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>

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index c1fdbc0..959fd85 100644 (file)
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -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 */