From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Date: Fri, 6 Dec 2013 09:59:12 +0000 (+0100)
Subject: serial: sh-sci: Simplify baud rate calculation algorithms
X-Git-Tag: v3.14-rc1~114^2~2^2~8
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6557b1f69ea0961efde7ab33bfe0cb7e3bfed54e;p=kernel%2Fkernel-generic.git

serial: sh-sci: Simplify baud rate calculation algorithms

Rewrite the baud rate register value calculations in easier to read
forms. The computed value isn't modified.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
---

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index eb59bb2..f2fad4d 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1818,13 +1818,13 @@ static unsigned int sci_scbrr_calc(unsigned int algo_id, unsigned int bps,
 {
 	switch (algo_id) {
 	case SCBRR_ALGO_1:
-		return ((freq + 16 * bps) / (16 * bps) - 1);
+		return freq / (16 * bps);
 	case SCBRR_ALGO_2:
-		return ((freq + 16 * bps) / (32 * bps) - 1);
+		return DIV_ROUND_CLOSEST(freq, 32 * bps) - 1;
 	case SCBRR_ALGO_3:
-		return (((freq * 2) + 16 * bps) / (16 * bps) - 1);
+		return freq / (8 * bps);
 	case SCBRR_ALGO_4:
-		return (((freq * 2) + 16 * bps) / (32 * bps) - 1);
+		return DIV_ROUND_CLOSEST(freq, 16 * bps) - 1;
 	}
 
 	/* Warn, but use a safe default */
diff --git a/include/linux/serial_sci.h b/include/linux/serial_sci.h
index babc5fe..12cf50c 100644
--- a/include/linux/serial_sci.h
+++ b/include/linux/serial_sci.h
@@ -11,10 +11,10 @@
 #define SCIx_NOT_SUPPORTED	(-1)
 
 enum {
-	SCBRR_ALGO_1,		/* ((clk + 16 * bps) / (16 * bps) - 1) */
-	SCBRR_ALGO_2,		/* ((clk + 16 * bps) / (32 * bps) - 1) */
-	SCBRR_ALGO_3,		/* (((clk * 2) + 16 * bps) / (16 * bps) - 1) */
-	SCBRR_ALGO_4,		/* (((clk * 2) + 16 * bps) / (32 * bps) - 1) */
+	SCBRR_ALGO_1,		/* clk / (16 * bps) */
+	SCBRR_ALGO_2,		/* DIV_ROUND_CLOSEST(clk, 32 * bps) - 1 */
+	SCBRR_ALGO_3,		/* clk / (8 * bps) */
+	SCBRR_ALGO_4,		/* DIV_ROUND_CLOSEST(clk, 16 * bps) - 1 */
 	SCBRR_ALGO_6,		/* HSCIF variable sample rate algorithm */
 };