serial: ce4100: clean up serial_in/out() hooks

ce4100_mem_serial_in() unnecessarily contains 4 nested 'if's. That makes
the code hard to follow. Invert the conditions and return early if the
particular conditions do not hold.

And use "<<=" for shifting the offset in both of the hooks.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: [email protected]
Cc: "H. Peter Anvin" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Jiri Slaby (SUSE)

arch/x86/platform/ce4100/ce4100.c

@@ -53,29 +53,32 @@ static u32 ce4100_mem_serial_in(struct uart_port *p, unsigned int offset)
 {
 	u32 ret, ier, lsr;
 
-	if (offset == UART_IIR) {
-		offset = offset << p->regshift;
-		ret = readl(p->membase + offset);
-		if (ret & UART_IIR_NO_INT) {
-			/* see if the TX interrupt should have really set */
-			ier = mem_serial_in(p, UART_IER);
-			/* see if the UART's XMIT interrupt is enabled */
-			if (ier & UART_IER_THRI) {
-				lsr = mem_serial_in(p, UART_LSR);
-				/* now check to see if the UART should be
-				   generating an interrupt (but isn't) */
-				if (lsr & (UART_LSR_THRE | UART_LSR_TEMT))
-					ret &= ~UART_IIR_NO_INT;
-			}
-		}
-	} else
-		ret =  mem_serial_in(p, offset);
+	if (offset != UART_IIR)
+		return mem_serial_in(p, offset);
+
+	offset <<= p->regshift;
+
+	ret = readl(p->membase + offset);
+	if (!(ret & UART_IIR_NO_INT))
+		return ret;
+
+	/* see if the TX interrupt should have really set */
+	ier = mem_serial_in(p, UART_IER);
+	/* see if the UART's XMIT interrupt is enabled */
+	if (!(ier & UART_IER_THRI))
+		return ret;
+
+	lsr = mem_serial_in(p, UART_LSR);
+	/* now check to see if the UART should be generating an interrupt (but isn't) */
+	if (lsr & (UART_LSR_THRE | UART_LSR_TEMT))
+		ret &= ~UART_IIR_NO_INT;
+
 	return ret;
 }
 
 static void ce4100_mem_serial_out(struct uart_port *p, unsigned int offset, u32 value)
 {
-	offset = offset << p->regshift;
+	offset <<= p->regshift;
 	writel(value, p->membase + offset);
 }