drivers: mdio: mdio_xilinx_axienet: Add access timeouts

Previously if the MDIO access failed to complete, the driver could enter
an infinite busy loop. Add timeouts to fail the operation if the
hardware fails to respond within a reasonable time.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>

Author: robhancocksed

drivers/mdio/mdio_xilinx_axienet.c

@@ -93,6 +93,7 @@ static void enable_mdio_bus(const struct mdio_xilinx_axienet_config *config,
 	if ((xilinx_axienet_read_mdio_register(config, XILINX_AXIENET_MDIO_SETUP_REG_OFFSET) &
 	     XILINX_AXIENET_MDIO_SETUP_REG_MDIO_ENABLE_MASK) == 0) {
 		int err;
+		int count = 0;
 
 		xilinx_axienet_mdio_write_register(config, XILINX_AXIENET_MDIO_SETUP_REG_OFFSET,
 						   XILINX_AXIENET_MDIO_SETUP_REG_MDIO_ENABLE_MASK |
@@ -103,7 +104,7 @@ static void enable_mdio_bus(const struct mdio_xilinx_axienet_config *config,
 						   XILINX_AXIENET_MDIO_INTERRUPT_MASK);
 
 		if (config->have_irq) {
-			LOG_DBG("Waiting for bus enable!");
+			LOG_DBG("Waiting for bus enable IRQ");
 			err = k_sem_take(&data->irq_sema,
 					 K_MSEC(XILINX_AXIENET_MDIO_INTERRUPT_TIMEOUT_MS));
 
@@ -115,7 +116,12 @@ static void enable_mdio_bus(const struct mdio_xilinx_axienet_config *config,
 		while ((xilinx_axienet_read_mdio_register(config,
 							  XILINX_AXIENET_MDIO_SETUP_REG_OFFSET) &
 			XILINX_AXIENET_MDIO_SETUP_REG_MDIO_ENABLE_MASK) == 0) {
-			LOG_DBG("Waiting for bus enable!");
+			LOG_DBG("Waiting for bus enable flag");
+			k_busy_wait(1);
+			if (count++ > 1000) {
+				LOG_ERR("MDIO bus enable timeout");
+				return;
+			}
 		}
 
 	} else {
@@ -164,6 +170,7 @@ static int mdio_xilinx_axienet_read(const struct device *dev, uint8_t prtad, uin
 	const struct mdio_xilinx_axienet_config *config = dev->config;
 	struct mdio_xilinx_axienet_data *dev_data = dev->data;
 	int err;
+	int count = 0;
 
 	if (k_is_in_isr()) {
 		LOG_ERR("Called MDIO read in ISR!");
@@ -201,6 +208,11 @@ static int mdio_xilinx_axienet_read(const struct device *dev, uint8_t prtad, uin
 	while ((xilinx_axienet_read_mdio_register(config, XILINX_AXIENET_MDIO_CONTROL_REG_OFFSET) &
 		XILINX_AXIENET_MDIO_CONTROL_REG_MASK_READY) == 0x0) {
 		LOG_DBG("Transfer is not yet ready!");
+		k_busy_wait(1);
+		if (count++ > 1000) {
+			LOG_ERR("MDIO read timeout");
+			return -ETIMEDOUT;
+		}
 	}
 
 	LOG_DBG("IRQ from MDIO received - read complete!");
@@ -220,6 +232,7 @@ static int mdio_xilinx_axienet_write(const struct device *dev, uint8_t prtad, ui
 	const struct mdio_xilinx_axienet_config *config = dev->config;
 	struct mdio_xilinx_axienet_data *dev_data = dev->data;
 	int err;
+	int count = 0;
 
 	if (k_is_in_isr()) {
 		LOG_ERR("Called MDIO write in ISR!");
@@ -257,6 +270,11 @@ static int mdio_xilinx_axienet_write(const struct device *dev, uint8_t prtad, ui
 	while ((xilinx_axienet_read_mdio_register(config, XILINX_AXIENET_MDIO_CONTROL_REG_OFFSET) &
 		XILINX_AXIENET_MDIO_CONTROL_REG_MASK_READY) == 0x0) {
 		LOG_DBG("IRQ from MDIO received but transfer is not yet ready!");
+		k_busy_wait(1);
+		if (count++ > 1000) {
+			LOG_ERR("MDIO write timeout");
+			return -ETIMEDOUT;
+		}
 	}
 
 	LOG_DBG("IRQ from MDIO received - write complete!");