net: xilinx: axienet: Add some symbolic constants for IRQ delay timer

Instead of using literals, add some symbolic constants for the IRQ delay
timer calculation.

Signed-off-by: Sean Anderson <[email protected]>
Reviewed by: Shannon Nelson <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Sean Anderson

drivers/net/ethernet/xilinx/xilinx_axienet.h

@@ -120,6 +120,9 @@
 #define XAXIDMA_IRQ_ERROR_MASK		0x00004000 /* Error interrupt */
 #define XAXIDMA_IRQ_ALL_MASK		0x00007000 /* All interrupts */
 
+/* Constant to convert delay counts to microseconds */
+#define XAXIDMA_DELAY_SCALE		(125ULL * USEC_PER_SEC)
+
 /* Default TX/RX Threshold and delay timer values for SGDMA mode */
 #define XAXIDMA_DFT_TX_THRESHOLD	24
 #define XAXIDMA_DFT_TX_USEC		50

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -238,11 +238,8 @@ static u32 axienet_usec_to_timer(struct axienet_local *lp, u32 coalesce_usec)
 
 	/* 1 Timeout Interval = 125 * (clock period of SG clock) */
 	result = DIV64_U64_ROUND_CLOSEST((u64)coalesce_usec * clk_rate,
-					 (u64)125000000);
-	if (result > 255)
-		result = 255;
-
-	return result;
+					 XAXIDMA_DELAY_SCALE);
+	return min(result, FIELD_MAX(XAXIDMA_DELAY_MASK));
 }
 
 /**