serial: mfd: adjust the baud rate setting

Previous baud rate setting code only has been tested with 3.5M/9600/
115200/230400/460800 bps, and recently we got a 3M bps device to test,
which needs to modify current MUL register setting, and with this
patch 2.5M/2M/1.5M/1M/0.5M should also work as they just use a MUL
value scale down from 3M's.

Also got some reference register setting from silicon guys for
different baud rates, which tries to keep the pre-scalar register value
to 16.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 8 insertions, 16 deletions

diff --git a/drivers/serial/mfd.c b/drivers/serial/mfd.c
index 5fc699e929dc..d40010a22ecd 100644
--- a/drivers/serial/mfd.c
+++ b/drivers/serial/mfd.c
@@ -900,8 +900,7 @@ serial_hsu_set_termios(struct uart_port *port, struct ktermios *termios,
         unsigned char cval, fcr = 0;
         unsigned long flags;
         unsigned int baud, quot;
-        u32 mul = 0x3600;
-        u32 ps = 0x10;
+        u32 ps, mul;
 
         switch (termios->c_cflag & CSIZE) {
         case CS5:
@@ -943,31 +942,24 @@ serial_hsu_set_termios(struct uart_port *port, struct ktermios *termios,
         baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
 
         quot = 1;
+        ps = 0x10;
+        mul = 0x3600;
         switch (baud) {
         case 3500000:
                 mul = 0x3345;
                 ps = 0xC;
                 break;
-        case 3000000:
-                mul = 0x2EE0;
-                break;
-        case 2500000:
-                mul = 0x2710;
-                break;
-        case 2000000:
-                mul = 0x1F40;
-                break;
         case 1843200:
                 mul = 0x2400;
                 break;
+        case 3000000:
+        case 2500000:
+        case 2000000:
         case 1500000:
-                mul = 0x1770;
-                break;
         case 1000000:
-                mul = 0xFA0;
-                break;
         case 500000:
-                mul = 0x7D0;
+                /* mul/ps/quot = 0x9C4/0x10/0x1 will make a 500000 bps */
+                mul = baud / 500000 * 0x9C4;
                 break;
         default:
                 /* Use uart_get_divisor to get quot for other baud rates */