Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161202AbbKSSzt (ORCPT ); Thu, 19 Nov 2015 13:55:49 -0500 Received: from baptiste.telenet-ops.be ([195.130.132.51]:36113 "EHLO baptiste.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758767AbbKSSzn (ORCPT ); Thu, 19 Nov 2015 13:55:43 -0500 From: Geert Uytterhoeven To: Greg Kroah-Hartman , Simon Horman , Magnus Damm , Yoshinori Sato , Laurent Pinchart Cc: linux-serial@vger.kernel.org, linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH 12/25] serial: sh-sci: Merge sci_scbrr_calc() and sci_baud_calc_hscif() Date: Thu, 19 Nov 2015 19:38:51 +0100 Message-Id: <1447958344-836-13-git-send-email-geert+renesas@glider.be> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1447958344-836-1-git-send-email-geert+renesas@glider.be> References: <1447958344-836-1-git-send-email-geert+renesas@glider.be> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3435 Lines: 98 For low bit rates, the for-loop that reduces the divider returned by sci_scbrr_calc() and picks the clock select value may terminate without finding suitable values, leading to out-of-range divider and clock select values. sci_baud_calc_hscif() doesn't suffer from this problem, as it correctly uses clamp(). Since there are only two relevant differences between HSCIF and other variants w.r.t. bit rate configuration (fixed vs. variable sample rate, and an additional factor of two), sci_scbrr_calc() and sci_baud_calc_hscif() can be merged, fixing the issue with out-of-range values. Signed-off-by: Geert Uytterhoeven --- drivers/tty/serial/sh-sci.c | 42 +++++++++++++++++++----------------------- 1 file changed, 19 insertions(+), 23 deletions(-) diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index c2ab29ddedbc26a2..dccea5df5355076a 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1860,20 +1860,24 @@ static void sci_shutdown(struct uart_port *port) sci_free_irq(s); } -static unsigned int sci_scbrr_calc(struct sci_port *s, unsigned int bps, - unsigned long freq) +/* calculate sample rate, BRR, and clock select */ +static void sci_scbrr_calc(struct sci_port *s, unsigned int bps, + unsigned long freq, int *brr, unsigned int *srr, + unsigned int *cks) { - return DIV_ROUND_CLOSEST(freq, s->sampling_rate * bps) - 1; -} - -/* calculate sample rate, BRR, and clock select for HSCIF */ -static void sci_baud_calc_hscif(struct sci_port *s, unsigned int bps, - unsigned long freq, int *brr, - unsigned int *srr, unsigned int *cks) -{ - unsigned int sr, br, a, b, c; + unsigned int min_sr, max_sr, shift, sr, br, a, b, c; int err, min_err = INT_MAX; + if (s->sampling_rate) { + min_sr = max_sr = s->sampling_rate; + shift = 0; + } else { + /* HSCIF has a variable sample rate */ + min_sr = 8; + max_sr = 32; + shift = 1; + } + /* * Find the combination of sample rate and clock select with the * smallest deviation from the desired baud rate. @@ -1889,10 +1893,10 @@ static void sci_baud_calc_hscif(struct sci_port *s, unsigned int bps, * (|D - 0.5| / N * (1 + F))| * NOTE: Usually, treat D for 0.5, F is 0 by this calculation. */ - for (sr = 32; sr >= 8; sr--) { + for (sr = max_sr; sr >= min_sr; sr--) { for (c = 0; c <= 3; c++) { /* integerized formulas from HSCIF documentation */ - a = sr * (1 << (2 * c + 1)); + a = sr * (1 << (2 * c + shift)); if (bps > UINT_MAX / a) break; @@ -1960,16 +1964,8 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios, max_baud = port->uartclk ? port->uartclk / 16 : 115200; baud = uart_get_baud_rate(port, termios, old, 0, max_baud); - if (likely(baud && port->uartclk)) { - if (s->cfg->type == PORT_HSCIF) { - sci_baud_calc_hscif(s, baud, port->uartclk, &t, &srr, - &cks); - } else { - t = sci_scbrr_calc(s, baud, port->uartclk); - for (cks = 0; t >= 256 && cks <= 3; cks++) - t >>= 2; - } - } + if (likely(baud && port->uartclk)) + sci_scbrr_calc(s, baud, port->uartclk, &t, &srr, &cks); sci_port_enable(s); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/