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serial: 8250_dw: set uart clk according to baudrate

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Change-Id: I27f92816b202bbe4fa9d97f7656721661afbaa6e
Signed-off-by: Huibin Hong <huibin.hong@rock-chips.com>
This commit is contained in:
Huibin Hong
2017-09-29 16:44:02 +08:00
committed by Tao Huang
parent 62d96185bd
commit b205560ab1
1 changed files with 38 additions and 0 deletions
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38
drivers/tty/serial/8250/8250_dw.c
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@@ -334,12 +334,49 @@ dw8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old)
static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
struct ktermios *old)
{
#ifndef CONFIG_ARCH_ROCKCHIP
unsigned long newrate = tty_termios_baud_rate(termios) * 16;
#endif
struct dw8250_data *d = to_dw8250_data(p->private_data);
long rate;
#ifdef CONFIG_ARCH_ROCKCHIP
unsigned int baud = tty_termios_baud_rate(termios);
unsigned int rate_temp, diff;
#endif
int ret;
clk_disable_unprepare(d->clk);
#ifdef CONFIG_ARCH_ROCKCHIP
if (baud <= 115200)
rate = 24000000;
else if (baud == 230400)
rate = baud * 16 * 2;
else if (baud == 1152000)
rate = baud * 16 * 2;
else
rate = baud * 16;
ret = clk_set_rate(d->clk, rate);
rate_temp = clk_get_rate(d->clk);
diff = rate * 20 / 1000;
/*
* If rate_temp is not equal to rate, is means fractional frequency
* division is failed. Then use Integer frequency division, and
* the baud rate error must be under -+2%
*/
if ((rate_temp < rate) && ((rate - rate_temp) > diff)) {
ret = clk_set_rate(d->clk, rate + diff);
rate_temp = clk_get_rate(d->clk);
if ((rate_temp < rate) && ((rate - rate_temp) > diff))
dev_info(p->dev, "set rate:%ld, but get rate:%d\n",
rate, rate_temp);
else if ((rate < rate_temp) && ((rate_temp - rate) > diff))
dev_info(p->dev, "set rate:%ld, but get rate:%d\n",
rate, rate_temp);
}
if (!ret)
p->uartclk = rate;
#else
rate = clk_round_rate(d->clk, newrate);
if (rate > 0) {
/*
@@ -353,6 +390,7 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
if (ret)
swap(p->uartclk, rate);
}
#endif
clk_prepare_enable(d->clk);
p->status &= ~UPSTAT_AUTOCTS;