spi: zynqmp-gqspi: Clean up fillgenfifo

This function does a lot more work (assigning things multiple times,
masking unnecessarily, comparing to zero, using superfluous parentheses)
than it needs to. This makes it difficult to understand and modify.
Clean it up. No functional change intended.

Signed-off-by: Sean Anderson <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: Sean Anderson

drivers/spi/spi-zynqmp-gqspi.c

@@ -82,7 +82,6 @@
 #define GQSPI_GENFIFO_RX			0x00020000
 #define GQSPI_GENFIFO_STRIPE			0x00040000
 #define GQSPI_GENFIFO_POLL			0x00080000
-#define GQSPI_GENFIFO_EXP_START			0x00000100
 #define GQSPI_FIFO_CTRL_RST_RX_FIFO_MASK	0x00000004
 #define GQSPI_FIFO_CTRL_RST_TX_FIFO_MASK	0x00000002
 #define GQSPI_FIFO_CTRL_RST_GEN_FIFO_MASK	0x00000001
@@ -672,71 +671,50 @@ static void zynqmp_qspi_readrxfifo(struct zynqmp_qspi *xqspi, u32 size)
 static void zynqmp_qspi_fillgenfifo(struct zynqmp_qspi *xqspi, u8 nbits,
 				    u32 genfifoentry)
 {
-	u32 transfer_len = 0;
+	u32 transfer_len, tempcount, exponent;
+	u8 imm_data;
 
-	if (xqspi->txbuf) {
-		genfifoentry &= ~GQSPI_GENFIFO_RX;
-		genfifoentry |= GQSPI_GENFIFO_DATA_XFER;
-		genfifoentry |= GQSPI_GENFIFO_TX;
-		transfer_len = xqspi->bytes_to_transfer;
-	} else if (xqspi->rxbuf) {
-		genfifoentry &= ~GQSPI_GENFIFO_TX;
-		genfifoentry |= GQSPI_GENFIFO_DATA_XFER;
+	genfifoentry |= GQSPI_GENFIFO_DATA_XFER;
+	if (xqspi->rxbuf) {
 		genfifoentry |= GQSPI_GENFIFO_RX;
 		if (xqspi->mode == GQSPI_MODE_DMA)
 			transfer_len = xqspi->dma_rx_bytes;
 		else
 			transfer_len = xqspi->bytes_to_receive;
 	} else {
-		/* Sending dummy circles here */
-		genfifoentry &= ~(GQSPI_GENFIFO_TX | GQSPI_GENFIFO_RX);
-		genfifoentry |= GQSPI_GENFIFO_DATA_XFER;
 		transfer_len = xqspi->bytes_to_transfer;
 	}
+
+	if (xqspi->txbuf)
+		genfifoentry |= GQSPI_GENFIFO_TX;
+
 	genfifoentry |= zynqmp_qspi_selectspimode(xqspi, nbits);
 	xqspi->genfifoentry = genfifoentry;
 	dev_dbg(xqspi->dev, "genfifo %05x transfer_len %u\n",
 		genfifoentry, transfer_len);
 
-	if ((transfer_len) < GQSPI_GENFIFO_IMM_DATA_MASK) {
-		genfifoentry &= ~GQSPI_GENFIFO_IMM_DATA_MASK;
-		genfifoentry |= transfer_len;
-		zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, genfifoentry);
-	} else {
-		int tempcount = transfer_len;
-		u32 exponent = 8;	/* 2^8 = 256 */
-		u8 imm_data = tempcount & 0xFF;
-
-		tempcount &= ~(tempcount & 0xFF);
-		/* Immediate entry */
-		if (tempcount != 0) {
-			/* Exponent entries */
-			genfifoentry |= GQSPI_GENFIFO_EXP;
-			while (tempcount != 0) {
-				if (tempcount & GQSPI_GENFIFO_EXP_START) {
-					genfifoentry &=
-						~GQSPI_GENFIFO_IMM_DATA_MASK;
-					genfifoentry |= exponent;
-					zynqmp_gqspi_write(xqspi,
-							   GQSPI_GEN_FIFO_OFST,
-							   genfifoentry);
-				}
-				tempcount = tempcount >> 1;
-				exponent++;
-			}
-		}
-		if (imm_data != 0) {
-			genfifoentry &= ~GQSPI_GENFIFO_EXP;
-			genfifoentry &= ~GQSPI_GENFIFO_IMM_DATA_MASK;
-			genfifoentry |= (u8)(imm_data & 0xFF);
+	/* Exponent entries */
+	imm_data = transfer_len;
+	tempcount = transfer_len >> 8;
+	exponent = 8;
+	genfifoentry |= GQSPI_GENFIFO_EXP;
+	while (tempcount) {
+		if (tempcount & 1)
 			zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST,
-					   genfifoentry);
-		}
-	}
-	if (xqspi->mode == GQSPI_MODE_IO && xqspi->rxbuf) {
-		/* Dummy generic FIFO entry */
-		zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, 0x0);
+					   genfifoentry | exponent);
+		tempcount >>= 1;
+		exponent++;
 	}
+
+	/* Immediate entry */
+	genfifoentry &= ~GQSPI_GENFIFO_EXP;
+	if (imm_data)
+		zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST,
+				   genfifoentry | imm_data);
+
+	/* Dummy generic FIFO entry */
+	if (xqspi->mode == GQSPI_MODE_IO && xqspi->rxbuf)
+		zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, 0);
 }
 
 /**