Linux 4.16.11

[linux/fpc-iii.git] / drivers / hsi / clients / ssi_protocol.c

/*
 * 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>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#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>

void ssi_waketest(struct hsi_client *cl, unsigned int enable);

#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, frag->page.p, frag->size, frag->page_offset);
        }
}

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;
                /* Otherwise fall through */
        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;
                        /*
                         * Fall through. 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 trigerred\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 trigerred\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);
                /* Fall through */
        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->dev = ssi->netdev;
        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);
                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 int 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 endianess...
         * Assume that modem has the same endianess 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 0;
drop2:
        hsi_free_msg(msg);
drop:
        dev_kfree_skb(skb);
inc_dropped:
        dev->stats.tx_dropped++;

        return 0;
}

/* 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)
{
        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->dev_addr[0]        = PN_MEDIA_SOS;
        dev->addr_len           = 1;
        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) {
                dev_err(dev, "No memory for ssi protocol\n");
                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");