net: dsa: microchip: add support for credit based shaper

KSZ9477, KSZ9567, KSZ9563, KSZ8563 and LAN937x supports Credit based
shaper. To differentiate the chip supporting cbs, tc_cbs_supported
flag is introduced in ksz_chip_data.
And KSZ series has 16bit Credit increment registers whereas LAN937x has
24bit register. The value to be programmed in the credit increment is
determined using the successive multiplication method to convert decimal
fraction to hexadecimal fraction.
For example: if idleslope is 10000 and sendslope is -90000, then
bandwidth is 10000 - (-90000) = 100000.
The 10% bandwidth of 100Mbps means 10/100 = 0.1(decimal). This value has
to be converted to hexa.
1) 0.1 * 16 = 1.6  --> fraction 0.6 Carry = 1 (MSB)
2) 0.6 * 16 = 9.6  --> fraction 0.6 Carry = 9
3) 0.6 * 16 = 9.6  --> fraction 0.6 Carry = 9
4) 0.6 * 16 = 9.6  --> fraction 0.6 Carry = 9
5) 0.6 * 16 = 9.6  --> fraction 0.6 Carry = 9
6) 0.6 * 16 = 9.6  --> fraction 0.6 Carry = 9 (LSB)
Now 0.1(decimal) becomes 0.199999(Hex).
If it is LAN937x, 24 bit value will be programmed to Credit Inc
register, 0x199999. For others 16 bit value will be prgrammed, 0x1999.

Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 112 insertions, 0 deletions

diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 9d4dcbe2949b..46becc0382d6 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -23,6 +23,7 @@
 #include <linux/of_net.h>
 #include <linux/micrel_phy.h>
 #include <net/dsa.h>
+#include <net/pkt_cls.h>
 #include <net/switchdev.h>
 
 #include "ksz_common.h"
@@ -31,6 +32,10 @@
 #include "ksz9477.h"
 #include "lan937x.h"
 
+#define KSZ_CBS_ENABLE ((MTI_SCHEDULE_STRICT_PRIO << MTI_SCHEDULE_MODE_S) | \
+			(MTI_SHAPING_SRP << MTI_SHAPING_S))
+#define KSZ_CBS_DISABLE ((MTI_SCHEDULE_WRR << MTI_SCHEDULE_MODE_S) |\
+			 (MTI_SHAPING_OFF << MTI_SHAPING_S))
 #define MIB_COUNTER_NUM 0x20
 
 struct ksz_stats_raw {
@@ -250,6 +255,7 @@ static const struct ksz_dev_ops ksz9477_dev_ops = {
 	.change_mtu = ksz9477_change_mtu,
 	.phylink_mac_link_up = ksz9477_phylink_mac_link_up,
 	.config_cpu_port = ksz9477_config_cpu_port,
+	.tc_cbs_set_cinc = ksz9477_tc_cbs_set_cinc,
 	.enable_stp_addr = ksz9477_enable_stp_addr,
 	.reset = ksz9477_reset_switch,
 	.init = ksz9477_switch_init,
@@ -286,6 +292,7 @@ static const struct ksz_dev_ops lan937x_dev_ops = {
 	.change_mtu = lan937x_change_mtu,
 	.phylink_mac_link_up = ksz9477_phylink_mac_link_up,
 	.config_cpu_port = lan937x_config_cpu_port,
+	.tc_cbs_set_cinc = lan937x_tc_cbs_set_cinc,
 	.enable_stp_addr = ksz9477_enable_stp_addr,
 	.reset = lan937x_reset_switch,
 	.init = lan937x_switch_init,
@@ -1081,6 +1088,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.port_cnt = 3,		/* total port count */
 		.port_nirqs = 3,
 		.num_tx_queues = 4,
+		.tc_cbs_supported = true,
 		.ops = &ksz9477_dev_ops,
 		.mib_names = ksz9477_mib_names,
 		.mib_cnt = ARRAY_SIZE(ksz9477_mib_names),
@@ -1219,6 +1227,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.port_cnt = 7,		/* total physical port count */
 		.port_nirqs = 4,
 		.num_tx_queues = 4,
+		.tc_cbs_supported = true,
 		.ops = &ksz9477_dev_ops,
 		.phy_errata_9477 = true,
 		.mib_names = ksz9477_mib_names,
@@ -1342,6 +1351,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.port_cnt = 3,		/* total port count */
 		.port_nirqs = 3,
 		.num_tx_queues = 4,
+		.tc_cbs_supported = true,
 		.ops = &ksz9477_dev_ops,
 		.mib_names = ksz9477_mib_names,
 		.mib_cnt = ARRAY_SIZE(ksz9477_mib_names),
@@ -1368,6 +1378,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.port_cnt = 7,		/* total physical port count */
 		.port_nirqs = 3,
 		.num_tx_queues = 4,
+		.tc_cbs_supported = true,
 		.ops = &ksz9477_dev_ops,
 		.phy_errata_9477 = true,
 		.mib_names = ksz9477_mib_names,
@@ -1399,6 +1410,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.port_cnt = 5,		/* total physical port count */
 		.port_nirqs = 6,
 		.num_tx_queues = 8,
+		.tc_cbs_supported = true,
 		.ops = &lan937x_dev_ops,
 		.mib_names = ksz9477_mib_names,
 		.mib_cnt = ARRAY_SIZE(ksz9477_mib_names),
@@ -1424,6 +1436,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.port_cnt = 6,		/* total physical port count */
 		.port_nirqs = 6,
 		.num_tx_queues = 8,
+		.tc_cbs_supported = true,
 		.ops = &lan937x_dev_ops,
 		.mib_names = ksz9477_mib_names,
 		.mib_cnt = ARRAY_SIZE(ksz9477_mib_names),
@@ -1449,6 +1462,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.port_cnt = 8,		/* total physical port count */
 		.port_nirqs = 6,
 		.num_tx_queues = 8,
+		.tc_cbs_supported = true,
 		.ops = &lan937x_dev_ops,
 		.mib_names = ksz9477_mib_names,
 		.mib_cnt = ARRAY_SIZE(ksz9477_mib_names),
@@ -1478,6 +1492,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.port_cnt = 5,		/* total physical port count */
 		.port_nirqs = 6,
 		.num_tx_queues = 8,
+		.tc_cbs_supported = true,
 		.ops = &lan937x_dev_ops,
 		.mib_names = ksz9477_mib_names,
 		.mib_cnt = ARRAY_SIZE(ksz9477_mib_names),
@@ -1507,6 +1522,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.port_cnt = 8,		/* total physical port count */
 		.port_nirqs = 6,
 		.num_tx_queues = 8,
+		.tc_cbs_supported = true,
 		.ops = &lan937x_dev_ops,
 		.mib_names = ksz9477_mib_names,
 		.mib_cnt = ARRAY_SIZE(ksz9477_mib_names),
@@ -2976,6 +2992,101 @@ static int ksz_switch_detect(struct ksz_device *dev)
 	return 0;
 }
 
+/* Bandwidth is calculated by idle slope/transmission speed. Then the Bandwidth
+ * is converted to Hex-decimal using the successive multiplication method. On
+ * every step, integer part is taken and decimal part is carry forwarded.
+ */
+static int cinc_cal(s32 idle_slope, s32 send_slope, u32 *bw)
+{
+	u32 cinc = 0;
+	u32 txrate;
+	u32 rate;
+	u8 temp;
+	u8 i;
+
+	txrate = idle_slope - send_slope;
+
+	if (!txrate)
+		return -EINVAL;
+
+	rate = idle_slope;
+
+	/* 24 bit register */
+	for (i = 0; i < 6; i++) {
+		rate = rate * 16;
+
+		temp = rate / txrate;
+
+		rate %= txrate;
+
+		cinc = ((cinc << 4) | temp);
+	}
+
+	*bw = cinc;
+
+	return 0;
+}
+
+static int ksz_setup_tc_cbs(struct dsa_switch *ds, int port,
+			    struct tc_cbs_qopt_offload *qopt)
+{
+	struct ksz_device *dev = ds->priv;
+	int ret;
+	u32 bw;
+
+	if (!dev->info->tc_cbs_supported)
+		return -EOPNOTSUPP;
+
+	if (qopt->queue > dev->info->num_tx_queues)
+		return -EINVAL;
+
+	/* Queue Selection */
+	ret = ksz_pwrite32(dev, port, REG_PORT_MTI_QUEUE_INDEX__4, qopt->queue);
+	if (ret)
+		return ret;
+
+	if (!qopt->enable)
+		return ksz_pwrite8(dev, port, REG_PORT_MTI_QUEUE_CTRL_0,
+				   KSZ_CBS_DISABLE);
+
+	/* High Credit */
+	ret = ksz_pwrite16(dev, port, REG_PORT_MTI_HI_WATER_MARK,
+			   qopt->hicredit);
+	if (ret)
+		return ret;
+
+	/* Low Credit */
+	ret = ksz_pwrite16(dev, port, REG_PORT_MTI_LO_WATER_MARK,
+			   qopt->locredit);
+	if (ret)
+		return ret;
+
+	/* Credit Increment Register */
+	ret = cinc_cal(qopt->idleslope, qopt->sendslope, &bw);
+	if (ret)
+		return ret;
+
+	if (dev->dev_ops->tc_cbs_set_cinc) {
+		ret = dev->dev_ops->tc_cbs_set_cinc(dev, port, bw);
+		if (ret)
+			return ret;
+	}
+
+	return ksz_pwrite8(dev, port, REG_PORT_MTI_QUEUE_CTRL_0,
+			   KSZ_CBS_ENABLE);
+}
+
+static int ksz_setup_tc(struct dsa_switch *ds, int port,
+			enum tc_setup_type type, void *type_data)
+{
+	switch (type) {
+	case TC_SETUP_QDISC_CBS:
+		return ksz_setup_tc_cbs(ds, port, type_data);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
 static const struct dsa_switch_ops ksz_switch_ops = {
 	.get_tag_protocol	= ksz_get_tag_protocol,
 	.connect_tag_protocol   = ksz_connect_tag_protocol,
@@ -3018,6 +3129,7 @@ static const struct dsa_switch_ops ksz_switch_ops = {
 	.port_hwtstamp_set	= ksz_hwtstamp_set,
 	.port_txtstamp		= ksz_port_txtstamp,
 	.port_rxtstamp		= ksz_port_rxtstamp,
+	.port_setup_tc		= ksz_setup_tc,
 };
 
 struct ksz_device *ksz_switch_alloc(struct device *base, void *priv)