ice: exit bypass mode once hardware finishes timestamp calibration

Once the E822 device has sent and received one packet, the hardware
computes the internal delay of the PHY using a process known as Vernier
calibration. This calibration calculates a more accurate offset for the
Tx and Rx timestamps. To make use of this offset, we need to exit the
bypass mode. This cannot be done until the PHY has completed offset
calibration, as indicated by the offset valid bits.

To handle this, introduce a kthread work item which will poll the offset
valid bits every few milliseconds seeing if it is safe to exit bypass
mode.

Once we have finished calibrating the offsets, we can program the total
Tx and Rx offset registers and turn off the bypass bit. This allows the
hardware to include the more precise vernier calibration offset, and
improves the timestamp precision.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_ptp.c

@@ -720,6 +720,192 @@ static void ice_ptp_reset_ts_memory_quad(struct ice_pf *pf, int quad)
 	ice_write_quad_reg_e822(hw, quad, Q_REG_TS_CTRL, ~(u32)Q_REG_TS_CTRL_M);
 }
 
+/**
+ * ice_ptp_check_tx_fifo - Check whether Tx FIFO is in an OK state
+ * @port: PTP port for which Tx FIFO is checked
+ */
+static int ice_ptp_check_tx_fifo(struct ice_ptp_port *port)
+{
+	int quad = port->port_num / ICE_PORTS_PER_QUAD;
+	int offs = port->port_num % ICE_PORTS_PER_QUAD;
+	struct ice_pf *pf;
+	struct ice_hw *hw;
+	u32 val, phy_sts;
+	int err;
+
+	pf = ptp_port_to_pf(port);
+	hw = &pf->hw;
+
+	if (port->tx_fifo_busy_cnt == FIFO_OK)
+		return 0;
+
+	/* need to read FIFO state */
+	if (offs == 0 || offs == 1)
+		err = ice_read_quad_reg_e822(hw, quad, Q_REG_FIFO01_STATUS,
+					     &val);
+	else
+		err = ice_read_quad_reg_e822(hw, quad, Q_REG_FIFO23_STATUS,
+					     &val);
+
+	if (err) {
+		dev_err(ice_pf_to_dev(pf), "PTP failed to check port %d Tx FIFO, err %d\n",
+			port->port_num, err);
+		return err;
+	}
+
+	if (offs & 0x1)
+		phy_sts = (val & Q_REG_FIFO13_M) >> Q_REG_FIFO13_S;
+	else
+		phy_sts = (val & Q_REG_FIFO02_M) >> Q_REG_FIFO02_S;
+
+	if (phy_sts & FIFO_EMPTY) {
+		port->tx_fifo_busy_cnt = FIFO_OK;
+		return 0;
+	}
+
+	port->tx_fifo_busy_cnt++;
+
+	dev_dbg(ice_pf_to_dev(pf), "Try %d, port %d FIFO not empty\n",
+		port->tx_fifo_busy_cnt, port->port_num);
+
+	if (port->tx_fifo_busy_cnt == ICE_PTP_FIFO_NUM_CHECKS) {
+		dev_dbg(ice_pf_to_dev(pf),
+			"Port %d Tx FIFO still not empty; resetting quad %d\n",
+			port->port_num, quad);
+		ice_ptp_reset_ts_memory_quad(pf, quad);
+		port->tx_fifo_busy_cnt = FIFO_OK;
+		return 0;
+	}
+
+	return -EAGAIN;
+}
+
+/**
+ * ice_ptp_check_tx_offset_valid - Check if the Tx PHY offset is valid
+ * @port: the PTP port to check
+ *
+ * Checks whether the Tx offset for the PHY associated with this port is
+ * valid. Returns 0 if the offset is valid, and a non-zero error code if it is
+ * not.
+ */
+static int ice_ptp_check_tx_offset_valid(struct ice_ptp_port *port)
+{
+	struct ice_pf *pf = ptp_port_to_pf(port);
+	struct device *dev = ice_pf_to_dev(pf);
+	struct ice_hw *hw = &pf->hw;
+	u32 val;
+	int err;
+
+	err = ice_ptp_check_tx_fifo(port);
+	if (err)
+		return err;
+
+	err = ice_read_phy_reg_e822(hw, port->port_num, P_REG_TX_OV_STATUS,
+				    &val);
+	if (err) {
+		dev_err(dev, "Failed to read TX_OV_STATUS for port %d, err %d\n",
+			port->port_num, err);
+		return -EAGAIN;
+	}
+
+	if (!(val & P_REG_TX_OV_STATUS_OV_M))
+		return -EAGAIN;
+
+	return 0;
+}
+
+/**
+ * ice_ptp_check_rx_offset_valid - Check if the Rx PHY offset is valid
+ * @port: the PTP port to check
+ *
+ * Checks whether the Rx offset for the PHY associated with this port is
+ * valid. Returns 0 if the offset is valid, and a non-zero error code if it is
+ * not.
+ */
+static int ice_ptp_check_rx_offset_valid(struct ice_ptp_port *port)
+{
+	struct ice_pf *pf = ptp_port_to_pf(port);
+	struct device *dev = ice_pf_to_dev(pf);
+	struct ice_hw *hw = &pf->hw;
+	int err;
+	u32 val;
+
+	err = ice_read_phy_reg_e822(hw, port->port_num, P_REG_RX_OV_STATUS,
+				    &val);
+	if (err) {
+		dev_err(dev, "Failed to read RX_OV_STATUS for port %d, err %d\n",
+			port->port_num, err);
+		return err;
+	}
+
+	if (!(val & P_REG_RX_OV_STATUS_OV_M))
+		return -EAGAIN;
+
+	return 0;
+}
+
+/**
+ * ice_ptp_check_offset_valid - Check port offset valid bit
+ * @port: Port for which offset valid bit is checked
+ *
+ * Returns 0 if both Tx and Rx offset are valid, and -EAGAIN if one of the
+ * offset is not ready.
+ */
+static int ice_ptp_check_offset_valid(struct ice_ptp_port *port)
+{
+	int tx_err, rx_err;
+
+	/* always check both Tx and Rx offset validity */
+	tx_err = ice_ptp_check_tx_offset_valid(port);
+	rx_err = ice_ptp_check_rx_offset_valid(port);
+
+	if (tx_err || rx_err)
+		return -EAGAIN;
+
+	return 0;
+}
+
+/**
+ * ice_ptp_wait_for_offset_valid - Check for valid Tx and Rx offsets
+ * @work: Pointer to the kthread_work structure for this task
+ *
+ * Check whether both the Tx and Rx offsets are valid for enabling the vernier
+ * calibration.
+ *
+ * Once we have valid offsets from hardware, update the total Tx and Rx
+ * offsets, and exit bypass mode. This enables more precise timestamps using
+ * the extra data measured during the vernier calibration process.
+ */
+static void ice_ptp_wait_for_offset_valid(struct kthread_work *work)
+{
+	struct ice_ptp_port *port;
+	int err;
+	struct device *dev;
+	struct ice_pf *pf;
+	struct ice_hw *hw;
+
+	port = container_of(work, struct ice_ptp_port, ov_work.work);
+	pf = ptp_port_to_pf(port);
+	hw = &pf->hw;
+	dev = ice_pf_to_dev(pf);
+
+	if (ice_ptp_check_offset_valid(port)) {
+		/* Offsets not ready yet, try again later */
+		kthread_queue_delayed_work(pf->ptp.kworker,
+					   &port->ov_work,
+					   msecs_to_jiffies(100));
+		return;
+	}
+
+	/* Offsets are valid, so it is safe to exit bypass mode */
+	err = ice_phy_exit_bypass_e822(hw, port->port_num);
+	if (err) {
+		dev_warn(dev, "Failed to exit bypass mode for PHY port %u, err %d\n",
+			 port->port_num, err);
+		return;
+	}
+}
+
 /**
  * ice_ptp_port_phy_stop - Stop timestamping for a PHY port
  * @ptp_port: PTP port to stop
@@ -737,6 +923,8 @@ ice_ptp_port_phy_stop(struct ice_ptp_port *ptp_port)
 
 	mutex_lock(&ptp_port->ps_lock);
 
+	kthread_cancel_delayed_work_sync(&ptp_port->ov_work);
+
 	err = ice_stop_phy_timer_e822(hw, port, true);
 	if (err)
 		dev_err(ice_pf_to_dev(pf), "PTP failed to set PHY port %d down, err %d\n",
@@ -771,8 +959,11 @@ ice_ptp_port_phy_restart(struct ice_ptp_port *ptp_port)
 
 	mutex_lock(&ptp_port->ps_lock);
 
+	kthread_cancel_delayed_work_sync(&ptp_port->ov_work);
+
 	/* temporarily disable Tx timestamps while calibrating PHY offset */
 	ptp_port->tx.calibrating = true;
+	ptp_port->tx_fifo_busy_cnt = 0;
 
 	/* Start the PHY timer in bypass mode */
 	err = ice_start_phy_timer_e822(hw, port, true);
@@ -782,6 +973,8 @@ ice_ptp_port_phy_restart(struct ice_ptp_port *ptp_port)
 	/* Enable Tx timestamps right away */
 	ptp_port->tx.calibrating = false;
 
+	kthread_queue_delayed_work(pf->ptp.kworker, &ptp_port->ov_work, 0);
+
 out_unlock:
 	if (err)
 		dev_err(ice_pf_to_dev(pf), "PTP failed to set PHY port %d up, err %d\n",
@@ -2083,11 +2276,14 @@ void ice_ptp_reset(struct ice_pf *pf)
 
 pfr:
 	/* Init Tx structures */
-	if (ice_is_e810(&pf->hw))
+	if (ice_is_e810(&pf->hw)) {
 		err = ice_ptp_init_tx_e810(pf, &ptp->port.tx);
-	else
+	} else {
+		kthread_init_delayed_work(&ptp->port.ov_work,
+					  ice_ptp_wait_for_offset_valid);
 		err = ice_ptp_init_tx_e822(pf, &ptp->port.tx,
 					   ptp->port.port_num);
+	}
 	if (err)
 		goto err;
 
@@ -2246,6 +2442,8 @@ static int ice_ptp_init_port(struct ice_pf *pf, struct ice_ptp_port *ptp_port)
 	if (ice_is_e810(&pf->hw))
 		return ice_ptp_init_tx_e810(pf, &ptp_port->tx);
 
+	kthread_init_delayed_work(&ptp_port->ov_work,
+				  ice_ptp_wait_for_offset_valid);
 	return ice_ptp_init_tx_e822(pf, &ptp_port->tx, ptp_port->port_num);
 }
 

drivers/net/ethernet/intel/ice/ice_ptp.h

@@ -109,14 +109,18 @@ struct ice_ptp_tx {
  * and determine when the port's PHY offset is valid.
  *
  * @tx: Tx timestamp tracking for this port
+ * @ov_work: delayed work task for tracking when PHY offset is valid
  * @ps_lock: mutex used to protect the overall PTP PHY start procedure
  * @link_up: indicates whether the link is up
+ * @tx_fifo_busy_cnt: number of times the Tx FIFO was busy
  * @port_num: the port number this structure represents
  */
 struct ice_ptp_port {
 	struct ice_ptp_tx tx;
+	struct kthread_delayed_work ov_work;
 	struct mutex ps_lock; /* protects overall PTP PHY start procedure */
 	bool link_up;
+	u8 tx_fifo_busy_cnt;
 	u8 port_num;
 };
 

drivers/net/ethernet/intel/ice/ice_ptp_hw.h

@@ -185,6 +185,7 @@ static inline u64 ice_e822_pps_delay(enum ice_time_ref_freq time_ref)
 /* E822 Vernier calibration functions */
 int ice_stop_phy_timer_e822(struct ice_hw *hw, u8 port, bool soft_reset);
 int ice_start_phy_timer_e822(struct ice_hw *hw, u8 port, bool bypass);
+int ice_phy_exit_bypass_e822(struct ice_hw *hw, u8 port);
 
 /* E810 family functions */
 int ice_ptp_init_phy_e810(struct ice_hw *hw);