imx: serial: use rational library function

for calculation of numerator and denominator
used in baud rate setting, use generic library function
for optimum settings.

Signed-off-by: Oskar Schirmer <os@emlix.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 3391ef0d761da7b031f6581a35f5659beea3e637..641e800ed69333fbafc3b06dd982a0a3ec7f7605 100644 (file)
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -833,6 +833,7 @@ config SERIAL_IMX
        bool "IMX serial port support"
        depends on ARM && (ARCH_IMX || ARCH_MXC)
        select SERIAL_CORE
+       select RATIONAL
        help
          If you have a machine based on a Motorola IMX CPU you
          can enable its onboard serial port by enabling this option.

diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c
index cbd4f322464326bb335ca8548a95a899c73a28a5..0de81f71f8848f95d11f72b0b43f6d23768861e5 100644 (file)
--- a/drivers/serial/imx.c
+++ b/drivers/serial/imx.c
@@ -41,6 +41,7 @@
 #include <linux/serial_core.h>
 #include <linux/serial.h>
 #include <linux/clk.h>
+#include <linux/rational.h>
 
 #include <asm/io.h>
 #include <asm/irq.h>
@@ -670,7 +671,8 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
        unsigned long flags;
        unsigned int ucr2, old_ucr1, old_txrxen, baud, quot;
        unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
-       unsigned int div, num, denom, ufcr;
+       unsigned int div, ufcr;
+       unsigned long num, denom;
 
        /*
         * If we don't support modem control lines, don't allow
@@ -772,32 +774,20 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
        if (!div)
                div = 1;
 
-       num = baud;
-       denom = port->uartclk / div / 16;
+       rational_best_approximation(16 * div * baud, sport->port.uartclk,
+               1 << 16, 1 << 16, &num, &denom);
 
-       /* shift num and denom right until they fit into 16 bits */
-       while (num > 0x10000 || denom > 0x10000) {
-               num >>= 1;
-               denom >>= 1;
-       }
-       if (num > 0)
-               num -= 1;
-       if (denom > 0)
-               denom -= 1;
-
-       writel(num, sport->port.membase + UBIR);
-       writel(denom, sport->port.membase + UBMR);
-
-       if (div == 7)
-               div = 6; /* 6 in RFDIV means divide by 7 */
-       else
-               div = 6 - div;
+       num -= 1;
+       denom -= 1;
 
        ufcr = readl(sport->port.membase + UFCR);
        ufcr = (ufcr & (~UFCR_RFDIV)) |
            (div << 7);
        writel(ufcr, sport->port.membase + UFCR);
 
+       writel(num, sport->port.membase + UBIR);
+       writel(denom, sport->port.membase + UBMR);
+
 #ifdef ONEMS
        writel(sport->port.uartclk / div / 1000, sport->port.membase + ONEMS);
 #endif