Message-Id: <20230119005836.2068818-1-anthony.l.nguyen@intel.com>
Date:   Wed, 18 Jan 2023 16:58:36 -0800
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com
Cc:     Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
        netdev@...r.kernel.org, anthony.l.nguyen@...el.com,
        johan@...nel.org, gregkh@...uxfoundation.org, jirislaby@...nel.org,
        Alexander Lobakin <alexandr.lobakin@...el.com>,
        Karol Kolacinski <karol.kolacinski@...el.com>,
        Michal Michalik <michal.michalik@...el.com>,
        Gurucharan G <gurucharanx.g@...el.com>
Subject: [PATCH net-next v2 1/1] ice: use GNSS subsystem instead of TTY

From: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>

Previously support for GNSS was implemented as a TTY driver, it allowed
to access GNSS receiver on /dev/ttyGNSS_<bus><func>.

Use generic GNSS subsystem API instead of implementing own TTY driver.
The receiver is accessible on /dev/gnss<id>. In case of multiple receivers
in the OS, correct device can be found by enumerating either:
- /sys/class/net/<eth port>/device/gnss/
- /sys/class/gnss/gnss<id>/device/

Using GNSS subsystem is superior to implementing own TTY driver, as the
GNSS subsystem was designed solely for this purpose. It also implements
TTY driver but in a common and defined way.

>From user perspective, there is no difference in communicating with a
device, except new path to the device shall be used. The device will
provide same information to the userspace as the old one, and can be used
in the same way, i.e.:
old # gpsmon /dev/ttyGNSS_2100_0
new # gpsmon /dev/gnss0
There is no other impact on userspace tools.

User expecting onboard GNSS receiver support is required to enable
CONFIG_GNSS=y/m in kernel config.

Reviewed-by: Alexander Lobakin <alexandr.lobakin@...el.com>
Signed-off-by: Karol Kolacinski <karol.kolacinski@...el.com>
Signed-off-by: Michal Michalik <michal.michalik@...el.com>
Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>
Tested-by: Gurucharan G <gurucharanx.g@...el.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
v2: 
- Add more info into commit message
v1: https://lore.kernel.org/netdev/20230113214852.970949-1-anthony.l.nguyen@intel.com/

Based on feedback from:
https://lore.kernel.org/netdev/20220829220049.333434-4-anthony.l.nguyen@intel.com/

 .../device_drivers/ethernet/intel/ice.rst     |  16 +-
 drivers/net/ethernet/intel/Kconfig            |   3 +
 drivers/net/ethernet/intel/ice/Makefile       |   2 +-
 drivers/net/ethernet/intel/ice/ice.h          |   6 +-
 drivers/net/ethernet/intel/ice/ice_gnss.c     | 377 +++++++-----------
 drivers/net/ethernet/intel/ice/ice_gnss.h     |  18 +-
 6 files changed, 158 insertions(+), 264 deletions(-)

diff --git a/Documentation/networking/device_drivers/ethernet/intel/ice.rst b/Documentation/networking/device_drivers/ethernet/intel/ice.rst
index dc2e60ced927..1aa029d08cb1 100644
--- a/Documentation/networking/device_drivers/ethernet/intel/ice.rst
+++ b/Documentation/networking/device_drivers/ethernet/intel/ice.rst
@@ -901,15 +901,17 @@ To enable/disable UDP Segmentation Offload, issue the following command::
 
   # ethtool -K <ethX> tx-udp-segmentation [off|on]
 
+
 GNSS module
 -----------
-Allows user to read messages from the GNSS module and write supported commands.
-If the module is physically present, driver creates 2 TTYs for each supported
-device in /dev, ttyGNSS_<device>:<function>_0 and _1. First one (_0) is RW and
-the second one is RO.
-The protocol of write commands is dependent on the GNSS module as the driver
-writes raw bytes from the TTY to the GNSS i2c. Please refer to the module
-documentation for details.
+Requires kernel compiled with CONFIG_GNSS=y or CONFIG_GNSS=m.
+Allows user to read messages from the GNSS hardware module and write supported
+commands. If the module is physically present, a GNSS device is spawned:
+``/dev/gnss<id>``.
+The protocol of write command is dependent on the GNSS hardware module as the
+driver writes raw bytes by the GNSS object to the receiver through i2c. Please
+refer to the hardware GNSS module documentation for configuration details.
+
 
 Performance Optimization
 ========================
diff --git a/drivers/net/ethernet/intel/Kconfig b/drivers/net/ethernet/intel/Kconfig
index 3facb55b7161..a3c84bf05e44 100644
--- a/drivers/net/ethernet/intel/Kconfig
+++ b/drivers/net/ethernet/intel/Kconfig
@@ -337,6 +337,9 @@ config ICE_HWTS
 	  the PTP clock driver precise cross-timestamp ioctl
 	  (PTP_SYS_OFFSET_PRECISE).
 
+config ICE_GNSS
+	def_bool GNSS = y || GNSS = ICE
+
 config FM10K
 	tristate "Intel(R) FM10000 Ethernet Switch Host Interface Support"
 	default n
diff --git a/drivers/net/ethernet/intel/ice/Makefile b/drivers/net/ethernet/intel/ice/Makefile
index 9183d480b70b..060d8f2b4953 100644
--- a/drivers/net/ethernet/intel/ice/Makefile
+++ b/drivers/net/ethernet/intel/ice/Makefile
@@ -42,8 +42,8 @@ ice-$(CONFIG_PCI_IOV) +=	\
 	ice_vf_vsi_vlan_ops.o	\
 	ice_vf_lib.o
 ice-$(CONFIG_PTP_1588_CLOCK) += ice_ptp.o ice_ptp_hw.o
-ice-$(CONFIG_TTY) += ice_gnss.o
 ice-$(CONFIG_DCB) += ice_dcb.o ice_dcb_nl.o ice_dcb_lib.o
 ice-$(CONFIG_RFS_ACCEL) += ice_arfs.o
 ice-$(CONFIG_XDP_SOCKETS) += ice_xsk.o
 ice-$(CONFIG_ICE_SWITCHDEV) += ice_eswitch.o
+ice-$(CONFIG_ICE_GNSS) += ice_gnss.o
diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
index 2f0b604abc5e..ae93ae488bc2 100644
--- a/drivers/net/ethernet/intel/ice/ice.h
+++ b/drivers/net/ethernet/intel/ice/ice.h
@@ -39,6 +39,7 @@
 #include <linux/avf/virtchnl.h>
 #include <linux/cpu_rmap.h>
 #include <linux/dim.h>
+#include <linux/gnss.h>
 #include <net/pkt_cls.h>
 #include <net/tc_act/tc_mirred.h>
 #include <net/tc_act/tc_gact.h>
@@ -565,9 +566,8 @@ struct ice_pf {
 	struct mutex adev_mutex;	/* lock to protect aux device access */
 	u32 msg_enable;
 	struct ice_ptp ptp;
-	struct tty_driver *ice_gnss_tty_driver;
-	struct tty_port *gnss_tty_port[ICE_GNSS_TTY_MINOR_DEVICES];
-	struct gnss_serial *gnss_serial[ICE_GNSS_TTY_MINOR_DEVICES];
+	struct gnss_serial *gnss_serial;
+	struct gnss_device *gnss_dev;
 	u16 num_rdma_msix;		/* Total MSIX vectors for RDMA driver */
 	u16 rdma_base_vector;
 
diff --git a/drivers/net/ethernet/intel/ice/ice_gnss.c b/drivers/net/ethernet/intel/ice/ice_gnss.c
index 43e199b5b513..8dec748bb53a 100644
--- a/drivers/net/ethernet/intel/ice/ice_gnss.c
+++ b/drivers/net/ethernet/intel/ice/ice_gnss.c
@@ -3,15 +3,18 @@
 
 #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)
@@ -82,6 +85,12 @@ static void ice_gnss_write_pending(struct kthread_work *work)
 						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;
@@ -102,16 +111,14 @@ static void ice_gnss_write_pending(struct kthread_work *work)
  * 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;
@@ -120,14 +127,15 @@ static void ice_gnss_read(struct kthread_work *work)
 	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;
@@ -159,7 +167,6 @@ static void ice_gnss_read(struct kthread_work *work)
 	}
 
 	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;
@@ -179,12 +186,11 @@ static void ice_gnss_read(struct kthread_work *work)
 			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,
@@ -195,11 +201,16 @@ static void ice_gnss_read(struct kthread_work *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;
@@ -209,17 +220,12 @@ static struct gnss_serial *ice_gnss_struct_init(struct ice_pf *pf, int index)
 	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);
@@ -232,140 +238,100 @@ static struct gnss_serial *ice_gnss_struct_init(struct ice_pf *pf, int index)
 }
 
 /**
- * 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;
@@ -373,141 +339,89 @@ ice_gnss_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
 	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");
+	}
 }
 
 /**
@@ -516,31 +430,20 @@ void ice_gnss_init(struct ice_pf *pf)
  */
 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;
 }
 
 /**
diff --git a/drivers/net/ethernet/intel/ice/ice_gnss.h b/drivers/net/ethernet/intel/ice/ice_gnss.h
index f454dd1d9285..31db0701d13f 100644
--- a/drivers/net/ethernet/intel/ice/ice_gnss.h
+++ b/drivers/net/ethernet/intel/ice/ice_gnss.h
@@ -4,15 +4,8 @@
 #ifndef _ICE_GNSS_H_
 #define _ICE_GNSS_H_
 
-#include <linux/tty.h>
-#include <linux/tty_flip.h>
-
 #define ICE_E810T_GNSS_I2C_BUS		0x2
 #define ICE_GNSS_TIMER_DELAY_TIME	(HZ / 10) /* 0.1 second per message */
-/* Create 2 minor devices, both using the same GNSS module. First one is RW,
- * second one RO.
- */
-#define ICE_GNSS_TTY_MINOR_DEVICES	2
 #define ICE_GNSS_TTY_WRITE_BUF		250
 #define ICE_MAX_I2C_DATA_SIZE		FIELD_MAX(ICE_AQC_I2C_DATA_SIZE_M)
 #define ICE_MAX_I2C_WRITE_BYTES		4
@@ -36,13 +29,9 @@ struct gnss_write_buf {
 	unsigned char *buf;
 };
 
-
 /**
  * struct gnss_serial - data used to initialize GNSS TTY port
  * @back: back pointer to PF
- * @tty: pointer to the tty for this device
- * @open_count: number of times this port has been opened
- * @gnss_mutex: gnss_mutex used to protect GNSS serial operations
  * @kworker: kwork thread for handling periodic work
  * @read_work: read_work function for handling GNSS reads
  * @write_work: write_work function for handling GNSS writes
@@ -50,16 +39,13 @@ struct gnss_write_buf {
  */
 struct gnss_serial {
 	struct ice_pf *back;
-	struct tty_struct *tty;
-	int open_count;
-	struct mutex gnss_mutex; /* protects GNSS serial structure */
 	struct kthread_worker *kworker;
 	struct kthread_delayed_work read_work;
 	struct kthread_work write_work;
 	struct list_head queue;
 };
 
-#if IS_ENABLED(CONFIG_TTY)
+#if IS_ENABLED(CONFIG_ICE_GNSS)
 void ice_gnss_init(struct ice_pf *pf);
 void ice_gnss_exit(struct ice_pf *pf);
 bool ice_gnss_is_gps_present(struct ice_hw *hw);
@@ -70,5 +56,5 @@ static inline bool ice_gnss_is_gps_present(struct ice_hw *hw)
 {
 	return false;
 }
-#endif /* IS_ENABLED(CONFIG_TTY) */
+#endif /* IS_ENABLED(CONFIG_ICE_GNSS) */
 #endif /* _ICE_GNSS_H_ */
-- 
2.38.1

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