// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
/*
 * nozomi.c  -- HSDPA driver Broadband Wireless Data Card - Globe Trotter
 *
 * Written by: Ulf Jakobsson,
 *             Jan Åkerfeldt,
 *             Stefan Thomasson,
 *
 * Maintained by: Paul Hardwick (p.hardwick@option.com)
 *
 * Patches:
 *          Locking code changes for Vodafone by Sphere Systems Ltd,
 *                              Andrew Bird (ajb@spheresystems.co.uk )
 *                              & Phil Sanderson
 *
 * Source has been ported from an implementation made by Filip Aben @ Option
 *
 * --------------------------------------------------------------------------
 *
 * Copyright (c) 2005,2006 Option Wireless Sweden AB
 * Copyright (c) 2006 Sphere Systems Ltd
 * Copyright (c) 2006 Option Wireless n/v
 * All rights Reserved.
 *
 * --------------------------------------------------------------------------
 */

/* Enable this to have a lot of debug printouts */
#define DEBUG

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/ioport.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/sched.h>
#include <linux/serial.h>
#include <linux/interrupt.h>
#include <linux/kmod.h>
#include <linux/init.h>
#include <linux/kfifo.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <asm/byteorder.h>

#include <linux/delay.h>


#define VERSION_STRING DRIVER_DESC " 2.1d"

/* Default debug printout level */
#define NOZOMI_DEBUG_LEVEL 0x00
static int debug = NOZOMI_DEBUG_LEVEL;
module_param(debug, int, S_IRUGO | S_IWUSR);

/*    Macros definitions */
#define DBG_(lvl, fmt, args...)                         \
do {                                                    \
        if (lvl & debug)                                \
                pr_debug("[%d] %s(): " fmt "\n",        \
                         __LINE__, __func__,  ##args);  \
} while (0)

#define DBG1(args...) DBG_(0x01, ##args)
#define DBG2(args...) DBG_(0x02, ##args)
#define DBG3(args...) DBG_(0x04, ##args)
#define DBG4(args...) DBG_(0x08, ##args)

/* TODO: rewrite to optimize macros... */

#define TMP_BUF_MAX 256

#define DUMP(buf__, len__)                                              \
        do {                                                            \
                char tbuf[TMP_BUF_MAX] = {0};                           \
                if (len__ > 1) {                                        \
                        u32 data_len = min_t(u32, len__, TMP_BUF_MAX);  \
                        strscpy(tbuf, buf__, data_len);                 \
                        if (tbuf[data_len - 2] == '\r')                 \
                                tbuf[data_len - 2] = 'r';               \
                        DBG1("SENDING: '%s' (%d+n)", tbuf, len__);      \
                } else {                                                \
                        DBG1("SENDING: '%s' (%d)", tbuf, len__);        \
                }                                                       \
        } while (0)

/*    Defines */
#define NOZOMI_NAME             "nozomi"
#define NOZOMI_NAME_TTY         "nozomi_tty"
#define DRIVER_DESC             "Nozomi driver"

#define NTTY_TTY_MAXMINORS      256
#define NTTY_FIFO_BUFFER_SIZE   8192

/* Must be power of 2 */
#define FIFO_BUFFER_SIZE_UL     8192

/* Size of tmp send buffer to card */
#define SEND_BUF_MAX            1024
#define RECEIVE_BUF_MAX         4


#define R_IIR                   0x0000  /* Interrupt Identity Register */
#define R_FCR                   0x0000  /* Flow Control Register */
#define R_IER                   0x0004  /* Interrupt Enable Register */

#define NOZOMI_CONFIG_MAGIC     0xEFEFFEFE
#define TOGGLE_VALID            0x0000

/* Definition of interrupt tokens */
#define MDM_DL1                 0x0001
#define MDM_UL1                 0x0002
#define MDM_DL2                 0x0004
#define MDM_UL2                 0x0008
#define DIAG_DL1                0x0010
#define DIAG_DL2                0x0020
#define DIAG_UL                 0x0040
#define APP1_DL                 0x0080
#define APP1_UL                 0x0100
#define APP2_DL                 0x0200
#define APP2_UL                 0x0400
#define CTRL_DL                 0x0800
#define CTRL_UL                 0x1000
#define RESET                   0x8000

#define MDM_DL                  (MDM_DL1  | MDM_DL2)
#define MDM_UL                  (MDM_UL1  | MDM_UL2)
#define DIAG_DL                 (DIAG_DL1 | DIAG_DL2)

/* modem signal definition */
#define CTRL_DSR                0x0001
#define CTRL_DCD                0x0002
#define CTRL_RI                 0x0004
#define CTRL_CTS                0x0008

#define CTRL_DTR                0x0001
#define CTRL_RTS                0x0002

#define MAX_PORT                4
#define NOZOMI_MAX_PORTS        5
#define NOZOMI_MAX_CARDS        (NTTY_TTY_MAXMINORS / MAX_PORT)

/*    Type definitions */

/*
 * There are two types of nozomi cards,
 * one with 2048 memory and with 8192 memory
 */
enum card_type {
        F32_2 = 2048,   /* 512 bytes downlink + uplink * 2 -> 2048 */
        F32_8 = 8192,   /* 3072 bytes downl. + 1024 bytes uplink * 2 -> 8192 */
};

/* Initialization states a card can be in */
enum card_state {
        NOZOMI_STATE_UNKNOWN    = 0,
        NOZOMI_STATE_ENABLED    = 1,    /* pci device enabled */
        NOZOMI_STATE_ALLOCATED  = 2,    /* config setup done */
        NOZOMI_STATE_READY      = 3,    /* flowcontrols received */
};

/* Two different toggle channels exist */
enum channel_type {
        CH_A = 0,
        CH_B = 1,
};

/* Port definition for the card regarding flow control */
enum ctrl_port_type {
        CTRL_CMD        = 0,
        CTRL_MDM        = 1,
        CTRL_DIAG       = 2,
        CTRL_APP1       = 3,
        CTRL_APP2       = 4,
        CTRL_ERROR      = -1,
};

/* Ports that the nozomi has */
enum port_type {
        PORT_MDM        = 0,
        PORT_DIAG       = 1,
        PORT_APP1       = 2,
        PORT_APP2       = 3,
        PORT_CTRL       = 4,
        PORT_ERROR      = -1,
};

#ifdef __BIG_ENDIAN
/* Big endian */

struct toggles {
        unsigned int enabled:5; /*
                                 * Toggle fields are valid if enabled is 0,
                                 * else A-channels must always be used.
                                 */
        unsigned int diag_dl:1;
        unsigned int mdm_dl:1;
        unsigned int mdm_ul:1;
} __attribute__ ((packed));

/* Configuration table to read at startup of card */
/* Is for now only needed during initialization phase */
struct config_table {
        u32 signature;
        u16 product_information;
        u16 version;
        u8 pad3[3];
        struct toggles toggle;
        u8 pad1[4];
        u16 dl_mdm_len1;        /*
                                 * If this is 64, it can hold
                                 * 60 bytes + 4 that is length field
                                 */
        u16 dl_start;

        u16 dl_diag_len1;
        u16 dl_mdm_len2;        /*
                                 * If this is 64, it can hold
                                 * 60 bytes + 4 that is length field
                                 */
        u16 dl_app1_len;

        u16 dl_diag_len2;
        u16 dl_ctrl_len;
        u16 dl_app2_len;
        u8 pad2[16];
        u16 ul_mdm_len1;
        u16 ul_start;
        u16 ul_diag_len;
        u16 ul_mdm_len2;
        u16 ul_app1_len;
        u16 ul_app2_len;
        u16 ul_ctrl_len;
} __attribute__ ((packed));

/* This stores all control downlink flags */
struct ctrl_dl {
        u8 port;
        unsigned int reserved:4;
        unsigned int CTS:1;
        unsigned int RI:1;
        unsigned int DCD:1;
        unsigned int DSR:1;
} __attribute__ ((packed));

/* This stores all control uplink flags */
struct ctrl_ul {
        u8 port;
        unsigned int reserved:6;
        unsigned int RTS:1;
        unsigned int DTR:1;
} __attribute__ ((packed));

#else
/* Little endian */

/* This represents the toggle information */
struct toggles {
        unsigned int mdm_ul:1;
        unsigned int mdm_dl:1;
        unsigned int diag_dl:1;
        unsigned int enabled:5; /*
                                 * Toggle fields are valid if enabled is 0,
                                 * else A-channels must always be used.
                                 */
} __attribute__ ((packed));

/* Configuration table to read at startup of card */
struct config_table {
        u32 signature;
        u16 version;
        u16 product_information;
        struct toggles toggle;
        u8 pad1[7];
        u16 dl_start;
        u16 dl_mdm_len1;        /*
                                 * If this is 64, it can hold
                                 * 60 bytes + 4 that is length field
                                 */
        u16 dl_mdm_len2;
        u16 dl_diag_len1;
        u16 dl_diag_len2;
        u16 dl_app1_len;
        u16 dl_app2_len;
        u16 dl_ctrl_len;
        u8 pad2[16];
        u16 ul_start;
        u16 ul_mdm_len2;
        u16 ul_mdm_len1;
        u16 ul_diag_len;
        u16 ul_app1_len;
        u16 ul_app2_len;
        u16 ul_ctrl_len;
} __attribute__ ((packed));

/* This stores all control downlink flags */
struct ctrl_dl {
        unsigned int DSR:1;
        unsigned int DCD:1;
        unsigned int RI:1;
        unsigned int CTS:1;
        unsigned int reserverd:4;
        u8 port;
} __attribute__ ((packed));

/* This stores all control uplink flags */
struct ctrl_ul {
        unsigned int DTR:1;
        unsigned int RTS:1;
        unsigned int reserved:6;
        u8 port;
} __attribute__ ((packed));
#endif

/* This holds all information that is needed regarding a port */
struct port {
        struct tty_port port;
        u8 update_flow_control;
        struct ctrl_ul ctrl_ul;
        struct ctrl_dl ctrl_dl;
        struct kfifo fifo_ul;
        void __iomem *dl_addr[2];
        u32 dl_size[2];
        u8 toggle_dl;
        void __iomem *ul_addr[2];
        u32 ul_size[2];
        u8 toggle_ul;
        u16 token_dl;

        wait_queue_head_t tty_wait;
        struct async_icount tty_icount;

        struct nozomi *dc;
};

/* Private data one for each card in the system */
struct nozomi {
        void __iomem *base_addr;
        unsigned long flip;

        /* Pointers to registers */
        void __iomem *reg_iir;
        void __iomem *reg_fcr;
        void __iomem *reg_ier;

        u16 last_ier;
        enum card_type card_type;
        struct config_table config_table;       /* Configuration table */
        struct pci_dev *pdev;
        struct port port[NOZOMI_MAX_PORTS];
        u8 *send_buf;

        spinlock_t spin_mutex;  /* secures access to registers and tty */

        unsigned int index_start;
        enum card_state state;
        u32 open_ttys;
};

/* This is a data packet that is read or written to/from card */
struct buffer {
        u32 size;               /* size is the length of the data buffer */
        u8 *data;
} __attribute__ ((packed));

/* Global variables */
static const struct pci_device_id nozomi_pci_tbl[] = {
        {PCI_DEVICE(0x1931, 0x000c)},   /* Nozomi HSDPA */
        {},
};

MODULE_DEVICE_TABLE(pci, nozomi_pci_tbl);

static struct nozomi *ndevs[NOZOMI_MAX_CARDS];
static struct tty_driver *ntty_driver;

static const struct tty_port_operations noz_tty_port_ops;

/*
 * find card by tty_index
 */
static inline struct nozomi *get_dc_by_tty(const struct tty_struct *tty)
{
        return tty ? ndevs[tty->index / MAX_PORT] : NULL;
}

static inline struct port *get_port_by_tty(const struct tty_struct *tty)
{
        struct nozomi *ndev = get_dc_by_tty(tty);
        return ndev ? &ndev->port[tty->index % MAX_PORT] : NULL;
}

/*
 * TODO:
 * -Optimize
 * -Rewrite cleaner
 */

static void read_mem32(u32 *buf, const void __iomem *mem_addr_start,
                        u32 size_bytes)
{
        u32 i = 0;
        const u32 __iomem *ptr = mem_addr_start;
        u16 *buf16;

        if (unlikely(!ptr || !buf))
                goto out;

        /* shortcut for extremely often used cases */
        switch (size_bytes) {
        case 2: /* 2 bytes */
                buf16 = (u16 *) buf;
                *buf16 = __le16_to_cpu(readw(ptr));
                goto out;
                break;
        case 4: /* 4 bytes */
                *(buf) = __le32_to_cpu(readl(ptr));
                goto out;
                break;
        }

        while (i < size_bytes) {
                if (size_bytes - i == 2) {
                        /* Handle 2 bytes in the end */
                        buf16 = (u16 *) buf;
                        *(buf16) = __le16_to_cpu(readw(ptr));
                        i += 2;
                } else {
                        /* Read 4 bytes */
                        *(buf) = __le32_to_cpu(readl(ptr));
                        i += 4;
                }
                buf++;
                ptr++;
        }
out:
        return;
}

/*
 * TODO:
 * -Optimize
 * -Rewrite cleaner
 */
static u32 write_mem32(void __iomem *mem_addr_start, const u32 *buf,
                        u32 size_bytes)
{
        u32 i = 0;
        u32 __iomem *ptr = mem_addr_start;
        const u16 *buf16;

        if (unlikely(!ptr || !buf))
                return 0;

        /* shortcut for extremely often used cases */
        switch (size_bytes) {
        case 2: /* 2 bytes */
                buf16 = (const u16 *)buf;
                writew(__cpu_to_le16(*buf16), ptr);
                return 2;
                break;
        case 1: /*
                 * also needs to write 4 bytes in this case
                 * so falling through..
                 */
        case 4: /* 4 bytes */
                writel(__cpu_to_le32(*buf), ptr);
                return 4;
                break;
        }

        while (i < size_bytes) {
                if (size_bytes - i == 2) {
                        /* 2 bytes */
                        buf16 = (const u16 *)buf;
                        writew(__cpu_to_le16(*buf16), ptr);
                        i += 2;
                } else {
                        /* 4 bytes */
                        writel(__cpu_to_le32(*buf), ptr);
                        i += 4;
                }
                buf++;
                ptr++;
        }
        return i;
}

/* Setup pointers to different channels and also setup buffer sizes. */
static void nozomi_setup_memory(struct nozomi *dc)
{
        void __iomem *offset = dc->base_addr + dc->config_table.dl_start;
        /* The length reported is including the length field of 4 bytes,
         * hence subtract with 4.
         */
        const u16 buff_offset = 4;

        /* Modem port dl configuration */
        dc->port[PORT_MDM].dl_addr[CH_A] = offset;
        dc->port[PORT_MDM].dl_addr[CH_B] =
                                (offset += dc->config_table.dl_mdm_len1);
        dc->port[PORT_MDM].dl_size[CH_A] =
                                dc->config_table.dl_mdm_len1 - buff_offset;
        dc->port[PORT_MDM].dl_size[CH_B] =
                                dc->config_table.dl_mdm_len2 - buff_offset;

        /* Diag port dl configuration */
        dc->port[PORT_DIAG].dl_addr[CH_A] =
                                (offset += dc->config_table.dl_mdm_len2);
        dc->port[PORT_DIAG].dl_size[CH_A] =
                                dc->config_table.dl_diag_len1 - buff_offset;
        dc->port[PORT_DIAG].dl_addr[CH_B] =
                                (offset += dc->config_table.dl_diag_len1);
        dc->port[PORT_DIAG].dl_size[CH_B] =
                                dc->config_table.dl_diag_len2 - buff_offset;

        /* App1 port dl configuration */
        dc->port[PORT_APP1].dl_addr[CH_A] =
                                (offset += dc->config_table.dl_diag_len2);
        dc->port[PORT_APP1].dl_size[CH_A] =
                                dc->config_table.dl_app1_len - buff_offset;

        /* App2 port dl configuration */
        dc->port[PORT_APP2].dl_addr[CH_A] =
                                (offset += dc->config_table.dl_app1_len);
        dc->port[PORT_APP2].dl_size[CH_A] =
                                dc->config_table.dl_app2_len - buff_offset;

        /* Ctrl dl configuration */
        dc->port[PORT_CTRL].dl_addr[CH_A] =
                                (offset += dc->config_table.dl_app2_len);
        dc->port[PORT_CTRL].dl_size[CH_A] =
                                dc->config_table.dl_ctrl_len - buff_offset;

        offset = dc->base_addr + dc->config_table.ul_start;

        /* Modem Port ul configuration */
        dc->port[PORT_MDM].ul_addr[CH_A] = offset;
        dc->port[PORT_MDM].ul_size[CH_A] =
                                dc->config_table.ul_mdm_len1 - buff_offset;
        dc->port[PORT_MDM].ul_addr[CH_B] =
                                (offset += dc->config_table.ul_mdm_len1);
        dc->port[PORT_MDM].ul_size[CH_B] =
                                dc->config_table.ul_mdm_len2 - buff_offset;

        /* Diag port ul configuration */
        dc->port[PORT_DIAG].ul_addr[CH_A] =
                                (offset += dc->config_table.ul_mdm_len2);
        dc->port[PORT_DIAG].ul_size[CH_A] =
                                dc->config_table.ul_diag_len - buff_offset;

        /* App1 port ul configuration */
        dc->port[PORT_APP1].ul_addr[CH_A] =
                                (offset += dc->config_table.ul_diag_len);
        dc->port[PORT_APP1].ul_size[CH_A] =
                                dc->config_table.ul_app1_len - buff_offset;

        /* App2 port ul configuration */
        dc->port[PORT_APP2].ul_addr[CH_A] =
                                (offset += dc->config_table.ul_app1_len);
        dc->port[PORT_APP2].ul_size[CH_A] =
                                dc->config_table.ul_app2_len - buff_offset;

        /* Ctrl ul configuration */
        dc->port[PORT_CTRL].ul_addr[CH_A] =
                                (offset += dc->config_table.ul_app2_len);
        dc->port[PORT_CTRL].ul_size[CH_A] =
                                dc->config_table.ul_ctrl_len - buff_offset;
}

/* Dump config table under initalization phase */
#ifdef DEBUG
static void dump_table(const struct nozomi *dc)
{
        DBG3("signature: 0x%08X", dc->config_table.signature);
        DBG3("version: 0x%04X", dc->config_table.version);
        DBG3("product_information: 0x%04X", \
                                dc->config_table.product_information);
        DBG3("toggle enabled: %d", dc->config_table.toggle.enabled);
        DBG3("toggle up_mdm: %d", dc->config_table.toggle.mdm_ul);
        DBG3("toggle dl_mdm: %d", dc->config_table.toggle.mdm_dl);
        DBG3("toggle dl_dbg: %d", dc->config_table.toggle.diag_dl);

        DBG3("dl_start: 0x%04X", dc->config_table.dl_start);
        DBG3("dl_mdm_len0: 0x%04X, %d", dc->config_table.dl_mdm_len1,
           dc->config_table.dl_mdm_len1);
        DBG3("dl_mdm_len1: 0x%04X, %d", dc->config_table.dl_mdm_len2,
           dc->config_table.dl_mdm_len2);
        DBG3("dl_diag_len0: 0x%04X, %d", dc->config_table.dl_diag_len1,
           dc->config_table.dl_diag_len1);
        DBG3("dl_diag_len1: 0x%04X, %d", dc->config_table.dl_diag_len2,
           dc->config_table.dl_diag_len2);
        DBG3("dl_app1_len: 0x%04X, %d", dc->config_table.dl_app1_len,
           dc->config_table.dl_app1_len);
        DBG3("dl_app2_len: 0x%04X, %d", dc->config_table.dl_app2_len,
           dc->config_table.dl_app2_len);
        DBG3("dl_ctrl_len: 0x%04X, %d", dc->config_table.dl_ctrl_len,
           dc->config_table.dl_ctrl_len);
        DBG3("ul_start: 0x%04X, %d", dc->config_table.ul_start,
           dc->config_table.ul_start);
        DBG3("ul_mdm_len[0]: 0x%04X, %d", dc->config_table.ul_mdm_len1,
           dc->config_table.ul_mdm_len1);
        DBG3("ul_mdm_len[1]: 0x%04X, %d", dc->config_table.ul_mdm_len2,
           dc->config_table.ul_mdm_len2);
        DBG3("ul_diag_len: 0x%04X, %d", dc->config_table.ul_diag_len,
           dc->config_table.ul_diag_len);
        DBG3("ul_app1_len: 0x%04X, %d", dc->config_table.ul_app1_len,
           dc->config_table.ul_app1_len);
        DBG3("ul_app2_len: 0x%04X, %d", dc->config_table.ul_app2_len,
           dc->config_table.ul_app2_len);
        DBG3("ul_ctrl_len: 0x%04X, %d", dc->config_table.ul_ctrl_len,
           dc->config_table.ul_ctrl_len);
}
#else
static inline void dump_table(const struct nozomi *dc) { }
#endif

/*
 * Read configuration table from card under intalization phase
 * Returns 1 if ok, else 0
 */
static int nozomi_read_config_table(struct nozomi *dc)
{
        read_mem32((u32 *) &dc->config_table, dc->base_addr + 0,
                                                sizeof(struct config_table));

        if (dc->config_table.signature != NOZOMI_CONFIG_MAGIC) {
                dev_err(&dc->pdev->dev, "ConfigTable Bad! 0x%08X != 0x%08X\n",
                        dc->config_table.signature, NOZOMI_CONFIG_MAGIC);
                return 0;
        }

        if ((dc->config_table.version == 0)
            || (dc->config_table.toggle.enabled == TOGGLE_VALID)) {
                int i;
                DBG1("Second phase, configuring card");

                nozomi_setup_memory(dc);

                dc->port[PORT_MDM].toggle_ul = dc->config_table.toggle.mdm_ul;
                dc->port[PORT_MDM].toggle_dl = dc->config_table.toggle.mdm_dl;
                dc->port[PORT_DIAG].toggle_dl = dc->config_table.toggle.diag_dl;
                DBG1("toggle ports: MDM UL:%d MDM DL:%d, DIAG DL:%d",
                   dc->port[PORT_MDM].toggle_ul,
                   dc->port[PORT_MDM].toggle_dl, dc->port[PORT_DIAG].toggle_dl);

                dump_table(dc);

                for (i = PORT_MDM; i < MAX_PORT; i++) {
                        memset(&dc->port[i].ctrl_dl, 0, sizeof(struct ctrl_dl));
                        memset(&dc->port[i].ctrl_ul, 0, sizeof(struct ctrl_ul));
                }

                /* Enable control channel */
                dc->last_ier = dc->last_ier | CTRL_DL;
                writew(dc->last_ier, dc->reg_ier);

                dc->state = NOZOMI_STATE_ALLOCATED;
                dev_info(&dc->pdev->dev, "Initialization OK!\n");
                return 1;
        }

        if ((dc->config_table.version > 0)
            && (dc->config_table.toggle.enabled != TOGGLE_VALID)) {
                u32 offset = 0;
                DBG1("First phase: pushing upload buffers, clearing download");

                dev_info(&dc->pdev->dev, "Version of card: %d\n",
                         dc->config_table.version);

                /* Here we should disable all I/O over F32. */
                nozomi_setup_memory(dc);

                /*
                 * We should send ALL channel pair tokens back along
                 * with reset token
                 */

                /* push upload modem buffers */
                write_mem32(dc->port[PORT_MDM].ul_addr[CH_A],
                        (u32 *) &offset, 4);
                write_mem32(dc->port[PORT_MDM].ul_addr[CH_B],
                        (u32 *) &offset, 4);

                writew(MDM_UL | DIAG_DL | MDM_DL, dc->reg_fcr);

                DBG1("First phase done");
        }

        return 1;
}

/* Enable uplink interrupts  */
static void enable_transmit_ul(enum port_type port, struct nozomi *dc)
{
        static const u16 mask[] = {MDM_UL, DIAG_UL, APP1_UL, APP2_UL, CTRL_UL};

        if (port < NOZOMI_MAX_PORTS) {
                dc->last_ier |= mask[port];
                writew(dc->last_ier, dc->reg_ier);
        } else {
                dev_err(&dc->pdev->dev, "Called with wrong port?\n");
        }
}

/* Disable uplink interrupts  */
static void disable_transmit_ul(enum port_type port, struct nozomi *dc)
{
        static const u16 mask[] =
                {~MDM_UL, ~DIAG_UL, ~APP1_UL, ~APP2_UL, ~CTRL_UL};

        if (port < NOZOMI_MAX_PORTS) {
                dc->last_ier &= mask[port];
                writew(dc->last_ier, dc->reg_ier);
        } else {
                dev_err(&dc->pdev->dev, "Called with wrong port?\n");
        }
}

/* Enable downlink interrupts */
static void enable_transmit_dl(enum port_type port, struct nozomi *dc)
{
        static const u16 mask[] = {MDM_DL, DIAG_DL, APP1_DL, APP2_DL, CTRL_DL};

        if (port < NOZOMI_MAX_PORTS) {
                dc->last_ier |= mask[port];
                writew(dc->last_ier, dc->reg_ier);
        } else {
                dev_err(&dc->pdev->dev, "Called with wrong port?\n");
        }
}

/* Disable downlink interrupts */
static void disable_transmit_dl(enum port_type port, struct nozomi *dc)
{
        static const u16 mask[] =
                {~MDM_DL, ~DIAG_DL, ~APP1_DL, ~APP2_DL, ~CTRL_DL};

        if (port < NOZOMI_MAX_PORTS) {
                dc->last_ier &= mask[port];
                writew(dc->last_ier, dc->reg_ier);
        } else {
                dev_err(&dc->pdev->dev, "Called with wrong port?\n");
        }
}

/*
 * Return 1 - send buffer to card and ack.
 * Return 0 - don't ack, don't send buffer to card.
 */
static int send_data(enum port_type index, struct nozomi *dc)
{
        u32 size = 0;
        struct port *port = &dc->port[index];
        const u8 toggle = port->toggle_ul;
        void __iomem *addr = port->ul_addr[toggle];
        const u32 ul_size = port->ul_size[toggle];

        /* Get data from tty and place in buf for now */
        size = kfifo_out(&port->fifo_ul, dc->send_buf,
                           ul_size < SEND_BUF_MAX ? ul_size : SEND_BUF_MAX);

        if (size == 0) {
                DBG4("No more data to send, disable link:");
                return 0;
        }

        /* DUMP(buf, size); */

        /* Write length + data */
        write_mem32(addr, (u32 *) &size, 4);
        write_mem32(addr + 4, (u32 *) dc->send_buf, size);

        tty_port_tty_wakeup(&port->port);

        return 1;
}

/* If all data has been read, return 1, else 0 */
static int receive_data(enum port_type index, struct nozomi *dc)
{
        u8 buf[RECEIVE_BUF_MAX] = { 0 };
        int size;
        u32 offset = 4;
        struct port *port = &dc->port[index];
        void __iomem *addr = port->dl_addr[port->toggle_dl];
        struct tty_struct *tty = tty_port_tty_get(&port->port);
        int i, ret;

        size = __le32_to_cpu(readl(addr));
        /*  DBG1( "%d bytes port: %d", size, index); */

        if (tty && tty_throttled(tty)) {
                DBG1("No room in tty, don't read data, don't ack interrupt, "
                        "disable interrupt");

                /* disable interrupt in downlink... */
                disable_transmit_dl(index, dc);
                ret = 0;
                goto put;
        }

        if (unlikely(size == 0)) {
                dev_err(&dc->pdev->dev, "size == 0?\n");
                ret = 1;
                goto put;
        }

        while (size > 0) {
                read_mem32((u32 *) buf, addr + offset, RECEIVE_BUF_MAX);

                if (size == 1) {
                        tty_insert_flip_char(&port->port, buf[0], TTY_NORMAL);
                        size = 0;
                } else if (size < RECEIVE_BUF_MAX) {
                        size -= tty_insert_flip_string(&port->port,
                                        (char *)buf, size);
                } else {
                        i = tty_insert_flip_string(&port->port,
                                        (char *)buf, RECEIVE_BUF_MAX);
                        size -= i;
                        offset += i;
                }
        }

        set_bit(index, &dc->flip);
        ret = 1;
put:
        tty_kref_put(tty);
        return ret;
}

/* Debug for interrupts */
#ifdef DEBUG
static char *interrupt2str(u16 interrupt)
{
        static char buf[TMP_BUF_MAX];
        char *p = buf;

        interrupt & MDM_DL1 ? p += snprintf(p, TMP_BUF_MAX, "MDM_DL1 ") : NULL;
        interrupt & MDM_DL2 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "MDM_DL2 ") : NULL;

        interrupt & MDM_UL1 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "MDM_UL1 ") : NULL;
        interrupt & MDM_UL2 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "MDM_UL2 ") : NULL;

        interrupt & DIAG_DL1 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "DIAG_DL1 ") : NULL;
        interrupt & DIAG_DL2 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "DIAG_DL2 ") : NULL;

        interrupt & DIAG_UL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "DIAG_UL ") : NULL;

        interrupt & APP1_DL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "APP1_DL ") : NULL;
        interrupt & APP2_DL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "APP2_DL ") : NULL;

        interrupt & APP1_UL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "APP1_UL ") : NULL;
        interrupt & APP2_UL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "APP2_UL ") : NULL;

        interrupt & CTRL_DL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "CTRL_DL ") : NULL;
        interrupt & CTRL_UL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "CTRL_UL ") : NULL;

        interrupt & RESET ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
                                        "RESET ") : NULL;

        return buf;
}
#endif

/*
 * Receive flow control
 * Return 1 - If ok, else 0
 */
static int receive_flow_control(struct nozomi *dc)
{
        enum port_type port = PORT_MDM;
        struct ctrl_dl ctrl_dl;
        struct ctrl_dl old_ctrl;
        u16 enable_ier = 0;

        read_mem32((u32 *) &ctrl_dl, dc->port[PORT_CTRL].dl_addr[CH_A], 2);

        switch (ctrl_dl.port) {
        case CTRL_CMD:
                DBG1("The Base Band sends this value as a response to a "
                        "request for IMSI detach sent over the control "
                        "channel uplink (see section 7.6.1).");
                break;
        case CTRL_MDM:
                port = PORT_MDM;
                enable_ier = MDM_DL;
                break;
        case CTRL_DIAG:
                port = PORT_DIAG;
                enable_ier = DIAG_DL;
                break;
        case CTRL_APP1:
                port = PORT_APP1;
                enable_ier = APP1_DL;
                break;
        case CTRL_APP2:
                port = PORT_APP2;
                enable_ier = APP2_DL;
                if (dc->state == NOZOMI_STATE_ALLOCATED) {
                        /*
                         * After card initialization the flow control
                         * received for APP2 is always the last
                         */
                        dc->state = NOZOMI_STATE_READY;
                        dev_info(&dc->pdev->dev, "Device READY!\n");
                }
                break;
        default:
                dev_err(&dc->pdev->dev,
                        "ERROR: flow control received for non-existing port\n");
                return 0;
        }

        DBG1("0x%04X->0x%04X", *((u16 *)&dc->port[port].ctrl_dl),
           *((u16 *)&ctrl_dl));

        old_ctrl = dc->port[port].ctrl_dl;
        dc->port[port].ctrl_dl = ctrl_dl;

        if (old_ctrl.CTS == 1 && ctrl_dl.CTS == 0) {
                DBG1("Disable interrupt (0x%04X) on port: %d",
                        enable_ier, port);
                disable_transmit_ul(port, dc);

        } else if (old_ctrl.CTS == 0 && ctrl_dl.CTS == 1) {

                if (kfifo_len(&dc->port[port].fifo_ul)) {
                        DBG1("Enable interrupt (0x%04X) on port: %d",
                                enable_ier, port);
                        DBG1("Data in buffer [%d], enable transmit! ",
                                kfifo_len(&dc->port[port].fifo_ul));
                        enable_transmit_ul(port, dc);
                } else {
                        DBG1("No data in buffer...");
                }
        }

        if (*(u16 *)&old_ctrl == *(u16 *)&ctrl_dl) {
                DBG1(" No change in mctrl");
                return 1;
        }
        /* Update statistics */
        if (old_ctrl.CTS != ctrl_dl.CTS)
                dc->port[port].tty_icount.cts++;
        if (old_ctrl.DSR != ctrl_dl.DSR)
                dc->port[port].tty_icount.dsr++;
        if (old_ctrl.RI != ctrl_dl.RI)
                dc->port[port].tty_icount.rng++;
        if (old_ctrl.DCD != ctrl_dl.DCD)
                dc->port[port].tty_icount.dcd++;

        wake_up_interruptible(&dc->port[port].tty_wait);

        DBG1("port: %d DCD(%d), CTS(%d), RI(%d), DSR(%d)",
           port,
           dc->port[port].tty_icount.dcd, dc->port[port].tty_icount.cts,
           dc->port[port].tty_icount.rng, dc->port[port].tty_icount.dsr);

        return 1;
}

static enum ctrl_port_type port2ctrl(enum port_type port,
                                        const struct nozomi *dc)
{
        switch (port) {
        case PORT_MDM:
                return CTRL_MDM;
        case PORT_DIAG:
                return CTRL_DIAG;
        case PORT_APP1:
                return CTRL_APP1;
        case PORT_APP2:
                return CTRL_APP2;
        default:
                dev_err(&dc->pdev->dev,
                        "ERROR: send flow control " \
                        "received for non-existing port\n");
        }
        return CTRL_ERROR;
}

/*
 * Send flow control, can only update one channel at a time
 * Return 0 - If we have updated all flow control

 * Return 1 - If we need to update more flow control, ack current enable more
 */
static int send_flow_control(struct nozomi *dc)
{
        u32 i, more_flow_control_to_be_updated = 0;
        u16 *ctrl;

        for (i = PORT_MDM; i < MAX_PORT; i++) {
                if (dc->port[i].update_flow_control) {
                        if (more_flow_control_to_be_updated) {
                                /* We have more flow control to be updated */
                                return 1;
                        }
                        dc->port[i].ctrl_ul.port = port2ctrl(i, dc);
                        ctrl = (u16 *)&dc->port[i].ctrl_ul;
                        write_mem32(dc->port[PORT_CTRL].ul_addr[0], \
                                (u32 *) ctrl, 2);
                        dc->port[i].update_flow_control = 0;
                        more_flow_control_to_be_updated = 1;
                }
        }
        return 0;
}

/*
 * Handle downlink data, ports that are handled are modem and diagnostics
 * Return 1 - ok
 * Return 0 - toggle fields are out of sync
 */
static int handle_data_dl(struct nozomi *dc, enum port_type port, u8 *toggle,
                        u16 read_iir, u16 mask1, u16 mask2)
{
        if (*toggle == 0 && read_iir & mask1) {
                if (receive_data(port, dc)) {
                        writew(mask1, dc->reg_fcr);
                        *toggle = !(*toggle);
                }

                if (read_iir & mask2) {
                        if (receive_data(port, dc)) {
                                writew(mask2, dc->reg_fcr);
                                *toggle = !(*toggle);
                        }
                }
        } else if (*toggle == 1 && read_iir & mask2) {
                if (receive_data(port, dc)) {
                        writew(mask2, dc->reg_fcr);
                        *toggle = !(*toggle);
                }

                if (read_iir & mask1) {
                        if (receive_data(port, dc)) {
                                writew(mask1, dc->reg_fcr);
                                *toggle = !(*toggle);
                        }
                }
        } else {
                dev_err(&dc->pdev->dev, "port out of sync!, toggle:%d\n",
                        *toggle);
                return 0;
        }
        return 1;
}

/*
 * Handle uplink data, this is currently for the modem port
 * Return 1 - ok
 * Return 0 - toggle field are out of sync
 */
static int handle_data_ul(struct nozomi *dc, enum port_type port, u16 read_iir)
{
        u8 *toggle = &(dc->port[port].toggle_ul);

        if (*toggle == 0 && read_iir & MDM_UL1) {
                dc->last_ier &= ~MDM_UL;
                writew(dc->last_ier, dc->reg_ier);
                if (send_data(port, dc)) {
                        writew(MDM_UL1, dc->reg_fcr);
                        dc->last_ier = dc->last_ier | MDM_UL;
                        writew(dc->last_ier, dc->reg_ier);
                        *toggle = !*toggle;
                }

                if (read_iir & MDM_UL2) {
                        dc->last_ier &= ~MDM_UL;
                        writew(dc->last_ier, dc->reg_ier);
                        if (send_data(port, dc)) {
                                writew(MDM_UL2, dc->reg_fcr);
                                dc->last_ier = dc->last_ier | MDM_UL;
                                writew(dc->last_ier, dc->reg_ier);
                                *toggle = !*toggle;
                        }
                }

        } else if (*toggle == 1 && read_iir & MDM_UL2) {
                dc->last_ier &= ~MDM_UL;
                writew(dc->last_ier, dc->reg_ier);
                if (send_data(port, dc)) {
                        writew(MDM_UL2, dc->reg_fcr);
                        dc->last_ier = dc->last_ier | MDM_UL;
                        writew(dc->last_ier, dc->reg_ier);
                        *toggle = !*toggle;
                }

                if (read_iir & MDM_UL1) {
                        dc->last_ier &= ~MDM_UL;
                        writew(dc->last_ier, dc->reg_ier);
                        if (send_data(port, dc)) {
                                writew(MDM_UL1, dc->reg_fcr);
                                dc->last_ier = dc->last_ier | MDM_UL;
                                writew(dc->last_ier, dc->reg_ier);
                                *toggle = !*toggle;
                        }
                }
        } else {
                writew(read_iir & MDM_UL, dc->reg_fcr);
                dev_err(&dc->pdev->dev, "port out of sync!\n");
                return 0;
        }
        return 1;
}

static irqreturn_t interrupt_handler(int irq, void *dev_id)
{
        struct nozomi *dc = dev_id;
        unsigned int a;
        u16 read_iir;

        if (!dc)
                return IRQ_NONE;

        spin_lock(&dc->spin_mutex);
        read_iir = readw(dc->reg_iir);

        /* Card removed */
        if (read_iir == (u16)-1)
                goto none;
        /*
         * Just handle interrupt enabled in IER
         * (by masking with dc->last_ier)
         */
        read_iir &= dc->last_ier;

        if (read_iir == 0)
                goto none;


        DBG4("%s irq:0x%04X, prev:0x%04X", interrupt2str(read_iir), read_iir,
                dc->last_ier);

        if (read_iir & RESET) {
                if (unlikely(!nozomi_read_config_table(dc))) {
                        dc->last_ier = 0x0;
                        writew(dc->last_ier, dc->reg_ier);
                        dev_err(&dc->pdev->dev, "Could not read status from "
                                "card, we should disable interface\n");
                } else {
                        writew(RESET, dc->reg_fcr);
                }
                /* No more useful info if this was the reset interrupt. */
                goto exit_handler;
        }
        if (read_iir & CTRL_UL) {
                DBG1("CTRL_UL");
                dc->last_ier &= ~CTRL_UL;
                writew(dc->last_ier, dc->reg_ier);
                if (send_flow_control(dc)) {
                        writew(CTRL_UL, dc->reg_fcr);
                        dc->last_ier = dc->last_ier | CTRL_UL;
                        writew(dc->last_ier, dc->reg_ier);
                }
        }
        if (read_iir & CTRL_DL) {
                receive_flow_control(dc);
                writew(CTRL_DL, dc->reg_fcr);
        }
        if (read_iir & MDM_DL) {
                if (!handle_data_dl(dc, PORT_MDM,
                                &(dc->port[PORT_MDM].toggle_dl), read_iir,
                                MDM_DL1, MDM_DL2)) {
                        dev_err(&dc->pdev->dev, "MDM_DL out of sync!\n");
                        goto exit_handler;
                }
        }
        if (read_iir & MDM_UL) {
                if (!handle_data_ul(dc, PORT_MDM, read_iir)) {
                        dev_err(&dc->pdev->dev, "MDM_UL out of sync!\n");
                        goto exit_handler;
                }
        }
        if (read_iir & DIAG_DL) {
                if (!handle_data_dl(dc, PORT_DIAG,
                                &(dc->port[PORT_DIAG].toggle_dl), read_iir,
                                DIAG_DL1, DIAG_DL2)) {
                        dev_err(&dc->pdev->dev, "DIAG_DL out of sync!\n");
                        goto exit_handler;
                }
        }
        if (read_iir & DIAG_UL) {
                dc->last_ier &= ~DIAG_UL;
                writew(dc->last_ier, dc->reg_ier);
                if (send_data(PORT_DIAG, dc)) {
                        writew(DIAG_UL, dc->reg_fcr);
                        dc->last_ier = dc->last_ier | DIAG_UL;
                        writew(dc->last_ier, dc->reg_ier);
                }
        }
        if (read_iir & APP1_DL) {
                if (receive_data(PORT_APP1, dc))
                        writew(APP1_DL, dc->reg_fcr);
        }
        if (read_iir & APP1_UL) {
                dc->last_ier &= ~APP1_UL;
                writew(dc->last_ier, dc->reg_ier);
                if (send_data(PORT_APP1, dc)) {
                        writew(APP1_UL, dc->reg_fcr);
                        dc->last_ier = dc->last_ier | APP1_UL;
                        writew(dc->last_ier, dc->reg_ier);
                }
        }
        if (read_iir & APP2_DL) {
                if (receive_data(PORT_APP2, dc))
                        writew(APP2_DL, dc->reg_fcr);
        }
        if (read_iir & APP2_UL) {
                dc->last_ier &= ~APP2_UL;
                writew(dc->last_ier, dc->reg_ier);
                if (send_data(PORT_APP2, dc)) {
                        writew(APP2_UL, dc->reg_fcr);
                        dc->last_ier = dc->last_ier | APP2_UL;
                        writew(dc->last_ier, dc->reg_ier);
                }
        }

exit_handler:
        spin_unlock(&dc->spin_mutex);

        for (a = 0; a < NOZOMI_MAX_PORTS; a++)
                if (test_and_clear_bit(a, &dc->flip))
                        tty_flip_buffer_push(&dc->port[a].port);

        return IRQ_HANDLED;
none:
        spin_unlock(&dc->spin_mutex);
        return IRQ_NONE;
}

static void nozomi_get_card_type(struct nozomi *dc)
{
        int i;
        u32 size = 0;

        for (i = 0; i < 6; i++)
                size += pci_resource_len(dc->pdev, i);

        /* Assume card type F32_8 if no match */
        dc->card_type = size == 2048 ? F32_2 : F32_8;

        dev_info(&dc->pdev->dev, "Card type is: %d\n", dc->card_type);
}

static void nozomi_setup_private_data(struct nozomi *dc)
{
        void __iomem *offset = dc->base_addr + dc->card_type / 2;
        unsigned int i;

        dc->reg_fcr = (void __iomem *)(offset + R_FCR);
        dc->reg_iir = (void __iomem *)(offset + R_IIR);
        dc->reg_ier = (void __iomem *)(offset + R_IER);
        dc->last_ier = 0;
        dc->flip = 0;

        dc->port[PORT_MDM].token_dl = MDM_DL;
        dc->port[PORT_DIAG].token_dl = DIAG_DL;
        dc->port[PORT_APP1].token_dl = APP1_DL;
        dc->port[PORT_APP2].token_dl = APP2_DL;

        for (i = 0; i < MAX_PORT; i++)
                init_waitqueue_head(&dc->port[i].tty_wait);
}

static ssize_t card_type_show(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        const struct nozomi *dc = pci_get_drvdata(to_pci_dev(dev));

        return sprintf(buf, "%d\n", dc->card_type);
}
static DEVICE_ATTR_RO(card_type);

static ssize_t open_ttys_show(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        const struct nozomi *dc = pci_get_drvdata(to_pci_dev(dev));

        return sprintf(buf, "%u\n", dc->open_ttys);
}
static DEVICE_ATTR_RO(open_ttys);

static void make_sysfs_files(struct nozomi *dc)
{
        if (device_create_file(&dc->pdev->dev, &dev_attr_card_type))
                dev_err(&dc->pdev->dev,
                        "Could not create sysfs file for card_type\n");
        if (device_create_file(&dc->pdev->dev, &dev_attr_open_ttys))
                dev_err(&dc->pdev->dev,
                        "Could not create sysfs file for open_ttys\n");
}

static void remove_sysfs_files(struct nozomi *dc)
{
        device_remove_file(&dc->pdev->dev, &dev_attr_card_type);
        device_remove_file(&dc->pdev->dev, &dev_attr_open_ttys);
}

/* Allocate memory for one device */
static int nozomi_card_init(struct pci_dev *pdev,
                                      const struct pci_device_id *ent)
{
        int ret;
        struct nozomi *dc = NULL;
        int ndev_idx;
        int i;

        dev_dbg(&pdev->dev, "Init, new card found\n");

        for (ndev_idx = 0; ndev_idx < ARRAY_SIZE(ndevs); ndev_idx++)
                if (!ndevs[ndev_idx])
                        break;

        if (ndev_idx >= ARRAY_SIZE(ndevs)) {
                dev_err(&pdev->dev, "no free tty range for this card left\n");
                ret = -EIO;
                goto err;
        }

        dc = kzalloc(sizeof(struct nozomi), GFP_KERNEL);
        if (unlikely(!dc)) {
                dev_err(&pdev->dev, "Could not allocate memory\n");
                ret = -ENOMEM;
                goto err_free;
        }

        dc->pdev = pdev;

        ret = pci_enable_device(dc->pdev);
        if (ret) {
                dev_err(&pdev->dev, "Failed to enable PCI Device\n");
                goto err_free;
        }

        ret = pci_request_regions(dc->pdev, NOZOMI_NAME);
        if (ret) {
                dev_err(&pdev->dev, "I/O address 0x%04x already in use\n",
                        (int) /* nozomi_private.io_addr */ 0);
                goto err_disable_device;
        }

        /* Find out what card type it is */
        nozomi_get_card_type(dc);

        dc->base_addr = pci_iomap(dc->pdev, 0, dc->card_type);
        if (!dc->base_addr) {
                dev_err(&pdev->dev, "Unable to map card MMIO\n");
                ret = -ENODEV;
                goto err_rel_regs;
        }

        dc->send_buf = kmalloc(SEND_BUF_MAX, GFP_KERNEL);
        if (!dc->send_buf) {
                dev_err(&pdev->dev, "Could not allocate send buffer?\n");
                ret = -ENOMEM;
                goto err_free_sbuf;
        }

        for (i = PORT_MDM; i < MAX_PORT; i++) {
                if (kfifo_alloc(&dc->port[i].fifo_ul, FIFO_BUFFER_SIZE_UL,
                                        GFP_KERNEL)) {
                        dev_err(&pdev->dev,
                                        "Could not allocate kfifo buffer\n");
                        ret = -ENOMEM;
                        goto err_free_kfifo;
                }
        }

        spin_lock_init(&dc->spin_mutex);

        nozomi_setup_private_data(dc);

        /* Disable all interrupts */
        dc->last_ier = 0;
        writew(dc->last_ier, dc->reg_ier);

        ret = request_irq(pdev->irq, &interrupt_handler, IRQF_SHARED,
                        NOZOMI_NAME, dc);
        if (unlikely(ret)) {
                dev_err(&pdev->dev, "can't request irq %d\n", pdev->irq);
                goto err_free_kfifo;
        }

        DBG1("base_addr: %p", dc->base_addr);

        make_sysfs_files(dc);

        dc->index_start = ndev_idx * MAX_PORT;
        ndevs[ndev_idx] = dc;

        pci_set_drvdata(pdev, dc);

        /* Enable RESET interrupt */
        dc->last_ier = RESET;
        iowrite16(dc->last_ier, dc->reg_ier);

        dc->state = NOZOMI_STATE_ENABLED;

        for (i = 0; i < MAX_PORT; i++) {
                struct device *tty_dev;
                struct port *port = &dc->port[i];
                port->dc = dc;
                tty_port_init(&port->port);
                port->port.ops = &noz_tty_port_ops;
                tty_dev = tty_port_register_device(&port->port, ntty_driver,
                                dc->index_start + i, &pdev->dev);

                if (IS_ERR(tty_dev)) {
                        ret = PTR_ERR(tty_dev);
                        dev_err(&pdev->dev, "Could not allocate tty?\n");
                        tty_port_destroy(&port->port);
                        goto err_free_tty;
                }
        }

        return 0;

err_free_tty:
        for (i = 0; i < MAX_PORT; ++i) {
                tty_unregister_device(ntty_driver, dc->index_start + i);
                tty_port_destroy(&dc->port[i].port);
        }
err_free_kfifo:
        for (i = 0; i < MAX_PORT; i++)
                kfifo_free(&dc->port[i].fifo_ul);
err_free_sbuf:
        kfree(dc->send_buf);
        iounmap(dc->base_addr);
err_rel_regs:
        pci_release_regions(pdev);
err_disable_device:
        pci_disable_device(pdev);
err_free:
        kfree(dc);
err:
        return ret;
}

static void tty_exit(struct nozomi *dc)
{
        unsigned int i;

        DBG1(" ");

        for (i = 0; i < MAX_PORT; ++i)
                tty_port_tty_hangup(&dc->port[i].port, false);

        /* Racy below - surely should wait for scheduled work to be done or
           complete off a hangup method ? */
        while (dc->open_ttys)
                msleep(1);
        for (i = 0; i < MAX_PORT; ++i) {
                tty_unregister_device(ntty_driver, dc->index_start + i);
                tty_port_destroy(&dc->port[i].port);
        }
}

/* Deallocate memory for one device */
static void nozomi_card_exit(struct pci_dev *pdev)
{
        int i;
        struct ctrl_ul ctrl;
        struct nozomi *dc = pci_get_drvdata(pdev);

        /* Disable all interrupts */
        dc->last_ier = 0;
        writew(dc->last_ier, dc->reg_ier);

        tty_exit(dc);

        /* Send 0x0001, command card to resend the reset token.  */
        /* This is to get the reset when the module is reloaded. */
        ctrl.port = 0x00;
        ctrl.reserved = 0;
        ctrl.RTS = 0;
        ctrl.DTR = 1;
        DBG1("sending flow control 0x%04X", *((u16 *)&ctrl));

        /* Setup dc->reg addresses to we can use defines here */
        write_mem32(dc->port[PORT_CTRL].ul_addr[0], (u32 *)&ctrl, 2);
        writew(CTRL_UL, dc->reg_fcr);   /* push the token to the card. */

        remove_sysfs_files(dc);

        free_irq(pdev->irq, dc);

        for (i = 0; i < MAX_PORT; i++)
                kfifo_free(&dc->port[i].fifo_ul);

        kfree(dc->send_buf);

        iounmap(dc->base_addr);

        pci_release_regions(pdev);

        pci_disable_device(pdev);

        ndevs[dc->index_start / MAX_PORT] = NULL;

        kfree(dc);
}

static void set_rts(const struct tty_struct *tty, int rts)
{
        struct port *port = get_port_by_tty(tty);

        port->ctrl_ul.RTS = rts;
        port->update_flow_control = 1;
        enable_transmit_ul(PORT_CTRL, get_dc_by_tty(tty));
}

static void set_dtr(const struct tty_struct *tty, int dtr)
{
        struct port *port = get_port_by_tty(tty);

        DBG1("SETTING DTR index: %d, dtr: %d", tty->index, dtr);

        port->ctrl_ul.DTR = dtr;
        port->update_flow_control = 1;
        enable_transmit_ul(PORT_CTRL, get_dc_by_tty(tty));
}

/*
 * ----------------------------------------------------------------------------
 * TTY code
 * ----------------------------------------------------------------------------
 */

static int ntty_install(struct tty_driver *driver, struct tty_struct *tty)
{
        struct port *port = get_port_by_tty(tty);
        struct nozomi *dc = get_dc_by_tty(tty);
        int ret;
        if (!port || !dc || dc->state != NOZOMI_STATE_READY)
                return -ENODEV;
        ret = tty_standard_install(driver, tty);
        if (ret == 0)
                tty->driver_data = port;
        return ret;
}

static void ntty_cleanup(struct tty_struct *tty)
{
        tty->driver_data = NULL;
}

static int ntty_activate(struct tty_port *tport, struct tty_struct *tty)
{
        struct port *port = container_of(tport, struct port, port);
        struct nozomi *dc = port->dc;
        unsigned long flags;

        DBG1("open: %d", port->token_dl);
        spin_lock_irqsave(&dc->spin_mutex, flags);
        dc->last_ier = dc->last_ier | port->token_dl;
        writew(dc->last_ier, dc->reg_ier);
        dc->open_ttys++;
        spin_unlock_irqrestore(&dc->spin_mutex, flags);
        printk("noz: activated %d: %p\n", tty->index, tport);
        return 0;
}

static int ntty_open(struct tty_struct *tty, struct file *filp)
{
        struct port *port = tty->driver_data;
        return tty_port_open(&port->port, tty, filp);
}

static void ntty_shutdown(struct tty_port *tport)
{
        struct port *port = container_of(tport, struct port, port);
        struct nozomi *dc = port->dc;
        unsigned long flags;

        DBG1("close: %d", port->token_dl);
        spin_lock_irqsave(&dc->spin_mutex, flags);
        dc->last_ier &= ~(port->token_dl);
        writew(dc->last_ier, dc->reg_ier);
        dc->open_ttys--;
        spin_unlock_irqrestore(&dc->spin_mutex, flags);
        printk("noz: shutdown %p\n", tport);
}

static void ntty_close(struct tty_struct *tty, struct file *filp)
{
        struct port *port = tty->driver_data;
        if (port)
                tty_port_close(&port->port, tty, filp);
}

static void ntty_hangup(struct tty_struct *tty)
{
        struct port *port = tty->driver_data;
        tty_port_hangup(&port->port);
}

/*
 * called when the userspace process writes to the tty (/dev/noz*).
 * Data is inserted into a fifo, which is then read and transferred to the modem.
 */
static int ntty_write(struct tty_struct *tty, const unsigned char *buffer,
                      int count)
{
        int rval = -EINVAL;
        struct nozomi *dc = get_dc_by_tty(tty);
        struct port *port = tty->driver_data;
        unsigned long flags;

        /* DBG1( "WRITEx: %d, index = %d", count, index); */

        if (!dc || !port)
                return -ENODEV;

        rval = kfifo_in(&port->fifo_ul, (unsigned char *)buffer, count);

        spin_lock_irqsave(&dc->spin_mutex, flags);
        /* CTS is only valid on the modem channel */
        if (port == &(dc->port[PORT_MDM])) {
                if (port->ctrl_dl.CTS) {
                        DBG4("Enable interrupt");
                        enable_transmit_ul(tty->index % MAX_PORT, dc);
                } else {
                        dev_err(&dc->pdev->dev,
                                "CTS not active on modem port?\n");
                }
        } else {
                enable_transmit_ul(tty->index % MAX_PORT, dc);
        }
        spin_unlock_irqrestore(&dc->spin_mutex, flags);

        return rval;
}

/*
 * Calculate how much is left in device
 * This method is called by the upper tty layer.
 *   #according to sources N_TTY.c it expects a value >= 0 and
 *    does not check for negative values.
 *
 * If the port is unplugged report lots of room and let the bits
 * dribble away so we don't block anything.
 */
static int ntty_write_room(struct tty_struct *tty)
{
        struct port *port = tty->driver_data;
        int room = 4096;
        const struct nozomi *dc = get_dc_by_tty(tty);

        if (dc)
                room = kfifo_avail(&port->fifo_ul);

        return room;
}

/* Gets io control parameters */
static int ntty_tiocmget(struct tty_struct *tty)
{
        const struct port *port = tty->driver_data;
        const struct ctrl_dl *ctrl_dl = &port->ctrl_dl;
        const struct ctrl_ul *ctrl_ul = &port->ctrl_ul;

        /* Note: these could change under us but it is not clear this
           matters if so */
        return (ctrl_ul->RTS ? TIOCM_RTS : 0)
                | (ctrl_ul->DTR ? TIOCM_DTR : 0)
                | (ctrl_dl->DCD ? TIOCM_CAR : 0)
                | (ctrl_dl->RI  ? TIOCM_RNG : 0)
                | (ctrl_dl->DSR ? TIOCM_DSR : 0)
                | (ctrl_dl->CTS ? TIOCM_CTS : 0);
}

/* Sets io controls parameters */
static int ntty_tiocmset(struct tty_struct *tty,
                                        unsigned int set, unsigned int clear)
{
        struct nozomi *dc = get_dc_by_tty(tty);
        unsigned long flags;

        spin_lock_irqsave(&dc->spin_mutex, flags);
        if (set & TIOCM_RTS)
                set_rts(tty, 1);
        else if (clear & TIOCM_RTS)
                set_rts(tty, 0);

        if (set & TIOCM_DTR)
                set_dtr(tty, 1);
        else if (clear & TIOCM_DTR)
                set_dtr(tty, 0);
        spin_unlock_irqrestore(&dc->spin_mutex, flags);

        return 0;
}

static int ntty_cflags_changed(struct port *port, unsigned long flags,
                struct async_icount *cprev)
{
        const struct async_icount cnow = port->tty_icount;
        int ret;

        ret = ((flags & TIOCM_RNG) && (cnow.rng != cprev->rng))
                || ((flags & TIOCM_DSR) && (cnow.dsr != cprev->dsr))
                || ((flags & TIOCM_CD)  && (cnow.dcd != cprev->dcd))
                || ((flags & TIOCM_CTS) && (cnow.cts != cprev->cts));

        *cprev = cnow;

        return ret;
}

static int ntty_tiocgicount(struct tty_struct *tty,
                                struct serial_icounter_struct *icount)
{
        struct port *port = tty->driver_data;
        const struct async_icount cnow = port->tty_icount;

        icount->cts = cnow.cts;
        icount->dsr = cnow.dsr;
        icount->rng = cnow.rng;
        icount->dcd = cnow.dcd;
        icount->rx = cnow.rx;
        icount->tx = cnow.tx;
        icount->frame = cnow.frame;
        icount->overrun = cnow.overrun;
        icount->parity = cnow.parity;
        icount->brk = cnow.brk;
        icount->buf_overrun = cnow.buf_overrun;
        return 0;
}

static int ntty_ioctl(struct tty_struct *tty,
                      unsigned int cmd, unsigned long arg)
{
        struct port *port = tty->driver_data;
        int rval = -ENOIOCTLCMD;

        DBG1("******** IOCTL, cmd: %d", cmd);

        switch (cmd) {
        case TIOCMIWAIT: {
                struct async_icount cprev = port->tty_icount;

                rval = wait_event_interruptible(port->tty_wait,
                                ntty_cflags_changed(port, arg, &cprev));
                break;
        }
        default:
                DBG1("ERR: 0x%08X, %d", cmd, cmd);
                break;
        }

        return rval;
}

/*
 * Called by the upper tty layer when tty buffers are ready
 * to receive data again after a call to throttle.
 */
static void ntty_unthrottle(struct tty_struct *tty)
{
        struct nozomi *dc = get_dc_by_tty(tty);
        unsigned long flags;

        DBG1("UNTHROTTLE");
        spin_lock_irqsave(&dc->spin_mutex, flags);
        enable_transmit_dl(tty->index % MAX_PORT, dc);
        set_rts(tty, 1);

        spin_unlock_irqrestore(&dc->spin_mutex, flags);
}

/*
 * Called by the upper tty layer when the tty buffers are almost full.
 * The driver should stop send more data.
 */
static void ntty_throttle(struct tty_struct *tty)
{
        struct nozomi *dc = get_dc_by_tty(tty);
        unsigned long flags;

        DBG1("THROTTLE");
        spin_lock_irqsave(&dc->spin_mutex, flags);
        set_rts(tty, 0);
        spin_unlock_irqrestore(&dc->spin_mutex, flags);
}

/* Returns number of chars in buffer, called by tty layer */
static s32 ntty_chars_in_buffer(struct tty_struct *tty)
{
        struct port *port = tty->driver_data;
        struct nozomi *dc = get_dc_by_tty(tty);
        s32 rval = 0;

        if (unlikely(!dc || !port)) {
                goto exit_in_buffer;
        }

        rval = kfifo_len(&port->fifo_ul);

exit_in_buffer:
        return rval;
}

static const struct tty_port_operations noz_tty_port_ops = {
        .activate = ntty_activate,
        .shutdown = ntty_shutdown,
};

static const struct tty_operations tty_ops = {
        .ioctl = ntty_ioctl,
        .open = ntty_open,
        .close = ntty_close,
        .hangup = ntty_hangup,
        .write = ntty_write,
        .write_room = ntty_write_room,
        .unthrottle = ntty_unthrottle,
        .throttle = ntty_throttle,
        .chars_in_buffer = ntty_chars_in_buffer,
        .tiocmget = ntty_tiocmget,
        .tiocmset = ntty_tiocmset,
        .get_icount = ntty_tiocgicount,
        .install = ntty_install,
        .cleanup = ntty_cleanup,
};

/* Module initialization */
static struct pci_driver nozomi_driver = {
        .name = NOZOMI_NAME,
        .id_table = nozomi_pci_tbl,
        .probe = nozomi_card_init,
        .remove = nozomi_card_exit,
};

static __init int nozomi_init(void)
{
        int ret;

        printk(KERN_INFO "Initializing %s\n", VERSION_STRING);

        ntty_driver = alloc_tty_driver(NTTY_TTY_MAXMINORS);
        if (!ntty_driver)
                return -ENOMEM;

        ntty_driver->driver_name = NOZOMI_NAME_TTY;
        ntty_driver->name = "noz";
        ntty_driver->major = 0;
        ntty_driver->type = TTY_DRIVER_TYPE_SERIAL;
        ntty_driver->subtype = SERIAL_TYPE_NORMAL;
        ntty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
        ntty_driver->init_termios = tty_std_termios;
        ntty_driver->init_termios.c_cflag = B115200 | CS8 | CREAD | \
                                                HUPCL | CLOCAL;
        ntty_driver->init_termios.c_ispeed = 115200;
        ntty_driver->init_termios.c_ospeed = 115200;
        tty_set_operations(ntty_driver, &tty_ops);

        ret = tty_register_driver(ntty_driver);
        if (ret) {
                printk(KERN_ERR "Nozomi: failed to register ntty driver\n");
                goto free_tty;
        }

        ret = pci_register_driver(&nozomi_driver);
        if (ret) {
                printk(KERN_ERR "Nozomi: can't register pci driver\n");
                goto unr_tty;
        }

        return 0;
unr_tty:
        tty_unregister_driver(ntty_driver);
free_tty:
        put_tty_driver(ntty_driver);
        return ret;
}

static __exit void nozomi_exit(void)
{
        printk(KERN_INFO "Unloading %s\n", DRIVER_DESC);
        pci_unregister_driver(&nozomi_driver);
        tty_unregister_driver(ntty_driver);
        put_tty_driver(ntty_driver);
}

module_init(nozomi_init);
module_exit(nozomi_exit);

MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION(DRIVER_DESC);