serial: 8250_pci: more BayTrail error-free bauds

Support the following additional baud rates with 0% error:
	500000, 1500000, 2500000, 3500000

Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 29 insertions, 8 deletions

diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 0ff3e3624d4c..a3dbc4d97fa2 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1366,22 +1366,43 @@ byt_set_termios(struct uart_port *p, struct ktermios *termios,
                 struct ktermios *old)
 {
         unsigned int baud = tty_termios_baud_rate(termios);
-        unsigned int m = 6912;
-        unsigned int n = 15625;
+        unsigned int m, n;
         u32 reg;
 
-        /* For baud rates 1M, 2M, 3M and 4M the dividers must be adjusted. */
-        if (baud == 1000000 || baud == 2000000 || baud == 4000000) {
+        /*
+         * For baud rates 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M and 4M the
+         * dividers must be adjusted.
+         *
+         * uartclk = (m / n) * 100 MHz, where m <= n
+         */
+        switch (baud) {
+        case 500000:
+        case 1000000:
+        case 2000000:
+        case 4000000:
                 m = 64;
                 n = 100;
-
                 p->uartclk = 64000000;
-        } else if (baud == 3000000) {
+                break;
+        case 3500000:
+                m = 56;
+                n = 100;
+                p->uartclk = 56000000;
+                break;
+        case 1500000:
+        case 3000000:
                 m = 48;
                 n = 100;
-
                 p->uartclk = 48000000;
-        } else {
+                break;
+        case 2500000:
+                m = 40;
+                n = 100;
+                p->uartclk = 40000000;
+                break;
+        default:
+                m = 6912;
+                n = 15625;
                 p->uartclk = 44236800;
         }