net: mvpp2: add FCA RXQ non occupied descriptor threshold

RXQ non occupied descriptor threshold would be used by
Flow Control Firmware feature to move to the XOFF mode.
RXQ non occupied threshold would change interrupt cause
that polled by CM3 Firmware.
Actual non occupied interrupt masked and won't trigger interrupt.

Signed-off-by: Stefan Chulski <stefanc@marvell.com>

drivers/net/ethernet/marvell/mvpp2/mvpp2.h

@@ -295,6 +295,8 @@
 #define     MVPP2_PON_CAUSE_TXP_OCCUP_DESC_ALL_MASK	0x3fc00000
 #define     MVPP2_PON_CAUSE_MISC_SUM_MASK		BIT(31)
 #define MVPP2_ISR_MISC_CAUSE_REG		0x55b0
+#define MVPP2_ISR_RX_ERR_CAUSE_REG(port)	(0x5520 + 4 * (port))
+#define	    MVPP2_ISR_RX_ERR_CAUSE_NONOCC_MASK	0x00ff
 
 /* Buffer Manager registers */
 #define MVPP2_BM_POOL_BASE_REG(pool)		(0x6000 + ((pool) * 4))
@@ -764,6 +766,7 @@
 #define MSS_SRAM_SIZE		0x800
 #define FC_QUANTA		0xFFFF
 #define FC_CLK_DIVIDER		0x140
+#define MSS_THRESHOLD_STOP    768
 
 /* RX buffer constants */
 #define MVPP2_SKB_SHINFO_SIZE \

drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c

@@ -1154,6 +1154,9 @@ static void mvpp2_interrupts_mask(void *arg)
 	mvpp2_thread_write(port->priv,
 			   mvpp2_cpu_to_thread(port->priv, smp_processor_id()),
 			   MVPP2_ISR_RX_TX_MASK_REG(port->id), 0);
+	mvpp2_thread_write(port->priv,
+			   mvpp2_cpu_to_thread(port->priv, smp_processor_id()),
+			   MVPP2_ISR_RX_ERR_CAUSE_REG(port->id), 0);
 }
 
 /* Unmask the current thread's Rx/Tx interrupts.
@@ -1177,6 +1180,10 @@ static void mvpp2_interrupts_unmask(void *arg)
 	mvpp2_thread_write(port->priv,
 			   mvpp2_cpu_to_thread(port->priv, smp_processor_id()),
 			   MVPP2_ISR_RX_TX_MASK_REG(port->id), val);
+	mvpp2_thread_write(port->priv,
+			   mvpp2_cpu_to_thread(port->priv, smp_processor_id()),
+			   MVPP2_ISR_RX_ERR_CAUSE_REG(port->id),
+			   MVPP2_ISR_RX_ERR_CAUSE_NONOCC_MASK);
 }
 
 static void
@@ -1201,6 +1208,9 @@ mvpp2_shared_interrupt_mask_unmask(struct mvpp2_port *port, bool mask)
 
 		mvpp2_thread_write(port->priv, v->sw_thread_id,
 				   MVPP2_ISR_RX_TX_MASK_REG(port->id), val);
+		mvpp2_thread_write(port->priv, v->sw_thread_id,
+				   MVPP2_ISR_RX_ERR_CAUSE_REG(port->id),
+				   MVPP2_ISR_RX_ERR_CAUSE_NONOCC_MASK);
 	}
 }
 
@@ -2406,6 +2416,22 @@ static void mvpp2_txp_max_tx_size_set(struct mvpp2_port *port)
 	}
 }
 
+/* Routine set the number of non-occupied descriptors threshold that change
+ * interrupt error cause polled by FW Flow Control
+ */
+void mvpp2_set_rxq_free_tresh(struct mvpp2_port *port,
+			      struct mvpp2_rx_queue *rxq)
+{
+	u32 val;
+
+	mvpp2_write(port->priv, MVPP2_RXQ_NUM_REG, rxq->id);
+
+	val = mvpp2_read(port->priv, MVPP2_RXQ_THRESH_REG);
+	val &= ~MVPP2_RXQ_NON_OCCUPIED_MASK;
+	val |= MSS_THRESHOLD_STOP << MVPP2_RXQ_NON_OCCUPIED_OFFSET;
+	mvpp2_write(port->priv, MVPP2_RXQ_THRESH_REG, val);
+}
+
 /* Set the number of packets that will be received before Rx interrupt
  * will be generated by HW.
  */
@@ -2669,6 +2695,9 @@ static int mvpp2_rxq_init(struct mvpp2_port *port,
 	mvpp2_rx_pkts_coal_set(port, rxq);
 	mvpp2_rx_time_coal_set(port, rxq);
 
+	/* Set the number of non occupied descriptors threshold */
+	mvpp2_set_rxq_free_tresh(port, rxq);
+
 	/* Add number of descriptors ready for receiving packets */
 	mvpp2_rxq_status_update(port, rxq->id, 0, rxq->size);