ice: add TTY for GNSS module for E810T device

Add a new ice_gnss.c file for holding the basic GNSS module functions.
If the device supports GNSS module, call the new ice_gnss_init and
ice_gnss_release functions where appropriate.

Implement basic functionality for reading the data from GNSS module
using TTY device.

Add I2C read AQ command. It is now required for controlling the external
physical connectors via external I2C port expander on E810-T adapters.

Future changes will introduce write functionality.

Signed-off-by: Karol Kolacinski <karol.kolacinski@intel.com>
Signed-off-by: Sudhansu Sekhar Mishra <sudhansu.mishra@intel.com>
Tested-by: Sunitha Mekala <sunithax.d.mekala@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 376 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/ice/ice_gnss.c b/drivers/net/ethernet/intel/ice/ice_gnss.c
new file mode 100644
index 000000000000..755e1580f368
--- /dev/null
+++ b/drivers/net/ethernet/intel/ice/ice_gnss.c
@@ -0,0 +1,376 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2018-2021, Intel Corporation. */
+
+#include "ice.h"
+#include "ice_lib.h"
+#include <linux/tty_driver.h>
+
+/**
+ * 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.
+ */
+static void ice_gnss_read(struct kthread_work *work)
+{
+	struct gnss_serial *gnss = container_of(work, struct gnss_serial,
+						read_work.work);
+	struct ice_aqc_link_topo_addr link_topo;
+	u8 i2c_params, bytes_read;
+	struct tty_port *port;
+	struct ice_pf *pf;
+	struct ice_hw *hw;
+	__be16 data_len_b;
+	char *buf = NULL;
+	u16 i, data_len;
+	int err = 0;
+
+	pf = gnss->back;
+	if (!pf || !gnss->tty || !gnss->tty->port) {
+		err = -EFAULT;
+		goto exit;
+	}
+
+	hw = &pf->hw;
+	port = gnss->tty->port;
+
+	buf = (char *)get_zeroed_page(GFP_KERNEL);
+	if (!buf) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	memset(&link_topo, 0, sizeof(struct ice_aqc_link_topo_addr));
+	link_topo.topo_params.index = ICE_E810T_GNSS_I2C_BUS;
+	link_topo.topo_params.node_type_ctx |=
+		FIELD_PREP(ICE_AQC_LINK_TOPO_NODE_CTX_M,
+			   ICE_AQC_LINK_TOPO_NODE_CTX_OVERRIDE);
+
+	i2c_params = ICE_GNSS_UBX_DATA_LEN_WIDTH |
+		     ICE_AQC_I2C_USE_REPEATED_START;
+
+	/* Read data length in a loop, when it's not 0 the data is ready */
+	for (i = 0; i < ICE_MAX_UBX_READ_TRIES; i++) {
+		err = ice_aq_read_i2c(hw, link_topo, ICE_GNSS_UBX_I2C_BUS_ADDR,
+				      cpu_to_le16(ICE_GNSS_UBX_DATA_LEN_H),
+				      i2c_params, (u8 *)&data_len_b, NULL);
+		if (err)
+			goto exit_buf;
+
+		data_len = be16_to_cpu(data_len_b);
+		if (data_len != 0 && data_len != U16_MAX)
+			break;
+
+		mdelay(10);
+	}
+
+	data_len = min(data_len, (u16)PAGE_SIZE);
+	data_len = tty_buffer_request_room(port, data_len);
+	if (!data_len) {
+		err = -ENOMEM;
+		goto exit_buf;
+	}
+
+	/* Read received data */
+	for (i = 0; i < data_len; i += bytes_read) {
+		u16 bytes_left = data_len - i;
+
+		bytes_read = bytes_left < ICE_MAX_I2C_DATA_SIZE ? bytes_left :
+					  ICE_MAX_I2C_DATA_SIZE;
+
+		err = ice_aq_read_i2c(hw, link_topo, ICE_GNSS_UBX_I2C_BUS_ADDR,
+				      cpu_to_le16(ICE_GNSS_UBX_EMPTY_DATA),
+				      bytes_read, &buf[i], NULL);
+		if (err)
+			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);
+
+exit_buf:
+	free_page((unsigned long)buf);
+	kthread_queue_delayed_work(gnss->kworker, &gnss->read_work,
+				   ICE_GNSS_TIMER_DELAY_TIME);
+exit:
+	if (err)
+		dev_dbg(ice_pf_to_dev(pf), "GNSS failed to read err=%d\n", err);
+}
+
+/**
+ * ice_gnss_struct_init - Initialize GNSS structure for the TTY
+ * @pf: Board private structure
+ */
+static struct gnss_serial *ice_gnss_struct_init(struct ice_pf *pf)
+{
+	struct device *dev = ice_pf_to_dev(pf);
+	struct kthread_worker *kworker;
+	struct gnss_serial *gnss;
+
+	gnss = kzalloc(sizeof(*gnss), GFP_KERNEL);
+	if (!gnss)
+		return NULL;
+
+	mutex_init(&gnss->gnss_mutex);
+	gnss->open_count = 0;
+	gnss->back = pf;
+	pf->gnss_serial = gnss;
+
+	kthread_init_delayed_work(&gnss->read_work, ice_gnss_read);
+	/* Allocate a kworker for handling work required for the GNSS TTY
+	 * writes.
+	 */
+	kworker = kthread_create_worker(0, "ice-gnss-%s", dev_name(dev));
+	if (!kworker) {
+		kfree(gnss);
+		return NULL;
+	}
+
+	gnss->kworker = kworker;
+
+	return gnss;
+}
+
+/**
+ * ice_gnss_tty_open - Initialize GNSS structures on TTY device open
+ * @tty: pointer to the tty_struct
+ * @filp: pointer to the file
+ *
+ * This routine is mandatory. If this routine is not filled in, the attempted
+ * open will fail with ENODEV.
+ */
+static int ice_gnss_tty_open(struct tty_struct *tty, struct file *filp)
+{
+	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;
+	if (!gnss) {
+		/* Initialize GNSS struct on the first device open */
+		gnss = ice_gnss_struct_init(pf);
+		if (!gnss)
+			return -ENOMEM;
+	}
+
+	mutex_lock(&gnss->gnss_mutex);
+
+	/* 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
+ */
+static void ice_gnss_tty_close(struct tty_struct *tty, struct file *filp)
+{
+	struct gnss_serial *gnss = tty->driver_data;
+	struct ice_pf *pf;
+
+	if (!gnss)
+		return;
+
+	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->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);
+}
+
+/**
+ * ice_gnss_tty_write - Dummy TTY write function to avoid kernel panic
+ * @tty: pointer to the tty_struct
+ * @buf: pointer to the user data
+ * @cnt: the number of characters that was able to be sent to the hardware (or
+ *       queued to be sent at a later time)
+ */
+static int
+ice_gnss_tty_write(struct tty_struct *tty, const unsigned char *buf, int cnt)
+{
+	return 0;
+}
+
+/**
+ * ice_gnss_tty_write_room - Dummy TTY write_room function to avoid kernel panic
+ * @tty: pointer to the tty_struct
+ */
+static unsigned int ice_gnss_tty_write_room(struct tty_struct *tty)
+{
+	return 0;
+}
+
+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
+ * @pf: Board private structure
+ */
+static struct tty_driver *ice_gnss_create_tty_driver(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;
+	int err;
+
+	tty_driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW);
+	if (!tty_driver) {
+		dev_err(ice_pf_to_dev(pf), "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;
+	}
+
+	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);
+
+	pf->gnss_serial = NULL;
+
+	tty_port_init(&pf->gnss_tty_port);
+	tty_port_link_device(&pf->gnss_tty_port, tty_driver, 0);
+
+	err = tty_register_driver(tty_driver);
+	if (err) {
+		dev_err(ice_pf_to_dev(pf), "Failed to register TTY driver err=%d\n",
+			err);
+
+		tty_port_destroy(&pf->gnss_tty_port);
+		kfree(ttydrv_name);
+		tty_driver_kref_put(pf->ice_gnss_tty_driver);
+
+		return NULL;
+	}
+
+	return tty_driver;
+}
+
+/**
+ * ice_gnss_init - Initialize GNSS TTY support
+ * @pf: Board private structure
+ */
+void ice_gnss_init(struct ice_pf *pf)
+{
+	struct tty_driver *tty_driver;
+
+	tty_driver = ice_gnss_create_tty_driver(pf);
+	if (!tty_driver)
+		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");
+}
+
+/**
+ * ice_gnss_exit - Disable GNSS TTY support
+ * @pf: Board private structure
+ */
+void ice_gnss_exit(struct ice_pf *pf)
+{
+	if (!test_bit(ICE_FLAG_GNSS, pf->flags) || !pf->ice_gnss_tty_driver)
+		return;
+
+	tty_port_destroy(&pf->gnss_tty_port);
+
+	if (pf->gnss_serial) {
+		struct gnss_serial *gnss = pf->gnss_serial;
+
+		kthread_cancel_delayed_work_sync(&gnss->read_work);
+		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;
+}
+
+/**
+ * ice_gnss_is_gps_present - Check if GPS HW is present
+ * @hw: pointer to HW struct
+ */
+bool ice_gnss_is_gps_present(struct ice_hw *hw)
+{
+	if (!hw->func_caps.ts_func_info.src_tmr_owned)
+		return false;
+
+#if IS_ENABLED(CONFIG_PTP_1588_CLOCK)
+	if (ice_is_e810t(hw)) {
+		int err;
+		u8 data;
+
+		err = ice_read_pca9575_reg_e810t(hw, ICE_PCA9575_P0_IN, &data);
+		if (err || !!(data & ICE_E810T_P0_GNSS_PRSNT_N))
+			return false;
+	} else {
+		return false;
+	}
+#else
+	if (!ice_is_e810t(hw))
+		return false;
+#endif /* IS_ENABLED(CONFIG_PTP_1588_CLOCK) */
+
+	return true;
+}