[openwrt/openwrt] realtek: eth: add new transmit structures

[LEDE Commits]

robimarko pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/2d84c5222cbc68bf3a0cf470afb5839115738a09

commit 2d84c5222cbc68bf3a0cf470afb5839115738a09
Author: Markus Stockhausen <markus.stockhausen at gmx.de>
AuthorDate: Wed Jan 28 18:51:31 2026 +0100

    realtek: eth: add new transmit structures
    
    The ethernet driver will get a new transmit function. As a first
    step add the required structures and initialize them.
    
    To get an idea: In the future the transmit buffer will hold only
    the needed packet header information. The real data is kept in the
    SKBs. So only pointers will be changed and memory moving can be
    avoided. The SoC will transfer packet data directly from the SKBs.
    
    Additionally a new transmit lock will be established that is
    separated from the current driver lock. This is only needed
    to guard the "kick-the-engine" command. So contention of the old
    global lock can be reduced.
    
    Signed-off-by: Markus Stockhausen <markus.stockhausen at gmx.de>
    Link: https://github.com/openwrt/openwrt/pull/21778
    Signed-off-by: Robert Marko <robimarko at gmail.com>
---
 .../files-6.12/drivers/net/ethernet/rtl838x_eth.c  | 44 ++++++++++++++++++++++
 .../files-6.12/drivers/net/ethernet/rtl838x_eth.h  |  1 +
 2 files changed, 45 insertions(+)

diff --git a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
index 39bf092a8e..3f5621179a 100644
--- a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
+++ b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
@@ -32,6 +32,11 @@ int rtl83xx_setup_tc(struct net_device *dev, enum tc_setup_type type, void *type
  * for an RX ring, MAX_ENTRIES the maximum number of entries
  * available in total for all queues.
  */
+
+#define RTETH_OWN_CPU		1
+#define RTETH_TX_RING_SIZE	16
+#define RTETH_TX_RINGS		2
+
 #define MAX_RXRINGS	32
 #define MAX_RXLEN	300
 #define MAX_ENTRIES	(300 * 8)
@@ -50,6 +55,24 @@ int rtl83xx_setup_tc(struct net_device *dev, enum tc_setup_type type, void *type
 #define WRAP		0x2
 #define RING_BUFFER	1600
 
+struct rteth_packet {
+	/* hardware header part as required by SoC */
+	dma_addr_t		dma;
+	u16			reserved;
+	u16			size;
+	u16			offset;
+	u16			len;
+	u16			cpu_tag[10];
+	/* software mangement and data part */
+	struct sk_buff		*skb;
+} __packed __aligned(1);
+
+struct rteth_tx {
+	int			slot;
+	dma_addr_t		ring[RTETH_TX_RING_SIZE];
+	struct rteth_packet	packet[RTETH_TX_RING_SIZE];
+};
+
 struct p_hdr {
 	u8	*buf;
 	u16	reserved;
@@ -197,6 +220,10 @@ struct rteth_ctrl {
 	u32 lastEvent;
 	u16 rxrings;
 	u16 rxringlen;
+	/* transmit handling */
+	dma_addr_t		tx_dma;
+	spinlock_t		tx_lock;
+	struct rteth_tx		*tx_data;
 };
 
 /* On the RTL93XX, the RTL93XX_DMA_IF_RX_RING_CNTR track the fill level of
@@ -662,6 +689,19 @@ static void rteth_setup_ring_buffer(struct rteth_ctrl *ctrl, struct ring_b *ring
 		ring->tx_r[i][j - 1] |= WRAP;
 		ring->c_tx[i] = 0;
 	}
+
+	for (int r = 0; r < RTETH_TX_RINGS; r++) {
+		for (int i = 0; i < RTETH_TX_RING_SIZE; i++) {
+			ctrl->tx_data[r].packet[i].skb = NULL;
+			ctrl->tx_data[r].ring[i] = ctrl->tx_dma +
+						   sizeof(struct rteth_tx) * r +
+						   offsetof(struct rteth_tx, packet) +
+						   sizeof(struct rteth_packet) * i;
+		}
+
+		ctrl->tx_data[r].ring[RTETH_TX_RING_SIZE - 1] |= WRAP;
+		ctrl->tx_data[r].slot = 0;
+	}
 }
 
 static void rtl839x_setup_notify_ring_buffer(struct rteth_ctrl *ctrl)
@@ -1702,7 +1742,11 @@ static int rtl838x_eth_probe(struct platform_device *pdev)
 	ring = ctrl->membase;
 	ring->rx_space = ctrl->membase + sizeof(struct ring_b) + sizeof(struct notify_b);
 
+	ctrl->tx_data = dmam_alloc_coherent(&pdev->dev, sizeof(struct rteth_tx) * RTETH_TX_RINGS,
+					    &ctrl->tx_dma, GFP_KERNEL);
+
 	spin_lock_init(&ctrl->lock);
+	spin_lock_init(&ctrl->tx_lock);
 
 	dev->ethtool_ops = &rteth_ethtool_ops;
 	dev->min_mtu = ETH_ZLEN;
diff --git a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.h b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.h
index d289f4c046..bb64b88d15 100644
--- a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.h
+++ b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.h
@@ -403,6 +403,7 @@ inline u32 rtl931x_get_mac_tx_pause_sts(int p)
 struct p_hdr;
 struct dsa_tag;
 struct rteth_ctrl;
+struct rteth_packet;
 
 struct rteth_config {
 	int family_id;