// SPDX-License-Identifier: GPL-2.0-only
/*
 *  pti.c - PTI driver for cJTAG data extration
 *
 *  Copyright (C) Intel 2010
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * The PTI (Parallel Trace Interface) driver directs trace data routed from
 * various parts in the system out through the Intel Penwell PTI port and
 * out of the mobile device for analysis with a debugging tool
 * (Lauterbach, Fido). This is part of a solution for the MIPI P1149.7,
 * compact JTAG, standard.
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/pci.h>
#include <linux/mutex.h>
#include <linux/miscdevice.h>
#include <linux/intel-pti.h>
#include <linux/slab.h>
#include <linux/uaccess.h>

#define DRIVERNAME              "pti"
#define PCINAME                 "pciPTI"
#define TTYNAME                 "ttyPTI"
#define CHARNAME                "pti"
#define PTITTY_MINOR_START      0
#define PTITTY_MINOR_NUM        2
#define MAX_APP_IDS             16   /* 128 channel ids / u8 bit size */
#define MAX_OS_IDS              16   /* 128 channel ids / u8 bit size */
#define MAX_MODEM_IDS           16   /* 128 channel ids / u8 bit size */
#define MODEM_BASE_ID           71   /* modem master ID address    */
#define CONTROL_ID              72   /* control master ID address  */
#define CONSOLE_ID              73   /* console master ID address  */
#define OS_BASE_ID              74   /* base OS master ID address  */
#define APP_BASE_ID             80   /* base App master ID address */
#define CONTROL_FRAME_LEN       32   /* PTI control frame maximum size */
#define USER_COPY_SIZE          8192 /* 8Kb buffer for user space copy */
#define APERTURE_14             0x3800000 /* offset to first OS write addr */
#define APERTURE_LEN            0x400000  /* address length */

struct pti_tty {
        struct pti_masterchannel *mc;
};

struct pti_dev {
        struct tty_port port[PTITTY_MINOR_NUM];
        unsigned long pti_addr;
        unsigned long aperture_base;
        void __iomem *pti_ioaddr;
        u8 ia_app[MAX_APP_IDS];
        u8 ia_os[MAX_OS_IDS];
        u8 ia_modem[MAX_MODEM_IDS];
};

/*
 * This protects access to ia_app, ia_os, and ia_modem,
 * which keeps track of channels allocated in
 * an aperture write id.
 */
static DEFINE_MUTEX(alloclock);

static const struct pci_device_id pci_ids[] = {
                {PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x82B)},
                {0}
};

static struct tty_driver *pti_tty_driver;
static struct pti_dev *drv_data;

static unsigned int pti_console_channel;
static unsigned int pti_control_channel;

/**
 *  pti_write_to_aperture()- The private write function to PTI HW.
 *
 *  @mc: The 'aperture'. It's part of a write address that holds
 *       a master and channel ID.
 *  @buf: Data being written to the HW that will ultimately be seen
 *        in a debugging tool (Fido, Lauterbach).
 *  @len: Size of buffer.
 *
 *  Since each aperture is specified by a unique
 *  master/channel ID, no two processes will be writing
 *  to the same aperture at the same time so no lock is required. The
 *  PTI-Output agent will send these out in the order that they arrived, and
 *  thus, it will intermix these messages. The debug tool can then later
 *  regroup the appropriate message segments together reconstituting each
 *  message.
 */
static void pti_write_to_aperture(struct pti_masterchannel *mc,
                                  u8 *buf,
                                  int len)
{
        int dwordcnt;
        int final;
        int i;
        u32 ptiword;
        u32 __iomem *aperture;
        u8 *p = buf;

        /*
         * calculate the aperture offset from the base using the master and
         * channel id's.
         */
        aperture = drv_data->pti_ioaddr + (mc->master << 15)
                + (mc->channel << 8);

        dwordcnt = len >> 2;
        final = len - (dwordcnt << 2);      /* final = trailing bytes    */
        if (final == 0 && dwordcnt != 0) {  /* always need a final dword */
                final += 4;
                dwordcnt--;
        }

        for (i = 0; i < dwordcnt; i++) {
                ptiword = be32_to_cpu(*(u32 *)p);
                p += 4;
                iowrite32(ptiword, aperture);
        }

        aperture += PTI_LASTDWORD_DTS;  /* adding DTS signals that is EOM */

        ptiword = 0;
        for (i = 0; i < final; i++)
                ptiword |= *p++ << (24-(8*i));

        iowrite32(ptiword, aperture);
        return;
}

/**
 *  pti_control_frame_built_and_sent()- control frame build and send function.
 *
 *  @mc:          The master / channel structure on which the function
 *                built a control frame.
 *  @thread_name: The thread name associated with the master / channel or
 *                'NULL' if using the 'current' global variable.
 *
 *  To be able to post process the PTI contents on host side, a control frame
 *  is added before sending any PTI content. So the host side knows on
 *  each PTI frame the name of the thread using a dedicated master / channel.
 *  The thread name is retrieved from 'current' global variable if 'thread_name'
 *  is 'NULL', else it is retrieved from 'thread_name' parameter.
 *  This function builds this frame and sends it to a master ID CONTROL_ID.
 *  The overhead is only 32 bytes since the driver only writes to HW
 *  in 32 byte chunks.
 */
static void pti_control_frame_built_and_sent(struct pti_masterchannel *mc,
                                             const char *thread_name)
{
        /*
         * Since we access the comm member in current's task_struct, we only
         * need to be as large as what 'comm' in that structure is.
         */
        char comm[TASK_COMM_LEN];
        struct pti_masterchannel mccontrol = {.master = CONTROL_ID,
                                              .channel = 0};
        const char *thread_name_p;
        const char *control_format = "%3d %3d %s";
        u8 control_frame[CONTROL_FRAME_LEN];

        if (!thread_name) {
                if (!in_interrupt())
                        get_task_comm(comm, current);
                else
                        strncpy(comm, "Interrupt", TASK_COMM_LEN);

                /* Absolutely ensure our buffer is zero terminated. */
                comm[TASK_COMM_LEN-1] = 0;
                thread_name_p = comm;
        } else {
                thread_name_p = thread_name;
        }

        mccontrol.channel = pti_control_channel;
        pti_control_channel = (pti_control_channel + 1) & 0x7f;

        snprintf(control_frame, CONTROL_FRAME_LEN, control_format, mc->master,
                mc->channel, thread_name_p);
        pti_write_to_aperture(&mccontrol, control_frame, strlen(control_frame));
}

/**
 *  pti_write_full_frame_to_aperture()- high level function to
 *                                      write to PTI.
 *
 *  @mc:  The 'aperture'. It's part of a write address that holds
 *        a master and channel ID.
 *  @buf: Data being written to the HW that will ultimately be seen
 *        in a debugging tool (Fido, Lauterbach).
 *  @len: Size of buffer.
 *
 *  All threads sending data (either console, user space application, ...)
 *  are calling the high level function to write to PTI meaning that it is
 *  possible to add a control frame before sending the content.
 */
static void pti_write_full_frame_to_aperture(struct pti_masterchannel *mc,
                                                const unsigned char *buf,
                                                int len)
{
        pti_control_frame_built_and_sent(mc, NULL);
        pti_write_to_aperture(mc, (u8 *)buf, len);
}

/**
 * get_id()- Allocate a master and channel ID.
 *
 * @id_array:    an array of bits representing what channel
 *               id's are allocated for writing.
 * @max_ids:     The max amount of available write IDs to use.
 * @base_id:     The starting SW channel ID, based on the Intel
 *               PTI arch.
 * @thread_name: The thread name associated with the master / channel or
 *               'NULL' if using the 'current' global variable.
 *
 * Returns:
 *      pti_masterchannel struct with master, channel ID address
 *      0 for error
 *
 * Each bit in the arrays ia_app and ia_os correspond to a master and
 * channel id. The bit is one if the id is taken and 0 if free. For
 * every master there are 128 channel id's.
 */
static struct pti_masterchannel *get_id(u8 *id_array,
                                        int max_ids,
                                        int base_id,
                                        const char *thread_name)
{
        struct pti_masterchannel *mc;
        int i, j, mask;

        mc = kmalloc(sizeof(struct pti_masterchannel), GFP_KERNEL);
        if (mc == NULL)
                return NULL;

        /* look for a byte with a free bit */
        for (i = 0; i < max_ids; i++)
                if (id_array[i] != 0xff)
                        break;
        if (i == max_ids) {
                kfree(mc);
                return NULL;
        }
        /* find the bit in the 128 possible channel opportunities */
        mask = 0x80;
        for (j = 0; j < 8; j++) {
                if ((id_array[i] & mask) == 0)
                        break;
                mask >>= 1;
        }

        /* grab it */
        id_array[i] |= mask;
        mc->master  = base_id;
        mc->channel = ((i & 0xf)<<3) + j;
        /* write new master Id / channel Id allocation to channel control */
        pti_control_frame_built_and_sent(mc, thread_name);
        return mc;
}

/*
 * The following three functions:
 * pti_request_mastercahannel(), mipi_release_masterchannel()
 * and pti_writedata() are an API for other kernel drivers to
 * access PTI.
 */

/**
 * pti_request_masterchannel()- Kernel API function used to allocate
 *                              a master, channel ID address
 *                              to write to PTI HW.
 *
 * @type:        0- request Application  master, channel aperture ID
 *                  write address.
 *               1- request OS master, channel aperture ID write
 *                  address.
 *               2- request Modem master, channel aperture ID
 *                  write address.
 *               Other values, error.
 * @thread_name: The thread name associated with the master / channel or
 *               'NULL' if using the 'current' global variable.
 *
 * Returns:
 *      pti_masterchannel struct
 *      0 for error
 */
struct pti_masterchannel *pti_request_masterchannel(u8 type,
                                                    const char *thread_name)
{
        struct pti_masterchannel *mc;

        mutex_lock(&alloclock);

        switch (type) {

        case 0:
                mc = get_id(drv_data->ia_app, MAX_APP_IDS,
                            APP_BASE_ID, thread_name);
                break;

        case 1:
                mc = get_id(drv_data->ia_os, MAX_OS_IDS,
                            OS_BASE_ID, thread_name);
                break;

        case 2:
                mc = get_id(drv_data->ia_modem, MAX_MODEM_IDS,
                            MODEM_BASE_ID, thread_name);
                break;
        default:
                mc = NULL;
        }

        mutex_unlock(&alloclock);
        return mc;
}
EXPORT_SYMBOL_GPL(pti_request_masterchannel);

/**
 * pti_release_masterchannel()- Kernel API function used to release
 *                              a master, channel ID address
 *                              used to write to PTI HW.
 *
 * @mc: master, channel apeture ID address to be released.  This
 *      will de-allocate the structure via kfree().
 */
void pti_release_masterchannel(struct pti_masterchannel *mc)
{
        u8 master, channel, i;

        mutex_lock(&alloclock);

        if (mc) {
                master = mc->master;
                channel = mc->channel;

                if (master == APP_BASE_ID) {
                        i = channel >> 3;
                        drv_data->ia_app[i] &=  ~(0x80>>(channel & 0x7));
                } else if (master == OS_BASE_ID) {
                        i = channel >> 3;
                        drv_data->ia_os[i] &= ~(0x80>>(channel & 0x7));
                } else {
                        i = channel >> 3;
                        drv_data->ia_modem[i] &= ~(0x80>>(channel & 0x7));
                }

                kfree(mc);
        }

        mutex_unlock(&alloclock);
}
EXPORT_SYMBOL_GPL(pti_release_masterchannel);

/**
 * pti_writedata()- Kernel API function used to write trace
 *                  debugging data to PTI HW.
 *
 * @mc:    Master, channel aperture ID address to write to.
 *         Null value will return with no write occurring.
 * @buf:   Trace debuging data to write to the PTI HW.
 *         Null value will return with no write occurring.
 * @count: Size of buf. Value of 0 or a negative number will
 *         return with no write occuring.
 */
void pti_writedata(struct pti_masterchannel *mc, u8 *buf, int count)
{
        /*
         * since this function is exported, this is treated like an
         * API function, thus, all parameters should
         * be checked for validity.
         */
        if ((mc != NULL) && (buf != NULL) && (count > 0))
                pti_write_to_aperture(mc, buf, count);
        return;
}
EXPORT_SYMBOL_GPL(pti_writedata);

/*
 * for the tty_driver_*() basic function descriptions, see tty_driver.h.
 * Specific header comments made for PTI-related specifics.
 */

/**
 * pti_tty_driver_open()- Open an Application master, channel aperture
 * ID to the PTI device via tty device.
 *
 * @tty: tty interface.
 * @filp: filp interface pased to tty_port_open() call.
 *
 * Returns:
 *      int, 0 for success
 *      otherwise, fail value
 *
 * The main purpose of using the tty device interface is for
 * each tty port to have a unique PTI write aperture.  In an
 * example use case, ttyPTI0 gets syslogd and an APP aperture
 * ID and ttyPTI1 is where the n_tracesink ldisc hooks to route
 * modem messages into PTI.  Modem trace data does not have to
 * go to ttyPTI1, but ttyPTI0 and ttyPTI1 do need to be distinct
 * master IDs.  These messages go through the PTI HW and out of
 * the handheld platform and to the Fido/Lauterbach device.
 */
static int pti_tty_driver_open(struct tty_struct *tty, struct file *filp)
{
        /*
         * we actually want to allocate a new channel per open, per
         * system arch.  HW gives more than plenty channels for a single
         * system task to have its own channel to write trace data. This
         * also removes a locking requirement for the actual write
         * procedure.
         */
        return tty_port_open(tty->port, tty, filp);
}

/**
 * pti_tty_driver_close()- close tty device and release Application
 * master, channel aperture ID to the PTI device via tty device.
 *
 * @tty: tty interface.
 * @filp: filp interface pased to tty_port_close() call.
 *
 * The main purpose of using the tty device interface is to route
 * syslog daemon messages to the PTI HW and out of the handheld platform
 * and to the Fido/Lauterbach device.
 */
static void pti_tty_driver_close(struct tty_struct *tty, struct file *filp)
{
        tty_port_close(tty->port, tty, filp);
}

/**
 * pti_tty_install()- Used to set up specific master-channels
 *                    to tty ports for organizational purposes when
 *                    tracing viewed from debuging tools.
 *
 * @driver: tty driver information.
 * @tty: tty struct containing pti information.
 *
 * Returns:
 *      0 for success
 *      otherwise, error
 */
static int pti_tty_install(struct tty_driver *driver, struct tty_struct *tty)
{
        int idx = tty->index;
        struct pti_tty *pti_tty_data;
        int ret = tty_standard_install(driver, tty);

        if (ret == 0) {
                pti_tty_data = kmalloc(sizeof(struct pti_tty), GFP_KERNEL);
                if (pti_tty_data == NULL)
                        return -ENOMEM;

                if (idx == PTITTY_MINOR_START)
                        pti_tty_data->mc = pti_request_masterchannel(0, NULL);
                else
                        pti_tty_data->mc = pti_request_masterchannel(2, NULL);

                if (pti_tty_data->mc == NULL) {
                        kfree(pti_tty_data);
                        return -ENXIO;
                }
                tty->driver_data = pti_tty_data;
        }

        return ret;
}

/**
 * pti_tty_cleanup()- Used to de-allocate master-channel resources
 *                    tied to tty's of this driver.
 *
 * @tty: tty struct containing pti information.
 */
static void pti_tty_cleanup(struct tty_struct *tty)
{
        struct pti_tty *pti_tty_data = tty->driver_data;
        if (pti_tty_data == NULL)
                return;
        pti_release_masterchannel(pti_tty_data->mc);
        kfree(pti_tty_data);
        tty->driver_data = NULL;
}

/**
 * pti_tty_driver_write()-  Write trace debugging data through the char
 * interface to the PTI HW.  Part of the misc device implementation.
 *
 * @filp: Contains private data which is used to obtain
 *        master, channel write ID.
 * @data: trace data to be written.
 * @len:  # of byte to write.
 *
 * Returns:
 *      int, # of bytes written
 *      otherwise, error
 */
static int pti_tty_driver_write(struct tty_struct *tty,
        const unsigned char *buf, int len)
{
        struct pti_tty *pti_tty_data = tty->driver_data;
        if ((pti_tty_data != NULL) && (pti_tty_data->mc != NULL)) {
                pti_write_to_aperture(pti_tty_data->mc, (u8 *)buf, len);
                return len;
        }
        /*
         * we can't write to the pti hardware if the private driver_data
         * and the mc address is not there.
         */
        else
                return -EFAULT;
}

/**
 * pti_tty_write_room()- Always returns 2048.
 *
 * @tty: contains tty info of the pti driver.
 */
static int pti_tty_write_room(struct tty_struct *tty)
{
        return 2048;
}

/**
 * pti_char_open()- Open an Application master, channel aperture
 * ID to the PTI device. Part of the misc device implementation.
 *
 * @inode: not used.
 * @filp:  Output- will have a masterchannel struct set containing
 *                 the allocated application PTI aperture write address.
 *
 * Returns:
 *      int, 0 for success
 *      otherwise, a fail value
 */
static int pti_char_open(struct inode *inode, struct file *filp)
{
        struct pti_masterchannel *mc;

        /*
         * We really do want to fail immediately if
         * pti_request_masterchannel() fails,
         * before assigning the value to filp->private_data.
         * Slightly easier to debug if this driver needs debugging.
         */
        mc = pti_request_masterchannel(0, NULL);
        if (mc == NULL)
                return -ENOMEM;
        filp->private_data = mc;
        return 0;
}

/**
 * pti_char_release()-  Close a char channel to the PTI device. Part
 * of the misc device implementation.
 *
 * @inode: Not used in this implementaiton.
 * @filp:  Contains private_data that contains the master, channel
 *         ID to be released by the PTI device.
 *
 * Returns:
 *      always 0
 */
static int pti_char_release(struct inode *inode, struct file *filp)
{
        pti_release_masterchannel(filp->private_data);
        filp->private_data = NULL;
        return 0;
}

/**
 * pti_char_write()-  Write trace debugging data through the char
 * interface to the PTI HW.  Part of the misc device implementation.
 *
 * @filp:  Contains private data which is used to obtain
 *         master, channel write ID.
 * @data:  trace data to be written.
 * @len:   # of byte to write.
 * @ppose: Not used in this function implementation.
 *
 * Returns:
 *      int, # of bytes written
 *      otherwise, error value
 *
 * Notes: From side discussions with Alan Cox and experimenting
 * with PTI debug HW like Nokia's Fido box and Lauterbach
 * devices, 8192 byte write buffer used by USER_COPY_SIZE was
 * deemed an appropriate size for this type of usage with
 * debugging HW.
 */
static ssize_t pti_char_write(struct file *filp, const char __user *data,
                              size_t len, loff_t *ppose)
{
        struct pti_masterchannel *mc;
        void *kbuf;
        const char __user *tmp;
        size_t size = USER_COPY_SIZE;
        size_t n = 0;

        tmp = data;
        mc = filp->private_data;

        kbuf = kmalloc(size, GFP_KERNEL);
        if (kbuf == NULL)  {
                pr_err("%s(%d): buf allocation failed\n",
                        __func__, __LINE__);
                return -ENOMEM;
        }

        do {
                if (len - n > USER_COPY_SIZE)
                        size = USER_COPY_SIZE;
                else
                        size = len - n;

                if (copy_from_user(kbuf, tmp, size)) {
                        kfree(kbuf);
                        return n ? n : -EFAULT;
                }

                pti_write_to_aperture(mc, kbuf, size);
                n  += size;
                tmp += size;

        } while (len > n);

        kfree(kbuf);
        return len;
}

static const struct tty_operations pti_tty_driver_ops = {
        .open           = pti_tty_driver_open,
        .close          = pti_tty_driver_close,
        .write          = pti_tty_driver_write,
        .write_room     = pti_tty_write_room,
        .install        = pti_tty_install,
        .cleanup        = pti_tty_cleanup
};

static const struct file_operations pti_char_driver_ops = {
        .owner          = THIS_MODULE,
        .write          = pti_char_write,
        .open           = pti_char_open,
        .release        = pti_char_release,
};

static struct miscdevice pti_char_driver = {
        .minor          = MISC_DYNAMIC_MINOR,
        .name           = CHARNAME,
        .fops           = &pti_char_driver_ops
};

/**
 * pti_console_write()-  Write to the console that has been acquired.
 *
 * @c:   Not used in this implementaiton.
 * @buf: Data to be written.
 * @len: Length of buf.
 */
static void pti_console_write(struct console *c, const char *buf, unsigned len)
{
        static struct pti_masterchannel mc = {.master  = CONSOLE_ID,
                                              .channel = 0};

        mc.channel = pti_console_channel;
        pti_console_channel = (pti_console_channel + 1) & 0x7f;

        pti_write_full_frame_to_aperture(&mc, buf, len);
}

/**
 * pti_console_device()-  Return the driver tty structure and set the
 *                        associated index implementation.
 *
 * @c:     Console device of the driver.
 * @index: index associated with c.
 *
 * Returns:
 *      always value of pti_tty_driver structure when this function
 *      is called.
 */
static struct tty_driver *pti_console_device(struct console *c, int *index)
{
        *index = c->index;
        return pti_tty_driver;
}

/**
 * pti_console_setup()-  Initialize console variables used by the driver.
 *
 * @c:     Not used.
 * @opts:  Not used.
 *
 * Returns:
 *      always 0.
 */
static int pti_console_setup(struct console *c, char *opts)
{
        pti_console_channel = 0;
        pti_control_channel = 0;
        return 0;
}

/*
 * pti_console struct, used to capture OS printk()'s and shift
 * out to the PTI device for debugging.  This cannot be
 * enabled upon boot because of the possibility of eating
 * any serial console printk's (race condition discovered).
 * The console should be enabled upon when the tty port is
 * used for the first time.  Since the primary purpose for
 * the tty port is to hook up syslog to it, the tty port
 * will be open for a really long time.
 */
static struct console pti_console = {
        .name           = TTYNAME,
        .write          = pti_console_write,
        .device         = pti_console_device,
        .setup          = pti_console_setup,
        .flags          = CON_PRINTBUFFER,
        .index          = 0,
};

/**
 * pti_port_activate()- Used to start/initialize any items upon
 * first opening of tty_port().
 *
 * @port- The tty port number of the PTI device.
 * @tty-  The tty struct associated with this device.
 *
 * Returns:
 *      always returns 0
 *
 * Notes: The primary purpose of the PTI tty port 0 is to hook
 * the syslog daemon to it; thus this port will be open for a
 * very long time.
 */
static int pti_port_activate(struct tty_port *port, struct tty_struct *tty)
{
        if (port->tty->index == PTITTY_MINOR_START)
                console_start(&pti_console);
        return 0;
}

/**
 * pti_port_shutdown()- Used to stop/shutdown any items upon the
 * last tty port close.
 *
 * @port- The tty port number of the PTI device.
 *
 * Notes: The primary purpose of the PTI tty port 0 is to hook
 * the syslog daemon to it; thus this port will be open for a
 * very long time.
 */
static void pti_port_shutdown(struct tty_port *port)
{
        if (port->tty->index == PTITTY_MINOR_START)
                console_stop(&pti_console);
}

static const struct tty_port_operations tty_port_ops = {
        .activate = pti_port_activate,
        .shutdown = pti_port_shutdown,
};

/*
 * Note the _probe() call sets everything up and ties the char and tty
 * to successfully detecting the PTI device on the pci bus.
 */

/**
 * pti_pci_probe()- Used to detect pti on the pci bus and set
 *                  things up in the driver.
 *
 * @pdev- pci_dev struct values for pti.
 * @ent-  pci_device_id struct for pti driver.
 *
 * Returns:
 *      0 for success
 *      otherwise, error
 */
static int pti_pci_probe(struct pci_dev *pdev,
                const struct pci_device_id *ent)
{
        unsigned int a;
        int retval;
        int pci_bar = 1;

        dev_dbg(&pdev->dev, "%s %s(%d): PTI PCI ID %04x:%04x\n", __FILE__,
                        __func__, __LINE__, pdev->vendor, pdev->device);

        retval = misc_register(&pti_char_driver);
        if (retval) {
                pr_err("%s(%d): CHAR registration failed of pti driver\n",
                        __func__, __LINE__);
                pr_err("%s(%d): Error value returned: %d\n",
                        __func__, __LINE__, retval);
                goto err;
        }

        retval = pci_enable_device(pdev);
        if (retval != 0) {
                dev_err(&pdev->dev,
                        "%s: pci_enable_device() returned error %d\n",
                        __func__, retval);
                goto err_unreg_misc;
        }

        drv_data = kzalloc(sizeof(*drv_data), GFP_KERNEL);
        if (drv_data == NULL) {
                retval = -ENOMEM;
                dev_err(&pdev->dev,
                        "%s(%d): kmalloc() returned NULL memory.\n",
                        __func__, __LINE__);
                goto err_disable_pci;
        }
        drv_data->pti_addr = pci_resource_start(pdev, pci_bar);

        retval = pci_request_region(pdev, pci_bar, dev_name(&pdev->dev));
        if (retval != 0) {
                dev_err(&pdev->dev,
                        "%s(%d): pci_request_region() returned error %d\n",
                        __func__, __LINE__, retval);
                goto err_free_dd;
        }
        drv_data->aperture_base = drv_data->pti_addr+APERTURE_14;
        drv_data->pti_ioaddr =
                ioremap((u32)drv_data->aperture_base,
                APERTURE_LEN);
        if (!drv_data->pti_ioaddr) {
                retval = -ENOMEM;
                goto err_rel_reg;
        }

        pci_set_drvdata(pdev, drv_data);

        for (a = 0; a < PTITTY_MINOR_NUM; a++) {
                struct tty_port *port = &drv_data->port[a];
                tty_port_init(port);
                port->ops = &tty_port_ops;

                tty_port_register_device(port, pti_tty_driver, a, &pdev->dev);
        }

        register_console(&pti_console);

        return 0;
err_rel_reg:
        pci_release_region(pdev, pci_bar);
err_free_dd:
        kfree(drv_data);
err_disable_pci:
        pci_disable_device(pdev);
err_unreg_misc:
        misc_deregister(&pti_char_driver);
err:
        return retval;
}

/**
 * pti_pci_remove()- Driver exit method to remove PTI from
 *                 PCI bus.
 * @pdev: variable containing pci info of PTI.
 */
static void pti_pci_remove(struct pci_dev *pdev)
{
        struct pti_dev *drv_data = pci_get_drvdata(pdev);
        unsigned int a;

        unregister_console(&pti_console);

        for (a = 0; a < PTITTY_MINOR_NUM; a++) {
                tty_unregister_device(pti_tty_driver, a);
                tty_port_destroy(&drv_data->port[a]);
        }

        iounmap(drv_data->pti_ioaddr);
        kfree(drv_data);
        pci_release_region(pdev, 1);
        pci_disable_device(pdev);

        misc_deregister(&pti_char_driver);
}

static struct pci_driver pti_pci_driver = {
        .name           = PCINAME,
        .id_table       = pci_ids,
        .probe          = pti_pci_probe,
        .remove         = pti_pci_remove,
};

/**
 *
 * pti_init()- Overall entry/init call to the pti driver.
 *             It starts the registration process with the kernel.
 *
 * Returns:
 *      int __init, 0 for success
 *      otherwise value is an error
 *
 */
static int __init pti_init(void)
{
        int retval;

        /* First register module as tty device */

        pti_tty_driver = alloc_tty_driver(PTITTY_MINOR_NUM);
        if (pti_tty_driver == NULL) {
                pr_err("%s(%d): Memory allocation failed for ptiTTY driver\n",
                        __func__, __LINE__);
                return -ENOMEM;
        }

        pti_tty_driver->driver_name             = DRIVERNAME;
        pti_tty_driver->name                    = TTYNAME;
        pti_tty_driver->major                   = 0;
        pti_tty_driver->minor_start             = PTITTY_MINOR_START;
        pti_tty_driver->type                    = TTY_DRIVER_TYPE_SYSTEM;
        pti_tty_driver->subtype                 = SYSTEM_TYPE_SYSCONS;
        pti_tty_driver->flags                   = TTY_DRIVER_REAL_RAW |
                                                  TTY_DRIVER_DYNAMIC_DEV;
        pti_tty_driver->init_termios            = tty_std_termios;

        tty_set_operations(pti_tty_driver, &pti_tty_driver_ops);

        retval = tty_register_driver(pti_tty_driver);
        if (retval) {
                pr_err("%s(%d): TTY registration failed of pti driver\n",
                        __func__, __LINE__);
                pr_err("%s(%d): Error value returned: %d\n",
                        __func__, __LINE__, retval);

                goto put_tty;
        }

        retval = pci_register_driver(&pti_pci_driver);
        if (retval) {
                pr_err("%s(%d): PCI registration failed of pti driver\n",
                        __func__, __LINE__);
                pr_err("%s(%d): Error value returned: %d\n",
                        __func__, __LINE__, retval);
                goto unreg_tty;
        }

        return 0;
unreg_tty:
        tty_unregister_driver(pti_tty_driver);
put_tty:
        put_tty_driver(pti_tty_driver);
        pti_tty_driver = NULL;
        return retval;
}

/**
 * pti_exit()- Unregisters this module as a tty and pci driver.
 */
static void __exit pti_exit(void)
{
        tty_unregister_driver(pti_tty_driver);
        pci_unregister_driver(&pti_pci_driver);
        put_tty_driver(pti_tty_driver);
}

module_init(pti_init);
module_exit(pti_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Ken Mills, Jay Freyensee");
MODULE_DESCRIPTION("PTI Driver");