drivers: ethernet: litex: use tx interrupt

use tx interrupt to check, if we can send something,
instead of checking the register periodically.

Signed-off-by: Fin Maaß <[email protected]>

Author: maass-hamburg

drivers/ethernet/eth_litex_liteeth.c

@@ -27,7 +27,7 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 
 #include "eth.h"
 
-#define MAX_TX_FAILURE 100
+#define MAX_TX_FAILURE K_MSEC(100)
 
 #define ETH_LITEX_SLOT_SIZE 0x0800
 
@@ -36,6 +36,7 @@ struct eth_litex_dev_data {
 	uint8_t mac_addr[6];
 	uint8_t txslot;
 	struct k_mutex tx_mutex;
+	struct k_sem sem_tx_ready;
 };
 
 struct eth_litex_config {
@@ -64,12 +65,10 @@ static int eth_initialize(const struct device *dev)
 	struct eth_litex_dev_data *context = dev->data;
 
 	k_mutex_init(&context->tx_mutex);
+	k_sem_init(&context->sem_tx_ready, 1, 1);
 
 	config->config_func(dev);
 
-	/* TX event is disabled because it isn't used by this driver */
-	litex_write8(0, config->tx_ev_enable_addr);
-
 	if (config->random_mac_address) {
 		/* generate random MAC address */
 		gen_random_mac(context->mac_addr, 0x10, 0xe2, 0xd5);
@@ -83,7 +82,7 @@ static int eth_tx(const struct device *dev, struct net_pkt *pkt)
 	uint16_t len;
 	struct eth_litex_dev_data *context = dev->data;
 	const struct eth_litex_config *config = dev->config;
-	int attempts = 0;
+	int ret;
 
 	k_mutex_lock(&context->tx_mutex, K_FOREVER);
 
@@ -97,13 +96,10 @@ static int eth_tx(const struct device *dev, struct net_pkt *pkt)
 	litex_write16(len, config->tx_length_addr);
 
 	/* wait for the device to be ready to transmit */
-	while (litex_read8(config->tx_ready_addr) == 0) {
-		if (attempts++ == MAX_TX_FAILURE) {
-			goto error;
-		}
-		k_sleep(K_MSEC(1));
-	}
-
+	ret = k_sem_take(&context->sem_tx_ready, MAX_TX_FAILURE);
+	if (ret < 0) {
+		goto error;
+	};
 	/* start transmitting */
 	litex_write8(1, config->tx_start_addr);
 
@@ -166,12 +162,13 @@ static void eth_rx(const struct device *port)
 
 static void eth_irq_handler(const struct device *port)
 {
+	struct eth_litex_dev_data *context = port->data;
 	const struct eth_litex_config *config = port->config;
 	/* check sram reader events (tx) */
 	if (litex_read8(config->tx_ev_pending_addr) & BIT(0)) {
-		/* TX event is not enabled nor used by this driver; ack just
-		 * in case if some rogue TX event appeared
-		 */
+		k_sem_give(&context->sem_tx_ready);
+
+		/* ack reader irq */
 		litex_write8(BIT(0), config->tx_ev_pending_addr);
 	}
 
@@ -205,8 +202,14 @@ static int eth_set_config(const struct device *dev, enum ethernet_config_type ty
 
 static int eth_start(const struct device *dev)
 {
+	struct eth_litex_dev_data *context = dev->data;
 	const struct eth_litex_config *config = dev->config;
 
+	if (litex_read8(config->tx_ready_addr)) {
+		k_sem_give(&context->sem_tx_ready);
+	}
+
+	litex_write8(1, config->tx_ev_enable_addr);
 	litex_write8(1, config->rx_ev_enable_addr);
 
 	litex_write8(BIT(0), config->tx_ev_pending_addr);
@@ -219,6 +222,7 @@ static int eth_stop(const struct device *dev)
 {
 	const struct eth_litex_config *config = dev->config;
 
+	litex_write8(0, config->tx_ev_enable_addr);
 	litex_write8(0, config->rx_ev_enable_addr);
 
 	return 0;