// SPDX-License-Identifier: GPL-2.0-only
/*
 * ssi_protocol.c
 *
 * Implementation of the SSI McSAAB improved protocol.
 *
 * Copyright (C) 2010 Nokia Corporation. All rights reserved.
 * Copyright (C) 2013 Sebastian Reichel <sre@kernel.org>
 *
 * Contact: Carlos Chinea <carlos.chinea@nokia.com>
 */

#include <linux/atomic.h>
#include <linux/clk.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/if_phonet.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/notifier.h>
#include <linux/scatterlist.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <linux/hsi/hsi.h>
#include <linux/hsi/ssi_protocol.h>

#define SSIP_TXQUEUE_LEN	100
#define SSIP_MAX_MTU		65535
#define SSIP_DEFAULT_MTU	4000
#define PN_MEDIA_SOS		21
#define SSIP_MIN_PN_HDR		6	/* FIXME: Revisit */
#define SSIP_WDTOUT		2000	/* FIXME: has to be 500 msecs */
#define SSIP_KATOUT		15	/* 15 msecs */
#define SSIP_MAX_CMDS		5 /* Number of pre-allocated commands buffers */
#define SSIP_BYTES_TO_FRAMES(x) ((((x) - 1) >> 2) + 1)
#define SSIP_CMT_LOADER_SYNC	0x11223344
/*
 * SSI protocol command definitions
 */
#define SSIP_COMMAND(data)	((data) >> 28)
#define SSIP_PAYLOAD(data)	((data) & 0xfffffff)
/* Commands */
#define SSIP_SW_BREAK		0
#define SSIP_BOOTINFO_REQ	1
#define SSIP_BOOTINFO_RESP	2
#define SSIP_WAKETEST_RESULT	3
#define SSIP_START_TRANS	4
#define SSIP_READY		5
/* Payloads */
#define SSIP_DATA_VERSION(data)	((data) & 0xff)
#define SSIP_LOCAL_VERID	1
#define SSIP_WAKETEST_OK	0
#define SSIP_WAKETEST_FAILED	1
#define SSIP_PDU_LENGTH(data)	(((data) >> 8) & 0xffff)
#define SSIP_MSG_ID(data)	((data) & 0xff)
/* Generic Command */
#define SSIP_CMD(cmd, payload)	(((cmd) << 28) | ((payload) & 0xfffffff))
/* Commands for the control channel */
#define SSIP_BOOTINFO_REQ_CMD(ver) \
		SSIP_CMD(SSIP_BOOTINFO_REQ, SSIP_DATA_VERSION(ver))
#define SSIP_BOOTINFO_RESP_CMD(ver) \
		SSIP_CMD(SSIP_BOOTINFO_RESP, SSIP_DATA_VERSION(ver))
#define SSIP_START_TRANS_CMD(pdulen, id) \
		SSIP_CMD(SSIP_START_TRANS, (((pdulen) << 8) | SSIP_MSG_ID(id)))
#define SSIP_READY_CMD		SSIP_CMD(SSIP_READY, 0)
#define SSIP_SWBREAK_CMD	SSIP_CMD(SSIP_SW_BREAK, 0)

#define SSIP_WAKETEST_FLAG 0

/* Main state machine states */
enum {
	INIT,
	HANDSHAKE,
	ACTIVE,
};

/* Send state machine states */
enum {
	SEND_IDLE,
	WAIT4READY,
	SEND_READY,
	SENDING,
	SENDING_SWBREAK,
};

/* Receive state machine states */
enum {
	RECV_IDLE,
	RECV_READY,
	RECEIVING,
};

/**
 * struct ssi_protocol - SSI protocol (McSAAB) data
 * @main_state: Main state machine
 * @send_state: TX state machine
 * @recv_state: RX state machine
 * @flags: Flags, currently only used to follow wake line test
 * @rxid: RX data id
 * @txid: TX data id
 * @txqueue_len: TX queue length
 * @tx_wd: TX watchdog
 * @rx_wd: RX watchdog
 * @keep_alive: Workaround for SSI HW bug
 * @lock: To serialize access to this struct
 * @netdev: Phonet network device
 * @txqueue: TX data queue
 * @cmdqueue: Queue of free commands
 * @cl: HSI client own reference
 * @link: Link for ssip_list
 * @tx_usecount: Refcount to keep track the slaves that use the wake line
 * @channel_id_cmd: HSI channel id for command stream
 * @channel_id_data: HSI channel id for data stream
 */
struct ssi_protocol {
	unsigned int		main_state;
	unsigned int		send_state;
	unsigned int		recv_state;
	unsigned long		flags;
	u8			rxid;
	u8			txid;
	unsigned int		txqueue_len;
	struct timer_list	tx_wd;
	struct timer_list	rx_wd;
	struct timer_list	keep_alive; /* wake-up workaround */
	spinlock_t		lock;
	struct net_device	*netdev;
	struct list_head	txqueue;
	struct list_head	cmdqueue;
	struct work_struct	work;
	struct hsi_client	*cl;
	struct list_head	link;
	atomic_t		tx_usecnt;
	int			channel_id_cmd;
	int			channel_id_data;
};

/* List of ssi protocol instances */
static LIST_HEAD(ssip_list);

static void ssip_rxcmd_complete(struct hsi_msg *msg);

static inline void ssip_set_cmd(struct hsi_msg *msg, u32 cmd)
{
	u32 *data;

	data = sg_virt(msg->sgt.sgl);
	*data = cmd;
}

static inline u32 ssip_get_cmd(struct hsi_msg *msg)
{
	u32 *data;

	data = sg_virt(msg->sgt.sgl);

	return *data;
}

static void ssip_skb_to_msg(struct sk_buff *skb, struct hsi_msg *msg)
{
	skb_frag_t *frag;
	struct scatterlist *sg;
	int i;

	BUG_ON(msg->sgt.nents != (unsigned int)(skb_shinfo(skb)->nr_frags + 1));

	sg = msg->sgt.sgl;
	sg_set_buf(sg, skb->data, skb_headlen(skb));
	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		sg = sg_next(sg);
		BUG_ON(!sg);
		frag = &skb_shinfo(skb)->frags[i];
		sg_set_page(sg, skb_frag_page(frag), skb_frag_size(frag),
				skb_frag_off(frag));
	}
}

static void ssip_free_data(struct hsi_msg *msg)
{
	struct sk_buff *skb;

	skb = msg->context;
	pr_debug("free data: msg %p context %p skb %p\n", msg, msg->context,
								skb);
	msg->destructor = NULL;
	dev_kfree_skb(skb);
	hsi_free_msg(msg);
}

static struct hsi_msg *ssip_alloc_data(struct ssi_protocol *ssi,
					struct sk_buff *skb, gfp_t flags)
{
	struct hsi_msg *msg;

	msg = hsi_alloc_msg(skb_shinfo(skb)->nr_frags + 1, flags);
	if (!msg)
		return NULL;
	ssip_skb_to_msg(skb, msg);
	msg->destructor = ssip_free_data;
	msg->channel = ssi->channel_id_data;
	msg->context = skb;

	return msg;
}

static inline void ssip_release_cmd(struct hsi_msg *msg)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(msg->cl);

	dev_dbg(&msg->cl->device, "Release cmd 0x%08x\n", ssip_get_cmd(msg));
	spin_lock_bh(&ssi->lock);
	list_add_tail(&msg->link, &ssi->cmdqueue);
	spin_unlock_bh(&ssi->lock);
}

static struct hsi_msg *ssip_claim_cmd(struct ssi_protocol *ssi)
{
	struct hsi_msg *msg;

	BUG_ON(list_empty(&ssi->cmdqueue));

	spin_lock_bh(&ssi->lock);
	msg = list_first_entry(&ssi->cmdqueue, struct hsi_msg, link);
	list_del(&msg->link);
	spin_unlock_bh(&ssi->lock);
	msg->destructor = ssip_release_cmd;

	return msg;
}

static void ssip_free_cmds(struct ssi_protocol *ssi)
{
	struct hsi_msg *msg, *tmp;

	list_for_each_entry_safe(msg, tmp, &ssi->cmdqueue, link) {
		list_del(&msg->link);
		msg->destructor = NULL;
		kfree(sg_virt(msg->sgt.sgl));
		hsi_free_msg(msg);
	}
}

static int ssip_alloc_cmds(struct ssi_protocol *ssi)
{
	struct hsi_msg *msg;
	u32 *buf;
	unsigned int i;

	for (i = 0; i < SSIP_MAX_CMDS; i++) {
		msg = hsi_alloc_msg(1, GFP_KERNEL);
		if (!msg)
			goto out;
		buf = kmalloc(sizeof(*buf), GFP_KERNEL);
		if (!buf) {
			hsi_free_msg(msg);
			goto out;
		}
		sg_init_one(msg->sgt.sgl, buf, sizeof(*buf));
		msg->channel = ssi->channel_id_cmd;
		list_add_tail(&msg->link, &ssi->cmdqueue);
	}

	return 0;
out:
	ssip_free_cmds(ssi);

	return -ENOMEM;
}

static void ssip_set_rxstate(struct ssi_protocol *ssi, unsigned int state)
{
	ssi->recv_state = state;
	switch (state) {
	case RECV_IDLE:
		del_timer(&ssi->rx_wd);
		if (ssi->send_state == SEND_IDLE)
			del_timer(&ssi->keep_alive);
		break;
	case RECV_READY:
		/* CMT speech workaround */
		if (atomic_read(&ssi->tx_usecnt))
			break;
		fallthrough;
	case RECEIVING:
		mod_timer(&ssi->keep_alive, jiffies +
						msecs_to_jiffies(SSIP_KATOUT));
		mod_timer(&ssi->rx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
		break;
	default:
		break;
	}
}

static void ssip_set_txstate(struct ssi_protocol *ssi, unsigned int state)
{
	ssi->send_state = state;
	switch (state) {
	case SEND_IDLE:
	case SEND_READY:
		del_timer(&ssi->tx_wd);
		if (ssi->recv_state == RECV_IDLE)
			del_timer(&ssi->keep_alive);
		break;
	case WAIT4READY:
	case SENDING:
	case SENDING_SWBREAK:
		mod_timer(&ssi->keep_alive,
				jiffies + msecs_to_jiffies(SSIP_KATOUT));
		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
		break;
	default:
		break;
	}
}

struct hsi_client *ssip_slave_get_master(struct hsi_client *slave)
{
	struct hsi_client *master = ERR_PTR(-ENODEV);
	struct ssi_protocol *ssi;

	list_for_each_entry(ssi, &ssip_list, link)
		if (slave->device.parent == ssi->cl->device.parent) {
			master = ssi->cl;
			break;
		}

	return master;
}
EXPORT_SYMBOL_GPL(ssip_slave_get_master);

int ssip_slave_start_tx(struct hsi_client *master)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(master);

	dev_dbg(&master->device, "start TX %d\n", atomic_read(&ssi->tx_usecnt));
	spin_lock_bh(&ssi->lock);
	if (ssi->send_state == SEND_IDLE) {
		ssip_set_txstate(ssi, WAIT4READY);
		hsi_start_tx(master);
	}
	spin_unlock_bh(&ssi->lock);
	atomic_inc(&ssi->tx_usecnt);

	return 0;
}
EXPORT_SYMBOL_GPL(ssip_slave_start_tx);

int ssip_slave_stop_tx(struct hsi_client *master)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(master);

	WARN_ON_ONCE(atomic_read(&ssi->tx_usecnt) == 0);

	if (atomic_dec_and_test(&ssi->tx_usecnt)) {
		spin_lock_bh(&ssi->lock);
		if ((ssi->send_state == SEND_READY) ||
			(ssi->send_state == WAIT4READY)) {
			ssip_set_txstate(ssi, SEND_IDLE);
			hsi_stop_tx(master);
		}
		spin_unlock_bh(&ssi->lock);
	}
	dev_dbg(&master->device, "stop TX %d\n", atomic_read(&ssi->tx_usecnt));

	return 0;
}
EXPORT_SYMBOL_GPL(ssip_slave_stop_tx);

int ssip_slave_running(struct hsi_client *master)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(master);
	return netif_running(ssi->netdev);
}
EXPORT_SYMBOL_GPL(ssip_slave_running);

static void ssip_reset(struct hsi_client *cl)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct list_head *head, *tmp;
	struct hsi_msg *msg;

	if (netif_running(ssi->netdev))
		netif_carrier_off(ssi->netdev);
	hsi_flush(cl);
	spin_lock_bh(&ssi->lock);
	if (ssi->send_state != SEND_IDLE)
		hsi_stop_tx(cl);
	spin_unlock_bh(&ssi->lock);
	if (test_and_clear_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
		ssi_waketest(cl, 0); /* FIXME: To be removed */
	spin_lock_bh(&ssi->lock);
	del_timer(&ssi->rx_wd);
	del_timer(&ssi->tx_wd);
	del_timer(&ssi->keep_alive);
	ssi->main_state = 0;
	ssi->send_state = 0;
	ssi->recv_state = 0;
	ssi->flags = 0;
	ssi->rxid = 0;
	ssi->txid = 0;
	list_for_each_safe(head, tmp, &ssi->txqueue) {
		msg = list_entry(head, struct hsi_msg, link);
		dev_dbg(&cl->device, "Pending TX data\n");
		list_del(head);
		ssip_free_data(msg);
	}
	ssi->txqueue_len = 0;
	spin_unlock_bh(&ssi->lock);
}

static void ssip_dump_state(struct hsi_client *cl)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct hsi_msg *msg;

	spin_lock_bh(&ssi->lock);
	dev_err(&cl->device, "Main state: %d\n", ssi->main_state);
	dev_err(&cl->device, "Recv state: %d\n", ssi->recv_state);
	dev_err(&cl->device, "Send state: %d\n", ssi->send_state);
	dev_err(&cl->device, "CMT %s\n", (ssi->main_state == ACTIVE) ?
							"Online" : "Offline");
	dev_err(&cl->device, "Wake test %d\n",
				test_bit(SSIP_WAKETEST_FLAG, &ssi->flags));
	dev_err(&cl->device, "Data RX id: %d\n", ssi->rxid);
	dev_err(&cl->device, "Data TX id: %d\n", ssi->txid);

	list_for_each_entry(msg, &ssi->txqueue, link)
		dev_err(&cl->device, "pending TX data (%p)\n", msg);
	spin_unlock_bh(&ssi->lock);
}

static void ssip_error(struct hsi_client *cl)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct hsi_msg *msg;

	ssip_dump_state(cl);
	ssip_reset(cl);
	msg = ssip_claim_cmd(ssi);
	msg->complete = ssip_rxcmd_complete;
	hsi_async_read(cl, msg);
}

static void ssip_keep_alive(struct timer_list *t)
{
	struct ssi_protocol *ssi = from_timer(ssi, t, keep_alive);
	struct hsi_client *cl = ssi->cl;

	dev_dbg(&cl->device, "Keep alive kick in: m(%d) r(%d) s(%d)\n",
		ssi->main_state, ssi->recv_state, ssi->send_state);

	spin_lock(&ssi->lock);
	if (ssi->recv_state == RECV_IDLE)
		switch (ssi->send_state) {
		case SEND_READY:
			if (atomic_read(&ssi->tx_usecnt) == 0)
				break;
			fallthrough;
			/*
			 * Workaround for cmt-speech in that case
			 * we relay on audio timers.
			 */
		case SEND_IDLE:
			spin_unlock(&ssi->lock);
			return;
		}
	mod_timer(&ssi->keep_alive, jiffies + msecs_to_jiffies(SSIP_KATOUT));
	spin_unlock(&ssi->lock);
}

static void ssip_rx_wd(struct timer_list *t)
{
	struct ssi_protocol *ssi = from_timer(ssi, t, rx_wd);
	struct hsi_client *cl = ssi->cl;

	dev_err(&cl->device, "Watchdog triggered\n");
	ssip_error(cl);
}

static void ssip_tx_wd(struct timer_list *t)
{
	struct ssi_protocol *ssi = from_timer(ssi, t, tx_wd);
	struct hsi_client *cl = ssi->cl;

	dev_err(&cl->device, "Watchdog triggered\n");
	ssip_error(cl);
}

static void ssip_send_bootinfo_req_cmd(struct hsi_client *cl)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct hsi_msg *msg;

	dev_dbg(&cl->device, "Issuing BOOT INFO REQ command\n");
	msg = ssip_claim_cmd(ssi);
	ssip_set_cmd(msg, SSIP_BOOTINFO_REQ_CMD(SSIP_LOCAL_VERID));
	msg->complete = ssip_release_cmd;
	hsi_async_write(cl, msg);
	dev_dbg(&cl->device, "Issuing RX command\n");
	msg = ssip_claim_cmd(ssi);
	msg->complete = ssip_rxcmd_complete;
	hsi_async_read(cl, msg);
}

static void ssip_start_rx(struct hsi_client *cl)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct hsi_msg *msg;

	dev_dbg(&cl->device, "RX start M(%d) R(%d)\n", ssi->main_state,
						ssi->recv_state);
	spin_lock_bh(&ssi->lock);
	/*
	 * We can have two UP events in a row due to a short low
	 * high transition. Therefore we need to ignore the sencond UP event.
	 */
	if ((ssi->main_state != ACTIVE) || (ssi->recv_state == RECV_READY)) {
		spin_unlock_bh(&ssi->lock);
		return;
	}
	ssip_set_rxstate(ssi, RECV_READY);
	spin_unlock_bh(&ssi->lock);

	msg = ssip_claim_cmd(ssi);
	ssip_set_cmd(msg, SSIP_READY_CMD);
	msg->complete = ssip_release_cmd;
	dev_dbg(&cl->device, "Send READY\n");
	hsi_async_write(cl, msg);
}

static void ssip_stop_rx(struct hsi_client *cl)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);

	dev_dbg(&cl->device, "RX stop M(%d)\n", ssi->main_state);
	spin_lock_bh(&ssi->lock);
	if (likely(ssi->main_state == ACTIVE))
		ssip_set_rxstate(ssi, RECV_IDLE);
	spin_unlock_bh(&ssi->lock);
}

static void ssip_free_strans(struct hsi_msg *msg)
{
	ssip_free_data(msg->context);
	ssip_release_cmd(msg);
}

static void ssip_strans_complete(struct hsi_msg *msg)
{
	struct hsi_client *cl = msg->cl;
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct hsi_msg *data;

	data = msg->context;
	ssip_release_cmd(msg);
	spin_lock_bh(&ssi->lock);
	ssip_set_txstate(ssi, SENDING);
	spin_unlock_bh(&ssi->lock);
	hsi_async_write(cl, data);
}

static int ssip_xmit(struct hsi_client *cl)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct hsi_msg *msg, *dmsg;
	struct sk_buff *skb;

	spin_lock_bh(&ssi->lock);
	if (list_empty(&ssi->txqueue)) {
		spin_unlock_bh(&ssi->lock);
		return 0;
	}
	dmsg = list_first_entry(&ssi->txqueue, struct hsi_msg, link);
	list_del(&dmsg->link);
	ssi->txqueue_len--;
	spin_unlock_bh(&ssi->lock);

	msg = ssip_claim_cmd(ssi);
	skb = dmsg->context;
	msg->context = dmsg;
	msg->complete = ssip_strans_complete;
	msg->destructor = ssip_free_strans;

	spin_lock_bh(&ssi->lock);
	ssip_set_cmd(msg, SSIP_START_TRANS_CMD(SSIP_BYTES_TO_FRAMES(skb->len),
								ssi->txid));
	ssi->txid++;
	ssip_set_txstate(ssi, SENDING);
	spin_unlock_bh(&ssi->lock);

	dev_dbg(&cl->device, "Send STRANS (%d frames)\n",
						SSIP_BYTES_TO_FRAMES(skb->len));

	return hsi_async_write(cl, msg);
}

/* In soft IRQ context */
static void ssip_pn_rx(struct sk_buff *skb)
{
	struct net_device *dev = skb->dev;

	if (unlikely(!netif_running(dev))) {
		dev_dbg(&dev->dev, "Drop RX packet\n");
		dev->stats.rx_dropped++;
		dev_kfree_skb(skb);
		return;
	}
	if (unlikely(!pskb_may_pull(skb, SSIP_MIN_PN_HDR))) {
		dev_dbg(&dev->dev, "Error drop RX packet\n");
		dev->stats.rx_errors++;
		dev->stats.rx_length_errors++;
		dev_kfree_skb(skb);
		return;
	}
	dev->stats.rx_packets++;
	dev->stats.rx_bytes += skb->len;

	/* length field is exchanged in network byte order */
	((u16 *)skb->data)[2] = ntohs(((u16 *)skb->data)[2]);
	dev_dbg(&dev->dev, "RX length fixed (%04x -> %u)\n",
			((u16 *)skb->data)[2], ntohs(((u16 *)skb->data)[2]));

	skb->protocol = htons(ETH_P_PHONET);
	skb_reset_mac_header(skb);
	__skb_pull(skb, 1);
	netif_rx(skb);
}

static void ssip_rx_data_complete(struct hsi_msg *msg)
{
	struct hsi_client *cl = msg->cl;
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct sk_buff *skb;

	if (msg->status == HSI_STATUS_ERROR) {
		dev_err(&cl->device, "RX data error\n");
		ssip_free_data(msg);
		ssip_error(cl);
		return;
	}
	del_timer(&ssi->rx_wd); /* FIXME: Revisit */
	skb = msg->context;
	ssip_pn_rx(skb);
	hsi_free_msg(msg);
}

static void ssip_rx_bootinforeq(struct hsi_client *cl, u32 cmd)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct hsi_msg *msg;

	/* Workaroud: Ignore CMT Loader message leftover */
	if (cmd == SSIP_CMT_LOADER_SYNC)
		return;

	switch (ssi->main_state) {
	case ACTIVE:
		dev_err(&cl->device, "Boot info req on active state\n");
		ssip_error(cl);
		fallthrough;
	case INIT:
	case HANDSHAKE:
		spin_lock_bh(&ssi->lock);
		ssi->main_state = HANDSHAKE;
		spin_unlock_bh(&ssi->lock);

		if (!test_and_set_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
			ssi_waketest(cl, 1); /* FIXME: To be removed */

		spin_lock_bh(&ssi->lock);
		/* Start boot handshake watchdog */
		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
		spin_unlock_bh(&ssi->lock);
		dev_dbg(&cl->device, "Send BOOTINFO_RESP\n");
		if (SSIP_DATA_VERSION(cmd) != SSIP_LOCAL_VERID)
			dev_warn(&cl->device, "boot info req verid mismatch\n");
		msg = ssip_claim_cmd(ssi);
		ssip_set_cmd(msg, SSIP_BOOTINFO_RESP_CMD(SSIP_LOCAL_VERID));
		msg->complete = ssip_release_cmd;
		hsi_async_write(cl, msg);
		break;
	default:
		dev_dbg(&cl->device, "Wrong state M(%d)\n", ssi->main_state);
		break;
	}
}

static void ssip_rx_bootinforesp(struct hsi_client *cl, u32 cmd)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);

	if (SSIP_DATA_VERSION(cmd) != SSIP_LOCAL_VERID)
		dev_warn(&cl->device, "boot info resp verid mismatch\n");

	spin_lock_bh(&ssi->lock);
	if (ssi->main_state != ACTIVE)
		/* Use tx_wd as a boot watchdog in non ACTIVE state */
		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
	else
		dev_dbg(&cl->device, "boot info resp ignored M(%d)\n",
							ssi->main_state);
	spin_unlock_bh(&ssi->lock);
}

static void ssip_rx_waketest(struct hsi_client *cl, u32 cmd)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	unsigned int wkres = SSIP_PAYLOAD(cmd);

	spin_lock_bh(&ssi->lock);
	if (ssi->main_state != HANDSHAKE) {
		dev_dbg(&cl->device, "wake lines test ignored M(%d)\n",
							ssi->main_state);
		spin_unlock_bh(&ssi->lock);
		return;
	}
	spin_unlock_bh(&ssi->lock);

	if (test_and_clear_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
		ssi_waketest(cl, 0); /* FIXME: To be removed */

	spin_lock_bh(&ssi->lock);
	ssi->main_state = ACTIVE;
	del_timer(&ssi->tx_wd); /* Stop boot handshake timer */
	spin_unlock_bh(&ssi->lock);

	dev_notice(&cl->device, "WAKELINES TEST %s\n",
				wkres & SSIP_WAKETEST_FAILED ? "FAILED" : "OK");
	if (wkres & SSIP_WAKETEST_FAILED) {
		ssip_error(cl);
		return;
	}
	dev_dbg(&cl->device, "CMT is ONLINE\n");
	netif_wake_queue(ssi->netdev);
	netif_carrier_on(ssi->netdev);
}

static void ssip_rx_ready(struct hsi_client *cl)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);

	spin_lock_bh(&ssi->lock);
	if (unlikely(ssi->main_state != ACTIVE)) {
		dev_dbg(&cl->device, "READY on wrong state: S(%d) M(%d)\n",
					ssi->send_state, ssi->main_state);
		spin_unlock_bh(&ssi->lock);
		return;
	}
	if (ssi->send_state != WAIT4READY) {
		dev_dbg(&cl->device, "Ignore spurious READY command\n");
		spin_unlock_bh(&ssi->lock);
		return;
	}
	ssip_set_txstate(ssi, SEND_READY);
	spin_unlock_bh(&ssi->lock);
	ssip_xmit(cl);
}

static void ssip_rx_strans(struct hsi_client *cl, u32 cmd)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct sk_buff *skb;
	struct hsi_msg *msg;
	int len = SSIP_PDU_LENGTH(cmd);

	dev_dbg(&cl->device, "RX strans: %d frames\n", len);
	spin_lock_bh(&ssi->lock);
	if (unlikely(ssi->main_state != ACTIVE)) {
		dev_err(&cl->device, "START TRANS wrong state: S(%d) M(%d)\n",
					ssi->send_state, ssi->main_state);
		spin_unlock_bh(&ssi->lock);
		return;
	}
	ssip_set_rxstate(ssi, RECEIVING);
	if (unlikely(SSIP_MSG_ID(cmd) != ssi->rxid)) {
		dev_err(&cl->device, "START TRANS id %d expected %d\n",
					SSIP_MSG_ID(cmd), ssi->rxid);
		spin_unlock_bh(&ssi->lock);
		goto out1;
	}
	ssi->rxid++;
	spin_unlock_bh(&ssi->lock);
	skb = netdev_alloc_skb(ssi->netdev, len * 4);
	if (unlikely(!skb)) {
		dev_err(&cl->device, "No memory for rx skb\n");
		goto out1;
	}
	skb_put(skb, len * 4);
	msg = ssip_alloc_data(ssi, skb, GFP_ATOMIC);
	if (unlikely(!msg)) {
		dev_err(&cl->device, "No memory for RX data msg\n");
		goto out2;
	}
	msg->complete = ssip_rx_data_complete;
	hsi_async_read(cl, msg);

	return;
out2:
	dev_kfree_skb(skb);
out1:
	ssip_error(cl);
}

static void ssip_rxcmd_complete(struct hsi_msg *msg)
{
	struct hsi_client *cl = msg->cl;
	u32 cmd = ssip_get_cmd(msg);
	unsigned int cmdid = SSIP_COMMAND(cmd);

	if (msg->status == HSI_STATUS_ERROR) {
		dev_err(&cl->device, "RX error detected\n");
		ssip_release_cmd(msg);
		ssip_error(cl);
		return;
	}
	hsi_async_read(cl, msg);
	dev_dbg(&cl->device, "RX cmd: 0x%08x\n", cmd);
	switch (cmdid) {
	case SSIP_SW_BREAK:
		/* Ignored */
		break;
	case SSIP_BOOTINFO_REQ:
		ssip_rx_bootinforeq(cl, cmd);
		break;
	case SSIP_BOOTINFO_RESP:
		ssip_rx_bootinforesp(cl, cmd);
		break;
	case SSIP_WAKETEST_RESULT:
		ssip_rx_waketest(cl, cmd);
		break;
	case SSIP_START_TRANS:
		ssip_rx_strans(cl, cmd);
		break;
	case SSIP_READY:
		ssip_rx_ready(cl);
		break;
	default:
		dev_warn(&cl->device, "command 0x%08x not supported\n", cmd);
		break;
	}
}

static void ssip_swbreak_complete(struct hsi_msg *msg)
{
	struct hsi_client *cl = msg->cl;
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);

	ssip_release_cmd(msg);
	spin_lock_bh(&ssi->lock);
	if (list_empty(&ssi->txqueue)) {
		if (atomic_read(&ssi->tx_usecnt)) {
			ssip_set_txstate(ssi, SEND_READY);
		} else {
			ssip_set_txstate(ssi, SEND_IDLE);
			hsi_stop_tx(cl);
		}
		spin_unlock_bh(&ssi->lock);
	} else {
		spin_unlock_bh(&ssi->lock);
		ssip_xmit(cl);
	}
	netif_wake_queue(ssi->netdev);
}

static void ssip_tx_data_complete(struct hsi_msg *msg)
{
	struct hsi_client *cl = msg->cl;
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct hsi_msg *cmsg;

	if (msg->status == HSI_STATUS_ERROR) {
		dev_err(&cl->device, "TX data error\n");
		ssip_error(cl);
		goto out;
	}
	spin_lock_bh(&ssi->lock);
	if (list_empty(&ssi->txqueue)) {
		ssip_set_txstate(ssi, SENDING_SWBREAK);
		spin_unlock_bh(&ssi->lock);
		cmsg = ssip_claim_cmd(ssi);
		ssip_set_cmd(cmsg, SSIP_SWBREAK_CMD);
		cmsg->complete = ssip_swbreak_complete;
		dev_dbg(&cl->device, "Send SWBREAK\n");
		hsi_async_write(cl, cmsg);
	} else {
		spin_unlock_bh(&ssi->lock);
		ssip_xmit(cl);
	}
out:
	ssip_free_data(msg);
}

static void ssip_port_event(struct hsi_client *cl, unsigned long event)
{
	switch (event) {
	case HSI_EVENT_START_RX:
		ssip_start_rx(cl);
		break;
	case HSI_EVENT_STOP_RX:
		ssip_stop_rx(cl);
		break;
	default:
		return;
	}
}

static int ssip_pn_open(struct net_device *dev)
{
	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	int err;

	err = hsi_claim_port(cl, 1);
	if (err < 0) {
		dev_err(&cl->device, "SSI port already claimed\n");
		return err;
	}
	err = hsi_register_port_event(cl, ssip_port_event);
	if (err < 0) {
		dev_err(&cl->device, "Register HSI port event failed (%d)\n",
			err);
		hsi_release_port(cl);
		return err;
	}
	dev_dbg(&cl->device, "Configuring SSI port\n");
	hsi_setup(cl);

	if (!test_and_set_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
		ssi_waketest(cl, 1); /* FIXME: To be removed */

	spin_lock_bh(&ssi->lock);
	ssi->main_state = HANDSHAKE;
	spin_unlock_bh(&ssi->lock);

	ssip_send_bootinfo_req_cmd(cl);

	return 0;
}

static int ssip_pn_stop(struct net_device *dev)
{
	struct hsi_client *cl = to_hsi_client(dev->dev.parent);

	ssip_reset(cl);
	hsi_unregister_port_event(cl);
	hsi_release_port(cl);

	return 0;
}

static void ssip_xmit_work(struct work_struct *work)
{
	struct ssi_protocol *ssi =
				container_of(work, struct ssi_protocol, work);
	struct hsi_client *cl = ssi->cl;

	ssip_xmit(cl);
}

static netdev_tx_t ssip_pn_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
	struct hsi_msg *msg;

	if ((skb->protocol != htons(ETH_P_PHONET)) ||
					(skb->len < SSIP_MIN_PN_HDR))
		goto drop;
	/* Pad to 32-bits - FIXME: Revisit*/
	if ((skb->len & 3) && skb_pad(skb, 4 - (skb->len & 3)))
		goto inc_dropped;

	/*
	 * Modem sends Phonet messages over SSI with its own endianness.
	 * Assume that modem has the same endianness as we do.
	 */
	if (skb_cow_head(skb, 0))
		goto drop;

	/* length field is exchanged in network byte order */
	((u16 *)skb->data)[2] = htons(((u16 *)skb->data)[2]);

	msg = ssip_alloc_data(ssi, skb, GFP_ATOMIC);
	if (!msg) {
		dev_dbg(&cl->device, "Dropping tx data: No memory\n");
		goto drop;
	}
	msg->complete = ssip_tx_data_complete;

	spin_lock_bh(&ssi->lock);
	if (unlikely(ssi->main_state != ACTIVE)) {
		spin_unlock_bh(&ssi->lock);
		dev_dbg(&cl->device, "Dropping tx data: CMT is OFFLINE\n");
		goto drop2;
	}
	list_add_tail(&msg->link, &ssi->txqueue);
	ssi->txqueue_len++;
	if (dev->tx_queue_len < ssi->txqueue_len) {
		dev_info(&cl->device, "TX queue full %d\n", ssi->txqueue_len);
		netif_stop_queue(dev);
	}
	if (ssi->send_state == SEND_IDLE) {
		ssip_set_txstate(ssi, WAIT4READY);
		spin_unlock_bh(&ssi->lock);
		dev_dbg(&cl->device, "Start TX qlen %d\n", ssi->txqueue_len);
		hsi_start_tx(cl);
	} else if (ssi->send_state == SEND_READY) {
		/* Needed for cmt-speech workaround */
		dev_dbg(&cl->device, "Start TX on SEND READY qlen %d\n",
							ssi->txqueue_len);
		spin_unlock_bh(&ssi->lock);
		schedule_work(&ssi->work);
	} else {
		spin_unlock_bh(&ssi->lock);
	}
	dev->stats.tx_packets++;
	dev->stats.tx_bytes += skb->len;

	return NETDEV_TX_OK;
drop2:
	hsi_free_msg(msg);
drop:
	dev_kfree_skb(skb);
inc_dropped:
	dev->stats.tx_dropped++;

	return NETDEV_TX_OK;
}

/* CMT reset event handler */
void ssip_reset_event(struct hsi_client *master)
{
	struct ssi_protocol *ssi = hsi_client_drvdata(master);
	dev_err(&ssi->cl->device, "CMT reset detected!\n");
	ssip_error(ssi->cl);
}
EXPORT_SYMBOL_GPL(ssip_reset_event);

static const struct net_device_ops ssip_pn_ops = {
	.ndo_open	= ssip_pn_open,
	.ndo_stop	= ssip_pn_stop,
	.ndo_start_xmit	= ssip_pn_xmit,
};

static void ssip_pn_setup(struct net_device *dev)
{
	static const u8 addr = PN_MEDIA_SOS;

	dev->features		= 0;
	dev->netdev_ops		= &ssip_pn_ops;
	dev->type		= ARPHRD_PHONET;
	dev->flags		= IFF_POINTOPOINT | IFF_NOARP;
	dev->mtu		= SSIP_DEFAULT_MTU;
	dev->hard_header_len	= 1;
	dev->addr_len		= 1;
	dev_addr_set(dev, &addr);
	dev->tx_queue_len	= SSIP_TXQUEUE_LEN;

	dev->needs_free_netdev	= true;
	dev->header_ops		= &phonet_header_ops;
}

static int ssi_protocol_probe(struct device *dev)
{
	static const char ifname[] = "phonet%d";
	struct hsi_client *cl = to_hsi_client(dev);
	struct ssi_protocol *ssi;
	int err;

	ssi = kzalloc(sizeof(*ssi), GFP_KERNEL);
	if (!ssi)
		return -ENOMEM;

	spin_lock_init(&ssi->lock);
	timer_setup(&ssi->rx_wd, ssip_rx_wd, TIMER_DEFERRABLE);
	timer_setup(&ssi->tx_wd, ssip_tx_wd, TIMER_DEFERRABLE);
	timer_setup(&ssi->keep_alive, ssip_keep_alive, 0);
	INIT_LIST_HEAD(&ssi->txqueue);
	INIT_LIST_HEAD(&ssi->cmdqueue);
	atomic_set(&ssi->tx_usecnt, 0);
	hsi_client_set_drvdata(cl, ssi);
	ssi->cl = cl;
	INIT_WORK(&ssi->work, ssip_xmit_work);

	ssi->channel_id_cmd = hsi_get_channel_id_by_name(cl, "mcsaab-control");
	if (ssi->channel_id_cmd < 0) {
		err = ssi->channel_id_cmd;
		dev_err(dev, "Could not get cmd channel (%d)\n", err);
		goto out;
	}

	ssi->channel_id_data = hsi_get_channel_id_by_name(cl, "mcsaab-data");
	if (ssi->channel_id_data < 0) {
		err = ssi->channel_id_data;
		dev_err(dev, "Could not get data channel (%d)\n", err);
		goto out;
	}

	err = ssip_alloc_cmds(ssi);
	if (err < 0) {
		dev_err(dev, "No memory for commands\n");
		goto out;
	}

	ssi->netdev = alloc_netdev(0, ifname, NET_NAME_UNKNOWN, ssip_pn_setup);
	if (!ssi->netdev) {
		dev_err(dev, "No memory for netdev\n");
		err = -ENOMEM;
		goto out1;
	}

	/* MTU range: 6 - 65535 */
	ssi->netdev->min_mtu = PHONET_MIN_MTU;
	ssi->netdev->max_mtu = SSIP_MAX_MTU;

	SET_NETDEV_DEV(ssi->netdev, dev);
	netif_carrier_off(ssi->netdev);
	err = register_netdev(ssi->netdev);
	if (err < 0) {
		dev_err(dev, "Register netdev failed (%d)\n", err);
		goto out2;
	}

	list_add(&ssi->link, &ssip_list);

	dev_dbg(dev, "channel configuration: cmd=%d, data=%d\n",
		ssi->channel_id_cmd, ssi->channel_id_data);

	return 0;
out2:
	free_netdev(ssi->netdev);
out1:
	ssip_free_cmds(ssi);
out:
	kfree(ssi);

	return err;
}

static int ssi_protocol_remove(struct device *dev)
{
	struct hsi_client *cl = to_hsi_client(dev);
	struct ssi_protocol *ssi = hsi_client_drvdata(cl);

	list_del(&ssi->link);
	unregister_netdev(ssi->netdev);
	ssip_free_cmds(ssi);
	hsi_client_set_drvdata(cl, NULL);
	kfree(ssi);

	return 0;
}

static struct hsi_client_driver ssip_driver = {
	.driver = {
		.name	= "ssi-protocol",
		.owner	= THIS_MODULE,
		.probe	= ssi_protocol_probe,
		.remove	= ssi_protocol_remove,
	},
};

static int __init ssip_init(void)
{
	pr_info("SSI protocol aka McSAAB added\n");

	return hsi_register_client_driver(&ssip_driver);
}
module_init(ssip_init);

static void __exit ssip_exit(void)
{
	hsi_unregister_client_driver(&ssip_driver);
	pr_info("SSI protocol driver removed\n");
}
module_exit(ssip_exit);

MODULE_ALIAS("hsi:ssi-protocol");
MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
MODULE_AUTHOR("Remi Denis-Courmont <remi.denis-courmont@nokia.com>");
MODULE_DESCRIPTION("SSI protocol improved aka McSAAB");
MODULE_LICENSE("GPL");