[PATCH] [v2] i40e: avoid 64-bit division where possible

[Arnd Bergmann <arnd@arndb.de>]

The new bandwidth calculation caused a link error on 32-bit
architectures, like

ERROR: "__aeabi_uldivmod" [drivers/net/ethernet/intel/i40e/i40e.ko] undefined!

The problem is the max_tx_rate calculation that uses 64-bit integers.
This is not really necessary since the numbers are in MBit/s so
they won't be higher than 40000 for the highest support rate, and
are guaranteed to not exceed 2^32 in future generations either.

Another patch from Alan Brady fixed the link error by adding
many calls to do_div(), which makes the code less efficent and
less readable than necessary.

This changes the representation to 'u32' when dealing with MBit/s
and uses div_u64() to convert from u64 numbers in byte/s, reverting
parts of Alan's earlier fix that have become obsolete now.

Fixes: 2027d4deacb1 ("i40e: Add support setting TC max bandwidth rates")
Fixes: 73983b5ae011 ("i40e: fix u64 division usage")
Cc: Alan Brady <alan.brady@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/intel/i40e/i40e.h      |  4 +-
 drivers/net/ethernet/intel/i40e/i40e_main.c | 70 +++++++++++------------------
 2 files changed, 27 insertions(+), 47 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index c3f13120f3ce..c7aa0c982273 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -407,7 +407,7 @@ struct i40e_channel {
 	u8 enabled_tc;
 	struct i40e_aqc_vsi_properties_data info;
 
-	u64 max_tx_rate;
+	u32 max_tx_rate; /* in Mbits/s */
 
 	/* track this channel belongs to which VSI */
 	struct i40e_vsi *parent_vsi;
@@ -1101,5 +1101,5 @@ static inline bool i40e_enabled_xdp_vsi(struct i40e_vsi *vsi)
 }
 
 int i40e_create_queue_channel(struct i40e_vsi *vsi, struct i40e_channel *ch);
-int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u64 max_tx_rate);
+int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u32 max_tx_rate);
 #endif /* _I40E_H_ */
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 3ceda140170d..57682cc78508 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -5448,17 +5448,16 @@ int i40e_get_link_speed(struct i40e_vsi *vsi)
  *
  * Helper function to set BW limit for a given VSI
  **/
-int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u64 max_tx_rate)
+int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u32 max_tx_rate)
 {
 	struct i40e_pf *pf = vsi->back;
-	u64 credits = 0;
 	int speed = 0;
 	int ret = 0;
 
 	speed = i40e_get_link_speed(vsi);
 	if (max_tx_rate > speed) {
 		dev_err(&pf->pdev->dev,
-			"Invalid max tx rate %llu specified for VSI seid %d.",
+			"Invalid max tx rate %u specified for VSI seid %d.",
 			max_tx_rate, seid);
 		return -EINVAL;
 	}
@@ -5469,13 +5468,12 @@ int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u64 max_tx_rate)
 	}
 
 	/* Tx rate credits are in values of 50Mbps, 0 is disabled */
-	credits = max_tx_rate;
-	do_div(credits, I40E_BW_CREDIT_DIVISOR);
-	ret = i40e_aq_config_vsi_bw_limit(&pf->hw, seid, credits,
+	ret = i40e_aq_config_vsi_bw_limit(&pf->hw, seid,
+					  max_tx_rate / I40E_BW_CREDIT_DIVISOR,
 					  I40E_MAX_BW_INACTIVE_ACCUM, NULL);
 	if (ret)
 		dev_err(&pf->pdev->dev,
-			"Failed set tx rate (%llu Mbps) for vsi->seid %u, err %s aq_err %s\n",
+			"Failed set tx rate (%u Mbps) for vsi->seid %u, err %s aq_err %s\n",
 			max_tx_rate, seid, i40e_stat_str(&pf->hw, ret),
 			i40e_aq_str(&pf->hw, pf->hw.aq.asq_last_status));
 	return ret;
@@ -6158,17 +6156,13 @@ int i40e_create_queue_channel(struct i40e_vsi *vsi,
 
 	/* configure VSI for BW limit */
 	if (ch->max_tx_rate) {
-		u64 credits = ch->max_tx_rate;
-
 		if (i40e_set_bw_limit(vsi, ch->seid, ch->max_tx_rate))
 			return -EINVAL;
 
-		do_div(credits, I40E_BW_CREDIT_DIVISOR);
 		dev_dbg(&pf->pdev->dev,
-			"Set tx rate of %llu Mbps (count of 50Mbps %llu) for vsi->seid %u\n",
+			"Set tx rate of %u Mbps (count of 50Mbps %u) for vsi->seid %u\n",
 			ch->max_tx_rate,
-			credits,
-			ch->seid);
+			ch->max_tx_rate / I40E_BW_CREDIT_DIVISOR, ch->seid);
 	}
 
 	/* in case of VF, this will be main SRIOV VSI */
@@ -6189,7 +6183,6 @@ int i40e_create_queue_channel(struct i40e_vsi *vsi,
 static int i40e_configure_queue_channels(struct i40e_vsi *vsi)
 {
 	struct i40e_channel *ch;
-	u64 max_rate = 0;
 	int ret = 0, i;
 
 	/* Create app vsi with the TCs. Main VSI with TC0 is already set up */
@@ -6211,9 +6204,8 @@ static int i40e_configure_queue_channels(struct i40e_vsi *vsi)
 			/* Bandwidth limit through tc interface is in bytes/s,
 			 * change to Mbit/s
 			 */
-			max_rate = vsi->mqprio_qopt.max_rate[i];
-			do_div(max_rate, I40E_BW_MBPS_DIVISOR);
-			ch->max_tx_rate = max_rate;
+			ch->max_tx_rate = div_u64(vsi->mqprio_qopt.max_rate[i],
+						  I40E_BW_CREDIT_DIVISOR);
 
 			list_add_tail(&ch->list, &vsi->ch_list);
 
@@ -6643,7 +6635,6 @@ static int i40e_validate_mqprio_qopt(struct i40e_vsi *vsi,
 				     struct tc_mqprio_qopt_offload *mqprio_qopt)
 {
 	u64 sum_max_rate = 0;
-	u64 max_rate = 0;
 	int i;
 
 	if (mqprio_qopt->qopt.offset[0] != 0 ||
@@ -6658,9 +6649,8 @@ static int i40e_validate_mqprio_qopt(struct i40e_vsi *vsi,
 				"Invalid min tx rate (greater than 0) specified\n");
 			return -EINVAL;
 		}
-		max_rate = mqprio_qopt->max_rate[i];
-		do_div(max_rate, I40E_BW_MBPS_DIVISOR);
-		sum_max_rate += max_rate;
+		sum_max_rate += div_u64(mqprio_qopt->max_rate[i],
+					I40E_BW_CREDIT_DIVISOR);
 
 		if (i >= mqprio_qopt->qopt.num_tc - 1)
 			break;
@@ -6804,18 +6794,14 @@ static int i40e_setup_tc(struct net_device *netdev, void *type_data)
 
 	if (pf->flags & I40E_FLAG_TC_MQPRIO) {
 		if (vsi->mqprio_qopt.max_rate[0]) {
-			u64 max_tx_rate = vsi->mqprio_qopt.max_rate[0];
-
-			do_div(max_tx_rate, I40E_BW_MBPS_DIVISOR);
+			u32 max_tx_rate = div_u64(vsi->mqprio_qopt.max_rate[0],
+						  I40E_BW_CREDIT_DIVISOR);
 			ret = i40e_set_bw_limit(vsi, vsi->seid, max_tx_rate);
 			if (!ret) {
-				u64 credits = max_tx_rate;
-
-				do_div(credits, I40E_BW_CREDIT_DIVISOR);
 				dev_dbg(&vsi->back->pdev->dev,
-					"Set tx rate of %llu Mbps (count of 50Mbps %llu) for vsi->seid %u\n",
+					"Set tx rate of %u Mbps (count of 50Mbps %u) for vsi->seid %u\n",
 					max_tx_rate,
-					credits,
+					max_tx_rate / I40E_BW_CREDIT_DIVISOR,
 					vsi->seid);
 			} else {
 				need_reset = true;
@@ -9024,15 +9010,12 @@ static int i40e_rebuild_channels(struct i40e_vsi *vsi)
 			return ret;
 		}
 		if (ch->max_tx_rate) {
-			u64 credits = ch->max_tx_rate;
-
 			if (i40e_set_bw_limit(vsi, ch->seid,
 					      ch->max_tx_rate))
 				return -EINVAL;
 
-			do_div(credits, I40E_BW_CREDIT_DIVISOR);
 			dev_dbg(&vsi->back->pdev->dev,
-				"Set tx rate of %llu Mbps (count of 50Mbps %llu) for vsi->seid %u\n",
+				"Set tx rate of %u Mbps (count of 50Mbps %u) for vsi->seid %u\n",
 				ch->max_tx_rate,
 				ch->max_tx_rate / I40E_BW_CREDIT_DIVISOR,
 				ch->seid);
@@ -9314,21 +9297,18 @@ static void i40e_rebuild(struct i40e_pf *pf, bool reinit, bool lock_acquired)
 	}
 
 	if (vsi->mqprio_qopt.max_rate[0]) {
-		u64 max_tx_rate = vsi->mqprio_qopt.max_rate[0];
-		u64 credits = 0;
+		u32 max_tx_rate = div_u64(vsi->mqprio_qopt.max_rate[0],
+					  I40E_BW_CREDIT_DIVISOR);
 
-		do_div(max_tx_rate, I40E_BW_MBPS_DIVISOR);
 		ret = i40e_set_bw_limit(vsi, vsi->seid, max_tx_rate);
-		if (ret)
+		if (!ret)
+			dev_dbg(&vsi->back->pdev->dev,
+				"Set tx rate of %u Mbps (count of 50Mbps %u) for vsi->seid %u\n",
+				max_tx_rate,
+				max_tx_rate / I40E_BW_CREDIT_DIVISOR,
+				vsi->seid);
+		else
 			goto end_unlock;
-
-		credits = max_tx_rate;
-		do_div(credits, I40E_BW_CREDIT_DIVISOR);
-		dev_dbg(&vsi->back->pdev->dev,
-			"Set tx rate of %llu Mbps (count of 50Mbps %llu) for vsi->seid %u\n",
-			max_tx_rate,
-			credits,
-			vsi->seid);
 	}
 
 	ret = i40e_rebuild_cloud_filters(vsi, vsi->seid);
-- 
2.9.0