ice: Add low latency Tx timestamp read

E810 products can support low latency Tx timestamp register read.
This requires usage of threaded IRQ instead of kthread to reduce the
kthread start latency (spikes up to 20 ms).
Add a check for the device capability and use the new method if
supported.

Signed-off-by: Karol Kolacinski <karol.kolacinski@intel.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://lore.kernel.org/r/20220916201728.241510-1-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 87 insertions, 11 deletions

diff --git a/drivers/net/ethernet/intel/ice/ice_ptp_hw.c b/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
index 6dff97d53d81..772b1f566d6e 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
+++ b/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (C) 2021, Intel Corporation. */
 
+#include <linux/delay.h>
 #include "ice_common.h"
 #include "ice_ptp_hw.h"
 #include "ice_ptp_consts.h"
@@ -2587,38 +2588,113 @@ static int ice_write_phy_reg_e810(struct ice_hw *hw, u32 addr, u32 val)
 }
 
 /**
- * ice_read_phy_tstamp_e810 - Read a PHY timestamp out of the external PHY
+ * ice_read_phy_tstamp_ll_e810 - Read a PHY timestamp registers through the FW
+ * @hw: pointer to the HW struct
+ * @idx: the timestamp index to read
+ * @hi: 8 bit timestamp high value
+ * @lo: 32 bit timestamp low value
+ *
+ * Read a 8bit timestamp high value and 32 bit timestamp low value out of the
+ * timestamp block of the external PHY on the E810 device using the low latency
+ * timestamp read.
+ */
+static int
+ice_read_phy_tstamp_ll_e810(struct ice_hw *hw, u8 idx, u8 *hi, u32 *lo)
+{
+	u32 val;
+	u8 i;
+
+	/* Write TS index to read to the PF register so the FW can read it */
+	val = FIELD_PREP(TS_LL_READ_TS_IDX, idx) | TS_LL_READ_TS;
+	wr32(hw, PF_SB_ATQBAL, val);
+
+	/* Read the register repeatedly until the FW provides us the TS */
+	for (i = TS_LL_READ_RETRIES; i > 0; i--) {
+		val = rd32(hw, PF_SB_ATQBAL);
+
+		/* When the bit is cleared, the TS is ready in the register */
+		if (!(FIELD_GET(TS_LL_READ_TS, val))) {
+			/* High 8 bit value of the TS is on the bits 16:23 */
+			*hi = FIELD_GET(TS_LL_READ_TS_HIGH, val);
+
+			/* Read the low 32 bit value and set the TS valid bit */
+			*lo = rd32(hw, PF_SB_ATQBAH) | TS_VALID;
+			return 0;
+		}
+
+		udelay(10);
+	}
+
+	/* FW failed to provide the TS in time */
+	ice_debug(hw, ICE_DBG_PTP, "Failed to read PTP timestamp using low latency read\n");
+	return -EINVAL;
+}
+
+/**
+ * ice_read_phy_tstamp_sbq_e810 - Read a PHY timestamp registers through the sbq
  * @hw: pointer to the HW struct
  * @lport: the lport to read from
  * @idx: the timestamp index to read
- * @tstamp: on return, the 40bit timestamp value
+ * @hi: 8 bit timestamp high value
+ * @lo: 32 bit timestamp low value
  *
- * Read a 40bit timestamp value out of the timestamp block of the external PHY
- * on the E810 device.
+ * Read a 8bit timestamp high value and 32 bit timestamp low value out of the
+ * timestamp block of the external PHY on the E810 device using sideband queue.
  */
 static int
-ice_read_phy_tstamp_e810(struct ice_hw *hw, u8 lport, u8 idx, u64 *tstamp)
+ice_read_phy_tstamp_sbq_e810(struct ice_hw *hw, u8 lport, u8 idx, u8 *hi,
+			     u32 *lo)
 {
-	u32 lo_addr, hi_addr, lo, hi;
+	u32 hi_addr = TS_EXT(HIGH_TX_MEMORY_BANK_START, lport, idx);
+	u32 lo_addr = TS_EXT(LOW_TX_MEMORY_BANK_START, lport, idx);
+	u32 lo_val, hi_val;
 	int err;
 
-	lo_addr = TS_EXT(LOW_TX_MEMORY_BANK_START, lport, idx);
-	hi_addr = TS_EXT(HIGH_TX_MEMORY_BANK_START, lport, idx);
-
-	err = ice_read_phy_reg_e810(hw, lo_addr, &lo);
+	err = ice_read_phy_reg_e810(hw, lo_addr, &lo_val);
 	if (err) {
 		ice_debug(hw, ICE_DBG_PTP, "Failed to read low PTP timestamp register, err %d\n",
 			  err);
 		return err;
 	}
 
-	err = ice_read_phy_reg_e810(hw, hi_addr, &hi);
+	err = ice_read_phy_reg_e810(hw, hi_addr, &hi_val);
 	if (err) {
 		ice_debug(hw, ICE_DBG_PTP, "Failed to read high PTP timestamp register, err %d\n",
 			  err);
 		return err;
 	}
 
+	*lo = lo_val;
+	*hi = (u8)hi_val;
+
+	return 0;
+}
+
+/**
+ * ice_read_phy_tstamp_e810 - Read a PHY timestamp out of the external PHY
+ * @hw: pointer to the HW struct
+ * @lport: the lport to read from
+ * @idx: the timestamp index to read
+ * @tstamp: on return, the 40bit timestamp value
+ *
+ * Read a 40bit timestamp value out of the timestamp block of the external PHY
+ * on the E810 device.
+ */
+static int
+ice_read_phy_tstamp_e810(struct ice_hw *hw, u8 lport, u8 idx, u64 *tstamp)
+{
+	u32 lo = 0;
+	u8 hi = 0;
+	int err;
+
+	if (hw->dev_caps.ts_dev_info.ts_ll_read)
+		err = ice_read_phy_tstamp_ll_e810(hw, idx, &hi, &lo);
+	else
+		err = ice_read_phy_tstamp_sbq_e810(hw, lport, idx, &hi, &lo);
+
+	if (err)
+		return err;
+
 	/* For E810 devices, the timestamp is reported with the lower 32 bits
 	 * in the low register, and the upper 8 bits in the high register.
 	 */