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[ltsi-3.10,019/286] serial: sh-sci: Simplify baud rate calculation algorithms

Message ID 1388135720-12832-20-git-send-email-horms+renesas@verge.net.au (mailing list archive)
State New, archived
Headers show

Commit Message

Simon Horman Dec. 27, 2013, 9:10 a.m. UTC 
From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

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>
(cherry picked from commit 6557b1f69ea0961efde7ab33bfe0cb7e3bfed54e)
(Queued by Simon Horman for v3.14 but not yet in Linus's tree)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
---
 drivers/tty/serial/sh-sci.c | 8 ++++----
 include/linux/serial_sci.h  | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)
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Patch

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 80a9103..94e878ca 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 803068d..eb787d4 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 */
 };