#include "ice.h"
 #include "ice_lib.h"
-#include <linux/tty_driver.h>
 
 /**
- * ice_gnss_do_write - Write data to internal GNSS
+ * ice_gnss_do_write - Write data to internal GNSS receiver
  * @pf: board private structure
  * @buf: command buffer
  * @size: command buffer size
  *
  * Write UBX command data to the GNSS receiver
+ *
+ * Return:
+ * * number of bytes written - success
+ * * negative - error code
  */
 static unsigned int
 ice_gnss_do_write(struct ice_pf *pf, unsigned char *buf, unsigned int size)
                                                write_work);
        struct ice_pf *pf = gnss->back;
 
+       if (!pf)
+               return;
+
+       if (!test_bit(ICE_FLAG_GNSS, pf->flags))
+               return;
+
        if (!list_empty(&gnss->queue)) {
                struct gnss_write_buf *write_buf = NULL;
                unsigned int bytes;
  * ice_gnss_read - Read data from internal GNSS module
  * @work: GNSS read work structure
  *
- * Read the data from internal GNSS receiver, number of bytes read will be
- * returned in *read_data parameter.
+ * Read the data from internal GNSS receiver, write it to gnss_dev.
  */
 static void ice_gnss_read(struct kthread_work *work)
 {
        struct gnss_serial *gnss = container_of(work, struct gnss_serial,
                                                read_work.work);
+       unsigned int i, bytes_read, data_len, count;
        struct ice_aqc_link_topo_addr link_topo;
-       unsigned int i, bytes_read, data_len;
-       struct tty_port *port;
        struct ice_pf *pf;
        struct ice_hw *hw;
        __be16 data_len_b;
        int err = 0;
 
        pf = gnss->back;
-       if (!pf || !gnss->tty || !gnss->tty->port) {
+       if (!pf) {
                err = -EFAULT;
                goto exit;
        }
 
-       hw = &pf->hw;
-       port = gnss->tty->port;
+       if (!test_bit(ICE_FLAG_GNSS, pf->flags))
+               return;
 
+       hw = &pf->hw;
        buf = (char *)get_zeroed_page(GFP_KERNEL);
        if (!buf) {
                err = -ENOMEM;
        }
 
        data_len = min_t(typeof(data_len), data_len, PAGE_SIZE);
-       data_len = tty_buffer_request_room(port, data_len);
        if (!data_len) {
                err = -ENOMEM;
                goto exit_buf;
                        goto exit_buf;
        }
 
-       /* Send the data to the tty layer for users to read. This doesn't
-        * actually push the data through unless tty->low_latency is set.
-        */
-       tty_insert_flip_string(port, buf, i);
-       tty_flip_buffer_push(port);
-
+       count = gnss_insert_raw(pf->gnss_dev, buf, i);
+       if (count != i)
+               dev_warn(ice_pf_to_dev(pf),
+                        "gnss_insert_raw ret=%d size=%d\n",
+                        count, i);
 exit_buf:
        free_page((unsigned long)buf);
        kthread_queue_delayed_work(gnss->kworker, &gnss->read_work,
 }
 
 /**
- * ice_gnss_struct_init - Initialize GNSS structure for the TTY
+ * ice_gnss_struct_init - Initialize GNSS receiver
  * @pf: Board private structure
- * @index: TTY device index
+ *
+ * Initialize GNSS structures and workers.
+ *
+ * Return:
+ * * pointer to initialized gnss_serial struct - success
+ * * NULL - error
  */
-static struct gnss_serial *ice_gnss_struct_init(struct ice_pf *pf, int index)
+static struct gnss_serial *ice_gnss_struct_init(struct ice_pf *pf)
 {
        struct device *dev = ice_pf_to_dev(pf);
        struct kthread_worker *kworker;
        if (!gnss)
                return NULL;
 
-       mutex_init(&gnss->gnss_mutex);
-       gnss->open_count = 0;
        gnss->back = pf;
-       pf->gnss_serial[index] = gnss;
+       pf->gnss_serial = gnss;
 
        kthread_init_delayed_work(&gnss->read_work, ice_gnss_read);
        INIT_LIST_HEAD(&gnss->queue);
        kthread_init_work(&gnss->write_work, ice_gnss_write_pending);
-       /* Allocate a kworker for handling work required for the GNSS TTY
-        * writes.
-        */
        kworker = kthread_create_worker(0, "ice-gnss-%s", dev_name(dev));
        if (IS_ERR(kworker)) {
                kfree(gnss);
 }
 
 /**
- * ice_gnss_tty_open - Initialize GNSS structures on TTY device open
- * @tty: pointer to the tty_struct
- * @filp: pointer to the file
+ * ice_gnss_open - Open GNSS device
+ * @gdev: pointer to the gnss device struct
+ *
+ * Open GNSS device and start filling the read buffer for consumer.
  *
- * This routine is mandatory. If this routine is not filled in, the attempted
- * open will fail with ENODEV.
+ * Return:
+ * * 0 - success
+ * * negative - error code
  */
-static int ice_gnss_tty_open(struct tty_struct *tty, struct file *filp)
+static int ice_gnss_open(struct gnss_device *gdev)
 {
+       struct ice_pf *pf = gnss_get_drvdata(gdev);
        struct gnss_serial *gnss;
-       struct ice_pf *pf;
 
-       pf = (struct ice_pf *)tty->driver->driver_state;
        if (!pf)
                return -EFAULT;
 
-       /* Clear the pointer in case something fails */
-       tty->driver_data = NULL;
-
-       /* Get the serial object associated with this tty pointer */
-       gnss = pf->gnss_serial[tty->index];
-       if (!gnss) {
-               /* Initialize GNSS struct on the first device open */
-               gnss = ice_gnss_struct_init(pf, tty->index);
-               if (!gnss)
-                       return -ENOMEM;
-       }
+       if (!test_bit(ICE_FLAG_GNSS, pf->flags))
+               return -EFAULT;
 
-       mutex_lock(&gnss->gnss_mutex);
+       gnss = pf->gnss_serial;
+       if (!gnss)
+               return -ENODEV;
 
-       /* Save our structure within the tty structure */
-       tty->driver_data = gnss;
-       gnss->tty = tty;
-       gnss->open_count++;
        kthread_queue_delayed_work(gnss->kworker, &gnss->read_work, 0);
 
-       mutex_unlock(&gnss->gnss_mutex);
-
        return 0;
 }
 
 /**
- * ice_gnss_tty_close - Cleanup GNSS structures on tty device close
- * @tty: pointer to the tty_struct
- * @filp: pointer to the file
+ * ice_gnss_close - Close GNSS device
+ * @gdev: pointer to the gnss device struct
+ *
+ * Close GNSS device, cancel worker, stop filling the read buffer.
  */
-static void ice_gnss_tty_close(struct tty_struct *tty, struct file *filp)
+static void ice_gnss_close(struct gnss_device *gdev)
 {
-       struct gnss_serial *gnss = tty->driver_data;
-       struct ice_pf *pf;
-
-       if (!gnss)
-               return;
+       struct ice_pf *pf = gnss_get_drvdata(gdev);
+       struct gnss_serial *gnss;
 
-       pf = (struct ice_pf *)tty->driver->driver_state;
        if (!pf)
                return;
 
-       mutex_lock(&gnss->gnss_mutex);
-
-       if (!gnss->open_count) {
-               /* Port was never opened */
-               dev_err(ice_pf_to_dev(pf), "GNSS port not opened\n");
-               goto exit;
-       }
+       gnss = pf->gnss_serial;
+       if (!gnss)
+               return;
 
-       gnss->open_count--;
-       if (gnss->open_count <= 0) {
-               /* Port is in shutdown state */
-               kthread_cancel_delayed_work_sync(&gnss->read_work);
-       }
-exit:
-       mutex_unlock(&gnss->gnss_mutex);
+       kthread_cancel_work_sync(&gnss->write_work);
+       kthread_cancel_delayed_work_sync(&gnss->read_work);
 }
 
 /**
- * ice_gnss_tty_write - Write GNSS data
- * @tty: pointer to the tty_struct
+ * ice_gnss_write - Write to GNSS device
+ * @gdev: pointer to the gnss device struct
  * @buf: pointer to the user data
- * @count: the number of characters queued to be sent to the HW
+ * @count: size of the buffer to be sent to the GNSS device
  *
- * The write function call is called by the user when there is data to be sent
- * to the hardware. First the tty core receives the call, and then it passes the
- * data on to the tty driver's write function. The tty core also tells the tty
- * driver the size of the data being sent.
- * If any errors happen during the write call, a negative error value should be
- * returned instead of the number of characters queued to be written.
+ * Return:
+ * * number of written bytes - success
+ * * negative - error code
  */
 static int
-ice_gnss_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
+ice_gnss_write(struct gnss_device *gdev, const unsigned char *buf,
+              size_t count)
 {
+       struct ice_pf *pf = gnss_get_drvdata(gdev);
        struct gnss_write_buf *write_buf;
        struct gnss_serial *gnss;
        unsigned char *cmd_buf;
-       struct ice_pf *pf;
        int err = count;
 
        /* We cannot write a single byte using our I2C implementation. */
        if (count <= 1 || count > ICE_GNSS_TTY_WRITE_BUF)
                return -EINVAL;
 
-       gnss = tty->driver_data;
-       if (!gnss)
-               return -EFAULT;
-
-       pf = (struct ice_pf *)tty->driver->driver_state;
        if (!pf)
                return -EFAULT;
 
-       /* Only allow to write on TTY 0 */
-       if (gnss != pf->gnss_serial[0])
-               return -EIO;
-
-       mutex_lock(&gnss->gnss_mutex);
+       if (!test_bit(ICE_FLAG_GNSS, pf->flags))
+               return -EFAULT;
 
-       if (!gnss->open_count) {
-               err = -EINVAL;
-               goto exit;
-       }
+       gnss = pf->gnss_serial;
+       if (!gnss)
+               return -ENODEV;
 
        cmd_buf = kcalloc(count, sizeof(*buf), GFP_KERNEL);
-       if (!cmd_buf) {
-               err = -ENOMEM;
-               goto exit;
-       }
+       if (!cmd_buf)
+               return -ENOMEM;
 
        memcpy(cmd_buf, buf, count);
-
-       /* Send the data out to a hardware port */
        write_buf = kzalloc(sizeof(*write_buf), GFP_KERNEL);
        if (!write_buf) {
                kfree(cmd_buf);
-               err = -ENOMEM;
-               goto exit;
+               return -ENOMEM;
        }
 
        write_buf->buf = cmd_buf;
        INIT_LIST_HEAD(&write_buf->queue);
        list_add_tail(&write_buf->queue, &gnss->queue);
        kthread_queue_work(gnss->kworker, &gnss->write_work);
-exit:
-       mutex_unlock(&gnss->gnss_mutex);
+
        return err;
 }
 
+static const struct gnss_operations ice_gnss_ops = {
+       .open = ice_gnss_open,
+       .close = ice_gnss_close,
+       .write_raw = ice_gnss_write,
+};
+
 /**
- * ice_gnss_tty_write_room - Returns the numbers of characters to be written.
- * @tty: pointer to the tty_struct
+ * ice_gnss_register - Register GNSS receiver
+ * @pf: Board private structure
+ *
+ * Allocate and register GNSS receiver in the Linux GNSS subsystem.
  *
- * This routine returns the numbers of characters the tty driver will accept
- * for queuing to be written or 0 if either the TTY is not open or user
- * tries to write to the TTY other than the first.
+ * Return:
+ * * 0 - success
+ * * negative - error code
  */
-static unsigned int ice_gnss_tty_write_room(struct tty_struct *tty)
+static int ice_gnss_register(struct ice_pf *pf)
 {
-       struct gnss_serial *gnss = tty->driver_data;
-
-       /* Only allow to write on TTY 0 */
-       if (!gnss || gnss != gnss->back->gnss_serial[0])
-               return 0;
-
-       mutex_lock(&gnss->gnss_mutex);
+       struct gnss_device *gdev;
+       int ret;
+
+       gdev = gnss_allocate_device(ice_pf_to_dev(pf));
+       if (!gdev) {
+               dev_err(ice_pf_to_dev(pf),
+                       "gnss_allocate_device returns NULL\n");
+               return -ENOMEM;
+       }
 
-       if (!gnss->open_count) {
-               mutex_unlock(&gnss->gnss_mutex);
-               return 0;
+       gdev->ops = &ice_gnss_ops;
+       gdev->type = GNSS_TYPE_UBX;
+       gnss_set_drvdata(gdev, pf);
+       ret = gnss_register_device(gdev);
+       if (ret) {
+               dev_err(ice_pf_to_dev(pf), "gnss_register_device err=%d\n",
+                       ret);
+               gnss_put_device(gdev);
+       } else {
+               pf->gnss_dev = gdev;
        }
 
-       mutex_unlock(&gnss->gnss_mutex);
-       return ICE_GNSS_TTY_WRITE_BUF;
+       return ret;
 }
 
-static const struct tty_operations tty_gps_ops = {
-       .open =         ice_gnss_tty_open,
-       .close =        ice_gnss_tty_close,
-       .write =        ice_gnss_tty_write,
-       .write_room =   ice_gnss_tty_write_room,
-};
-
 /**
- * ice_gnss_create_tty_driver - Create a TTY driver for GNSS
+ * ice_gnss_deregister - Deregister GNSS receiver
  * @pf: Board private structure
+ *
+ * Deregister GNSS receiver from the Linux GNSS subsystem,
+ * release its resources.
  */
-static struct tty_driver *ice_gnss_create_tty_driver(struct ice_pf *pf)
+static void ice_gnss_deregister(struct ice_pf *pf)
 {
-       struct device *dev = ice_pf_to_dev(pf);
-       const int ICE_TTYDRV_NAME_MAX = 14;
-       struct tty_driver *tty_driver;
-       char *ttydrv_name;
-       unsigned int i;
-       int err;
-
-       tty_driver = tty_alloc_driver(ICE_GNSS_TTY_MINOR_DEVICES,
-                                     TTY_DRIVER_REAL_RAW);
-       if (IS_ERR(tty_driver)) {
-               dev_err(dev, "Failed to allocate memory for GNSS TTY\n");
-               return NULL;
-       }
-
-       ttydrv_name = kzalloc(ICE_TTYDRV_NAME_MAX, GFP_KERNEL);
-       if (!ttydrv_name) {
-               tty_driver_kref_put(tty_driver);
-               return NULL;
+       if (pf->gnss_dev) {
+               gnss_deregister_device(pf->gnss_dev);
+               gnss_put_device(pf->gnss_dev);
+               pf->gnss_dev = NULL;
        }
-
-       snprintf(ttydrv_name, ICE_TTYDRV_NAME_MAX, "ttyGNSS_%02x%02x_",
-                (u8)pf->pdev->bus->number, (u8)PCI_SLOT(pf->pdev->devfn));
-
-       /* Initialize the tty driver*/
-       tty_driver->owner = THIS_MODULE;
-       tty_driver->driver_name = dev_driver_string(dev);
-       tty_driver->name = (const char *)ttydrv_name;
-       tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
-       tty_driver->subtype = SERIAL_TYPE_NORMAL;
-       tty_driver->init_termios = tty_std_termios;
-       tty_driver->init_termios.c_iflag &= ~INLCR;
-       tty_driver->init_termios.c_iflag |= IGNCR;
-       tty_driver->init_termios.c_oflag &= ~OPOST;
-       tty_driver->init_termios.c_lflag &= ~ICANON;
-       tty_driver->init_termios.c_cflag &= ~(CSIZE | CBAUD | CBAUDEX);
-       /* baud rate 9600 */
-       tty_termios_encode_baud_rate(&tty_driver->init_termios, 9600, 9600);
-       tty_driver->driver_state = pf;
-       tty_set_operations(tty_driver, &tty_gps_ops);
-
-       for (i = 0; i < ICE_GNSS_TTY_MINOR_DEVICES; i++) {
-               pf->gnss_tty_port[i] = kzalloc(sizeof(*pf->gnss_tty_port[i]),
-                                              GFP_KERNEL);
-               if (!pf->gnss_tty_port[i])
-                       goto err_out;
-
-               pf->gnss_serial[i] = NULL;
-
-               tty_port_init(pf->gnss_tty_port[i]);
-               tty_port_link_device(pf->gnss_tty_port[i], tty_driver, i);
-       }
-
-       err = tty_register_driver(tty_driver);
-       if (err) {
-               dev_err(dev, "Failed to register TTY driver err=%d\n", err);
-               goto err_out;
-       }
-
-       for (i = 0; i < ICE_GNSS_TTY_MINOR_DEVICES; i++)
-               dev_info(dev, "%s%d registered\n", ttydrv_name, i);
-
-       return tty_driver;
-
-err_out:
-       while (i--) {
-               tty_port_destroy(pf->gnss_tty_port[i]);
-               kfree(pf->gnss_tty_port[i]);
-       }
-       kfree(ttydrv_name);
-       tty_driver_kref_put(pf->ice_gnss_tty_driver);
-
-       return NULL;
 }
 
 /**
- * ice_gnss_init - Initialize GNSS TTY support
+ * ice_gnss_init - Initialize GNSS support
  * @pf: Board private structure
  */
 void ice_gnss_init(struct ice_pf *pf)
 {
-       struct tty_driver *tty_driver;
+       int ret;
 
-       tty_driver = ice_gnss_create_tty_driver(pf);
-       if (!tty_driver)
+       pf->gnss_serial = ice_gnss_struct_init(pf);
+       if (!pf->gnss_serial)
                return;
 
-       pf->ice_gnss_tty_driver = tty_driver;
-
-       set_bit(ICE_FLAG_GNSS, pf->flags);
-       dev_info(ice_pf_to_dev(pf), "GNSS TTY init successful\n");
+       ret = ice_gnss_register(pf);
+       if (!ret) {
+               set_bit(ICE_FLAG_GNSS, pf->flags);
+               dev_info(ice_pf_to_dev(pf), "GNSS init successful\n");
+       } else {
+               ice_gnss_exit(pf);
+               dev_err(ice_pf_to_dev(pf), "GNSS init failure\n");
+       }
 }
 
 /**
  */
 void ice_gnss_exit(struct ice_pf *pf)
 {
-       unsigned int i;
+       ice_gnss_deregister(pf);
+       clear_bit(ICE_FLAG_GNSS, pf->flags);
 
-       if (!test_bit(ICE_FLAG_GNSS, pf->flags) || !pf->ice_gnss_tty_driver)
-               return;
-
-       for (i = 0; i < ICE_GNSS_TTY_MINOR_DEVICES; i++) {
-               if (pf->gnss_tty_port[i]) {
-                       tty_port_destroy(pf->gnss_tty_port[i]);
-                       kfree(pf->gnss_tty_port[i]);
-               }
+       if (pf->gnss_serial) {
+               struct gnss_serial *gnss = pf->gnss_serial;
 
-               if (pf->gnss_serial[i]) {
-                       struct gnss_serial *gnss = pf->gnss_serial[i];
+               kthread_cancel_work_sync(&gnss->write_work);
+               kthread_cancel_delayed_work_sync(&gnss->read_work);
+               kthread_destroy_worker(gnss->kworker);
+               gnss->kworker = NULL;
 
-                       kthread_cancel_work_sync(&gnss->write_work);
-                       kthread_cancel_delayed_work_sync(&gnss->read_work);
-                       kfree(gnss);
-                       pf->gnss_serial[i] = NULL;
-               }
+               kfree(gnss);
+               pf->gnss_serial = NULL;
        }
-
-       tty_unregister_driver(pf->ice_gnss_tty_driver);
-       kfree(pf->ice_gnss_tty_driver->name);
-       tty_driver_kref_put(pf->ice_gnss_tty_driver);
-       pf->ice_gnss_tty_driver = NULL;
 }
 
 /**