USB: usbserial: mos7720: add support for parallel port on moschip 7715
[pandora-kernel.git] / drivers / usb / serial / mos7720.c
index 0d47f2c..2d35d11 100644 (file)
 #include <linux/usb.h>
 #include <linux/usb/serial.h>
 #include <linux/uaccess.h>
-
+#include <linux/parport.h>
 
 /*
  * Version Information
  */
-#define DRIVER_VERSION "1.0.0.4F"
+#define DRIVER_VERSION "2.0"
 #define DRIVER_AUTHOR "Aspire Communications pvt Ltd."
 #define DRIVER_DESC "Moschip USB Serial Driver"
 
@@ -63,7 +63,7 @@
 #define NUM_URBS                       16      /* URB Count */
 #define URB_TRANSFER_BUFFER_SIZE       32      /* URB Size */
 
-/* This structure holds all of the local port information */
+/* This structure holds all of the local serial port information */
 struct moschip_port {
        __u8    shadowLCR;              /* last LCR value received */
        __u8    shadowMCR;              /* last MCR value received */
@@ -74,11 +74,6 @@ struct moschip_port {
        struct urb              *write_urb_pool[NUM_URBS];
 };
 
-/* This structure holds all of the individual serial device information */
-struct moschip_serial {
-       int interrupt_started;
-};
-
 static int debug;
 
 static struct usb_serial_driver moschip7720_2port_driver;
@@ -94,6 +89,649 @@ static const struct usb_device_id moschip_port_id_table[] = {
 };
 MODULE_DEVICE_TABLE(usb, moschip_port_id_table);
 
+#ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
+
+/* initial values for parport regs */
+#define DCR_INIT_VAL       0x0c        /* SLCTIN, nINIT */
+#define ECR_INIT_VAL       0x00        /* SPP mode */
+
+struct urbtracker {
+       struct mos7715_parport  *mos_parport;
+       struct list_head        urblist_entry;
+       struct kref             ref_count;
+       struct urb              *urb;
+};
+
+enum mos7715_pp_modes {
+       SPP = 0<<5,
+       PS2 = 1<<5,      /* moschip calls this 'NIBBLE' mode */
+       PPF = 2<<5,      /* moschip calls this 'CB-FIFO mode */
+};
+
+struct mos7715_parport {
+       struct parport          *pp;           /* back to containing struct */
+       struct kref             ref_count;     /* to instance of this struct */
+       struct list_head        deferred_urbs; /* list deferred async urbs */
+       struct list_head        active_urbs;   /* list async urbs in flight */
+       spinlock_t              listlock;      /* protects list access */
+       bool                    msg_pending;   /* usb sync call pending */
+       struct completion       syncmsg_compl; /* usb sync call completed */
+       struct tasklet_struct   urb_tasklet;   /* for sending deferred urbs */
+       struct usb_serial       *serial;       /* back to containing struct */
+       __u8                    shadowECR;     /* parallel port regs... */
+       __u8                    shadowDCR;
+       atomic_t                shadowDSR;     /* updated in int-in callback */
+};
+
+/* lock guards against dereferencing NULL ptr in parport ops callbacks */
+static DEFINE_SPINLOCK(release_lock);
+
+enum mos_regs {
+       THR,              /* serial port regs */
+       RHR,
+       IER,
+       FCR,
+       ISR,
+       LCR,
+       MCR,
+       LSR,
+       MSR,
+       SPR,
+       DLL,
+       DLM,
+       DPR,              /* parallel port regs */
+       DSR,
+       DCR,
+       ECR,
+       SP1_REG,          /* device control regs */
+       SP2_REG,          /* serial port 2 (7720 only) */
+       PP_REG,
+       SP_CONTROL_REG,
+};
+
+/*
+ * Return the correct value for the Windex field of the setup packet
+ * for a control endpoint message.  See the 7715 datasheet.
+ */
+static inline __u16 get_reg_index(enum mos_regs reg)
+{
+       static const __u16 mos7715_index_lookup_table[] = {
+               0x00,           /* THR */
+               0x00,           /* RHR */
+               0x01,           /* IER */
+               0x02,           /* FCR */
+               0x02,           /* ISR */
+               0x03,           /* LCR */
+               0x04,           /* MCR */
+               0x05,           /* LSR */
+               0x06,           /* MSR */
+               0x07,           /* SPR */
+               0x00,           /* DLL */
+               0x01,           /* DLM */
+               0x00,           /* DPR */
+               0x01,           /* DSR */
+               0x02,           /* DCR */
+               0x0a,           /* ECR */
+               0x01,           /* SP1_REG */
+               0x02,           /* SP2_REG (7720 only) */
+               0x04,           /* PP_REG (7715 only) */
+               0x08,           /* SP_CONTROL_REG */
+       };
+       return mos7715_index_lookup_table[reg];
+}
+
+/*
+ * Return the correct value for the upper byte of the Wvalue field of
+ * the setup packet for a control endpoint message.
+ */
+static inline __u16 get_reg_value(enum mos_regs reg)
+{
+       if (reg >= SP1_REG)           /* control reg */
+               return 0x0000;
+       else                          /* parallel port reg (7715 only) */
+               return 0x0100;
+}
+
+/*
+ * Write data byte to the specified device register.  The data is embedded in
+ * the value field of the setup packet.
+ */
+static int write_parport_reg(struct mos7715_parport *mos_parport,
+                            enum mos_regs reg, __u8 data)
+{
+       struct usb_serial *serial = mos_parport->serial;
+       struct usb_device *usbdev = serial->dev;
+       unsigned int pipe = usb_sndctrlpipe(usbdev, 0);
+       __u8 request = (__u8)0x0e;
+       __u8 requesttype = (__u8)0x40;
+       __u16 value = get_reg_value(reg) + data;
+       __u16 index = get_reg_index(reg);
+       __u16 size = 0;
+       int status;
+       status = usb_control_msg(usbdev, pipe, request, requesttype, value,
+                                index, NULL, size, MOS_WDR_TIMEOUT);
+       if (status < 0)
+               dev_err(&usbdev->dev,
+                       "mos7720: usb_control_msg() failed: %d", status);
+       return status;
+}
+
+/*
+ * Read data byte from the specified device register.  The data returned by the
+ * device is embedded in the value field of the setup packet.
+ */
+static int read_parport_reg(struct mos7715_parport *mos_parport,
+                           enum mos_regs reg, __u8 *data)
+{
+       struct usb_device *usbdev = mos_parport->serial->dev;
+       unsigned int pipe = usb_rcvctrlpipe(usbdev, 0);
+       __u8 request = (__u8)0x0d;
+       __u8 requesttype = (__u8)0xc0;
+       __u16 value = get_reg_value(reg);
+       __u16 index = get_reg_index(reg);
+       __u16 size = 1;
+       int status = usb_control_msg(usbdev, pipe, request, requesttype, value,
+                                    index, data, size, MOS_WDR_TIMEOUT);
+       if (status < 0)
+               dev_err(&usbdev->dev,
+                       "mos7720: usb_control_msg() failed: %d", status);
+       return status;
+}
+
+static inline int mos7715_change_mode(struct mos7715_parport *mos_parport,
+                                     enum mos7715_pp_modes mode)
+{
+       mos_parport->shadowECR = mode;
+       write_parport_reg(mos_parport, ECR, mos_parport->shadowECR);
+       return 0;
+}
+
+static void destroy_mos_parport(struct kref *kref)
+{
+       struct mos7715_parport *mos_parport =
+               container_of(kref, struct mos7715_parport, ref_count);
+
+       dbg("%s called", __func__);
+       kfree(mos_parport);
+}
+
+static void destroy_urbtracker(struct kref *kref)
+{
+       struct urbtracker *urbtrack =
+               container_of(kref, struct urbtracker, ref_count);
+       struct mos7715_parport *mos_parport = urbtrack->mos_parport;
+       dbg("%s called", __func__);
+       usb_free_urb(urbtrack->urb);
+       kfree(urbtrack);
+       kref_put(&mos_parport->ref_count, destroy_mos_parport);
+}
+
+/*
+ * This runs as a tasklet when sending an urb in a non-blocking parallel
+ * port callback had to be deferred because the disconnect mutex could not be
+ * obtained at the time.
+ */
+static void send_deferred_urbs(unsigned long _mos_parport)
+{
+       int ret_val;
+       unsigned long flags;
+       struct mos7715_parport *mos_parport = (void *)_mos_parport;
+       struct urbtracker *urbtrack;
+       struct list_head *cursor, *next;
+
+       dbg("%s called", __func__);
+
+       /* if release function ran, game over */
+       if (unlikely(mos_parport->serial == NULL))
+               return;
+
+       /* try again to get the mutex */
+       if (!mutex_trylock(&mos_parport->serial->disc_mutex)) {
+               dbg("%s: rescheduling tasklet", __func__);
+               tasklet_schedule(&mos_parport->urb_tasklet);
+               return;
+       }
+
+       /* if device disconnected, game over */
+       if (unlikely(mos_parport->serial->disconnected)) {
+               mutex_unlock(&mos_parport->serial->disc_mutex);
+               return;
+       }
+
+       spin_lock_irqsave(&mos_parport->listlock, flags);
+       if (list_empty(&mos_parport->deferred_urbs)) {
+               spin_unlock_irqrestore(&mos_parport->listlock, flags);
+               mutex_unlock(&mos_parport->serial->disc_mutex);
+               dbg("%s: deferred_urbs list empty", __func__);
+               return;
+       }
+
+       /* move contents of deferred_urbs list to active_urbs list and submit */
+       list_for_each_safe(cursor, next, &mos_parport->deferred_urbs)
+               list_move_tail(cursor, &mos_parport->active_urbs);
+       list_for_each_entry(urbtrack, &mos_parport->active_urbs,
+                           urblist_entry) {
+               ret_val = usb_submit_urb(urbtrack->urb, GFP_ATOMIC);
+               dbg("%s: urb submitted", __func__);
+               if (ret_val) {
+                       dev_err(&mos_parport->serial->dev->dev,
+                               "usb_submit_urb() failed: %d", ret_val);
+                       list_del(&urbtrack->urblist_entry);
+                       kref_put(&urbtrack->ref_count, destroy_urbtracker);
+               }
+       }
+       spin_unlock_irqrestore(&mos_parport->listlock, flags);
+       mutex_unlock(&mos_parport->serial->disc_mutex);
+}
+
+/* callback for parallel port control urbs submitted asynchronously */
+static void async_complete(struct urb *urb)
+{
+       struct urbtracker *urbtrack = urb->context;
+       int status = urb->status;
+       dbg("%s called", __func__);
+       if (unlikely(status))
+               dbg("%s - nonzero urb status received: %d", __func__, status);
+
+       /* remove the urbtracker from the active_urbs list */
+       spin_lock(&urbtrack->mos_parport->listlock);
+       list_del(&urbtrack->urblist_entry);
+       spin_unlock(&urbtrack->mos_parport->listlock);
+       kref_put(&urbtrack->ref_count, destroy_urbtracker);
+}
+
+static int write_parport_reg_nonblock(struct mos7715_parport *mos_parport,
+                                     enum mos_regs reg, __u8 data)
+{
+       struct urbtracker *urbtrack;
+       int ret_val;
+       unsigned long flags;
+       struct usb_ctrlrequest setup;
+       struct usb_serial *serial = mos_parport->serial;
+       struct usb_device *usbdev = serial->dev;
+       dbg("%s called", __func__);
+
+       /* create and initialize the control urb and containing urbtracker */
+       urbtrack = kmalloc(sizeof(struct urbtracker), GFP_ATOMIC);
+       if (urbtrack == NULL) {
+               dev_err(&usbdev->dev, "out of memory");
+               return -ENOMEM;
+       }
+       kref_get(&mos_parport->ref_count);
+       urbtrack->mos_parport = mos_parport;
+       urbtrack->urb = usb_alloc_urb(0, GFP_ATOMIC);
+       if (urbtrack->urb == NULL) {
+               dev_err(&usbdev->dev, "out of urbs");
+               kfree(urbtrack);
+               return -ENOMEM;
+       }
+       setup.bRequestType = (__u8)0x40;
+       setup.bRequest = (__u8)0x0e;
+       setup.wValue = get_reg_value(reg);
+       setup.wIndex = get_reg_index(reg);
+       setup.wLength = 0;
+       usb_fill_control_urb(urbtrack->urb, usbdev,
+                            usb_sndctrlpipe(usbdev, 0),
+                            (unsigned char *)&setup,
+                            NULL, 0, async_complete, urbtrack);
+       kref_init(&urbtrack->ref_count);
+       INIT_LIST_HEAD(&urbtrack->urblist_entry);
+
+       /*
+        * get the disconnect mutex, or add tracker to the deferred_urbs list
+        * and schedule a tasklet to try again later
+        */
+       if (!mutex_trylock(&serial->disc_mutex)) {
+               spin_lock_irqsave(&mos_parport->listlock, flags);
+               list_add_tail(&urbtrack->urblist_entry,
+                             &mos_parport->deferred_urbs);
+               spin_unlock_irqrestore(&mos_parport->listlock, flags);
+               tasklet_schedule(&mos_parport->urb_tasklet);
+               dbg("tasklet scheduled");
+               return 0;
+       }
+
+       /* bail if device disconnected */
+       if (serial->disconnected) {
+               kref_put(&urbtrack->ref_count, destroy_urbtracker);
+               mutex_unlock(&serial->disc_mutex);
+               return -ENODEV;
+       }
+
+       /* add the tracker to the active_urbs list and submit */
+       spin_lock_irqsave(&mos_parport->listlock, flags);
+       list_add_tail(&urbtrack->urblist_entry, &mos_parport->active_urbs);
+       spin_unlock_irqrestore(&mos_parport->listlock, flags);
+       ret_val = usb_submit_urb(urbtrack->urb, GFP_ATOMIC);
+       mutex_unlock(&serial->disc_mutex);
+       if (ret_val) {
+               dev_err(&usbdev->dev,
+                       "%s: submit_urb() failed: %d", __func__, ret_val);
+               spin_lock_irqsave(&mos_parport->listlock, flags);
+               list_del(&urbtrack->urblist_entry);
+               spin_unlock_irqrestore(&mos_parport->listlock, flags);
+               kref_put(&urbtrack->ref_count, destroy_urbtracker);
+               return ret_val;
+       }
+       return 0;
+}
+
+/*
+ * This is the the common top part of all parallel port callback operations that
+ * send synchronous messages to the device.  This implements convoluted locking
+ * that avoids two scenarios: (1) a port operation is called after usbserial
+ * has called our release function, at which point struct mos7715_parport has
+ * been destroyed, and (2) the device has been disconnected, but usbserial has
+ * not called the release function yet because someone has a serial port open.
+ * The shared release_lock prevents the first, and the mutex and disconnected
+ * flag maintained by usbserial covers the second.  We also use the msg_pending
+ * flag to ensure that all synchronous usb messgage calls have completed before
+ * our release function can return.
+ */
+static int parport_prologue(struct parport *pp)
+{
+       struct mos7715_parport *mos_parport;
+
+       spin_lock(&release_lock);
+       mos_parport = pp->private_data;
+       if (unlikely(mos_parport == NULL)) {
+               /* release fn called, port struct destroyed */
+               spin_unlock(&release_lock);
+               return -1;
+       }
+       mos_parport->msg_pending = true;   /* synch usb call pending */
+       INIT_COMPLETION(mos_parport->syncmsg_compl);
+       spin_unlock(&release_lock);
+
+       mutex_lock(&mos_parport->serial->disc_mutex);
+       if (mos_parport->serial->disconnected) {
+               /* device disconnected */
+               mutex_unlock(&mos_parport->serial->disc_mutex);
+               mos_parport->msg_pending = false;
+               complete(&mos_parport->syncmsg_compl);
+               return -1;
+       }
+
+       return 0;
+}
+
+/*
+ * This is the the common bottom part of all parallel port functions that send
+ * synchronous messages to the device.
+ */
+static inline void parport_epilogue(struct parport *pp)
+{
+       struct mos7715_parport *mos_parport = pp->private_data;
+       mutex_unlock(&mos_parport->serial->disc_mutex);
+       mos_parport->msg_pending = false;
+       complete(&mos_parport->syncmsg_compl);
+}
+
+static void parport_mos7715_write_data(struct parport *pp, unsigned char d)
+{
+       struct mos7715_parport *mos_parport = pp->private_data;
+       dbg("%s called: %2.2x", __func__, d);
+       if (parport_prologue(pp) < 0)
+               return;
+       mos7715_change_mode(mos_parport, SPP);
+       write_parport_reg(mos_parport, DPR, (__u8)d);
+       parport_epilogue(pp);
+}
+
+static unsigned char parport_mos7715_read_data(struct parport *pp)
+{
+       struct mos7715_parport *mos_parport = pp->private_data;
+       unsigned char d;
+       dbg("%s called", __func__);
+       if (parport_prologue(pp) < 0)
+               return 0;
+       read_parport_reg(mos_parport, DPR, &d);
+       parport_epilogue(pp);
+       return d;
+}
+
+static void parport_mos7715_write_control(struct parport *pp, unsigned char d)
+{
+       struct mos7715_parport *mos_parport = pp->private_data;
+       __u8 data;
+       dbg("%s called: %2.2x", __func__, d);
+       if (parport_prologue(pp) < 0)
+               return;
+       data = ((__u8)d & 0x0f) | (mos_parport->shadowDCR & 0xf0);
+       write_parport_reg(mos_parport, DCR, data);
+       mos_parport->shadowDCR = data;
+       parport_epilogue(pp);
+}
+
+static unsigned char parport_mos7715_read_control(struct parport *pp)
+{
+       struct mos7715_parport *mos_parport = pp->private_data;
+       __u8 dcr;
+       dbg("%s called", __func__);
+       spin_lock(&release_lock);
+       mos_parport = pp->private_data;
+       if (unlikely(mos_parport == NULL)) {
+               spin_unlock(&release_lock);
+               return 0;
+       }
+       dcr = mos_parport->shadowDCR & 0x0f;
+       spin_unlock(&release_lock);
+       return dcr;
+}
+
+static unsigned char parport_mos7715_frob_control(struct parport *pp,
+                                                 unsigned char mask,
+                                                 unsigned char val)
+{
+       struct mos7715_parport *mos_parport = pp->private_data;
+       __u8 dcr;
+       dbg("%s called", __func__);
+       mask &= 0x0f;
+       val &= 0x0f;
+       if (parport_prologue(pp) < 0)
+               return 0;
+       mos_parport->shadowDCR = (mos_parport->shadowDCR & (~mask)) ^ val;
+       write_parport_reg(mos_parport, DCR, mos_parport->shadowDCR);
+       dcr = mos_parport->shadowDCR & 0x0f;
+       parport_epilogue(pp);
+       return dcr;
+}
+
+static unsigned char parport_mos7715_read_status(struct parport *pp)
+{
+       unsigned char status;
+       struct mos7715_parport *mos_parport = pp->private_data;
+       dbg("%s called", __func__);
+       spin_lock(&release_lock);
+       mos_parport = pp->private_data;
+       if (unlikely(mos_parport == NULL)) {    /* release called */
+               spin_unlock(&release_lock);
+               return 0;
+       }
+       status = atomic_read(&mos_parport->shadowDSR) & 0xf8;
+       spin_unlock(&release_lock);
+       return status;
+}
+
+static void parport_mos7715_enable_irq(struct parport *pp)
+{
+       dbg("%s called", __func__);
+}
+static void parport_mos7715_disable_irq(struct parport *pp)
+{
+       dbg("%s called", __func__);
+}
+
+static void parport_mos7715_data_forward(struct parport *pp)
+{
+       struct mos7715_parport *mos_parport = pp->private_data;
+       dbg("%s called", __func__);
+       if (parport_prologue(pp) < 0)
+               return;
+       mos7715_change_mode(mos_parport, PS2);
+       mos_parport->shadowDCR &=  ~0x20;
+       write_parport_reg(mos_parport, DCR, mos_parport->shadowDCR);
+       parport_epilogue(pp);
+}
+
+static void parport_mos7715_data_reverse(struct parport *pp)
+{
+       struct mos7715_parport *mos_parport = pp->private_data;
+       dbg("%s called", __func__);
+       if (parport_prologue(pp) < 0)
+               return;
+       mos7715_change_mode(mos_parport, PS2);
+       mos_parport->shadowDCR |= 0x20;
+       write_parport_reg(mos_parport, DCR, mos_parport->shadowDCR);
+       parport_epilogue(pp);
+}
+
+static void parport_mos7715_init_state(struct pardevice *dev,
+                                      struct parport_state *s)
+{
+       dbg("%s called", __func__);
+       s->u.pc.ctr = DCR_INIT_VAL;
+       s->u.pc.ecr = ECR_INIT_VAL;
+}
+
+/* N.B. Parport core code requires that this function not block */
+static void parport_mos7715_save_state(struct parport *pp,
+                                      struct parport_state *s)
+{
+       struct mos7715_parport *mos_parport;
+       dbg("%s called", __func__);
+       spin_lock(&release_lock);
+       mos_parport = pp->private_data;
+       if (unlikely(mos_parport == NULL)) {    /* release called */
+               spin_unlock(&release_lock);
+               return;
+       }
+       s->u.pc.ctr = mos_parport->shadowDCR;
+       s->u.pc.ecr = mos_parport->shadowECR;
+       spin_unlock(&release_lock);
+}
+
+/* N.B. Parport core code requires that this function not block */
+static void parport_mos7715_restore_state(struct parport *pp,
+                                         struct parport_state *s)
+{
+       struct mos7715_parport *mos_parport;
+       dbg("%s called", __func__);
+       spin_lock(&release_lock);
+       mos_parport = pp->private_data;
+       if (unlikely(mos_parport == NULL)) {    /* release called */
+               spin_unlock(&release_lock);
+               return;
+       }
+       write_parport_reg_nonblock(mos_parport, DCR, mos_parport->shadowDCR);
+       write_parport_reg_nonblock(mos_parport, ECR, mos_parport->shadowECR);
+       spin_unlock(&release_lock);
+}
+
+static size_t parport_mos7715_write_compat(struct parport *pp,
+                                          const void *buffer,
+                                          size_t len, int flags)
+{
+       int retval;
+       struct mos7715_parport *mos_parport = pp->private_data;
+       int actual_len;
+       dbg("%s called: %u chars", __func__, (unsigned int)len);
+       if (parport_prologue(pp) < 0)
+               return 0;
+       mos7715_change_mode(mos_parport, PPF);
+       retval = usb_bulk_msg(mos_parport->serial->dev,
+                             usb_sndbulkpipe(mos_parport->serial->dev, 2),
+                             (void *)buffer, len, &actual_len,
+                             MOS_WDR_TIMEOUT);
+       parport_epilogue(pp);
+       if (retval) {
+               dev_err(&mos_parport->serial->dev->dev,
+                       "mos7720: usb_bulk_msg() failed: %d", retval);
+               return 0;
+       }
+       return actual_len;
+}
+
+static struct parport_operations parport_mos7715_ops = {
+       .owner =                THIS_MODULE,
+       .write_data =           parport_mos7715_write_data,
+       .read_data =            parport_mos7715_read_data,
+
+       .write_control =        parport_mos7715_write_control,
+       .read_control =         parport_mos7715_read_control,
+       .frob_control =         parport_mos7715_frob_control,
+
+       .read_status =          parport_mos7715_read_status,
+
+       .enable_irq =           parport_mos7715_enable_irq,
+       .disable_irq =          parport_mos7715_disable_irq,
+
+       .data_forward =         parport_mos7715_data_forward,
+       .data_reverse =         parport_mos7715_data_reverse,
+
+       .init_state =           parport_mos7715_init_state,
+       .save_state =           parport_mos7715_save_state,
+       .restore_state =        parport_mos7715_restore_state,
+
+       .compat_write_data =    parport_mos7715_write_compat,
+
+       .nibble_read_data =     parport_ieee1284_read_nibble,
+       .byte_read_data =       parport_ieee1284_read_byte,
+};
+
+/*
+ * Allocate and initialize parallel port control struct, initialize
+ * the parallel port hardware device, and register with the parport subsystem.
+ */
+static int mos7715_parport_init(struct usb_serial *serial)
+{
+       struct mos7715_parport *mos_parport;
+
+       /* allocate and initialize parallel port control struct */
+       mos_parport = kzalloc(sizeof(struct mos7715_parport), GFP_KERNEL);
+       if (mos_parport == NULL) {
+               dbg("mos7715_parport_init: kzalloc failed");
+               return -ENOMEM;
+       }
+       mos_parport->msg_pending = false;
+       kref_init(&mos_parport->ref_count);
+       spin_lock_init(&mos_parport->listlock);
+       INIT_LIST_HEAD(&mos_parport->active_urbs);
+       INIT_LIST_HEAD(&mos_parport->deferred_urbs);
+       usb_set_serial_data(serial, mos_parport); /* hijack private pointer */
+       mos_parport->serial = serial;
+       tasklet_init(&mos_parport->urb_tasklet, send_deferred_urbs,
+                    (unsigned long) mos_parport);
+       init_completion(&mos_parport->syncmsg_compl);
+
+       /* cycle parallel port reset bit */
+       write_parport_reg(mos_parport, PP_REG, (__u8)0x80);
+       write_parport_reg(mos_parport, PP_REG, (__u8)0x00);
+
+       /* initialize device registers */
+       mos_parport->shadowDCR = DCR_INIT_VAL;
+       write_parport_reg(mos_parport, DCR, mos_parport->shadowDCR);
+       mos_parport->shadowECR = ECR_INIT_VAL;
+       write_parport_reg(mos_parport, ECR, mos_parport->shadowECR);
+
+       /* register with parport core */
+       mos_parport->pp = parport_register_port(0, PARPORT_IRQ_NONE,
+                                               PARPORT_DMA_NONE,
+                                               &parport_mos7715_ops);
+       if (mos_parport->pp == NULL) {
+               dev_err(&serial->interface->dev,
+                       "Could not register parport\n");
+               kref_put(&mos_parport->ref_count, destroy_mos_parport);
+               return -EIO;
+       }
+       mos_parport->pp->private_data = mos_parport;
+       mos_parport->pp->modes = PARPORT_MODE_COMPAT | PARPORT_MODE_PCSPP;
+       mos_parport->pp->dev = &serial->interface->dev;
+       parport_announce_port(mos_parport->pp);
+
+       return 0;
+}
+#endif /* CONFIG_USB_SERIAL_MOS7715_PARPORT */
 
 /*
  * mos7720_interrupt_callback
@@ -109,8 +747,6 @@ static void mos7720_interrupt_callback(struct urb *urb)
        __u8 sp1;
        __u8 sp2;
 
-       dbg(" : Entering");
-
        switch (status) {
        case 0:
                /* success */
@@ -118,6 +754,7 @@ static void mos7720_interrupt_callback(struct urb *urb)
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
+       case -ENODEV:
                /* this urb is terminated, clean up */
                dbg("%s - urb shutting down with status: %d", __func__,
                    status);
@@ -161,7 +798,7 @@ static void mos7720_interrupt_callback(struct urb *urb)
                        dbg("Serial Port 1: Receiver time out");
                        break;
                case SERIAL_IIR_MS:
-                       dbg("Serial Port 1: Modem status change");
+                       /* dbg("Serial Port 1: Modem status change"); */
                        break;
                }
 
@@ -174,7 +811,7 @@ static void mos7720_interrupt_callback(struct urb *urb)
                        dbg("Serial Port 2: Receiver time out");
                        break;
                case SERIAL_IIR_MS:
-                       dbg("Serial Port 2: Modem status change");
+                       /* dbg("Serial Port 2: Modem status change"); */
                        break;
                }
        }
@@ -208,6 +845,7 @@ static void mos7715_interrupt_callback(struct urb *urb)
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
+       case -ENODEV:
                /* this urb is terminated, clean up */
                dbg("%s - urb shutting down with status: %d", __func__,
                    status);
@@ -243,11 +881,21 @@ static void mos7715_interrupt_callback(struct urb *urb)
                        dbg("Serial Port: Receiver time out");
                        break;
                case SERIAL_IIR_MS:
-                       dbg("Serial Port: Modem status change");
+                       /* dbg("Serial Port: Modem status change"); */
                        break;
                }
        }
 
+#ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
+       {       /* update local copy of DSR reg */
+               struct usb_serial_port *port = urb->context;
+               struct mos7715_parport *mos_parport = port->serial->private;
+               if (unlikely(mos_parport == NULL))
+                       return;
+               atomic_set(&mos_parport->shadowDSR, data[2]);
+       }
+#endif
+
 exit:
        result = usb_submit_urb(urb, GFP_ATOMIC);
        if (result)
@@ -267,7 +915,6 @@ static void mos7720_bulk_in_callback(struct urb *urb)
        int retval;
        unsigned char *data ;
        struct usb_serial_port *port;
-       struct moschip_port *mos7720_port;
        struct tty_struct *tty;
        int status = urb->status;
 
@@ -276,13 +923,7 @@ static void mos7720_bulk_in_callback(struct urb *urb)
                return;
        }
 
-       mos7720_port = urb->context;
-       if (!mos7720_port) {
-               dbg("NULL mos7720_port pointer");
-               return ;
-       }
-
-       port = mos7720_port->port;
+       port = urb->context;
 
        dbg("Entering...%s", __func__);
 
@@ -332,8 +973,6 @@ static void mos7720_bulk_out_data_callback(struct urb *urb)
                return ;
        }
 
-       dbg("Entering .........");
-
        tty = tty_port_tty_get(&mos7720_port->port->port);
 
        if (tty && mos7720_port->open)
@@ -424,7 +1063,6 @@ static int mos7720_open(struct tty_struct *tty, struct usb_serial_port *port)
        struct usb_serial *serial;
        struct usb_serial_port *port0;
        struct urb *urb;
-       struct moschip_serial *mos7720_serial;
        struct moschip_port *mos7720_port;
        int response;
        int port_number;
@@ -440,11 +1078,6 @@ static int mos7720_open(struct tty_struct *tty, struct usb_serial_port *port)
 
        port0 = serial->port[0];
 
-       mos7720_serial = usb_get_serial_data(serial);
-
-       if (mos7720_serial == NULL || port0 == NULL)
-               return -ENODEV;
-
        usb_clear_halt(serial->dev, port->write_urb->pipe);
        usb_clear_halt(serial->dev, port->read_urb->pipe);
 
@@ -549,43 +1182,6 @@ static int mos7720_open(struct tty_struct *tty, struct usb_serial_port *port)
        data = 0x0c;
        send_mos_cmd(serial, MOS_WRITE, port_number, 0x01, &data);
 
-       /* see if we've set up our endpoint info yet   *
-        * (can't set it up in mos7720_startup as the  *
-        * structures were not set up at that time.)   */
-       if (!mos7720_serial->interrupt_started) {
-               dbg("Interrupt buffer NULL !!!");
-
-               /* not set up yet, so do it now */
-               mos7720_serial->interrupt_started = 1;
-
-               dbg("To Submit URB !!!");
-
-               /* set up our interrupt urb */
-               usb_fill_int_urb(port0->interrupt_in_urb, serial->dev,
-                        usb_rcvintpipe(serial->dev,
-                               port->interrupt_in_endpointAddress),
-                        port0->interrupt_in_buffer,
-                        port0->interrupt_in_urb->transfer_buffer_length,
-                        mos7720_interrupt_callback, mos7720_port,
-                        port0->interrupt_in_urb->interval);
-
-               /* start interrupt read for this mos7720 this interrupt *
-                * will continue as long as the mos7720 is connected    */
-               dbg("Submit URB over !!!");
-               response = usb_submit_urb(port0->interrupt_in_urb, GFP_KERNEL);
-               if (response)
-                       dev_err(&port->dev,
-                               "%s - Error %d submitting control urb\n",
-                               __func__, response);
-       }
-
-       /* set up our bulk in urb */
-       usb_fill_bulk_urb(port->read_urb, serial->dev,
-                         usb_rcvbulkpipe(serial->dev,
-                               port->bulk_in_endpointAddress),
-                         port->bulk_in_buffer,
-                         port->read_urb->transfer_buffer_length,
-                         mos7720_bulk_in_callback, mos7720_port);
        response = usb_submit_urb(port->read_urb, GFP_KERNEL);
        if (response)
                dev_err(&port->dev, "%s - Error %d submitting read urb\n",
@@ -897,6 +1493,7 @@ static void mos7720_unthrottle(struct tty_struct *tty)
        }
 }
 
+/* FIXME: this function does not work */
 static int set_higher_rates(struct moschip_port *mos7720_port,
                            unsigned int baud)
 {
@@ -939,6 +1536,7 @@ static int set_higher_rates(struct moschip_port *mos7720_port,
         *              Set for higher rates           *
         ***********************************************/
 
+       /* writing baud rate verbatum into uart clock field clearly not right */
        data = baud * 0x10;
        send_mos_cmd(serial, MOS_WRITE, MOS_MAX_PORT, port_number + 1, &data);
 
@@ -1308,7 +1906,7 @@ static void mos7720_set_termios(struct tty_struct *tty,
                return;
        }
 
-       dbg("setting termios - ASPIRE");
+       dbg("%s\n", "setting termios - ASPIRE");
 
        cflag = tty->termios->c_cflag;
 
@@ -1326,7 +1924,7 @@ static void mos7720_set_termios(struct tty_struct *tty,
        change_port_settings(tty, mos7720_port, old_termios);
 
        if (!port->read_urb) {
-               dbg("URB KILLED !!!!!");
+               dbg("%s", "URB KILLED !!!!!");
                return;
        }
 
@@ -1590,12 +2188,12 @@ static int mos7720_ioctl(struct tty_struct *tty, struct file *file,
 
 static int mos7720_startup(struct usb_serial *serial)
 {
-       struct moschip_serial *mos7720_serial;
        struct moschip_port *mos7720_port;
        struct usb_device *dev;
        int i;
        char data;
        u16 product = le16_to_cpu(serial->dev->descriptor.idProduct);
+       int ret_val;
 
        dbg("%s: Entering ..........", __func__);
 
@@ -1606,15 +2204,6 @@ static int mos7720_startup(struct usb_serial *serial)
 
        dev = serial->dev;
 
-       /* create our private serial structure */
-       mos7720_serial = kzalloc(sizeof(struct moschip_serial), GFP_KERNEL);
-       if (mos7720_serial == NULL) {
-               dev_err(&dev->dev, "%s - Out of memory\n", __func__);
-               return -ENOMEM;
-       }
-
-       usb_set_serial_data(serial, mos7720_serial);
-
        /*
         * The 7715 uses the first bulk in/out endpoint pair for the parallel
         * port, and the second for the serial port.  Because the usbserial core
@@ -1638,16 +2227,12 @@ static int mos7720_startup(struct usb_serial *serial)
                serial->port[1]->interrupt_in_buffer = NULL;
        }
 
-       /* we set up the pointers to the endpoints in the mos7720_open *
-        * function, as the structures aren't created yet.             */
 
-       /* set up port private structures */
+       /* set up serial port private structures */
        for (i = 0; i < serial->num_ports; ++i) {
                mos7720_port = kzalloc(sizeof(struct moschip_port), GFP_KERNEL);
                if (mos7720_port == NULL) {
                        dev_err(&dev->dev, "%s - Out of memory\n", __func__);
-                       usb_set_serial_data(serial, NULL);
-                       kfree(mos7720_serial);
                        return -ENOMEM;
                }
 
@@ -1669,6 +2254,20 @@ static int mos7720_startup(struct usb_serial *serial)
        usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                        (__u8)0x03, 0x00, 0x01, 0x00, NULL, 0x00, 5*HZ);
 
+       /* start the interrupt urb */
+       ret_val = usb_submit_urb(serial->port[0]->interrupt_in_urb, GFP_KERNEL);
+       if (ret_val)
+               dev_err(&dev->dev,
+                       "%s - Error %d submitting control urb\n",
+                       __func__, ret_val);
+
+#ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
+       if (product == MOSCHIP_DEVICE_ID_7715) {
+               ret_val = mos7715_parport_init(serial);
+               if (ret_val < 0)
+                       return ret_val;
+       }
+#endif
        /* LSR For Port 1 */
        send_mos_cmd(serial, MOS_READ, 0x00, UART_LSR, &data);
        dbg("LSR:%x", data);
@@ -1684,12 +2283,47 @@ static void mos7720_release(struct usb_serial *serial)
 {
        int i;
 
+#ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
+       /* close the parallel port */
+
+       if (le16_to_cpu(serial->dev->descriptor.idProduct)
+           == MOSCHIP_DEVICE_ID_7715) {
+               struct urbtracker *urbtrack;
+               unsigned long flags;
+               struct mos7715_parport *mos_parport =
+                       usb_get_serial_data(serial);
+
+               /* prevent NULL ptr dereference in port callbacks */
+               spin_lock(&release_lock);
+               mos_parport->pp->private_data = NULL;
+               spin_unlock(&release_lock);
+
+               /* wait for synchronous usb calls to return */
+               if (mos_parport->msg_pending)
+                       wait_for_completion_timeout(&mos_parport->syncmsg_compl,
+                                                   MOS_WDR_TIMEOUT);
+
+               parport_remove_port(mos_parport->pp);
+               usb_set_serial_data(serial, NULL);
+               mos_parport->serial = NULL;
+
+               /* if tasklet currently scheduled, wait for it to complete */
+               tasklet_kill(&mos_parport->urb_tasklet);
+
+               /* unlink any urbs sent by the tasklet  */
+               spin_lock_irqsave(&mos_parport->listlock, flags);
+               list_for_each_entry(urbtrack,
+                                   &mos_parport->active_urbs,
+                                   urblist_entry)
+                       usb_unlink_urb(urbtrack->urb);
+               spin_unlock_irqrestore(&mos_parport->listlock, flags);
+
+               kref_put(&mos_parport->ref_count, destroy_mos_parport);
+       }
+#endif
        /* free private structure allocated for serial port */
        for (i = 0; i < serial->num_ports; ++i)
                kfree(usb_get_serial_port_data(serial->port[i]));
-
-       /* free private structure allocated for serial device */
-       kfree(usb_get_serial_data(serial));
 }
 
 static struct usb_driver usb_driver = {