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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>
This commit is contained in:
Oskar Schirmer 2009-06-11 14:52:23 +01:00 committed by Linus Torvalds
parent 8759ef32d9
commit 534fca068e
2 changed files with 11 additions and 20 deletions
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1
drivers/serial/Kconfig
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@ -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.

30
drivers/serial/imx.c
View File

@ -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