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serial: 8250-mtk: modify baudrate setting
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In termios function, add Fractional divider to adjust baudrate.

Signed-off-by: Long Cheng <long.cheng@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Long Cheng authored and Greg Kroah-Hartman committed Apr 25, 2019
1 parent 8ceeb47 commit bdbd0a7
Showing 1 changed file with 102 additions and 0 deletions.
102 changes: 102 additions & 0 deletions drivers/tty/serial/8250/8250_mtk.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,13 +25,28 @@
#define MTK_UART_SAMPLE_COUNT 0x0a /* Sample count register */
#define MTK_UART_SAMPLE_POINT 0x0b /* Sample point register */
#define MTK_UART_RATE_FIX 0x0d /* UART Rate Fix Register */
#define MTK_UART_ESCAPE_DAT 0x10 /* Escape Character register */
#define MTK_UART_ESCAPE_EN 0x11 /* Escape Enable register */
#define MTK_UART_DMA_EN 0x13 /* DMA Enable register */
#define MTK_UART_RXTRI_AD 0x14 /* RX Trigger address */
#define MTK_UART_FRACDIV_L 0x15 /* Fractional divider LSB address */
#define MTK_UART_FRACDIV_M 0x16 /* Fractional divider MSB address */
#define MTK_UART_IER_XOFFI 0x20 /* Enable XOFF character interrupt */
#define MTK_UART_IER_RTSI 0x40 /* Enable RTS Modem status interrupt */
#define MTK_UART_IER_CTSI 0x80 /* Enable CTS Modem status interrupt */

#define MTK_UART_EFR_EN 0x10 /* Enable enhancement feature */
#define MTK_UART_EFR_RTS 0x40 /* Enable hardware rx flow control */
#define MTK_UART_EFR_CTS 0x80 /* Enable hardware tx flow control */
#define MTK_UART_EFR_NO_SW_FC 0x0 /* no sw flow control */
#define MTK_UART_EFR_XON1_XOFF1 0xa /* XON1/XOFF1 as sw flow control */
#define MTK_UART_EFR_XON2_XOFF2 0x5 /* XON2/XOFF2 as sw flow control */
#define MTK_UART_EFR_SW_FC_MASK 0xf /* Enable CTS Modem status interrupt */
#define MTK_UART_EFR_HW_FC (MTK_UART_EFR_RTS | MTK_UART_EFR_CTS)
#define MTK_UART_DMA_EN_TX 0x2
#define MTK_UART_DMA_EN_RX 0x5

#define MTK_UART_ESCAPE_CHAR 0x77 /* Escape char added under sw fc */
#define MTK_UART_TX_SIZE UART_XMIT_SIZE
#define MTK_UART_RX_SIZE 0x8000
#define MTK_UART_TX_TRIGGER 1
Expand All @@ -57,6 +72,13 @@ struct mtk8250_data {
#endif
};

/* flow control mode */
enum {
MTK_UART_FC_NONE,
MTK_UART_FC_SW,
MTK_UART_FC_HW,
};

#ifdef CONFIG_SERIAL_8250_DMA
static void mtk8250_rx_dma(struct uart_8250_port *up);

Expand Down Expand Up @@ -195,6 +217,75 @@ static void mtk8250_shutdown(struct uart_port *port)
return serial8250_do_shutdown(port);
}

static void mtk8250_disable_intrs(struct uart_8250_port *up, int mask)
{
serial_out(up, UART_IER, serial_in(up, UART_IER) & (~mask));
}

static void mtk8250_enable_intrs(struct uart_8250_port *up, int mask)
{
serial_out(up, UART_IER, serial_in(up, UART_IER) | mask);
}

static void mtk8250_set_flow_ctrl(struct uart_8250_port *up, int mode)
{
struct uart_port *port = &up->port;
int lcr = serial_in(up, UART_LCR);

serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
serial_out(up, UART_EFR, UART_EFR_ECB);
serial_out(up, UART_LCR, lcr);
lcr = serial_in(up, UART_LCR);

switch (mode) {
case MTK_UART_FC_NONE:
serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
serial_out(up, MTK_UART_ESCAPE_EN, 0x00);
serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
serial_out(up, UART_EFR, serial_in(up, UART_EFR) &
(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK)));
serial_out(up, UART_LCR, lcr);
mtk8250_disable_intrs(up, MTK_UART_IER_XOFFI |
MTK_UART_IER_RTSI | MTK_UART_IER_CTSI);
break;

case MTK_UART_FC_HW:
serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
serial_out(up, MTK_UART_ESCAPE_EN, 0x00);
serial_out(up, UART_MCR, UART_MCR_RTS);
serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);

/*enable hw flow control*/
serial_out(up, UART_EFR, MTK_UART_EFR_HW_FC |
(serial_in(up, UART_EFR) &
(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK))));

serial_out(up, UART_LCR, lcr);
mtk8250_disable_intrs(up, MTK_UART_IER_XOFFI);
mtk8250_enable_intrs(up, MTK_UART_IER_CTSI | MTK_UART_IER_RTSI);
break;

case MTK_UART_FC_SW: /*MTK software flow control */
serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
serial_out(up, MTK_UART_ESCAPE_EN, 0x01);
serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);

/*enable sw flow control */
serial_out(up, UART_EFR, MTK_UART_EFR_XON1_XOFF1 |
(serial_in(up, UART_EFR) &
(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK))));

serial_out(up, UART_XON1, START_CHAR(port->state->port.tty));
serial_out(up, UART_XOFF1, STOP_CHAR(port->state->port.tty));
serial_out(up, UART_LCR, lcr);
mtk8250_disable_intrs(up, MTK_UART_IER_CTSI|MTK_UART_IER_RTSI);
mtk8250_enable_intrs(up, MTK_UART_IER_XOFFI);
break;
default:
break;
}
}

static void
mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
Expand All @@ -208,6 +299,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
struct uart_8250_port *up = up_to_u8250p(port);
unsigned int baud, quot, fraction;
unsigned long flags;
int mode;

#ifdef CONFIG_SERIAL_8250_DMA
if (up->dma) {
Expand Down Expand Up @@ -281,6 +373,16 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
serial_port_out(port, MTK_UART_FRACDIV_L, 0x00);
serial_port_out(port, MTK_UART_FRACDIV_M, 0x00);
}

if ((termios->c_cflag & CRTSCTS) && (!(termios->c_iflag & CRTSCTS)))
mode = MTK_UART_FC_HW;
else if (termios->c_iflag & CRTSCTS)
mode = MTK_UART_FC_SW;
else
mode = MTK_UART_FC_NONE;

mtk8250_set_flow_ctrl(up, mode);

if (uart_console(port))
up->port.cons->cflag = termios->c_cflag;

Expand Down

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