net: ethernet: ti: am65-cpsw-qos: Add Frame Preemption MAC Merge support

Add driver support for viewing / changing the MAC Merge sublayer
parameters and seeing the verification state machine's current state
via ethtool.

As hardware does not support interrupt notification for verification
events we resort to polling on link up. On link up we try a couple of
times for verification success and if unsuccessful then give up.

The Frame Preemption feature is described in the Technical Reference
Manual [1] in section:
	12.3.1.4.6.7 Intersperced Express Traffic (IET – P802.3br/D2.0)

Due to Silicon Errata i2208 [2] we set limit min IET fragment size to
124 (excluding 4 bytes mCRC).

[1] AM62x TRM - https://www.ti.com/lit/ug/spruiv7a/spruiv7a.pdf
[2] AM62x Silicon Errata - https://www.ti.com/lit/er/sprz487c/sprz487c.pdf

Signed-off-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 174 insertions, 0 deletions

diff --git a/drivers/net/ethernet/ti/am65-cpsw-qos.c b/drivers/net/ethernet/ti/am65-cpsw-qos.c
index 7790d739e74e..816e73a3d6e4 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-qos.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-qos.c
@@ -4,6 +4,7 @@
  *
  * quality of service module includes:
  * Enhanced Scheduler Traffic (EST - P802.1Qbv/D2.2)
+ * Interspersed Express Traffic (IET - P802.3br/D2.0)
  */
 
 #include <linux/pm_runtime.h>
@@ -25,6 +26,8 @@ enum timer_act {
 	TACT_SKIP_PROG,		/* just buffer can be updated */
 };
 
+static void am65_cpsw_iet_change_preemptible_tcs(struct am65_cpsw_port *port, u8 preemptible_tcs);
+
 static u32
 am65_cpsw_qos_tx_rate_calc(u32 rate_mbps, unsigned long bus_freq)
 {
@@ -192,6 +195,8 @@ static void am65_cpsw_reset_tc_mqprio(struct net_device *ndev)
 
 	/* Reset all Queue priorities to 0 */
 	writel(0, port->port_base + AM65_CPSW_PN_REG_TX_PRI_MAP);
+
+	am65_cpsw_iet_change_preemptible_tcs(port, 0);
 }
 
 static int am65_cpsw_setup_mqprio(struct net_device *ndev, void *type_data)
@@ -254,6 +259,7 @@ static int am65_cpsw_setup_mqprio(struct net_device *ndev, void *type_data)
 	writel(tx_prio_map, port->port_base + AM65_CPSW_PN_REG_TX_PRI_MAP);
 
 	am65_cpsw_tx_pn_shaper_apply(port);
+	am65_cpsw_iet_change_preemptible_tcs(port, mqprio->preemptible_tcs);
 
 exit_put:
 	pm_runtime_put(common->dev);
@@ -261,6 +267,171 @@ exit_put:
 	return ret;
 }
 
+static int am65_cpsw_iet_set_verify_timeout_count(struct am65_cpsw_port *port)
+{
+	int verify_time_ms = port->qos.iet.verify_time_ms;
+	u32 val;
+
+	/* The number of wireside clocks contained in the verify
+	 * timeout counter. The default is 0x1312d0
+	 * (10ms at 125Mhz in 1G mode).
+	 */
+	val = 125 * HZ_PER_MHZ;	/* assuming 125MHz wireside clock */
+
+	val /= MILLIHZ_PER_HZ;		/* count per ms timeout */
+	val *= verify_time_ms;		/* count for timeout ms */
+
+	if (val > AM65_CPSW_PN_MAC_VERIFY_CNT_MASK)
+		return -EINVAL;
+
+	writel(val, port->port_base + AM65_CPSW_PN_REG_IET_VERIFY);
+
+	return 0;
+}
+
+static int am65_cpsw_iet_verify_wait(struct am65_cpsw_port *port)
+{
+	u32 ctrl, status;
+	int try;
+
+	try = 20;
+	do {
+		/* Reset the verify state machine by writing 1
+		 * to LINKFAIL
+		 */
+		ctrl = readl(port->port_base + AM65_CPSW_PN_REG_IET_CTRL);
+		ctrl |= AM65_CPSW_PN_IET_MAC_LINKFAIL;
+		writel(ctrl, port->port_base + AM65_CPSW_PN_REG_IET_CTRL);
+
+		/* Clear MAC_LINKFAIL bit to start Verify. */
+		ctrl = readl(port->port_base + AM65_CPSW_PN_REG_IET_CTRL);
+		ctrl &= ~AM65_CPSW_PN_IET_MAC_LINKFAIL;
+		writel(ctrl, port->port_base + AM65_CPSW_PN_REG_IET_CTRL);
+
+		msleep(port->qos.iet.verify_time_ms);
+
+		status = readl(port->port_base + AM65_CPSW_PN_REG_IET_STATUS);
+		if (status & AM65_CPSW_PN_MAC_VERIFIED)
+			return 0;
+
+		if (status & AM65_CPSW_PN_MAC_VERIFY_FAIL) {
+			netdev_dbg(port->ndev,
+				   "MAC Merge verify failed, trying again\n");
+			continue;
+		}
+
+		if (status & AM65_CPSW_PN_MAC_RESPOND_ERR) {
+			netdev_dbg(port->ndev, "MAC Merge respond error\n");
+			return -ENODEV;
+		}
+
+		if (status & AM65_CPSW_PN_MAC_VERIFY_ERR) {
+			netdev_dbg(port->ndev, "MAC Merge verify error\n");
+			return -ENODEV;
+		}
+	} while (try-- > 0);
+
+	netdev_dbg(port->ndev, "MAC Merge verify timeout\n");
+	return -ETIMEDOUT;
+}
+
+static void am65_cpsw_iet_set_preempt_mask(struct am65_cpsw_port *port, u8 preemptible_tcs)
+{
+	u32 val;
+
+	val = readl(port->port_base + AM65_CPSW_PN_REG_IET_CTRL);
+	val &= ~AM65_CPSW_PN_IET_MAC_PREMPT_MASK;
+	val |= AM65_CPSW_PN_IET_MAC_SET_PREEMPT(preemptible_tcs);
+	writel(val, port->port_base + AM65_CPSW_PN_REG_IET_CTRL);
+}
+
+/* enable common IET_ENABLE only if at least 1 port has rx IET enabled.
+ * UAPI doesn't allow tx enable without rx enable.
+ */
+void am65_cpsw_iet_common_enable(struct am65_cpsw_common *common)
+{
+	struct am65_cpsw_port *port;
+	bool rx_enable = false;
+	u32 val;
+	int i;
+
+	for (i = 0; i < common->port_num; i++) {
+		port = &common->ports[i];
+		val = readl(port->port_base + AM65_CPSW_PN_REG_CTL);
+		rx_enable = !!(val & AM65_CPSW_PN_CTL_IET_PORT_EN);
+		if (rx_enable)
+			break;
+	}
+
+	val = readl(common->cpsw_base + AM65_CPSW_REG_CTL);
+
+	if (rx_enable)
+		val |= AM65_CPSW_CTL_IET_EN;
+	else
+		val &= ~AM65_CPSW_CTL_IET_EN;
+
+	writel(val, common->cpsw_base + AM65_CPSW_REG_CTL);
+	common->iet_enabled = rx_enable;
+}
+
+/* CPSW does not have an IRQ to notify changes to the MAC Merge TX status
+ * (active/inactive), but the preemptible traffic classes should only be
+ * committed to hardware once TX is active. Resort to polling.
+ */
+void am65_cpsw_iet_commit_preemptible_tcs(struct am65_cpsw_port *port)
+{
+	u8 preemptible_tcs;
+	int err;
+	u32 val;
+
+	if (port->qos.link_speed == SPEED_UNKNOWN)
+		return;
+
+	val = readl(port->port_base + AM65_CPSW_PN_REG_CTL);
+	if (!(val & AM65_CPSW_PN_CTL_IET_PORT_EN))
+		return;
+
+	/* update common IET enable */
+	am65_cpsw_iet_common_enable(port->common);
+
+	/* update verify count */
+	err = am65_cpsw_iet_set_verify_timeout_count(port);
+	if (err) {
+		netdev_err(port->ndev, "couldn't set verify count: %d\n", err);
+		return;
+	}
+
+	val = readl(port->port_base + AM65_CPSW_PN_REG_IET_CTRL);
+	if (!(val & AM65_CPSW_PN_IET_MAC_DISABLEVERIFY)) {
+		err = am65_cpsw_iet_verify_wait(port);
+		if (err)
+			return;
+	}
+
+	preemptible_tcs = port->qos.iet.preemptible_tcs;
+	am65_cpsw_iet_set_preempt_mask(port, preemptible_tcs);
+}
+
+static void am65_cpsw_iet_change_preemptible_tcs(struct am65_cpsw_port *port, u8 preemptible_tcs)
+{
+	struct am65_cpsw_ndev_priv *priv = am65_ndev_to_priv(port->ndev);
+
+	port->qos.iet.preemptible_tcs = preemptible_tcs;
+	mutex_lock(&priv->mm_lock);
+	am65_cpsw_iet_commit_preemptible_tcs(port);
+	mutex_unlock(&priv->mm_lock);
+}
+
+static void am65_cpsw_iet_link_state_update(struct net_device *ndev)
+{
+	struct am65_cpsw_ndev_priv *priv = am65_ndev_to_priv(ndev);
+	struct am65_cpsw_port *port = am65_ndev_to_port(ndev);
+
+	mutex_lock(&priv->mm_lock);
+	am65_cpsw_iet_commit_preemptible_tcs(port);
+	mutex_unlock(&priv->mm_lock);
+}
+
 static int am65_cpsw_port_est_enabled(struct am65_cpsw_port *port)
 {
 	return port->qos.est_oper || port->qos.est_admin;
@@ -737,6 +908,7 @@ static int am65_cpsw_taprio_replace(struct net_device *ndev,
 
 	devm_kfree(&ndev->dev, port->qos.est_admin);
 	port->qos.est_admin = est_new;
+	am65_cpsw_iet_change_preemptible_tcs(port, taprio->mqprio.preemptible_tcs);
 
 	return 0;
 
@@ -1116,6 +1288,7 @@ void am65_cpsw_qos_link_up(struct net_device *ndev, int link_speed)
 
 	port->qos.link_speed = link_speed;
 	am65_cpsw_tx_pn_shaper_apply(port);
+	am65_cpsw_iet_link_state_update(ndev);
 
 	am65_cpsw_est_link_up(ndev, link_speed);
 	port->qos.link_down_time = 0;
@@ -1127,6 +1300,7 @@ void am65_cpsw_qos_link_down(struct net_device *ndev)
 
 	port->qos.link_speed = SPEED_UNKNOWN;
 	am65_cpsw_tx_pn_shaper_apply(port);
+	am65_cpsw_iet_link_state_update(ndev);
 
 	if (!port->qos.link_down_time)
 		port->qos.link_down_time = ktime_get();