[PATCH net-next 08/14] net: enetc: add multiple command BD rings support

[Wei Fang <wei.fang@nxp.com>]

All the tables of NETC switch are managed through the command BD ring,
but unlike ENETC, the switch has two command BD rings, if the current
ring is busy, the switch driver can switch to another ring to manage
the table. Currently, the NTMP driver does not support multiple rings.
Therefore, netc_select_cbdr() is added to select a appropriate ring to
execute the command for the switch.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
---
 drivers/net/ethernet/freescale/enetc/ntmp.c | 27 ++++++++++++++++++---
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/freescale/enetc/ntmp.c b/drivers/net/ethernet/freescale/enetc/ntmp.c
index 9fc3422137fc..e23a32946762 100644
--- a/drivers/net/ethernet/freescale/enetc/ntmp.c
+++ b/drivers/net/ethernet/freescale/enetc/ntmp.c
@@ -117,6 +117,25 @@ static void ntmp_clean_cbdr(struct netc_cbdr *cbdr)
 	cbdr->next_to_clean = i;
 }
 
+static struct netc_cbdr *netc_select_cbdr(struct ntmp_user *user)
+{
+	int cpu, i;
+
+	for (i = 0; i < user->cbdr_num; i++) {
+		if (spin_is_locked(&user->ring[i].ring_lock))
+			continue;
+
+		return &user->ring[i];
+	}
+
+	/* If all the command BDRs are busy now, we select
+	 * one of them, but need to wait for a while to use.
+	 */
+	cpu = smp_processor_id();
+
+	return &user->ring[cpu % user->cbdr_num];
+}
+
 static int netc_xmit_ntmp_cmd(struct ntmp_user *user, union netc_cbd *cbd)
 {
 	union netc_cbd *cur_cbd;
@@ -125,10 +144,10 @@ static int netc_xmit_ntmp_cmd(struct ntmp_user *user, union netc_cbd *cbd)
 	u16 status;
 	u32 val;
 
-	/* Currently only i.MX95 ENETC is supported, and it only has one
-	 * command BD ring
-	 */
-	cbdr = &user->ring[0];
+	if (user->cbdr_num == 1)
+		cbdr = &user->ring[0];
+	else
+		cbdr = netc_select_cbdr(user);
 
 	spin_lock_bh(&cbdr->ring_lock);
 
-- 
2.34.1