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serial: 8250-mtk: add follow control 

Add SW and HW follow control function.

Signed-off-by: Long Cheng <long.cheng@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.2
Long Cheng 2019-04-25 16:41:30 +08:00 committed by Greg Kroah-Hartman
parent f137401780
commit 8ceeb47098
1 changed files with 37 additions and 23 deletions
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60
drivers/tty/serial/8250/8250_mtk.c
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@ -21,12 +21,14 @@
#include "8250.h"
#define UART_MTK_HIGHS 0x09 /* Highspeed register */
#define UART_MTK_SAMPLE_COUNT 0x0a /* Sample count register */
#define UART_MTK_SAMPLE_POINT 0x0b /* Sample point register */
#define MTK_UART_HIGHS 0x09 /* Highspeed register */
#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_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_DMA_EN_TX 0x2
#define MTK_UART_DMA_EN_RX 0x5
@ -46,6 +48,7 @@ enum dma_rx_status {
struct mtk8250_data {
int line;
unsigned int rx_pos;
unsigned int clk_count;
struct clk *uart_clk;
struct clk *bus_clk;
struct uart_8250_dma *dma;
@ -196,9 +199,15 @@ static void
mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
unsigned short fraction_L_mapping[] = {
0, 1, 0x5, 0x15, 0x55, 0x57, 0x57, 0x77, 0x7F, 0xFF, 0xFF
};
unsigned short fraction_M_mapping[] = {
0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 3
};
struct uart_8250_port *up = up_to_u8250p(port);
unsigned int baud, quot, fraction;
unsigned long flags;
unsigned int baud, quot;
#ifdef CONFIG_SERIAL_8250_DMA
if (up->dma) {
@ -214,7 +223,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
serial8250_do_set_termios(port, termios, old);
/*
* Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS)
* Mediatek UARTs use an extra highspeed register (MTK_UART_HIGHS)
*
* We need to recalcualte the quot register, as the claculation depends
* on the vaule in the highspeed register.
@ -230,18 +239,11 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
port->uartclk / 16 / UART_DIV_MAX,
port->uartclk);
if (baud <= 115200) {
serial_port_out(port, UART_MTK_HIGHS, 0x0);
if (baud < 115200) {
serial_port_out(port, MTK_UART_HIGHS, 0x0);
quot = uart_get_divisor(port, baud);
} else if (baud <= 576000) {
serial_port_out(port, UART_MTK_HIGHS, 0x2);
/* Set to next lower baudrate supported */
if ((baud == 500000) || (baud == 576000))
baud = 460800;
quot = DIV_ROUND_UP(port->uartclk, 4 * baud);
} else {
serial_port_out(port, UART_MTK_HIGHS, 0x3);
serial_port_out(port, MTK_UART_HIGHS, 0x3);
quot = DIV_ROUND_UP(port->uartclk, 256 * baud);
}
@ -258,17 +260,29 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
/* reset DLAB */
serial_port_out(port, UART_LCR, up->lcr);
if (baud > 460800) {
if (baud >= 115200) {
unsigned int tmp;
tmp = DIV_ROUND_CLOSEST(port->uartclk, quot * baud);
serial_port_out(port, UART_MTK_SAMPLE_COUNT, tmp - 1);
serial_port_out(port, UART_MTK_SAMPLE_POINT,
(tmp - 2) >> 1);
tmp = (port->uartclk / (baud * quot)) - 1;
serial_port_out(port, MTK_UART_SAMPLE_COUNT, tmp);
serial_port_out(port, MTK_UART_SAMPLE_POINT,
(tmp >> 1) - 1);
/*count fraction to set fractoin register */
fraction = ((port->uartclk * 100) / baud / quot) % 100;
fraction = DIV_ROUND_CLOSEST(fraction, 10);
serial_port_out(port, MTK_UART_FRACDIV_L,
fraction_L_mapping[fraction]);
serial_port_out(port, MTK_UART_FRACDIV_M,
fraction_M_mapping[fraction]);
} else {
serial_port_out(port, UART_MTK_SAMPLE_COUNT, 0x00);
serial_port_out(port, UART_MTK_SAMPLE_POINT, 0xff);
serial_port_out(port, MTK_UART_SAMPLE_COUNT, 0x00);
serial_port_out(port, MTK_UART_SAMPLE_POINT, 0xff);
serial_port_out(port, MTK_UART_FRACDIV_L, 0x00);
serial_port_out(port, MTK_UART_FRACDIV_M, 0x00);
}
if (uart_console(port))
up->port.cons->cflag = termios->c_cflag;
spin_unlock_irqrestore(&port->lock, flags);
/* Don't rewrite B0 */