serial: mfd: add more baud rates support

Add more baud rates support referring the baud_table[] defined
in drivers/char/tty_ioctl.c: 3000000/2000000/1000000/500000

Signed-off-by: Feng Tang <feng.tang@intel.com>
Acked-by: Alan Cox <alan.cox@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 27 insertions, 14 deletions

diff --git a/drivers/serial/mfd.c b/drivers/serial/mfd.c
index ad35130cd8a0..735799e30aa9 100644
--- a/drivers/serial/mfd.c
+++ b/drivers/serial/mfd.c
@@ -929,39 +929,52 @@ serial_hsu_set_termios(struct uart_port *port, struct ktermios *termios,
                 cval |= UART_LCR_EPAR;
 
         /*
+         * The base clk is 50Mhz, and the baud rate come from:
+         *      baud = 50M * MUL / (DIV * PS * DLAB)
+         *
          * For those basic low baud rate we can get the direct
-         * scalar from 2746800, like 115200 = 2746800/24, for those
-         * higher baud rate, we have to handle them case by case,
-         * but DIV reg is never touched as its default value 0x3d09
+         * scalar from 2746800, like 115200 = 2746800/24. For those
+         * higher baud rate, we handle them case by case, mainly by
+         * adjusting the MUL/PS registers, and DIV register is kept
+         * as default value 0x3d09 to make things simple
          */
         baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
-        quot = uart_get_divisor(port, baud);
 
+        quot = 1;
         switch (baud) {
         case 3500000:
                 mul = 0x3345;
                 ps = 0xC;
-                quot = 1;
+                break;
+        case 3000000:
+                mul = 0x2EE0;
                 break;
         case 2500000:
                 mul = 0x2710;
-                ps = 0x10;
-                quot = 1;
                 break;
-        case 18432000:
+        case 2000000:
+                mul = 0x1F40;
+                break;
+        case 1843200:
                 mul = 0x2400;
-                ps = 0x10;
-                quot = 1;
                 break;
         case 1500000:
-                mul = 0x1D4C;
-                ps = 0xc;
-                quot = 1;
+                mul = 0x1770;
+                break;
+        case 1000000:
+                mul = 0xFA0;
+                break;
+        case 500000:
+                mul = 0x7D0;
                 break;
         default:
-                ;
+                /* Use uart_get_divisor to get quot for other baud rates */
+                quot = 0;
         }
 
+        if (!quot)
+                quot = uart_get_divisor(port, baud);
+
         if ((up->port.uartclk / quot) < (2400 * 16))
                 fcr = UART_FCR_ENABLE_FIFO | UART_FCR_HSU_64_1B;
         else if ((up->port.uartclk / quot) < (230400 * 16))