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When we detect that a 16550 was in fact part of a NatSemi SuperIO chip

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with high-speed mode enabled, we switch it to high-speed mode so that
baud_base becomes 921600. However, we also need to multiply the baud
divisor by 8 at the same time, in case it's already in use as a console.

Signed-off-by: David Woodhouse
Acked-by: Tom Rini
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
David Woodhouse 2005-05-21 15:52:23 +01:00 committed by Russell King
parent 9636273dae
commit 857dde2e79
1 changed files with 13 additions and 6 deletions
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19
drivers/serial/8250.c
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@ -682,8 +682,6 @@ static void autoconfig_16550a(struct uart_8250_port *up)
* from EXCR1. Switch back to bank 0, change it in MCR. Then
* switch back to bank 2, read it from EXCR1 again and check
* it's changed. If so, set baud_base in EXCR2 to 921600. -- dwmw2
* On PowerPC we don't want to change baud_base, as we have
* a number of different divisors. -- Tom Rini
*/
serial_outp(up, UART_LCR, 0);
status1 = serial_in(up, UART_MCR);
@ -699,16 +697,25 @@ static void autoconfig_16550a(struct uart_8250_port *up)
serial_outp(up, UART_MCR, status1);
if ((status2 ^ status1) & UART_MCR_LOOP) {
#ifndef CONFIG_PPC
unsigned short quot;
serial_outp(up, UART_LCR, 0xE0);
quot = serial_inp(up, UART_DLM) << 8;
quot += serial_inp(up, UART_DLL);
quot <<= 3;
status1 = serial_in(up, 0x04); /* EXCR1 */
status1 &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */
status1 |= 0x10; /* 1.625 divisor for baud_base --> 921600 */
serial_outp(up, 0x04, status1);
serial_outp(up, UART_LCR, 0);
up->port.uartclk = 921600*16;
#endif
serial_outp(up, UART_DLL, quot & 0xff);
serial_outp(up, UART_DLM, quot >> 8);
serial_outp(up, UART_LCR, 0);
up->port.uartclk = 921600*16;
up->port.type = PORT_NS16550A;
up->capabilities |= UART_NATSEMI;
return;