This patch replaces a case switch by a serial8250_get_ps() call that does
necessary calculations for byt_set_termios().
Below is a list of the calculations done for all defined baud rates. Each line
in a format: 1) nominator, 2) denominator, 3) prescaler, 4) Fuart, 5) port UART
clock, 6) list of baud rates with DLAB values.
4 5 16 80000000 80000000 2500000(2)
14 25 16 56000000 56000000 3500000(1)
16 25 16 64000000 64000000 500000(8),1000000(4),2000000(2),4000000(1)
24 25 16 96000000 96000000 1500000(4),3000000(2)
2304 3125 16 73728000 73728000 576000(8),1152000(4)
8192 15625 16 52428800 52428800 50(65536),200(16384)
9216 15625 16 58982400 58982400 1800(2048),57600(64),115200(32),230400(16),460800(8),921600(4),1843200(2)
12288 15625 16 78643200 78643200 75(65536),150(32768),300(16384),600(8192),1200(4096),2400(2048),4800(1024),9600(512),19200(256),38400(128)
11264 19531 16 57672418 57671680 110(32768)
17152 24414 16 70254771 70254592 134(32768)
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_pci.c | 36 ++++++------------------------------
1 file changed, 6 insertions(+), 30 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 11784e9..544d11b 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1401,37 +1401,13 @@ byt_set_termios(struct uart_port *p, struct ktermios *termios,
* dividers must be adjusted.
*
* uartclk = (m / n) * 100 MHz, where m <= n
+ *
+ * For now we ignore a prescaler value since it will be always 16 for
+ * standard baud rates.
+ *
+ * Note, that the formula will not work for rates less than 110 baud.
*/
- switch (baud) {
- case 500000:
- case 1000000:
- case 2000000:
- case 4000000:
- m = 64;
- n = 100;
- p->uartclk = 64000000;
- break;
- case 3500000:
- m = 56;
- n = 100;
- p->uartclk = 56000000;
- break;
- case 1500000:
- case 3000000:
- m = 48;
- n = 100;
- p->uartclk = 48000000;
- break;
- case 2500000:
- m = 40;
- n = 100;
- p->uartclk = 40000000;
- break;
- default:
- m = 2304;
- n = 3125;
- p->uartclk = 73728000;
- }
+ serial8250_get_ps(p, baud, 100000000, 15, &m, &n);
/* Reset the clock */
reg = (m << BYT_PRV_CLK_M_VAL_SHIFT) | (n << BYT_PRV_CLK_N_VAL_SHIFT);
--
2.1.4
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