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serial: 8250: Refactor divisor programming 

Refactor divisor register programming into a new function,
serial8250_set_divisor; this allows serial console to reinitialize
early after resume from suspend.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2015-01-22 12:24:28 -05:00 committed by Greg Kroah-Hartman
parent 0ec3f585cf
commit e72abd5da0
1 changed files with 48 additions and 39 deletions
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87
drivers/tty/serial/8250/8250_core.c
View File

@ -2478,6 +2478,50 @@ static unsigned char serial8250_compute_lcr(struct uart_8250_port *up,
return cval;
}
void serial8250_set_divisor(struct uart_port *port, unsigned int baud,
unsigned int quot)
{
struct uart_8250_port *up = up_to_u8250p(port);
/* Workaround to enable 115200 baud on OMAP1510 internal ports */
if (is_omap1510_8250(up)) {
if (baud == 115200) {
quot = 1;
serial_port_out(port, UART_OMAP_OSC_12M_SEL, 1);
} else
serial_port_out(port, UART_OMAP_OSC_12M_SEL, 0);
}
/*
* For NatSemi, switch to bank 2 not bank 1, to avoid resetting EXCR2,
* otherwise just set DLAB
*/
if (up->capabilities & UART_NATSEMI)
serial_port_out(port, UART_LCR, 0xe0);
else
serial_port_out(port, UART_LCR, up->lcr | UART_LCR_DLAB);
serial_dl_write(up, quot);
/*
* XR17V35x UARTs have an extra fractional divisor register (DLD)
*
* We need to recalculate all of the registers, because DLM and DLL
* are already rounded to a whole integer.
*
* When recalculating we use a 32x clock instead of a 16x clock to
* allow 1-bit for rounding in the fractional part.
*/
if (up->port.type == PORT_XR17V35X) {
unsigned int baud_x32 = (port->uartclk * 2) / baud;
u16 quot = baud_x32 / 32;
u8 quot_frac = DIV_ROUND_CLOSEST(baud_x32 % 32, 2);
serial_dl_write(up, quot);
serial_port_out(port, 0x2, quot_frac & 0xf);
}
}
void
serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
@ -2526,6 +2570,8 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
serial8250_rpm_get(up);
spin_lock_irqsave(&port->lock, flags);
up->lcr = cval; /* Save computed LCR */
/*
* Update the per-port timeout.
*/
@ -2590,43 +2636,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
serial_port_out(port, UART_EFR, efr);
}
/* Workaround to enable 115200 baud on OMAP1510 internal ports */
if (is_omap1510_8250(up)) {
if (baud == 115200) {
quot = 1;
serial_port_out(port, UART_OMAP_OSC_12M_SEL, 1);
} else
serial_port_out(port, UART_OMAP_OSC_12M_SEL, 0);
}
/*
* For NatSemi, switch to bank 2 not bank 1, to avoid resetting EXCR2,
* otherwise just set DLAB
*/
if (up->capabilities & UART_NATSEMI)
serial_port_out(port, UART_LCR, 0xe0);
else
serial_port_out(port, UART_LCR, cval | UART_LCR_DLAB);
serial_dl_write(up, quot);
/*
* XR17V35x UARTs have an extra fractional divisor register (DLD)
*
* We need to recalculate all of the registers, because DLM and DLL
* are already rounded to a whole integer.
*
* When recalculating we use a 32x clock instead of a 16x clock to
* allow 1-bit for rounding in the fractional part.
*/
if (up->port.type == PORT_XR17V35X) {
unsigned int baud_x32 = (port->uartclk * 2) / baud;
u16 quot = baud_x32 / 32;
u8 quot_frac = DIV_ROUND_CLOSEST(baud_x32 % 32, 2);
serial_dl_write(up, quot);
serial_port_out(port, 0x2, quot_frac & 0xf);
}
serial8250_set_divisor(port, baud, quot);
/*
* LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR
@ -2635,8 +2645,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
if (port->type == PORT_16750)
serial_port_out(port, UART_FCR, up->fcr);
serial_port_out(port, UART_LCR, cval); /* reset DLAB */
up->lcr = cval; /* Save LCR */
serial_port_out(port, UART_LCR, up->lcr); /* reset DLAB */
if (port->type != PORT_16750) {
/* emulated UARTs (Lucent Venus 167x) need two steps */
if (up->fcr & UART_FCR_ENABLE_FIFO)