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| author | Alexander Shiyan <shc_work@mail.ru> | 2014-02-07 18:16:04 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-13 09:33:04 -0800 |
| commit | e97e15561cd885926f78200a1e75e713172da60e (patch) | |
| tree | 03146120f801947ec35364278b657fb52026c280 /drivers/tty/serial/max310x.c | |
| parent | d0fd413cffb7cd8efac6d4d192ba62fc2fa60d2d (diff) | |
| download | linux-e97e15561cd885926f78200a1e75e713172da60e.tar.gz linux-e97e15561cd885926f78200a1e75e713172da60e.tar.bz2 linux-e97e15561cd885926f78200a1e75e713172da60e.zip | |
serial: max310x: Setup baud rate generator more precisely
This patch provide more precisely setup of baud rate generator.
If the result of division has a remainder, we use the multiplier
for the base frequency. Additionally, we report result baud rate
back to serial core.
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/max310x.c')
| -rw-r--r-- | drivers/tty/serial/max310x.c | 32 |
1 files changed, 20 insertions, 12 deletions
diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c index 8d71e4047bb3..313bdf0bb21b 100644 --- a/drivers/tty/serial/max310x.c +++ b/drivers/tty/serial/max310x.c @@ -1,7 +1,7 @@ /* * Maxim (Dallas) MAX3107/8/9, MAX14830 serial driver * - * Copyright (C) 2012-2013 Alexander Shiyan <shc_work@mail.ru> + * Copyright (C) 2012-2014 Alexander Shiyan <shc_work@mail.ru> * * Based on max3100.c, by Christian Pellegrin <chripell@evolware.org> * Based on max3110.c, by Feng Tang <feng.tang@intel.com> @@ -504,25 +504,33 @@ static bool max310x_reg_precious(struct device *dev, unsigned int reg) return false; } -static void max310x_set_baud(struct uart_port *port, int baud) +static int max310x_set_baud(struct uart_port *port, int baud) { - unsigned int mode = 0, div = port->uartclk / baud; + unsigned int mode = 0, clk = port->uartclk, div = clk / baud; - if (!(div / 16)) { + /* Check for minimal value for divider */ + if (div < 16) + div = 16; + + if (clk % baud && (div / 16) < 0x8000) { /* Mode x2 */ mode = MAX310X_BRGCFG_2XMODE_BIT; - div = (port->uartclk * 2) / baud; - } - - if (!(div / 16)) { - /* Mode x4 */ - mode = MAX310X_BRGCFG_4XMODE_BIT; - div = (port->uartclk * 4) / baud; + clk = port->uartclk * 2; + div = clk / baud; + + if (clk % baud && (div / 16) < 0x8000) { + /* Mode x4 */ + mode = MAX310X_BRGCFG_4XMODE_BIT; + clk = port->uartclk * 4; + div = clk / baud; + } } max310x_port_write(port, MAX310X_BRGDIVMSB_REG, (div / 16) >> 8); max310x_port_write(port, MAX310X_BRGDIVLSB_REG, div / 16); max310x_port_write(port, MAX310X_BRGCFG_REG, (div % 16) | mode); + + return DIV_ROUND_CLOSEST(clk, div); } static int max310x_update_best_err(unsigned long f, long *besterr) @@ -875,7 +883,7 @@ static void max310x_set_termios(struct uart_port *port, port->uartclk / 4); /* Setup baudrate generator */ - max310x_set_baud(port, baud); + baud = max310x_set_baud(port, baud); /* Update timeout according to new baud rate */ uart_update_timeout(port, termios->c_cflag, baud); |