[PATCH net-next 0/3][pull request] 1GbE Intel Wired LAN Driver Updates 2021-08-27

[PATCH net-next 0/3][pull request] 1GbE Intel Wired LAN Driver Updates 2021-08-27

[Tony Nguyen]

Aravindhan Gunasekaran says:

This adds support for Credit-based shaper qdisc offload from
Traffic Control system. It enables traffic prioritization and
bandwidth reservation via the Credit-Based Shaper which is
implemented in hardware by i225 controller.

Patch 1/3 adds a default cycle-time for TSN mode to be configured.

Patch 2/3 helps to separate TSN mode programming on the fly and
during reset sequence. It also simplifies handling features flags
for various TSN modes supported by i225 in the driver.

Patch 3/3 adds support for IEEE802.1Qav(CBS) standard
implemented in i225 HW. Two sets of CBS HW shapers are present
in i225 and driver enables them in the two high priority queues.

The following are changes since commit 4baf0e0b329874ec5e85480f53851b5f05a7ae58:
  um: vector: adjust to coalesce API changes
and are available in the git repository at:
  git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue 1GbE

Aravindhan Gunasekaran (1):
  igc: Add support for CBS offloading

Vinicius Costa Gomes (2):
  igc: Use default cycle 'start' and 'end' values for queues
  igc: Simplify TSN flags handling

 drivers/net/ethernet/intel/igc/igc.h         |  11 ++
 drivers/net/ethernet/intel/igc/igc_defines.h |   8 +
 drivers/net/ethernet/intel/igc/igc_main.c    | 110 ++++++++++--
 drivers/net/ethernet/intel/igc/igc_regs.h    |   3 +
 drivers/net/ethernet/intel/igc/igc_tsn.c     | 174 +++++++++++++++----
 drivers/net/ethernet/intel/igc/igc_tsn.h     |   1 +
 6 files changed, 258 insertions(+), 49 deletions(-)

-- 
2.26.2

[PATCH net-next 1/3] igc: Use default cycle 'start' and 'end' values for queues

[Tony Nguyen]

From: Vinicius Costa Gomes <vinicius.gomes@intel.com>

Sets default values for each queue cycle start and cycle end.
This allows some simplification in the handling of these
configurations as most TSN features in i225 require a cycle
to be configured.

In i225, cycle start and end time is required to be programmed
for CBS to work properly.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Aravindhan Gunasekaran <aravindhan.gunasekaran@intel.com>
Signed-off-by: Mallikarjuna Chilakala <mallikarjuna.chilakala@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 37 +++++++++++++----------
 drivers/net/ethernet/intel/igc/igc_tsn.c  |  6 ----
 2 files changed, 21 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index c6c075a637ea..411d6caa27b5 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -5749,7 +5749,6 @@ static int igc_save_launchtime_params(struct igc_adapter *adapter, int queue,
 				      bool enable)
 {
 	struct igc_ring *ring;
-	int i;
 
 	if (queue < 0 || queue >= adapter->num_tx_queues)
 		return -EINVAL;
@@ -5757,17 +5756,6 @@ static int igc_save_launchtime_params(struct igc_adapter *adapter, int queue,
 	ring = adapter->tx_ring[queue];
 	ring->launchtime_enable = enable;
 
-	if (adapter->base_time)
-		return 0;
-
-	adapter->cycle_time = NSEC_PER_SEC;
-
-	for (i = 0; i < adapter->num_tx_queues; i++) {
-		ring = adapter->tx_ring[i];
-		ring->start_time = 0;
-		ring->end_time = NSEC_PER_SEC;
-	}
-
 	return 0;
 }
 
@@ -5840,16 +5828,31 @@ static int igc_tsn_enable_launchtime(struct igc_adapter *adapter,
 	return igc_tsn_offload_apply(adapter);
 }
 
+static int igc_tsn_clear_schedule(struct igc_adapter *adapter)
+{
+	int i;
+
+	adapter->base_time = 0;
+	adapter->cycle_time = NSEC_PER_SEC;
+
+	for (i = 0; i < adapter->num_tx_queues; i++) {
+		struct igc_ring *ring = adapter->tx_ring[i];
+
+		ring->start_time = 0;
+		ring->end_time = NSEC_PER_SEC;
+	}
+
+	return 0;
+}
+
 static int igc_save_qbv_schedule(struct igc_adapter *adapter,
 				 struct tc_taprio_qopt_offload *qopt)
 {
 	u32 start_time = 0, end_time = 0;
 	size_t n;
 
-	if (!qopt->enable) {
-		adapter->base_time = 0;
-		return 0;
-	}
+	if (!qopt->enable)
+		return igc_tsn_clear_schedule(adapter);
 
 	if (adapter->base_time)
 		return -EALREADY;
@@ -6339,6 +6342,8 @@ static int igc_probe(struct pci_dev *pdev,
 
 	igc_ptp_init(adapter);
 
+	igc_tsn_clear_schedule(adapter);
+
 	/* reset the hardware with the new settings */
 	igc_reset(adapter);
 
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index 4dbbb8a32ce9..5bcdf7583505 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -41,12 +41,6 @@ static int igc_tsn_disable_offload(struct igc_adapter *adapter)
 	wr32(IGC_TQAVCTRL, tqavctrl);
 
 	for (i = 0; i < adapter->num_tx_queues; i++) {
-		struct igc_ring *ring = adapter->tx_ring[i];
-
-		ring->start_time = 0;
-		ring->end_time = 0;
-		ring->launchtime_enable = false;
-
 		wr32(IGC_TXQCTL(i), 0);
 		wr32(IGC_STQT(i), 0);
 		wr32(IGC_ENDQT(i), NSEC_PER_SEC);
-- 
2.26.2

[PATCH net-next 2/3] igc: Simplify TSN flags handling

[Tony Nguyen]

From: Vinicius Costa Gomes <vinicius.gomes@intel.com>

Separates the procedure done during reset from applying a
configuration, knowing when the code is executing allow us to
separate the better what changes the hardware state from what
changes only the driver state.

Introduces a flag for bookkeeping the driver state of TSN
features. When Qav and frame-preemption is also implemented
this flag makes it easier to keep track on whether a TSN feature
driver state is enabled or not though controller state changes,
say, during a reset.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Aravindhan Gunasekaran <aravindhan.gunasekaran@intel.com>
Signed-off-by: Mallikarjuna Chilakala <mallikarjuna.chilakala@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc.h      |  2 +
 drivers/net/ethernet/intel/igc/igc_main.c |  2 +-
 drivers/net/ethernet/intel/igc/igc_tsn.c  | 65 ++++++++++++++---------
 drivers/net/ethernet/intel/igc/igc_tsn.h  |  1 +
 4 files changed, 43 insertions(+), 27 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index 2d17a6da63cf..b561beb1e623 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -291,6 +291,8 @@ extern char igc_driver_name[];
 #define IGC_FLAG_RX_LEGACY		BIT(16)
 #define IGC_FLAG_TSN_QBV_ENABLED	BIT(17)
 
+#define IGC_FLAG_TSN_ANY_ENABLED	IGC_FLAG_TSN_QBV_ENABLED
+
 #define IGC_FLAG_RSS_FIELD_IPV4_UDP	BIT(6)
 #define IGC_FLAG_RSS_FIELD_IPV6_UDP	BIT(7)
 
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 411d6caa27b5..2e5c9b5a57d1 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -120,7 +120,7 @@ void igc_reset(struct igc_adapter *adapter)
 	igc_ptp_reset(adapter);
 
 	/* Re-enable TSN offloading, where applicable. */
-	igc_tsn_offload_apply(adapter);
+	igc_tsn_reset(adapter);
 
 	igc_get_phy_info(hw);
 }
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index 5bcdf7583505..2935d57c593d 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -18,8 +18,21 @@ static bool is_any_launchtime(struct igc_adapter *adapter)
 	return false;
 }
 
+static unsigned int igc_tsn_new_flags(struct igc_adapter *adapter)
+{
+	unsigned int new_flags = adapter->flags & ~IGC_FLAG_TSN_ANY_ENABLED;
+
+	if (adapter->base_time)
+		new_flags |= IGC_FLAG_TSN_QBV_ENABLED;
+
+	if (is_any_launchtime(adapter))
+		new_flags |= IGC_FLAG_TSN_QBV_ENABLED;
+
+	return new_flags;
+}
+
 /* Returns the TSN specific registers to their default values after
- * TSN offloading is disabled.
+ * the adapter is reset.
  */
 static int igc_tsn_disable_offload(struct igc_adapter *adapter)
 {
@@ -27,11 +40,6 @@ static int igc_tsn_disable_offload(struct igc_adapter *adapter)
 	u32 tqavctrl;
 	int i;
 
-	if (!(adapter->flags & IGC_FLAG_TSN_QBV_ENABLED))
-		return 0;
-
-	adapter->cycle_time = 0;
-
 	wr32(IGC_TXPBS, I225_TXPBSIZE_DEFAULT);
 	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_DEFAULT);
 
@@ -62,9 +70,6 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 	ktime_t base_time, systim;
 	int i;
 
-	if (adapter->flags & IGC_FLAG_TSN_QBV_ENABLED)
-		return 0;
-
 	cycle = adapter->cycle_time;
 	base_time = adapter->base_time;
 
@@ -119,33 +124,41 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 	wr32(IGC_BASET_H, baset_h);
 	wr32(IGC_BASET_L, baset_l);
 
-	adapter->flags |= IGC_FLAG_TSN_QBV_ENABLED;
-
 	return 0;
 }
 
-int igc_tsn_offload_apply(struct igc_adapter *adapter)
+int igc_tsn_reset(struct igc_adapter *adapter)
 {
-	bool is_any_enabled = adapter->base_time || is_any_launchtime(adapter);
+	unsigned int new_flags;
+	int err = 0;
 
-	if (!(adapter->flags & IGC_FLAG_TSN_QBV_ENABLED) && !is_any_enabled)
-		return 0;
+	new_flags = igc_tsn_new_flags(adapter);
+
+	if (!(new_flags & IGC_FLAG_TSN_ANY_ENABLED))
+		return igc_tsn_disable_offload(adapter);
+
+	err = igc_tsn_enable_offload(adapter);
+	if (err < 0)
+		return err;
 
-	if (!is_any_enabled) {
-		int err = igc_tsn_disable_offload(adapter);
+	adapter->flags = new_flags;
 
-		if (err < 0)
-			return err;
+	return err;
+}
 
-		/* The BASET registers aren't cleared when writing
-		 * into them, force a reset if the interface is
-		 * running.
-		 */
-		if (netif_running(adapter->netdev))
-			schedule_work(&adapter->reset_task);
+int igc_tsn_offload_apply(struct igc_adapter *adapter)
+{
+	int err;
 
+	if (netif_running(adapter->netdev)) {
+		schedule_work(&adapter->reset_task);
 		return 0;
 	}
 
-	return igc_tsn_enable_offload(adapter);
+	err = igc_tsn_enable_offload(adapter);
+	if (err < 0)
+		return err;
+
+	adapter->flags = igc_tsn_new_flags(adapter);
+	return 0;
 }
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.h b/drivers/net/ethernet/intel/igc/igc_tsn.h
index f76bc86ddccd..1512307f5a52 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.h
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.h
@@ -5,5 +5,6 @@
 #define _IGC_TSN_H_
 
 int igc_tsn_offload_apply(struct igc_adapter *adapter);
+int igc_tsn_reset(struct igc_adapter *adapter);
 
 #endif /* _IGC_BASE_H */
-- 
2.26.2

[PATCH net-next 3/3] igc: Add support for CBS offloading

[Tony Nguyen]

From: Aravindhan Gunasekaran <aravindhan.gunasekaran@intel.com>

Implement support for Credit-based shaper(CBS) Qdisc hardware
offload mode in the driver. There are two sets of IEEE802.1Qav
(CBS) HW logic in i225 controller and this patch supports
enabling them in the top two priority TX queues.

Driver implemented as recommended by Foxville External
Architecture Specification v0.993. Idleslope and Hi-credit are
the CBS tunable parameters for i225 NIC, programmed in TQAVCC
and TQAVHC registers respectively.

In-order for IEEE802.1Qav (CBS) algorithm to work as intended
and provide BW reservation CBS should be enabled in highest
priority queue first. If we enable CBS on any of low priority
queues, the traffic in high priority queue does not allow low
priority queue to be selected for transmission and bandwidth
reservation is not guaranteed.

Signed-off-by: Aravindhan Gunasekaran <aravindhan.gunasekaran@intel.com>
Signed-off-by: Mallikarjuna Chilakala <mallikarjuna.chilakala@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc.h         |  11 +-
 drivers/net/ethernet/intel/igc/igc_defines.h |   8 ++
 drivers/net/ethernet/intel/igc/igc_main.c    |  71 +++++++++++++
 drivers/net/ethernet/intel/igc/igc_regs.h    |   3 +
 drivers/net/ethernet/intel/igc/igc_tsn.c     | 103 +++++++++++++++++++
 5 files changed, 195 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index b561beb1e623..3e386c38d016 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -98,6 +98,13 @@ struct igc_ring {
 	u32 start_time;
 	u32 end_time;
 
+	/* CBS parameters */
+	bool cbs_enable;                /* indicates if CBS is enabled */
+	s32 idleslope;                  /* idleSlope in kbps */
+	s32 sendslope;                  /* sendSlope in kbps */
+	s32 hicredit;                   /* hiCredit in bytes */
+	s32 locredit;                   /* loCredit in bytes */
+
 	/* everything past this point are written often */
 	u16 next_to_clean;
 	u16 next_to_use;
@@ -290,8 +297,10 @@ extern char igc_driver_name[];
 #define IGC_FLAG_VLAN_PROMISC		BIT(15)
 #define IGC_FLAG_RX_LEGACY		BIT(16)
 #define IGC_FLAG_TSN_QBV_ENABLED	BIT(17)
+#define IGC_FLAG_TSN_QAV_ENABLED	BIT(18)
 
-#define IGC_FLAG_TSN_ANY_ENABLED	IGC_FLAG_TSN_QBV_ENABLED
+#define IGC_FLAG_TSN_ANY_ENABLED \
+	(IGC_FLAG_TSN_QBV_ENABLED | IGC_FLAG_TSN_QAV_ENABLED)
 
 #define IGC_FLAG_RSS_FIELD_IPV4_UDP	BIT(6)
 #define IGC_FLAG_RSS_FIELD_IPV6_UDP	BIT(7)
diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h b/drivers/net/ethernet/intel/igc/igc_defines.h
index c40563350a5e..a4bbee748798 100644
--- a/drivers/net/ethernet/intel/igc/igc_defines.h
+++ b/drivers/net/ethernet/intel/igc/igc_defines.h
@@ -518,6 +518,14 @@
 #define IGC_TXQCTL_QUEUE_MODE_LAUNCHT	0x00000001
 #define IGC_TXQCTL_STRICT_CYCLE		0x00000002
 #define IGC_TXQCTL_STRICT_END		0x00000004
+#define IGC_TXQCTL_QAV_SEL_MASK		0x000000C0
+#define IGC_TXQCTL_QAV_SEL_CBS0		0x00000080
+#define IGC_TXQCTL_QAV_SEL_CBS1		0x000000C0
+
+#define IGC_TQAVCC_IDLESLOPE_MASK	0xFFFF
+#define IGC_TQAVCC_KEEP_CREDITS		BIT(30)
+
+#define IGC_MAX_SR_QUEUES		2
 
 /* Receive Checksum Control */
 #define IGC_RXCSUM_CRCOFL	0x00000800   /* CRC32 offload enable */
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 2e5c9b5a57d1..b877efae61df 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -5904,6 +5904,74 @@ static int igc_tsn_enable_qbv_scheduling(struct igc_adapter *adapter,
 	return igc_tsn_offload_apply(adapter);
 }
 
+static int igc_save_cbs_params(struct igc_adapter *adapter, int queue,
+			       bool enable, int idleslope, int sendslope,
+			       int hicredit, int locredit)
+{
+	bool cbs_status[IGC_MAX_SR_QUEUES] = { false };
+	struct net_device *netdev = adapter->netdev;
+	struct igc_ring *ring;
+	int i;
+
+	/* i225 has two sets of credit-based shaper logic.
+	 * Supporting it only on the top two priority queues
+	 */
+	if (queue < 0 || queue > 1)
+		return -EINVAL;
+
+	ring = adapter->tx_ring[queue];
+
+	for (i = 0; i < IGC_MAX_SR_QUEUES; i++)
+		if (adapter->tx_ring[i])
+			cbs_status[i] = adapter->tx_ring[i]->cbs_enable;
+
+	/* CBS should be enabled on the highest priority queue first in order
+	 * for the CBS algorithm to operate as intended.
+	 */
+	if (enable) {
+		if (queue == 1 && !cbs_status[0]) {
+			netdev_err(netdev,
+				   "Enabling CBS on queue1 before queue0\n");
+			return -EINVAL;
+		}
+	} else {
+		if (queue == 0 && cbs_status[1]) {
+			netdev_err(netdev,
+				   "Disabling CBS on queue0 before queue1\n");
+			return -EINVAL;
+		}
+	}
+
+	ring->cbs_enable = enable;
+	ring->idleslope = idleslope;
+	ring->sendslope = sendslope;
+	ring->hicredit = hicredit;
+	ring->locredit = locredit;
+
+	return 0;
+}
+
+static int igc_tsn_enable_cbs(struct igc_adapter *adapter,
+			      struct tc_cbs_qopt_offload *qopt)
+{
+	struct igc_hw *hw = &adapter->hw;
+	int err;
+
+	if (hw->mac.type != igc_i225)
+		return -EOPNOTSUPP;
+
+	if (qopt->queue < 0 || qopt->queue > 1)
+		return -EINVAL;
+
+	err = igc_save_cbs_params(adapter, qopt->queue, qopt->enable,
+				  qopt->idleslope, qopt->sendslope,
+				  qopt->hicredit, qopt->locredit);
+	if (err)
+		return err;
+
+	return igc_tsn_offload_apply(adapter);
+}
+
 static int igc_setup_tc(struct net_device *dev, enum tc_setup_type type,
 			void *type_data)
 {
@@ -5916,6 +5984,9 @@ static int igc_setup_tc(struct net_device *dev, enum tc_setup_type type,
 	case TC_SETUP_QDISC_ETF:
 		return igc_tsn_enable_launchtime(adapter, type_data);
 
+	case TC_SETUP_QDISC_CBS:
+		return igc_tsn_enable_cbs(adapter, type_data);
+
 	default:
 		return -EOPNOTSUPP;
 	}
diff --git a/drivers/net/ethernet/intel/igc/igc_regs.h b/drivers/net/ethernet/intel/igc/igc_regs.h
index dbba2eb2a247..e197a33d93a0 100644
--- a/drivers/net/ethernet/intel/igc/igc_regs.h
+++ b/drivers/net/ethernet/intel/igc/igc_regs.h
@@ -236,6 +236,9 @@
 #define IGC_ENDQT(_n)		(0x3334 + 0x4 * (_n))
 #define IGC_DTXMXPKTSZ		0x355C
 
+#define IGC_TQAVCC(_n)		(0x3004 + ((_n) * 0x40))
+#define IGC_TQAVHC(_n)		(0x300C + ((_n) * 0x40))
+
 /* System Time Registers */
 #define IGC_SYSTIML	0x0B600  /* System time register Low - RO */
 #define IGC_SYSTIMH	0x0B604  /* System time register High - RO */
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index 2935d57c593d..0fce22de2ab8 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -18,6 +18,20 @@ static bool is_any_launchtime(struct igc_adapter *adapter)
 	return false;
 }
 
+static bool is_cbs_enabled(struct igc_adapter *adapter)
+{
+	int i;
+
+	for (i = 0; i < adapter->num_tx_queues; i++) {
+		struct igc_ring *ring = adapter->tx_ring[i];
+
+		if (ring->cbs_enable)
+			return true;
+	}
+
+	return false;
+}
+
 static unsigned int igc_tsn_new_flags(struct igc_adapter *adapter)
 {
 	unsigned int new_flags = adapter->flags & ~IGC_FLAG_TSN_ANY_ENABLED;
@@ -28,6 +42,9 @@ static unsigned int igc_tsn_new_flags(struct igc_adapter *adapter)
 	if (is_any_launchtime(adapter))
 		new_flags |= IGC_FLAG_TSN_QBV_ENABLED;
 
+	if (is_cbs_enabled(adapter))
+		new_flags |= IGC_FLAG_TSN_QAV_ENABLED;
+
 	return new_flags;
 }
 
@@ -87,6 +104,8 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 	for (i = 0; i < adapter->num_tx_queues; i++) {
 		struct igc_ring *ring = adapter->tx_ring[i];
 		u32 txqctl = 0;
+		u16 cbs_value;
+		u32 tqavcc;
 
 		wr32(IGC_STQT(i), ring->start_time);
 		wr32(IGC_ENDQT(i), ring->end_time);
@@ -104,6 +123,90 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 		if (ring->launchtime_enable)
 			txqctl |= IGC_TXQCTL_QUEUE_MODE_LAUNCHT;
 
+		/* Skip configuring CBS for Q2 and Q3 */
+		if (i > 1)
+			goto skip_cbs;
+
+		if (ring->cbs_enable) {
+			if (i == 0)
+				txqctl |= IGC_TXQCTL_QAV_SEL_CBS0;
+			else
+				txqctl |= IGC_TXQCTL_QAV_SEL_CBS1;
+
+			/* According to i225 datasheet section 7.5.2.7, we
+			 * should set the 'idleSlope' field from TQAVCC
+			 * register following the equation:
+			 *
+			 * value = link-speed   0x7736 * BW * 0.2
+			 *         ---------- *  -----------------         (E1)
+			 *          100Mbps            2.5
+			 *
+			 * Note that 'link-speed' is in Mbps.
+			 *
+			 * 'BW' is the percentage bandwidth out of full
+			 * link speed which can be found with the
+			 * following equation. Note that idleSlope here
+			 * is the parameter from this function
+			 * which is in kbps.
+			 *
+			 *     BW =     idleSlope
+			 *          -----------------                      (E2)
+			 *          link-speed * 1000
+			 *
+			 * That said, we can come up with a generic
+			 * equation to calculate the value we should set
+			 * it TQAVCC register by replacing 'BW' in E1 by E2.
+			 * The resulting equation is:
+			 *
+			 * value = link-speed * 0x7736 * idleSlope * 0.2
+			 *         -------------------------------------   (E3)
+			 *             100 * 2.5 * link-speed * 1000
+			 *
+			 * 'link-speed' is present in both sides of the
+			 * fraction so it is canceled out. The final
+			 * equation is the following:
+			 *
+			 *     value = idleSlope * 61036
+			 *             -----------------                   (E4)
+			 *                  2500000
+			 *
+			 * NOTE: For i225, given the above, we can see
+			 *       that idleslope is represented in
+			 *       40.959433 kbps units by the value at
+			 *       the TQAVCC register (2.5Gbps / 61036),
+			 *       which reduces the granularity for
+			 *       idleslope increments.
+			 *
+			 * In i225 controller, the sendSlope and loCredit
+			 * parameters from CBS are not configurable
+			 * by software so we don't do any
+			 * 'controller configuration' in respect to
+			 * these parameters.
+			 */
+			cbs_value = DIV_ROUND_UP_ULL(ring->idleslope
+						     * 61036ULL, 2500000);
+
+			tqavcc = rd32(IGC_TQAVCC(i));
+			tqavcc &= ~IGC_TQAVCC_IDLESLOPE_MASK;
+			tqavcc |= cbs_value | IGC_TQAVCC_KEEP_CREDITS;
+			wr32(IGC_TQAVCC(i), tqavcc);
+
+			wr32(IGC_TQAVHC(i),
+			     0x80000000 + ring->hicredit * 0x7735);
+		} else {
+			/* Disable any CBS for the queue */
+			txqctl &= ~(IGC_TXQCTL_QAV_SEL_MASK);
+
+			/* Set idleSlope to zero. */
+			tqavcc = rd32(IGC_TQAVCC(i));
+			tqavcc &= ~(IGC_TQAVCC_IDLESLOPE_MASK |
+				    IGC_TQAVCC_KEEP_CREDITS);
+			wr32(IGC_TQAVCC(i), tqavcc);
+
+			/* Set hiCredit to zero. */
+			wr32(IGC_TQAVHC(i), 0);
+		}
+skip_cbs:
 		wr32(IGC_TXQCTL(i), txqctl);
 	}
 
-- 
2.26.2

Re: [PATCH net-next 0/3][pull request] 1GbE Intel Wired LAN Driver Updates 2021-08-27

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Fri, 27 Aug 2021 10:25:10 -0700 you wrote:
> Aravindhan Gunasekaran says:
> 
> This adds support for Credit-based shaper qdisc offload from
> Traffic Control system. It enables traffic prioritization and
> bandwidth reservation via the Credit-Based Shaper which is
> implemented in hardware by i225 controller.
> 
> [...]

Here is the summary with links:
  - [net-next,1/3] igc: Use default cycle 'start' and 'end' values for queues
    https://git.kernel.org/netdev/net-next/c/c814a2d2d48f
  - [net-next,2/3] igc: Simplify TSN flags handling
    https://git.kernel.org/netdev/net-next/c/61572d5f8f91
  - [net-next,3/3] igc: Add support for CBS offloading
    https://git.kernel.org/netdev/net-next/c/1ab011b0bf07

You are awesome, thank you!
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