[PATCH 4/8] net: dc2114x: add support for CPUs that have cache between the memory and the card

[Hanyuan Zhao]

This commit adds support for the MIPS and LoongArch CPUs, which would use cache
after they jump into U-Boot. This commit requests the CPU to return the
addresses in uncached windows and flushes the cache in need, to make sure the
memory between the CPU and the network card is in consistency.

Signed-off-by: Hanyuan Zhao <zhaohy22 at mails.tsinghua.edu.cn>
---
 drivers/net/dc2114x.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/net/dc2114x.c b/drivers/net/dc2114x.c
index cf9f78163a..0b3000cc1d 100644
--- a/drivers/net/dc2114x.c
+++ b/drivers/net/dc2114x.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0+
 
 #include <asm/io.h>
+#include <cpu_func.h>
 #include <dm.h>
 #include <malloc.h>
 #include <net.h>
@@ -94,9 +95,17 @@ struct de4x5_desc {
 	u32 next;
 };
 
+/* Assigned for network card's ring buffer:
+ * Some CPU might treat these memories as cached, and changes to these memories
+ * won't immediately be visible to each other. It is necessary to ensure that
+ * these memories between the CPU and the network card are marked as uncached.
+ */
+static struct de4x5_desc rx_ring[NUM_RX_DESC] __aligned(32);
+static struct de4x5_desc tx_ring[NUM_TX_DESC] __aligned(32);
+
 struct dc2114x_priv {
-	struct de4x5_desc rx_ring[NUM_RX_DESC] __aligned(32);
-	struct de4x5_desc tx_ring[NUM_TX_DESC] __aligned(32);
+	struct de4x5_desc *rx_ring; /* Must be uncached to CPU */
+	struct de4x5_desc *tx_ring; /* Must be uncached to CPU */
 	int rx_new;	/* RX descriptor ring pointer */
 	int tx_new;	/* TX descriptor ring pointer */
 	char rx_ring_size;
@@ -276,7 +285,12 @@ static int read_srom(struct dc2114x_priv *priv, u_long ioaddr, int index)
 
 static void send_setup_frame(struct dc2114x_priv *priv)
 {
-	char setup_frame[SETUP_FRAME_LEN];
+	/* We are writing setup frame and these changes should be visible to the
+	 * network card immediately. So let's directly read/write through the
+	 * uncached window.
+	 */
+	char __setup_frame[SETUP_FRAME_LEN] __aligned(32);
+	char *setup_frame = (char *)map_physmem((phys_addr_t)virt_to_phys(__setup_frame), 0, MAP_NOCACHE);
 	char *pa = &setup_frame[0];
 	int i;
 
@@ -337,6 +351,9 @@ static int dc21x4x_send_common(struct dc2114x_priv *priv, void *packet, int leng
 		goto done;
 	}
 
+	/* Packet should be visible to the network card */
+	flush_dcache_range((phys_addr_t)packet, (phys_addr_t)(packet + RX_BUFF_SZ));
+
 	priv->tx_ring[priv->tx_new].buf = cpu_to_le32(phys_to_bus(priv->devno,
 						      (u32)packet));
 	priv->tx_ring[priv->tx_new].des1 = cpu_to_le32(TD_TER | TD_LS | TD_FS | length);
@@ -533,7 +550,8 @@ static int dc2114x_recv(struct udevice *dev, int flags, uchar **packetp)
 	if (!ret)
 		return 0;
 
-	*packetp = net_rx_packets[priv->rx_new];
+	invalidate_dcache_range((phys_addr_t)net_rx_packets[priv->rx_new], (phys_addr_t)(net_rx_packets[priv->rx_new] + RX_BUFF_SZ));
+	*packetp = (uchar *)net_rx_packets[priv->rx_new];
 
 	return ret - 4;
 }
@@ -597,6 +615,9 @@ static int dc2114x_probe(struct udevice *dev)
 
 	priv->devno = dev;
 	priv->enetaddr = plat->enetaddr;
+	priv->rx_ring = (struct de4x5_desc *)map_physmem((phys_addr_t)virt_to_phys(rx_ring), 0, MAP_NOCACHE);
+	priv->tx_ring = (struct de4x5_desc *)map_physmem((phys_addr_t)virt_to_phys(tx_ring), 0, MAP_NOCACHE);
+
 	return 0;
 }
 
-- 
2.39.2