:	The remote channel id to encode.
 * @xprt_resp:	The response to a transport migration request.
 */
static void tx_cmd_ch_remote_open_ack(struct glink_transport_if *if_ptr,
				     uint32_t rcid, uint16_t xprt_resp)
{
	struct command {
		uint16_t id;
		uint16_t rcid;
		uint16_t reserved1;
		uint16_t xprt_resp;
		uint64_t reserved2;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return;
	}

	cmd.id = OPEN_ACK_CMD;
	cmd.rcid = rcid;
	cmd.xprt_resp = xprt_resp;

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));
	srcu_read_unlock(&einfo->use_ref, rcu_id);
}

/**
 * tx_cmd_ch_remote_close_ack() - Convert a channel close ack cmd to wire format
 *				  and transmit
 * @if_ptr:	The transport to transmit on.
 * @rcid:	The remote channel id to encode.
 */
static void tx_cmd_ch_remote_close_ack(struct glink_transport_if *if_ptr,
				       uint32_t rcid)
{
	struct command {
		uint16_t id;
		uint16_t rcid;
		uint32_t reserved1;
		uint64_t reserved2;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return;
	}

	cmd.id = CLOSE_ACK_CMD;
	cmd.rcid = rcid;

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));
	srcu_read_unlock(&einfo->use_ref, rcu_id);
}

/**
 * ssr() - Process a subsystem restart notification of a transport
 * @if_ptr:	The transport to restart
 *
 * Return: 0 on success or standard Linux error code.
 */
static int ssr(struct glink_transport_if *if_ptr)
{
	struct edge_info *einfo;

	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	einfo->in_ssr = true;
	wake_up_all(&einfo->tx_blocked_queue);

	synchronize_srcu(&einfo->use_ref);
	einfo->tx_resume_needed = false;
	einfo->tx_blocked_signal_sent = false;
	einfo->xprt_if.glink_core_if_ptr->link_down(&einfo->xprt_if);

	return 0;
}

/**
 * allocate_rx_intent() - Allocate/reserve space for RX Intent
 * @if_ptr:	The transport the intent is associated with.
 * @size:	size of intent.
 * @intent:	Pointer to the intent structure.
 *
 * Assign "data" with the buffer created, since the transport creates
 * a linear buffer and "iovec" with the "intent" itself, so that
 * the data can be passed to a client that receives only vector buffer.
 * Note that returning NULL for the pointer is valid (it means that space has
 * been reserved, but the actual pointer will be provided later).
 *
 * Return: 0 on success or standard Linux error code.
 */
static int allocate_rx_intent(struct glink_transport_if *if_ptr, size_t size,
			      struct glink_core_rx_intent *intent)
{
	void *t;

	t = kzalloc(ALIGN(size, WORD_SIZE), GFP_KERNEL);
	if (!t)
		return -ENOMEM;

	intent->data = t;
	intent->iovec = (void *)intent;
	intent->vprovider = rx_linear_vbuf_provider;
	intent->pprovider = NULL;
	return 0;
}

/**
 * deallocate_rx_intent() - Deallocate space created for RX Intent
 * @if_ptr:	The transport the intent is associated with.
 * @intent:	Pointer to the intent structure.
 *
 * Return: 0 on success or standard Linux error code.
 */
static int deallocate_rx_intent(struct glink_transport_if *if_ptr,
				struct glink_core_rx_intent *intent)
{
	if (!intent || !intent->data)
		return -EINVAL;

	kfree(intent->data);
	intent->data = NULL;
	intent->iovec = NULL;
	intent->vprovider = NULL;
	return 0;
}

/**
 * tx_cmd_local_rx_intent() - Convert an rx intent cmd to wire format and
 *			      transmit
 * @if_ptr:	The transport to transmit on.
 * @lcid:	The local channel id to encode.
 * @size:	The intent size to encode.
 * @liid:	The local intent id to encode.
 *
 * Return: 0 on success or standard Linux error code.
 */
static int tx_cmd_local_rx_intent(struct glink_transport_if *if_ptr,
				  uint32_t lcid, size_t size, uint32_t liid)
{
	struct command {
		uint16_t id;
		uint16_t lcid;
		uint32_t count;
		uint64_t reserved;
		uint32_t size;
		uint32_t liid;
		uint64_t addr;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	if (size > UINT_MAX) {
		GLINK_ERR("%s: size %zu is too large to encode\n",
							__func__, size);
		return -EMSGSIZE;
	}

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EFAULT;
	}

	cmd.id = RX_INTENT_CMD;
	cmd.lcid = lcid;
	cmd.count = 1;
	cmd.size = size;
	cmd.liid = liid;

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));

	srcu_read_unlock(&einfo->use_ref, rcu_id);
	return 0;
}

/**
 * tx_cmd_local_rx_done() - Convert an rx done cmd to wire format and transmit
 * @if_ptr:	The transport to transmit on.
 * @lcid:	The local channel id to encode.
 * @liid:	The local intent id to encode.
 * @reuse:	Reuse the consumed intent.
 */
static void tx_cmd_local_rx_done(struct glink_transport_if *if_ptr,
				 uint32_t lcid, uint32_t liid, bool reuse)
{
	struct command {
		uint16_t id;
		uint16_t lcid;
		uint32_t liid;
		uint64_t reserved;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return;
	}

	cmd.id = reuse ? RX_DONE_W_REUSE_CMD : RX_DONE_CMD;
	cmd.lcid = lcid;
	cmd.liid = liid;

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));
	srcu_read_unlock(&einfo->use_ref, rcu_id);
}

/**
 * tx_cmd_rx_intent_req() - Convert an rx intent request cmd to wire format and
 *			    transmit
 * @if_ptr:	The transport to transmit on.
 * @lcid:	The local channel id to encode.
 * @size:	The requested intent size to encode.
 *
 * Return: 0 on success or standard Linux error code.
 */
static int tx_cmd_rx_intent_req(struct glink_transport_if *if_ptr,
				uint32_t lcid, size_t size)
{
	struct command {
		uint16_t id;
		uint16_t lcid;
		uint32_t size;
		uint64_t reserved;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	if (size > UINT_MAX) {
		GLINK_ERR("%s: size %zu is too large to encode\n",
							__func__, size);
		return -EMSGSIZE;
	}

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EFAULT;
	}

	cmd.id = RX_INTENT_REQ_CMD,
	cmd.lcid = lcid;
	cmd.size = ALIGN(size, WORD_SIZE);

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));

	srcu_read_unlock(&einfo->use_ref, rcu_id);
	return 0;
}

/**
 * tx_cmd_rx_intent_req_ack() - Convert an rx intent request ack cmd to wire
 *				format and transmit
 * @if_ptr:	The transport to transmit on.
 * @lcid:	The local channel id to encode.
 * @granted:	The request response to encode.
 *
 * Return: 0 on success or standard Linux error code.
 */
static int tx_cmd_remote_rx_intent_req_ack(struct glink_transport_if *if_ptr,
					   uint32_t lcid, bool granted)
{
	struct command {
		uint16_t id;
		uint16_t lcid;
		uint32_t response;
		uint64_t reserved;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EFAULT;
	}

	cmd.id = RX_INTENT_REQ_ACK_CMD,
	cmd.lcid = lcid;
	if (granted)
		cmd.response = 1;
	else
		cmd.response = 0;

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));

	srcu_read_unlock(&einfo->use_ref, rcu_id);
	return 0;
}

/**
 * tx_cmd_set_sigs() - Convert a signals ack cmd to wire format and transmit
 * @if_ptr:	The transport to transmit on.
 * @lcid:	The local channel id to encode.
 * @sigs:	The signals to encode.
 *
 * Return: 0 on success or standard Linux error code.
 */
static int tx_cmd_set_sigs(struct glink_transport_if *if_ptr, uint32_t lcid,
			   uint32_t sigs)
{
	struct command {
		uint16_t id;
		uint16_t lcid;
		uint32_t sigs;
		uint64_t reserved;
	};
	struct command cmd;
	struct edge_info *einfo;
	int rcu_id;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EFAULT;
	}

	cmd.id = SIGNALS_CMD,
	cmd.lcid = lcid;
	cmd.sigs = sigs;

	glink_bgcom_xprt_tx_cmd(einfo, &cmd, sizeof(cmd));

	srcu_read_unlock(&einfo->use_ref, rcu_id);
	return 0;
}

/**
 * tx_data() - convert a data/tracer_pkt to wire format and transmit
 * @if_ptr:     The transport to transmit on.
 * @cmd_id:     The command ID to transmit.
 * @lcid:       The local channel id to encode.
 * @pctx:       The data to encode.
 *
 * Return: Number of bytes written or standard Linux error code.
 */
static int tx_data(struct glink_transport_if *if_ptr, uint16_t cmd_id,
		   uint32_t lcid, struct glink_core_tx_pkt *pctx)
{
	struct command {
		uint16_t id;
		uint16_t lcid;
		uint32_t riid;
		uint64_t reserved;
		uint32_t size;
		uint32_t size_left;
		uint64_t addr;
	};
	struct command cmd;
	struct edge_info *einfo;
	void *data_start, *dst = NULL;
	size_t tx_size = 0;
	int rcu_id;

	if (pctx->size < pctx->size_remaining) {
		GLINK_ERR("%s: size remaining exceeds size.  Resetting.\n",
			  __func__);
		pctx->size_remaining = pctx->size;
	}
	if (!pctx->size_remaining)
		return 0;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EFAULT;
	}

	if (cmd_id == TX_DATA_CMD) {
		if (pctx->size_remaining == pctx->size)
			cmd.id = TX_DATA_CMD;
		else
			cmd.id = TX_DATA_CONT_CMD;
	} else {
		if (pctx->size_remaining == pctx->size)
			cmd.id = TRACER_PKT_CMD;
		else
			cmd.id = TRACER_PKT_CONT_CMD;
	}
	cmd.lcid = lcid;
	cmd.riid = pctx->riid;
	data_start = get_tx_vaddr(pctx, pctx->size - pctx->size_remaining,
				  &tx_size);
	if (unlikely(!data_start)) {
		GLINK_ERR("%s: invalid data_start\n", __func__);
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EINVAL;
	}
	if (tx_size & (XPRT_ALIGNMENT - 1))
		tx_size = ALIGN(tx_size - SHORT_PKT_SIZE, XPRT_ALIGNMENT);
	if (likely(pctx->cookie))
		dst = pctx->cookie + (pctx->size - pctx->size_remaining);

	mutex_lock(&einfo->write_lock);
	/* Need enough space to write the command */
	if (glink_bgcom_get_tx_avail(einfo) <= sizeof(cmd)/WORD_SIZE) {
		einfo->tx_resume_needed = true;
		send_tx_blocked_signal(einfo);
		mutex_unlock(&einfo->write_lock);
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		GLINK_ERR("%s: No Space in Fifo\n", __func__);
		return -EAGAIN;
	}
	cmd.addr = 0;
	cmd.size = tx_size;
	pctx->size_remaining -= tx_size;
	cmd.size_left = pctx->size_remaining;
	if (cmd.id == TRACER_PKT_CMD)
		tracer_pkt_log_event((void *)(pctx->data), GLINK_XPRT_TX);

	bgcom_resume(einfo->bgcom_handle);
	bgcom_ahb_write(einfo->bgcom_handle, (uint32_t)(size_t)dst,
				ALIGN(tx_size, WORD_SIZE)/WORD_SIZE,
				data_start);
	glink_bgcom_xprt_tx_cmd_safe(einfo, &cmd, sizeof(cmd));
	GLINK_DBG("%s %s: lcid[%u] riid[%u] cmd %d, size[%d], size_left[%d]\n",
		  "<BGCOM>", __func__, cmd.lcid, cmd.riid, cmd.id, cmd.size,
		  cmd.size_left);
	mutex_unlock(&einfo->write_lock);
	srcu_read_unlock(&einfo->use_ref, rcu_id);
	return cmd.size;
}

/**
 * tx_short_data() - Tansmit a short packet in band along with command
 * @if_ptr:     The transport to transmit on.
 * @cmd_id:     The command ID to transmit.
 * @lcid:       The local channel id to encode.
 * @pctx:       The data to encode.
 *
 * Return: Number of bytes written or standard Linux error code.
 */
static int tx_short_data(struct glink_transport_if *if_ptr,
			 uint32_t lcid, struct glink_core_tx_pkt *pctx)
{
	struct command {
		uint16_t id;
		uint16_t lcid;
		uint32_t riid;
		uint32_t size;
		uint32_t size_left;
		unsigned char data[SHORT_PKT_SIZE];
	};
	struct command cmd;
	struct edge_info *einfo;
	void *data_start;
	size_t tx_size = 0;
	int rcu_id;

	if (pctx->size < pctx->size_remaining) {
		GLINK_ERR("%s: size remaining exceeds size.  Resetting.\n",
			  __func__);
		pctx->size_remaining = pctx->size;
	}
	if (!pctx->size_remaining)
		return 0;

	memset(&cmd, 0, sizeof(cmd));
	einfo = container_of(if_ptr, struct edge_info, xprt_if);

	rcu_id = srcu_read_lock(&einfo->use_ref);
	if (einfo->in_ssr) {
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EFAULT;
	}

	cmd.id = TX_SHORT_DATA_CMD;
	cmd.lcid = lcid;
	cmd.riid = pctx->riid;
	data_start = get_tx_vaddr(pctx, pctx->size - pctx->size_remaining,
				  &tx_size);
	if (unlikely(!data_start || tx_size > SHORT_PKT_SIZE)) {
		GLINK_ERR("%s: invalid data_start %pK or tx_size %zu\n",
			  __func__, data_start, tx_size);
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EINVAL;
	}

	mutex_lock(&einfo->write_lock);
	if (glink_bgcom_get_tx_avail(einfo) <= sizeof(cmd)/WORD_SIZE) {
		einfo->tx_resume_needed = true;
		send_tx_blocked_signal(einfo);
		mutex_unlock(&einfo->write_lock);
		srcu_read_unlock(&einfo->use_ref, rcu_id);
		return -EAGAIN;
	}
	cmd.size = tx_size;
	pctx->size_remaining -= tx_size;
	cmd.size_left = pctx->size_remaining;
	memcpy(cmd.data, data_start, tx_size);
	bgcom_resume(einfo->bgcom_handle);
	glink_bgcom_xprt_tx_cmd_safe(einfo, &cmd, sizeof(cmd));
	GLINK_DBG("%s %s: lcid[%u] riid[%u] cmd[%d], size[%d], size_left[%d]\n",
		  "<SPI>", __func__, cmd.lcid, cmd.riid, cmd.id, cmd.size,
		  cmd.size_left);
	mutex_unlock(&einfo->write_lock);
	srcu_read_unlock(&einfo->use_ref, rcu_id);
	return cmd.size;
}

/**
 * tx() - convert a data transmit cmd to wire format and transmit
 * @if_ptr:     The transport to transmit on.
 * @lcid:       The local channel id to encode.
 * @pctx:       The data to encode.
 *
 * Return: Number of bytes written or standard Linux error code.
 */
static int tx(struct glink_transport_if *if_ptr, uint32_t lcid,
	      struct glink_core_tx_pkt *pctx)
{
	if (pctx->size_remaining <= SHORT_PKT_SIZE)
		return tx_short_data(if_ptr, lcid, pctx);
	return tx_data(if_ptr, TX_DATA_CMD, lcid, pctx);
}

/**
 * tx_cmd_tracer_pkt() - convert a tracer packet cmd to wire format and transmit
 * @if_ptr:     The transport to transmit on.
 * @lcid:       The local channel id to encode.
 * @pctx:       The data to encode.
 *
 * Return: Number of bytes written or standard Linux error code.
 */
static int tx_cmd_tracer_pkt(struct glink_transport_if *if_ptr, uint32_t lcid,
			     struct glink_core_tx_pkt *pctx)
{
	return tx_data(if_ptr, TRACER_PKT_CMD, lcid, pctx);
}

/**
 * int wait_link_down() - Check status of read/write indices
 * @if_ptr:     The transport to check
 *
 * Return: 1 if indices are all zero, 0 otherwise
 */
static int wait_link_down(struct glink_transport_if *if_ptr)
{
	return 0;
}

/**
 * get_power_vote_ramp_time() - Get the ramp time required for the power
 *                              votes to be applied
 * @if_ptr:     The transport interface on which power voting is requested.
 * @state:      The power state for which ramp time is required.
 *
 * Return: The ramp time specific to the power state, standard error otherwise.
 */
static unsigned long get_power_vote_ramp_time(
		struct glink_transport_if *if_ptr, uint32_t state)
{
	return 0;
}

/**
 * power_vote() - Update the power votes to meet qos requirement
 * @if_ptr:     The transport interface on which power voting is requested.
 * @state:      The power state for which the voting should be done.
 *
 * Return: 0 on Success, standard error otherwise.
 */
static int power_vote(struct glink_transport_if *if_ptr, uint32_t state)
{
	unsigned long flags;
	struct edge_info *einfo;

	einfo = container_of(if_ptr, struct edge_info, xprt_if);
	spin_lock_irqsave(&einfo->activity_lock, flags);
	einfo->activity_flag |= ACTIVE_TX;
	spin_unlock_irqrestore(&einfo->activity_lock, flags);
	return 0;
}

/**
 * power_unvote() - Remove the all the power votes
 * @if_ptr:     The transport interface on which power voting is requested.
 *
 * Return: 0 on Success, standard error otherwise.
 */
static int power_unvote(struct glink_transport_if *if_ptr)
{
	unsigned long flags;
	struct edge_info *einfo;

	einfo = container_of(if_ptr, struct edge_info, xprt_if);
	spin_lock_irqsave(&einfo->activity_lock, flags);
	einfo->activity_flag &= ~ACTIVE_TX;
	spin_unlock_irqrestore(&einfo->activity_lock, flags);
	return 0;
}

static void glink_bgcom_linkup(struct edge_info *einfo)
{
	if (einfo->bgcom_status != BGCOM_LINKUP)
		return;
	einfo->in_ssr = false;
	synchronize_srcu(&einfo->use_ref);
	bgcom_reg_read(einfo->bgcom_handle, BGCOM_REG_FIFO_SIZE, 1,
				&einfo->fifo_size);
	mutex_lock(&einfo->tx_avail_lock);
	einfo->fifo_fill.tx_avail = einfo->fifo_size.to_master;
	mutex_unlock(&einfo->tx_avail_lock);
	einfo->xprt_if.glink_core_if_ptr->link_up(&einfo->xprt_if);
}

static void glink_bgcom_event_handler(void *handle,
		void *priv_data, enum bgcom_event_type event,
		union bgcom_event_data_type *data)
{
	struct edge_info *einfo = (struct edge_info *)priv_data;
	struct rx_pkt *rx_pkt_info;

	switch (event) {
	case BGCOM_EVENT_APPLICATION_RUNNING:
		if (data->application_running &&
				einfo->bgcom_status != BGCOM_LINKUP) {
			einfo->bgcom_status |= BGCOM_APPLICATION_RUNNING;
			glink_bgcom_linkup(einfo);
		}
		break;
	case BGCOM_EVENT_TO_SLAVE_FIFO_READY:
		if (data->to_slave_fifo_ready &&
				einfo->bgcom_status != BGCOM_LINKUP) {
			einfo->bgcom_status |= BGCOM_TO_SLAVE_FIFO_READY;
			glink_bgcom_linkup(einfo);
		}
		break;
	case BGCOM_EVENT_TO_MASTER_FIFO_READY:
		if (data->to_master_fifo_ready &&
				einfo->bgcom_status != BGCOM_LINKUP) {
			einfo->bgcom_status |= BGCOM_TO_MASTER_FIFO_READY;
			glink_bgcom_linkup(einfo);
		}
		break;
	case BGCOM_EVENT_AHB_READY:
		if (data->ahb_ready &&
				einfo->bgcom_status != BGCOM_LINKUP) {
			einfo->bgcom_status |= BGCOM_AHB_READY;
			glink_bgcom_linkup(einfo);
		}
		break;
	case BGCOM_EVENT_TO_MASTER_FIFO_USED:
		rx_pkt_info = kzalloc(sizeof(struct rx_pkt), GFP_KERNEL);
		rx_pkt_info->rx_buf = data->fifo_data.data;
		rx_pkt_info->rx_len = data->fifo_data.to_master_fifo_used;
		rx_pkt_info->einfo = einfo;
		kthread_init_work(&rx_pkt_info->kwork, rx_worker);
		kthread_queue_work(&einfo->kworker, &rx_pkt_info->kwork);
		break;
	case BGCOM_EVENT_TO_SLAVE_FIFO_FREE:
		if (einfo->water_mark_reached)
			tx_wakeup_worker(einfo);
		break;
	case BGCOM_EVENT_RESET_OCCURRED:
		einfo->bgcom_status = BGCOM_RESET;
		ssr(&einfo->xprt_if);
		break;
	case BGCOM_EVENT_ERROR_WRITE_FIFO_OVERRUN:
	case BGCOM_EVENT_ERROR_WRITE_FIFO_BUS_ERR:
	case BGCOM_EVENT_ERROR_WRITE_FIFO_ACCESS:
	case BGCOM_EVENT_ERROR_READ_FIFO_UNDERRUN:
	case BGCOM_EVENT_ERROR_READ_FIFO_BUS_ERR:
	case BGCOM_EVENT_ERROR_READ_FIFO_ACCESS:
	case BGCOM_EVENT_ERROR_TRUNCATED_READ:
	case BGCOM_EVENT_ERROR_TRUNCATED_WRITE:
	case BGCOM_EVENT_ERROR_AHB_ILLEGAL_ADDRESS:
	case BGCOM_EVENT_ERROR_AHB_BUS_ERR:
		GLINK_ERR("%s: ERROR %d", __func__, event);
		break;
	default:
		GLINK_ERR("%s: unhandled event %d", __func__, event);
		break;
	}
}

/**
 * init_xprt_if() - Initialize the xprt_if for an edge
 * @einfo:	The edge to initialize.
 */
static void init_xprt_if(struct edge_info *einfo)
{
	einfo->xprt_if.tx_cmd_version = tx_cmd_version;
	einfo->xprt_if.tx_cmd_version_ack = tx_cmd_version_ack;
	einfo->xprt_if.set_version = set_version;
	einfo->xprt_if.tx_cmd_ch_open = tx_cmd_ch_open;
	einfo->xprt_if.tx_cmd_ch_close = tx_cmd_ch_close;
	einfo->xprt_if.tx_cmd_ch_remote_open_ack = tx_cmd_ch_remote_open_ack;
	einfo->xprt_if.tx_cmd_ch_remote_close_ack = tx_cmd_ch_remote_close_ack;
	einfo->xprt_if.ssr = ssr;
	einfo->xprt_if.allocate_rx_intent = allocate_rx_intent;
	einfo->xprt_if.deallocate_rx_intent = deallocate_rx_intent;
	einfo->xprt_if.tx_cmd_local_rx_intent = tx_cmd_local_rx_intent;
	einfo->xprt_if.tx_cmd_local_rx_done = tx_cmd_local_rx_done;
	einfo->xprt_if.tx = tx;
	einfo->xprt_if.tx_cmd_rx_intent_req = tx_cmd_rx_intent_req;
	einfo->xprt_if.tx_cmd_remote_rx_intent_req_ack =
						tx_cmd_remote_rx_intent_req_ack;
	einfo->xprt_if.tx_cmd_set_sigs = tx_cmd_set_sigs;
	einfo->xprt_if.wait_link_down = wait_link_down;
	einfo->xprt_if.tx_cmd_tracer_pkt = tx_cmd_tracer_pkt;
	einfo->xprt_if.get_power_vote_ramp_time = get_power_vote_ramp_time;
	einfo->xprt_if.power_vote = power_vote;
	einfo->xprt_if.power_unvote = power_unvote;
}

/**
 * init_xprt_cfg() - Initialize the xprt_cfg for an edge
 * @einfo:	The edge to initialize.
 * @name:	The name of the remote side this edge communicates to.
 */
static void init_xprt_cfg(struct edge_info *einfo, const char *name)
{
	einfo->xprt_cfg.name = XPRT_NAME;
	einfo->xprt_cfg.edge = name;
	einfo->xprt_cfg.versions = versions;
	einfo->xprt_cfg.versions_entries = ARRAY_SIZE(versions);
	einfo->xprt_cfg.max_cid = SZ_64K;
	einfo->xprt_cfg.max_iid = SZ_2G;
}

/**
 * parse_qos_dt_params() - Parse the power states from DT
 * @dev:	Reference to the platform device for a specific edge.
 * @einfo:	Edge information for the edge probe function is called.
 *
 * Return: 0 on success, standard error code otherwise.
 */
static int parse_qos_dt_params(struct device_node *node,
				struct edge_info *einfo)
{
	int rc;
	int i;
	char *key;
	uint32_t *arr32;
	uint32_t num_states;

	key = "qcom,ramp-time";
	if (!of_find_property(node, key, &num_states))
		return -ENODEV;

	num_states /= sizeof(uint32_t);

	einfo->num_pw_states = num_states;

	arr32 = kmalloc_array(num_states, sizeof(uint32_t), GFP_KERNEL);
	if (!arr32)
		return -ENOMEM;

	einfo->ramp_time_us = kmalloc_array(num_states, sizeof(unsigned long),
					GFP_KERNEL);
	if (!einfo->ramp_time_us) {
		rc = -ENOMEM;
		goto mem_alloc_fail;
	}

	rc = of_property_read_u32_array(node, key, arr32, num_states);
	if (rc) {
		rc = -ENODEV;
		goto invalid_key;
	}
	for (i = 0; i < num_states; i++)
		einfo->ramp_time_us[i] = arr32[i];

	kfree(arr32);
	return 0;

invalid_key:
	kfree(einfo->ramp_time_us);
mem_alloc_fail:
	kfree(arr32);
	return rc;
}

static int glink_bgcom_probe(struct platform_device *pdev)
{
	struct device_node *node;
	struct device_node *phandle_node;
	struct edge_info *einfo;
	int rc;
	char *key;
	const char *subsys_name;
	unsigned long flags;

	node = pdev->dev.of_node;

	einfo = devm_kzalloc(&pdev->dev, sizeof(*einfo), GFP_KERNEL);
	if (!einfo) {
		rc = -ENOMEM;
		goto edge_info_alloc_fail;
	}

	key = "label";
	subsys_name = of_get_property(node, key, NULL);
	if (!subsys_name) {
		GLINK_ERR("%s: missing key %s\n", __func__, key);
		rc = -ENODEV;
		goto missing_key;
	}
	strlcpy(einfo->subsys_name, subsys_name, sizeof(einfo->subsys_name));

	init_xprt_cfg(einfo, subsys_name);
	init_xprt_if(einfo);

	kthread_init_worker(&einfo->kworker);
	init_srcu_struct(&einfo->use_ref);
	mutex_init(&einfo->write_lock);
	init_waitqueue_head(&einfo->tx_blocked_queue);
	spin_lock_init(&einfo->activity_lock);
	mutex_init(&einfo->tx_avail_lock);

	spin_lock_irqsave(&edge_infos_lock, flags);
	list_add_tail(&einfo->list, &edge_infos);
	spin_unlock_irqrestore(&edge_infos_lock, flags);

	einfo->task = kthread_run(kthread_worker_fn, &einfo->kworker,
				  "bgcom_%s", subsys_name);
	if (IS_ERR(einfo->task)) {
		rc = PTR_ERR(einfo->task);
		GLINK_ERR("%s: kthread run failed %d\n", __func__, rc);
		goto kthread_fail;
	}

	key = "qcom,qos-config";
	phandle_node = of_parse_phandle(node, key, 0);
	if (phandle_node && !(of_get_glink_core_qos_cfg(phandle_node,
							&einfo->xprt_cfg)))
		parse_qos_dt_params(node, einfo);

	rc = glink_core_register_transport(&einfo->xprt_if, &einfo->xprt_cfg);
	if (rc == -EPROBE_DEFER)
		goto reg_xprt_fail;
	if (rc) {
		GLINK_ERR("%s: glink core register transport failed: %d\n",
			__func__, rc);
		goto reg_xprt_fail;
	}

	einfo->bgcom_config.priv = (void *)einfo;
	einfo->bgcom_config.bgcom_notification_cb = glink_bgcom_event_handler;
	einfo->bgcom_handle = NULL;
	dev_set_drvdata(&pdev->dev, einfo);
	if (!strcmp(einfo->xprt_cfg.edge, "bg")) {
		einfo->bgcom_handle = bgcom_open(&einfo->bgcom_config);
		if (!einfo->bgcom_handle) {
			GLINK_ERR("%s: bgcom open failed\n", __func__);
			rc = -ENODEV;
			goto bgcom_open_fail;
		}
	}
	return 0;

bgcom_open_fail:
	dev_set_drvdata(&pdev->dev, NULL);
	glink_core_unregister_transport(&einfo->xprt_if);
reg_xprt_fail:
	kthread_flush_worker(&einfo->kworker);
	kthread_stop(einfo->task);
	einfo->task = NULL;
kthread_fail:
	spin_lock_irqsave(&edge_infos_lock, flags);
	list_del(&einfo->list);
	spin_unlock_irqrestore(&edge_infos_lock, flags);
missing_key:
	kfree(einfo);
edge_info_alloc_fail:
	return rc;
}

static int glink_bgcom_remove(struct platform_device *pdev)
{
	struct edge_info *einfo;
	unsigned long flags;

	einfo = (struct edge_info *)dev_get_drvdata(&pdev->dev);
	bgcom_close(&einfo->bgcom_handle);
	glink_core_unregister_transport(&einfo->xprt_if);
	kthread_flush_worker(&einfo->kworker);
	kthread_stop(einfo->task);
	einfo->task = NULL;
	spin_lock_irqsave(&edge_infos_lock, flags);
	list_del(&einfo->list);
	spin_unlock_irqrestore(&edge_infos_lock, flags);
	return 0;
}

static int glink_bgcom_resume(struct platform_device *pdev)
{
	return 0;
}

static int glink_bgcom_suspend(struct platform_device *pdev,
				   pm_message_t state)
{
	unsigned long flags;
	struct edge_info *einfo;
	bool suspend;
	int rc = -EBUSY;

	einfo = (struct edge_info *)dev_get_drvdata(&pdev->dev);
	if (strcmp(einfo->xprt_cfg.edge, "bg"))
		return 0;

	spin_lock_irqsave(&einfo->activity_lock, flags);
	suspend = !(einfo->activity_flag);
	spin_unlock_irqrestore(&einfo->activity_lock, flags);
	if (suspend)
		rc = bgcom_suspend(einfo->bgcom_handle);
	if (rc < 0)
		GLINK_ERR("%s: Could not suspend activity_flag %d, rc %d\n",
			__func__, einfo->activity_flag, rc);
	return rc;
}

static const struct of_device_id bgcom_match_table[] = {
	{ .compatible = "qcom,glink-bgcom-xprt" },
	{},
};

static struct platform_driver glink_bgcom_driver = {
	.probe = glink_bgcom_probe,
	.remove = glink_bgcom_remove,
	.resume = glink_bgcom_resume,
	.suspend = glink_bgcom_suspend,
	.driver = {
		.name = "msm_glink_bgcom_xprt",
		.owner = THIS_MODULE,
		.of_match_table = bgcom_match_table,
	},
};

static int __init glink_bgcom_xprt_init(void)
{
	int rc;

	rc = platform_driver_register(&glink_bgcom_driver);
	if (rc)
		GLINK_ERR("%s: glink_bgcom register failed %d\n", __func__, rc);

	return rc;
}
module_init(glink_bgcom_xprt_init);

static void __exit glink_bgcom_xprt_exit(void)
{
	platform_driver_unregister(&glink_bgcom_driver);
}
module_exit(glink_bgcom_xprt_exit);

MODULE_DESCRIPTION("MSM G-Link bgcom Transport");
MODULE_LICENSE("GPL v2");