Messages in this thread | | | Date | Fri, 12 Jun 2009 09:16:49 +0200 | From | Sascha Hauer <> | Subject | Re: [PATCH 7/9 -v2] imx: serial: use rational library function |
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Hi Oskar,
On Wed, Jun 10, 2009 at 02:08:34PM +0200, Oskar Schirmer wrote: > 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> > --- > drivers/serial/Kconfig | 1 + > drivers/serial/imx.c | 30 ++++++++++-------------------- > 2 files changed, 11 insertions(+), 20 deletions(-) > > diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig > index 343e3a3..0ecb4c4 100644 > --- 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 60892a2..11f93e2 100644 > --- 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);
Reading the example you have given for rational_best_approximation() in the last patch this should be (1 << 16) - 1, right?
> > - /* 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 > -- > 1.5.3.7 > >
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