diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/serial/omap-serial.c | 38 |
1 files changed, 28 insertions, 10 deletions
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 6f3dbf740f05..9915e4d1418c 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -232,24 +232,42 @@ static void serial_omap_enable_wakeup(struct uart_omap_port *up, bool enable) } /* + * serial_omap_baud_is_mode16 - check if baud rate is MODE16X + * @port: uart port info + * @baud: baudrate for which mode needs to be determined + * + * Returns true if baud rate is MODE16X and false if MODE13X + * Original table in OMAP TRM named "UART Mode Baud Rates, Divisor Values, + * and Error Rates" determines modes not for all common baud rates. + * E.g. for 1000000 baud rate mode must be 16x, but according to that + * table it's determined as 13x. + */ +static bool +serial_omap_baud_is_mode16(struct uart_port *port, unsigned int baud) +{ + unsigned int n13 = port->uartclk / (13 * baud); + unsigned int n16 = port->uartclk / (16 * baud); + int baudAbsDiff13 = baud - (port->uartclk / (13 * n13)); + int baudAbsDiff16 = baud - (port->uartclk / (16 * n16)); + if(baudAbsDiff13 < 0) + baudAbsDiff13 = -baudAbsDiff13; + if(baudAbsDiff16 < 0) + baudAbsDiff16 = -baudAbsDiff16; + + return (baudAbsDiff13 > baudAbsDiff16); +} + +/* * serial_omap_get_divisor - calculate divisor value * @port: uart port info * @baud: baudrate for which divisor needs to be calculated. - * - * We have written our own function to get the divisor so as to support - * 13x mode. 3Mbps Baudrate as an different divisor. - * Reference OMAP TRM Chapter 17: - * Table 17-1. UART Mode Baud Rates, Divisor Values, and Error Rates - * referring to oversampling - divisor value - * baudrate 460,800 to 3,686,400 all have divisor 13 - * except 3,000,000 which has divisor value 16 */ static unsigned int serial_omap_get_divisor(struct uart_port *port, unsigned int baud) { unsigned int divisor; - if (baud > OMAP_MODE13X_SPEED && baud != 3000000) + if (!serial_omap_baud_is_mode16(port, baud)) divisor = 13; else divisor = 16; @@ -916,7 +934,7 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios, serial_out(up, UART_EFR, up->efr); serial_out(up, UART_LCR, cval); - if (baud > 230400 && baud != 3000000) + if (!serial_omap_baud_is_mode16(port, baud)) up->mdr1 = UART_OMAP_MDR1_13X_MODE; else up->mdr1 = UART_OMAP_MDR1_16X_MODE; |