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serial: sh-sci: support lower baud rate 

Support prescaler 1/16 and 1/64, in addition to current 1 and 1/4.

Supporting below 2400bps was dropped long time ago in mainline.
Since then, setting lower rate has been resulting in erroneous
register value, without indicating any errors through API.

This patch adds more prescaler to support lower rates again.
This still doesn't check range, but we won't hit the case because
even 50bps at 48MHz clock is now supported.

Signed-off-by: Takashi Yoshii <takashi.yoshii.zj@renesas.com>
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Yoshii 2012-11-16 10:52:49 +09:00 committed by Greg Kroah-Hartman
parent 4ffc3cdb64
commit 9d482cc353
1 changed files with 8 additions and 11 deletions
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19
drivers/tty/serial/sh-sci.c
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@ -1815,7 +1815,7 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
{
struct sci_port *s = to_sci_port(port);
struct plat_sci_reg *reg;
unsigned int baud, smr_val, max_baud;
unsigned int baud, smr_val, max_baud, cks;
int t = -1;
/*
@ -1849,21 +1849,18 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
uart_update_timeout(port, termios->c_cflag, baud);
serial_port_out(port, SCSMR, smr_val);
for (cks = 0; t >= 256 && cks <= 3; cks++)
t >>= 2;
dev_dbg(port->dev, "%s: SMR %x, t %x, SCSCR %x\n", __func__, smr_val, t,
s->cfg->scscr);
dev_dbg(port->dev, "%s: SMR %x, cks %x, t %x, SCSCR %x\n",
__func__, smr_val, cks, t, s->cfg->scscr);
if (t >= 0) {
if (t >= 256) {
serial_port_out(port, SCSMR, (serial_port_in(port, SCSMR) & ~3) | 1);
t >>= 2;
} else
serial_port_out(port, SCSMR, serial_port_in(port, SCSMR) & ~3);
serial_port_out(port, SCSMR, (smr_val & ~3) | cks);
serial_port_out(port, SCBRR, t);
udelay((1000000+(baud-1)) / baud); /* Wait one bit interval */
}
} else
serial_port_out(port, SCSMR, smr_val);
sci_init_pins(port, termios->c_cflag);